SQLite

/*
** 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.
**
*************************************************************************
** $Id: btree.c,v 1.47 2002/02/02 18:49:20 drh Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.

/*
** Everything we need to know about an open database
*/
struct Btree {
  Pager *pPager;        /* The page cache */
  BtCursor *pCursor;    /* A list of all open cursors */
  PageOne *page1;       /* First page of the database */
  u8 inTrans;           /* True if a transaction is in progress */
  u8 inCkpt;            /* True if there is a checkpoint on the transaction */
  Hash locks;           /* Key: root page number.  Data: lock count */
};
typedef Btree Bt;

/*
** A cursor is a pointer to a particular entry in the BTree.
** The entry is identified by its MemPage and the index in

** If there is a transaction in progress, this routine is a no-op.
*/
static void unlockBtreeIfUnused(Btree *pBt){
  if( pBt->inTrans==0 && pBt->pCursor==0 && pBt->page1!=0 ){
    sqlitepager_unref(pBt->page1);
    pBt->page1 = 0;
    pBt->inTrans = 0;
    pBt->inCkpt = 0;
  }
}

/*
** Create a new database by initializing the first two pages of the
** file.
*/

  }
  rc = sqlitepager_write(pBt->page1);
  if( rc==SQLITE_OK ){
    rc = newDatabase(pBt);
  }
  if( rc==SQLITE_OK ){
    pBt->inTrans = 1;
    pBt->inCkpt = 0;
  }else{
    unlockBtreeIfUnused(pBt);
  }
  return rc;
}

/*
** Commit the transaction currently in progress.
**
** This will release the write lock on the database file.  If there
** are no active cursors, it also releases the read lock.
*/
int sqliteBtreeCommit(Btree *pBt){
  int rc;
  if( pBt->inTrans==0 ) return SQLITE_ERROR;
  rc = sqlitepager_commit(pBt->pPager);
  pBt->inTrans = 0;
  pBt->inCkpt = 0;
  unlockBtreeIfUnused(pBt);
  return rc;
}

/*
** Rollback the transaction in progress.  All cursors will be
** invalided by this operation.  Any attempt to use a cursor
** that was open at the beginning of this operation will result
** in an error.
**
** This will release the write lock on the database file.  If there
** are no active cursors, it also releases the read lock.
*/
int sqliteBtreeRollback(Btree *pBt){
  int rc;
  BtCursor *pCur;
  if( pBt->inTrans==0 ) return SQLITE_OK;
  pBt->inTrans = 0;
  pBt->inCkpt = 0;
  for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
    if( pCur->pPage ){
      sqlitepager_unref(pCur->pPage);
      pCur->pPage = 0;
    }
  }
  rc = sqlitepager_rollback(pBt->pPager);
  unlockBtreeIfUnused(pBt);
  return rc;
}

/*
** Set the checkpoint for the current transaction.  The checkpoint serves
** as a sub-transaction that can be rolled back independently of the
** main transaction.  You must start a transaction before starting a
** checkpoint.  The checkpoint is ended automatically if the transaction
** commits or rolls back.
**
** Only one checkpoint may be active at a time.  It is an error to try
** to start a new checkpoint if another checkpoint is already active.
*/
int sqliteBtreeBeginCkpt(Btree *pBt){
  int rc;
  if( !pBt->inTrans || pBt->inCkpt ) return SQLITE_ERROR;
  rc = sqlitepager_ckpt_begin(pBt->pPager);
  pBt->inCkpt = 1;
  return rc;
}


/*
** Commit a checkpoint to transaction currently in progress.  If no
** checkpoint is active, this is a no-op.
*/
int sqliteBtreeCommitCkpt(Btree *pBt){
  int rc;
  if( pBt->inCkpt ){
    rc = sqlitepager_ckpt_commit(pBt->pPager);
  }else{
    rc = SQLITE_OK;
  }
  return rc;
}

/*
** Rollback the checkpoint to the current transaction.  If there
** is no active checkpoint or transaction, this routine is a no-op.
**
** All cursors will be invalided by this operation.  Any attempt
** to use a cursor that was open at the beginning of this operation
** will result in an error.
*/
int sqliteBtreeRollbackCkpt(Btree *pBt){
  int rc;
  BtCursor *pCur;
  if( pBt->inCkpt==0 ) return SQLITE_OK;
  for(pCur=pBt->pCursor; pCur; pCur=pCur->pNext){
    if( pCur->pPage ){
      sqlitepager_unref(pCur->pPage);
      pCur->pPage = 0;
    }
  }
  rc = sqlitepager_ckpt_rollback(pBt->pPager);
  return rc;
}

/*
** Create a new cursor for the BTree whose root is on the page
** iTable.  The act of acquiring a cursor gets a read lock on 
** the database file.
**
** If wrFlag==0, then the cursor can only be used for reading.

