--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/persistentstorage/sql/SQLite/pager.c Fri Jan 22 11:06:30 2010 +0200
@@ -0,0 +1,5377 @@
+/*
+** 2001 September 15
+**
+** The author disclaims copyright to this source code. In place of
+** a legal notice, here is a blessing:
+**
+** May you do good and not evil.
+** May you find forgiveness for yourself and forgive others.
+** May you share freely, never taking more than you give.
+**
+*************************************************************************
+** This is the implementation of the page cache subsystem or "pager".
+**
+** The pager is used to access a database disk file. It implements
+** atomic commit and rollback through the use of a journal file that
+** is separate from the database file. The pager also implements file
+** locking to prevent two processes from writing the same database
+** file simultaneously, or one process from reading the database while
+** another is writing.
+**
+** @(#) $Id: pager.c,v 1.469 2008/08/02 03:50:39 drh Exp $
+*/
+#ifndef SQLITE_OMIT_DISKIO
+#include "sqliteInt.h"
+#include <assert.h>
+#include <string.h>
+
+/*
+** Macros for troubleshooting. Normally turned off
+*/
+#if 0
+#define sqlite3DebugPrintf printf
+#define PAGERTRACE1(X) sqlite3DebugPrintf(X)
+#define PAGERTRACE2(X,Y) sqlite3DebugPrintf(X,Y)
+#define PAGERTRACE3(X,Y,Z) sqlite3DebugPrintf(X,Y,Z)
+#define PAGERTRACE4(X,Y,Z,W) sqlite3DebugPrintf(X,Y,Z,W)
+#define PAGERTRACE5(X,Y,Z,W,V) sqlite3DebugPrintf(X,Y,Z,W,V)
+#else
+#define PAGERTRACE1(X)
+#define PAGERTRACE2(X,Y)
+#define PAGERTRACE3(X,Y,Z)
+#define PAGERTRACE4(X,Y,Z,W)
+#define PAGERTRACE5(X,Y,Z,W,V)
+#endif
+
+/*
+** The following two macros are used within the PAGERTRACEX() macros above
+** to print out file-descriptors.
+**
+** PAGERID() takes a pointer to a Pager struct as its argument. The
+** associated file-descriptor is returned. FILEHANDLEID() takes an sqlite3_file
+** struct as its argument.
+*/
+#define PAGERID(p) ((int)(p->fd))
+#define FILEHANDLEID(fd) ((int)fd)
+
+/*
+** The page cache as a whole is always in one of the following
+** states:
+**
+** PAGER_UNLOCK The page cache is not currently reading or
+** writing the database file. There is no
+** data held in memory. This is the initial
+** state.
+**
+** PAGER_SHARED The page cache is reading the database.
+** Writing is not permitted. There can be
+** multiple readers accessing the same database
+** file at the same time.
+**
+** PAGER_RESERVED This process has reserved the database for writing
+** but has not yet made any changes. Only one process
+** at a time can reserve the database. The original
+** database file has not been modified so other
+** processes may still be reading the on-disk
+** database file.
+**
+** PAGER_EXCLUSIVE The page cache is writing the database.
+** Access is exclusive. No other processes or
+** threads can be reading or writing while one
+** process is writing.
+**
+** PAGER_SYNCED The pager moves to this state from PAGER_EXCLUSIVE
+** after all dirty pages have been written to the
+** database file and the file has been synced to
+** disk. All that remains to do is to remove or
+** truncate the journal file and the transaction
+** will be committed.
+**
+** The page cache comes up in PAGER_UNLOCK. The first time a
+** sqlite3PagerGet() occurs, the state transitions to PAGER_SHARED.
+** After all pages have been released using sqlite_page_unref(),
+** the state transitions back to PAGER_UNLOCK. The first time
+** that sqlite3PagerWrite() is called, the state transitions to
+** PAGER_RESERVED. (Note that sqlite3PagerWrite() can only be
+** called on an outstanding page which means that the pager must
+** be in PAGER_SHARED before it transitions to PAGER_RESERVED.)
+** PAGER_RESERVED means that there is an open rollback journal.
+** The transition to PAGER_EXCLUSIVE occurs before any changes
+** are made to the database file, though writes to the rollback
+** journal occurs with just PAGER_RESERVED. After an sqlite3PagerRollback()
+** or sqlite3PagerCommitPhaseTwo(), the state can go back to PAGER_SHARED,
+** or it can stay at PAGER_EXCLUSIVE if we are in exclusive access mode.
+*/
+#define PAGER_UNLOCK 0
+#define PAGER_SHARED 1 /* same as SHARED_LOCK */
+#define PAGER_RESERVED 2 /* same as RESERVED_LOCK */
+#define PAGER_EXCLUSIVE 4 /* same as EXCLUSIVE_LOCK */
+#define PAGER_SYNCED 5
+
+/*
+** If the SQLITE_BUSY_RESERVED_LOCK macro is set to true at compile-time,
+** then failed attempts to get a reserved lock will invoke the busy callback.
+** This is off by default. To see why, consider the following scenario:
+**
+** Suppose thread A already has a shared lock and wants a reserved lock.
+** Thread B already has a reserved lock and wants an exclusive lock. If
+** both threads are using their busy callbacks, it might be a long time
+** be for one of the threads give up and allows the other to proceed.
+** But if the thread trying to get the reserved lock gives up quickly
+** (if it never invokes its busy callback) then the contention will be
+** resolved quickly.
+*/
+#ifndef SQLITE_BUSY_RESERVED_LOCK
+# define SQLITE_BUSY_RESERVED_LOCK 0
+#endif
+
+/*
+** This macro rounds values up so that if the value is an address it
+** is guaranteed to be an address that is aligned to an 8-byte boundary.
+*/
+#define FORCE_ALIGNMENT(X) (((X)+7)&~7)
+
+typedef struct PgHdr PgHdr;
+
+/*
+** Each pager stores all currently unreferenced pages in a list sorted
+** in least-recently-used (LRU) order (i.e. the first item on the list has
+** not been referenced in a long time, the last item has been recently
+** used). An instance of this structure is included as part of each
+** pager structure for this purpose (variable Pager.lru).
+**
+** Additionally, if memory-management is enabled, all unreferenced pages
+** are stored in a global LRU list (global variable sqlite3LruPageList).
+**
+** In both cases, the PagerLruList.pFirstSynced variable points to
+** the first page in the corresponding list that does not require an
+** fsync() operation before its memory can be reclaimed. If no such
+** page exists, PagerLruList.pFirstSynced is set to NULL.
+*/
+typedef struct PagerLruList PagerLruList;
+struct PagerLruList {
+ PgHdr *pFirst; /* First page in LRU list */
+ PgHdr *pLast; /* Last page in LRU list (the most recently used) */
+ PgHdr *pFirstSynced; /* First page in list with PgHdr.needSync==0 */
+};
+
+/*
+** The following structure contains the next and previous pointers used
+** to link a PgHdr structure into a PagerLruList linked list.
+*/
+typedef struct PagerLruLink PagerLruLink;
+struct PagerLruLink {
+ PgHdr *pNext;
+ PgHdr *pPrev;
+};
+
+/*
+** Each in-memory image of a page begins with the following header.
+** This header is only visible to this pager module. The client
+** code that calls pager sees only the data that follows the header.
+**
+** Client code should call sqlite3PagerWrite() on a page prior to making
+** any modifications to that page. The first time sqlite3PagerWrite()
+** is called, the original page contents are written into the rollback
+** journal and PgHdr.inJournal and PgHdr.needSync are set. Later, once
+** the journal page has made it onto the disk surface, PgHdr.needSync
+** is cleared. The modified page cannot be written back into the original
+** database file until the journal pages has been synced to disk and the
+** PgHdr.needSync has been cleared.
+**
+** The PgHdr.dirty flag is set when sqlite3PagerWrite() is called and
+** is cleared again when the page content is written back to the original
+** database file.
+**
+** Details of important structure elements:
+**
+** needSync
+**
+** If this is true, this means that it is not safe to write the page
+** content to the database because the original content needed
+** for rollback has not by synced to the main rollback journal.
+** The original content may have been written to the rollback journal
+** but it has not yet been synced. So we cannot write to the database
+** file because power failure might cause the page in the journal file
+** to never reach the disk. It is as if the write to the journal file
+** does not occur until the journal file is synced.
+**
+** This flag is false if the page content exactly matches what
+** currently exists in the database file. The needSync flag is also
+** false if the original content has been written to the main rollback
+** journal and synced. If the page represents a new page that has
+** been added onto the end of the database during the current
+** transaction, the needSync flag is true until the original database
+** size in the journal header has been synced to disk.
+**
+** inJournal
+**
+** This is true if the original page has been written into the main
+** rollback journal. This is always false for new pages added to
+** the end of the database file during the current transaction.
+** And this flag says nothing about whether or not the journal
+** has been synced to disk. For pages that are in the original
+** database file, the following expression should always be true:
+**
+** inJournal = sqlite3BitvecTest(pPager->pInJournal, pgno)
+**
+** The pPager->pInJournal object is only valid for the original
+** pages of the database, not new pages that are added to the end
+** of the database, so obviously the above expression cannot be
+** valid for new pages. For new pages inJournal is always 0.
+**
+** dirty
+**
+** When true, this means that the content of the page has been
+** modified and needs to be written back to the database file.
+** If false, it means that either the content of the page is
+** unchanged or else the content is unimportant and we do not
+** care whether or not it is preserved.
+**
+** alwaysRollback
+**
+** This means that the sqlite3PagerDontRollback() API should be
+** ignored for this page. The DontRollback() API attempts to say
+** that the content of the page on disk is unimportant (it is an
+** unused page on the freelist) so that it is unnecessary to
+** rollback changes to this page because the content of the page
+** can change without changing the meaning of the database. This
+** flag overrides any DontRollback() attempt. This flag is set
+** when a page that originally contained valid data is added to
+** the freelist. Later in the same transaction, this page might
+** be pulled from the freelist and reused for something different
+** and at that point the DontRollback() API will be called because
+** pages taken from the freelist do not need to be protected by
+** the rollback journal. But this flag says that the page was
+** not originally part of the freelist so that it still needs to
+** be rolled back in spite of any subsequent DontRollback() calls.
+**
+** needRead
+**
+** This flag means (when true) that the content of the page has
+** not yet been loaded from disk. The in-memory content is just
+** garbage. (Actually, we zero the content, but you should not
+** make any assumptions about the content nevertheless.) If the
+** content is needed in the future, it should be read from the
+** original database file.
+*/
+struct PgHdr {
+ Pager *pPager; /* The pager to which this page belongs */
+ Pgno pgno; /* The page number for this page */
+ PgHdr *pNextHash, *pPrevHash; /* Hash collision chain for PgHdr.pgno */
+ PagerLruLink free; /* Next and previous free pages */
+ PgHdr *pNextAll; /* A list of all pages */
+ u8 inJournal; /* TRUE if has been written to journal */
+ u8 dirty; /* TRUE if we need to write back changes */
+ u8 needSync; /* Sync journal before writing this page */
+ u8 alwaysRollback; /* Disable DontRollback() for this page */
+ u8 needRead; /* Read content if PagerWrite() is called */
+ short int nRef; /* Number of users of this page */
+ PgHdr *pDirty, *pPrevDirty; /* Dirty pages */
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ PgHdr *pPrevAll; /* A list of all pages */
+ PagerLruLink gfree; /* Global list of nRef==0 pages */
+#endif
+#ifdef SQLITE_CHECK_PAGES
+ u32 pageHash;
+#endif
+ void *pData; /* Page data */
+ /* Pager.nExtra bytes of local data appended to this header */
+};
+
+/*
+** For an in-memory only database, some extra information is recorded about
+** each page so that changes can be rolled back. (Journal files are not
+** used for in-memory databases.) The following information is added to
+** the end of every EXTRA block for in-memory databases.
+**
+** This information could have been added directly to the PgHdr structure.
+** But then it would take up an extra 8 bytes of storage on every PgHdr
+** even for disk-based databases. Splitting it out saves 8 bytes. This
+** is only a savings of 0.8% but those percentages add up.
+*/
+typedef struct PgHistory PgHistory;
+struct PgHistory {
+ u8 *pOrig; /* Original page text. Restore to this on a full rollback */
+ u8 *pStmt; /* Text as it was at the beginning of the current statement */
+ PgHdr *pNextStmt, *pPrevStmt; /* List of pages in the statement journal */
+ u8 inStmt; /* TRUE if in the statement subjournal */
+};
+
+/*
+** A macro used for invoking the codec if there is one
+*/
+#ifdef SQLITE_HAS_CODEC
+# define CODEC1(P,D,N,X) if( P->xCodec!=0 ){ P->xCodec(P->pCodecArg,D,N,X); }
+# define CODEC2(P,D,N,X) ((char*)(P->xCodec!=0?P->xCodec(P->pCodecArg,D,N,X):D))
+#else
+# define CODEC1(P,D,N,X) /* NO-OP */
+# define CODEC2(P,D,N,X) ((char*)D)
+#endif
+
+/*
+** Convert a pointer to a PgHdr into a pointer to its data
+** and back again.
+*/
+#define PGHDR_TO_DATA(P) ((P)->pData)
+#define PGHDR_TO_EXTRA(G,P) ((void*)&((G)[1]))
+#define PGHDR_TO_HIST(P,PGR) \
+ ((PgHistory*)&((char*)(&(P)[1]))[(PGR)->nExtra])
+
+/*
+** A open page cache is an instance of the following structure.
+**
+** Pager.errCode may be set to SQLITE_IOERR, SQLITE_CORRUPT, or
+** or SQLITE_FULL. Once one of the first three errors occurs, it persists
+** and is returned as the result of every major pager API call. The
+** SQLITE_FULL return code is slightly different. It persists only until the
+** next successful rollback is performed on the pager cache. Also,
+** SQLITE_FULL does not affect the sqlite3PagerGet() and sqlite3PagerLookup()
+** APIs, they may still be used successfully.
+*/
+struct Pager {
+ sqlite3_vfs *pVfs; /* OS functions to use for IO */
+ u8 journalOpen; /* True if journal file descriptors is valid */
+ u8 journalStarted; /* True if header of journal is synced */
+ u8 useJournal; /* Use a rollback journal on this file */
+ u8 noReadlock; /* Do not bother to obtain readlocks */
+ u8 stmtOpen; /* True if the statement subjournal is open */
+ u8 stmtInUse; /* True we are in a statement subtransaction */
+ u8 stmtAutoopen; /* Open stmt journal when main journal is opened*/
+ u8 noSync; /* Do not sync the journal if true */
+ u8 fullSync; /* Do extra syncs of the journal for robustness */
+ u8 sync_flags; /* One of SYNC_NORMAL or SYNC_FULL */
+ u8 state; /* PAGER_UNLOCK, _SHARED, _RESERVED, etc. */
+ u8 tempFile; /* zFilename is a temporary file */
+ u8 readOnly; /* True for a read-only database */
+ u8 needSync; /* True if an fsync() is needed on the journal */
+ u8 dirtyCache; /* True if cached pages have changed */
+ u8 alwaysRollback; /* Disable DontRollback() for all pages */
+ u8 memDb; /* True to inhibit all file I/O */
+ u8 setMaster; /* True if a m-j name has been written to jrnl */
+ u8 doNotSync; /* Boolean. While true, do not spill the cache */
+ u8 exclusiveMode; /* Boolean. True if locking_mode==EXCLUSIVE */
+ u8 journalMode; /* On of the PAGER_JOURNALMODE_* values */
+ u8 dbModified; /* True if there are any changes to the Db */
+ u8 changeCountDone; /* Set after incrementing the change-counter */
+ u32 vfsFlags; /* Flags for sqlite3_vfs.xOpen() */
+ int errCode; /* One of several kinds of errors */
+ int dbSize; /* Number of pages in the file */
+ int origDbSize; /* dbSize before the current change */
+ int stmtSize; /* Size of database (in pages) at stmt_begin() */
+ int nRec; /* Number of pages written to the journal */
+ u32 cksumInit; /* Quasi-random value added to every checksum */
+ int stmtNRec; /* Number of records in stmt subjournal */
+ int nExtra; /* Add this many bytes to each in-memory page */
+ int pageSize; /* Number of bytes in a page */
+ int nPage; /* Total number of in-memory pages */
+ int nRef; /* Number of in-memory pages with PgHdr.nRef>0 */
+ int mxPage; /* Maximum number of pages to hold in cache */
+ Pgno mxPgno; /* Maximum allowed size of the database */
+ Bitvec *pInJournal; /* One bit for each page in the database file */
+ Bitvec *pInStmt; /* One bit for each page in the database */
+ char *zFilename; /* Name of the database file */
+ char *zJournal; /* Name of the journal file */
+ char *zDirectory; /* Directory hold database and journal files */
+ sqlite3_file *fd, *jfd; /* File descriptors for database and journal */
+ sqlite3_file *stfd; /* File descriptor for the statement subjournal*/
+ BusyHandler *pBusyHandler; /* Pointer to sqlite.busyHandler */
+ PagerLruList lru; /* LRU list of free pages */
+ PgHdr *pAll; /* List of all pages */
+ PgHdr *pStmt; /* List of pages in the statement subjournal */
+ PgHdr *pDirty; /* List of all dirty pages */
+ i64 journalOff; /* Current byte offset in the journal file */
+ i64 journalHdr; /* Byte offset to previous journal header */
+ i64 stmtHdrOff; /* First journal header written this statement */
+ i64 stmtCksum; /* cksumInit when statement was started */
+ i64 stmtJSize; /* Size of journal at stmt_begin() */
+ int sectorSize; /* Assumed sector size during rollback */
+#ifdef SQLITE_TEST
+ int nHit, nMiss; /* Cache hits and missing */
+ int nRead, nWrite; /* Database pages read/written */
+#endif
+ void (*xDestructor)(DbPage*,int); /* Call this routine when freeing pages */
+ void (*xReiniter)(DbPage*,int); /* Call this routine when reloading pages */
+#ifdef SQLITE_HAS_CODEC
+ void *(*xCodec)(void*,void*,Pgno,int); /* Routine for en/decoding data */
+ void *pCodecArg; /* First argument to xCodec() */
+#endif
+ int nHash; /* Size of the pager hash table */
+ PgHdr **aHash; /* Hash table to map page number to PgHdr */
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ Pager *pNext; /* Doubly linked list of pagers on which */
+ Pager *pPrev; /* sqlite3_release_memory() will work */
+ volatile int iInUseMM; /* Non-zero if unavailable to MM */
+ volatile int iInUseDB; /* Non-zero if in sqlite3_release_memory() */
+#endif
+ char *pTmpSpace; /* Pager.pageSize bytes of space for tmp use */
+ char dbFileVers[16]; /* Changes whenever database file changes */
+ i64 journalSizeLimit; /* Size limit for persistent journal files */
+};
+
+/*
+** The following global variables hold counters used for
+** testing purposes only. These variables do not exist in
+** a non-testing build. These variables are not thread-safe.
+*/
+#ifdef SQLITE_TEST
+int sqlite3_pager_readdb_count = 0; /* Number of full pages read from DB */
+int sqlite3_pager_writedb_count = 0; /* Number of full pages written to DB */
+int sqlite3_pager_writej_count = 0; /* Number of pages written to journal */
+int sqlite3_pager_pgfree_count = 0; /* Number of cache pages freed */
+# define PAGER_INCR(v) v++
+#else
+# define PAGER_INCR(v)
+#endif
+
+/*
+** The following variable points to the head of a double-linked list
+** of all pagers that are eligible for page stealing by the
+** sqlite3_release_memory() interface. Access to this list is
+** protected by the SQLITE_MUTEX_STATIC_MEM2 mutex.
+*/
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+static Pager *sqlite3PagerList = 0;
+static PagerLruList sqlite3LruPageList = {0, 0, 0};
+#endif
+
+
+/*
+** Journal files begin with the following magic string. The data
+** was obtained from /dev/random. It is used only as a sanity check.
+**
+** Since version 2.8.0, the journal format contains additional sanity
+** checking information. If the power fails while the journal is begin
+** written, semi-random garbage data might appear in the journal
+** file after power is restored. If an attempt is then made
+** to roll the journal back, the database could be corrupted. The additional
+** sanity checking data is an attempt to discover the garbage in the
+** journal and ignore it.
+**
+** The sanity checking information for the new journal format consists
+** of a 32-bit checksum on each page of data. The checksum covers both
+** the page number and the pPager->pageSize bytes of data for the page.
+** This cksum is initialized to a 32-bit random value that appears in the
+** journal file right after the header. The random initializer is important,
+** because garbage data that appears at the end of a journal is likely
+** data that was once in other files that have now been deleted. If the
+** garbage data came from an obsolete journal file, the checksums might
+** be correct. But by initializing the checksum to random value which
+** is different for every journal, we minimize that risk.
+*/
+static const unsigned char aJournalMagic[] = {
+ 0xd9, 0xd5, 0x05, 0xf9, 0x20, 0xa1, 0x63, 0xd7,
+};
+
+/*
+** The size of the header and of each page in the journal is determined
+** by the following macros.
+*/
+#define JOURNAL_PG_SZ(pPager) ((pPager->pageSize) + 8)
+
+/*
+** The journal header size for this pager. In the future, this could be
+** set to some value read from the disk controller. The important
+** characteristic is that it is the same size as a disk sector.
+*/
+#define JOURNAL_HDR_SZ(pPager) (pPager->sectorSize)
+
+/*
+** The macro MEMDB is true if we are dealing with an in-memory database.
+** We do this as a macro so that if the SQLITE_OMIT_MEMORYDB macro is set,
+** the value of MEMDB will be a constant and the compiler will optimize
+** out code that would never execute.
+*/
+#ifdef SQLITE_OMIT_MEMORYDB
+# define MEMDB 0
+#else
+# define MEMDB pPager->memDb
+#endif
+
+/*
+** Page number PAGER_MJ_PGNO is never used in an SQLite database (it is
+** reserved for working around a windows/posix incompatibility). It is
+** used in the journal to signify that the remainder of the journal file
+** is devoted to storing a master journal name - there are no more pages to
+** roll back. See comments for function writeMasterJournal() for details.
+*/
+/* #define PAGER_MJ_PGNO(x) (PENDING_BYTE/((x)->pageSize)) */
+#define PAGER_MJ_PGNO(x) ((PENDING_BYTE/((x)->pageSize))+1)
+
+/*
+** The maximum legal page number is (2^31 - 1).
+*/
+#define PAGER_MAX_PGNO 2147483647
+
+/*
+** The pagerEnter() and pagerLeave() routines acquire and release
+** a mutex on each pager. The mutex is recursive.
+**
+** This is a special-purpose mutex. It only provides mutual exclusion
+** between the Btree and the Memory Management sqlite3_release_memory()
+** function. It does not prevent, for example, two Btrees from accessing
+** the same pager at the same time. Other general-purpose mutexes in
+** the btree layer handle that chore.
+*/
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ static void pagerEnter(Pager *p){
+ p->iInUseDB++;
+ if( p->iInUseMM && p->iInUseDB==1 ){
+#ifndef SQLITE_MUTEX_NOOP
+ sqlite3_mutex *mutex;
+ mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM2);
+#endif
+ p->iInUseDB = 0;
+ sqlite3_mutex_enter(mutex);
+ p->iInUseDB = 1;
+ sqlite3_mutex_leave(mutex);
+ }
+ assert( p->iInUseMM==0 );
+ }
+ static void pagerLeave(Pager *p){
+ p->iInUseDB--;
+ assert( p->iInUseDB>=0 );
+ }
+#else
+# define pagerEnter(X)
+# define pagerLeave(X)
+#endif
+
+/*
+** Add page pPg to the end of the linked list managed by structure
+** pList (pPg becomes the last entry in the list - the most recently
+** used). Argument pLink should point to either pPg->free or pPg->gfree,
+** depending on whether pPg is being added to the pager-specific or
+** global LRU list.
+*/
+static void listAdd(PagerLruList *pList, PagerLruLink *pLink, PgHdr *pPg){
+ pLink->pNext = 0;
+ pLink->pPrev = pList->pLast;
+
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ assert(pLink==&pPg->free || pLink==&pPg->gfree);
+ assert(pLink==&pPg->gfree || pList!=&sqlite3LruPageList);
+#endif
+
+ if( pList->pLast ){
+ int iOff = (char *)pLink - (char *)pPg;
+ PagerLruLink *pLastLink = (PagerLruLink *)(&((u8 *)pList->pLast)[iOff]);
+ pLastLink->pNext = pPg;
+ }else{
+ assert(!pList->pFirst);
+ pList->pFirst = pPg;
+ }
+
+ pList->pLast = pPg;
+ if( !pList->pFirstSynced && pPg->needSync==0 ){
+ pList->pFirstSynced = pPg;
+ }
+}
+
+/*
+** Remove pPg from the list managed by the structure pointed to by pList.
+**
+** Argument pLink should point to either pPg->free or pPg->gfree, depending
+** on whether pPg is being added to the pager-specific or global LRU list.
