--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/webengine/webkitutils/SqliteSymbian/pager.c Mon Mar 30 12:54:55 2009 +0300
@@ -0,0 +1,3933 @@
+/*
+** 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 1.271 2006/08/08 13:51:43 drh Exp $
+*/
+#ifndef SQLITE_OMIT_DISKIO
+#include "sqliteInt.h"
+#include "os.h"
+#include "pager.h"
+#include <assert.h>
+#include <string.h>
+
+/*
+** Macros for troubleshooting. Normally turned off
+*/
+#if 0
+#define TRACE1(X) sqlite3DebugPrintf(X)
+#define TRACE2(X,Y) sqlite3DebugPrintf(X,Y)
+#define TRACE3(X,Y,Z) sqlite3DebugPrintf(X,Y,Z)
+#define TRACE4(X,Y,Z,W) sqlite3DebugPrintf(X,Y,Z,W)
+#define TRACE5(X,Y,Z,W,V) sqlite3DebugPrintf(X,Y,Z,W,V)
+#else
+#define TRACE1(X)
+#define TRACE2(X,Y)
+#define TRACE3(X,Y,Z)
+#define TRACE4(X,Y,Z,W)
+#define TRACE5(X,Y,Z,W,V)
+#endif
+
+/*
+** The following two macros are used within the TRACEX() macros above
+** to print out file-descriptors.
+**
+** PAGERID() takes a pointer to a Pager struct as it's argument. The
+** associated file-descriptor is returned. FILEHANDLEID() takes an OsFile
+** struct as it's 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 the
+** journal file and the transaction will be
+** committed.
+**
+** The page cache comes up in PAGER_UNLOCK. The first time a
+** sqlite3pager_get() 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 sqlite3pager_write() is called, the state transitions to
+** PAGER_RESERVED. (Note that sqlite_page_write() can only be
+** called on an outstanding page which means that the pager must
+** be in PAGER_SHARED before it transitions to PAGER_RESERVED.)
+** The transition to PAGER_EXCLUSIVE occurs when before any changes
+** are made to the database file. After an sqlite3pager_rollback()
+** or sqlite_pager_commit(), the state goes back to PAGER_SHARED.
+*/
+#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)
+
+/*
+** 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 sqlite3pager_write() on a page prior to making
+** any modifications to that page. The first time sqlite3pager_write()
+** 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 sqlite3pager_write() is called and
+** is cleared again when the page content is written back to the original
+** database file.
+*/
+typedef struct PgHdr PgHdr;
+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 */
+ PgHdr *pNextFree, *pPrevFree; /* Freelist of pages where nRef==0 */
+ PgHdr *pNextAll; /* A list of all pages */
+ PgHdr *pNextStmt, *pPrevStmt; /* List of pages in the statement journal */
+ u8 inJournal; /* TRUE if has been written to journal */
+ u8 inStmt; /* TRUE if in the statement subjournal */
+ u8 dirty; /* TRUE if we need to write back changes */
+ u8 needSync; /* Sync journal before writing this page */
+ u8 alwaysRollback; /* Disable dont_rollback() for this page */
+ short int nRef; /* Number of users of this page */
+ PgHdr *pDirty, *pPrevDirty; /* Dirty pages */
+ u32 notUsed; /* Buffer space */
+#ifdef SQLITE_CHECK_PAGES
+ u32 pageHash;
+#endif
+ /* pPager->pageSize bytes of page data follow this header */
+ /* Pager.nExtra bytes of local data follow the page data */
+};
+
+/*
+** 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 */
+};
+
+/*
+** 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) ((void*)(&(P)[1]))
+#define DATA_TO_PGHDR(D) (&((PgHdr*)(D))[-1])
+#define PGHDR_TO_EXTRA(G,P) ((void*)&((char*)(&(G)[1]))[(P)->pageSize])
+#define PGHDR_TO_HIST(P,PGR) \
+ ((PgHistory*)&((char*)(&(P)[1]))[(PGR)->pageSize+(PGR)->nExtra])
+
+/*
+** A open page cache is an instance of the following structure.
+**
+** Pager.errCode may be set to SQLITE_IOERR, SQLITE_CORRUPT, SQLITE_PROTOCOL
+** 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 sqlite3pager_get() and sqlite3pager_lookup()
+** APIs, they may still be used successfully.
+*/
+struct Pager {
+ 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 full_fsync; /* Use F_FULLFSYNC when available */
+ u8 state; /* PAGER_UNLOCK, _SHARED, _RESERVED, etc. */
+ u8 errCode; /* One of several kinds of errors */
+ 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 dont_rollback() 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 */
+ 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 nMaxPage; /* High water mark of nPage */
+ int nRef; /* Number of in-memory pages with PgHdr.nRef>0 */
+ int mxPage; /* Maximum number of pages to hold in cache */
+ u8 *aInJournal; /* One bit for each page in the database file */
+ u8 *aInStmt; /* 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 */
+ OsFile *fd, *jfd; /* File descriptors for database and journal */
+ OsFile *stfd; /* File descriptor for the statement subjournal*/
+ BusyHandler *pBusyHandler; /* Pointer to sqlite.busyHandler */
+ PgHdr *pFirst, *pLast; /* List of free pages */
+ PgHdr *pFirstSynced; /* First free page with PgHdr.needSync==0 */
+ 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, nOvfl; /* Cache hits, missing, and LRU overflows */
+ int nRead,nWrite; /* Database pages read/written */
+#endif
+ void (*xDestructor)(void*,int); /* Call this routine when freeing pages */
+ void (*xReiniter)(void*,int); /* Call this routine when reloading pages */
+ void *(*xCodec)(void*,void*,Pgno,int); /* Routine for en/decoding data */
+ void *pCodecArg; /* First argument to xCodec() */
+ 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; /* Linked list of pagers in this thread */
+#endif
+};
+
+/*
+** If SQLITE_TEST is defined then increment the variable given in
+** the argument
+*/
+#ifdef SQLITE_TEST
+# define TEST_INCR(x) x++
+#else
+# define TEST_INCR(x)
+#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
+
+/*
+** The default size of a disk sector
+*/
+#define PAGER_SECTOR_SIZE 512
+
+/*
+** 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
+
+/*
+** Enable reference count tracking (for debugging) here:
+*/
+#ifdef SQLITE_TEST
+ int pager3_refinfo_enable = 0;
+ static void pager_refinfo(PgHdr *p){
+ static int cnt = 0;
+ if( !pager3_refinfo_enable ) return;
+ sqlite3DebugPrintf(
+ "REFCNT: %4d addr=%p nRef=%d\n",
+ p->pgno, PGHDR_TO_DATA(p), p->nRef
+ );
+ cnt++; /* Something to set a breakpoint on */
+ }
+# define REFINFO(X) pager_refinfo(X)
+#else
+# define REFINFO(X)
+#endif
+
+
+/*
+** 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 );
+ aHash = sqliteMalloc( sizeof(aHash[0])*N );
+ if( aHash==0 ){
+ /* Failure to rehash is not an error. It is only a performance hit. */
+ return;
+ }
+ sqliteFree(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(OsFile *fd, u32 *pRes){
+ unsigned char ac[4];
+ int rc = sqlite3OsRead(fd, ac, sizeof(ac));
+ if( rc==SQLITE_OK ){
+ *pRes = (ac[0]<<24) | (ac[1]<<16) | (ac[2]<<8) | ac[3];
+ }
+ return rc;
+}
+
+/*
+** Write a 32-bit integer into a string buffer in big-endian byte order.
+*/
+static void put32bits(char *ac, u32 val){
+ ac[0] = (val>>24) & 0xff;
+ ac[1] = (val>>16) & 0xff;
+ ac[2] = (val>>8) & 0xff;
+ ac[3] = val & 0xff;
+}
+
+/*
+** 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(OsFile *fd, u32 val){
+ char ac[4];
+ put32bits(ac, val);
+ return sqlite3OsWrite(fd, ac, 4);
+}
+
+/*
+** Read a 32-bit integer at offset 'offset' from the page identified by
+** page header 'p'.
+*/
+static u32 retrieve32bits(PgHdr *p, int offset){
+ unsigned char *ac;
+ ac = &((unsigned char*)PGHDR_TO_DATA(p))[offset];
+ return (ac[0]<<24) | (ac[1]<<16) | (ac[2]<<8) | ac[3];
+}
+
+
+/*
+** 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_PROTOCOL,
+** the error becomes persistent. All subsequent API calls on this Pager
+** will immediately return the same error code.
+*/
+static int pager_error(Pager *pPager, int rc){
+ assert( pPager->errCode==SQLITE_FULL || pPager->errCode==SQLITE_OK );
+ if(
+ rc==SQLITE_FULL ||
+ rc==SQLITE_IOERR ||
+ rc==SQLITE_CORRUPT ||
+ rc==SQLITE_PROTOCOL
+ ){
+ pPager->errCode = rc;
+ }
+ return rc;
+}
+
+#ifdef SQLITE_CHECK_PAGES
+/*
+** Return a 32-bit hash of the page data for pPage.
+*/
+static u32 pager_pagehash(PgHdr *pPage){
+ u32 hash = 0;
+ int i;
+ unsigned char *pData = (unsigned char *)PGHDR_TO_DATA(pPage);
+ for(i=0; i<pPage->pPager->pageSize; i++){
+ hash = (hash+i)^pData[i];
+ }
+ return hash;
+}
+
+/*
+** 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 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 obtained from sqliteMalloc(). *pzMaster is
+** set to point at the memory and SQLITE_OK returned. The caller must
+** sqliteFree() *pzMaster.
+**
+** If no master journal file name is present *pzMaster is set to 0 and
+** SQLITE_OK returned.
+*/
+static int readMasterJournal(OsFile *pJrnl, char **pzMaster){
+ int rc;
+ u32 len;
+ i64 szJ;
+ u32 cksum;
+ int i;
+ unsigned char aMagic[8]; /* A buffer to hold the magic header */
+
+ *pzMaster = 0;
+
+ rc = sqlite3OsFileSize(pJrnl, &szJ);
+ if( rc!=SQLITE_OK || szJ<16 ) return rc;
+
+ rc = sqlite3OsSeek(pJrnl, szJ-16);
+ if( rc!=SQLITE_OK ) return rc;
+
+ rc = read32bits(pJrnl, &len);
+ if( rc!=SQLITE_OK ) return rc;
+
+ rc = read32bits(pJrnl, &cksum);
+ if( rc!=SQLITE_OK ) return rc;
+
+ rc = sqlite3OsRead(pJrnl, aMagic, 8);
+ if( rc!=SQLITE_OK || memcmp(aMagic, aJournalMagic, 8) ) return rc;
+
+ rc = sqlite3OsSeek(pJrnl, szJ-16-len);
+ if( rc!=SQLITE_OK ) return rc;
+
+ *pzMaster = (char *)sqliteMalloc(len+1);
+ if( !*pzMaster ){
+ return SQLITE_NOMEM;
+ }
+ rc = sqlite3OsRead(pJrnl, *pzMaster, len);
+ if( rc!=SQLITE_OK ){
+ sqliteFree(*pzMaster);
+ *pzMaster = 0;
+ return rc;
+ }
+
+ /* See if the checksum matches the master journal name */
+ for(i=0; i<len; i++){
+ cksum -= (*pzMaster)[i];
+ }
+ 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.