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite B-Tree file
** subsystem.  See comments in the source code for a detailed description
** of what each interface routine does.
**
** @(#) $Id: btree.h,v 1.20 2002/02/02 18:49:20 drh Exp $
*/
#ifndef _BTREE_H_
#define _BTREE_H_

typedef struct Btree Btree;
typedef struct BtCursor BtCursor;

int sqliteBtreeOpen(const char *zFilename, int mode, int nPg, Btree **ppBtree);
int sqliteBtreeClose(Btree*);
int sqliteBtreeSetCacheSize(Btree*, int);

int sqliteBtreeBeginTrans(Btree*);
int sqliteBtreeCommit(Btree*);
int sqliteBtreeRollback(Btree*);
int sqliteBtreeBeginCkpt(Btree*);
int sqliteBtreeCommitCkpt(Btree*);
int sqliteBtreeRollbackCkpt(Btree*);

int sqliteBtreeCreateTable(Btree*, int*);
int sqliteBtreeCreateIndex(Btree*, int*);
int sqliteBtreeDropTable(Btree*, int);
int sqliteBtreeClearTable(Btree*, int);

int sqliteBtreeCursor(Btree*, int iTable, int wrFlag, BtCursor **ppCur);

**     COPY
**     VACUUM
**     BEGIN TRANSACTION
**     COMMIT
**     ROLLBACK
**     PRAGMA
**
** $Id: build.c,v 1.71 2002/02/02 18:49:20 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** This routine is called after a single SQL statement has been
** parsed and we want to execute the VDBE code to implement 

        " may not be modified", 0);
    pParse->nErr++;
    goto copy_cleanup;
  }
  v = sqliteGetVdbe(pParse);
  if( v ){
    int openOp;
    sqliteBeginMultiWriteOperation(pParse);
    addr = sqliteVdbeAddOp(v, OP_FileOpen, 0, 0);
    sqliteVdbeChangeP3(v, addr, pFilename->z, pFilename->n);
    sqliteVdbeDequoteP3(v, addr);
    openOp = pTab->isTemp ? OP_OpenWrAux : OP_OpenWrite;
    sqliteVdbeAddOp(v, openOp, 0, pTab->tnum);
    sqliteVdbeChangeP3(v, -1, pTab->zName, P3_STATIC);
    for(i=1, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, i++){

  }
  db->flags &= ~SQLITE_InTrans;
  db->onError = OE_Default;
}

/*
** Generate VDBE code that prepares for doing an operation that
** might change the database.  The operation will be atomic in the
** sense that it will either do its changes completely or not at
** all.  So there is not need to set a checkpoint is a transaction
** is already in effect.
*/
void sqliteBeginWriteOperation(Parse *pParse){
  Vdbe *v;
  v = sqliteGetVdbe(pParse);
  if( v==0 ) return;
  if( (pParse->db->flags & SQLITE_InTrans)==0  ){
    sqliteVdbeAddOp(v, OP_Transaction, 0, 0);
    sqliteVdbeAddOp(v, OP_VerifyCookie, pParse->db->schema_cookie, 0);
    pParse->schemaVerified = 1;
  }
}

/*
** Generate VDBE code that prepares for doing an operation that
** might change the database.  The operation might not be atomic in
** the sense that an error may be discovered and the operation might
** abort after some changes have been made.  If we are in the middle 
** of a transaction, then this sets a checkpoint.  If we are not in
** a transaction, then start a transaction.
*/
void sqliteBeginMultiWriteOperation(Parse *pParse){
  Vdbe *v;
  v = sqliteGetVdbe(pParse);
  if( v==0 ) return;
  if( (pParse->db->flags & SQLITE_InTrans)==0 ){
    sqliteVdbeAddOp(v, OP_Transaction, 0, 0);
    sqliteVdbeAddOp(v, OP_VerifyCookie, pParse->db->schema_cookie, 0);
    pParse->schemaVerified = 1;
  }else{
    sqliteVdbeAddOp(v, OP_Checkpoint, 0, 0);
  }
}

/*
** Generate code that concludes an operation that may have changed
** the database.  This is a companion function to BeginWriteOperation().
** If a transaction was started, then commit it.  If a checkpoint was

