/*

** 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 file contains C code routines that are called by the SQLite parser

** when syntax rules are reduced.  The routines in this file handle the

** following kinds of SQL syntax:

**

**     CREATE TABLE

**     DROP TABLE

**     CREATE INDEX

**     DROP INDEX

**     creating ID lists

**     BEGIN TRANSACTION

**     COMMIT

**     ROLLBACK

**

** $Id: build.c,v 1.498 2008/10/06 16:18:40 danielk1977 Exp $

*/

#include "sqliteInt.h"

#include <ctype.h>

/*

** This routine is called when a new SQL statement is beginning to

** be parsed.  Initialize the pParse structure as needed.

*/

void sqlite3BeginParse(Parse *pParse, int explainFlag){

  pParse->explain = explainFlag;

  pParse->nVar = 0;

}

#ifndef SQLITE_OMIT_SHARED_CACHE

/*

** The TableLock structure is only used by the sqlite3TableLock() and

** codeTableLocks() functions.

*/

struct TableLock {

  int iDb;             /* The database containing the table to be locked */

  int iTab;            /* The root page of the table to be locked */

  u8 isWriteLock;      /* True for write lock.  False for a read lock */

  const char *zName;   /* Name of the table */

};

/*

** Record the fact that we want to lock a table at run-time.  

**

** The table to be locked has root page iTab and is found in database iDb.

** A read or a write lock can be taken depending on isWritelock.

**

** This routine just records the fact that the lock is desired.  The

** code to make the lock occur is generated by a later call to

** codeTableLocks() which occurs during sqlite3FinishCoding().

*/

void sqlite3TableLock(

  Parse *pParse,     /* Parsing context */

  int iDb,           /* Index of the database containing the table to lock */

  int iTab,          /* Root page number of the table to be locked */

  u8 isWriteLock,    /* True for a write lock */

  const char *zName  /* Name of the table to be locked */

){

  int i;

  int nBytes;

  TableLock *p;

  if( iDb<0 ){

    return;

  }

  for(i=0; i<pParse->nTableLock; i++){

    p = &pParse->aTableLock[i];

    if( p->iDb==iDb && p->iTab==iTab ){

      p->isWriteLock = (p->isWriteLock || isWriteLock);

      return;

    }

  }

  nBytes = sizeof(TableLock) * (pParse->nTableLock+1);

  pParse->aTableLock = 

      sqlite3DbReallocOrFree(pParse->db, pParse->aTableLock, nBytes);

  if( pParse->aTableLock ){

    p = &pParse->aTableLock[pParse->nTableLock++];

    p->iDb = iDb;

    p->iTab = iTab;

    p->isWriteLock = isWriteLock;

    p->zName = zName;

  }else{

    pParse->nTableLock = 0;

    pParse->db->mallocFailed = 1;

  }

}

/*

** Code an OP_TableLock instruction for each table locked by the

** statement (configured by calls to sqlite3TableLock()).

*/

static void codeTableLocks(Parse *pParse){

  int i;

  Vdbe *pVdbe; 

  if( 0==(pVdbe = sqlite3GetVdbe(pParse)) ){

    return;

  }

  for(i=0; i<pParse->nTableLock; i++){

    TableLock *p = &pParse->aTableLock[i];

    int p1 = p->iDb;

    sqlite3VdbeAddOp4(pVdbe, OP_TableLock, p1, p->iTab, p->isWriteLock,

                      p->zName, P4_STATIC);

  }

}

#else

  #define codeTableLocks(x)

#endif

/*

** This routine is called after a single SQL statement has been

** parsed and a VDBE program to execute that statement has been

** prepared.  This routine puts the finishing touches on the

** VDBE program and resets the pParse structure for the next

** parse.

**

** Note that if an error occurred, it might be the case that

** no VDBE code was generated.

*/

void sqlite3FinishCoding(Parse *pParse){

  sqlite3 *db;

  Vdbe *v;

  db = pParse->db;

  if( db->mallocFailed ) return;

  if( pParse->nested ) return;

  if( pParse->nErr ) return;

  /* Begin by generating some termination code at the end of the

  ** vdbe program

  */

  v = sqlite3GetVdbe(pParse);

  if( v ){

    sqlite3VdbeAddOp0(v, OP_Halt);

    /* The cookie mask contains one bit for each database file open.