+ */
+ sqliteFree(*pzMaster);
+ *pzMaster = 0;
+ }else{
+ (*pzMaster)[len] = '\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 int 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;
+ return sqlite3OsSeek(pPager->jfd, pPager->journalOff);
+}
+
+/*
+** 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.
+**
+** Followed by (JOURNAL_HDR_SZ - 24) bytes of unused space.
+*/
+static int writeJournalHdr(Pager *pPager){
+ char zHeader[sizeof(aJournalMagic)+16];
+
+ int rc = seekJournalHdr(pPager);
+ if( rc ) return rc;
+
+ pPager->journalHdr = pPager->journalOff;
+ if( pPager->stmtHdrOff==0 ){
+ pPager->stmtHdrOff = pPager->journalHdr;
+ }
+ pPager->journalOff += JOURNAL_HDR_SZ(pPager);
+
+ /* FIX ME:
+ **
+ ** Possibly for a pager not in no-sync mode, the journal magic should not
+ ** be written until nRec is filled in as part of next syncJournal().
+ **
+ ** Actually maybe the whole journal header should be delayed until that
+ ** point. Think about this.
+ */
+ memcpy(zHeader, aJournalMagic, sizeof(aJournalMagic));
+ /* The nRec Field. 0xFFFFFFFF for no-sync journals. */
+ put32bits(&zHeader[sizeof(aJournalMagic)], pPager->noSync ? 0xffffffff : 0);
+ /* The random check-hash initialiser */
+ sqlite3Randomness(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);
+ rc = sqlite3OsWrite(pPager->jfd, zHeader, sizeof(zHeader));
+
+ /* The journal header has been written successfully. Seek the journal
+ ** file descriptor to the end of the journal header sector.
+ */
+ if( rc==SQLITE_OK ){
+ rc = sqlite3OsSeek(pPager->jfd, pPager->journalOff-1);
+ if( rc==SQLITE_OK ){
+ rc = sqlite3OsWrite(pPager->jfd, "\000", 1);
+ }
+ }
+ 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 */
+
+ rc = seekJournalHdr(pPager);
+ if( rc ) return rc;
+
+ if( pPager->journalOff+JOURNAL_HDR_SZ(pPager) > journalSize ){
+ return SQLITE_DONE;
+ }
+
+ rc = sqlite3OsRead(pPager->jfd, aMagic, sizeof(aMagic));
+ if( rc ) return rc;
+
+ if( memcmp(aMagic, aJournalMagic, sizeof(aMagic))!=0 ){
+ return SQLITE_DONE;
+ }
+
+ rc = read32bits(pPager->jfd, pNRec);
+ if( rc ) return rc;
+
+ rc = read32bits(pPager->jfd, &pPager->cksumInit);
+ if( rc ) return rc;
+
+ rc = read32bits(pPager->jfd, pDbSize);
+ 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, (u32 *)&pPager->sectorSize);
+ if( rc ) return rc;
+
+ pPager->journalOff += JOURNAL_HDR_SZ(pPager);
+ rc = sqlite3OsSeek(pPager->jfd, pPager->journalOff);
+ return rc;
+}
+
+
+/*
+** 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;
+ 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 ){
+ rc = seekJournalHdr(pPager);
+ if( rc!=SQLITE_OK ) return rc;
+ }
+ pPager->journalOff += (len+20);
+
+ rc = write32bits(pPager->jfd, PAGER_MJ_PGNO(pPager));
+ if( rc!=SQLITE_OK ) return rc;
+
+ rc = sqlite3OsWrite(pPager->jfd, zMaster, len);
+ if( rc!=SQLITE_OK ) return rc;
+
+ put32bits(zBuf, len);
+ put32bits(&zBuf[4], cksum);
+ memcpy(&zBuf[8], aJournalMagic, sizeof(aJournalMagic));
+ rc = sqlite3OsWrite(pPager->jfd, zBuf, 8+sizeof(aJournalMagic));
+ pPager->needSync = !pPager->noSync;
+ 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 sqlite3pager_stmt_commit()
+** 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;
+ if( pPg->inStmt ) return;
+ assert( pPg->pPrevStmt==0 && pPg->pNextStmt==0 );
+ pPg->pPrevStmt = 0;
+ if( pPager->pStmt ){
+ pPager->pStmt->pPrevStmt = pPg;
+ }
+ pPg->pNextStmt = pPager->pStmt;
+ pPager->pStmt = pPg;
+ pPg->inStmt = 1;
+}
+static void page_remove_from_stmt_list(PgHdr *pPg){
+ if( !pPg->inStmt ) return;
+ if( pPg->pPrevStmt ){
+ assert( pPg->pPrevStmt->pNextStmt==pPg );
+ pPg->pPrevStmt->pNextStmt = pPg->pNextStmt;
+ }else{
+ assert( pPg->pPager->pStmt==pPg );
+ pPg->pPager->pStmt = pPg->pNextStmt;
+ }
+ if( pPg->pNextStmt ){
+ assert( pPg->pNextStmt->pPrevStmt==pPg );
+ pPg->pNextStmt->pPrevStmt = pPg->pPrevStmt;
+ }
+ pPg->pNextStmt = 0;
+ pPg->pPrevStmt = 0;
+ pPg->inStmt = 0;
+}
+
+/*
+** 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;
+}
+
+/*
+** Unlock the database and 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){
+ pNext = pPg->pNextAll;
+ sqliteFree(pPg);
+ }
+ pPager->pFirst = 0;
+ pPager->pFirstSynced = 0;
+ pPager->pLast = 0;
+ pPager->pAll = 0;
+ pPager->nHash = 0;
+ sqliteFree(pPager->aHash);
+ pPager->nPage = 0;
+ pPager->aHash = 0;
+ if( pPager->state>=PAGER_RESERVED ){
+ sqlite3pager_rollback(pPager);
+ }
+ sqlite3OsUnlock(pPager->fd, NO_LOCK);
+ pPager->state = PAGER_UNLOCK;
+ pPager->dbSize = -1;
+ pPager->nRef = 0;
+ assert( pPager->journalOpen==0 );
+}
+
+/*
+** When this routine is called, the pager has the journal file open and
+** a RESERVED or EXCLUSIVE lock on the database. This routine releases
+** the database lock and acquires a SHARED lock in its place. The journal
+** file is deleted and closed.
+**
+** 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_unwritelock(Pager *pPager){
+ PgHdr *pPg;
+ int rc;
+ assert( !MEMDB );
+ if( pPager->state<PAGER_RESERVED ){
+ return SQLITE_OK;
+ }
+ sqlite3pager_stmt_commit(pPager);
+ if( pPager->stmtOpen ){
+ sqlite3OsClose(&pPager->stfd);
+ pPager->stmtOpen = 0;
+ }
+ if( pPager->journalOpen ){
+ sqlite3OsClose(&pPager->jfd);
+ pPager->journalOpen = 0;
+ sqlite3OsDelete(pPager->zJournal);
+ sqliteFree( pPager->aInJournal );
+ pPager->aInJournal = 0;
+ for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
+ pPg->inJournal = 0;
+ pPg->dirty = 0;
+ pPg->needSync = 0;
+#ifdef SQLITE_CHECK_PAGES
+ pPg->pageHash = pager_pagehash(pPg);
+#endif
+ }
+ pPager->pDirty = 0;
+ pPager->dirtyCache = 0;
+ pPager->nRec = 0;
+ }else{
+ assert( pPager->aInJournal==0 );
+ assert( pPager->dirtyCache==0 || pPager->useJournal==0 );
+ }
+ rc = sqlite3OsUnlock(pPager->fd, SHARED_LOCK);
+ pPager->state = PAGER_SHARED;
+ pPager->origDbSize = 0;
+ pPager->setMaster = 0;
+ pPager->needSync = 0;
+ pPager->pFirstSynced = pPager->pFirst;
+ return 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, OsFile *jfd, 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[SQLITE_MAX_PAGE_SIZE]; /* 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) );
+
+
+ rc = read32bits(jfd, &pgno);
+ if( rc!=SQLITE_OK ) return rc;
+ rc = sqlite3OsRead(jfd, &aData, pPager->pageSize);
+ 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, &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.
+ **
+ ** 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 in the main rollback
+ ** journal. Otherwise, if a full ROLLBACK occurs after the statement
+ ** rollback the full ROLLBACK will not restore the page to its original
+ ** content. 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 in the main journal either because the page is not in
+ ** cache or else it is marked as needSync==0.
+ */
+ pPg = pager_lookup(pPager, pgno);
+ assert( pPager->state>=PAGER_EXCLUSIVE || pPg!=0 );
+ TRACE3("PLAYBACK %d page %d\n", PAGERID(pPager), pgno);
+ if( pPager->state>=PAGER_EXCLUSIVE && (pPg==0 || pPg->needSync==0) ){
+ rc = sqlite3OsSeek(pPager->fd, (pgno-1)*(i64)pPager->pageSize);
+ if( rc==SQLITE_OK ){
+ rc = sqlite3OsWrite(pPager->fd, aData, pPager->pageSize);
+ }
+ 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
+ ** sqlite3pager_rollback().
+ */
+ void *pData;
+ /* assert( pPg->nRef==0 || pPg->pgno==1 ); */
+ pData = PGHDR_TO_DATA(pPg);
+ memcpy(pData, aData, pPager->pageSize);
+ if( pPager->xDestructor ){ /*** FIX ME: Should this be xReinit? ***/
+ pPager->xDestructor(pData, pPager->pageSize);
+ }
+#ifdef SQLITE_CHECK_PAGES
+ pPg->pageHash = pager_pagehash(pPg);
+#endif
+ 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.
+**
+** 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(const char *zMaster){
+ int rc;
+ int master_open = 0;
+ OsFile *master = 0;
+ 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.
+ */
+ rc = sqlite3OsOpenReadOnly(zMaster, &master);
+ if( rc!=SQLITE_OK ) goto delmaster_out;
+ master_open = 1;
+ rc = sqlite3OsFileSize(master, &nMasterJournal);
+ if( rc!=SQLITE_OK ) goto delmaster_out;
+
+ if( nMasterJournal>0 ){
+ char *zJournal;
+ char *zMasterPtr = 0;
+
+ /* Load the entire master journal file into space obtained from
+ ** sqliteMalloc() and pointed to by zMasterJournal.