**    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 parser
** to handle INSERT statements in SQLite.
**
** $Id: insert.c,v 1.40 2002/02/02 18:49:20 drh Exp $
*/
#include "sqliteInt.h"

/*
** This routine is call to handle SQL of the following forms:
**
**    insert into TABLE (IDLIST) values(EXPRLIST)

    goto insert_cleanup;
  }

  /* Allocate a VDBE
  */
  v = sqliteGetVdbe(pParse);
  if( v==0 ) goto insert_cleanup;
  if( pSelect ){
    sqliteBeginMultiWriteOperation(pParse);
  }else{
    sqliteBeginWriteOperation(pParse);
  }

  /* Figure out how many columns of data are supplied.  If the data
  ** is coming from a SELECT statement, then this step has to generate
  ** all the code to implement the SELECT statement and leave the data
  ** in a temporary table.  If data is coming from an expression list,
  ** then we just have to count the number of expressions.
  */

** 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 1.38 2002/02/02 18:49:20 drh Exp $
*/
#include "sqliteInt.h"
#include "pager.h"
#include "os.h"
#include <assert.h>
#include <string.h>

**                       file at the same time.
**
**   SQLITE_WRITELOCK    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.
**




** The page cache comes up in SQLITE_UNLOCK.  The first time a
** sqlite_page_get() occurs, the state transitions to SQLITE_READLOCK.
** After all pages have been released using sqlite_page_unref(),
** the state transitions back to SQLITE_UNLOCK.  The first time
** that sqlite_page_write() is called, the state transitions to
** SQLITE_WRITELOCK.  (Note that sqlite_page_write() can only be
** called on an outstanding page which means that the pager must
** be in SQLITE_READLOCK before it transitions to SQLITE_WRITELOCK.)
** The sqlite_page_rollback() and sqlite_page_commit() functions 
** transition the state from SQLITE_WRITELOCK back to SQLITE_READLOCK.









*/
#define SQLITE_UNLOCK      0
#define SQLITE_READLOCK    1
#define SQLITE_WRITELOCK   2



/*
** 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.
*/

** write lock and acquires a read lock in its place.  The journal file
** is deleted and closed.
*/
static int pager_unwritelock(Pager *pPager){
  int rc;
  PgHdr *pPg;
  if( pPager->state<SQLITE_WRITELOCK ) return SQLITE_OK;
  sqlitepager_ckpt_commit(pPager);
  sqliteOsClose(&pPager->jfd);
  pPager->journalOpen = 0;
  sqliteOsDelete(pPager->zJournal);
  rc = sqliteOsReadLock(&pPager->fd);
  assert( rc==SQLITE_OK );

  sqliteFree( pPager->aInJournal );
  pPager->aInJournal = 0;
  for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
    pPg->inJournal = 0;
    pPg->dirty = 0;
  }
  pPager->state = SQLITE_READLOCK;
  return rc;
}

/*
** Read a single page from the journal file opened on file descriptor
** jfd.  Playback this one page.
*/
static int pager_playback_one_page(Pager *pPager, OsFile *jfd){
  int rc;
  PgHdr *pPg;              /* An existing page in the cache */
  PageRecord pgRec;

  rc = sqliteOsRead(jfd, &pgRec, sizeof(pgRec));
  if( rc!=SQLITE_OK ) return rc;

  /* Sanity checking on the page */
  if( pgRec.pgno>pPager->dbSize || pgRec.pgno==0 ) return SQLITE_CORRUPT;

  /* Playback the page.  Update the in-memory copy of the page
  ** at the same time, if there is one.

/*
** Playback the checkpoint 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 checkpoint is stored in pPager->ckptSize, not in the
**         journal file itself.
**
**    (2)  In addition to playing back the checkpoint journal, also
**         playback all pages of the transaction journal beginning
**         at offset pPager->ckptJSize.
*/
static int pager_ckpt_playback(Pager *pPager){
  int nRec;                /* Number of Records */
  int i;                   /* Loop counter */
  int rc;

  /* Truncate the database back to its original size.
  */
  rc = sqliteOsTruncate(&pPager->fd, pPager->ckptSize*SQLITE_PAGE_SIZE);
  pPager->dbSize = pPager->ckptSize;

  /* Figure out how many records are in the checkpoint journal.
  */
  assert( pPager->ckptOpen && pPager->journalOpen );
  sqliteOsSeek(&pPager->cpfd, 0);
  rc = sqliteOsFileSize(&pPager->cpfd, &nRec);

  for(i=nRec-1; i>=0; i--){
    rc = pager_playback_one_page(pPager, &pPager->jfd);
    if( rc!=SQLITE_OK ) goto end_ckpt_playback;
  }
  

end_ckpt_playback:


  if( rc!=SQLITE_OK ){

    pPager->errMask |= PAGER_ERR_CORRUPT;
    rc = SQLITE_CORRUPT;