    ** (Bit 0 is for main, bit 1 is for temp, and so forth.)  Bits are

    ** set for each database that is used.  Generate code to start a

    ** transaction on each used database and to verify the schema cookie

    ** on each used database.

    */

    if( pParse->cookieGoto>0 ){

      u32 mask;

      int iDb;

      sqlite3VdbeJumpHere(v, pParse->cookieGoto-1);

      for(iDb=0, mask=1; iDb<db->nDb; mask<<=1, iDb++){

        if( (mask & pParse->cookieMask)==0 ) continue;

        sqlite3VdbeUsesBtree(v, iDb);

        sqlite3VdbeAddOp2(v,OP_Transaction, iDb, (mask & pParse->writeMask)!=0);

        sqlite3VdbeAddOp2(v,OP_VerifyCookie, iDb, pParse->cookieValue[iDb]);

      }

#ifndef SQLITE_OMIT_VIRTUALTABLE

      {

        int i;

        for(i=0; i<pParse->nVtabLock; i++){

          char *vtab = (char *)pParse->apVtabLock[i]->pVtab;

          sqlite3VdbeAddOp4(v, OP_VBegin, 0, 0, 0, vtab, P4_VTAB);

        }

        pParse->nVtabLock = 0;

      }

#endif

      /* Once all the cookies have been verified and transactions opened, 

      ** obtain the required table-locks. This is a no-op unless the 

      ** shared-cache feature is enabled.

      */

      codeTableLocks(pParse);

      sqlite3VdbeAddOp2(v, OP_Goto, 0, pParse->cookieGoto);

    }

#ifndef SQLITE_OMIT_TRACE

    if( !db->init.busy ){

      /* Change the P4 argument of the first opcode (which will always be

      ** an OP_Trace) to be the complete text of the current SQL statement.

      */

      VdbeOp *pOp = sqlite3VdbeGetOp(v, 0);

      if( pOp && pOp->opcode==OP_Trace ){

        sqlite3VdbeChangeP4(v, 0, pParse->zSql, pParse->zTail-pParse->zSql);

      }

    }

#endif /* SQLITE_OMIT_TRACE */

  }

  /* Get the VDBE program ready for execution

  */

  if( v && pParse->nErr==0 && !db->mallocFailed ){

#ifdef SQLITE_DEBUG

    FILE *trace = (db->flags & SQLITE_VdbeTrace)!=0 ? stdout : 0;

    sqlite3VdbeTrace(v, trace);

#endif

    assert( pParse->disableColCache==0 );  /* Disables and re-enables match */

    sqlite3VdbeMakeReady(v, pParse->nVar, pParse->nMem+3,

                         pParse->nTab+3, pParse->explain);

    pParse->rc = SQLITE_DONE;

    pParse->colNamesSet = 0;

  }else if( pParse->rc==SQLITE_OK ){

    pParse->rc = SQLITE_ERROR;

  }

  pParse->nTab = 0;

  pParse->nMem = 0;

  pParse->nSet = 0;

  pParse->nVar = 0;

  pParse->cookieMask = 0;

  pParse->cookieGoto = 0;

}

/*

** Run the parser and code generator recursively in order to generate

** code for the SQL statement given onto the end of the pParse context

** currently under construction.  When the parser is run recursively

** this way, the final OP_Halt is not appended and other initialization

** and finalization steps are omitted because those are handling by the

** outermost parser.

**

** Not everything is nestable.  This facility is designed to permit

** INSERT, UPDATE, and DELETE operations against SQLITE_MASTER.  Use

** care if you decide to try to use this routine for some other purposes.

*/

void sqlite3NestedParse(Parse *pParse, const char *zFormat, ...){

  va_list ap;

  char *zSql;

  char *zErrMsg = 0;

  sqlite3 *db = pParse->db;

# define SAVE_SZ  (sizeof(Parse) - offsetof(Parse,nVar))

  char saveBuf[SAVE_SZ];

  if( pParse->nErr ) return;

  assert( pParse->nested<10 );  /* Nesting should only be of limited depth */

  va_start(ap, zFormat);

  zSql = sqlite3VMPrintf(db, zFormat, ap);

  va_end(ap);

  if( zSql==0 ){

    return;   /* A malloc must have failed */

  }

  pParse->nested++;

  memcpy(saveBuf, &pParse->nVar, SAVE_SZ);

  memset(&pParse->nVar, 0, SAVE_SZ);

  sqlite3RunParser(pParse, zSql, &zErrMsg);

  sqlite3DbFree(db, zErrMsg);

  sqlite3DbFree(db, zSql);

  memcpy(&pParse->nVar, saveBuf, SAVE_SZ);

  pParse->nested--;