+ */
+ zMasterJournal = (char *)sqliteMalloc(nMasterJournal);
+ if( !zMasterJournal ){
+ rc = SQLITE_NOMEM;
+ goto delmaster_out;
+ }
+ rc = sqlite3OsRead(master, zMasterJournal, nMasterJournal);
+ if( rc!=SQLITE_OK ) goto delmaster_out;
+
+ zJournal = zMasterJournal;
+ while( (zJournal-zMasterJournal)<nMasterJournal ){
+ if( sqlite3OsFileExists(zJournal) ){
+ /* 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.
+ */
+ OsFile *journal = 0;
+ int c;
+
+ rc = sqlite3OsOpenReadOnly(zJournal, &journal);
+ if( rc!=SQLITE_OK ){
+ goto delmaster_out;
+ }
+
+ rc = readMasterJournal(journal, &zMasterPtr);
+ sqlite3OsClose(&journal);
+ if( rc!=SQLITE_OK ){
+ goto delmaster_out;
+ }
+
+ c = zMasterPtr!=0 && strcmp(zMasterPtr, zMaster)==0;
+ sqliteFree(zMasterPtr);
+ if( c ){
+ /* We have a match. Do not delete the master journal file. */
+ goto delmaster_out;
+ }
+ }
+ zJournal += (strlen(zJournal)+1);
+ }
+ }
+
+ sqlite3OsDelete(zMaster);
+
+delmaster_out:
+ if( zMasterJournal ){
+ sqliteFree(zMasterJournal);
+ }
+ if( master_open ){
+ sqlite3OsClose(&master);
+ }
+ return rc;
+}
+
+/*
+** Make every page in the cache agree with what is on disk. In other words,
+** reread the disk to reset the state of the cache.
+**
+** This routine is called after a rollback in which some of the dirty cache
+** pages had never been written out to disk. We need to roll back the
+** cache content and the easiest way to do that is to reread the old content
+** back from the disk.
+*/
+static int pager_reload_cache(Pager *pPager){
+ PgHdr *pPg;
+ int rc = SQLITE_OK;
+ for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
+ char zBuf[SQLITE_MAX_PAGE_SIZE];
+ if( !pPg->dirty ) continue;
+ if( (int)pPg->pgno <= pPager->origDbSize ){
+ rc = sqlite3OsSeek(pPager->fd, pPager->pageSize*(i64)(pPg->pgno-1));
+ if( rc==SQLITE_OK ){
+ rc = sqlite3OsRead(pPager->fd, zBuf, pPager->pageSize);
+ }
+ TRACE3("REFETCH %d page %d\n", PAGERID(pPager), pPg->pgno);
+ if( rc ) break;
+ CODEC1(pPager, zBuf, pPg->pgno, 2);
+ }else{
+ memset(zBuf, 0, pPager->pageSize);
+ }
+ if( pPg->nRef==0 || memcmp(zBuf, PGHDR_TO_DATA(pPg), pPager->pageSize) ){
+ memcpy(PGHDR_TO_DATA(pPg), zBuf, pPager->pageSize);
+ if( pPager->xReiniter ){
+ pPager->xReiniter(PGHDR_TO_DATA(pPg), pPager->pageSize);
+ }else{
+ memset(PGHDR_TO_EXTRA(pPg, pPager), 0, pPager->nExtra);
+ }
+ }
+ pPg->needSync = 0;
+ pPg->dirty = 0;
+#ifdef SQLITE_CHECK_PAGES
+ pPg->pageHash = pager_pagehash(pPg);
+#endif
+ }
+ pPager->pDirty = 0;
+ return rc;
+}
+
+/*
+** Truncate the main file of the given pager to the number of pages
+** indicated.
+*/
+static int pager_truncate(Pager *pPager, int nPage){
+ assert( pPager->state>=PAGER_EXCLUSIVE );
+ return sqlite3OsTruncate(pPager->fd, pPager->pageSize*(i64)nPage);
+}
+
+/*
+** 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 integer which is the number of bytes in the master journal
+** name. The value may be zero (indicate that there is no master
+** journal.)
+** (6) 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.
+** (7) 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 6 items above.
+** Each entry in the journal is an instance of the 7th 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){
+ i64 szJ; /* Size of the journal file in bytes */
+ u32 nRec; /* Number of Records in the journal */
+ int i; /* Loop counter */
+ Pgno mxPg = 0; /* Size of the original file in pages */
+ int rc; /* Result code of a subroutine */
+ 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 ){
+ 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.
+ */
+ rc = readMasterJournal(pPager->jfd, &zMaster);
+ assert( rc!=SQLITE_DONE );
+ if( rc!=SQLITE_OK || (zMaster && !sqlite3OsFileExists(zMaster)) ){
+ sqliteFree(zMaster);
+ zMaster = 0;
+ if( rc==SQLITE_DONE ) rc = SQLITE_OK;
+ goto end_playback;
+ }
+ sqlite3OsSeek(pPager->jfd, 0);
+ 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 this is the first header read from the journal, truncate the
+ ** database file back to it's original size.
+ */
+ if( pPager->state>=PAGER_EXCLUSIVE &&
+ pPager->journalOff==JOURNAL_HDR_SZ(pPager) ){
+ assert( pPager->origDbSize==0 || pPager->origDbSize==mxPg );
+ rc = pager_truncate(pPager, mxPg);
+ if( rc!=SQLITE_OK ){
+ goto end_playback;
+ }
+ pPager->dbSize = mxPg;
+ }
+
+ /* Copy original pages out of the journal and back into the database file.
+ */
+ for(i=0; i<nRec; i++){
+ rc = pager_playback_one_page(pPager, pPager->jfd, 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 ){
+ rc = pager_unwritelock(pPager);
+ }
+ if( zMaster ){
+ /* If there was a master journal and this routine will return true,
+ ** see if it is possible to delete the master journal.
+ */
+ if( rc==SQLITE_OK ){
+ rc = pager_delmaster(zMaster);
+ }
+ sqliteFree(zMaster);
+ }
+
+ /* The Pager.sectorSize variable may have been updated while rolling
+ ** back a journal created by a process with a different PAGER_SECTOR_SIZE
+ ** value. Reset it to the correct value for this process.
+ */
+ pPager->sectorSize = PAGER_SECTOR_SIZE;
+ 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;
+#ifndef NDEBUG
+ {
+ i64 os_szJ;
+ rc = sqlite3OsFileSize(pPager->jfd, &os_szJ);
+ if( rc!=SQLITE_OK ) return rc;
+ assert( szJ==os_szJ );
+ }
+#endif
+
+ /* Set hdrOff to be the offset to the first journal header written
+ ** this statement transaction, 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.
+ */
+ if( pPager->state>=PAGER_EXCLUSIVE ){
+ rc = pager_truncate(pPager, pPager->stmtSize);
+ }
+ pPager->dbSize = pPager->stmtSize;
+
+ /* Figure out how many records are in the statement journal.
+ */
+ assert( pPager->stmtInUse && pPager->journalOpen );
+ sqlite3OsSeek(pPager->stfd, 0);
+ 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=nRec-1; i>=0; i--){
+ rc = pager_playback_one_page(pPager, pPager->stfd, 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.
+ */
+ rc = sqlite3OsSeek(pPager->jfd, pPager->stmtJSize);
+ if( rc!=SQLITE_OK ){
+ goto end_stmt_playback;
+ }
+ pPager->journalOff = pPager->stmtJSize;
+ pPager->cksumInit = pPager->stmtCksum;
+ assert( JOURNAL_HDR_SZ(pPager)<(pPager->pageSize+8) );
+ while( pPager->journalOff <= (hdrOff-(pPager->pageSize+8)) ){
+ rc = pager_playback_one_page(pPager, pPager->jfd, 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, 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 sqlite3pager_set_cachesize(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 sqlite3pager_set_safety_level(Pager *pPager, int level, int full_fsync){
+ pPager->noSync = level==1 || pPager->tempFile;
+ pPager->fullSync = level==3 && !pPager->tempFile;
+ pPager->full_fsync = full_fsync;
+ 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 name of the file into zFile
+** (zFile must be at least SQLITE_TEMPNAME_SIZE bytes long.) 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 sqlite3pager_opentemp(char *zFile, OsFile **pFd){
+ int cnt = 8;
+ int rc;
+#ifdef SQLITE_TEST
+ sqlite3_opentemp_count++; /* Used for testing and analysis only */
+#endif
+ do{
+ cnt--;
+ sqlite3OsTempFileName(zFile);
+ rc = sqlite3OsOpenExclusive(zFile, pFd, 1);
+ }while( cnt>0 && rc!=SQLITE_OK && rc!=SQLITE_NOMEM );
+ 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 sqlite3pager_get() and is only held open until the
+** last page is released using sqlite3pager_unref().
+**
+** 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 sqlite3pager_open(
+ 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 */
+){
+ Pager *pPager = 0;
+ char *zFullPathname = 0;
+ int nameLen; /* Compiler is wrong. This is always initialized before use */
+ OsFile *fd;
+ 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;
+ char zTemp[SQLITE_TEMPNAME_SIZE];
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ /* A malloc() cannot fail in sqlite3ThreadData() as one or more calls to
+ ** malloc() must have already been made by this thread before it gets
+ ** to this point. This means the ThreadData must have been allocated already
+ ** so that ThreadData.nAlloc can be set. It would be nice to assert
+ ** that ThreadData.nAlloc is non-zero, but alas this breaks test cases
+ ** written to invoke the pager directly.
+ */
+ ThreadData *pTsd = sqlite3ThreadData();
+ assert( pTsd );
+#endif
+
+ /* If malloc() has already failed return SQLITE_NOMEM. Before even
+ ** testing for this, set *ppPager to NULL so the caller knows the pager
+ ** structure was never allocated.
+ */
+ *ppPager = 0;
+ if( sqlite3MallocFailed() ){
+ return SQLITE_NOMEM;
+ }
+ memset(&fd, 0, sizeof(fd));
+
+ /* Open the pager file and set zFullPathname to point at malloc()ed
+ ** memory containing the complete filename (i.e. including the directory).
+ */
+ if( zFilename && zFilename[0] ){
+#ifndef SQLITE_OMIT_MEMORYDB
+ if( strcmp(zFilename,":memory:")==0 ){
+ memDb = 1;
+ zFullPathname = sqliteStrDup("");
+ }else
+#endif
+ {
+ zFullPathname = sqlite3OsFullPathname(zFilename);
+ if( zFullPathname ){
+ rc = sqlite3OsOpenReadWrite(zFullPathname, &fd, &readOnly);
+ }
+ }
+ }else{
+ rc = sqlite3pager_opentemp(zTemp, &fd);
+ zFilename = zTemp;
+ zFullPathname = sqlite3OsFullPathname(zFilename);
+ if( rc==SQLITE_OK ){
+ tempFile = 1;
+ }
+ }
+
+ /* Allocate the Pager structure. As part of the same allocation, allocate
+ ** space for the full paths of the file, directory and journal
+ ** (Pager.zFilename, Pager.zDirectory and Pager.zJournal).