  }
  return rc;
}

/*
** Change the maximum number of in-memory pages that are allowed.
*/

** 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.
*/
int sqlitepager_close(Pager *pPager){
  PgHdr *pPg, *pNext;
  switch( pPager->state ){

    case SQLITE_WRITELOCK: {
      sqlitepager_rollback(pPager);
      sqliteOsUnlock(&pPager->fd);
      assert( pPager->journalOpen==0 );
      break;
    }
    case SQLITE_READLOCK: {

    }
    pPg->pgno = pgno;
    if( pPager->aInJournal && (int)pgno<=pPager->origDbSize ){
      pPg->inJournal = (pPager->aInJournal[pgno/8] & (1<<(pgno&7)))!=0;
    }else{
      pPg->inJournal = 0;
    }
    if( pPager->aInCkpt && (int)pgno<=pPager->ckptSize ){
      pPg->inCkpt = (pPager->aInCkpt[pgno/8] & (1<<(pgno&7)))!=0;
    }else{
      pPg->inCkpt = 0;
    }
    pPg->dirty = 0;
    pPg->nRef = 1;
    REFINFO(pPg);

      pPg->inCkpt = 1;
    }
  }

  /* If the checkpoint journal is open and the page is not in it,
  ** then write the current page to the checkpoint journal.
  */
  if( pPager->ckptOpen && !pPg->inCkpt && (int)pPg->pgno<=pPager->ckptSize ){

    assert( pPg->inJournal );
    rc = sqliteOsWrite(&pPager->cpfd, &pPg->pgno, sizeof(Pgno));
    if( rc==SQLITE_OK ){
      rc = sqliteOsWrite(&pPager->cpfd, pData, SQLITE_PAGE_SIZE);
    }
    if( rc!=SQLITE_OK ){
      sqlitepager_rollback(pPager);

  pPager->aInCkpt = sqliteMalloc( pPager->dbSize/8 + 1 );
  if( pPager->aInCkpt==0 ){
    sqliteOsReadLock(&pPager->fd);
    return SQLITE_NOMEM;
  }
  rc = sqliteOsFileSize(&pPager->jfd, &pPager->ckptJSize);
  if( rc ) goto ckpt_begin_failed;
  pPager->ckptSize = pPager->dbSize;
  rc = sqlitepager_opentemp(zTemp, &pPager->cpfd);
  if( rc ) goto ckpt_begin_failed;
  pPager->ckptOpen = 1;
  return SQLITE_OK;
 
ckpt_begin_failed:
  if( pPager->aInCkpt ){
    sqliteFree(pPager->aInCkpt);
    pPager->aInCkpt = 0;
  }
  return rc;
}

/*
** Commit a checkpoint.
*/
int sqlitepager_ckpt_commit(Pager *pPager){
  if( pPager->ckptOpen ){
    PgHdr *pPg;
    sqliteOsClose(&pPager->cpfd);

    pPager->ckptOpen = 0;
    sqliteFree( pPager->aInCkpt );
    pPager->aInCkpt = 0;
    for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
      pPg->inCkpt = 0;
    }
  }
  return SQLITE_OK;
}

/*
** Rollback a checkpoint.
*/
int sqlitepager_ckpt_rollback(Pager *pPager){
  int rc;
  if( pPager->ckptOpen ){
    rc = pager_ckpt_playback(pPager);
    sqlitepager_ckpt_commit(pPager);
  }else{
    rc = SQLITE_OK;
  }
  return rc;
}

#if SQLITE_TEST
/*
** Print a listing of all referenced pages and their ref count.
*/

/*
** 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.
**
*************************************************************************
** Internal interface definitions for SQLite.
**
** @(#) $Id: sqliteInt.h,v 1.84 2002/02/02 18:49:21 drh Exp $
*/
#include "sqlite.h"
#include "hash.h"
#include "vdbe.h"
#include "parse.h"
#include "btree.h"
#include <stdio.h>

char *sqlite_mprintf(const char *, ...);
int sqliteExprIsConstant(Expr*);
void sqliteGenerateRowDelete(Vdbe*, Table*, int);
void sqliteGenerateRowIndexDelete(Vdbe*, Table*, int, char*);
void sqliteGenerateConstraintChecks(Parse*,Table*,int,char*,int,int,int,int);
void sqliteCompleteInsertion(Parse*, Table*, int, char*, int, int);
void sqliteBeginWriteOperation(Parse*);
void sqliteBeginMultiWriteOperation(Parse*);
void sqliteEndWriteOperation(Parse*);