+*/
+static void listRemove(PagerLruList *pList, PagerLruLink *pLink, PgHdr *pPg){
+ int iOff = (char *)pLink - (char *)pPg;
+
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ assert(pLink==&pPg->free || pLink==&pPg->gfree);
+ assert(pLink==&pPg->gfree || pList!=&sqlite3LruPageList);
+#endif
+
+ if( pPg==pList->pFirst ){
+ pList->pFirst = pLink->pNext;
+ }
+ if( pPg==pList->pLast ){
+ pList->pLast = pLink->pPrev;
+ }
+ if( pLink->pPrev ){
+ PagerLruLink *pPrevLink = (PagerLruLink *)(&((u8 *)pLink->pPrev)[iOff]);
+ pPrevLink->pNext = pLink->pNext;
+ }
+ if( pLink->pNext ){
+ PagerLruLink *pNextLink = (PagerLruLink *)(&((u8 *)pLink->pNext)[iOff]);
+ pNextLink->pPrev = pLink->pPrev;
+ }
+ if( pPg==pList->pFirstSynced ){
+ PgHdr *p = pLink->pNext;
+ while( p && p->needSync ){
+ PagerLruLink *pL = (PagerLruLink *)(&((u8 *)p)[iOff]);
+ p = pL->pNext;
+ }
+ pList->pFirstSynced = p;
+ }
+
+ pLink->pNext = pLink->pPrev = 0;
+}
+
+/*
+** Add page pPg to the list of free pages for the pager. If
+** memory-management is enabled, also add the page to the global
+** list of free pages.
+*/
+static void lruListAdd(PgHdr *pPg){
+ listAdd(&pPg->pPager->lru, &pPg->free, pPg);
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ if( !pPg->pPager->memDb ){
+ sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU));
+ listAdd(&sqlite3LruPageList, &pPg->gfree, pPg);
+ sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU));
+ }
+#endif
+}
+
+/*
+** Remove page pPg from the list of free pages for the associated pager.
+** If memory-management is enabled, also remove pPg from the global list
+** of free pages.
+*/
+static void lruListRemove(PgHdr *pPg){
+ listRemove(&pPg->pPager->lru, &pPg->free, pPg);
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ if( !pPg->pPager->memDb ){
+ sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU));
+ listRemove(&sqlite3LruPageList, &pPg->gfree, pPg);
+ sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU));
+ }
+#endif
+}
+
+/*
+** This function is called just after the needSync flag has been cleared
+** from all pages managed by pPager (usually because the journal file
+** has just been synced). It updates the pPager->lru.pFirstSynced variable
+** and, if memory-management is enabled, the sqlite3LruPageList.pFirstSynced
+** variable also.
+*/
+static void lruListSetFirstSynced(Pager *pPager){
+ pPager->lru.pFirstSynced = pPager->lru.pFirst;
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ if( !pPager->memDb ){
+ PgHdr *p;
+ sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU));
+ for(p=sqlite3LruPageList.pFirst; p && p->needSync; p=p->gfree.pNext);
+ assert(p==pPager->lru.pFirstSynced || p==sqlite3LruPageList.pFirstSynced);
+ sqlite3LruPageList.pFirstSynced = p;
+ sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU));
+ }
+#endif
+}
+
+/*
+** Return true if page *pPg has already been written to the statement
+** journal (or statement snapshot has been created, if *pPg is part
+** of an in-memory database).
+*/
+static int pageInStatement(PgHdr *pPg){
+ Pager *pPager = pPg->pPager;
+ if( MEMDB ){
+ return PGHDR_TO_HIST(pPg, pPager)->inStmt;
+ }else{
+ return sqlite3BitvecTest(pPager->pInStmt, pPg->pgno);
+ }
+}
+
+/*
+** Change the size of the pager hash table to N. N must be a power
+** of two.
+*/
+static void pager_resize_hash_table(Pager *pPager, int N){
+ PgHdr **aHash, *pPg;
+ assert( N>0 && (N&(N-1))==0 );
+#ifdef SQLITE_MALLOC_SOFT_LIMIT
+ if( N*sizeof(aHash[0])>SQLITE_MALLOC_SOFT_LIMIT ){
+ N = SQLITE_MALLOC_SOFT_LIMIT/sizeof(aHash[0]);
+ }
+ if( N==pPager->nHash ) return;
+#endif
+ pagerLeave(pPager);
+ if( pPager->aHash!=0 ) sqlite3BeginBenignMalloc();
+ aHash = sqlite3MallocZero( sizeof(aHash[0])*N );
+ if( pPager->aHash!=0 ) sqlite3EndBenignMalloc();
+ pagerEnter(pPager);
+ if( aHash==0 ){
+ /* Failure to rehash is not an error. It is only a performance hit. */
+ return;
+ }
+ sqlite3_free(pPager->aHash);
+ pPager->nHash = N;
+ pPager->aHash = aHash;
+ for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
+ int h;
+ if( pPg->pgno==0 ){
+ assert( pPg->pNextHash==0 && pPg->pPrevHash==0 );
+ continue;
+ }
+ h = pPg->pgno & (N-1);
+ pPg->pNextHash = aHash[h];
+ if( aHash[h] ){
+ aHash[h]->pPrevHash = pPg;
+ }
+ aHash[h] = pPg;
+ pPg->pPrevHash = 0;
+ }
+}
+
+/*
+** Read a 32-bit integer from the given file descriptor. Store the integer
+** that is read in *pRes. Return SQLITE_OK if everything worked, or an
+** error code is something goes wrong.
+**
+** All values are stored on disk as big-endian.
+*/
+static int read32bits(sqlite3_file *fd, i64 offset, u32 *pRes){
+ unsigned char ac[4];
+ int rc = sqlite3OsRead(fd, ac, sizeof(ac), offset);
+ if( rc==SQLITE_OK ){
+ *pRes = sqlite3Get4byte(ac);
+ }
+ return rc;
+}
+
+/*
+** Write a 32-bit integer into a string buffer in big-endian byte order.
+*/
+#define put32bits(A,B) sqlite3Put4byte((u8*)A,B)
+
+/*
+** Write a 32-bit integer into the given file descriptor. Return SQLITE_OK
+** on success or an error code is something goes wrong.
+*/
+static int write32bits(sqlite3_file *fd, i64 offset, u32 val){
+ char ac[4];
+ put32bits(ac, val);
+ return sqlite3OsWrite(fd, ac, 4, offset);
+}
+
+/*
+** If file pFd is open, call sqlite3OsUnlock() on it.
+*/
+static int osUnlock(sqlite3_file *pFd, int eLock){
+ if( !pFd->pMethods ){
+ return SQLITE_OK;
+ }
+ return sqlite3OsUnlock(pFd, eLock);
+}
+
+/*
+** This function determines whether or not the atomic-write optimization
+** can be used with this pager. The optimization can be used if:
+**
+** (a) the value returned by OsDeviceCharacteristics() indicates that
+** a database page may be written atomically, and
+** (b) the value returned by OsSectorSize() is less than or equal
+** to the page size.
+**
+** If the optimization cannot be used, 0 is returned. If it can be used,
+** then the value returned is the size of the journal file when it
+** contains rollback data for exactly one page.
+*/
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+static int jrnlBufferSize(Pager *pPager){
+ int dc; /* Device characteristics */
+ int nSector; /* Sector size */
+ int szPage; /* Page size */
+ sqlite3_file *fd = pPager->fd;
+
+ if( fd->pMethods ){
+ dc = sqlite3OsDeviceCharacteristics(fd);
+ nSector = sqlite3OsSectorSize(fd);
+ szPage = pPager->pageSize;
+ }
+
+ assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
+ assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
+
+ if( !fd->pMethods ||
+ (dc & (SQLITE_IOCAP_ATOMIC|(szPage>>8)) && nSector<=szPage) ){
+ return JOURNAL_HDR_SZ(pPager) + JOURNAL_PG_SZ(pPager);
+ }
+ return 0;
+}
+#endif
+
+/*
+** This function should be called when an error occurs within the pager
+** code. The first argument is a pointer to the pager structure, the
+** second the error-code about to be returned by a pager API function.
+** The value returned is a copy of the second argument to this function.
+**
+** If the second argument is SQLITE_IOERR, SQLITE_CORRUPT, or SQLITE_FULL
+** the error becomes persistent. Until the persisten error is cleared,
+** subsequent API calls on this Pager will immediately return the same
+** error code.
+**
+** A persistent error indicates that the contents of the pager-cache
+** cannot be trusted. This state can be cleared by completely discarding
+** the contents of the pager-cache. If a transaction was active when
+** the persistent error occured, then the rollback journal may need
+** to be replayed.
+*/
+static void pager_unlock(Pager *pPager);
+static int pager_error(Pager *pPager, int rc){
+ int rc2 = rc & 0xff;
+ assert(
+ pPager->errCode==SQLITE_FULL ||
+ pPager->errCode==SQLITE_OK ||
+ (pPager->errCode & 0xff)==SQLITE_IOERR
+ );
+ if(
+ rc2==SQLITE_FULL ||
+ rc2==SQLITE_IOERR ||
+ rc2==SQLITE_CORRUPT
+ ){
+ pPager->errCode = rc;
+ if( pPager->state==PAGER_UNLOCK && pPager->nRef==0 ){
+ /* If the pager is already unlocked, call pager_unlock() now to
+ ** clear the error state and ensure that the pager-cache is
+ ** completely empty.
+ */
+ pager_unlock(pPager);
+ }
+ }
+ return rc;
+}
+
+/*
+** If SQLITE_CHECK_PAGES is defined then we do some sanity checking
+** on the cache using a hash function. This is used for testing
+** and debugging only.
+*/
+#ifdef SQLITE_CHECK_PAGES
+/*
+** Return a 32-bit hash of the page data for pPage.
+*/
+static u32 pager_datahash(int nByte, unsigned char *pData){
+ u32 hash = 0;
+ int i;
+ for(i=0; i<nByte; i++){
+ hash = (hash*1039) + pData[i];
+ }
+ return hash;
+}
+static u32 pager_pagehash(PgHdr *pPage){
+ return pager_datahash(pPage->pPager->pageSize,
+ (unsigned char *)PGHDR_TO_DATA(pPage));
+}
+
+/*
+** The CHECK_PAGE macro takes a PgHdr* as an argument. If SQLITE_CHECK_PAGES
+** is defined, and NDEBUG is not defined, an assert() statement checks
+** that the page is either dirty or still matches the calculated page-hash.
+*/
+#define CHECK_PAGE(x) checkPage(x)
+static void checkPage(PgHdr *pPg){
+ Pager *pPager = pPg->pPager;
+ assert( !pPg->pageHash || pPager->errCode || MEMDB || pPg->dirty ||
+ pPg->pageHash==pager_pagehash(pPg) );
+}
+
+#else
+#define pager_datahash(X,Y) 0
+#define pager_pagehash(X) 0
+#define CHECK_PAGE(x)
+#endif
+
+/*
+** When this is called the journal file for pager pPager must be open.
+** The master journal file name is read from the end of the file and
+** written into memory supplied by the caller.
+**
+** zMaster must point to a buffer of at least nMaster bytes allocated by
+** the caller. This should be sqlite3_vfs.mxPathname+1 (to ensure there is
+** enough space to write the master journal name). If the master journal
+** name in the journal is longer than nMaster bytes (including a
+** nul-terminator), then this is handled as if no master journal name
+** were present in the journal.
+**
+** If no master journal file name is present zMaster[0] is set to 0 and
+** SQLITE_OK returned.
+*/
+static int readMasterJournal(sqlite3_file *pJrnl, char *zMaster, int nMaster){
+ int rc;
+ u32 len;
+ i64 szJ;
+ u32 cksum;
+ u32 u; /* Unsigned loop counter */
+ unsigned char aMagic[8]; /* A buffer to hold the magic header */
+
+ zMaster[0] = '\0';
+
+ rc = sqlite3OsFileSize(pJrnl, &szJ);
+ if( rc!=SQLITE_OK || szJ<16 ) return rc;
+
+ rc = read32bits(pJrnl, szJ-16, &len);
+ if( rc!=SQLITE_OK ) return rc;
+
+ if( len>=nMaster ){
+ return SQLITE_OK;
+ }
+
+ rc = read32bits(pJrnl, szJ-12, &cksum);
+ if( rc!=SQLITE_OK ) return rc;
+
+ rc = sqlite3OsRead(pJrnl, aMagic, 8, szJ-8);
+ if( rc!=SQLITE_OK || memcmp(aMagic, aJournalMagic, 8) ) return rc;
+
+ rc = sqlite3OsRead(pJrnl, zMaster, len, szJ-16-len);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ zMaster[len] = '\0';
+
+ /* See if the checksum matches the master journal name */
+ for(u=0; u<len; u++){
+ cksum -= zMaster[u];
+ }
+ if( cksum ){
+ /* If the checksum doesn't add up, then one or more of the disk sectors
+ ** containing the master journal filename is corrupted. This means
+ ** definitely roll back, so just return SQLITE_OK and report a (nul)
+ ** master-journal filename.
+ */
+ zMaster[0] = '\0';
+ }
+
+ return SQLITE_OK;
+}
+
+/*
+** Seek the journal file descriptor to the next sector boundary where a
+** journal header may be read or written. Pager.journalOff is updated with
+** the new seek offset.
+**
+** i.e for a sector size of 512:
+**
+** Input Offset Output Offset
+** ---------------------------------------
+** 0 0
+** 512 512
+** 100 512
+** 2000 2048
+**
+*/
+static void seekJournalHdr(Pager *pPager){
+ i64 offset = 0;
+ i64 c = pPager->journalOff;
+ if( c ){
+ offset = ((c-1)/JOURNAL_HDR_SZ(pPager) + 1) * JOURNAL_HDR_SZ(pPager);
+ }
+ assert( offset%JOURNAL_HDR_SZ(pPager)==0 );
+ assert( offset>=c );
+ assert( (offset-c)<JOURNAL_HDR_SZ(pPager) );
+ pPager->journalOff = offset;
+}
+
+/*
+** Write zeros over the header of the journal file. This has the
+** effect of invalidating the journal file and committing the
+** transaction.
+*/
+static int zeroJournalHdr(Pager *pPager, int doTruncate){
+ int rc = SQLITE_OK;
+ static const char zeroHdr[28];
+
+ if( pPager->journalOff ){
+ i64 iLimit = pPager->journalSizeLimit;
+
+ IOTRACE(("JZEROHDR %p\n", pPager))
+ if( doTruncate || iLimit==0 ){
+ rc = sqlite3OsTruncate(pPager->jfd, 0);
+ }else{
+ rc = sqlite3OsWrite(pPager->jfd, zeroHdr, sizeof(zeroHdr), 0);
+ }
+ if( rc==SQLITE_OK && !pPager->noSync ){
+ rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_DATAONLY|pPager->sync_flags);
+ }
+
+ /* At this point the transaction is committed but the write lock
+ ** is still held on the file. If there is a size limit configured for
+ ** the persistent journal and the journal file currently consumes more
+ ** space than that limit allows for, truncate it now. There is no need
+ ** to sync the file following this operation.
+ */
+ if( rc==SQLITE_OK && iLimit>0 ){
+ i64 sz;
+ rc = sqlite3OsFileSize(pPager->jfd, &sz);
+ if( rc==SQLITE_OK && sz>iLimit ){
+ rc = sqlite3OsTruncate(pPager->jfd, iLimit);
+ }
+ }
+ }
+ return rc;
+}
+
+/*
+** The journal file must be open when this routine is called. A journal
+** header (JOURNAL_HDR_SZ bytes) is written into the journal file at the
+** current location.
+**
+** The format for the journal header is as follows:
+** - 8 bytes: Magic identifying journal format.
+** - 4 bytes: Number of records in journal, or -1 no-sync mode is on.
+** - 4 bytes: Random number used for page hash.
+** - 4 bytes: Initial database page count.
+** - 4 bytes: Sector size used by the process that wrote this journal.
+** - 4 bytes: Database page size.
+**
+** Followed by (JOURNAL_HDR_SZ - 28) bytes of unused space.
+*/
+static int writeJournalHdr(Pager *pPager){
+ int rc = SQLITE_OK;
+ char *zHeader = pPager->pTmpSpace;
+ int nHeader = pPager->pageSize;
+ int nWrite;
+
+ if( nHeader>JOURNAL_HDR_SZ(pPager) ){
+ nHeader = JOURNAL_HDR_SZ(pPager);
+ }
+
+ if( pPager->stmtHdrOff==0 ){
+ pPager->stmtHdrOff = pPager->journalOff;
+ }
+
+ seekJournalHdr(pPager);
+ pPager->journalHdr = pPager->journalOff;
+
+ memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
+
+ /*
+ ** Write the nRec Field - the number of page records that follow this
+ ** journal header. Normally, zero is written to this value at this time.
+ ** After the records are added to the journal (and the journal synced,
+ ** if in full-sync mode), the zero is overwritten with the true number
+ ** of records (see syncJournal()).
+ **
+ ** A faster alternative is to write 0xFFFFFFFF to the nRec field. When
+ ** reading the journal this value tells SQLite to assume that the
+ ** rest of the journal file contains valid page records. This assumption
+ ** is dangerous, as if a failure occured whilst writing to the journal
+ ** file it may contain some garbage data. There are two scenarios
+ ** where this risk can be ignored:
+ **
+ ** * When the pager is in no-sync mode. Corruption can follow a
+ ** power failure in this case anyway.
+ **
+ ** * When the SQLITE_IOCAP_SAFE_APPEND flag is set. This guarantees
+ ** that garbage data is never appended to the journal file.
+ */
+ assert(pPager->fd->pMethods||pPager->noSync);
+ if( (pPager->noSync)
+ || (sqlite3OsDeviceCharacteristics(pPager->fd)&SQLITE_IOCAP_SAFE_APPEND)
+ ){
+ put32bits(&zHeader[sizeof(aJournalMagic)], 0xffffffff);
+ }else{
+ put32bits(&zHeader[sizeof(aJournalMagic)], 0);
+ }
+
+ /* The random check-hash initialiser */
+ sqlite3_randomness(sizeof(pPager->cksumInit), &pPager->cksumInit);
+ put32bits(&zHeader[sizeof(aJournalMagic)+4], pPager->cksumInit);
+ /* The initial database size */
+ put32bits(&zHeader[sizeof(aJournalMagic)+8], pPager->dbSize);
+ /* The assumed sector size for this process */
+ put32bits(&zHeader[sizeof(aJournalMagic)+12], pPager->sectorSize);
+ if( pPager->journalHdr==0 ){
+ /* The page size */
+ put32bits(&zHeader[sizeof(aJournalMagic)+16], pPager->pageSize);
+ }
+
+ for(nWrite=0; rc==SQLITE_OK&&nWrite<JOURNAL_HDR_SZ(pPager); nWrite+=nHeader){
+ IOTRACE(("JHDR %p %lld %d\n", pPager, pPager->journalHdr, nHeader))
+ rc = sqlite3OsWrite(pPager->jfd, zHeader, nHeader, pPager->journalOff);
+ pPager->journalOff += nHeader;
+ }
+
+ return rc;
+}
+
+/*
+** The journal file must be open when this is called. A journal header file
+** (JOURNAL_HDR_SZ bytes) is read from the current location in the journal
+** file. See comments above function writeJournalHdr() for a description of
+** the journal header format.
+**
+** If the header is read successfully, *nRec is set to the number of
+** page records following this header and *dbSize is set to the size of the
+** database before the transaction began, in pages. Also, pPager->cksumInit
+** is set to the value read from the journal header. SQLITE_OK is returned
+** in this case.
+**
+** If the journal header file appears to be corrupted, SQLITE_DONE is
+** returned and *nRec and *dbSize are not set. If JOURNAL_HDR_SZ bytes
+** cannot be read from the journal file an error code is returned.
+*/
+static int readJournalHdr(
+ Pager *pPager,
+ i64 journalSize,
+ u32 *pNRec,
+ u32 *pDbSize
+){
+ int rc;
+ unsigned char aMagic[8]; /* A buffer to hold the magic header */
+ i64 jrnlOff;
+ int iPageSize;
+
+ seekJournalHdr(pPager);
+ if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){
+ return SQLITE_DONE;
+ }
+ jrnlOff = pPager->journalOff;
+
+ rc = sqlite3OsRead(pPager->jfd, aMagic, sizeof(aMagic), jrnlOff);
+ if( rc ) return rc;
+ jrnlOff += sizeof(aMagic);
+
+ if( memcmp(aMagic, aJournalMagic, sizeof(aMagic))!=0 ){
+ return SQLITE_DONE;
+ }
+
+ rc = read32bits(pPager->jfd, jrnlOff, pNRec);
+ if( rc ) return rc;
+
+ rc = read32bits(pPager->jfd, jrnlOff+4, &pPager->cksumInit);
+ if( rc ) return rc;
+
+ rc = read32bits(pPager->jfd, jrnlOff+8, pDbSize);
+ if( rc ) return rc;
+
+ rc = read32bits(pPager->jfd, jrnlOff+16, (u32 *)&iPageSize);
+ if( rc==SQLITE_OK
+ && iPageSize>=512
+ && iPageSize<=SQLITE_MAX_PAGE_SIZE
+ && ((iPageSize-1)&iPageSize)==0
+ ){
+ u16 pagesize = iPageSize;
+ rc = sqlite3PagerSetPagesize(pPager, &pagesize);
+ }
+ if( rc ) return rc;
+
+ /* Update the assumed sector-size to match the value used by
+ ** the process that created this journal. If this journal was
+ ** created by a process other than this one, then this routine
+ ** is being called from within pager_playback(). The local value
+ ** of Pager.sectorSize is restored at the end of that routine.
+ */
+ rc = read32bits(pPager->jfd, jrnlOff+12, (u32 *)&pPager->sectorSize);
+ if( rc ) return rc;
+
+ pPager->journalOff += JOURNAL_HDR_SZ(pPager);
+ return SQLITE_OK;
+}
+
+
+/*
+** Write the supplied master journal name into the journal file for pager
+** pPager at the current location. The master journal name must be the last
+** thing written to a journal file. If the pager is in full-sync mode, the
+** journal file descriptor is advanced to the next sector boundary before
+** anything is written. The format is:
+**
+** + 4 bytes: PAGER_MJ_PGNO.
+** + N bytes: length of master journal name.
+** + 4 bytes: N
+** + 4 bytes: Master journal name checksum.
+** + 8 bytes: aJournalMagic[].
+**
+** The master journal page checksum is the sum of the bytes in the master
+** journal name.
+**
+** If zMaster is a NULL pointer (occurs for a single database transaction),
+** this call is a no-op.
+*/
+static int writeMasterJournal(Pager *pPager, const char *zMaster){
+ int rc;
+ int len;
+ int i;
+ i64 jrnlOff;
+ i64 jrnlSize;
+ u32 cksum = 0;
+ char zBuf[sizeof(aJournalMagic)+2*4];
+
+ if( !zMaster || pPager->setMaster) return SQLITE_OK;
+ pPager->setMaster = 1;
+
+ len = strlen(zMaster);
+ for(i=0; i<len; i++){
+ cksum += zMaster[i];
+ }
+
+ /* If in full-sync mode, advance to the next disk sector before writing
+ ** the master journal name. This is in case the previous page written to
+ ** the journal has already been synced.
+ */
+ if( pPager->fullSync ){
+ seekJournalHdr(pPager);
+ }
+ jrnlOff = pPager->journalOff;
+ pPager->journalOff += (len+20);
+
+ rc = write32bits(pPager->jfd, jrnlOff, PAGER_MJ_PGNO(pPager));
+ if( rc!=SQLITE_OK ) return rc;
+ jrnlOff += 4;
+
+ rc = sqlite3OsWrite(pPager->jfd, zMaster, len, jrnlOff);
+ if( rc!=SQLITE_OK ) return rc;
+ jrnlOff += len;
+
+ put32bits(zBuf, len);
+ put32bits(&zBuf[4], cksum);
+ memcpy(&zBuf[8], aJournalMagic, sizeof(aJournalMagic));
+ rc = sqlite3OsWrite(pPager->jfd, zBuf, 8+sizeof(aJournalMagic), jrnlOff);
+ jrnlOff += 8+sizeof(aJournalMagic);
+ pPager->needSync = !pPager->noSync;
+
+ /* If the pager is in peristent-journal mode, then the physical
+ ** journal-file may extend past the end of the master-journal name
+ ** and 8 bytes of magic data just written to the file. This is
+ ** dangerous because the code to rollback a hot-journal file
+ ** will not be able to find the master-journal name to determine
+ ** whether or not the journal is hot.
+ **
+ ** Easiest thing to do in this scenario is to truncate the journal
+ ** file to the required size.
+ */
+ if( (rc==SQLITE_OK)
+ && (rc = sqlite3OsFileSize(pPager->jfd, &jrnlSize))==SQLITE_OK
+ && jrnlSize>jrnlOff
+ ){
+ rc = sqlite3OsTruncate(pPager->jfd, jrnlOff);
+ }
+ return rc;
+}
+
+/*
+** Add or remove a page from the list of all pages that are in the
+** statement journal.
+**
+** The Pager keeps a separate list of pages that are currently in
+** the statement journal. This helps the sqlite3PagerStmtCommit()
+** routine run MUCH faster for the common case where there are many
+** pages in memory but only a few are in the statement journal.
+*/
+static void page_add_to_stmt_list(PgHdr *pPg){
+ Pager *pPager = pPg->pPager;
+ PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager);
+ assert( MEMDB );
+ if( !pHist->inStmt ){
+ assert( pHist->pPrevStmt==0 && pHist->pNextStmt==0 );
+ if( pPager->pStmt ){
+ PGHDR_TO_HIST(pPager->pStmt, pPager)->pPrevStmt = pPg;
+ }
+ pHist->pNextStmt = pPager->pStmt;
+ pPager->pStmt = pPg;
+ pHist->inStmt = 1;
+ }
+}
+
+/*
+** Find a page in the hash table given its page number. Return
+** a pointer to the page or NULL if not found.