+ */
+ if( zFullPathname ){
+ nameLen = strlen(zFullPathname);
+ pPager = sqliteMalloc( sizeof(*pPager) + nameLen*3 + 30 );
+ }
+
+ /* If an error occured in either of the blocks above, free the memory
+ ** pointed to by zFullPathname, 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 || !zFullPathname || rc!=SQLITE_OK ){
+ sqlite3OsClose(&fd);
+ sqliteFree(zFullPathname);
+ sqliteFree(pPager);
+ return ((rc==SQLITE_OK)?SQLITE_NOMEM:rc);
+ }
+
+ TRACE3("OPEN %d %s\n", FILEHANDLEID(fd), zFullPathname);
+ pPager->zFilename = (char*)&pPager[1];
+ pPager->zDirectory = &pPager->zFilename[nameLen+1];
+ pPager->zJournal = &pPager->zDirectory[nameLen+1];
+ strcpy(pPager->zFilename, zFullPathname);
+ strcpy(pPager->zDirectory, zFullPathname);
+
+ for(i=nameLen; i>0 && pPager->zDirectory[i-1]!='/'; i--){}
+ if( i>0 ) pPager->zDirectory[i-1] = 0;
+ strcpy(pPager->zJournal, zFullPathname);
+ sqliteFree(zFullPathname);
+ strcpy(&pPager->zJournal[nameLen], "-journal");
+ pPager->fd = fd;
+ /* 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 = SQLITE_DEFAULT_PAGE_SIZE;
+ /* pPager->stmtSize = 0; */
+ /* pPager->stmtJSize = 0; */
+ /* pPager->nPage = 0; */
+ /* pPager->nMaxPage = 0; */
+ pPager->mxPage = 100;
+ assert( PAGER_UNLOCK==0 );
+ /* pPager->state = PAGER_UNLOCK; */
+ /* pPager->errMask = 0; */
+ pPager->tempFile = tempFile;
+ pPager->memDb = memDb;
+ pPager->readOnly = readOnly;
+ /* pPager->needSync = 0; */
+ pPager->noSync = pPager->tempFile || !useJournal;
+ pPager->fullSync = (pPager->noSync?0:1);
+ /* pPager->pFirst = 0; */
+ /* pPager->pFirstSynced = 0; */
+ /* pPager->pLast = 0; */
+ pPager->nExtra = FORCE_ALIGNMENT(nExtra);
+ pPager->sectorSize = PAGER_SECTOR_SIZE;
+ /* pPager->pBusyHandler = 0; */
+ /* memset(pPager->aHash, 0, sizeof(pPager->aHash)); */
+ *ppPager = pPager;
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ pPager->pNext = pTsd->pPager;
+ pTsd->pPager = pPager;
+#endif
+ return SQLITE_OK;
+}
+
+/*
+** Set the busy handler function.
+*/
+void sqlite3pager_set_busyhandler(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 sqlite3pager_close().
+** Destructors are only called by sqlite3pager_unref().
+*/
+void sqlite3pager_set_destructor(Pager *pPager, void (*xDesc)(void*,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 sqlite3pager_set_reiniter(Pager *pPager, void (*xReinit)(void*,int)){
+ pPager->xReiniter = xReinit;
+}
+
+/*
+** Set the page size. Return the new size. If the suggest new page
+** size is inappropriate, then an alternative page size is selected
+** and returned.
+*/
+int sqlite3pager_set_pagesize(Pager *pPager, int pageSize){
+ assert( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE );
+ if( !pPager->memDb ){
+ pPager->pageSize = pageSize;
+ }
+ return pPager->pageSize;
+}
+
+/*
+** 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 clear_simulated_io_error(){
+ sqlite3_io_error_hit = 0;
+}
+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 clear_simulated_io_error()
+# 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).
+*/
+void sqlite3pager_read_fileheader(Pager *pPager, int N, unsigned char *pDest){
+ memset(pDest, 0, N);
+ if( MEMDB==0 ){
+ disable_simulated_io_errors();
+ sqlite3OsSeek(pPager->fd, 0);
+ sqlite3OsRead(pPager->fd, pDest, N);
+ enable_simulated_io_errors();
+ }
+}
+
+/*
+** 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 sqlite3pager_pagecount(Pager *pPager){
+ i64 n;
+ assert( pPager!=0 );
+ if( pPager->dbSize>=0 ){
+ n = pPager->dbSize;
+ } else {
+ if( sqlite3OsFileSize(pPager->fd, &n)!=SQLITE_OK ){
+ pager_error(pPager, SQLITE_IOERR);
+ return 0;
+ }
+ 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++;
+ }
+ return n;
+}
+
+
+#ifndef SQLITE_OMIT_MEMORYDB
+/*
+** Clear a PgHistory block
+*/
+static void clearHistory(PgHistory *pHist){
+ sqliteFree(pHist->pOrig);
+ sqliteFree(pHist->pStmt);
+ pHist->pOrig = 0;
+ pHist->pStmt = 0;
+}
+#else
+#define clearHistory(x)
+#endif
+
+/*
+** Forward declaration
+*/
+static int syncJournal(Pager*);
+
+/*
+** Unlink pPg from it's 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
+** sqlite3pager_movepage() 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;
+
+ /* Keep the pFirstSynced pointer pointing at the first synchronized page */
+ if( pPg==pPager->pFirstSynced ){
+ PgHdr *p = pPg->pNextFree;
+ while( p && p->needSync ){ p = p->pNextFree; }
+ pPager->pFirstSynced = p;
+ }
+
+ /* Unlink from the freelist */
+ if( pPg->pPrevFree ){
+ pPg->pPrevFree->pNextFree = pPg->pNextFree;
+ }else{
+ assert( pPager->pFirst==pPg );
+ pPager->pFirst = pPg->pNextFree;
+ }
+ if( pPg->pNextFree ){
+ pPg->pNextFree->pPrevFree = pPg->pPrevFree;
+ }else{
+ assert( pPager->pLast==pPg );
+ pPager->pLast = pPg->pPrevFree;
+ }
+ pPg->pNextFree = pPg->pPrevFree = 0;
+
+ /* Unlink from the pgno hash table */
+ unlinkHashChain(pPager, pPg);
+}
+
+#ifndef SQLITE_OMIT_MEMORYDB
+/*
+** This routine is used to truncate an in-memory database. Delete
+** all pages whose pgno is larger than pPager->dbSize and is unreferenced.
+** Referenced pages larger than pPager->dbSize are zeroed.
+*/
+static void memoryTruncate(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;
+ unlinkPage(pPg);
+ makeClean(pPg);
+ sqliteFree(pPg);
+ pPager->nPage--;
+ }
+ }
+}
+#else
+#define memoryTruncate(p)
+#endif
+
+/*
+** 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;
+ assert( PAGER_SHARED==SHARED_LOCK );
+ assert( PAGER_RESERVED==RESERVED_LOCK );
+ assert( PAGER_EXCLUSIVE==EXCLUSIVE_LOCK );
+ if( pPager->state>=locktype ){
+ rc = SQLITE_OK;
+ }else{
+ do {
+ rc = sqlite3OsLock(pPager->fd, locktype);
+ }while( rc==SQLITE_BUSY && sqlite3InvokeBusyHandler(pPager->pBusyHandler) );
+ if( rc==SQLITE_OK ){
+ pPager->state = locktype;
+ }
+ }
+ return rc;
+}
+
+/*
+** Truncate the file to the number of pages specified.
+*/
+int sqlite3pager_truncate(Pager *pPager, Pgno nPage){
+ int rc;
+ sqlite3pager_pagecount(pPager);
+ if( pPager->errCode ){
+ rc = pPager->errCode;
+ return rc;
+ }
+ if( nPage>=(unsigned)pPager->dbSize ){
+ return SQLITE_OK;
+ }
+ if( MEMDB ){
+ pPager->dbSize = nPage;
+ memoryTruncate(pPager);
+ return SQLITE_OK;
+ }
+ rc = syncJournal(pPager);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+
+ /* Get an exclusive lock on the database before truncating. */
+ rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+
+ rc = pager_truncate(pPager, nPage);
+ if( rc==SQLITE_OK ){
+ pPager->dbSize = 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 sqlite3pager_close(Pager *pPager){
+ PgHdr *pPg, *pNext;
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ /* A malloc() cannot fail in sqlite3ThreadData() as one or more calls to
+ ** malloc() must have already been made by this thread before it gets
+ ** to this point. This means the ThreadData must have been allocated already
+ ** so that ThreadData.nAlloc can be set.
+ */
+ ThreadData *pTsd = sqlite3ThreadData();
+ assert( pPager );
+ assert( pTsd && pTsd->nAlloc );
+#endif
+
+ switch( pPager->state ){
+ case PAGER_RESERVED:
+ case PAGER_SYNCED:
+ case PAGER_EXCLUSIVE: {
+ /* We ignore any IO errors that occur during the rollback
+ ** operation. So disable IO error simulation so that testing
+ ** works more easily.
+ */
+ disable_simulated_io_errors();
+ sqlite3pager_rollback(pPager);
+ enable_simulated_io_errors();
+ if( !MEMDB ){
+ sqlite3OsUnlock(pPager->fd, NO_LOCK);
+ }
+ assert( pPager->errCode || pPager->journalOpen==0 );
+ break;
+ }
+ case PAGER_SHARED: {
+ if( !MEMDB ){
+ sqlite3OsUnlock(pPager->fd, NO_LOCK);
+ }
+ break;
+ }
+ default: {
+ /* Do nothing */
+ break;
+ }
+ }
+ for(pPg=pPager->pAll; pPg; pPg=pNext){
+#ifndef NDEBUG
+ if( MEMDB ){
+ PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager);
+ assert( !pPg->alwaysRollback );
+ assert( !pHist->pOrig );
+ assert( !pHist->pStmt );
+ }
+#endif
+ pNext = pPg->pNextAll;
+ sqliteFree(pPg);
+ }
+ TRACE2("CLOSE %d\n", PAGERID(pPager));
+ assert( pPager->errCode || (pPager->journalOpen==0 && pPager->stmtOpen==0) );
+ if( pPager->journalOpen ){
+ sqlite3OsClose(&pPager->jfd);
+ }
+ sqliteFree(pPager->aInJournal);
+ if( pPager->stmtOpen ){
+ sqlite3OsClose(&pPager->stfd);
+ }
+ sqlite3OsClose(&pPager->fd);
+ /* Temp files are automatically deleted by the OS
+ ** if( pPager->tempFile ){
+ ** sqlite3OsDelete(pPager->zFilename);
+ ** }
+ */
+
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+ /* Remove the pager from the linked list of pagers starting at
+ ** ThreadData.pPager if memory-management is enabled.