**    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 parser
** to handle UPDATE statements.
**
** $Id: update.c,v 1.33 2002/02/02 18:49:21 drh Exp $
*/
#include "sqliteInt.h"

/*
** Process an UPDATE statement.
*/
void sqliteUpdate(

    }
  }

  /* Begin generating code.
  */
  v = sqliteGetVdbe(pParse);
  if( v==0 ) goto update_cleanup;
  sqliteBeginMultiWriteOperation(pParse);

  /* Begin the database scan
  */
  pWInfo = sqliteWhereBegin(pParse, pTabList, pWhere, 1);
  if( pWInfo==0 ) goto update_cleanup;

  /* Remember the index of every item to be updated.

** type to the other occurs as necessary.
** 
** Most of the code in this file is taken up by the sqliteVdbeExec()
** function which does the work of interpreting a VDBE program.
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.114 2002/02/02 18:49:21 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

/*
** The following global variable is incremented every time a cursor
** moves, either by the OP_MoveTo or the OP_Next opcode.  The test

**
** If any of the numeric OP_ values for opcodes defined in sqliteVdbe.h
** change, be sure to change this array to match.  You can use the
** "opNames.awk" awk script which is part of the source tree to regenerate
** this array, then copy and paste it into this file, if you want.
*/
static char *zOpName[] = { 0,
  "Transaction",       "Checkpoint",        "Commit",            "Rollback",
  "ReadCookie",        "SetCookie",         "VerifyCookie",      "Open",
  "OpenTemp",          "OpenWrite",         "OpenAux",           "OpenWrAux",
  "Close",             "MoveTo",            "NewRecno",          "PutIntKey",
  "PutStrKey",         "Distinct",          "Found",             "NotFound",
  "IsUnique",          "NotExists",         "Delete",            "Column",
  "KeyAsData",         "Recno",             "FullKey",           "Rewind",
  "Next",              "Destroy",           "Clear",             "CreateIndex",
  "CreateTable",       "Reorganize",        "IdxPut",            "IdxDelete",
  "IdxRecno",          "IdxGT",             "IdxGE",             "MemLoad",
  "MemStore",          "ListWrite",         "ListRewind",        "ListRead",
  "ListReset",         "SortPut",           "SortMakeRec",       "SortMakeKey",
  "Sort",              "SortNext",          "SortCallback",      "SortReset",
  "FileOpen",          "FileRead",          "FileColumn",        "AggReset",
  "AggFocus",          "AggIncr",           "AggNext",           "AggSet",
  "AggGet",            "SetInsert",         "SetFound",          "SetNotFound",
  "MakeRecord",        "MakeKey",           "MakeIdxKey",        "IncrKey",
  "Goto",              "If",                "Halt",              "ColumnCount",
  "ColumnName",        "Callback",          "NullCallback",      "Integer",
  "String",            "Pop",               "Dup",               "Pull",
  "Push",              "MustBeInt",         "Add",               "AddImm",
  "Subtract",          "Multiply",          "Divide",            "Remainder",
  "BitAnd",            "BitOr",             "BitNot",            "ShiftLeft",
  "ShiftRight",        "AbsValue",          "Precision",         "Min",
  "Max",               "Like",              "Glob",              "Eq",
  "Ne",                "Lt",                "Le",                "Gt",
  "Ge",                "IsNull",            "NotNull",           "Negative",
  "And",               "Or",                "Not",               "Concat",
  "Noop",              "Strlen",            "Substr",            "Limit",
};

/*
** Given the name of an opcode, return its number.  Return 0 if
** there is no match.
**
** This routine is used for testing and debugging.

  int pc;                    /* The program counter */
  Op *pOp;                   /* Current operation */
  int rc;                    /* Value to return */
  Btree *pBt = p->pBt;       /* The backend driver */
  sqlite *db = p->db;        /* The database */
  char **zStack;             /* Text stack */
  Stack *aStack;             /* Additional stack information */
  int errorAction = OE_Abort; /* Recovery action to do in case of an error */
  int undoTransOnError = 0;   /* If error, either ROLLBACK or COMMIT */
  char zBuf[100];             /* Space to sprintf() an integer */