+*/
+static PgHdr *pager_lookup(Pager *pPager, Pgno pgno){
+ PgHdr *p;
+ if( pPager->aHash==0 ) return 0;
+ p = pPager->aHash[pgno & (pPager->nHash-1)];
+ while( p && p->pgno!=pgno ){
+ p = p->pNextHash;
+ }
+ return p;
+}
+
+/*
+** Clear the in-memory cache. This routine
+** sets the state of the pager back to what it was when it was first
+** opened. Any outstanding pages are invalidated and subsequent attempts
+** to access those pages will likely result in a coredump.
+*/
+static void pager_reset(Pager *pPager){
+ PgHdr *pPg, *pNext;
+ if( pPager->errCode ) return;
+ for(pPg=pPager->pAll; pPg; pPg=pNext){
+ IOTRACE(("PGFREE %p %d\n", pPager, pPg->pgno));
+ PAGER_INCR(sqlite3_pager_pgfree_count);
+ pNext = pPg->pNextAll;
+ lruListRemove(pPg);
+ sqlite3PageFree(pPg->pData);
+ sqlite3_free(pPg);
+ }
+ assert(pPager->lru.pFirst==0);
+ assert(pPager->lru.pFirstSynced==0);
+ assert(pPager->lru.pLast==0);
+ pPager->pStmt = 0;
+ pPager->pAll = 0;
+ pPager->pDirty = 0;
+ pPager->nHash = 0;
+ sqlite3_free(pPager->aHash);
+ pPager->nPage = 0;
+ pPager->aHash = 0;
+ pPager->nRef = 0;
+}
+
+/*
+** Unlock the database file.
+**
+** If the pager is currently in error state, discard the contents of
+** the cache and reset the Pager structure internal state. If there is
+** an open journal-file, then the next time a shared-lock is obtained
+** on the pager file (by this or any other process), it will be
+** treated as a hot-journal and rolled back.
+*/
+static void pager_unlock(Pager *pPager){
+ if( !pPager->exclusiveMode ){
+ if( !MEMDB ){
+ int rc = osUnlock(pPager->fd, NO_LOCK);
+ if( rc ) pPager->errCode = rc;
+ pPager->dbSize = -1;
+ IOTRACE(("UNLOCK %p\n", pPager))
+
+ /* Always close the journal file when dropping the database lock.
+ ** Otherwise, another connection with journal_mode=delete might
+ ** delete the file out from under us.
+ */
+ if( pPager->journalOpen ){
+ sqlite3OsClose(pPager->jfd);
+ pPager->journalOpen = 0;
+ sqlite3BitvecDestroy(pPager->pInJournal);
+ pPager->pInJournal = 0;
+ }
+
+ /* If Pager.errCode is set, the contents of the pager cache cannot be
+ ** trusted. Now that the pager file is unlocked, the contents of the
+ ** cache can be discarded and the error code safely cleared.
+ */
+ if( pPager->errCode ){
+ if( rc==SQLITE_OK ) pPager->errCode = SQLITE_OK;
+ pager_reset(pPager);
+ if( pPager->stmtOpen ){
+ sqlite3OsClose(pPager->stfd);
+ sqlite3BitvecDestroy(pPager->pInStmt);
+ pPager->pInStmt = 0;
+ }
+ pPager->stmtOpen = 0;
+ pPager->stmtInUse = 0;
+ pPager->journalOff = 0;
+ pPager->journalStarted = 0;
+ pPager->stmtAutoopen = 0;
+ pPager->origDbSize = 0;
+ }
+ }
+
+ if( !MEMDB || pPager->errCode==SQLITE_OK ){
+ pPager->state = PAGER_UNLOCK;
+ pPager->changeCountDone = 0;
+ }
+ }
+}
+
+/*
+** Execute a rollback if a transaction is active and unlock the
+** database file. If the pager has already entered the error state,
+** do not attempt the rollback.
+*/
+static void pagerUnlockAndRollback(Pager *p){
+ /* assert( p->state>=PAGER_RESERVED || p->journalOpen==0 ); */
+ if( p->errCode==SQLITE_OK && p->state>=PAGER_RESERVED ){
+ sqlite3BeginBenignMalloc();
+ sqlite3PagerRollback(p);
+ sqlite3EndBenignMalloc();
+ }
+ pager_unlock(p);
+#if 0
+ assert( p->errCode || !p->journalOpen || (p->exclusiveMode&&!p->journalOff) );
+ assert( p->errCode || !p->stmtOpen || p->exclusiveMode );
+#endif
+}
+
+/*
+** This routine ends a transaction. A transaction is ended by either
+** a COMMIT or a ROLLBACK.
+**
+** When this routine is called, the pager has the journal file open and
+** a RESERVED or EXCLUSIVE lock on the database. This routine will release
+** the database lock and acquires a SHARED lock in its place if that is
+** the appropriate thing to do. Release locks usually is appropriate,
+** unless we are in exclusive access mode or unless this is a
+** COMMIT AND BEGIN or ROLLBACK AND BEGIN operation.
+**
+** The journal file is either deleted or truncated.
+**
+** TODO: Consider keeping the journal file open for temporary databases.
+** This might give a performance improvement on windows where opening
+** a file is an expensive operation.
+*/
+static int pager_end_transaction(Pager *pPager, int hasMaster){
+ PgHdr *pPg;
+ int rc = SQLITE_OK;
+ int rc2 = SQLITE_OK;
+ assert( !MEMDB );
+ if( pPager->state<PAGER_RESERVED ){
+ return SQLITE_OK;
+ }
+ sqlite3PagerStmtCommit(pPager);
+ if( pPager->stmtOpen && !pPager->exclusiveMode ){
+ sqlite3OsClose(pPager->stfd);
+ pPager->stmtOpen = 0;
+ }
+ if( pPager->journalOpen ){
+ if( pPager->exclusiveMode
+ || pPager->journalMode==PAGER_JOURNALMODE_PERSIST
+ ){
+ rc = zeroJournalHdr(pPager, hasMaster);
+ pager_error(pPager, rc);
+ pPager->journalOff = 0;
+ pPager->journalStarted = 0;
+ }else{
+ sqlite3OsClose(pPager->jfd);
+ pPager->journalOpen = 0;
+ if( rc==SQLITE_OK && !pPager->tempFile ){
+ rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
+ }
+ }
+ sqlite3BitvecDestroy(pPager->pInJournal);
+ pPager->pInJournal = 0;
+ for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
+ pPg->inJournal = 0;
+ pPg->dirty = 0;
+ pPg->needSync = 0;
+ pPg->alwaysRollback = 0;
+#ifdef SQLITE_CHECK_PAGES
+ pPg->pageHash = pager_pagehash(pPg);
+#endif
+ }
+ pPager->pDirty = 0;
+ pPager->dirtyCache = 0;
+ pPager->nRec = 0;
+ }else{
+ assert( pPager->pInJournal==0 );
+ }
+
+ if( !pPager->exclusiveMode ){
+ rc2 = osUnlock(pPager->fd, SHARED_LOCK);
+ pPager->state = PAGER_SHARED;
+ }else if( pPager->state==PAGER_SYNCED ){
+ pPager->state = PAGER_EXCLUSIVE;
+ }
+ pPager->origDbSize = 0;
+ pPager->setMaster = 0;
+ pPager->needSync = 0;
+ lruListSetFirstSynced(pPager);
+ pPager->dbSize = -1;
+ pPager->dbModified = 0;
+
+ return (rc==SQLITE_OK?rc2:rc);
+}
+
+/*
+** Compute and return a checksum for the page of data.
+**
+** This is not a real checksum. It is really just the sum of the
+** random initial value and the page number. We experimented with
+** a checksum of the entire data, but that was found to be too slow.
+**
+** Note that the page number is stored at the beginning of data and
+** the checksum is stored at the end. This is important. If journal
+** corruption occurs due to a power failure, the most likely scenario
+** is that one end or the other of the record will be changed. It is
+** much less likely that the two ends of the journal record will be
+** correct and the middle be corrupt. Thus, this "checksum" scheme,
+** though fast and simple, catches the mostly likely kind of corruption.
+**
+** FIX ME: Consider adding every 200th (or so) byte of the data to the
+** checksum. That way if a single page spans 3 or more disk sectors and
+** only the middle sector is corrupt, we will still have a reasonable
+** chance of failing the checksum and thus detecting the problem.
+*/
+static u32 pager_cksum(Pager *pPager, const u8 *aData){
+ u32 cksum = pPager->cksumInit;
+ int i = pPager->pageSize-200;
+ while( i>0 ){
+ cksum += aData[i];
+ i -= 200;
+ }
+ return cksum;
+}
+
+/* Forward declaration */
+static void makeClean(PgHdr*);
+
+/*
+** Read a single page from the journal file opened on file descriptor
+** jfd. Playback this one page.
+**
+** If useCksum==0 it means this journal does not use checksums. Checksums
+** are not used in statement journals because statement journals do not
+** need to survive power failures.
+*/
+static int pager_playback_one_page(
+ Pager *pPager,
+ sqlite3_file *jfd,
+ i64 offset,
+ int useCksum
+){
+ int rc;
+ PgHdr *pPg; /* An existing page in the cache */
+ Pgno pgno; /* The page number of a page in journal */
+ u32 cksum; /* Checksum used for sanity checking */
+ u8 *aData = (u8 *)pPager->pTmpSpace; /* Temp storage for a page */
+
+ /* useCksum should be true for the main journal and false for
+ ** statement journals. Verify that this is always the case
+ */
+ assert( jfd == (useCksum ? pPager->jfd : pPager->stfd) );
+ assert( aData );
+
+ rc = read32bits(jfd, offset, &pgno);
+ if( rc!=SQLITE_OK ) return rc;
+ rc = sqlite3OsRead(jfd, aData, pPager->pageSize, offset+4);
+ if( rc!=SQLITE_OK ) return rc;
+ pPager->journalOff += pPager->pageSize + 4;
+
+ /* Sanity checking on the page. This is more important that I originally
+ ** thought. If a power failure occurs while the journal is being written,
+ ** it could cause invalid data to be written into the journal. We need to
+ ** detect this invalid data (with high probability) and ignore it.
+ */
+ if( pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){
+ return SQLITE_DONE;
+ }
+ if( pgno>(unsigned)pPager->dbSize ){
+ return SQLITE_OK;
+ }
+ if( useCksum ){
+ rc = read32bits(jfd, offset+pPager->pageSize+4, &cksum);
+ if( rc ) return rc;
+ pPager->journalOff += 4;
+ if( pager_cksum(pPager, aData)!=cksum ){
+ return SQLITE_DONE;
+ }
+ }
+
+ assert( pPager->state==PAGER_RESERVED || pPager->state>=PAGER_EXCLUSIVE );
+
+ /* If the pager is in RESERVED state, then there must be a copy of this
+ ** page in the pager cache. In this case just update the pager cache,
+ ** not the database file. The page is left marked dirty in this case.
+ **
+ ** An exception to the above rule: If the database is in no-sync mode
+ ** and a page is moved during an incremental vacuum then the page may
+ ** not be in the pager cache. Later: if a malloc() or IO error occurs
+ ** during a Movepage() call, then the page may not be in the cache
+ ** either. So the condition described in the above paragraph is not
+ ** assert()able.
+ **
+ ** If in EXCLUSIVE state, then we update the pager cache if it exists
+ ** and the main file. The page is then marked not dirty.
+ **
+ ** Ticket #1171: The statement journal might contain page content that is
+ ** different from the page content at the start of the transaction.
+ ** This occurs when a page is changed prior to the start of a statement
+ ** then changed again within the statement. When rolling back such a
+ ** statement we must not write to the original database unless we know
+ ** for certain that original page contents are synced into the main rollback
+ ** journal. Otherwise, a power loss might leave modified data in the
+ ** database file without an entry in the rollback journal that can
+ ** restore the database to its original form. Two conditions must be
+ ** met before writing to the database files. (1) the database must be
+ ** locked. (2) we know that the original page content is fully synced
+ ** in the main journal either because the page is not in cache or else
+ ** the page is marked as needSync==0.
+ **
+ ** 2008-04-14: When attempting to vacuum a corrupt database file, it
+ ** is possible to fail a statement on a database that does not yet exist.
+ ** Do not attempt to write if database file has never been opened.
+ */
+ pPg = pager_lookup(pPager, pgno);
+ PAGERTRACE4("PLAYBACK %d page %d hash(%08x)\n",
+ PAGERID(pPager), pgno, pager_datahash(pPager->pageSize, aData));
+ if( pPager->state>=PAGER_EXCLUSIVE && (pPg==0 || pPg->needSync==0)
+ && pPager->fd->pMethods ){
+ i64 offset = (pgno-1)*(i64)pPager->pageSize;
+ rc = sqlite3OsWrite(pPager->fd, aData, pPager->pageSize, offset);
+ if( pPg ){
+ makeClean(pPg);
+ }
+ }
+ if( pPg ){
+ /* No page should ever be explicitly rolled back that is in use, except
+ ** for page 1 which is held in use in order to keep the lock on the
+ ** database active. However such a page may be rolled back as a result
+ ** of an internal error resulting in an automatic call to
+ ** sqlite3PagerRollback().
+ */
+ void *pData;
+ /* assert( pPg->nRef==0 || pPg->pgno==1 ); */
+ pData = PGHDR_TO_DATA(pPg);
+ memcpy(pData, aData, pPager->pageSize);
+ if( pPager->xReiniter ){
+ pPager->xReiniter(pPg, pPager->pageSize);
+ }
+#ifdef SQLITE_CHECK_PAGES
+ pPg->pageHash = pager_pagehash(pPg);
+#endif
+ /* If this was page 1, then restore the value of Pager.dbFileVers.
+ ** Do this before any decoding. */
+ if( pgno==1 ){
+ memcpy(&pPager->dbFileVers, &((u8*)pData)[24],sizeof(pPager->dbFileVers));
+ }
+
+ /* Decode the page just read from disk */
+ CODEC1(pPager, pData, pPg->pgno, 3);
+ }
+ return rc;
+}
+
+/*
+** Parameter zMaster is the name of a master journal file. A single journal
+** file that referred to the master journal file has just been rolled back.
+** This routine checks if it is possible to delete the master journal file,
+** and does so if it is.
+**
+** Argument zMaster may point to Pager.pTmpSpace. So that buffer is not
+** available for use within this function.
+**
+**
+** The master journal file contains the names of all child journals.
+** To tell if a master journal can be deleted, check to each of the
+** children. If all children are either missing or do not refer to
+** a different master journal, then this master journal can be deleted.
+*/
+static int pager_delmaster(Pager *pPager, const char *zMaster){
+ sqlite3_vfs *pVfs = pPager->pVfs;
+ int rc;
+ int master_open = 0;
+ sqlite3_file *pMaster;
+ sqlite3_file *pJournal;
+ char *zMasterJournal = 0; /* Contents of master journal file */
+ i64 nMasterJournal; /* Size of master journal file */
+
+ /* Open the master journal file exclusively in case some other process
+ ** is running this routine also. Not that it makes too much difference.
+ */
+ pMaster = (sqlite3_file *)sqlite3Malloc(pVfs->szOsFile * 2);
+ pJournal = (sqlite3_file *)(((u8 *)pMaster) + pVfs->szOsFile);
+ if( !pMaster ){
+ rc = SQLITE_NOMEM;
+ }else{
+ int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MASTER_JOURNAL);
+ rc = sqlite3OsOpen(pVfs, zMaster, pMaster, flags, 0);
+ }
+ if( rc!=SQLITE_OK ) goto delmaster_out;
+ master_open = 1;
+
+ rc = sqlite3OsFileSize(pMaster, &nMasterJournal);
+ if( rc!=SQLITE_OK ) goto delmaster_out;
+
+ if( nMasterJournal>0 ){
+ char *zJournal;
+ char *zMasterPtr = 0;
+ int nMasterPtr = pPager->pVfs->mxPathname+1;
+
+ /* Load the entire master journal file into space obtained from
+ ** sqlite3_malloc() and pointed to by zMasterJournal.
+ */
+ zMasterJournal = (char *)sqlite3Malloc(nMasterJournal + nMasterPtr);
+ if( !zMasterJournal ){
+ rc = SQLITE_NOMEM;
+ goto delmaster_out;
+ }
+ zMasterPtr = &zMasterJournal[nMasterJournal];
+ rc = sqlite3OsRead(pMaster, zMasterJournal, nMasterJournal, 0);
+ if( rc!=SQLITE_OK ) goto delmaster_out;
+
+ zJournal = zMasterJournal;
+ while( (zJournal-zMasterJournal)<nMasterJournal ){
+ int exists;
+ rc = sqlite3OsAccess(pVfs, zJournal, SQLITE_ACCESS_EXISTS, &exists);
+ if( rc!=SQLITE_OK ){
+ goto delmaster_out;
+ }
+ if( exists ){
+ /* One of the journals pointed to by the master journal exists.
+ ** Open it and check if it points at the master journal. If
+ ** so, return without deleting the master journal file.
+ */
+ int c;
+ int flags = (SQLITE_OPEN_READONLY|SQLITE_OPEN_MAIN_JOURNAL);
+ rc = sqlite3OsOpen(pVfs, zJournal, pJournal, flags, 0);
+ if( rc!=SQLITE_OK ){
+ goto delmaster_out;
+ }
+
+ rc = readMasterJournal(pJournal, zMasterPtr, nMasterPtr);
+ sqlite3OsClose(pJournal);
+ if( rc!=SQLITE_OK ){
+ goto delmaster_out;
+ }
+
+ c = zMasterPtr[0]!=0 && strcmp(zMasterPtr, zMaster)==0;
+ if( c ){
+ /* We have a match. Do not delete the master journal file. */
+ goto delmaster_out;
+ }
+ }
+ zJournal += (strlen(zJournal)+1);
+ }
+ }
+
+ rc = sqlite3OsDelete(pVfs, zMaster, 0);
+
+delmaster_out:
+ if( zMasterJournal ){
+ sqlite3_free(zMasterJournal);
+ }
+ if( master_open ){
+ sqlite3OsClose(pMaster);
+ }
+ sqlite3_free(pMaster);
+ return rc;
+}
+
+
+static void pager_truncate_cache(Pager *pPager);
+
+/*
+** Truncate the main file of the given pager to the number of pages
+** indicated. Also truncate the cached representation of the file.
+**
+** Might might be the case that the file on disk is smaller than nPage.
+** This can happen, for example, if we are in the middle of a transaction
+** which has extended the file size and the new pages are still all held
+** in cache, then an INSERT or UPDATE does a statement rollback. Some
+** operating system implementations can get confused if you try to
+** truncate a file to some size that is larger than it currently is,
+** so detect this case and write a single zero byte to the end of the new
+** file instead.
+*/
+static int pager_truncate(Pager *pPager, int nPage){
+ int rc = SQLITE_OK;
+ if( pPager->state>=PAGER_EXCLUSIVE && pPager->fd->pMethods ){
+ i64 currentSize, newSize;
+ rc = sqlite3OsFileSize(pPager->fd, ¤tSize);
+ newSize = pPager->pageSize*(i64)nPage;
+ if( rc==SQLITE_OK && currentSize!=newSize ){
+ if( currentSize>newSize ){
+ rc = sqlite3OsTruncate(pPager->fd, newSize);
+ }else{
+ rc = sqlite3OsWrite(pPager->fd, "", 1, newSize-1);
+ }
+ }
+ }
+ if( rc==SQLITE_OK ){
+ pPager->dbSize = nPage;
+ pager_truncate_cache(pPager);
+ }
+ return rc;
+}
+
+/*
+** Set the sectorSize for the given pager.
+**
+** The sector size is at least as big as the sector size reported
+** by sqlite3OsSectorSize(). The minimum sector size is 512.
+*/
+static void setSectorSize(Pager *pPager){
+ assert(pPager->fd->pMethods||pPager->tempFile);
+ if( !pPager->tempFile ){
+ /* Sector size doesn't matter for temporary files. Also, the file
+ ** may not have been opened yet, in whcih case the OsSectorSize()
+ ** call will segfault.
+ */
+ pPager->sectorSize = sqlite3OsSectorSize(pPager->fd);
+ }
+ if( pPager->sectorSize<512 ){
+ pPager->sectorSize = 512;
+ }
+}
+
+/*
+** Playback the journal and thus restore the database file to
+** the state it was in before we started making changes.
+**
+** The journal file format is as follows:
+**
+** (1) 8 byte prefix. A copy of aJournalMagic[].
+** (2) 4 byte big-endian integer which is the number of valid page records
+** in the journal. If this value is 0xffffffff, then compute the
+** number of page records from the journal size.
+** (3) 4 byte big-endian integer which is the initial value for the
+** sanity checksum.
+** (4) 4 byte integer which is the number of pages to truncate the
+** database to during a rollback.
+** (5) 4 byte big-endian integer which is the sector size. The header
+** is this many bytes in size.
+** (6) 4 byte big-endian integer which is the page case.
+** (7) 4 byte integer which is the number of bytes in the master journal
+** name. The value may be zero (indicate that there is no master
+** journal.)
+** (8) N bytes of the master journal name. The name will be nul-terminated
+** and might be shorter than the value read from (5). If the first byte
+** of the name is \000 then there is no master journal. The master
+** journal name is stored in UTF-8.
+** (9) Zero or more pages instances, each as follows:
+** + 4 byte page number.
+** + pPager->pageSize bytes of data.
+** + 4 byte checksum
+**
+** When we speak of the journal header, we mean the first 8 items above.
+** Each entry in the journal is an instance of the 9th item.
+**
+** Call the value from the second bullet "nRec". nRec is the number of
+** valid page entries in the journal. In most cases, you can compute the
+** value of nRec from the size of the journal file. But if a power
+** failure occurred while the journal was being written, it could be the
+** case that the size of the journal file had already been increased but
+** the extra entries had not yet made it safely to disk. In such a case,
+** the value of nRec computed from the file size would be too large. For
+** that reason, we always use the nRec value in the header.
+**
+** If the nRec value is 0xffffffff it means that nRec should be computed
+** from the file size. This value is used when the user selects the
+** no-sync option for the journal. A power failure could lead to corruption
+** in this case. But for things like temporary table (which will be
+** deleted when the power is restored) we don't care.
+**
+** If the file opened as the journal file is not a well-formed
+** journal file then all pages up to the first corrupted page are rolled
+** back (or no pages if the journal header is corrupted). The journal file
+** is then deleted and SQLITE_OK returned, just as if no corruption had
+** been encountered.
+**
+** If an I/O or malloc() error occurs, the journal-file is not deleted
+** and an error code is returned.
+*/
+static int pager_playback(Pager *pPager, int isHot){
+ sqlite3_vfs *pVfs = pPager->pVfs;
+ i64 szJ; /* Size of the journal file in bytes */
+ u32 nRec; /* Number of Records in the journal */
+ u32 u; /* Unsigned loop counter */
+ Pgno mxPg = 0; /* Size of the original file in pages */
+ int rc; /* Result code of a subroutine */
+ int res = 1; /* Value returned by sqlite3OsAccess() */
+ char *zMaster = 0; /* Name of master journal file if any */
+
+ /* Figure out how many records are in the journal. Abort early if
+ ** the journal is empty.
+ */
+ assert( pPager->journalOpen );
+ rc = sqlite3OsFileSize(pPager->jfd, &szJ);
+ if( rc!=SQLITE_OK || szJ==0 ){
+ goto end_playback;
+ }
+
+ /* Read the master journal name from the journal, if it is present.
+ ** If a master journal file name is specified, but the file is not
+ ** present on disk, then the journal is not hot and does not need to be
+ ** played back.
+ */
+ zMaster = pPager->pTmpSpace;
+ rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
+ if( rc==SQLITE_OK && zMaster[0] ){
+ rc = sqlite3OsAccess(pVfs, zMaster, SQLITE_ACCESS_EXISTS, &res);
+ }
+ zMaster = 0;
+ if( rc!=SQLITE_OK || !res ){
+ goto end_playback;
+ }
+ pPager->journalOff = 0;
+
+ /* This loop terminates either when the readJournalHdr() call returns
+ ** SQLITE_DONE or an IO error occurs. */
+ while( 1 ){
+
+ /* Read the next journal header from the journal file. If there are
+ ** not enough bytes left in the journal file for a complete header, or
+ ** it is corrupted, then a process must of failed while writing it.
+ ** This indicates nothing more needs to be rolled back.
+ */
+ rc = readJournalHdr(pPager, szJ, &nRec, &mxPg);
+ if( rc!=SQLITE_OK ){
+ if( rc==SQLITE_DONE ){
+ rc = SQLITE_OK;
+ }
+ goto end_playback;
+ }
+
+ /* If nRec is 0xffffffff, then this journal was created by a process
+ ** working in no-sync mode. This means that the rest of the journal
+ ** file consists of pages, there are no more journal headers. Compute
+ ** the value of nRec based on this assumption.
+ */
+ if( nRec==0xffffffff ){
+ assert( pPager->journalOff==JOURNAL_HDR_SZ(pPager) );
+ nRec = (szJ - JOURNAL_HDR_SZ(pPager))/JOURNAL_PG_SZ(pPager);
+ }
+
+ /* If nRec is 0 and this rollback is of a transaction created by this
+ ** process and if this is the final header in the journal, then it means
+ ** that this part of the journal was being filled but has not yet been
+ ** synced to disk. Compute the number of pages based on the remaining
+ ** size of the file.
+ **
+ ** The third term of the test was added to fix ticket #2565.
+ */
+ if( nRec==0 && !isHot &&
+ pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff ){
+ nRec = (szJ - pPager->journalOff) / JOURNAL_PG_SZ(pPager);
+ }
+
+ /* If this is the first header read from the journal, truncate the
+ ** database file back to its original size.
