SQLite

** This file contains the C functions that implement various SQL
** functions of SQLite.  
**
** There is only one exported symbol in this file - the function
** sqliteRegisterBuildinFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: func.c,v 1.237 2009/06/03 01:24:54 drh Exp $
*/
#include "sqliteInt.h"
#include <stdlib.h>
#include <assert.h>
#include "vdbeInt.h"

/*

  if( !db->mallocFailed ){
    int rc = sqlite3_overload_function(db, "MATCH", 2);
    assert( rc==SQLITE_NOMEM || rc==SQLITE_OK );
    if( rc==SQLITE_NOMEM ){
      db->mallocFailed = 1;
    }
  }
#ifdef SQLITE_SSE
  (void)sqlite3SseFunctions(db);
#endif
}

/*
** Set the LIKEOPT flag on the 2-argument function with the given name.
*/
static void setLikeOptFlag(sqlite3 *db, const char *zName, u8 flagVal){
  FuncDef *pDef;

**
*************************************************************************
** Main file for the SQLite library.  The routines in this file
** implement the programmer interface to the library.  Routines in
** other files are for internal use by SQLite and should not be
** accessed by users of the library.
**
** $Id: main.c,v 1.557 2009/06/09 19:53:58 drh Exp $
*/
#include "sqliteInt.h"

#ifdef SQLITE_ENABLE_FTS3
# include "fts3.h"
#endif
#ifdef SQLITE_ENABLE_RTREE

    return SQLITE_OK;
  }
  if( !sqlite3SafetyCheckSickOrOk(db) ){
    return SQLITE_MISUSE;
  }
  sqlite3_mutex_enter(db->mutex);

#ifdef SQLITE_SSE
  {
    extern void sqlite3SseCleanup(sqlite3*);
    sqlite3SseCleanup(db);
  }
#endif 

  sqlite3ResetInternalSchema(db, 0);

  /* If a transaction is open, the ResetInternalSchema() call above
  ** will not have called the xDisconnect() method on any virtual
  ** tables in the db->aVTrans[] array. The following sqlite3VtabRollback()
  ** call will do so. We need to do this before the check for active
  ** SQL statements below, as the v-table implementation may be storing

**
*************************************************************************
** This file contains SQLite's grammar for SQL.  Process this file
** using the lemon parser generator to generate C code that runs
** the parser.  Lemon will also generate a header file containing
** numeric codes for all of the tokens.
**
** @(#) $Id: parse.y,v 1.282 2009/06/12 13:53:52 drh Exp $
*/

// All token codes are small integers with #defines that begin with "TK_"
%token_prefix TK_

// The type of the data attached to each token is Token.  This is also the
// default type for non-terminals.

cmd ::= VACUUM.                {sqlite3Vacuum(pParse);}
cmd ::= VACUUM nm.             {sqlite3Vacuum(pParse);}
%endif  SQLITE_OMIT_ATTACH
%endif  SQLITE_OMIT_VACUUM

///////////////////////////// The PRAGMA command /////////////////////////////
//
%ifndef SQLITE_OMIT_PARSER
%ifndef SQLITE_OMIT_PRAGMA
cmd ::= PRAGMA nm(X) dbnm(Z).                {sqlite3Pragma(pParse,&X,&Z,0,0);}
cmd ::= PRAGMA nm(X) dbnm(Z) EQ nmnum(Y).    {sqlite3Pragma(pParse,&X,&Z,&Y,0);}
cmd ::= PRAGMA nm(X) dbnm(Z) LP nmnum(Y) RP. {sqlite3Pragma(pParse,&X,&Z,&Y,0);}
cmd ::= PRAGMA nm(X) dbnm(Z) EQ minus_num(Y). 
                                             {sqlite3Pragma(pParse,&X,&Z,&Y,1);}
cmd ::= PRAGMA nm(X) dbnm(Z) LP minus_num(Y) RP.
                                             {sqlite3Pragma(pParse,&X,&Z,&Y,1);}