}

/*

** Locate the in-memory structure that describes a particular database

** table given the name of that table and (optionally) the name of the

** database containing the table.  Return NULL if not found.

**

** If zDatabase is 0, all databases are searched for the table and the

** first matching table is returned.  (No checking for duplicate table

** names is done.)  The search order is TEMP first, then MAIN, then any

** auxiliary databases added using the ATTACH command.

**

** See also sqlite3LocateTable().

*/

Table *sqlite3FindTable(sqlite3 *db, const char *zName, const char *zDatabase){

  Table *p = 0;

  int i;

  int nName;

  assert( zName!=0 );

  nName = sqlite3Strlen(db, zName) + 1;

  for(i=OMIT_TEMPDB; i<db->nDb; i++){

    int j = (i<2) ? i^1 : i;   /* Search TEMP before MAIN */

    if( zDatabase!=0 && sqlite3StrICmp(zDatabase, db->aDb[j].zName) ) continue;

    p = sqlite3HashFind(&db->aDb[j].pSchema->tblHash, zName, nName);

    if( p ) break;

  }

  return p;

}

/*

** Locate the in-memory structure that describes a particular database

** table given the name of that table and (optionally) the name of the

** database containing the table.  Return NULL if not found.  Also leave an

** error message in pParse->zErrMsg.

**

** The difference between this routine and sqlite3FindTable() is that this

** routine leaves an error message in pParse->zErrMsg where

** sqlite3FindTable() does not.

*/

Table *sqlite3LocateTable(

  Parse *pParse,         /* context in which to report errors */

  int isView,            /* True if looking for a VIEW rather than a TABLE */

  const char *zName,     /* Name of the table we are looking for */

  const char *zDbase     /* Name of the database.  Might be NULL */

){

  Table *p;

  /* Read the database schema. If an error occurs, leave an error message

  ** and code in pParse and return NULL. */

  if( SQLITE_OK!=sqlite3ReadSchema(pParse) ){

    return 0;

  }

  p = sqlite3FindTable(pParse->db, zName, zDbase);

  if( p==0 ){

    const char *zMsg = isView ? "no such view" : "no such table";

    if( zDbase ){

      sqlite3ErrorMsg(pParse, "%s: %s.%s", zMsg, zDbase, zName);

    }else{

      sqlite3ErrorMsg(pParse, "%s: %s", zMsg, zName);

    }

    pParse->checkSchema = 1;

  }

  return p;

}

/*

** Locate the in-memory structure that describes 

** a particular index given the name of that index

** and the name of the database that contains the index.

** Return NULL if not found.

**

** If zDatabase is 0, all databases are searched for the

** table and the first matching index is returned.  (No checking

** for duplicate index names is done.)  The search order is

** TEMP first, then MAIN, then any auxiliary databases added

** using the ATTACH command.

*/

Index *sqlite3FindIndex(sqlite3 *db, const char *zName, const char *zDb){

  Index *p = 0;

  int i;

  int nName = sqlite3Strlen(db, zName)+1;

  for(i=OMIT_TEMPDB; i<db->nDb; i++){

    int j = (i<2) ? i^1 : i;  /* Search TEMP before MAIN */

    Schema *pSchema = db->aDb[j].pSchema;

    if( zDb && sqlite3StrICmp(zDb, db->aDb[j].zName) ) continue;

    assert( pSchema || (j==1 && !db->aDb[1].pBt) );

    if( pSchema ){

      p = sqlite3HashFind(&pSchema->idxHash, zName, nName);

    }

    if( p ) break;

  }

  return p;

}

/*

** Reclaim the memory used by an index

*/

static void freeIndex(Index *p){

  sqlite3 *db = p->pTable->db;

  sqlite3DbFree(db, p->zColAff);

  sqlite3DbFree(db, p);

}

/*

** Remove the given index from the index hash table, and free

** its memory structures.

**

** The index is removed from the database hash tables but

** it is not unlinked from the Table that it indexes.

** Unlinking from the Table must be done by the calling function.

*/

static void sqliteDeleteIndex(Index *p){

  Index *pOld;

  const char *zName = p->zName;

  pOld = sqlite3HashInsert(&p->pSchema->idxHash, zName, strlen(zName)+1, 0);

  assert( pOld==0 || pOld==p );

  freeIndex(p);

}

/*

** For the index called zIdxName which is found in the database iDb,

** unlike that index from its Table then remove the index from

** the index hash table and free all memory structures associated

** with the index.

*/

void sqlite3UnlinkAndDeleteIndex(sqlite3 *db, int iDb, const char *zIdxName){

  Index *pIndex;

  int len;

  Hash *pHash = &db->aDb[iDb].pSchema->idxHash;

  len = sqlite3Strlen(db, zIdxName);

  pIndex = sqlite3HashInsert(pHash, zIdxName, len+1, 0);

  if( pIndex ){

    if( pIndex->pTable->pIndex==pIndex ){

      pIndex->pTable->pIndex = pIndex->pNext;