+ */
+ if( pPager->journalOff==JOURNAL_HDR_SZ(pPager) ){
+ rc = pager_truncate(pPager, mxPg);
+ if( rc!=SQLITE_OK ){
+ goto end_playback;
+ }
+ }
+
+ /* Copy original pages out of the journal and back into the database file.
+ */
+ for(u=0; u<nRec; u++){
+ rc = pager_playback_one_page(pPager, pPager->jfd, pPager->journalOff, 1);
+ if( rc!=SQLITE_OK ){
+ if( rc==SQLITE_DONE ){
+ rc = SQLITE_OK;
+ pPager->journalOff = szJ;
+ break;
+ }else{
+ goto end_playback;
+ }
+ }
+ }
+ }
+ /*NOTREACHED*/
+ assert( 0 );
+
+end_playback:
+ if( rc==SQLITE_OK ){
+ zMaster = pPager->pTmpSpace;
+ rc = readMasterJournal(pPager->jfd, zMaster, pPager->pVfs->mxPathname+1);
+ }
+ if( rc==SQLITE_OK ){
+ rc = pager_end_transaction(pPager, zMaster[0]!='\0');
+ }
+ if( rc==SQLITE_OK && zMaster[0] ){
+ /* If there was a master journal and this routine will return success,
+ ** see if it is possible to delete the master journal.
+ */
+ rc = pager_delmaster(pPager, zMaster);
+ }
+
+ /* The Pager.sectorSize variable may have been updated while rolling
+ ** back a journal created by a process with a different sector size
+ ** value. Reset it to the correct value for this process.
+ */
+ setSectorSize(pPager);
+ return rc;
+}
+
+/*
+** Playback the statement journal.
+**
+** This is similar to playing back the transaction journal but with
+** a few extra twists.
+**
+** (1) The number of pages in the database file at the start of
+** the statement is stored in pPager->stmtSize, not in the
+** journal file itself.
+**
+** (2) In addition to playing back the statement journal, also
+** playback all pages of the transaction journal beginning
+** at offset pPager->stmtJSize.
+*/
+static int pager_stmt_playback(Pager *pPager){
+ i64 szJ; /* Size of the full journal */
+ i64 hdrOff;
+ int nRec; /* Number of Records */
+ int i; /* Loop counter */
+ int rc;
+
+ szJ = pPager->journalOff;
+
+ /* Set hdrOff to be the offset just after the end of the last journal
+ ** page written before the first journal-header for this statement
+ ** transaction was written, or the end of the file if no journal
+ ** header was written.
+ */
+ hdrOff = pPager->stmtHdrOff;
+ assert( pPager->fullSync || !hdrOff );
+ if( !hdrOff ){
+ hdrOff = szJ;
+ }
+
+ /* Truncate the database back to its original size.
+ */
+ rc = pager_truncate(pPager, pPager->stmtSize);
+ assert( pPager->state>=PAGER_SHARED );
+
+ /* Figure out how many records are in the statement journal.
+ */
+ assert( pPager->stmtInUse && pPager->journalOpen );
+ nRec = pPager->stmtNRec;
+
+ /* Copy original pages out of the statement journal and back into the
+ ** database file. Note that the statement journal omits checksums from
+ ** each record since power-failure recovery is not important to statement
+ ** journals.
+ */
+ for(i=0; i<nRec; i++){
+ i64 offset = i*(4+pPager->pageSize);
+ rc = pager_playback_one_page(pPager, pPager->stfd, offset, 0);
+ assert( rc!=SQLITE_DONE );
+ if( rc!=SQLITE_OK ) goto end_stmt_playback;
+ }
+
+ /* Now roll some pages back from the transaction journal. Pager.stmtJSize
+ ** was the size of the journal file when this statement was started, so
+ ** everything after that needs to be rolled back, either into the
+ ** database, the memory cache, or both.
+ **
+ ** If it is not zero, then Pager.stmtHdrOff is the offset to the start
+ ** of the first journal header written during this statement transaction.
+ */
+ pPager->journalOff = pPager->stmtJSize;
+ pPager->cksumInit = pPager->stmtCksum;
+ while( pPager->journalOff < hdrOff ){
+ rc = pager_playback_one_page(pPager, pPager->jfd, pPager->journalOff, 1);
+ assert( rc!=SQLITE_DONE );
+ if( rc!=SQLITE_OK ) goto end_stmt_playback;
+ }
+
+ while( pPager->journalOff < szJ ){
+ u32 nJRec; /* Number of Journal Records */
+ u32 dummy;
+ rc = readJournalHdr(pPager, szJ, &nJRec, &dummy);
+ if( rc!=SQLITE_OK ){
+ assert( rc!=SQLITE_DONE );
+ goto end_stmt_playback;
+ }
+ if( nJRec==0 ){
+ nJRec = (szJ - pPager->journalOff) / (pPager->pageSize+8);
+ }
+ for(i=nJRec-1; i>=0 && pPager->journalOff < szJ; i--){
+ rc = pager_playback_one_page(pPager, pPager->jfd, pPager->journalOff, 1);
+ assert( rc!=SQLITE_DONE );
+ if( rc!=SQLITE_OK ) goto end_stmt_playback;
+ }
+ }
+
+ pPager->journalOff = szJ;
+
+end_stmt_playback:
+ if( rc==SQLITE_OK) {
+ pPager->journalOff = szJ;
+ /* pager_reload_cache(pPager); */
+ }
+ return rc;
+}
+
+/*
+** Change the maximum number of in-memory pages that are allowed.
+*/
+void sqlite3PagerSetCachesize(Pager *pPager, int mxPage){
+ if( mxPage>10 ){
+ pPager->mxPage = mxPage;
+ }else{
+ pPager->mxPage = 10;
+ }
+}
+
+/*
+** Adjust the robustness of the database to damage due to OS crashes
+** or power failures by changing the number of syncs()s when writing
+** the rollback journal. There are three levels:
+**
+** OFF sqlite3OsSync() is never called. This is the default
+** for temporary and transient files.
+**
+** NORMAL The journal is synced once before writes begin on the
+** database. This is normally adequate protection, but
+** it is theoretically possible, though very unlikely,
+** that an inopertune power failure could leave the journal
+** in a state which would cause damage to the database
+** when it is rolled back.
+**
+** FULL The journal is synced twice before writes begin on the
+** database (with some additional information - the nRec field
+** of the journal header - being written in between the two
+** syncs). If we assume that writing a
+** single disk sector is atomic, then this mode provides
+** assurance that the journal will not be corrupted to the
+** point of causing damage to the database during rollback.
+**
+** Numeric values associated with these states are OFF==1, NORMAL=2,
+** and FULL=3.
+*/
+#ifndef SQLITE_OMIT_PAGER_PRAGMAS
+void sqlite3PagerSetSafetyLevel(Pager *pPager, int level, int full_fsync){
+ pPager->noSync = level==1 || pPager->tempFile;
+ pPager->fullSync = level==3 && !pPager->tempFile;
+ pPager->sync_flags = (full_fsync?SQLITE_SYNC_FULL:SQLITE_SYNC_NORMAL);
+ if( pPager->noSync ) pPager->needSync = 0;
+}
+#endif
+
+/*
+** The following global variable is incremented whenever the library
+** attempts to open a temporary file. This information is used for
+** testing and analysis only.
+*/
+#ifdef SQLITE_TEST
+int sqlite3_opentemp_count = 0;
+#endif
+
+/*
+** Open a temporary file.
+**
+** Write the file descriptor into *fd. Return SQLITE_OK on success or some
+** other error code if we fail. The OS will automatically delete the temporary
+** file when it is closed.
+*/
+static int sqlite3PagerOpentemp(
+ Pager *pPager, /* The pager object */
+ sqlite3_file *pFile, /* Write the file descriptor here */
+ int vfsFlags /* Flags passed through to the VFS */
+){
+ int rc;
+
+#ifdef SQLITE_TEST
+ sqlite3_opentemp_count++; /* Used for testing and analysis only */
+#endif
+
+ vfsFlags |= SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE |
+ SQLITE_OPEN_EXCLUSIVE | SQLITE_OPEN_DELETEONCLOSE;
+ rc = sqlite3OsOpen(pPager->pVfs, 0, pFile, vfsFlags, 0);
+ assert( rc!=SQLITE_OK || pFile->pMethods );
+ return rc;
+}
+
+/*
+** Create a new page cache and put a pointer to the page cache in *ppPager.
+** The file to be cached need not exist. The file is not locked until
+** the first call to sqlite3PagerGet() and is only held open until the
+** last page is released using sqlite3PagerUnref().
+**
+** If zFilename is NULL then a randomly-named temporary file is created
+** and used as the file to be cached. The file will be deleted
+** automatically when it is closed.
+**
+** If zFilename is ":memory:" then all information is held in cache.
+** It is never written to disk. This can be used to implement an
+** in-memory database.
+*/
+int sqlite3PagerOpen(
+ sqlite3_vfs *pVfs, /* The virtual file system to use */
+ Pager **ppPager, /* Return the Pager structure here */
+ const char *zFilename, /* Name of the database file to open */
+ int nExtra, /* Extra bytes append to each in-memory page */
+ int flags, /* flags controlling this file */
+ int vfsFlags /* flags passed through to sqlite3_vfs.xOpen() */
+){
+ u8 *pPtr;
+ Pager *pPager = 0;
+ int rc = SQLITE_OK;
+ int i;
+ int tempFile = 0;
+ int memDb = 0;
+ int readOnly = 0;
+ int useJournal = (flags & PAGER_OMIT_JOURNAL)==0;
+ int noReadlock = (flags & PAGER_NO_READLOCK)!=0;
+ int journalFileSize = sqlite3JournalSize(pVfs);
+ int szPageDflt = SQLITE_DEFAULT_PAGE_SIZE;
+ char *zPathname = 0;
+ int nPathname = 0;
+
+ /* The default return is a NULL pointer */
+ *ppPager = 0;
+
+ /* Compute and store the full pathname in an allocated buffer pointed
+ ** to by zPathname, length nPathname. Or, if this is a temporary file,
+ ** leave both nPathname and zPathname set to 0.
+ */
+ if( zFilename && zFilename[0] ){
+ nPathname = pVfs->mxPathname+1;
+ zPathname = sqlite3Malloc(nPathname*2);
+ if( zPathname==0 ){
+ return SQLITE_NOMEM;
+ }
+#ifndef SQLITE_OMIT_MEMORYDB
+ if( strcmp(zFilename,":memory:")==0 ){
+ memDb = 1;
+ zPathname[0] = 0;
+ }else
+#endif
+ {
+ rc = sqlite3OsFullPathname(pVfs, zFilename, nPathname, zPathname);
+ }
+ if( rc!=SQLITE_OK ){
+ sqlite3_free(zPathname);
+ return rc;
+ }
+ nPathname = strlen(zPathname);
+ }
+
+ /* Allocate memory for the pager structure */
+ pPager = sqlite3MallocZero(
+ sizeof(*pPager) + /* Pager structure */
+ journalFileSize + /* The journal file structure */
+ pVfs->szOsFile * 3 + /* The main db and two journal files */
+ 3*nPathname + 40 /* zFilename, zDirectory, zJournal */
+ );
+ if( !pPager ){
+ sqlite3_free(zPathname);
+ return SQLITE_NOMEM;
+ }
+ pPtr = (u8 *)&pPager[1];
+ pPager->vfsFlags = vfsFlags;
+ pPager->fd = (sqlite3_file*)&pPtr[pVfs->szOsFile*0];
+ pPager->stfd = (sqlite3_file*)&pPtr[pVfs->szOsFile*1];
+ pPager->jfd = (sqlite3_file*)&pPtr[pVfs->szOsFile*2];
+ pPager->zFilename = (char*)&pPtr[pVfs->szOsFile*2+journalFileSize];
+ pPager->zDirectory = &pPager->zFilename[nPathname+1];
+ pPager->zJournal = &pPager->zDirectory[nPathname+1];
+ pPager->pVfs = pVfs;
+ if( zPathname ){
+ memcpy(pPager->zFilename, zPathname, nPathname+1);
+ sqlite3_free(zPathname);
+ }
+
+ /* Open the pager file.
+ */
+ if( zFilename && zFilename[0] && !memDb ){
+ if( nPathname>(pVfs->mxPathname - sizeof("-journal")) ){
+ rc = SQLITE_CANTOPEN;
+ }else{
+ int fout = 0;
+ rc = sqlite3OsOpen(pVfs, pPager->zFilename, pPager->fd,
+ pPager->vfsFlags, &fout);
+ readOnly = (fout&SQLITE_OPEN_READONLY);
+
+ /* If the file was successfully opened for read/write access,
+ ** choose a default page size in case we have to create the
+ ** database file. The default page size is the maximum of:
+ **
+ ** + SQLITE_DEFAULT_PAGE_SIZE,
+ ** + The value returned by sqlite3OsSectorSize()
+ ** + The largest page size that can be written atomically.
+ */
+ if( rc==SQLITE_OK && !readOnly ){
+ int iSectorSize = sqlite3OsSectorSize(pPager->fd);
+ if( szPageDflt<iSectorSize ){
+ szPageDflt = iSectorSize;
+ }
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+ {
+ int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
+ int ii;
+ assert(SQLITE_IOCAP_ATOMIC512==(512>>8));
+ assert(SQLITE_IOCAP_ATOMIC64K==(65536>>8));
+ assert(SQLITE_MAX_DEFAULT_PAGE_SIZE<=65536);
+ for(ii=szPageDflt; ii<=SQLITE_MAX_DEFAULT_PAGE_SIZE; ii=ii*2){
+ if( iDc&(SQLITE_IOCAP_ATOMIC|(ii>>8)) ) szPageDflt = ii;
+ }
+ }
+#endif
+ if( szPageDflt>SQLITE_MAX_DEFAULT_PAGE_SIZE ){
+ szPageDflt = SQLITE_MAX_DEFAULT_PAGE_SIZE;
+ }
+ }
+ }
+ }else if( !memDb ){
+ /* If a temporary file is requested, it is not opened immediately.
+ ** In this case we accept the default page size and delay actually
+ ** opening the file until the first call to OsWrite().
+ */
+ tempFile = 1;
+ pPager->state = PAGER_EXCLUSIVE;
+ }
+
+ if( pPager && rc==SQLITE_OK ){
+ pPager->pTmpSpace = sqlite3PageMalloc(szPageDflt);
+ }
+
+ /* If an error occured in either of the blocks above.
+ ** Free the Pager structure and close the file.
+ ** Since the pager is not allocated there is no need to set
+ ** any Pager.errMask variables.
+ */
+ if( !pPager || !pPager->pTmpSpace ){
+ sqlite3OsClose(pPager->fd);
+ sqlite3_free(pPager);
+ return ((rc==SQLITE_OK)?SQLITE_NOMEM:rc);
+ }
+
+ PAGERTRACE3("OPEN %d %s\n", FILEHANDLEID(pPager->fd), pPager->zFilename);
+ IOTRACE(("OPEN %p %s\n", pPager, pPager->zFilename))
+
+ /* Fill in Pager.zDirectory[] */
+ memcpy(pPager->zDirectory, pPager->zFilename, nPathname+1);
+ for(i=strlen(pPager->zDirectory); i>0 && pPager->zDirectory[i-1]!='/'; i--){}
+ if( i>0 ) pPager->zDirectory[i-1] = 0;
+
+ /* Fill in Pager.zJournal[] */
+ if( zPathname ){
+ memcpy(pPager->zJournal, pPager->zFilename, nPathname);
+ memcpy(&pPager->zJournal[nPathname], "-journal", 9);
+ }else{
+ pPager->zJournal = 0;
+ }
+
+ /* pPager->journalOpen = 0; */
+ pPager->useJournal = useJournal && !memDb;
+ pPager->noReadlock = noReadlock && readOnly;
+ /* pPager->stmtOpen = 0; */
+ /* pPager->stmtInUse = 0; */
+ /* pPager->nRef = 0; */
+ pPager->dbSize = memDb-1;
+ pPager->pageSize = szPageDflt;
+ /* pPager->stmtSize = 0; */
+ /* pPager->stmtJSize = 0; */
+ /* pPager->nPage = 0; */
+ pPager->mxPage = 100;
+ pPager->mxPgno = SQLITE_MAX_PAGE_COUNT;
+ /* pPager->state = PAGER_UNLOCK; */
+ assert( pPager->state == (tempFile ? PAGER_EXCLUSIVE : PAGER_UNLOCK) );
+ /* pPager->errMask = 0; */
+ pPager->tempFile = tempFile;
+ assert( tempFile==PAGER_LOCKINGMODE_NORMAL
+ || tempFile==PAGER_LOCKINGMODE_EXCLUSIVE );
+ assert( PAGER_LOCKINGMODE_EXCLUSIVE==1 );
+ pPager->exclusiveMode = tempFile;
+ pPager->memDb = memDb;
+ pPager->readOnly = readOnly;
+ /* pPager->needSync = 0; */
+ pPager->noSync = pPager->tempFile || !useJournal;
+ pPager->fullSync = (pPager->noSync?0:1);
+ pPager->sync_flags = SQLITE_SYNC_NORMAL;
+ /* pPager->pFirst = 0; */
+ /* pPager->pFirstSynced = 0; */
+ /* pPager->pLast = 0; */
+ pPager->nExtra = FORCE_ALIGNMENT(nExtra);
+ pPager->journalSizeLimit = SQLITE_DEFAULT_JOURNAL_SIZE_LIMIT;
+ assert(pPager->fd->pMethods||memDb||tempFile);
+ if( !memDb ){
+ setSectorSize(pPager);
+ }
+ /* pPager->pBusyHandler = 0; */
+ /* memset(pPager->aHash, 0, sizeof(pPager->aHash)); */
+ *ppPager = pPager;
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ pPager->iInUseMM = 0;
+ pPager->iInUseDB = 0;
+ if( !memDb ){
+#ifndef SQLITE_MUTEX_NOOP
+ sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM2);
+#endif
+ sqlite3_mutex_enter(mutex);
+ pPager->pNext = sqlite3PagerList;
+ if( sqlite3PagerList ){
+ assert( sqlite3PagerList->pPrev==0 );
+ sqlite3PagerList->pPrev = pPager;
+ }
+ pPager->pPrev = 0;
+ sqlite3PagerList = pPager;
+ sqlite3_mutex_leave(mutex);
+ }
+#endif
+ return SQLITE_OK;
+}
+
+/*
+** Set the busy handler function.
+*/
+void sqlite3PagerSetBusyhandler(Pager *pPager, BusyHandler *pBusyHandler){
+ pPager->pBusyHandler = pBusyHandler;
+}
+
+/*
+** Set the destructor for this pager. If not NULL, the destructor is called
+** when the reference count on each page reaches zero. The destructor can
+** be used to clean up information in the extra segment appended to each page.
+**
+** The destructor is not called as a result sqlite3PagerClose().
+** Destructors are only called by sqlite3PagerUnref().
+*/
+void sqlite3PagerSetDestructor(Pager *pPager, void (*xDesc)(DbPage*,int)){
+ pPager->xDestructor = xDesc;
+}
+
+/*
+** Set the reinitializer for this pager. If not NULL, the reinitializer
+** is called when the content of a page in cache is restored to its original
+** value as a result of a rollback. The callback gives higher-level code
+** an opportunity to restore the EXTRA section to agree with the restored
+** page data.
+*/
+void sqlite3PagerSetReiniter(Pager *pPager, void (*xReinit)(DbPage*,int)){
+ pPager->xReiniter = xReinit;
+}
+
+/*
+** Set the page size to *pPageSize. If the suggest new page size is
+** inappropriate, then an alternative page size is set to that
+** value before returning.
+*/
+int sqlite3PagerSetPagesize(Pager *pPager, u16 *pPageSize){
+ int rc = SQLITE_OK;
+ u16 pageSize = *pPageSize;
+ assert( pageSize==0 || (pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE) );
+ if( pageSize && pageSize!=pPager->pageSize
+ && !pPager->memDb && pPager->nRef==0
+ ){
+ char *pNew = (char *)sqlite3PageMalloc(pageSize);
+ if( !pNew ){
+ rc = SQLITE_NOMEM;
+ }else{
+ pagerEnter(pPager);
+ pager_reset(pPager);
+ pPager->pageSize = pageSize;
+ setSectorSize(pPager);
+ sqlite3PageFree(pPager->pTmpSpace);
+ pPager->pTmpSpace = pNew;
+ pagerLeave(pPager);
+ }
+ }
+ *pPageSize = pPager->pageSize;
+ return rc;
+}
+
+/*
+** Return a pointer to the "temporary page" buffer held internally
+** by the pager. This is a buffer that is big enough to hold the
+** entire content of a database page. This buffer is used internally
+** during rollback and will be overwritten whenever a rollback
+** occurs. But other modules are free to use it too, as long as
+** no rollbacks are happening.
+*/
+void *sqlite3PagerTempSpace(Pager *pPager){
+ return pPager->pTmpSpace;
+}
+
+/*
+** Attempt to set the maximum database page count if mxPage is positive.
+** Make no changes if mxPage is zero or negative. And never reduce the
+** maximum page count below the current size of the database.
+**
+** Regardless of mxPage, return the current maximum page count.
+*/
+int sqlite3PagerMaxPageCount(Pager *pPager, int mxPage){
+ if( mxPage>0 ){
+ pPager->mxPgno = mxPage;
+ }
+ sqlite3PagerPagecount(pPager, 0);
+ return pPager->mxPgno;
+}
+
+/*
+** The following set of routines are used to disable the simulated
+** I/O error mechanism. These routines are used to avoid simulated
+** errors in places where we do not care about errors.
+**
+** Unless -DSQLITE_TEST=1 is used, these routines are all no-ops
+** and generate no code.
+*/
+#ifdef SQLITE_TEST
+extern int sqlite3_io_error_pending;
+extern int sqlite3_io_error_hit;
+static int saved_cnt;
+void disable_simulated_io_errors(void){
+ saved_cnt = sqlite3_io_error_pending;
+ sqlite3_io_error_pending = -1;
+}
+void enable_simulated_io_errors(void){
+ sqlite3_io_error_pending = saved_cnt;
+}
+#else
+# define disable_simulated_io_errors()
+# define enable_simulated_io_errors()
+#endif
+
+/*
+** Read the first N bytes from the beginning of the file into memory
+** that pDest points to.
+**
+** No error checking is done. The rational for this is that this function
+** may be called even if the file does not exist or contain a header. In
+** these cases sqlite3OsRead() will return an error, to which the correct
+** response is to zero the memory at pDest and continue. A real IO error
+** will presumably recur and be picked up later (Todo: Think about this).
+*/
+int sqlite3PagerReadFileheader(Pager *pPager, int N, unsigned char *pDest){
+ int rc = SQLITE_OK;
+ memset(pDest, 0, N);
+ assert(MEMDB||pPager->fd->pMethods||pPager->tempFile);
+ if( pPager->fd->pMethods ){
+ IOTRACE(("DBHDR %p 0 %d\n", pPager, N))
+ rc = sqlite3OsRead(pPager->fd, pDest, N, 0);
+ if( rc==SQLITE_IOERR_SHORT_READ ){
+ rc = SQLITE_OK;
+ }
+ }
+ return rc;
+}
+
+/*
+** Return the total number of pages in the disk file associated with
+** pPager.
+**
+** If the PENDING_BYTE lies on the page directly after the end of the
+** file, then consider this page part of the file too. For example, if
+** PENDING_BYTE is byte 4096 (the first byte of page 5) and the size of the
+** file is 4096 bytes, 5 is returned instead of 4.
+*/
+int sqlite3PagerPagecount(Pager *pPager, int *pnPage){
+ i64 n = 0;
+ int rc;
+ assert( pPager!=0 );
+ if( pPager->errCode ){
+ return pPager->errCode;
+ }
+ if( pPager->dbSize>=0 ){
+ n = pPager->dbSize;
+ } else {
+ assert(pPager->fd->pMethods||pPager->tempFile);
+ if( (pPager->fd->pMethods)
+ && (rc = sqlite3OsFileSize(pPager->fd, &n))!=SQLITE_OK ){
+ pPager->nRef++;
+ pager_error(pPager, rc);
+ pPager->nRef--;
+ return rc;
+ }
+ if( n>0 && n<pPager->pageSize ){
+ n = 1;
+ }else{
+ n /= pPager->pageSize;
+ }
+ if( pPager->state!=PAGER_UNLOCK ){
+ pPager->dbSize = n;
+ }
+ }
+ if( n==(PENDING_BYTE/pPager->pageSize) ){
+ n++;
+ }
+ if( n>pPager->mxPgno ){
+ pPager->mxPgno = n;
+ }
+ if( pnPage ){
+ *pnPage = n;
+ }
+ return SQLITE_OK;
+}
+
+
+#ifndef SQLITE_OMIT_MEMORYDB
+/*
+** Clear a PgHistory block
+*/
+static void clearHistory(PgHistory *pHist){
+ sqlite3PageFree(pHist->pOrig);
+ sqlite3PageFree(pHist->pStmt);
+ pHist->pOrig = 0;
+ pHist->pStmt = 0;
+}
+#else
+#define clearHistory(x)
+#endif
+
+/*
+** Forward declaration
+*/
+static int syncJournal(Pager*);
+
+/*
+** Unlink pPg from its hash chain. Also set the page number to 0 to indicate
+** that the page is not part of any hash chain. This is required because the
+** sqlite3PagerMovepage() routine can leave a page in the
+** pNextFree/pPrevFree list that is not a part of any hash-chain.