nmnum(A) ::= plus_num(X).             {A = X;}
nmnum(A) ::= nm(X).                   {A = X;}
nmnum(A) ::= ON(X).                   {A = X;}
nmnum(A) ::= DELETE(X).               {A = X;}
nmnum(A) ::= DEFAULT(X).              {A = X;}
%endif SQLITE_OMIT_PRAGMA
%endif SQLITE_OMIT_PARSER
plus_num(A) ::= plus_opt number(X).   {A = X;}
minus_num(A) ::= MINUS number(X).     {A = X;}
number(A) ::= INTEGER|FLOAT(X).       {A = X;}
plus_opt ::= PLUS.
plus_opt ::= .

//////////////////////////// The CREATE TRIGGER command /////////////////////

/*
** 2003 April 6
**
** 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 code used to implement the PRAGMA command.
**
** $Id: pragma.c,v 1.212 2009/06/03 11:25:07 danielk1977 Exp $
*/
#include "sqliteInt.h"

/* Ignore this whole file if pragmas are disabled
*/
#if !defined(SQLITE_OMIT_PRAGMA) && !defined(SQLITE_OMIT_PARSER)

/*
** Interpret the given string as a safety level.  Return 0 for OFF,
** 1 for ON or NORMAL and 2 for FULL.  Return 1 for an empty or 
** unrecognized string argument.
**
** Note that the values returned are one less that the values that

      sqlite3VdbeAddOp4(v, OP_String8, 0, 2, 0, zState, P4_STATIC);
      sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 2);
    }

  }else
#endif

#ifdef SQLITE_SSE
  /*
  ** Check to see if the sqlite_statements table exists.  Create it
  ** if it does not.
  */
  if( sqlite3StrICmp(zLeft, "create_sqlite_statement_table")==0 ){
    extern int sqlite3CreateStatementsTable(Parse*);
    sqlite3CreateStatementsTable(pParse);
  }else
#endif

#if SQLITE_HAS_CODEC
  if( sqlite3StrICmp(zLeft, "key")==0 && zRight ){
    sqlite3_key(db, zRight, sqlite3Strlen30(zRight));
  }else
  if( sqlite3StrICmp(zLeft, "rekey")==0 && zRight ){
    sqlite3_rekey(db, zRight, sqlite3Strlen30(zRight));
  }else

  }
#endif
pragma_out:
  sqlite3DbFree(db, zLeft);
  sqlite3DbFree(db, zRight);
}

#endif /* SQLITE_OMIT_PRAGMA || SQLITE_OMIT_PARSER */

/*
** 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 1.885 2009/06/18 17:22:39 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** Include the configuration header output by 'configure' if we're using the
** autoconf-based build

  int nVTrans;                  /* Allocated size of aVTrans */
#endif
  FuncDefHash aFunc;            /* Hash table of connection functions */
  Hash aCollSeq;                /* All collating sequences */
  BusyHandler busyHandler;      /* Busy callback */
  int busyTimeout;              /* Busy handler timeout, in msec */
  Db aDbStatic[2];              /* Static space for the 2 default backends */
#ifdef SQLITE_SSE
  sqlite3_stmt *pFetch;         /* Used by SSE to fetch stored statements */
#endif
  Savepoint *pSavepoint;        /* List of active savepoints */
  int nSavepoint;               /* Number of non-transaction savepoints */
  int nStatement;               /* Number of nested statement-transactions  */
  u8 isTransactionSavepoint;    /* True if the outermost savepoint is a TS */

#ifdef SQLITE_ENABLE_UNLOCK_NOTIFY
  /* The following variables are all protected by the STATIC_MASTER 

  void sqlite3ConnectionClosed(sqlite3 *db);
#else
  #define sqlite3ConnectionBlocked(x,y)
  #define sqlite3ConnectionUnlocked(x)
  #define sqlite3ConnectionClosed(x)
#endif