  /* No instruction ever pushes more than a single element onto the
  ** stack.  And the stack never grows on successive executions of the
  ** same loop.  So the total number of instructions is an upper bound
  ** on the maximum stack depth required.
  **

** There is an implied "Halt 0 0 0" instruction inserted at the very end of
** every program.  So a jump past the last instruction of the program
** is the same as executing Halt.
*/
case OP_Halt: {
  if( pOp->p1!=SQLITE_OK ){
    rc = pOp->p1;
    errorAction = pOp->p2;
    goto abort_due_to_error;
  }else{
    pc = p->nOp-1;
  }
  break;
}

    memcpy(zNew, zStack[tos], aStack[tos].n);
    zStack[tos] = zNew;
    aStack[tos].flags = STK_Str | STK_Dyn;
  }
  zStack[tos][aStack[tos].n-1]++;
  break;
}

/* Opcode: Checkpoint * * *
**
** Begin a checkpoint.  A checkpoint is the beginning of a operation that
** is part of a larger transaction but which might need to be rolled back
** itself without effecting the containing transaction.  A checkpoint will
** be automatically committed or rollback when the VDBE halts.
*/
case OP_Checkpoint: {
  rc = sqliteBtreeBeginCkpt(pBt);
  if( rc==SQLITE_OK && db->pBeTemp ){
     rc = sqliteBtreeBeginCkpt(pBt);
  }
  break;
}

/* Opcode: Transaction * * *
**
** Begin a transaction.  The transaction ends when a Commit or Rollback
** opcode is encountered.  Depending on the ON CONFLICT setting, the
** transaction might also be rolled back if an error is encountered.
**
** A write lock is obtained on the database file when a transaction is
** started.  No other process can read or write the file while the
** transaction is underway.  Starting a transaction also creates a
** rollback journal.  A transaction must be started before any changes
** can be made to the database.

*/
case OP_Transaction: {
  int busy = 0;
  if( db->pBeTemp ){
    rc = sqliteBtreeBeginTrans(db->pBeTemp);
    if( rc!=SQLITE_OK ){
      goto abort_due_to_error;

        break;
      }
      default: {
        goto abort_due_to_error;
      }
    }
  }while( busy );
  undoTransOnError = 1;
  break;
}

/* Opcode: Commit * * *
**
** Cause all modifications to the database that have been made since the
** last Transaction to actually take effect.  No additional modifications

      fprintf(p->trace,"\n");
    }
#endif
  }

cleanup:
  Cleanup(p);
  if( rc!=SQLITE_OK ){
    switch( errorAction ){
      case OE_Abort: {
        if( !undoTransOnError ){
          sqliteBtreeRollbackCkpt(pBt);
          if( db->pBeTemp ) sqliteBtreeRollbackCkpt(db->pBeTemp);
          break;
        }
        /* Fall through to ROLLBACK */
      }
      case OE_Rollback: {
        sqliteBtreeRollback(pBt);
        if( db->pBeTemp ) sqliteBtreeRollback(db->pBeTemp);
        sqliteRollbackInternalChanges(db);
        db->flags &= ~SQLITE_InTrans;
        db->onError = OE_Default;
        break;
      }
      default: {
        if( undoTransOnError ){
          sqliteBtreeCommit(pBt);
          if( db->pBeTemp ) sqliteBtreeCommit(db->pBeTemp);
          sqliteCommitInternalChanges(db);
          db->flags &= ~SQLITE_InTrans;
          db->onError = OE_Default;
        }
        break;
      }
    }
  }else{
    sqliteBtreeCommitCkpt(pBt);
    if( db->pBeTemp ) sqliteBtreeCommitCkpt(db->pBeTemp);
  }   
  return rc;

  /* Jump to here if a malloc() fails.  It's hard to get a malloc()
  ** to fail on a modern VM computer, so this code is untested.
  */
no_mem:
  sqliteSetString(pzErrMsg, "out of memory", 0);

*************************************************************************
** Header file for the Virtual DataBase Engine (VDBE)
**
** This header defines the interface to the virtual database engine
** or VDBE.  The VDBE implements an abstract machine that runs a
** simple program to access and modify the underlying database.
**
** $Id: vdbe.h,v 1.40 2002/02/02 18:49:21 drh Exp $
*/
#ifndef _SQLITE_VDBE_H_
#define _SQLITE_VDBE_H_
#include <stdio.h>