+*/
+static void unlinkHashChain(Pager *pPager, PgHdr *pPg){
+ if( pPg->pgno==0 ){
+ assert( pPg->pNextHash==0 && pPg->pPrevHash==0 );
+ return;
+ }
+ if( pPg->pNextHash ){
+ pPg->pNextHash->pPrevHash = pPg->pPrevHash;
+ }
+ if( pPg->pPrevHash ){
+ assert( pPager->aHash[pPg->pgno & (pPager->nHash-1)]!=pPg );
+ pPg->pPrevHash->pNextHash = pPg->pNextHash;
+ }else{
+ int h = pPg->pgno & (pPager->nHash-1);
+ pPager->aHash[h] = pPg->pNextHash;
+ }
+ if( MEMDB ){
+ clearHistory(PGHDR_TO_HIST(pPg, pPager));
+ }
+ pPg->pgno = 0;
+ pPg->pNextHash = pPg->pPrevHash = 0;
+}
+
+/*
+** Unlink a page from the free list (the list of all pages where nRef==0)
+** and from its hash collision chain.
+*/
+static void unlinkPage(PgHdr *pPg){
+ Pager *pPager = pPg->pPager;
+
+ /* Unlink from free page list */
+ lruListRemove(pPg);
+
+ /* Unlink from the pgno hash table */
+ unlinkHashChain(pPager, pPg);
+}
+
+/*
+** This routine is used to truncate the cache when a database
+** is truncated. Drop from the cache all pages whose pgno is
+** larger than pPager->dbSize and is unreferenced.
+**
+** Referenced pages larger than pPager->dbSize are zeroed.
+**
+** Actually, at the point this routine is called, it would be
+** an error to have a referenced page. But rather than delete
+** that page and guarantee a subsequent segfault, it seems better
+** to zero it and hope that we error out sanely.
+*/
+static void pager_truncate_cache(Pager *pPager){
+ PgHdr *pPg;
+ PgHdr **ppPg;
+ int dbSize = pPager->dbSize;
+
+ ppPg = &pPager->pAll;
+ while( (pPg = *ppPg)!=0 ){
+ if( pPg->pgno<=dbSize ){
+ ppPg = &pPg->pNextAll;
+ }else if( pPg->nRef>0 ){
+ memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
+ ppPg = &pPg->pNextAll;
+ }else{
+ *ppPg = pPg->pNextAll;
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ if( *ppPg ){
+ (*ppPg)->pPrevAll = pPg->pPrevAll;
+ }
+#endif
+ IOTRACE(("PGFREE %p %d\n", pPager, pPg->pgno));
+ PAGER_INCR(sqlite3_pager_pgfree_count);
+ unlinkPage(pPg);
+ makeClean(pPg);
+ sqlite3PageFree(pPg->pData);
+ sqlite3_free(pPg);
+ pPager->nPage--;
+ }
+ }
+}
+
+/*
+** Try to obtain a lock on a file. Invoke the busy callback if the lock
+** is currently not available. Repeat until the busy callback returns
+** false or until the lock succeeds.
+**
+** Return SQLITE_OK on success and an error code if we cannot obtain
+** the lock.
+*/
+static int pager_wait_on_lock(Pager *pPager, int locktype){
+ int rc;
+
+ /* The OS lock values must be the same as the Pager lock values */
+ assert( PAGER_SHARED==SHARED_LOCK );
+ assert( PAGER_RESERVED==RESERVED_LOCK );
+ assert( PAGER_EXCLUSIVE==EXCLUSIVE_LOCK );
+
+ /* If the file is currently unlocked then the size must be unknown */
+ assert( pPager->state>=PAGER_SHARED || pPager->dbSize<0 || MEMDB );
+
+ if( pPager->state>=locktype ){
+ rc = SQLITE_OK;
+ }else{
+ if( pPager->pBusyHandler ) pPager->pBusyHandler->nBusy = 0;
+ do {
+ rc = sqlite3OsLock(pPager->fd, locktype);
+ }while( rc==SQLITE_BUSY && sqlite3InvokeBusyHandler(pPager->pBusyHandler) );
+ if( rc==SQLITE_OK ){
+ pPager->state = locktype;
+ IOTRACE(("LOCK %p %d\n", pPager, locktype))
+ }
+ }
+ return rc;
+}
+
+/*
+** Truncate the file to the number of pages specified.
+*/
+int sqlite3PagerTruncate(Pager *pPager, Pgno nPage){
+ int rc;
+ assert( pPager->state>=PAGER_SHARED || MEMDB );
+ sqlite3PagerPagecount(pPager, 0);
+ if( pPager->errCode ){
+ rc = pPager->errCode;
+ return rc;
+ }
+ if( nPage>=(unsigned)pPager->dbSize ){
+ return SQLITE_OK;
+ }
+ if( MEMDB ){
+ pPager->dbSize = nPage;
+ pager_truncate_cache(pPager);
+ return SQLITE_OK;
+ }
+ pagerEnter(pPager);
+ rc = syncJournal(pPager);
+ pagerLeave(pPager);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+
+ /* Get an exclusive lock on the database before truncating. */
+ pagerEnter(pPager);
+ rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
+ pagerLeave(pPager);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+
+ rc = pager_truncate(pPager, nPage);
+ return rc;
+}
+
+/*
+** Shutdown the page cache. Free all memory and close all files.
+**
+** If a transaction was in progress when this routine is called, that
+** transaction is rolled back. All outstanding pages are invalidated
+** and their memory is freed. Any attempt to use a page associated
+** with this page cache after this function returns will likely
+** result in a coredump.
+**
+** This function always succeeds. If a transaction is active an attempt
+** is made to roll it back. If an error occurs during the rollback
+** a hot journal may be left in the filesystem but no error is returned
+** to the caller.
+*/
+int sqlite3PagerClose(Pager *pPager){
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ if( !MEMDB ){
+#ifndef SQLITE_MUTEX_NOOP
+ sqlite3_mutex *mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM2);
+#endif
+ sqlite3_mutex_enter(mutex);
+ if( pPager->pPrev ){
+ pPager->pPrev->pNext = pPager->pNext;
+ }else{
+ sqlite3PagerList = pPager->pNext;
+ }
+ if( pPager->pNext ){
+ pPager->pNext->pPrev = pPager->pPrev;
+ }
+ sqlite3_mutex_leave(mutex);
+ }
+#endif
+
+ disable_simulated_io_errors();
+ sqlite3BeginBenignMalloc();
+ pPager->errCode = 0;
+ pPager->exclusiveMode = 0;
+ pager_reset(pPager);
+ pagerUnlockAndRollback(pPager);
+ enable_simulated_io_errors();
+ sqlite3EndBenignMalloc();
+ PAGERTRACE2("CLOSE %d\n", PAGERID(pPager));
+ IOTRACE(("CLOSE %p\n", pPager))
+ if( pPager->journalOpen ){
+ sqlite3OsClose(pPager->jfd);
+ }
+ sqlite3BitvecDestroy(pPager->pInJournal);
+ if( pPager->stmtOpen ){
+ sqlite3OsClose(pPager->stfd);
+ }
+ sqlite3OsClose(pPager->fd);
+ /* Temp files are automatically deleted by the OS
+ ** if( pPager->tempFile ){
+ ** sqlite3OsDelete(pPager->zFilename);
+ ** }
+ */
+
+ sqlite3_free(pPager->aHash);
+ sqlite3PageFree(pPager->pTmpSpace);
+ sqlite3_free(pPager);
+ return SQLITE_OK;
+}
+
+#if !defined(NDEBUG) || defined(SQLITE_TEST)
+/*
+** Return the page number for the given page data.
+*/
+Pgno sqlite3PagerPagenumber(DbPage *p){
+ return p->pgno;
+}
+#endif
+
+/*
+** The page_ref() function increments the reference count for a page.
+** If the page is currently on the freelist (the reference count is zero) then
+** remove it from the freelist.
+**
+** For non-test systems, page_ref() is a macro that calls _page_ref()
+** online of the reference count is zero. For test systems, page_ref()
+** is a real function so that we can set breakpoints and trace it.
+*/
+static void _page_ref(PgHdr *pPg){
+ if( pPg->nRef==0 ){
+ /* The page is currently on the freelist. Remove it. */
+ lruListRemove(pPg);
+ pPg->pPager->nRef++;
+ }
+ pPg->nRef++;
+}
+#ifdef SQLITE_DEBUG
+ static void page_ref(PgHdr *pPg){
+ if( pPg->nRef==0 ){
+ _page_ref(pPg);
+ }else{
+ pPg->nRef++;
+ }
+ }
+#else
+# define page_ref(P) ((P)->nRef==0?_page_ref(P):(void)(P)->nRef++)
+#endif
+
+/*
+** Increment the reference count for a page. The input pointer is
+** a reference to the page data.
+*/
+int sqlite3PagerRef(DbPage *pPg){
+ pagerEnter(pPg->pPager);
+ page_ref(pPg);
+ pagerLeave(pPg->pPager);
+ return SQLITE_OK;
+}
+
+/*
+** Sync the journal. In other words, make sure all the pages that have
+** been written to the journal have actually reached the surface of the
+** disk. It is not safe to modify the original database file until after
+** the journal has been synced. If the original database is modified before
+** the journal is synced and a power failure occurs, the unsynced journal
+** data would be lost and we would be unable to completely rollback the
+** database changes. Database corruption would occur.
+**
+** This routine also updates the nRec field in the header of the journal.
+** (See comments on the pager_playback() routine for additional information.)
+** If the sync mode is FULL, two syncs will occur. First the whole journal
+** is synced, then the nRec field is updated, then a second sync occurs.
+**
+** For temporary databases, we do not care if we are able to rollback
+** after a power failure, so no sync occurs.
+**
+** If the IOCAP_SEQUENTIAL flag is set for the persistent media on which
+** the database is stored, then OsSync() is never called on the journal
+** file. In this case all that is required is to update the nRec field in
+** the journal header.
+**
+** This routine clears the needSync field of every page current held in
+** memory.
+*/
+static int syncJournal(Pager *pPager){
+ PgHdr *pPg;
+ int rc = SQLITE_OK;
+
+ /* Sync the journal before modifying the main database
+ ** (assuming there is a journal and it needs to be synced.)
+ */
+ if( pPager->needSync ){
+ if( !pPager->tempFile ){
+ int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
+ assert( pPager->journalOpen );
+
+ if( 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
+ /* Write the nRec value into the journal file header. If in
+ ** full-synchronous mode, sync the journal first. This ensures that
+ ** all data has really hit the disk before nRec is updated to mark
+ ** it as a candidate for rollback.
+ **
+ ** This is not required if the persistent media supports the
+ ** SAFE_APPEND property. Because in this case it is not possible
+ ** for garbage data to be appended to the file, the nRec field
+ ** is populated with 0xFFFFFFFF when the journal header is written
+ ** and never needs to be updated.
+ */
+ i64 jrnlOff;
+ if( pPager->fullSync && 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){
+ PAGERTRACE2("SYNC journal of %d\n", PAGERID(pPager));
+ IOTRACE(("JSYNC %p\n", pPager))
+ rc = sqlite3OsSync(pPager->jfd, pPager->sync_flags);
+ if( rc!=0 ) return rc;
+ }
+
+ jrnlOff = pPager->journalHdr + sizeof(aJournalMagic);
+ IOTRACE(("JHDR %p %lld %d\n", pPager, jrnlOff, 4));
+ rc = write32bits(pPager->jfd, jrnlOff, pPager->nRec);
+ if( rc ) return rc;
+ }
+ if( 0==(iDc&SQLITE_IOCAP_SEQUENTIAL) ){
+ PAGERTRACE2("SYNC journal of %d\n", PAGERID(pPager));
+ IOTRACE(("JSYNC %p\n", pPager))
+ rc = sqlite3OsSync(pPager->jfd, pPager->sync_flags|
+ (pPager->sync_flags==SQLITE_SYNC_FULL?SQLITE_SYNC_DATAONLY:0)
+ );
+ if( rc!=0 ) return rc;
+ }
+ pPager->journalStarted = 1;
+ }
+ pPager->needSync = 0;
+
+ /* Erase the needSync flag from every page.
+ */
+ for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
+ pPg->needSync = 0;
+ }
+ lruListSetFirstSynced(pPager);
+ }
+
+#ifndef NDEBUG
+ /* If the Pager.needSync flag is clear then the PgHdr.needSync
+ ** flag must also be clear for all pages. Verify that this
+ ** invariant is true.
+ */
+ else{
+ for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
+ assert( pPg->needSync==0 );
+ }
+ assert( pPager->lru.pFirstSynced==pPager->lru.pFirst );
+ }
+#endif
+
+ return rc;
+}
+
+/*
+** Merge two lists of pages connected by pDirty and in pgno order.
+** Do not both fixing the pPrevDirty pointers.
+*/
+static PgHdr *merge_pagelist(PgHdr *pA, PgHdr *pB){
+ PgHdr result, *pTail;
+ pTail = &result;
+ while( pA && pB ){
+ if( pA->pgno<pB->pgno ){
+ pTail->pDirty = pA;
+ pTail = pA;
+ pA = pA->pDirty;
+ }else{
+ pTail->pDirty = pB;
+ pTail = pB;
+ pB = pB->pDirty;
+ }
+ }
+ if( pA ){
+ pTail->pDirty = pA;
+ }else if( pB ){
+ pTail->pDirty = pB;
+ }else{
+ pTail->pDirty = 0;
+ }
+ return result.pDirty;
+}
+
+/*
+** Sort the list of pages in accending order by pgno. Pages are
+** connected by pDirty pointers. The pPrevDirty pointers are
+** corrupted by this sort.
+*/
+#define N_SORT_BUCKET_ALLOC 25
+#define N_SORT_BUCKET 25
+#ifdef SQLITE_TEST
+ int sqlite3_pager_n_sort_bucket = 0;
+ #undef N_SORT_BUCKET
+ #define N_SORT_BUCKET \
+ (sqlite3_pager_n_sort_bucket?sqlite3_pager_n_sort_bucket:N_SORT_BUCKET_ALLOC)
+#endif
+static PgHdr *sort_pagelist(PgHdr *pIn){
+ PgHdr *a[N_SORT_BUCKET_ALLOC], *p;
+ int i;
+ memset(a, 0, sizeof(a));
+ while( pIn ){
+ p = pIn;
+ pIn = p->pDirty;
+ p->pDirty = 0;
+ for(i=0; i<N_SORT_BUCKET-1; i++){
+ if( a[i]==0 ){
+ a[i] = p;
+ break;
+ }else{
+ p = merge_pagelist(a[i], p);
+ a[i] = 0;
+ }
+ }
+ if( i==N_SORT_BUCKET-1 ){
+ /* Coverage: To get here, there need to be 2^(N_SORT_BUCKET)
+ ** elements in the input list. This is possible, but impractical.
+ ** Testing this line is the point of global variable
+ ** sqlite3_pager_n_sort_bucket.
+ */
+ a[i] = merge_pagelist(a[i], p);
+ }
+ }
+ p = a[0];
+ for(i=1; i<N_SORT_BUCKET; i++){
+ p = merge_pagelist(p, a[i]);
+ }
+ return p;
+}
+
+/*
+** Given a list of pages (connected by the PgHdr.pDirty pointer) write
+** every one of those pages out to the database file and mark them all
+** as clean.
+*/
+static int pager_write_pagelist(PgHdr *pList){
+ Pager *pPager;
+ PgHdr *p;
+ int rc;
+
+ if( pList==0 ) return SQLITE_OK;
+ pPager = pList->pPager;
+
+ /* At this point there may be either a RESERVED or EXCLUSIVE lock on the
+ ** database file. If there is already an EXCLUSIVE lock, the following
+ ** calls to sqlite3OsLock() are no-ops.
+ **
+ ** Moving the lock from RESERVED to EXCLUSIVE actually involves going
+ ** through an intermediate state PENDING. A PENDING lock prevents new
+ ** readers from attaching to the database but is unsufficient for us to
+ ** write. The idea of a PENDING lock is to prevent new readers from
+ ** coming in while we wait for existing readers to clear.
+ **
+ ** While the pager is in the RESERVED state, the original database file
+ ** is unchanged and we can rollback without having to playback the
+ ** journal into the original database file. Once we transition to
+ ** EXCLUSIVE, it means the database file has been changed and any rollback
+ ** will require a journal playback.
+ */
+ rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+
+ pList = sort_pagelist(pList);
+ for(p=pList; p; p=p->pDirty){
+ assert( p->dirty );
+ p->dirty = 0;
+ }
+ while( pList ){
+
+ /* If the file has not yet been opened, open it now. */
+ if( !pPager->fd->pMethods ){
+ assert(pPager->tempFile);
+ rc = sqlite3PagerOpentemp(pPager, pPager->fd, pPager->vfsFlags);
+ if( rc ) return rc;
+ }
+
+ /* If there are dirty pages in the page cache with page numbers greater
+ ** than Pager.dbSize, this means sqlite3PagerTruncate() was called to
+ ** make the file smaller (presumably by auto-vacuum code). Do not write
+ ** any such pages to the file.
+ */
+ if( pList->pgno<=pPager->dbSize ){
+ i64 offset = (pList->pgno-1)*(i64)pPager->pageSize;
+ char *pData = CODEC2(pPager, PGHDR_TO_DATA(pList), pList->pgno, 6);
+ PAGERTRACE4("STORE %d page %d hash(%08x)\n",
+ PAGERID(pPager), pList->pgno, pager_pagehash(pList));
+ IOTRACE(("PGOUT %p %d\n", pPager, pList->pgno));
+ rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize, offset);
+ PAGER_INCR(sqlite3_pager_writedb_count);
+ PAGER_INCR(pPager->nWrite);
+ if( pList->pgno==1 ){
+ memcpy(&pPager->dbFileVers, &pData[24], sizeof(pPager->dbFileVers));
+ }
+ }
+#ifndef NDEBUG
+ else{
+ PAGERTRACE3("NOSTORE %d page %d\n", PAGERID(pPager), pList->pgno);
+ }
+#endif
+ if( rc ) return rc;
+#ifdef SQLITE_CHECK_PAGES
+ pList->pageHash = pager_pagehash(pList);
+#endif
+ pList = pList->pDirty;
+ }
+ return SQLITE_OK;
+}
+
+/*
+** Collect every dirty page into a dirty list and
+** return a pointer to the head of that list. All pages are
+** collected even if they are still in use.
+*/
+static PgHdr *pager_get_all_dirty_pages(Pager *pPager){
+
+#ifndef NDEBUG
+ /* Verify the sanity of the dirty list when we are running
+ ** in debugging mode. This is expensive, so do not
+ ** do this on a normal build. */
+ int n1 = 0;
+ int n2 = 0;
+ PgHdr *p;
+ for(p=pPager->pAll; p; p=p->pNextAll){ if( p->dirty ) n1++; }
+ for(p=pPager->pDirty; p; p=p->pDirty){ n2++; }
+ assert( n1==n2 );
+#endif
+
+ return pPager->pDirty;
+}
+
+/*
+** Return 1 if there is a hot journal on the given pager.
+** A hot journal is one that needs to be played back.
+**
+** If the current size of the database file is 0 but a journal file
+** exists, that is probably an old journal left over from a prior
+** database with the same name. Just delete the journal.
+**
+** Return negative if unable to determine the status of the journal.
+**
+** This routine does not open the journal file to examine its
+** content. Hence, the journal might contain the name of a master
+** journal file that has been deleted, and hence not be hot. Or
+** the header of the journal might be zeroed out. This routine
+** does not discover these cases of a non-hot journal - if the
+** journal file exists and is not empty this routine assumes it
+** is hot. The pager_playback() routine will discover that the
+** journal file is not really hot and will no-op.
+*/
+static int hasHotJournal(Pager *pPager, int *pExists){
+ sqlite3_vfs *pVfs = pPager->pVfs;
+ int rc = SQLITE_OK;
+ *pExists = 0;
+ if( pPager->useJournal && pPager->fd->pMethods ){
+ int exists;
+ int locked;
+
+ rc = sqlite3OsAccess(pVfs, pPager->zJournal, SQLITE_ACCESS_EXISTS, &exists);
+ if( rc==SQLITE_OK && exists ){
+ rc = sqlite3OsCheckReservedLock(pPager->fd, &locked);
+ }
+
+ if( rc==SQLITE_OK && exists && !locked ){
+ int nPage;
+ rc = sqlite3PagerPagecount(pPager, &nPage);
+ if( rc==SQLITE_OK ){
+ if( nPage==0 ){
+ sqlite3OsDelete(pVfs, pPager->zJournal, 0);
+ }else{
+ *pExists = 1;
+ }
+ }
+ }
+ }
+
+ return rc;
+}
+
+/*
+** Try to find a page in the cache that can be recycled.
+**
+** This routine may return SQLITE_IOERR, SQLITE_FULL or SQLITE_OK. It
+** does not set the pPager->errCode variable.
+*/
+static int pager_recycle(Pager *pPager, PgHdr **ppPg){
+ PgHdr *pPg;
+ *ppPg = 0;
+
+ /* It is illegal to call this function unless the pager object
+ ** pointed to by pPager has at least one free page (page with nRef==0).
+ */
+ assert(!MEMDB);
+ assert(pPager->lru.pFirst);
+
+ /* Find a page to recycle. Try to locate a page that does not
+ ** require us to do an fsync() on the journal.
+ */
+ pPg = pPager->lru.pFirstSynced;
+
+ /* If we could not find a page that does not require an fsync()
+ ** on the journal file then fsync the journal file. This is a
+ ** very slow operation, so we work hard to avoid it. But sometimes
+ ** it can't be helped.
+ */
+ if( pPg==0 && pPager->lru.pFirst ){
+ if( !pPager->errCode ){
+ int iDc = sqlite3OsDeviceCharacteristics(pPager->fd);
+ int rc = syncJournal(pPager);
+ if( rc!=0 ){
+ return rc;
+ }
+ if( pPager->fullSync && 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
+ /* If in full-sync mode, write a new journal header into the
+ ** journal file. This is done to avoid ever modifying a journal
+ ** header that is involved in the rollback of pages that have
+ ** already been written to the database (in case the header is
+ ** trashed when the nRec field is updated).
+ */
+ pPager->nRec = 0;
+ assert( pPager->journalOff > 0 );
+ assert( pPager->doNotSync==0 );
+ rc = writeJournalHdr(pPager);
+ if( rc!=0 ){
+ return rc;
+ }
+ }
+ }
+ pPg = pPager->lru.pFirst;
+ }
+
+ assert( pPg->nRef==0 );
+
+ /* Write the page to the database file if it is dirty.
+ */
+ if( pPg->dirty && !pPager->errCode ){
+ int rc;
+ assert( pPg->needSync==0 );
+ makeClean(pPg);
+ pPg->dirty = 1;
+ pPg->pDirty = 0;
+ rc = pager_write_pagelist( pPg );
+ pPg->dirty = 0;
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ }
+ assert( pPg->dirty==0 || pPager->errCode );
+
+ /* If the page we are recycling is marked as alwaysRollback, then
+ ** set the global alwaysRollback flag, thus disabling the
+ ** sqlite3PagerDontRollback() optimization for the rest of this transaction.
+ ** It is necessary to do this because the page marked alwaysRollback
+ ** might be reloaded at a later time but at that point we won't remember
+ ** that is was marked alwaysRollback. This means that all pages must
+ ** be marked as alwaysRollback from here on out.
+ */
+ if( pPg->alwaysRollback ){
+ IOTRACE(("ALWAYS_ROLLBACK %p\n", pPager))
+ pPager->alwaysRollback = 1;
+ }
+
+ /* Unlink the old page from the free list and the hash table
+ */
+ unlinkPage(pPg);
+ assert( pPg->pgno==0 );
+
+ *ppPg = pPg;
+ return SQLITE_OK;
+}
+
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+/*
+** This function is called to free superfluous dynamically allocated memory
+** held by the pager system. Memory in use by any SQLite pager allocated
+** by the current thread may be sqlite3_free()ed.
+**
+** nReq is the number of bytes of memory required. Once this much has
+** been released, the function returns. The return value is the total number
+** of bytes of memory released.
+*/
+int sqlite3PagerReleaseMemory(int nReq){
+ int nReleased = 0; /* Bytes of memory released so far */
+ Pager *pPager; /* For looping over pagers */
+ BusyHandler *savedBusy; /* Saved copy of the busy handler */
+ int rc = SQLITE_OK;
+
+ /* Acquire the memory-management mutex
+ */
+#ifndef SQLITE_MUTEX_NOOP
+ sqlite3_mutex *mutex; /* The MEM2 mutex */
+ mutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_MEM2);
+#endif
+ sqlite3_mutex_enter(mutex);
+
+ /* Signal all database connections that memory management wants
+ ** to have access to the pagers.
+ */
+ for(pPager=sqlite3PagerList; pPager; pPager=pPager->pNext){
+ pPager->iInUseMM = 1;
+ }
+
+ while( rc==SQLITE_OK && (nReq<0 || nReleased<nReq) ){
+ PgHdr *pPg;
+ PgHdr *pRecycled;
+
+ /* Try to find a page to recycle that does not require a sync(). If
+ ** this is not possible, find one that does require a sync().
+ */
+ sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU));
+ pPg = sqlite3LruPageList.pFirstSynced;
+ while( pPg && (pPg->needSync || pPg->pPager->iInUseDB) ){
+ pPg = pPg->gfree.pNext;
+ }
+ if( !pPg ){
+ pPg = sqlite3LruPageList.pFirst;
+ while( pPg && pPg->pPager->iInUseDB ){
+ pPg = pPg->gfree.pNext;
+ }
+ }
+ sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU));
+
+ /* If pPg==0, then the block above has failed to find a page to
+ ** recycle. In this case return early - no further memory will
+ ** be released.