+ */
+ if( pPager==pTsd->pPager ){
+ pTsd->pPager = pPager->pNext;
+ }else{
+ Pager *pTmp;
+ for(pTmp = pTsd->pPager; pTmp->pNext!=pPager; pTmp=pTmp->pNext){}
+ pTmp->pNext = pPager->pNext;
+ }
+#endif
+ sqliteFree(pPager->aHash);
+ sqliteFree(pPager);
+ return SQLITE_OK;
+}
+
+/*
+** Return the page number for the given page data.
+*/
+Pgno sqlite3pager_pagenumber(void *pData){
+ PgHdr *p = DATA_TO_PGHDR(pData);
+ return p->pgno;
+}
+
+/*
+** 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. */
+ if( pPg==pPg->pPager->pFirstSynced ){
+ PgHdr *p = pPg->pNextFree;
+ while( p && p->needSync ){ p = p->pNextFree; }
+ pPg->pPager->pFirstSynced = p;
+ }
+ if( pPg->pPrevFree ){
+ pPg->pPrevFree->pNextFree = pPg->pNextFree;
+ }else{
+ pPg->pPager->pFirst = pPg->pNextFree;
+ }
+ if( pPg->pNextFree ){
+ pPg->pNextFree->pPrevFree = pPg->pPrevFree;
+ }else{
+ pPg->pPager->pLast = pPg->pPrevFree;
+ }
+ pPg->pPager->nRef++;
+ }
+ pPg->nRef++;
+ REFINFO(pPg);
+}
+#ifdef SQLITE_DEBUG
+ static void page_ref(PgHdr *pPg){
+ if( pPg->nRef==0 ){
+ _page_ref(pPg);
+ }else{
+ pPg->nRef++;
+ REFINFO(pPg);
+ }
+ }
+#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 sqlite3pager_ref(void *pData){
+ PgHdr *pPg = DATA_TO_PGHDR(pData);
+ page_ref(pPg);
+ 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 sync occurs.
+**
+** 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 ){
+ assert( pPager->journalOpen );
+ /* assert( !pPager->noSync ); // noSync might be set if synchronous
+ ** was turned off after the transaction was started. Ticket #615 */
+#ifndef NDEBUG
+ {
+ /* Make sure the pPager->nRec counter we are keeping agrees
+ ** with the nRec computed from the size of the journal file.
+ */
+ i64 jSz;
+ rc = sqlite3OsFileSize(pPager->jfd, &jSz);
+ if( rc!=0 ) return rc;
+ assert( pPager->journalOff==jSz );
+ }
+#endif
+ {
+ /* 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.
+ */
+ if( pPager->fullSync ){
+ TRACE2("SYNC journal of %d\n", PAGERID(pPager));
+ rc = sqlite3OsSync(pPager->jfd, 0);
+ if( rc!=0 ) return rc;
+ }
+ rc = sqlite3OsSeek(pPager->jfd,
+ pPager->journalHdr + sizeof(aJournalMagic));
+ if( rc ) return rc;
+ rc = write32bits(pPager->jfd, pPager->nRec);
+ if( rc ) return rc;
+
+ rc = sqlite3OsSeek(pPager->jfd, pPager->journalOff);
+ if( rc ) return rc;
+ }
+ TRACE2("SYNC journal of %d\n", PAGERID(pPager));
+ rc = sqlite3OsSync(pPager->jfd, pPager->full_fsync);
+ 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;
+ }
+ pPager->pFirstSynced = pPager->pFirst;
+ }
+
+#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->pFirstSynced==pPager->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 25
+static PgHdr *sort_pagelist(PgHdr *pIn){
+ PgHdr *a[N_SORT_BUCKET], *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 ){
+ 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;
+ 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);
+ while( pList ){
+ assert( pList->dirty );
+ rc = sqlite3OsSeek(pPager->fd, (pList->pgno-1)*(i64)pPager->pageSize);
+ if( rc ) return rc;
+ /* If there are dirty pages in the page cache with page numbers greater
+ ** than Pager.dbSize, this means sqlite3pager_truncate() 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 ){
+ char *pData = CODEC2(pPager, PGHDR_TO_DATA(pList), pList->pgno, 6);
+ TRACE3("STORE %d page %d\n", PAGERID(pPager), pList->pgno);
+ rc = sqlite3OsWrite(pPager->fd, pData, pPager->pageSize);
+ TEST_INCR(pPager->nWrite);
+ }
+#ifndef NDEBUG
+ else{
+ TRACE3("NOSTORE %d page %d\n", PAGERID(pPager), pList->pgno);
+ }
+#endif
+ if( rc ) return rc;
+ pList->dirty = 0;
+#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){
+ return pPager->pDirty;
+}
+
+/*
+** Return TRUE 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.
+*/
+static int hasHotJournal(Pager *pPager){
+ if( !pPager->useJournal ) return 0;
+ if( !sqlite3OsFileExists(pPager->zJournal) ) return 0;
+ if( sqlite3OsCheckReservedLock(pPager->fd) ) return 0;
+ if( sqlite3pager_pagecount(pPager)==0 ){
+ sqlite3OsDelete(pPager->zJournal);
+ return 0;
+ }else{
+ return 1;
+ }
+}
+
+/*
+** 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, int syncOk, PgHdr **ppPg){
+ PgHdr *pPg;
+ *ppPg = 0;
+
+ /* Find a page to recycle. Try to locate a page that does not
+ ** require us to do an fsync() on the journal.
+ */
+ pPg = pPager->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->pFirst && syncOk && !MEMDB){
+ int rc = syncJournal(pPager);
+ if( rc!=0 ){
+ return rc;
+ }
+ if( pPager->fullSync ){
+ /* 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 );
+ rc = writeJournalHdr(pPager);
+ if( rc!=0 ){
+ return rc;
+ }
+ }
+ pPg = pPager->pFirst;
+ }
+ if( pPg==0 ){
+ return SQLITE_OK;
+ }
+
+ assert( pPg->nRef==0 );
+
+ /* Write the page to the database file if it is dirty.
+ */
+ if( pPg->dirty ){
+ int rc;
+ assert( pPg->needSync==0 );
+ makeClean(pPg);
+ pPg->dirty = 1;
+ pPg->pDirty = 0;
+ rc = pager_write_pagelist( pPg );
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ }
+ assert( pPg->dirty==0 );
+
+ /* If the page we are recycling is marked as alwaysRollback, then
+ ** set the global alwaysRollback flag, thus disabling the
+ ** sqlite_dont_rollback() 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 ){
+ pPager->alwaysRollback = 1;
+ }
+
+ /* Unlink the old page from the free list and the hash table
+ */
+ unlinkPage(pPg);
+ TEST_INCR(pPager->nOvfl);
+
+ *ppPg = pPg;
+ return SQLITE_OK;
+}
+
+/*
+** 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 sqliteFree()ed.
+**
+** nReq is the number of bytes of memory required. Once this much has
+** been released, the function returns. A negative value for nReq means
+** free as much memory as possible. The return value is the total number
+** of bytes of memory released.
+*/
+#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
+int sqlite3pager_release_memory(int nReq){
+ const ThreadData *pTsdro = sqlite3ThreadDataReadOnly();
+ Pager *p;
+ int nReleased = 0;
+ int i;
+
+ /* If the the global mutex is held, this subroutine becomes a
+ ** o-op; zero bytes of memory are freed. This is because
+ ** some of the code invoked by this function may also
+ ** try to obtain the mutex, resulting in a deadlock.
+ */
+ if( sqlite3OsInMutex(0) ){
+ return 0;
+ }
+
+ /* Outermost loop runs for at most two iterations. First iteration we
+ ** try to find memory that can be released without calling fsync(). Second
+ ** iteration (which only runs if the first failed to free nReq bytes of
+ ** memory) is permitted to call fsync(). This is of course much more
+ ** expensive.
+ */
+ for(i=0; i<=1; i++){
+
+ /* Loop through all the SQLite pagers opened by the current thread. */
+ for(p=pTsdro->pPager; p && (nReq<0 || nReleased<nReq); p=p->pNext){
+ PgHdr *pPg;
+ int rc;
+
+ /* For each pager, try to free as many pages as possible (without
+ ** calling fsync() if this is the first iteration of the outermost
+ ** loop).
+ */
+ while( SQLITE_OK==(rc = pager_recycle(p, i, &pPg)) && pPg) {
+ /* 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 );
+ page_remove_from_stmt_list(pPg);
+ if( pPg==p->pAll ){
+ p->pAll = pPg->pNextAll;
+ }else{
+ for( pTmp=p->pAll; pTmp->pNextAll!=pPg; pTmp=pTmp->pNextAll ){}
+ pTmp->pNextAll = pPg->pNextAll;
+ }
+ nReleased += sqliteAllocSize(pPg);
+ sqliteFree(pPg);
+ }
+
+ if( rc!=SQLITE_OK ){
+ /* 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==SQLITE_IOERR || rc==SQLITE_FULL );
+ assert( p->state>=PAGER_RESERVED );
+ pager_error(p, rc);
+ }
+ }
+ }
+
+ return nReleased;
+}
+#endif /* SQLITE_ENABLE_MEMORY_MANAGEMENT */
+
+/*
+** 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.
+**
+** A _get 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 sqlite3pager_lookup(). 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.
+*/
+int sqlite3pager_get(Pager *pPager, Pgno pgno, void **ppPage){
+ PgHdr *pPg;
+ int rc;
+
+ /* 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( pPager->errCode && pPager->errCode!=SQLITE_FULL ){
+ return pPager->errCode;
+ }
+
+ /* If this is the first page accessed, then get a SHARED lock
+ ** on the database file.
+ */
+ if( pPager->nRef==0 && !MEMDB ){
+ if( !pPager->noReadlock ){
+ rc = pager_wait_on_lock(pPager, SHARED_LOCK);
+ if( rc!=SQLITE_OK ){
+ return pager_error(pPager, rc);
+ }
+ }
+
+ /* 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( hasHotJournal(pPager) ){
+ /* 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 it's own EXCLUSIVE lock on the database file.
+ */
+ rc = sqlite3OsLock(pPager->fd, EXCLUSIVE_LOCK);
+ if( rc!=SQLITE_OK ){
+ sqlite3OsUnlock(pPager->fd, NO_LOCK);
+ pPager->state = PAGER_UNLOCK;
+ return pager_error(pPager, rc);
+ }
+ pPager->state = PAGER_EXCLUSIVE;
+
+ /* Open the journal for reading only. Return SQLITE_BUSY if
+ ** we are unable to open the journal file.