#ifdef SQLITE_SSE
#include "sseInt.h"
#endif

#ifdef SQLITE_DEBUG
  void sqlite3ParserTrace(FILE*, char *);
#endif

/*
** If the SQLITE_ENABLE IOTRACE exists then the global variable
** sqlite3IoTrace is a pointer to a printf-like routine used to

** 
** This file contains code used for testing the SQLite system.
** None of the code in this file goes into a deliverable build.
** 
** The focus of this file is providing the TCL testing layer
** access to compile-time constants.
**
** $Id: test_config.c,v 1.49 2009/06/09 13:42:25 drh Exp $
*/

#include "sqliteLimit.h"

#include "sqliteInt.h"
#include "tcl.h"
#include <stdlib.h>

#ifdef SQLITE_OMIT_PAGER_PRAGMAS
  Tcl_SetVar2(interp, "sqlite_options", "pager_pragmas", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "pager_pragmas", "1", TCL_GLOBAL_ONLY);
#endif

#ifdef SQLITE_OMIT_PARSER
  Tcl_SetVar2(interp, "sqlite_options", "parser", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "parser", "1", TCL_GLOBAL_ONLY);
#endif

#if defined(SQLITE_OMIT_PRAGMA) || defined(SQLITE_OMIT_FLAG_PRAGMAS)
  Tcl_SetVar2(interp, "sqlite_options", "pragma", "0", TCL_GLOBAL_ONLY);
  Tcl_SetVar2(interp, "sqlite_options", "integrityck", "0", TCL_GLOBAL_ONLY);
#else
  Tcl_SetVar2(interp, "sqlite_options", "pragma", "1", TCL_GLOBAL_ONLY);
#endif

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.855 2009/06/18 00:41:56 drh Exp $
*/
#include "sqliteInt.h"
#include "vdbeInt.h"

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

  sqlite3BtreeLeaveAll(db);
  if( rc==SQLITE_NOMEM ){
    goto no_mem;
  }
  break;  
}

#if !defined(SQLITE_OMIT_ANALYZE) && !defined(SQLITE_OMIT_PARSER)
/* Opcode: LoadAnalysis P1 * * * *
**
** Read the sqlite_stat1 table for database P1 and load the content
** of that table into the internal index hash table.  This will cause
** the analysis to be used when preparing all subsequent queries.
*/
case OP_LoadAnalysis: {
  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  rc = sqlite3AnalysisLoad(db, pOp->p1);
  break;  
}
#endif /* !defined(SQLITE_OMIT_ANALYZE) && !defined(SQLITE_OMIT_PARSER)  */

/* Opcode: DropTable P1 * * P4 *
**
** Remove the internal (in-memory) data structures that describe
** the table named P4 in database P1.  This is called after a table
** is dropped in order to keep the internal representation of the
** schema consistent with what is on disk.

*************************************************************************
** This is the header file for information that is private to the
** VDBE.  This information used to all be at the top of the single
** source code file "vdbe.c".  When that file became too big (over
** 6000 lines long) it was split up into several smaller files and
** this header information was factored out.
**
** $Id: vdbeInt.h,v 1.171 2009/06/05 14:17:25 drh Exp $
*/
#ifndef _VDBEINT_H_
#define _VDBEINT_H_

/*
** intToKey() and keyToInt() used to transform the rowid.  But with
** the latest versions of the design they are no-ops.