+ */
+ if( !pPg ) break;
+
+ pPager = pPg->pPager;
+ assert(!pPg->needSync || pPg==pPager->lru.pFirst);
+ assert(pPg->needSync || pPg==pPager->lru.pFirstSynced);
+
+ savedBusy = pPager->pBusyHandler;
+ pPager->pBusyHandler = 0;
+ rc = pager_recycle(pPager, &pRecycled);
+ pPager->pBusyHandler = savedBusy;
+ assert(pRecycled==pPg || rc!=SQLITE_OK);
+ if( rc==SQLITE_OK ){
+ /* We've found a page to free. At this point the page has been
+ ** removed from the page hash-table, free-list and synced-list
+ ** (pFirstSynced). It is still in the all pages (pAll) list.
+ ** Remove it from this list before freeing.
+ **
+ ** Todo: Check the Pager.pStmt list to make sure this is Ok. It
+ ** probably is though.
+ */
+ PgHdr *pTmp;
+ assert( pPg );
+ if( pPg==pPager->pAll ){
+ assert(pPg->pPrevAll==0);
+ assert(pPg->pNextAll==0 || pPg->pNextAll->pPrevAll==pPg);
+ pPager->pAll = pPg->pNextAll;
+ if( pPager->pAll ){
+ pPager->pAll->pPrevAll = 0;
+ }
+ }else{
+ assert(pPg->pPrevAll);
+ assert(pPg->pPrevAll->pNextAll==pPg);
+ pTmp = pPg->pPrevAll;
+ pTmp->pNextAll = pPg->pNextAll;
+ if( pTmp->pNextAll ){
+ pTmp->pNextAll->pPrevAll = pTmp;
+ }
+ }
+ nReleased += (
+ sizeof(*pPg) + pPager->pageSize
+ + sizeof(u32) + pPager->nExtra
+ + MEMDB*sizeof(PgHistory)
+ );
+ IOTRACE(("PGFREE %p %d *\n", pPager, pPg->pgno));
+ PAGER_INCR(sqlite3_pager_pgfree_count);
+ sqlite3PageFree(pPg->pData);
+ sqlite3_free(pPg);
+ pPager->nPage--;
+ }else{
+ /* An error occured whilst writing to the database file or
+ ** journal in pager_recycle(). The error is not returned to the
+ ** caller of this function. Instead, set the Pager.errCode variable.
+ ** The error will be returned to the user (or users, in the case
+ ** of a shared pager cache) of the pager for which the error occured.
+ */
+ assert(
+ (rc&0xff)==SQLITE_IOERR ||
+ rc==SQLITE_FULL ||
+ rc==SQLITE_BUSY
+ );
+ assert( pPager->state>=PAGER_RESERVED );
+ pager_error(pPager, rc);
+ }
+ }
+
+ /* Clear the memory management flags and release the mutex
+ */
+ for(pPager=sqlite3PagerList; pPager; pPager=pPager->pNext){
+ pPager->iInUseMM = 0;
+ }
+ sqlite3_mutex_leave(mutex);
+
+ /* Return the number of bytes released
+ */
+ return nReleased;
+}
+#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */
+
+/*
+** Read the content of page pPg out of the database file.
+*/
+static int readDbPage(Pager *pPager, PgHdr *pPg, Pgno pgno){
+ int rc;
+ i64 offset;
+ assert( MEMDB==0 );
+ assert(pPager->fd->pMethods||pPager->tempFile);
+ if( !pPager->fd->pMethods ){
+ return SQLITE_IOERR_SHORT_READ;
+ }
+ offset = (pgno-1)*(i64)pPager->pageSize;
+ rc = sqlite3OsRead(pPager->fd, PGHDR_TO_DATA(pPg), pPager->pageSize, offset);
+ PAGER_INCR(sqlite3_pager_readdb_count);
+ PAGER_INCR(pPager->nRead);
+ IOTRACE(("PGIN %p %d\n", pPager, pgno));
+ if( pgno==1 ){
+ memcpy(&pPager->dbFileVers, &((u8*)PGHDR_TO_DATA(pPg))[24],
+ sizeof(pPager->dbFileVers));
+ }
+ CODEC1(pPager, PGHDR_TO_DATA(pPg), pPg->pgno, 3);
+ PAGERTRACE4("FETCH %d page %d hash(%08x)\n",
+ PAGERID(pPager), pPg->pgno, pager_pagehash(pPg));
+ return rc;
+}
+
+
+/*
+** This function is called to obtain the shared lock required before
+** data may be read from the pager cache. If the shared lock has already
+** been obtained, this function is a no-op.
+**
+** Immediately after obtaining the shared lock (if required), this function
+** checks for a hot-journal file. If one is found, an emergency rollback
+** is performed immediately.
+*/
+static int pagerSharedLock(Pager *pPager){
+ int rc = SQLITE_OK;
+ int isErrorReset = 0;
+
+ /* If this database is opened for exclusive access, has no outstanding
+ ** page references and is in an error-state, now is the chance to clear
+ ** the error. Discard the contents of the pager-cache and treat any
+ ** open journal file as a hot-journal.
+ */
+ if( !MEMDB && pPager->exclusiveMode && pPager->nRef==0 && pPager->errCode ){
+ if( pPager->journalOpen ){
+ isErrorReset = 1;
+ }
+ pPager->errCode = SQLITE_OK;
+ pager_reset(pPager);
+ }
+
+ /* If the pager is still in an error state, do not proceed. The error
+ ** state will be cleared at some point in the future when all page
+ ** references are dropped and the cache can be discarded.
+ */
+ if( pPager->errCode && pPager->errCode!=SQLITE_FULL ){
+ return pPager->errCode;
+ }
+
+ if( pPager->state==PAGER_UNLOCK || isErrorReset ){
+ sqlite3_vfs *pVfs = pPager->pVfs;
+ if( !MEMDB ){
+ int isHotJournal;
+ assert( pPager->nRef==0 );
+ if( !pPager->noReadlock ){
+ rc = pager_wait_on_lock(pPager, SHARED_LOCK);
+ if( rc!=SQLITE_OK ){
+ assert( pPager->state==PAGER_UNLOCK );
+ return pager_error(pPager, rc);
+ }
+ assert( pPager->state>=SHARED_LOCK );
+ }
+
+ /* If a journal file exists, and there is no RESERVED lock on the
+ ** database file, then it either needs to be played back or deleted.
+ */
+ if( !isErrorReset ){
+ rc = hasHotJournal(pPager, &isHotJournal);
+ if( rc!=SQLITE_OK ){
+ goto failed;
+ }
+ }
+ if( isErrorReset || isHotJournal ){
+ /* Get an EXCLUSIVE lock on the database file. At this point it is
+ ** important that a RESERVED lock is not obtained on the way to the
+ ** EXCLUSIVE lock. If it were, another process might open the
+ ** database file, detect the RESERVED lock, and conclude that the
+ ** database is safe to read while this process is still rolling it
+ ** back.
+ **
+ ** Because the intermediate RESERVED lock is not requested, the
+ ** second process will get to this point in the code and fail to
+ ** obtain its own EXCLUSIVE lock on the database file.
+ */
+ if( pPager->state<EXCLUSIVE_LOCK ){
+ rc = sqlite3OsLock(pPager->fd, EXCLUSIVE_LOCK);
+ if( rc!=SQLITE_OK ){
+ rc = pager_error(pPager, rc);
+ goto failed;
+ }
+ pPager->state = PAGER_EXCLUSIVE;
+ }
+
+ /* Open the journal for read/write access. This is because in
+ ** exclusive-access mode the file descriptor will be kept open and
+ ** possibly used for a transaction later on. On some systems, the
+ ** OsTruncate() call used in exclusive-access mode also requires
+ ** a read/write file handle.
+ */
+ if( !isErrorReset && pPager->journalOpen==0 ){
+ int res;
+ rc = sqlite3OsAccess(pVfs,pPager->zJournal,SQLITE_ACCESS_EXISTS,&res);
+ if( rc==SQLITE_OK ){
+ if( res ){
+ int fout = 0;
+ int f = SQLITE_OPEN_READWRITE|SQLITE_OPEN_MAIN_JOURNAL;
+ assert( !pPager->tempFile );
+ rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, f, &fout);
+ assert( rc!=SQLITE_OK || pPager->jfd->pMethods );
+ if( fout&SQLITE_OPEN_READONLY ){
+ rc = SQLITE_BUSY;
+ sqlite3OsClose(pPager->jfd);
+ }
+ }else{
+ /* If the journal does not exist, that means some other process
+ ** has already rolled it back */
+ rc = SQLITE_BUSY;
+ }
+ }
+ }
+ if( rc!=SQLITE_OK ){
+ if( rc!=SQLITE_NOMEM && rc!=SQLITE_IOERR_UNLOCK
+ && rc!=SQLITE_IOERR_NOMEM
+ ){
+ rc = SQLITE_BUSY;
+ }
+ goto failed;
+ }
+ pPager->journalOpen = 1;
+ pPager->journalStarted = 0;
+ pPager->journalOff = 0;
+ pPager->setMaster = 0;
+ pPager->journalHdr = 0;
+
+ /* Playback and delete the journal. Drop the database write
+ ** lock and reacquire the read lock.
+ */
+ rc = pager_playback(pPager, 1);
+ if( rc!=SQLITE_OK ){
+ rc = pager_error(pPager, rc);
+ goto failed;
+ }
+ assert(pPager->state==PAGER_SHARED ||
+ (pPager->exclusiveMode && pPager->state>PAGER_SHARED)
+ );
+ }
+
+ if( pPager->pAll ){
+ /* The shared-lock has just been acquired on the database file
+ ** and there are already pages in the cache (from a previous
+ ** read or write transaction). Check to see if the database
+ ** has been modified. If the database has changed, flush the
+ ** cache.
+ **
+ ** Database changes is detected by looking at 15 bytes beginning
+ ** at offset 24 into the file. The first 4 of these 16 bytes are
+ ** a 32-bit counter that is incremented with each change. The
+ ** other bytes change randomly with each file change when
+ ** a codec is in use.
+ **
+ ** There is a vanishingly small chance that a change will not be
+ ** detected. The chance of an undetected change is so small that
+ ** it can be neglected.
+ */
+ char dbFileVers[sizeof(pPager->dbFileVers)];
+ sqlite3PagerPagecount(pPager, 0);
+
+ if( pPager->errCode ){
+ rc = pPager->errCode;
+ goto failed;
+ }
+
+ if( pPager->dbSize>0 ){
+ IOTRACE(("CKVERS %p %d\n", pPager, sizeof(dbFileVers)));
+ rc = sqlite3OsRead(pPager->fd, &dbFileVers, sizeof(dbFileVers), 24);
+ if( rc!=SQLITE_OK ){
+ goto failed;
+ }
+ }else{
+ memset(dbFileVers, 0, sizeof(dbFileVers));
+ }
+
+ if( memcmp(pPager->dbFileVers, dbFileVers, sizeof(dbFileVers))!=0 ){
+ pager_reset(pPager);
+ }
+ }
+ }
+ assert( pPager->exclusiveMode || pPager->state<=PAGER_SHARED );
+ if( pPager->state==PAGER_UNLOCK ){
+ pPager->state = PAGER_SHARED;
+ }
+ }
+
+ failed:
+ if( rc!=SQLITE_OK ){
+ /* pager_unlock() is a no-op for exclusive mode and in-memory databases. */
+ pager_unlock(pPager);
+ }
+ return rc;
+}
+
+/*
+** Allocate a PgHdr object. Either create a new one or reuse
+** an existing one that is not otherwise in use.
+**
+** A new PgHdr structure is created if any of the following are
+** true:
+**
+** (1) We have not exceeded our maximum allocated cache size
+** as set by the "PRAGMA cache_size" command.
+**
+** (2) There are no unused PgHdr objects available at this time.
+**
+** (3) This is an in-memory database.
+**
+** (4) There are no PgHdr objects that do not require a journal
+** file sync and a sync of the journal file is currently
+** prohibited.
+**
+** Otherwise, reuse an existing PgHdr. In other words, reuse an
+** existing PgHdr if all of the following are true:
+**
+** (1) We have reached or exceeded the maximum cache size
+** allowed by "PRAGMA cache_size".
+**
+** (2) There is a PgHdr available with PgHdr->nRef==0
+**
+** (3) We are not in an in-memory database
+**
+** (4) Either there is an available PgHdr that does not need
+** to be synced to disk or else disk syncing is currently
+** allowed.
+*/
+static int pagerAllocatePage(Pager *pPager, PgHdr **ppPg){
+ int rc = SQLITE_OK;
+ PgHdr *pPg;
+ int nByteHdr;
+
+ /* Create a new PgHdr if any of the four conditions defined
+ ** above are met: */
+ if( pPager->nPage<pPager->mxPage
+ || pPager->lru.pFirst==0
+ || MEMDB
+ || (pPager->lru.pFirstSynced==0 && pPager->doNotSync)
+ ){
+ void *pData;
+ if( pPager->nPage>=pPager->nHash ){
+ pager_resize_hash_table(pPager,
+ pPager->nHash<256 ? 256 : pPager->nHash*2);
+ if( pPager->nHash==0 ){
+ rc = SQLITE_NOMEM;
+ goto pager_allocate_out;
+ }
+ }
+ pagerLeave(pPager);
+ nByteHdr = sizeof(*pPg) + sizeof(u32) + pPager->nExtra
+ + MEMDB*sizeof(PgHistory);
+ pPg = sqlite3Malloc( nByteHdr );
+ if( pPg ){
+ pData = sqlite3PageMalloc( pPager->pageSize );
+ if( pData==0 ){
+ sqlite3_free(pPg);
+ pPg = 0;
+ }
+ }
+ pagerEnter(pPager);
+ if( pPg==0 ){
+ rc = SQLITE_NOMEM;
+ goto pager_allocate_out;
+ }
+ memset(pPg, 0, nByteHdr);
+ pPg->pData = pData;
+ pPg->pPager = pPager;
+ pPg->pNextAll = pPager->pAll;
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ if( pPg->pNextAll ){
+ pPg->pNextAll->pPrevAll = pPg;
+ }
+#endif
+ pPager->pAll = pPg;
+ pPager->nPage++;
+ }else{
+ /* Recycle an existing page with a zero ref-count. */
+ rc = pager_recycle(pPager, &pPg);
+ if( rc==SQLITE_BUSY ){
+ rc = SQLITE_IOERR_BLOCKED;
+ }
+ if( rc!=SQLITE_OK ){
+ goto pager_allocate_out;
+ }
+ assert( pPager->state>=SHARED_LOCK );
+ assert(pPg);
+ }
+ *ppPg = pPg;
+
+pager_allocate_out:
+ return rc;
+}
+
+/*
+** Make sure we have the content for a page. If the page was
+** previously acquired with noContent==1, then the content was
+** just initialized to zeros instead of being read from disk.
+** But now we need the real data off of disk. So make sure we
+** have it. Read it in if we do not have it already.
+*/
+static int pager_get_content(PgHdr *pPg){
+ if( pPg->needRead ){
+ int rc = readDbPage(pPg->pPager, pPg, pPg->pgno);
+ if( rc==SQLITE_OK ){
+ pPg->needRead = 0;
+ }else{
+ return rc;
+ }
+ }
+ return SQLITE_OK;
+}
+
+/*
+** Acquire a page.
+**
+** A read lock on the disk file is obtained when the first page is acquired.
+** This read lock is dropped when the last page is released.
+**
+** This routine works for any page number greater than 0. If the database
+** file is smaller than the requested page, then no actual disk
+** read occurs and the memory image of the page is initialized to
+** all zeros. The extra data appended to a page is always initialized
+** to zeros the first time a page is loaded into memory.
+**
+** The acquisition might fail for several reasons. In all cases,
+** an appropriate error code is returned and *ppPage is set to NULL.
+**
+** See also sqlite3PagerLookup(). Both this routine and Lookup() attempt
+** to find a page in the in-memory cache first. If the page is not already
+** in memory, this routine goes to disk to read it in whereas Lookup()
+** just returns 0. This routine acquires a read-lock the first time it
+** has to go to disk, and could also playback an old journal if necessary.
+** Since Lookup() never goes to disk, it never has to deal with locks
+** or journal files.
+**
+** If noContent is false, the page contents are actually read from disk.
+** If noContent is true, it means that we do not care about the contents
+** of the page at this time, so do not do a disk read. Just fill in the
+** page content with zeros. But mark the fact that we have not read the
+** content by setting the PgHdr.needRead flag. Later on, if
+** sqlite3PagerWrite() is called on this page or if this routine is
+** called again with noContent==0, that means that the content is needed
+** and the disk read should occur at that point.
+*/
+static int pagerAcquire(
+ Pager *pPager, /* The pager open on the database file */
+ Pgno pgno, /* Page number to fetch */
+ DbPage **ppPage, /* Write a pointer to the page here */
+ int noContent /* Do not bother reading content from disk if true */
+){
+ PgHdr *pPg;
+ int rc;
+
+ assert( pPager->state==PAGER_UNLOCK || pPager->nRef>0 || pgno==1 );
+
+ /* The maximum page number is 2^31. Return SQLITE_CORRUPT if a page
+ ** number greater than this, or zero, is requested.
+ */
+ if( pgno>PAGER_MAX_PGNO || pgno==0 || pgno==PAGER_MJ_PGNO(pPager) ){
+ return SQLITE_CORRUPT_BKPT;
+ }
+
+ /* Make sure we have not hit any critical errors.
+ */
+ assert( pPager!=0 );
+ *ppPage = 0;
+
+ /* If this is the first page accessed, then get a SHARED lock
+ ** on the database file. pagerSharedLock() is a no-op if
+ ** a database lock is already held.
+ */
+ rc = pagerSharedLock(pPager);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ assert( pPager->state!=PAGER_UNLOCK );
+
+ pPg = pager_lookup(pPager, pgno);
+ if( pPg==0 ){
+ /* The requested page is not in the page cache. */
+ int nMax;
+ int h;
+ PAGER_INCR(pPager->nMiss);
+ rc = pagerAllocatePage(pPager, &pPg);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+
+ pPg->pgno = pgno;
+ assert( !MEMDB || pgno>pPager->stmtSize );
+ pPg->inJournal = sqlite3BitvecTest(pPager->pInJournal, pgno);
+ pPg->needSync = 0;
+
+ makeClean(pPg);
+ pPg->nRef = 1;
+
+ pPager->nRef++;
+ if( pPager->nExtra>0 ){
+ memset(PGHDR_TO_EXTRA(pPg, pPager), 0, pPager->nExtra);
+ }
+ rc = sqlite3PagerPagecount(pPager, &nMax);
+ if( rc!=SQLITE_OK ){
+ sqlite3PagerUnref(pPg);
+ return rc;
+ }
+
+ /* Populate the page with data, either by reading from the database
+ ** file, or by setting the entire page to zero.
+ */
+ if( nMax<(int)pgno || MEMDB || (noContent && !pPager->alwaysRollback) ){
+ if( pgno>pPager->mxPgno ){
+ sqlite3PagerUnref(pPg);
+ return SQLITE_FULL;
+ }
+ memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
+ pPg->needRead = noContent && !pPager->alwaysRollback;
+ IOTRACE(("ZERO %p %d\n", pPager, pgno));
+ }else{
+ rc = readDbPage(pPager, pPg, pgno);
+ if( rc!=SQLITE_OK && rc!=SQLITE_IOERR_SHORT_READ ){
+ pPg->pgno = 0;
+ sqlite3PagerUnref(pPg);
+ return rc;
+ }
+ pPg->needRead = 0;
+ }
+
+ /* Link the page into the page hash table */
+ h = pgno & (pPager->nHash-1);
+ assert( pgno!=0 );
+ pPg->pNextHash = pPager->aHash[h];
+ pPager->aHash[h] = pPg;
+ if( pPg->pNextHash ){
+ assert( pPg->pNextHash->pPrevHash==0 );
+ pPg->pNextHash->pPrevHash = pPg;
+ }
+
+#ifdef SQLITE_CHECK_PAGES
+ pPg->pageHash = pager_pagehash(pPg);
+#endif
+ }else{
+ /* The requested page is in the page cache. */
+ assert(pPager->nRef>0 || pgno==1);
+ PAGER_INCR(pPager->nHit);
+ if( !noContent ){
+ rc = pager_get_content(pPg);
+ if( rc ){
+ return rc;
+ }
+ }
+ page_ref(pPg);
+ }
+ *ppPage = pPg;
+ return SQLITE_OK;
+}
+int sqlite3PagerAcquire(
+ Pager *pPager, /* The pager open on the database file */
+ Pgno pgno, /* Page number to fetch */
+ DbPage **ppPage, /* Write a pointer to the page here */
+ int noContent /* Do not bother reading content from disk if true */
+){
+ int rc;
+ pagerEnter(pPager);
+ rc = pagerAcquire(pPager, pgno, ppPage, noContent);
+ pagerLeave(pPager);
+ return rc;
+}
+
+
+/*
+** Acquire a page if it is already in the in-memory cache. Do
+** not read the page from disk. Return a pointer to the page,
+** or 0 if the page is not in cache.
+**
+** See also sqlite3PagerGet(). The difference between this routine
+** and sqlite3PagerGet() is that _get() will go to the disk and read
+** in the page if the page is not already in cache. This routine
+** returns NULL if the page is not in cache or if a disk I/O error
+** has ever happened.
+*/
+DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno){
+ PgHdr *pPg = 0;
+
+ assert( pPager!=0 );
+ assert( pgno!=0 );
+
+ pagerEnter(pPager);
+ if( pPager->state==PAGER_UNLOCK ){
+ assert( !pPager->pAll || pPager->exclusiveMode );
+ }else if( pPager->errCode && pPager->errCode!=SQLITE_FULL ){
+ /* Do nothing */
+ }else if( (pPg = pager_lookup(pPager, pgno))!=0 ){
+ page_ref(pPg);
+ }
+ pagerLeave(pPager);
+ return pPg;
+}
+
+/*
+** Release a page.
+**
+** If the number of references to the page drop to zero, then the
+** page is added to the LRU list. When all references to all pages
+** are released, a rollback occurs and the lock on the database is
+** removed.
+*/
+int sqlite3PagerUnref(DbPage *pPg){
+ Pager *pPager;
+
+ if( pPg==0 ) return SQLITE_OK;
+ pPager = pPg->pPager;
+
+ /* Decrement the reference count for this page
+ */
+ assert( pPg->nRef>0 );
+ pagerEnter(pPg->pPager);
+ pPg->nRef--;
+
+ CHECK_PAGE(pPg);
+
+ /* When the number of references to a page reach 0, call the
+ ** destructor and add the page to the freelist.
+ */
+ if( pPg->nRef==0 ){
+
+ lruListAdd(pPg);
+ if( pPager->xDestructor ){
+ pPager->xDestructor(pPg, pPager->pageSize);
+ }
+
+ /* When all pages reach the freelist, drop the read lock from
+ ** the database file.
+ */
+ pPager->nRef--;
+ assert( pPager->nRef>=0 );
+ if( pPager->nRef==0 && (!pPager->exclusiveMode || pPager->journalOff>0) ){
+ pagerUnlockAndRollback(pPager);
+ }
+ }
+ pagerLeave(pPager);
+ return SQLITE_OK;
+}
+
+/*
+** Create a journal file for pPager. There should already be a RESERVED
+** or EXCLUSIVE lock on the database file when this routine is called.
+**
+** Return SQLITE_OK if everything. Return an error code and release the
+** write lock if anything goes wrong.
+*/
+static int pager_open_journal(Pager *pPager){
+ sqlite3_vfs *pVfs = pPager->pVfs;
+ int flags = (SQLITE_OPEN_READWRITE|SQLITE_OPEN_EXCLUSIVE|SQLITE_OPEN_CREATE);
+
+ int rc;
+ assert( !MEMDB );
+ assert( pPager->state>=PAGER_RESERVED );
+ assert( pPager->useJournal );
+ assert( pPager->pInJournal==0 );
+ sqlite3PagerPagecount(pPager, 0);
+ pagerLeave(pPager);
+ pPager->pInJournal = sqlite3BitvecCreate(pPager->dbSize);
+ pagerEnter(pPager);
+ if( pPager->pInJournal==0 ){
+ rc = SQLITE_NOMEM;
+ goto failed_to_open_journal;
+ }
+
+ if( pPager->journalOpen==0 ){
+ if( pPager->tempFile ){
+ flags |= (SQLITE_OPEN_DELETEONCLOSE|SQLITE_OPEN_TEMP_JOURNAL);
+ }else{
+ flags |= (SQLITE_OPEN_MAIN_JOURNAL);
+ }
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+ rc = sqlite3JournalOpen(
+ pVfs, pPager->zJournal, pPager->jfd, flags, jrnlBufferSize(pPager)
+ );
+#else
+ rc = sqlite3OsOpen(pVfs, pPager->zJournal, pPager->jfd, flags, 0);
+#endif
+ assert( rc!=SQLITE_OK || pPager->jfd->pMethods );
+ pPager->journalOff = 0;
+ pPager->setMaster = 0;
+ pPager->journalHdr = 0;
+ if( rc!=SQLITE_OK ){
+ if( rc==SQLITE_NOMEM ){
+ sqlite3OsDelete(pVfs, pPager->zJournal, 0);
+ }
+ goto failed_to_open_journal;
+ }
+ }
+ pPager->journalOpen = 1;
+ pPager->journalStarted = 0;
+ pPager->needSync = 0;
+ pPager->alwaysRollback = 0;
+ pPager->nRec = 0;
+ if( pPager->errCode ){
+ rc = pPager->errCode;
+ goto failed_to_open_journal;
+ }
+ pPager->origDbSize = pPager->dbSize;
+
+ rc = writeJournalHdr(pPager);
+
+ if( pPager->stmtAutoopen && rc==SQLITE_OK ){
+ rc = sqlite3PagerStmtBegin(pPager);
+ }
+ if( rc!=SQLITE_OK && rc!=SQLITE_NOMEM && rc!=SQLITE_IOERR_NOMEM ){
+ rc = pager_end_transaction(pPager, 0);
+ if( rc==SQLITE_OK ){
+ rc = SQLITE_FULL;
+ }
+ }
+ return rc;
+
+failed_to_open_journal:
+ sqlite3BitvecDestroy(pPager->pInJournal);
+ pPager->pInJournal = 0;
+ return rc;
+}
+
+/*
+** Acquire a write-lock on the database. The lock is removed when
+** the any of the following happen:
+**
+** * sqlite3PagerCommitPhaseTwo() is called.