/*
** A single VDBE is an opaque structure named "Vdbe".  Only routines

** be sure to also update the zOpName[] array in sqliteVdbe.c to
** mirror the change.
**
** The source tree contains an AWK script named renumberOps.awk that
** can be used to renumber these opcodes when new opcodes are inserted.
*/
#define OP_Transaction         1
#define OP_Checkpoint          2
#define OP_Commit              3
#define OP_Rollback            4

#define OP_ReadCookie          5
#define OP_SetCookie           6
#define OP_VerifyCookie        7

#define OP_Open                8
#define OP_OpenTemp            9
#define OP_OpenWrite          10
#define OP_OpenAux            11
#define OP_OpenWrAux          12
#define OP_Close              13
#define OP_MoveTo             14
#define OP_NewRecno           15
#define OP_PutIntKey          16
#define OP_PutStrKey          17
#define OP_Distinct           18
#define OP_Found              19
#define OP_NotFound           20
#define OP_IsUnique           21
#define OP_NotExists          22
#define OP_Delete             23
#define OP_Column             24
#define OP_KeyAsData          25
#define OP_Recno              26
#define OP_FullKey            27
#define OP_Rewind             28
#define OP_Next               29

#define OP_Destroy            30
#define OP_Clear              31
#define OP_CreateIndex        32
#define OP_CreateTable        33
#define OP_Reorganize         34

#define OP_IdxPut             35
#define OP_IdxDelete          36
#define OP_IdxRecno           37
#define OP_IdxGT              38
#define OP_IdxGE              39

#define OP_MemLoad            40
#define OP_MemStore           41

#define OP_ListWrite          42
#define OP_ListRewind         43
#define OP_ListRead           44
#define OP_ListReset          45

#define OP_SortPut            46
#define OP_SortMakeRec        47
#define OP_SortMakeKey        48
#define OP_Sort               49
#define OP_SortNext           50
#define OP_SortCallback       51
#define OP_SortReset          52

#define OP_FileOpen           53
#define OP_FileRead           54
#define OP_FileColumn         55

#define OP_AggReset           56
#define OP_AggFocus           57
#define OP_AggIncr            58
#define OP_AggNext            59
#define OP_AggSet             60
#define OP_AggGet             61

#define OP_SetInsert          62
#define OP_SetFound           63
#define OP_SetNotFound        64

#define OP_MakeRecord         65
#define OP_MakeKey            66
#define OP_MakeIdxKey         67
#define OP_IncrKey            68

#define OP_Goto               69
#define OP_If                 70
#define OP_Halt               71

#define OP_ColumnCount        72
#define OP_ColumnName         73
#define OP_Callback           74
#define OP_NullCallback       75

#define OP_Integer            76
#define OP_String             77
#define OP_Pop                78
#define OP_Dup                79
#define OP_Pull               80
#define OP_Push               81
#define OP_MustBeInt          82

#define OP_Add                83
#define OP_AddImm             84
#define OP_Subtract           85
#define OP_Multiply           86
#define OP_Divide             87
#define OP_Remainder          88
#define OP_BitAnd             89
#define OP_BitOr              90
#define OP_BitNot             91
#define OP_ShiftLeft          92
#define OP_ShiftRight         93
#define OP_AbsValue           94
#define OP_Precision          95
#define OP_Min                96
#define OP_Max                97
#define OP_Like               98
#define OP_Glob               99
#define OP_Eq                100
#define OP_Ne                101
#define OP_Lt                102
#define OP_Le                103
#define OP_Gt                104
#define OP_Ge                105
#define OP_IsNull            106
#define OP_NotNull           107
#define OP_Negative          108
#define OP_And               109
#define OP_Or                110
#define OP_Not               111
#define OP_Concat            112
#define OP_Noop              113

#define OP_Strlen            114
#define OP_Substr            115

#define OP_Limit             116

#define OP_MAX               116

/*
** Prototypes for the VDBE interface.  See comments on the implementation
** for a description of what each of these routines does.
*/
Vdbe *sqliteVdbeCreate(sqlite*);
void sqliteVdbeCreateCallback(Vdbe*, int*);

# 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 implements regression tests for SQLite library.  The
# focus of this script is page cache subsystem.
#
# $Id: pager.test,v 1.11 2002/02/02 18:49:21 drh Exp $


set testdir [file dirname $argv0]
source $testdir/tester.tcl

if {[info commands pager_open]!=""} {

  } $i body;
  do_test pager-3.7.$i.3 $body {1}
}
do_test pager-3.99 {
  pager_close $::p1
} {}