** set to 2 for xDestroy method calls and 1 for all other methods. This
** variable is used for two purposes: to allow xDestroy methods to execute
** "DROP TABLE" statements and to prevent some nasty side effects of
** malloc failure when SQLite is invoked recursively by a virtual table 
** method function.
*/
struct Vdbe {
  sqlite3 *db;        /* The whole database */
  Vdbe *pPrev,*pNext; /* Linked list of VDBEs with the same Vdbe.db */
  int nOp;            /* Number of instructions in the program */
  int nOpAlloc;       /* Number of slots allocated for aOp[] */
  Op *aOp;            /* Space to hold the virtual machine's program */
  int nLabel;         /* Number of labels used */
  int nLabelAlloc;    /* Number of slots allocated in aLabel[] */
  int *aLabel;        /* Space to hold the labels */
  Mem **apArg;        /* Arguments to currently executing user function */
  Mem *aColName;      /* Column names to return */


  int nCursor;        /* Number of slots in apCsr[] */
  VdbeCursor **apCsr; /* One element of this array for each open cursor */


  int nVar;           /* Number of entries in aVar[] */
  Mem *aVar;          /* Values for the OP_Variable opcode. */
  char **azVar;       /* Name of variables */
  int okVar;          /* True if azVar[] has been initialized */
  u32 magic;              /* Magic number for sanity checking */
  int nMem;               /* Number of memory locations currently allocated */
  Mem *aMem;              /* The memory locations */
  int cacheCtr;           /* VdbeCursor row cache generation counter */
  int contextStackTop;    /* Index of top element in the context stack */
  int contextStackDepth;  /* The size of the "context" stack */
  Context *contextStack;  /* Stack used by opcodes ContextPush & ContextPop*/
  int pc;                 /* The program counter */
  int rc;                 /* Value to return */
  int errorAction;        /* Recovery action to do in case of an error */
  int nResColumn;         /* Number of columns in one row of the result set */
  char **azResColumn;     /* Values for one row of result */ 
  char *zErrMsg;          /* Error message written here */
  Mem *pResultSet;        /* Pointer to an array of results */
  u8 explain;             /* True if EXPLAIN present on SQL command */
  u8 changeCntOn;         /* True to update the change-counter */
  u8 expired;             /* True if the VM needs to be recompiled */
  u8 minWriteFileFormat;  /* Minimum file format for writable database files */
  u8 inVtabMethod;        /* See comments above */
  u8 usesStmtJournal;     /* True if uses a statement journal */
  u8 readOnly;            /* True for read-only statements */
  u8 isPrepareV2;         /* True if prepared with prepare_v2() */
  int nChange;            /* Number of db changes made since last reset */
  i64 startTime;          /* Time when query started - used for profiling */
  int btreeMask;          /* Bitmask of db->aDb[] entries referenced */

  BtreeMutexArray aMutex; /* An array of Btree used here and needing locks */
  int aCounter[2];        /* Counters used by sqlite3_stmt_status() */
  char *zSql;           /* Text of the SQL statement that generated this */
  void *pFree;            /* Free this when deleting the vdbe */
#ifdef SQLITE_DEBUG
  FILE *trace;          /* Write an execution trace here, if not NULL */
#endif
  int iStatement;         /* Statement number (or 0 if has not opened stmt) */
#ifdef SQLITE_SSE
  int fetchId;          /* Statement number used by sqlite3_fetch_statement */
  int lru;              /* Counter used for LRU cache replacement */
#endif
#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
  Vdbe *pLruPrev;
  Vdbe *pLruNext;
#endif
};

/*
** The following are allowed values for Vdbe.magic
*/
#define VDBE_MAGIC_INIT     0x26bceaa5    /* Building a VDBE program */

**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file contains code use to implement APIs that are part of the
** VDBE.
**
** $Id: vdbeapi.c,v 1.165 2009/06/06 14:13:27 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "vdbeInt.h"