+** * sqlite3PagerRollback() is called.
+** * sqlite3PagerClose() is called.
+** * sqlite3PagerUnref() is called to on every outstanding page.
+**
+** The first parameter to this routine is a pointer to any open page of the
+** database file. Nothing changes about the page - it is used merely to
+** acquire a pointer to the Pager structure and as proof that there is
+** already a read-lock on the database.
+**
+** The second parameter indicates how much space in bytes to reserve for a
+** master journal file-name at the start of the journal when it is created.
+**
+** A journal file is opened if this is not a temporary file. For temporary
+** files, the opening of the journal file is deferred until there is an
+** actual need to write to the journal.
+**
+** If the database is already reserved for writing, this routine is a no-op.
+**
+** If exFlag is true, go ahead and get an EXCLUSIVE lock on the file
+** immediately instead of waiting until we try to flush the cache. The
+** exFlag is ignored if a transaction is already active.
+*/
+int sqlite3PagerBegin(DbPage *pPg, int exFlag){
+ Pager *pPager = pPg->pPager;
+ int rc = SQLITE_OK;
+ pagerEnter(pPager);
+ assert( pPg->nRef>0 );
+ assert( pPager->state!=PAGER_UNLOCK );
+ if( pPager->state==PAGER_SHARED ){
+ assert( pPager->pInJournal==0 );
+ if( MEMDB ){
+ pPager->state = PAGER_EXCLUSIVE;
+ pPager->origDbSize = pPager->dbSize;
+ }else{
+ rc = sqlite3OsLock(pPager->fd, RESERVED_LOCK);
+ if( rc==SQLITE_OK ){
+ pPager->state = PAGER_RESERVED;
+ if( exFlag ){
+ rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
+ }
+ }
+ if( rc!=SQLITE_OK ){
+ pagerLeave(pPager);
+ return rc;
+ }
+ pPager->dirtyCache = 0;
+ PAGERTRACE2("TRANSACTION %d\n", PAGERID(pPager));
+ if( pPager->useJournal && !pPager->tempFile
+ && pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
+ rc = pager_open_journal(pPager);
+ }
+ }
+ }else if( pPager->journalOpen && pPager->journalOff==0 ){
+ /* This happens when the pager was in exclusive-access mode the last
+ ** time a (read or write) transaction was successfully concluded
+ ** by this connection. Instead of deleting the journal file it was
+ ** kept open and either was truncated to 0 bytes or its header was
+ ** overwritten with zeros.
+ */
+ assert( pPager->nRec==0 );
+ assert( pPager->origDbSize==0 );
+ assert( pPager->pInJournal==0 );
+ sqlite3PagerPagecount(pPager, 0);
+ pagerLeave(pPager);
+ pPager->pInJournal = sqlite3BitvecCreate( pPager->dbSize );
+ pagerEnter(pPager);
+ if( !pPager->pInJournal ){
+ rc = SQLITE_NOMEM;
+ }else{
+ pPager->origDbSize = pPager->dbSize;
+ rc = writeJournalHdr(pPager);
+ }
+ }
+ assert( !pPager->journalOpen || pPager->journalOff>0 || rc!=SQLITE_OK );
+ pagerLeave(pPager);
+ return rc;
+}
+
+/*
+** Make a page dirty. Set its dirty flag and add it to the dirty
+** page list.
+*/
+static void makeDirty(PgHdr *pPg){
+ if( pPg->dirty==0 ){
+ Pager *pPager = pPg->pPager;
+ pPg->dirty = 1;
+ pPg->pDirty = pPager->pDirty;
+ if( pPager->pDirty ){
+ pPager->pDirty->pPrevDirty = pPg;
+ }
+ pPg->pPrevDirty = 0;
+ pPager->pDirty = pPg;
+ }
+}
+
+/*
+** Make a page clean. Clear its dirty bit and remove it from the
+** dirty page list.
+*/
+static void makeClean(PgHdr *pPg){
+ if( pPg->dirty ){
+ pPg->dirty = 0;
+ if( pPg->pDirty ){
+ assert( pPg->pDirty->pPrevDirty==pPg );
+ pPg->pDirty->pPrevDirty = pPg->pPrevDirty;
+ }
+ if( pPg->pPrevDirty ){
+ assert( pPg->pPrevDirty->pDirty==pPg );
+ pPg->pPrevDirty->pDirty = pPg->pDirty;
+ }else{
+ assert( pPg->pPager->pDirty==pPg );
+ pPg->pPager->pDirty = pPg->pDirty;
+ }
+ }
+}
+
+
+/*
+** Mark a data page as writeable. The page is written into the journal
+** if it is not there already. This routine must be called before making
+** changes to a page.
+**
+** The first time this routine is called, the pager creates a new
+** journal and acquires a RESERVED lock on the database. If the RESERVED
+** lock could not be acquired, this routine returns SQLITE_BUSY. The
+** calling routine must check for that return value and be careful not to
+** change any page data until this routine returns SQLITE_OK.
+**
+** If the journal file could not be written because the disk is full,
+** then this routine returns SQLITE_FULL and does an immediate rollback.
+** All subsequent write attempts also return SQLITE_FULL until there
+** is a call to sqlite3PagerCommit() or sqlite3PagerRollback() to
+** reset.
+*/
+static int pager_write(PgHdr *pPg){
+ void *pData = PGHDR_TO_DATA(pPg);
+ Pager *pPager = pPg->pPager;
+ int rc = SQLITE_OK;
+
+ /* Check for errors
+ */
+ if( pPager->errCode ){
+ return pPager->errCode;
+ }
+ if( pPager->readOnly ){
+ return SQLITE_PERM;
+ }
+
+ assert( !pPager->setMaster );
+
+ CHECK_PAGE(pPg);
+
+ /* If this page was previously acquired with noContent==1, that means
+ ** we didn't really read in the content of the page. This can happen
+ ** (for example) when the page is being moved to the freelist. But
+ ** now we are (perhaps) moving the page off of the freelist for
+ ** reuse and we need to know its original content so that content
+ ** can be stored in the rollback journal. So do the read at this
+ ** time.
+ */
+ rc = pager_get_content(pPg);
+ if( rc ){
+ return rc;
+ }
+
+ /* Mark the page as dirty. If the page has already been written
+ ** to the journal then we can return right away.
+ */
+ makeDirty(pPg);
+ if( pPg->inJournal && (pageInStatement(pPg) || pPager->stmtInUse==0) ){
+ pPager->dirtyCache = 1;
+ pPager->dbModified = 1;
+ }else{
+
+ /* If we get this far, it means that the page needs to be
+ ** written to the transaction journal or the ckeckpoint journal
+ ** or both.
+ **
+ ** First check to see that the transaction journal exists and
+ ** create it if it does not.
+ */
+ assert( pPager->state!=PAGER_UNLOCK );
+ rc = sqlite3PagerBegin(pPg, 0);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ assert( pPager->state>=PAGER_RESERVED );
+ if( !pPager->journalOpen && pPager->useJournal
+ && pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
+ rc = pager_open_journal(pPager);
+ if( rc!=SQLITE_OK ) return rc;
+ }
+ pPager->dirtyCache = 1;
+ pPager->dbModified = 1;
+
+ /* The transaction journal now exists and we have a RESERVED or an
+ ** EXCLUSIVE lock on the main database file. Write the current page to
+ ** the transaction journal if it is not there already.
+ */
+ if( !pPg->inJournal && (pPager->journalOpen || MEMDB) ){
+ if( (int)pPg->pgno <= pPager->origDbSize ){
+ if( MEMDB ){
+ PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager);
+ PAGERTRACE3("JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
+ assert( pHist->pOrig==0 );
+ pHist->pOrig = sqlite3PageMalloc( pPager->pageSize );
+ if( !pHist->pOrig ){
+ return SQLITE_NOMEM;
+ }
+ memcpy(pHist->pOrig, PGHDR_TO_DATA(pPg), pPager->pageSize);
+ }else{
+ u32 cksum;
+ char *pData2;
+
+ /* We should never write to the journal file the page that
+ ** contains the database locks. The following assert verifies
+ ** that we do not. */
+ assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );
+ pData2 = CODEC2(pPager, pData, pPg->pgno, 7);
+ cksum = pager_cksum(pPager, (u8*)pData2);
+ rc = write32bits(pPager->jfd, pPager->journalOff, pPg->pgno);
+ if( rc==SQLITE_OK ){
+ rc = sqlite3OsWrite(pPager->jfd, pData2, pPager->pageSize,
+ pPager->journalOff + 4);
+ pPager->journalOff += pPager->pageSize+4;
+ }
+ if( rc==SQLITE_OK ){
+ rc = write32bits(pPager->jfd, pPager->journalOff, cksum);
+ pPager->journalOff += 4;
+ }
+ IOTRACE(("JOUT %p %d %lld %d\n", pPager, pPg->pgno,
+ pPager->journalOff, pPager->pageSize));
+ PAGER_INCR(sqlite3_pager_writej_count);
+ PAGERTRACE5("JOURNAL %d page %d needSync=%d hash(%08x)\n",
+ PAGERID(pPager), pPg->pgno, pPg->needSync, pager_pagehash(pPg));
+
+ /* An error has occured writing to the journal file. The
+ ** transaction will be rolled back by the layer above.
+ */
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+
+ pPager->nRec++;
+ assert( pPager->pInJournal!=0 );
+ sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);
+ pPg->needSync = !pPager->noSync;
+ if( pPager->stmtInUse ){
+ sqlite3BitvecSet(pPager->pInStmt, pPg->pgno);
+ }
+ }
+ }else{
+ pPg->needSync = !pPager->journalStarted && !pPager->noSync;
+ PAGERTRACE4("APPEND %d page %d needSync=%d\n",
+ PAGERID(pPager), pPg->pgno, pPg->needSync);
+ }
+ if( pPg->needSync ){
+ pPager->needSync = 1;
+ }
+ pPg->inJournal = 1;
+ }
+
+ /* If the statement journal is open and the page is not in it,
+ ** then write the current page to the statement journal. Note that
+ ** the statement journal format differs from the standard journal format
+ ** in that it omits the checksums and the header.
+ */
+ if( pPager->stmtInUse
+ && !pageInStatement(pPg)
+ && (int)pPg->pgno<=pPager->stmtSize
+ ){
+ assert( pPg->inJournal || (int)pPg->pgno>pPager->origDbSize );
+ if( MEMDB ){
+ PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager);
+ assert( pHist->pStmt==0 );
+ pHist->pStmt = sqlite3PageMalloc( pPager->pageSize );
+ if( pHist->pStmt ){
+ memcpy(pHist->pStmt, PGHDR_TO_DATA(pPg), pPager->pageSize);
+ }
+ PAGERTRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
+ page_add_to_stmt_list(pPg);
+ }else{
+ i64 offset = pPager->stmtNRec*(4+pPager->pageSize);
+ char *pData2 = CODEC2(pPager, pData, pPg->pgno, 7);
+ rc = write32bits(pPager->stfd, offset, pPg->pgno);
+ if( rc==SQLITE_OK ){
+ rc = sqlite3OsWrite(pPager->stfd, pData2, pPager->pageSize, offset+4);
+ }
+ PAGERTRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ pPager->stmtNRec++;
+ assert( pPager->pInStmt!=0 );
+ sqlite3BitvecSet(pPager->pInStmt, pPg->pgno);
+ }
+ }
+ }
+
+ /* Update the database size and return.
+ */
+ assert( pPager->state>=PAGER_SHARED );
+ if( pPager->dbSize<(int)pPg->pgno ){
+ pPager->dbSize = pPg->pgno;
+ if( !MEMDB && pPager->dbSize==PENDING_BYTE/pPager->pageSize ){
+ pPager->dbSize++;
+ }
+ }
+ return rc;
+}
+
+/*
+** This function is used to mark a data-page as writable. It uses
+** pager_write() to open a journal file (if it is not already open)
+** and write the page *pData to the journal.
+**
+** The difference between this function and pager_write() is that this
+** function also deals with the special case where 2 or more pages
+** fit on a single disk sector. In this case all co-resident pages
+** must have been written to the journal file before returning.
+*/
+int sqlite3PagerWrite(DbPage *pDbPage){
+ int rc = SQLITE_OK;
+
+ PgHdr *pPg = pDbPage;
+ Pager *pPager = pPg->pPager;
+ Pgno nPagePerSector = (pPager->sectorSize/pPager->pageSize);
+
+ pagerEnter(pPager);
+ if( !MEMDB && nPagePerSector>1 ){
+ Pgno nPageCount; /* Total number of pages in database file */
+ Pgno pg1; /* First page of the sector pPg is located on. */
+ int nPage; /* Number of pages starting at pg1 to journal */
+ int ii;
+ int needSync = 0;
+
+ /* Set the doNotSync flag to 1. This is because we cannot allow a journal
+ ** header to be written between the pages journaled by this function.
+ */
+ assert( pPager->doNotSync==0 );
+ pPager->doNotSync = 1;
+
+ /* This trick assumes that both the page-size and sector-size are
+ ** an integer power of 2. It sets variable pg1 to the identifier
+ ** of the first page of the sector pPg is located on.
+ */
+ pg1 = ((pPg->pgno-1) & ~(nPagePerSector-1)) + 1;
+
+ sqlite3PagerPagecount(pPager, (int *)&nPageCount);
+ if( pPg->pgno>nPageCount ){
+ nPage = (pPg->pgno - pg1)+1;
+ }else if( (pg1+nPagePerSector-1)>nPageCount ){
+ nPage = nPageCount+1-pg1;
+ }else{
+ nPage = nPagePerSector;
+ }
+ assert(nPage>0);
+ assert(pg1<=pPg->pgno);
+ assert((pg1+nPage)>pPg->pgno);
+
+ for(ii=0; ii<nPage && rc==SQLITE_OK; ii++){
+ Pgno pg = pg1+ii;
+ PgHdr *pPage;
+ if( pg==pPg->pgno || !sqlite3BitvecTest(pPager->pInJournal, pg) ){
+ if( pg!=PAGER_MJ_PGNO(pPager) ){
+ rc = sqlite3PagerGet(pPager, pg, &pPage);
+ if( rc==SQLITE_OK ){
+ rc = pager_write(pPage);
+ if( pPage->needSync ){
+ needSync = 1;
+ }
+ sqlite3PagerUnref(pPage);
+ }
+ }
+ }else if( (pPage = pager_lookup(pPager, pg))!=0 ){
+ if( pPage->needSync ){
+ needSync = 1;
+ }
+ }
+ }
+
+ /* If the PgHdr.needSync flag is set for any of the nPage pages
+ ** starting at pg1, then it needs to be set for all of them. Because
+ ** writing to any of these nPage pages may damage the others, the
+ ** journal file must contain sync()ed copies of all of them
+ ** before any of them can be written out to the database file.
+ */
+ if( needSync ){
+ for(ii=0; ii<nPage && needSync; ii++){
+ PgHdr *pPage = pager_lookup(pPager, pg1+ii);
+ if( pPage ) pPage->needSync = 1;
+ }
+ assert(pPager->needSync);
+ }
+
+ assert( pPager->doNotSync==1 );
+ pPager->doNotSync = 0;
+ }else{
+ rc = pager_write(pDbPage);
+ }
+ pagerLeave(pPager);
+ return rc;
+}
+
+/*
+** Return TRUE if the page given in the argument was previously passed
+** to sqlite3PagerWrite(). In other words, return TRUE if it is ok
+** to change the content of the page.
+*/
+#ifndef NDEBUG
+int sqlite3PagerIswriteable(DbPage *pPg){
+ return pPg->dirty;
+}
+#endif
+
+/*
+** A call to this routine tells the pager that it is not necessary to
+** write the information on page pPg back to the disk, even though
+** that page might be marked as dirty.
+**
+** The overlying software layer calls this routine when all of the data
+** on the given page is unused. The pager marks the page as clean so
+** that it does not get written to disk.
+**
+** Tests show that this optimization, together with the
+** sqlite3PagerDontRollback() below, more than double the speed
+** of large INSERT operations and quadruple the speed of large DELETEs.
+**
+** When this routine is called, set the alwaysRollback flag to true.
+** Subsequent calls to sqlite3PagerDontRollback() for the same page
+** will thereafter be ignored. This is necessary to avoid a problem
+** where a page with data is added to the freelist during one part of
+** a transaction then removed from the freelist during a later part
+** of the same transaction and reused for some other purpose. When it
+** is first added to the freelist, this routine is called. When reused,
+** the sqlite3PagerDontRollback() routine is called. But because the
+** page contains critical data, we still need to be sure it gets
+** rolled back in spite of the sqlite3PagerDontRollback() call.
+*/
+void sqlite3PagerDontWrite(DbPage *pDbPage){
+ PgHdr *pPg = pDbPage;
+ Pager *pPager = pPg->pPager;
+
+ if( MEMDB ) return;
+ pagerEnter(pPager);
+ pPg->alwaysRollback = 1;
+ if( pPg->dirty && !pPager->stmtInUse ){
+ assert( pPager->state>=PAGER_SHARED );
+ if( pPager->dbSize==(int)pPg->pgno && pPager->origDbSize<pPager->dbSize ){
+ /* If this pages is the last page in the file and the file has grown
+ ** during the current transaction, then do NOT mark the page as clean.
+ ** When the database file grows, we must make sure that the last page
+ ** gets written at least once so that the disk file will be the correct
+ ** size. If you do not write this page and the size of the file
+ ** on the disk ends up being too small, that can lead to database
+ ** corruption during the next transaction.
+ */
+ }else{
+ PAGERTRACE3("DONT_WRITE page %d of %d\n", pPg->pgno, PAGERID(pPager));
+ IOTRACE(("CLEAN %p %d\n", pPager, pPg->pgno))
+ makeClean(pPg);
+#ifdef SQLITE_CHECK_PAGES
+ pPg->pageHash = pager_pagehash(pPg);
+#endif
+ }
+ }
+ pagerLeave(pPager);
+}
+
+/*
+** A call to this routine tells the pager that if a rollback occurs,
+** it is not necessary to restore the data on the given page. This
+** means that the pager does not have to record the given page in the
+** rollback journal.
+**
+** If we have not yet actually read the content of this page (if
+** the PgHdr.needRead flag is set) then this routine acts as a promise
+** that we will never need to read the page content in the future.
+** so the needRead flag can be cleared at this point.
+*/
+void sqlite3PagerDontRollback(DbPage *pPg){
+ Pager *pPager = pPg->pPager;
+
+ pagerEnter(pPager);
+ assert( pPager->state>=PAGER_RESERVED );
+
+ /* If the journal file is not open, or DontWrite() has been called on
+ ** this page (DontWrite() sets the alwaysRollback flag), then this
+ ** function is a no-op.
+ */
+ if( pPager->journalOpen==0 || pPg->alwaysRollback || pPager->alwaysRollback ){
+ pagerLeave(pPager);
+ return;
+ }
+ assert( !MEMDB ); /* For a memdb, pPager->journalOpen is always 0 */
+
+#ifdef SQLITE_SECURE_DELETE
+ if( pPg->inJournal || (int)pPg->pgno > pPager->origDbSize ){
+ return;
+ }
+#endif
+
+ /* If SECURE_DELETE is disabled, then there is no way that this
+ ** routine can be called on a page for which sqlite3PagerDontWrite()
+ ** has not been previously called during the same transaction.
+ ** And if DontWrite() has previously been called, the following
+ ** conditions must be met.
+ **
+ ** (Later:) Not true. If the database is corrupted by having duplicate
+ ** pages on the freelist (ex: corrupt9.test) then the following is not
+ ** necessarily true:
+ */
+ /* assert( !pPg->inJournal && (int)pPg->pgno <= pPager->origDbSize ); */
+
+ assert( pPager->pInJournal!=0 );
+ sqlite3BitvecSet(pPager->pInJournal, pPg->pgno);
+ pPg->inJournal = 1;
+ pPg->needRead = 0;
+ if( pPager->stmtInUse ){
+ assert( pPager->stmtSize >= pPager->origDbSize );
+ sqlite3BitvecSet(pPager->pInStmt, pPg->pgno);
+ }
+ PAGERTRACE3("DONT_ROLLBACK page %d of %d\n", pPg->pgno, PAGERID(pPager));
+ IOTRACE(("GARBAGE %p %d\n", pPager, pPg->pgno))
+ pagerLeave(pPager);
+}
+
+
+/*
+** This routine is called to increment the database file change-counter,
+** stored at byte 24 of the pager file.
+*/
+static int pager_incr_changecounter(Pager *pPager, int isDirect){
+ PgHdr *pPgHdr;
+ u32 change_counter;
+ int rc = SQLITE_OK;
+
+#ifndef SQLITE_ENABLE_ATOMIC_WRITE
+ assert( isDirect==0 ); /* isDirect is only true for atomic writes */
+#endif
+ if( !pPager->changeCountDone ){
+ /* Open page 1 of the file for writing. */
+ rc = sqlite3PagerGet(pPager, 1, &pPgHdr);
+ if( rc!=SQLITE_OK ) return rc;
+
+ if( !isDirect ){
+ rc = sqlite3PagerWrite(pPgHdr);
+ if( rc!=SQLITE_OK ){
+ sqlite3PagerUnref(pPgHdr);
+ return rc;
+ }
+ }
+
+ /* Increment the value just read and write it back to byte 24. */
+ change_counter = sqlite3Get4byte((u8*)pPager->dbFileVers);
+ change_counter++;
+ put32bits(((char*)PGHDR_TO_DATA(pPgHdr))+24, change_counter);
+
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+ if( isDirect && pPager->fd->pMethods ){
+ const void *zBuf = PGHDR_TO_DATA(pPgHdr);
+ rc = sqlite3OsWrite(pPager->fd, zBuf, pPager->pageSize, 0);
+ }
+#endif
+
+ /* Release the page reference. */
+ sqlite3PagerUnref(pPgHdr);
+ pPager->changeCountDone = 1;
+ }
+ return rc;
+}
+
+/*
+** Sync the pager file to disk.
+*/
+int sqlite3PagerSync(Pager *pPager){
+ int rc;
+ pagerEnter(pPager);
+ rc = sqlite3OsSync(pPager->fd, pPager->sync_flags);
+ pagerLeave(pPager);
+ return rc;
+}
+
+/*
+** Sync the database file for the pager pPager. zMaster points to the name
+** of a master journal file that should be written into the individual
+** journal file. zMaster may be NULL, which is interpreted as no master
+** journal (a single database transaction).
+**
+** This routine ensures that the journal is synced, all dirty pages written
+** to the database file and the database file synced. The only thing that
+** remains to commit the transaction is to delete the journal file (or
+** master journal file if specified).
+**
+** Note that if zMaster==NULL, this does not overwrite a previous value
+** passed to an sqlite3PagerCommitPhaseOne() call.
+**
+** If parameter nTrunc is non-zero, then the pager file is truncated to
+** nTrunc pages (this is used by auto-vacuum databases).
+**
+** If the final parameter - noSync - is true, then the database file itself
+** is not synced. The caller must call sqlite3PagerSync() directly to
+** sync the database file before calling CommitPhaseTwo() to delete the
+** journal file in this case.
+*/
+int sqlite3PagerCommitPhaseOne(
+ Pager *pPager,
+ const char *zMaster,
+ Pgno nTrunc,
+ int noSync
+){
+ int rc = SQLITE_OK;
+
+ if( pPager->errCode ){
+ return pPager->errCode;
+ }
+
+ /* If no changes have been made, we can leave the transaction early.
+ */
+ if( pPager->dbModified==0 &&
+ (pPager->journalMode!=PAGER_JOURNALMODE_DELETE ||
+ pPager->exclusiveMode!=0) ){
+ assert( pPager->dirtyCache==0 || pPager->journalOpen==0 );
+ return SQLITE_OK;
+ }
+
+ PAGERTRACE4("DATABASE SYNC: File=%s zMaster=%s nTrunc=%d\n",
+ pPager->zFilename, zMaster, nTrunc);
+ pagerEnter(pPager);
+
+ /* If this is an in-memory db, or no pages have been written to, or this
+ ** function has already been called, it is a no-op.
+ */
+ if( pPager->state!=PAGER_SYNCED && !MEMDB && pPager->dirtyCache ){
+ PgHdr *pPg;
+
+#ifdef SQLITE_ENABLE_ATOMIC_WRITE
+ /* The atomic-write optimization can be used if all of the
+ ** following are true:
+ **
+ ** + The file-system supports the atomic-write property for
+ ** blocks of size page-size, and
+ ** + This commit is not part of a multi-file transaction, and
+ ** + Exactly one page has been modified and store in the journal file.
+ **
+ ** If the optimization can be used, then the journal file will never
+ ** be created for this transaction.