+ **
+ ** The journal file does not need to be locked itself. The
+ ** journal file is never open unless the main database file holds
+ ** a write lock, so there is never any chance of two or more
+ ** processes opening the journal at the same time.
+ */
+ rc = sqlite3OsOpenReadOnly(pPager->zJournal, &pPager->jfd);
+ if( rc!=SQLITE_OK ){
+ sqlite3OsUnlock(pPager->fd, NO_LOCK);
+ pPager->state = PAGER_UNLOCK;
+ return SQLITE_BUSY;
+ }
+ 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);
+ if( rc!=SQLITE_OK ){
+ return pager_error(pPager, rc);
+ }
+ }
+ pPg = 0;
+ }else{
+ /* Search for page in cache */
+ pPg = pager_lookup(pPager, pgno);
+ if( MEMDB && pPager->state==PAGER_UNLOCK ){
+ pPager->state = PAGER_SHARED;
+ }
+ }
+ if( pPg==0 ){
+ /* The requested page is not in the page cache. */
+ int h;
+ TEST_INCR(pPager->nMiss);
+ if( pPager->nPage<pPager->mxPage || pPager->pFirst==0 || MEMDB ){
+ /* Create a new page */
+ if( pPager->nPage>=pPager->nHash ){
+ pager_resize_hash_table(pPager,
+ pPager->nHash<256 ? 256 : pPager->nHash*2);
+ if( pPager->nHash==0 ){
+ return SQLITE_NOMEM;
+ }
+ }
+ pPg = sqliteMallocRaw( sizeof(*pPg) + pPager->pageSize
+ + sizeof(u32) + pPager->nExtra
+ + MEMDB*sizeof(PgHistory) );
+ if( pPg==0 ){
+ return SQLITE_NOMEM;
+ }
+ memset(pPg, 0, sizeof(*pPg));
+ if( MEMDB ){
+ memset(PGHDR_TO_HIST(pPg, pPager), 0, sizeof(PgHistory));
+ }
+ pPg->pPager = pPager;
+ pPg->pNextAll = pPager->pAll;
+ pPager->pAll = pPg;
+ pPager->nPage++;
+ if( pPager->nPage>pPager->nMaxPage ){
+ assert( pPager->nMaxPage==(pPager->nPage-1) );
+ pPager->nMaxPage++;
+ }
+ }else{
+ rc = pager_recycle(pPager, 1, &pPg);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ assert(pPg) ;
+ }
+ pPg->pgno = pgno;
+ if( pPager->aInJournal && (int)pgno<=pPager->origDbSize ){
+ sqlite3CheckMemory(pPager->aInJournal, pgno/8);
+ assert( pPager->journalOpen );
+ pPg->inJournal = (pPager->aInJournal[pgno/8] & (1<<(pgno&7)))!=0;
+ pPg->needSync = 0;
+ }else{
+ pPg->inJournal = 0;
+ pPg->needSync = 0;
+ }
+ if( pPager->aInStmt && (int)pgno<=pPager->stmtSize
+ && (pPager->aInStmt[pgno/8] & (1<<(pgno&7)))!=0 ){
+ page_add_to_stmt_list(pPg);
+ }else{
+ page_remove_from_stmt_list(pPg);
+ }
+ makeClean(pPg);
+ pPg->nRef = 1;
+ REFINFO(pPg);
+
+ pPager->nRef++;
+ if( pPager->nExtra>0 ){
+ memset(PGHDR_TO_EXTRA(pPg, pPager), 0, pPager->nExtra);
+ }
+ if( pPager->errCode ){
+ sqlite3pager_unref(PGHDR_TO_DATA(pPg));
+ rc = pPager->errCode;
+ return rc;
+ }
+
+ /* Populate the page with data, either by reading from the database
+ ** file, or by setting the entire page to zero.
+ */
+ if( sqlite3pager_pagecount(pPager)<(int)pgno || MEMDB ){
+ memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
+ }else{
+ assert( MEMDB==0 );
+ rc = sqlite3OsSeek(pPager->fd, (pgno-1)*(i64)pPager->pageSize);
+ if( rc==SQLITE_OK ){
+ rc = sqlite3OsRead(pPager->fd, PGHDR_TO_DATA(pPg),
+ pPager->pageSize);
+ }
+ TRACE3("FETCH %d page %d\n", PAGERID(pPager), pPg->pgno);
+ CODEC1(pPager, PGHDR_TO_DATA(pPg), pPg->pgno, 3);
+ if( rc!=SQLITE_OK ){
+ i64 fileSize;
+ int rc2 = sqlite3OsFileSize(pPager->fd, &fileSize);
+ if( rc2!=SQLITE_OK || fileSize>=pgno*pPager->pageSize ){
+ /* An IO error occured in one of the the sqlite3OsSeek() or
+ ** sqlite3OsRead() calls above. */
+ pPg->pgno = 0;
+ sqlite3pager_unref(PGHDR_TO_DATA(pPg));
+ return rc;
+ }else{
+ clear_simulated_io_error();
+ memset(PGHDR_TO_DATA(pPg), 0, pPager->pageSize);
+ }
+ }else{
+ TEST_INCR(pPager->nRead);
+ }
+ }
+
+ /* 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. */
+ TEST_INCR(pPager->nHit);
+ page_ref(pPg);
+ }
+ *ppPage = PGHDR_TO_DATA(pPg);
+ return SQLITE_OK;
+}
+
+/*
+** 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 sqlite3pager_get(). The difference between this routine
+** and sqlite3pager_get() 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.
+*/
+void *sqlite3pager_lookup(Pager *pPager, Pgno pgno){
+ PgHdr *pPg;
+
+ assert( pPager!=0 );
+ assert( pgno!=0 );
+ if( pPager->errCode && pPager->errCode!=SQLITE_FULL ){
+ return 0;
+ }
+ pPg = pager_lookup(pPager, pgno);
+ if( pPg==0 ) return 0;
+ page_ref(pPg);
+ return PGHDR_TO_DATA(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 sqlite3pager_unref(void *pData){
+ PgHdr *pPg;
+
+ /* Decrement the reference count for this page
+ */
+ pPg = DATA_TO_PGHDR(pData);
+ assert( pPg->nRef>0 );
+ pPg->nRef--;
+ REFINFO(pPg);
+
+ 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 ){
+ Pager *pPager;
+ pPager = pPg->pPager;
+ pPg->pNextFree = 0;
+ pPg->pPrevFree = pPager->pLast;
+ pPager->pLast = pPg;
+ if( pPg->pPrevFree ){
+ pPg->pPrevFree->pNextFree = pPg;
+ }else{
+ pPager->pFirst = pPg;
+ }
+ if( pPg->needSync==0 && pPager->pFirstSynced==0 ){
+ pPager->pFirstSynced = pPg;
+ }
+ if( pPager->xDestructor ){
+ pPager->xDestructor(pData, 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 && !MEMDB ){
+ pager_reset(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){
+ int rc;
+ assert( !MEMDB );
+ assert( pPager->state>=PAGER_RESERVED );
+ assert( pPager->journalOpen==0 );
+ assert( pPager->useJournal );
+ assert( pPager->aInJournal==0 );
+ sqlite3pager_pagecount(pPager);
+ pPager->aInJournal = sqliteMalloc( pPager->dbSize/8 + 1 );
+ if( pPager->aInJournal==0 ){
+ rc = SQLITE_NOMEM;
+ goto failed_to_open_journal;
+ }
+ rc = sqlite3OsOpenExclusive(pPager->zJournal, &pPager->jfd,
+ pPager->tempFile);
+ pPager->journalOff = 0;
+ pPager->setMaster = 0;
+ pPager->journalHdr = 0;
+ if( rc!=SQLITE_OK ){
+ goto failed_to_open_journal;
+ }
+ sqlite3OsSetFullSync(pPager->jfd, pPager->full_fsync);
+ sqlite3OsSetFullSync(pPager->fd, pPager->full_fsync);
+ sqlite3OsOpenDirectory(pPager->jfd, pPager->zDirectory);
+ 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 = sqlite3pager_stmt_begin(pPager);
+ }
+ if( rc!=SQLITE_OK && rc!=SQLITE_NOMEM ){
+ rc = pager_unwritelock(pPager);
+ if( rc==SQLITE_OK ){
+ rc = SQLITE_FULL;
+ }
+ }
+ return rc;
+
+failed_to_open_journal:
+ sqliteFree(pPager->aInJournal);
+ pPager->aInJournal = 0;
+ if( rc==SQLITE_NOMEM ){
+ /* If this was a malloc() failure, then we will not be closing the pager
+ ** file. So delete any journal file we may have just created. Otherwise,
+ ** the system will get confused, we have a read-lock on the file and a
+ ** mysterious journal has appeared in the filesystem.
+ */
+ sqlite3OsDelete(pPager->zJournal);
+ }else{
+ sqlite3OsUnlock(pPager->fd, NO_LOCK);
+ pPager->state = PAGER_UNLOCK;
+ }
+ return rc;
+}
+
+/*
+** Acquire a write-lock on the database. The lock is removed when
+** the any of the following happen:
+**
+** * sqlite3pager_commit() is called.
+** * sqlite3pager_rollback() is called.
+** * sqlite3pager_close() is called.
+** * sqlite3pager_unref() 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 sqlite3pager_begin(void *pData, int exFlag){
+ PgHdr *pPg = DATA_TO_PGHDR(pData);
+ Pager *pPager = pPg->pPager;
+ int rc = SQLITE_OK;
+ assert( pPg->nRef>0 );
+ assert( pPager->state!=PAGER_UNLOCK );
+ if( pPager->state==PAGER_SHARED ){
+ assert( pPager->aInJournal==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 ){
+ return rc;
+ }
+ pPager->dirtyCache = 0;
+ TRACE2("TRANSACTION %d\n", PAGERID(pPager));
+ if( pPager->useJournal && !pPager->tempFile ){
+ rc = pager_open_journal(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 ){
+ pPg->pDirty->pPrevDirty = pPg->pPrevDirty;
+ }
+ if( pPg->pPrevDirty ){
+ pPg->pPrevDirty->pDirty = pPg->pDirty;
+ }else{
+ 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 sqlite3pager_commit() or sqlite3pager_rollback() to
+** reset.