    }else{

      Index *p;

      for(p=pIndex->pTable->pIndex; p && p->pNext!=pIndex; p=p->pNext){}

      if( p && p->pNext==pIndex ){

        p->pNext = pIndex->pNext;

      }

    }

    freeIndex(pIndex);

  }

  db->flags |= SQLITE_InternChanges;

}

/*

** Erase all schema information from the in-memory hash tables of

** a single database.  This routine is called to reclaim memory

** before the database closes.  It is also called during a rollback

** if there were schema changes during the transaction or if a

** schema-cookie mismatch occurs.

**

** If iDb<=0 then reset the internal schema tables for all database

** files.  If iDb>=2 then reset the internal schema for only the

** single file indicated.

*/

void sqlite3ResetInternalSchema(sqlite3 *db, int iDb){

  int i, j;

  assert( iDb>=0 && iDb<db->nDb );

  if( iDb==0 ){

    sqlite3BtreeEnterAll(db);

  }

  for(i=iDb; i<db->nDb; i++){

    Db *pDb = &db->aDb[i];

    if( pDb->pSchema ){

      assert(i==1 || (pDb->pBt && sqlite3BtreeHoldsMutex(pDb->pBt)));

      sqlite3SchemaFree(pDb->pSchema);

    }

    if( iDb>0 ) return;

  }

  assert( iDb==0 );

  db->flags &= ~SQLITE_InternChanges;

  sqlite3BtreeLeaveAll(db);

  /* If one or more of the auxiliary database files has been closed,

  ** then remove them from the auxiliary database list.  We take the

  ** opportunity to do this here since we have just deleted all of the

  ** schema hash tables and therefore do not have to make any changes

  ** to any of those tables.

  */

  for(i=0; i<db->nDb; i++){

    struct Db *pDb = &db->aDb[i];

    if( pDb->pBt==0 ){

      if( pDb->pAux && pDb->xFreeAux ) pDb->xFreeAux(pDb->pAux);

      pDb->pAux = 0;

    }

  }

  for(i=j=2; i<db->nDb; i++){

    struct Db *pDb = &db->aDb[i];

    if( pDb->pBt==0 ){

      sqlite3DbFree(db, pDb->zName);

      pDb->zName = 0;

      continue;

    }

    if( j<i ){

      db->aDb[j] = db->aDb[i];

    }

    j++;

  }

  memset(&db->aDb[j], 0, (db->nDb-j)*sizeof(db->aDb[j]));

  db->nDb = j;

  if( db->nDb<=2 && db->aDb!=db->aDbStatic ){

    memcpy(db->aDbStatic, db->aDb, 2*sizeof(db->aDb[0]));

    sqlite3DbFree(db, db->aDb);

    db->aDb = db->aDbStatic;

  }

}

/*

** This routine is called when a commit occurs.

*/

void sqlite3CommitInternalChanges(sqlite3 *db){

  db->flags &= ~SQLITE_InternChanges;

}

/*

** Clear the column names from a table or view.

*/

static void sqliteResetColumnNames(Table *pTable){

  int i;

  Column *pCol;

  sqlite3 *db = pTable->db;

  assert( pTable!=0 );

  if( (pCol = pTable->aCol)!=0 ){

    for(i=0; i<pTable->nCol; i++, pCol++){

      sqlite3DbFree(db, pCol->zName);

      sqlite3ExprDelete(db, pCol->pDflt);

      sqlite3DbFree(db, pCol->zType);

      sqlite3DbFree(db, pCol->zColl);

    }

    sqlite3DbFree(db, pTable->aCol);

  }

  pTable->aCol = 0;

  pTable->nCol = 0;

}

/*

** Remove the memory data structures associated with the given

** Table.  No changes are made to disk by this routine.

**

** This routine just deletes the data structure.  It does not unlink

** the table data structure from the hash table.  Nor does it remove

** foreign keys from the sqlite.aFKey hash table.  But it does destroy

** memory structures of the indices and foreign keys associated with 

** the table.

*/

void sqlite3DeleteTable(Table *pTable){

  Index *pIndex, *pNext;

  FKey *pFKey, *pNextFKey;

  sqlite3 *db;

  if( pTable==0 ) return;

  db = pTable->db;

  /* Do not delete the table until the reference count reaches zero. */

  pTable->nRef--;

  if( pTable->nRef>0 ){

    return;

  }

  assert( pTable->nRef==0 );

  /* Delete all indices associated with this table

  */

  for(pIndex = pTable->pIndex; pIndex; pIndex=pNext){

    pNext = pIndex->pNext;

    assert( pIndex->pSchema==pTable->pSchema );

    sqliteDeleteIndex(pIndex);

  }