+ */
+ int useAtomicWrite = (
+ !zMaster &&
+ pPager->journalOpen &&
+ pPager->journalOff==jrnlBufferSize(pPager) &&
+ nTrunc==0 &&
+ (0==pPager->pDirty || 0==pPager->pDirty->pDirty)
+ );
+ assert( pPager->journalOpen || pPager->journalMode==PAGER_JOURNALMODE_OFF );
+ if( useAtomicWrite ){
+ /* Update the nRec field in the journal file. */
+ int offset = pPager->journalHdr + sizeof(aJournalMagic);
+ assert(pPager->nRec==1);
+ rc = write32bits(pPager->jfd, offset, pPager->nRec);
+
+ /* Update the db file change counter. The following call will modify
+ ** the in-memory representation of page 1 to include the updated
+ ** change counter and then write page 1 directly to the database
+ ** file. Because of the atomic-write property of the host file-system,
+ ** this is safe.
+ */
+ if( rc==SQLITE_OK ){
+ rc = pager_incr_changecounter(pPager, 1);
+ }
+ }else{
+ rc = sqlite3JournalCreate(pPager->jfd);
+ }
+
+ if( !useAtomicWrite && rc==SQLITE_OK )
+#endif
+
+ /* If a master journal file name has already been written to the
+ ** journal file, then no sync is required. This happens when it is
+ ** written, then the process fails to upgrade from a RESERVED to an
+ ** EXCLUSIVE lock. The next time the process tries to commit the
+ ** transaction the m-j name will have already been written.
+ */
+ if( !pPager->setMaster ){
+ rc = pager_incr_changecounter(pPager, 0);
+ if( rc!=SQLITE_OK ) goto sync_exit;
+ if( pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( nTrunc!=0 ){
+ /* If this transaction has made the database smaller, then all pages
+ ** being discarded by the truncation must be written to the journal
+ ** file.
+ */
+ Pgno i;
+ int iSkip = PAGER_MJ_PGNO(pPager);
+ for( i=nTrunc+1; i<=pPager->origDbSize; i++ ){
+ if( !sqlite3BitvecTest(pPager->pInJournal, i) && i!=iSkip ){
+ rc = sqlite3PagerGet(pPager, i, &pPg);
+ if( rc!=SQLITE_OK ) goto sync_exit;
+ rc = sqlite3PagerWrite(pPg);
+ sqlite3PagerUnref(pPg);
+ if( rc!=SQLITE_OK ) goto sync_exit;
+ }
+ }
+ }
+#endif
+ rc = writeMasterJournal(pPager, zMaster);
+ if( rc!=SQLITE_OK ) goto sync_exit;
+ rc = syncJournal(pPager);
+ }
+ }
+ if( rc!=SQLITE_OK ) goto sync_exit;
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+ if( nTrunc!=0 ){
+ rc = sqlite3PagerTruncate(pPager, nTrunc);
+ if( rc!=SQLITE_OK ) goto sync_exit;
+ }
+#endif
+
+ /* Write all dirty pages to the database file */
+ pPg = pager_get_all_dirty_pages(pPager);
+ rc = pager_write_pagelist(pPg);
+ if( rc!=SQLITE_OK ){
+ assert( rc!=SQLITE_IOERR_BLOCKED );
+ /* The error might have left the dirty list all fouled up here,
+ ** but that does not matter because if the if the dirty list did
+ ** get corrupted, then the transaction will roll back and
+ ** discard the dirty list. There is an assert in
+ ** pager_get_all_dirty_pages() that verifies that no attempt
+ ** is made to use an invalid dirty list.
+ */
+ goto sync_exit;
+ }
+ pPager->pDirty = 0;
+
+ /* Sync the database file. */
+ if( !pPager->noSync && !noSync ){
+ rc = sqlite3OsSync(pPager->fd, pPager->sync_flags);
+ }
+ IOTRACE(("DBSYNC %p\n", pPager))
+
+ pPager->state = PAGER_SYNCED;
+ }else if( MEMDB && nTrunc!=0 ){
+ rc = sqlite3PagerTruncate(pPager, nTrunc);
+ }
+
+sync_exit:
+ if( rc==SQLITE_IOERR_BLOCKED ){
+ /* pager_incr_changecounter() may attempt to obtain an exclusive
+ * lock to spill the cache and return IOERR_BLOCKED. But since
+ * there is no chance the cache is inconsistent, it is
+ * better to return SQLITE_BUSY.
+ */
+ rc = SQLITE_BUSY;
+ }
+ pagerLeave(pPager);
+ return rc;
+}
+
+
+/*
+** Commit all changes to the database and release the write lock.
+**
+** If the commit fails for any reason, a rollback attempt is made
+** and an error code is returned. If the commit worked, SQLITE_OK
+** is returned.
+*/
+int sqlite3PagerCommitPhaseTwo(Pager *pPager){
+ int rc;
+ PgHdr *pPg;
+
+ if( pPager->errCode ){
+ return pPager->errCode;
+ }
+ if( pPager->state<PAGER_RESERVED ){
+ return SQLITE_ERROR;
+ }
+ if( pPager->dbModified==0 &&
+ (pPager->journalMode!=PAGER_JOURNALMODE_DELETE ||
+ pPager->exclusiveMode!=0) ){
+ assert( pPager->dirtyCache==0 || pPager->journalOpen==0 );
+ return SQLITE_OK;
+ }
+ pagerEnter(pPager);
+ PAGERTRACE2("COMMIT %d\n", PAGERID(pPager));
+ if( MEMDB ){
+ pPg = pager_get_all_dirty_pages(pPager);
+ while( pPg ){
+ PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager);
+ clearHistory(pHist);
+ pPg->dirty = 0;
+ pPg->inJournal = 0;
+ pHist->inStmt = 0;
+ pPg->needSync = 0;
+ pHist->pPrevStmt = pHist->pNextStmt = 0;
+ pPg = pPg->pDirty;
+ }
+ pPager->pDirty = 0;
+#ifndef NDEBUG
+ for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
+ PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager);
+ assert( !pPg->alwaysRollback );
+ assert( !pHist->pOrig );
+ assert( !pHist->pStmt );
+ }
+#endif
+ pPager->pStmt = 0;
+ pPager->state = PAGER_SHARED;
+ pagerLeave(pPager);
+ return SQLITE_OK;
+ }
+ assert( pPager->state==PAGER_SYNCED || !pPager->dirtyCache );
+ rc = pager_end_transaction(pPager, pPager->setMaster);
+ rc = pager_error(pPager, rc);
+ pagerLeave(pPager);
+ return rc;
+}
+
+/*
+** Rollback all changes. The database falls back to PAGER_SHARED mode.
+** All in-memory cache pages revert to their original data contents.
+** The journal is deleted.
+**
+** This routine cannot fail unless some other process is not following
+** the correct locking protocol or unless some other
+** process is writing trash into the journal file (SQLITE_CORRUPT) or
+** unless a prior malloc() failed (SQLITE_NOMEM). Appropriate error
+** codes are returned for all these occasions. Otherwise,
+** SQLITE_OK is returned.
+*/
+int sqlite3PagerRollback(Pager *pPager){
+ int rc;
+ PAGERTRACE2("ROLLBACK %d\n", PAGERID(pPager));
+ if( MEMDB ){
+ PgHdr *p;
+ for(p=pPager->pAll; p; p=p->pNextAll){
+ PgHistory *pHist;
+ assert( !p->alwaysRollback );
+ if( !p->dirty ){
+ assert( !((PgHistory *)PGHDR_TO_HIST(p, pPager))->pOrig );
+ assert( !((PgHistory *)PGHDR_TO_HIST(p, pPager))->pStmt );
+ continue;
+ }
+
+ pHist = PGHDR_TO_HIST(p, pPager);
+ if( pHist->pOrig ){
+ memcpy(PGHDR_TO_DATA(p), pHist->pOrig, pPager->pageSize);
+ PAGERTRACE3("ROLLBACK-PAGE %d of %d\n", p->pgno, PAGERID(pPager));
+ }else{
+ PAGERTRACE3("PAGE %d is clean on %d\n", p->pgno, PAGERID(pPager));
+ }
+ clearHistory(pHist);
+ p->dirty = 0;
+ p->inJournal = 0;
+ pHist->inStmt = 0;
+ pHist->pPrevStmt = pHist->pNextStmt = 0;
+ if( pPager->xReiniter ){
+ pPager->xReiniter(p, pPager->pageSize);
+ }
+ }
+ pPager->pDirty = 0;
+ pPager->pStmt = 0;
+ pPager->dbSize = pPager->origDbSize;
+ pager_truncate_cache(pPager);
+ pPager->stmtInUse = 0;
+ pPager->state = PAGER_SHARED;
+ return SQLITE_OK;
+ }
+
+ pagerEnter(pPager);
+ if( !pPager->dirtyCache || !pPager->journalOpen ){
+ rc = pager_end_transaction(pPager, pPager->setMaster);
+ pagerLeave(pPager);
+ return rc;
+ }
+
+ if( pPager->errCode && pPager->errCode!=SQLITE_FULL ){
+ if( pPager->state>=PAGER_EXCLUSIVE ){
+ pager_playback(pPager, 0);
+ }
+ pagerLeave(pPager);
+ return pPager->errCode;
+ }
+ if( pPager->state==PAGER_RESERVED ){
+ int rc2;
+ rc = pager_playback(pPager, 0);
+ rc2 = pager_end_transaction(pPager, pPager->setMaster);
+ if( rc==SQLITE_OK ){
+ rc = rc2;
+ }
+ }else{
+ rc = pager_playback(pPager, 0);
+ }
+ /* pager_reset(pPager); */
+ pPager->dbSize = -1;
+
+ /* If an error occurs during a ROLLBACK, we can no longer trust the pager
+ ** cache. So call pager_error() on the way out to make any error
+ ** persistent.
+ */
+ rc = pager_error(pPager, rc);
+ pagerLeave(pPager);
+ return rc;
+}
+
+/*
+** Return TRUE if the database file is opened read-only. Return FALSE
+** if the database is (in theory) writable.
+*/
+int sqlite3PagerIsreadonly(Pager *pPager){
+ return pPager->readOnly;
+}
+
+/*
+** Return the number of references to the pager.
+*/
+int sqlite3PagerRefcount(Pager *pPager){
+ return pPager->nRef;
+}
+
+#ifdef SQLITE_TEST
+/*
+** This routine is used for testing and analysis only.
+*/
+int *sqlite3PagerStats(Pager *pPager){
+ static int a[11];
+ a[0] = pPager->nRef;
+ a[1] = pPager->nPage;
+ a[2] = pPager->mxPage;
+ a[3] = pPager->dbSize;
+ a[4] = pPager->state;
+ a[5] = pPager->errCode;
+ a[6] = pPager->nHit;
+ a[7] = pPager->nMiss;
+ a[8] = 0; /* Used to be pPager->nOvfl */
+ a[9] = pPager->nRead;
+ a[10] = pPager->nWrite;
+ return a;
+}
+int sqlite3PagerIsMemdb(Pager *pPager){
+ return MEMDB;
+}
+#endif
+
+/*
+** Set the statement rollback point.
+**
+** This routine should be called with the transaction journal already
+** open. A new statement journal is created that can be used to rollback
+** changes of a single SQL command within a larger transaction.
+*/
+static int pagerStmtBegin(Pager *pPager){
+ int rc;
+ assert( !pPager->stmtInUse );
+ assert( pPager->state>=PAGER_SHARED );
+ assert( pPager->dbSize>=0 );
+ PAGERTRACE2("STMT-BEGIN %d\n", PAGERID(pPager));
+ if( MEMDB ){
+ pPager->stmtInUse = 1;
+ pPager->stmtSize = pPager->dbSize;
+ return SQLITE_OK;
+ }
+ if( !pPager->journalOpen ){
+ pPager->stmtAutoopen = 1;
+ return SQLITE_OK;
+ }
+ assert( pPager->journalOpen );
+ pagerLeave(pPager);
+ assert( pPager->pInStmt==0 );
+ pPager->pInStmt = sqlite3BitvecCreate(pPager->dbSize);
+ pagerEnter(pPager);
+ if( pPager->pInStmt==0 ){
+ /* sqlite3OsLock(pPager->fd, SHARED_LOCK); */
+ return SQLITE_NOMEM;
+ }
+ pPager->stmtJSize = pPager->journalOff;
+ pPager->stmtSize = pPager->dbSize;
+ pPager->stmtHdrOff = 0;
+ pPager->stmtCksum = pPager->cksumInit;
+ if( !pPager->stmtOpen ){
+ rc = sqlite3PagerOpentemp(pPager, pPager->stfd, SQLITE_OPEN_SUBJOURNAL);
+ if( rc ){
+ goto stmt_begin_failed;
+ }
+ pPager->stmtOpen = 1;
+ pPager->stmtNRec = 0;
+ }
+ pPager->stmtInUse = 1;
+ return SQLITE_OK;
+
+stmt_begin_failed:
+ if( pPager->pInStmt ){
+ sqlite3BitvecDestroy(pPager->pInStmt);
+ pPager->pInStmt = 0;
+ }
+ return rc;
+}
+int sqlite3PagerStmtBegin(Pager *pPager){
+ int rc;
+ pagerEnter(pPager);
+ rc = pagerStmtBegin(pPager);
+ pagerLeave(pPager);
+ return rc;
+}
+
+/*
+** Commit a statement.
+*/
+int sqlite3PagerStmtCommit(Pager *pPager){
+ pagerEnter(pPager);
+ if( pPager->stmtInUse ){
+ PgHdr *pPg, *pNext;
+ PAGERTRACE2("STMT-COMMIT %d\n", PAGERID(pPager));
+ if( !MEMDB ){
+ /* sqlite3OsTruncate(pPager->stfd, 0); */
+ sqlite3BitvecDestroy(pPager->pInStmt);
+ pPager->pInStmt = 0;
+ }else{
+ for(pPg=pPager->pStmt; pPg; pPg=pNext){
+ PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager);
+ pNext = pHist->pNextStmt;
+ assert( pHist->inStmt );
+ pHist->inStmt = 0;
+ pHist->pPrevStmt = pHist->pNextStmt = 0;
+ sqlite3PageFree(pHist->pStmt);
+ pHist->pStmt = 0;
+ }
+ }
+ pPager->stmtNRec = 0;
+ pPager->stmtInUse = 0;
+ pPager->pStmt = 0;
+ }
+ pPager->stmtAutoopen = 0;
+ pagerLeave(pPager);
+ return SQLITE_OK;
+}
+
+/*
+** Rollback a statement.
+*/
+int sqlite3PagerStmtRollback(Pager *pPager){
+ int rc;
+ pagerEnter(pPager);
+ if( pPager->stmtInUse ){
+ PAGERTRACE2("STMT-ROLLBACK %d\n", PAGERID(pPager));
+ if( MEMDB ){
+ PgHdr *pPg;
+ PgHistory *pHist;
+ for(pPg=pPager->pStmt; pPg; pPg=pHist->pNextStmt){
+ pHist = PGHDR_TO_HIST(pPg, pPager);
+ if( pHist->pStmt ){
+ memcpy(PGHDR_TO_DATA(pPg), pHist->pStmt, pPager->pageSize);
+ sqlite3PageFree(pHist->pStmt);
+ pHist->pStmt = 0;
+ }
+ }
+ pPager->dbSize = pPager->stmtSize;
+ pager_truncate_cache(pPager);
+ rc = SQLITE_OK;
+ }else{
+ rc = pager_stmt_playback(pPager);
+ }
+ sqlite3PagerStmtCommit(pPager);
+ }else{
+ rc = SQLITE_OK;
+ }
+ pPager->stmtAutoopen = 0;
+ pagerLeave(pPager);
+ return rc;
+}
+
+/*
+** Return the full pathname of the database file.
+*/
+const char *sqlite3PagerFilename(Pager *pPager){
+ return pPager->zFilename;
+}
+
+/*
+** Return the VFS structure for the pager.
+*/
+const sqlite3_vfs *sqlite3PagerVfs(Pager *pPager){
+ return pPager->pVfs;
+}
+
+/*
+** Return the file handle for the database file associated
+** with the pager. This might return NULL if the file has
+** not yet been opened.
+*/
+sqlite3_file *sqlite3PagerFile(Pager *pPager){
+ return pPager->fd;
+}
+
+/*
+** Return the directory of the database file.
+*/
+const char *sqlite3PagerDirname(Pager *pPager){
+ return pPager->zDirectory;
+}
+
+/*
+** Return the full pathname of the journal file.
+*/
+const char *sqlite3PagerJournalname(Pager *pPager){
+ return pPager->zJournal;
+}
+
+/*
+** Return true if fsync() calls are disabled for this pager. Return FALSE
+** if fsync()s are executed normally.
+*/
+int sqlite3PagerNosync(Pager *pPager){
+ return pPager->noSync;
+}
+
+#ifdef SQLITE_HAS_CODEC
+/*
+** Set the codec for this pager
+*/
+void sqlite3PagerSetCodec(
+ Pager *pPager,
+ void *(*xCodec)(void*,void*,Pgno,int),
+ void *pCodecArg
+){
+ pPager->xCodec = xCodec;
+ pPager->pCodecArg = pCodecArg;
+}
+#endif
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+/*
+** Move the page pPg to location pgno in the file.
+**
+** There must be no references to the page previously located at
+** pgno (which we call pPgOld) though that page is allowed to be
+** in cache. If the page previous located at pgno is not already
+** in the rollback journal, it is not put there by by this routine.
+**
+** References to the page pPg remain valid. Updating any
+** meta-data associated with pPg (i.e. data stored in the nExtra bytes
+** allocated along with the page) is the responsibility of the caller.
+**
+** A transaction must be active when this routine is called. It used to be
+** required that a statement transaction was not active, but this restriction
+** has been removed (CREATE INDEX needs to move a page when a statement
+** transaction is active).
+**
+** If the fourth argument, isCommit, is non-zero, then this page is being
+** moved as part of a database reorganization just before the transaction
+** is being committed. In this case, it is guaranteed that the database page
+** pPg refers to will not be written to again within this transaction.
+*/
+int sqlite3PagerMovepage(Pager *pPager, DbPage *pPg, Pgno pgno, int isCommit){
+ PgHdr *pPgOld; /* The page being overwritten. */
+ int h;
+ Pgno needSyncPgno = 0;
+
+ pagerEnter(pPager);
+ assert( pPg->nRef>0 );
+
+ PAGERTRACE5("MOVE %d page %d (needSync=%d) moves to %d\n",
+ PAGERID(pPager), pPg->pgno, pPg->needSync, pgno);
+ IOTRACE(("MOVE %p %d %d\n", pPager, pPg->pgno, pgno))
+
+ pager_get_content(pPg);
+
+ /* If the journal needs to be sync()ed before page pPg->pgno can
+ ** be written to, store pPg->pgno in local variable needSyncPgno.
+ **
+ ** If the isCommit flag is set, there is no need to remember that
+ ** the journal needs to be sync()ed before database page pPg->pgno
+ ** can be written to. The caller has already promised not to write to it.
+ */
+ if( pPg->needSync && !isCommit ){
+ needSyncPgno = pPg->pgno;
+ assert( pPg->inJournal || (int)pgno>pPager->origDbSize );
+ assert( pPg->dirty );
+ assert( pPager->needSync );
+ }
+
+ /* Unlink pPg from its hash-chain */
+ unlinkHashChain(pPager, pPg);
+
+ /* If the cache contains a page with page-number pgno, remove it
+ ** from its hash chain. Also, if the PgHdr.needSync was set for
+ ** page pgno before the 'move' operation, it needs to be retained
+ ** for the page moved there.
+ */
+ pPg->needSync = 0;
+ pPgOld = pager_lookup(pPager, pgno);
+ if( pPgOld ){
+ assert( pPgOld->nRef==0 );
+ unlinkHashChain(pPager, pPgOld);
+ makeClean(pPgOld);
+ pPg->needSync = pPgOld->needSync;
+ }else{
+ pPg->needSync = 0;
+ }
+ pPg->inJournal = sqlite3BitvecTest(pPager->pInJournal, pgno);
+
+ /* Change the page number for pPg and insert it into the new hash-chain. */
+ assert( pgno!=0 );
+ pPg->pgno = pgno;
+ h = pgno & (pPager->nHash-1);
+ if( pPager->aHash[h] ){
+ assert( pPager->aHash[h]->pPrevHash==0 );
+ pPager->aHash[h]->pPrevHash = pPg;
+ }
+ pPg->pNextHash = pPager->aHash[h];
+ pPager->aHash[h] = pPg;
+ pPg->pPrevHash = 0;
+
+ makeDirty(pPg);
+ pPager->dirtyCache = 1;
+ pPager->dbModified = 1;
+
+ if( needSyncPgno ){
+ /* If needSyncPgno is non-zero, then the journal file needs to be
+ ** sync()ed before any data is written to database file page needSyncPgno.
+ ** Currently, no such page exists in the page-cache and the
+ ** "is journaled" bitvec flag has been set. This needs to be remedied by
+ ** loading the page into the pager-cache and setting the PgHdr.needSync
+ ** flag.
+ **
+ ** If the attempt to load the page into the page-cache fails, (due
+ ** to a malloc() or IO failure), clear the bit in the pInJournal[]
+ ** array. Otherwise, if the page is loaded and written again in
+ ** this transaction, it may be written to the database file before
+ ** it is synced into the journal file. This way, it may end up in
+ ** the journal file twice, but that is not a problem.
+ **
+ ** The sqlite3PagerGet() call may cause the journal to sync. So make
+ ** sure the Pager.needSync flag is set too.
+ */
+ int rc;
+ PgHdr *pPgHdr;
+ assert( pPager->needSync );
+ rc = sqlite3PagerGet(pPager, needSyncPgno, &pPgHdr);
+ if( rc!=SQLITE_OK ){
+ if( pPager->pInJournal && (int)needSyncPgno<=pPager->origDbSize ){
+ sqlite3BitvecClear(pPager->pInJournal, needSyncPgno);
+ }
+ pagerLeave(pPager);
+ return rc;
+ }
+ pPager->needSync = 1;
+ pPgHdr->needSync = 1;
+ pPgHdr->inJournal = 1;
+ makeDirty(pPgHdr);
+ sqlite3PagerUnref(pPgHdr);
+ }
+
+ pagerLeave(pPager);
+ return SQLITE_OK;
+}
+#endif
+
+/*
+** Return a pointer to the data for the specified page.
+*/
+void *sqlite3PagerGetData(DbPage *pPg){
+ return PGHDR_TO_DATA(pPg);
+}
+
+/*
+** Return a pointer to the Pager.nExtra bytes of "extra" space
+** allocated along with the specified page.
+*/
+void *sqlite3PagerGetExtra(DbPage *pPg){
+ Pager *pPager = pPg->pPager;
+ return (pPager?PGHDR_TO_EXTRA(pPg, pPager):0);
+}
+
+/*
+** Get/set the locking-mode for this pager. Parameter eMode must be one
+** of PAGER_LOCKINGMODE_QUERY, PAGER_LOCKINGMODE_NORMAL or
+** PAGER_LOCKINGMODE_EXCLUSIVE. If the parameter is not _QUERY, then
+** the locking-mode is set to the value specified.
+**
+** The returned value is either PAGER_LOCKINGMODE_NORMAL or
+** PAGER_LOCKINGMODE_EXCLUSIVE, indicating the current (possibly updated)
+** locking-mode.
+*/
+int sqlite3PagerLockingMode(Pager *pPager, int eMode){
+ assert( eMode==PAGER_LOCKINGMODE_QUERY
+ || eMode==PAGER_LOCKINGMODE_NORMAL
+ || eMode==PAGER_LOCKINGMODE_EXCLUSIVE );
+ assert( PAGER_LOCKINGMODE_QUERY<0 );
+ assert( PAGER_LOCKINGMODE_NORMAL>=0 && PAGER_LOCKINGMODE_EXCLUSIVE>=0 );
+ if( eMode>=0 && !pPager->tempFile ){
+ pPager->exclusiveMode = eMode;
+ }
+ return (int)pPager->exclusiveMode;
+}
+
+/*
+** Get/set the journal-mode for this pager. Parameter eMode must be one
+** of PAGER_JOURNALMODE_QUERY, PAGER_JOURNALMODE_DELETE or
+** PAGER_JOURNALMODE_PERSIST. If the parameter is not _QUERY, then
+** the journal-mode is set to the value specified.
+**
+** The returned value is either PAGER_JOURNALMODE_DELETE or
+** PAGER_JOURNALMODE_PERSIST, indicating the current (possibly updated)
+** journal-mode.
+*/
+int sqlite3PagerJournalMode(Pager *pPager, int eMode){
+ assert( eMode==PAGER_JOURNALMODE_QUERY
+ || eMode==PAGER_JOURNALMODE_DELETE
+ || eMode==PAGER_JOURNALMODE_PERSIST
+ || eMode==PAGER_JOURNALMODE_OFF );
+ assert( PAGER_JOURNALMODE_QUERY<0 );
+ assert( PAGER_JOURNALMODE_DELETE>=0 && PAGER_JOURNALMODE_PERSIST>=0 );
+ if( eMode>=0 ){
+ pPager->journalMode = eMode;
+ }
+ return (int)pPager->journalMode;
+}
+
+/*
+** Get/set the size-limit used for persistent journal files.
+*/
+i64 sqlite3PagerJournalSizeLimit(Pager *pPager, i64 iLimit){
+ if( iLimit>=-1 ){
+ pPager->journalSizeLimit = iLimit;
+ }
+ return pPager->journalSizeLimit;
+}
+
+#endif /* SQLITE_OMIT_DISKIO */