+*/
+int sqlite3pager_write(void *pData){
+ PgHdr *pPg = DATA_TO_PGHDR(pData);
+ 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);
+
+ /* 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 && (pPg->inStmt || pPager->stmtInUse==0) ){
+ pPager->dirtyCache = 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 = sqlite3pager_begin(pData, 0);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ assert( pPager->state>=PAGER_RESERVED );
+ if( !pPager->journalOpen && pPager->useJournal ){
+ rc = pager_open_journal(pPager);
+ if( rc!=SQLITE_OK ) return rc;
+ }
+ assert( pPager->journalOpen || !pPager->useJournal );
+ pPager->dirtyCache = 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->useJournal || MEMDB) ){
+ if( (int)pPg->pgno <= pPager->origDbSize ){
+ int szPg;
+ if( MEMDB ){
+ PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager);
+ TRACE3("JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
+ assert( pHist->pOrig==0 );
+ pHist->pOrig = sqliteMallocRaw( pPager->pageSize );
+ if( pHist->pOrig ){
+ memcpy(pHist->pOrig, PGHDR_TO_DATA(pPg), pPager->pageSize);
+ }
+ }else{
+ u32 cksum, saved;
+ char *pData2, *pEnd;
+ /* 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);
+ pEnd = pData2 + pPager->pageSize;
+ pData2 -= 4;
+ saved = *(u32*)pEnd;
+ put32bits(pEnd, cksum);
+ szPg = pPager->pageSize+8;
+ put32bits(pData2, pPg->pgno);
+ rc = sqlite3OsWrite(pPager->jfd, pData2, szPg);
+ pPager->journalOff += szPg;
+ TRACE4("JOURNAL %d page %d needSync=%d\n",
+ PAGERID(pPager), pPg->pgno, pPg->needSync);
+ *(u32*)pEnd = saved;
+
+ /* 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->aInJournal!=0 );
+ pPager->aInJournal[pPg->pgno/8] |= 1<<(pPg->pgno&7);
+ pPg->needSync = !pPager->noSync;
+ if( pPager->stmtInUse ){
+ pPager->aInStmt[pPg->pgno/8] |= 1<<(pPg->pgno&7);
+ page_add_to_stmt_list(pPg);
+ }
+ }
+ }else{
+ pPg->needSync = !pPager->journalStarted && !pPager->noSync;
+ TRACE4("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 && !pPg->inStmt && (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 = sqliteMallocRaw( pPager->pageSize );
+ if( pHist->pStmt ){
+ memcpy(pHist->pStmt, PGHDR_TO_DATA(pPg), pPager->pageSize);
+ }
+ TRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
+ }else{
+ char *pData2 = CODEC2(pPager, pData, pPg->pgno, 7)-4;
+ put32bits(pData2, pPg->pgno);
+ rc = sqlite3OsWrite(pPager->stfd, pData2, pPager->pageSize+4);
+ TRACE3("STMT-JOURNAL %d page %d\n", PAGERID(pPager), pPg->pgno);
+ if( rc!=SQLITE_OK ){
+ return rc;
+ }
+ pPager->stmtNRec++;
+ assert( pPager->aInStmt!=0 );
+ pPager->aInStmt[pPg->pgno/8] |= 1<<(pPg->pgno&7);
+ }
+ page_add_to_stmt_list(pPg);
+ }
+ }
+
+ /* Update the database size and return.
+ */
+ if( pPager->dbSize<(int)pPg->pgno ){
+ pPager->dbSize = pPg->pgno;
+ if( !MEMDB && pPager->dbSize==PENDING_BYTE/pPager->pageSize ){
+ pPager->dbSize++;
+ }
+ }
+ return rc;
+}
+
+/*
+** Return TRUE if the page given in the argument was previously passed
+** to sqlite3pager_write(). In other words, return TRUE if it is ok
+** to change the content of the page.
+*/
+#ifndef NDEBUG
+int sqlite3pager_iswriteable(void *pData){
+ PgHdr *pPg = DATA_TO_PGHDR(pData);
+ return pPg->dirty;
+}
+#endif
+
+#ifndef SQLITE_OMIT_VACUUM
+/*
+** Replace the content of a single page with the information in the third
+** argument.
+*/
+int sqlite3pager_overwrite(Pager *pPager, Pgno pgno, void *pData){
+ void *pPage;
+ int rc;
+
+ rc = sqlite3pager_get(pPager, pgno, &pPage);
+ if( rc==SQLITE_OK ){
+ rc = sqlite3pager_write(pPage);
+ if( rc==SQLITE_OK ){
+ memcpy(pPage, pData, pPager->pageSize);
+ }
+ sqlite3pager_unref(pPage);
+ }
+ return rc;
+}
+#endif
+
+/*
+** A call to this routine tells the pager that it is not necessary to
+** write the information on page "pgno" 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
+** sqlite3pager_dont_rollback() 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 sqlite3pager_dont_rollback() 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 dont_rollback() routine is called. But because the page contains
+** critical data, we still need to be sure it gets rolled back in spite
+** of the dont_rollback() call.
+*/
+void sqlite3pager_dont_write(Pager *pPager, Pgno pgno){
+ PgHdr *pPg;
+
+ if( MEMDB ) return;
+
+ pPg = pager_lookup(pPager, pgno);
+ assert( pPg!=0 ); /* We never call _dont_write unless the page is in mem */
+ pPg->alwaysRollback = 1;
+ if( pPg->dirty && !pPager->stmtInUse ){
+ 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{
+ TRACE3("DONT_WRITE page %d of %d\n", pgno, PAGERID(pPager));
+ makeClean(pPg);
+#ifdef SQLITE_CHECK_PAGES
+ pPg->pageHash = pager_pagehash(pPg);
+#endif
+ }
+ }
+}
+
+/*
+** 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.
+*/
+void sqlite3pager_dont_rollback(void *pData){
+ PgHdr *pPg = DATA_TO_PGHDR(pData);
+ Pager *pPager = pPg->pPager;
+
+ if( pPager->state!=PAGER_EXCLUSIVE || pPager->journalOpen==0 ) return;
+ if( pPg->alwaysRollback || pPager->alwaysRollback || MEMDB ) return;
+ if( !pPg->inJournal && (int)pPg->pgno <= pPager->origDbSize ){
+ assert( pPager->aInJournal!=0 );
+ pPager->aInJournal[pPg->pgno/8] |= 1<<(pPg->pgno&7);
+ pPg->inJournal = 1;
+ if( pPager->stmtInUse ){
+ pPager->aInStmt[pPg->pgno/8] |= 1<<(pPg->pgno&7);
+ page_add_to_stmt_list(pPg);
+ }
+ TRACE3("DONT_ROLLBACK page %d of %d\n", pPg->pgno, PAGERID(pPager));
+ }
+ if( pPager->stmtInUse && !pPg->inStmt && (int)pPg->pgno<=pPager->stmtSize ){
+ assert( pPg->inJournal || (int)pPg->pgno>pPager->origDbSize );
+ assert( pPager->aInStmt!=0 );
+ pPager->aInStmt[pPg->pgno/8] |= 1<<(pPg->pgno&7);
+ page_add_to_stmt_list(pPg);
+ }
+}
+
+
+/*
+** 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 sqlite3pager_commit(Pager *pPager){
+ int rc;
+ PgHdr *pPg;
+
+ if( pPager->errCode ){
+ return pPager->errCode;
+ }
+ if( pPager->state<PAGER_RESERVED ){
+ return SQLITE_ERROR;
+ }
+ TRACE2("COMMIT %d\n", PAGERID(pPager));
+ if( MEMDB ){
+ pPg = pager_get_all_dirty_pages(pPager);
+ while( pPg ){
+ clearHistory(PGHDR_TO_HIST(pPg, pPager));
+ pPg->dirty = 0;
+ pPg->inJournal = 0;
+ pPg->inStmt = 0;
+ pPg->needSync = 0;
+ pPg->pPrevStmt = pPg->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;
+ return SQLITE_OK;
+ }
+ if( pPager->dirtyCache==0 ){
+ /* Exit early (without doing the time-consuming sqlite3OsSync() calls)
+ ** if there have been no changes to the database file. */
+ assert( pPager->needSync==0 );
+ rc = pager_unwritelock(pPager);
+ pPager->dbSize = -1;
+ return rc;
+ }
+ assert( pPager->journalOpen );
+ rc = sqlite3pager_sync(pPager, 0, 0);
+ if( rc==SQLITE_OK ){
+ rc = pager_unwritelock(pPager);
+ pPager->dbSize = -1;
+ }
+ 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 (SQLITE_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 sqlite3pager_rollback(Pager *pPager){
+ int rc;
+ TRACE2("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);
+ TRACE3("ROLLBACK-PAGE %d of %d\n", p->pgno, PAGERID(pPager));
+ }else{
+ TRACE3("PAGE %d is clean on %d\n", p->pgno, PAGERID(pPager));
+ }
+ clearHistory(pHist);
+ p->dirty = 0;
+ p->inJournal = 0;
+ p->inStmt = 0;
+ p->pPrevStmt = p->pNextStmt = 0;
+ if( pPager->xReiniter ){
+ pPager->xReiniter(PGHDR_TO_DATA(p), pPager->pageSize);
+ }
+ }
+ pPager->pDirty = 0;
+ pPager->pStmt = 0;
+ pPager->dbSize = pPager->origDbSize;
+ memoryTruncate(pPager);
+ pPager->stmtInUse = 0;
+ pPager->state = PAGER_SHARED;
+ return SQLITE_OK;
+ }
+
+ if( !pPager->dirtyCache || !pPager->journalOpen ){
+ rc = pager_unwritelock(pPager);
+ pPager->dbSize = -1;
+ return rc;
+ }
+
+ if( pPager->errCode && pPager->errCode!=SQLITE_FULL ){
+ if( pPager->state>=PAGER_EXCLUSIVE ){
+ pager_playback(pPager);
+ }
+ return pPager->errCode;
+ }
+ if( pPager->state==PAGER_RESERVED ){
+ int rc2;
+ rc = pager_reload_cache(pPager);
+ rc2 = pager_unwritelock(pPager);
+ if( rc==SQLITE_OK ){
+ rc = rc2;
+ }
+ }else{
+ rc = pager_playback(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.
+ */
+ return pager_error(pPager, rc);
+}
+
+/*
+** Return TRUE if the database file is opened read-only. Return FALSE
+** if the database is (in theory) writable.
+*/
+int sqlite3pager_isreadonly(Pager *pPager){
+ return pPager->readOnly;
+}
+
+/*
+** Return the number of references to the pager.
+*/
+int sqlite3pager_refcount(Pager *pPager){
+ return pPager->nRef;
+}
+
+#ifdef SQLITE_TEST
+/*
+** This routine is used for testing and analysis only.
+*/
+int *sqlite3pager_stats(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] = pPager->nOvfl;
+ a[9] = pPager->nRead;
+ a[10] = pPager->nWrite;
+ return a;
+}
+#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.