# tests of the checkpoint mechanism and api
#
do_test pager-4.0 {
  set v [catch {
    file delete -force ptf1.db
    set ::p1 [pager_open ptf1.db 15]
  } msg]
  if {$v} {lappend v $msg}
  set v
} {0}
do_test pager-4.1 {
  set g1 [page_get $::p1 1]
  page_write $g1 "Page-1 v0"
  for {set i 2} {$i<=20} {incr i} {
    set gx [page_get $::p1 $i]
    page_write $gx "Page-$i v0"
    page_unref $gx
  }
  pager_commit $::p1
} {}
for {set i 1} {$i<=20} {incr i} {
  do_test pager-4.2.$i {
    set gx [page_get $p1 $i]
    set v [page_read $gx]
    page_unref $gx
    set v
  } "Page-$i v0"
}
do_test pager-4.3 {
  lrange [pager_stats $::p1] 0 1
} {ref 1}
do_test pager-4.4 {
  lrange [pager_stats $::p1] 8 9
} {state 1}

for {set i 1} {$i<20} {incr i} {
  do_test pager-4.5.$i.0 {
    set res {}
    for {set j 2} {$j<=20} {incr j} {
      set gx [page_get $p1 $j]
      set value [page_read $gx]
      page_unref $gx
      set shouldbe "Page-$j v[expr {$i-1}]"
      if {$value!=$shouldbe} {
        lappend res $value $shouldbe
      }
    }
    set res
  } {}
  do_test pager-4.5.$i.1 {
    page_write $g1 "Page-1 v$i"
    lrange [pager_stats $p1] 8 9
  } {state 2}
  do_test pager-4.5.$i.2 {
    for {set j 2} {$j<=20} {incr j} {
      set gx [page_get $p1 $j]
      page_write $gx "Page-$j v$i"
      page_unref $gx
      if {$j==$i} {
        pager_ckpt_begin $p1
      }
    }
  } {}
  do_test pager-4.5.$i.3 {
    set res {}
    for {set j 2} {$j<=20} {incr j} {
      set gx [page_get $p1 $j]
      set value [page_read $gx]
      page_unref $gx
      set shouldbe "Page-$j v$i"
      if {$value!=$shouldbe} {
        lappend res $value $shouldbe
      }
    }
    set res
  } {}
  do_test pager-4.5.$i.4 {
    pager_rollback $p1
    set res {}
    for {set j 2} {$j<=20} {incr j} {
      set gx [page_get $p1 $j]
      set value [page_read $gx]
      page_unref $gx
      set shouldbe "Page-$j v[expr {$i-1}]"
      if {$value!=$shouldbe} {
        lappend res $value $shouldbe
      }
    }
    set res
  } {}
  do_test pager-4.5.$i.5 {
    page_write $g1 "Page-1 v$i"
    lrange [pager_stats $p1] 8 9
  } {state 2}
  do_test pager-4.5.$i.6 {
    for {set j 2} {$j<=20} {incr j} {
      set gx [page_get $p1 $j]
      page_write $gx "Page-$j v$i"
      page_unref $gx
      if {$j==$i} {
        pager_ckpt_begin $p1
      }
    }
  } {}
  do_test pager-4.5.$i.7 {
    pager_ckpt_rollback $p1
    for {set j 2} {$j<=20} {incr j} {
      set gx [page_get $p1 $j]
      set value [page_read $gx]
      page_unref $gx
      if {$j<=$i || $i==1} {
        set shouldbe "Page-$j v$i"
      } else {
        set shouldbe "Page-$j v[expr {$i-1}]"
      }
      if {$value!=$shouldbe} {
        lappend res $value $shouldbe
      }
    }
    set res
  } {}
  do_test pager-4.5.$i.8 {
    for {set j 2} {$j<=20} {incr j} {
      set gx [page_get $p1 $j]
      page_write $gx "Page-$j v$i"
      page_unref $gx
      if {$j==$i} {
        pager_ckpt_begin $p1
      }
    }
  } {}
  do_test pager-4.5.$i.9 {
    pager_ckpt_commit $p1
    for {set j 2} {$j<=20} {incr j} {
      set gx [page_get $p1 $j]
      set value [page_read $gx]
      page_unref $gx
      set shouldbe "Page-$j v$i"
      if {$value!=$shouldbe} {
        lappend res $value $shouldbe
      }
    }
    set res
  } {}
  do_test pager-4.5.$i.10 {
    pager_commit $p1
    lrange [pager_stats $p1] 8 9
  } {state 1}
}

do_test pager-4.99 {
  pager_close $::p1
} {}



  file delete -force ptf1.db

} ;# end if( not mem: and has pager_open command );

finish_test