+*/
+int sqlite3pager_stmt_begin(Pager *pPager){
+ int rc;
+ char zTemp[SQLITE_TEMPNAME_SIZE];
+ assert( !pPager->stmtInUse );
+ assert( pPager->dbSize>=0 );
+ TRACE2("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 );
+ pPager->aInStmt = sqliteMalloc( pPager->dbSize/8 + 1 );
+ if( pPager->aInStmt==0 ){
+ /* sqlite3OsLock(pPager->fd, SHARED_LOCK); */
+ return SQLITE_NOMEM;
+ }
+#ifndef NDEBUG
+ rc = sqlite3OsFileSize(pPager->jfd, &pPager->stmtJSize);
+ if( rc ) goto stmt_begin_failed;
+ assert( pPager->stmtJSize == pPager->journalOff );
+#endif
+ pPager->stmtJSize = pPager->journalOff;
+ pPager->stmtSize = pPager->dbSize;
+ pPager->stmtHdrOff = 0;
+ pPager->stmtCksum = pPager->cksumInit;
+ if( !pPager->stmtOpen ){
+ rc = sqlite3pager_opentemp(zTemp, &pPager->stfd);
+ if( rc ) goto stmt_begin_failed;
+ pPager->stmtOpen = 1;
+ pPager->stmtNRec = 0;
+ }
+ pPager->stmtInUse = 1;
+ return SQLITE_OK;
+
+stmt_begin_failed:
+ if( pPager->aInStmt ){
+ sqliteFree(pPager->aInStmt);
+ pPager->aInStmt = 0;
+ }
+ return rc;
+}
+
+/*
+** Commit a statement.
+*/
+int sqlite3pager_stmt_commit(Pager *pPager){
+ if( pPager->stmtInUse ){
+ PgHdr *pPg, *pNext;
+ TRACE2("STMT-COMMIT %d\n", PAGERID(pPager));
+ if( !MEMDB ){
+ sqlite3OsSeek(pPager->stfd, 0);
+ /* sqlite3OsTruncate(pPager->stfd, 0); */
+ sqliteFree( pPager->aInStmt );
+ pPager->aInStmt = 0;
+ }
+ for(pPg=pPager->pStmt; pPg; pPg=pNext){
+ pNext = pPg->pNextStmt;
+ assert( pPg->inStmt );
+ pPg->inStmt = 0;
+ pPg->pPrevStmt = pPg->pNextStmt = 0;
+ if( MEMDB ){
+ PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager);
+ sqliteFree(pHist->pStmt);
+ pHist->pStmt = 0;
+ }
+ }
+ pPager->stmtNRec = 0;
+ pPager->stmtInUse = 0;
+ pPager->pStmt = 0;
+ }
+ pPager->stmtAutoopen = 0;
+ return SQLITE_OK;
+}
+
+/*
+** Rollback a statement.
+*/
+int sqlite3pager_stmt_rollback(Pager *pPager){
+ int rc;
+ if( pPager->stmtInUse ){
+ TRACE2("STMT-ROLLBACK %d\n", PAGERID(pPager));
+ if( MEMDB ){
+ PgHdr *pPg;
+ for(pPg=pPager->pStmt; pPg; pPg=pPg->pNextStmt){
+ PgHistory *pHist = PGHDR_TO_HIST(pPg, pPager);
+ if( pHist->pStmt ){
+ memcpy(PGHDR_TO_DATA(pPg), pHist->pStmt, pPager->pageSize);
+ sqliteFree(pHist->pStmt);
+ pHist->pStmt = 0;
+ }
+ }
+ pPager->dbSize = pPager->stmtSize;
+ memoryTruncate(pPager);
+ rc = SQLITE_OK;
+ }else{
+ rc = pager_stmt_playback(pPager);
+ }
+ sqlite3pager_stmt_commit(pPager);
+ }else{
+ rc = SQLITE_OK;
+ }
+ pPager->stmtAutoopen = 0;
+ return rc;
+}
+
+/*
+** Return the full pathname of the database file.
+*/
+const char *sqlite3pager_filename(Pager *pPager){
+ return pPager->zFilename;
+}
+
+/*
+** Return the directory of the database file.
+*/
+const char *sqlite3pager_dirname(Pager *pPager){
+ return pPager->zDirectory;
+}
+
+/*
+** Return the full pathname of the journal file.
+*/
+const char *sqlite3pager_journalname(Pager *pPager){
+ return pPager->zJournal;
+}
+
+/*
+** Return true if fsync() calls are disabled for this pager. Return FALSE
+** if fsync()s are executed normally.
+*/
+int sqlite3pager_nosync(Pager *pPager){
+ return pPager->noSync;
+}
+
+/*
+** Set the codec for this pager
+*/
+void sqlite3pager_set_codec(
+ Pager *pPager,
+ void *(*xCodec)(void*,void*,Pgno,int),
+ void *pCodecArg
+){
+ pPager->xCodec = xCodec;
+ pPager->pCodecArg = pCodecArg;
+}
+
+/*
+** 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){
+ void *pPage;
+ PgHdr *pPgHdr;
+ u32 change_counter;
+ int rc;
+
+ /* Open page 1 of the file for writing. */
+ rc = sqlite3pager_get(pPager, 1, &pPage);
+ if( rc!=SQLITE_OK ) return rc;
+ rc = sqlite3pager_write(pPage);
+ if( rc!=SQLITE_OK ) return rc;
+
+ /* Read the current value at byte 24. */
+ pPgHdr = DATA_TO_PGHDR(pPage);
+ change_counter = retrieve32bits(pPgHdr, 24);
+
+ /* Increment the value just read and write it back to byte 24. */
+ change_counter++;
+ put32bits(((char*)PGHDR_TO_DATA(pPgHdr))+24, change_counter);
+
+ /* Release the page reference. */
+ sqlite3pager_unref(pPage);
+ return SQLITE_OK;
+}
+
+/*
+** 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 sqlite3pager_sync() call.
+**
+** If parameter nTrunc is non-zero, then the pager file is truncated to
+** nTrunc pages (this is used by auto-vacuum databases).
+*/
+int sqlite3pager_sync(Pager *pPager, const char *zMaster, Pgno nTrunc){
+ int rc = SQLITE_OK;
+
+ TRACE4("DATABASE SYNC: File=%s zMaster=%s nTrunc=%d\n",
+ pPager->zFilename, zMaster, nTrunc);
+
+ /* 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;
+ assert( pPager->journalOpen );
+
+ /* 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);
+ if( rc!=SQLITE_OK ) goto sync_exit;
+#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;
+ void *pPage;
+ int iSkip = PAGER_MJ_PGNO(pPager);
+ for( i=nTrunc+1; i<=pPager->origDbSize; i++ ){
+ if( !(pPager->aInJournal[i/8] & (1<<(i&7))) && i!=iSkip ){
+ rc = sqlite3pager_get(pPager, i, &pPage);
+ if( rc!=SQLITE_OK ) goto sync_exit;
+ rc = sqlite3pager_write(pPage);
+ sqlite3pager_unref(pPage);
+ 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 = sqlite3pager_truncate(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 ) goto sync_exit;
+
+ /* Sync the database file. */
+ if( !pPager->noSync ){
+ rc = sqlite3OsSync(pPager->fd, 0);
+ }
+
+ pPager->state = PAGER_SYNCED;
+ }else if( MEMDB && nTrunc!=0 ){
+ rc = sqlite3pager_truncate(pPager, nTrunc);
+ }
+
+sync_exit:
+ return rc;
+}
+
+#ifndef SQLITE_OMIT_AUTOVACUUM
+/*
+** Move the page identified by pData to location pgno in the file.
+**
+** There must be no references to the current page pgno. If current page
+** pgno is not already in the rollback journal, it is not written there by
+** by this routine. The same applies to the page pData refers to on entry to
+** this routine.
+**
+** References to the page refered to by pData remain valid. Updating any
+** meta-data associated with page pData (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).
+*/
+int sqlite3pager_movepage(Pager *pPager, void *pData, Pgno pgno){
+ PgHdr *pPg = DATA_TO_PGHDR(pData);
+ PgHdr *pPgOld;
+ int h;
+ Pgno needSyncPgno = 0;
+
+ assert( pPg->nRef>0 );
+
+ TRACE5("MOVE %d page %d (needSync=%d) moves to %d\n",
+ PAGERID(pPager), pPg->pgno, pPg->needSync, pgno);
+
+ if( pPg->needSync ){
+ needSyncPgno = pPg->pgno;
+ assert( pPg->inJournal );
+ assert( pPg->dirty );
+ assert( pPager->needSync );
+ }
+
+ /* Unlink pPg from it's hash-chain */
+ unlinkHashChain(pPager, pPg);
+
+ /* If the cache contains a page with page-number pgno, remove it
+ ** from it's 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.
+ */
+ pPgOld = pager_lookup(pPager, pgno);
+ if( pPgOld ){
+ assert( pPgOld->nRef==0 );
+ unlinkHashChain(pPager, pPgOld);
+ makeClean(pPgOld);
+ if( pPgOld->needSync ){
+ assert( pPgOld->inJournal );
+ pPg->inJournal = 1;
+ pPg->needSync = 1;
+ assert( pPager->needSync );
+ }
+ }
+
+ /* 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;
+
+ 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
+ ** Pager.aInJournal bit has been set. This needs to be remedied by loading
+ ** the page into the pager-cache and setting the PgHdr.needSync flag.
+ **
+ ** The sqlite3pager_get() call may cause the journal to sync. So make
+ ** sure the Pager.needSync flag is set too.
+ */
+ int rc;
+ void *pNeedSync;
+ assert( pPager->needSync );
+ rc = sqlite3pager_get(pPager, needSyncPgno, &pNeedSync);
+ if( rc!=SQLITE_OK ) return rc;
+ pPager->needSync = 1;
+ DATA_TO_PGHDR(pNeedSync)->needSync = 1;
+ DATA_TO_PGHDR(pNeedSync)->inJournal = 1;
+ makeDirty(DATA_TO_PGHDR(pNeedSync));
+ sqlite3pager_unref(pNeedSync);
+ }
+
+ return SQLITE_OK;
+}
+#endif
+
+#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
+/*
+** Return the current state of the file lock for the given pager.
+** The return value is one of NO_LOCK, SHARED_LOCK, RESERVED_LOCK,
+** PENDING_LOCK, or EXCLUSIVE_LOCK.
+*/
+int sqlite3pager_lockstate(Pager *pPager){
+ return sqlite3OsLockState(pPager->fd);
+}
+#endif
+
+#ifdef SQLITE_DEBUG
+/*
+** Print a listing of all referenced pages and their ref count.
+*/
+void sqlite3pager_refdump(Pager *pPager){
+ PgHdr *pPg;
+ for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
+ if( pPg->nRef<=0 ) continue;
+ sqlite3DebugPrintf("PAGE %3d addr=%p nRef=%d\n",
+ pPg->pgno, PGHDR_TO_DATA(pPg), pPg->nRef);
+ }
+}
+#endif
+
+#endif /* SQLITE_OMIT_DISKIO */