#if 0 && defined(SQLITE_ENABLE_MEMORY_MANAGEMENT)
/*
** The following structure contains pointers to the end points of a
** doubly-linked list of all compiled SQL statements that may be holding
** buffers eligible for release when the sqlite3_release_memory() interface is
** invoked. Access to this list is protected by the SQLITE_MUTEX_STATIC_LRU2
** mutex.
**
** Statements are added to the end of this list when sqlite3_reset() is
** called. They are removed either when sqlite3_step() or sqlite3_finalize()
** is called. When statements are added to this list, the associated 
** register array (p->aMem[1..p->nMem]) may contain dynamic buffers that
** can be freed using sqlite3VdbeReleaseMemory().
**
** When statements are added or removed from this list, the mutex
** associated with the Vdbe being added or removed (Vdbe.db->mutex) is
** already held. The LRU2 mutex is then obtained, blocking if necessary,
** the linked-list pointers manipulated and the LRU2 mutex relinquished.
*/
struct StatementLruList {
  Vdbe *pFirst;
  Vdbe *pLast;
};
static struct StatementLruList sqlite3LruStatements;

/*
** Check that the list looks to be internally consistent. This is used
** as part of an assert() statement as follows:
**
**   assert( stmtLruCheck() );
*/
#ifndef NDEBUG
static int stmtLruCheck(){
  Vdbe *p;
  for(p=sqlite3LruStatements.pFirst; p; p=p->pLruNext){
    assert(p->pLruNext || p==sqlite3LruStatements.pLast);
    assert(!p->pLruNext || p->pLruNext->pLruPrev==p);
    assert(p->pLruPrev || p==sqlite3LruStatements.pFirst);
    assert(!p->pLruPrev || p->pLruPrev->pLruNext==p);
  }
  return 1;
}
#endif

/*
** Add vdbe p to the end of the statement lru list. It is assumed that
** p is not already part of the list when this is called. The lru list
** is protected by the SQLITE_MUTEX_STATIC_LRU mutex.
*/
static void stmtLruAdd(Vdbe *p){
  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU2));

  if( p->pLruPrev || p->pLruNext || sqlite3LruStatements.pFirst==p ){
    sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU2));
    return;
  }

  assert( stmtLruCheck() );

  if( !sqlite3LruStatements.pFirst ){
    assert( !sqlite3LruStatements.pLast );
    sqlite3LruStatements.pFirst = p;
    sqlite3LruStatements.pLast = p;
  }else{
    assert( !sqlite3LruStatements.pLast->pLruNext );
    p->pLruPrev = sqlite3LruStatements.pLast;
    sqlite3LruStatements.pLast->pLruNext = p;
    sqlite3LruStatements.pLast = p;
  }

  assert( stmtLruCheck() );

  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU2));
}

/*
** Assuming the SQLITE_MUTEX_STATIC_LRU2 mutext is already held, remove
** statement p from the least-recently-used statement list. If the 
** statement is not currently part of the list, this call is a no-op.
*/
static void stmtLruRemoveNomutex(Vdbe *p){
  if( p->pLruPrev || p->pLruNext || p==sqlite3LruStatements.pFirst ){
    assert( stmtLruCheck() );
    if( p->pLruNext ){
      p->pLruNext->pLruPrev = p->pLruPrev;
    }else{
      sqlite3LruStatements.pLast = p->pLruPrev;
    }
    if( p->pLruPrev ){
      p->pLruPrev->pLruNext = p->pLruNext;
    }else{
      sqlite3LruStatements.pFirst = p->pLruNext;
    }
    p->pLruNext = 0;
    p->pLruPrev = 0;
    assert( stmtLruCheck() );
  }
}

/*
** Assuming the SQLITE_MUTEX_STATIC_LRU2 mutext is not held, remove
** statement p from the least-recently-used statement list. If the 
** statement is not currently part of the list, this call is a no-op.
*/
static void stmtLruRemove(Vdbe *p){
  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU2));
  stmtLruRemoveNomutex(p);
  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU2));
}

/*
** Try to release n bytes of memory by freeing buffers associated 
** with the memory registers of currently unused vdbes.
*/
int sqlite3VdbeReleaseMemory(int n){
  Vdbe *p;
  Vdbe *pNext;
  int nFree = 0;

  sqlite3_mutex_enter(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU2));
  for(p=sqlite3LruStatements.pFirst; p && nFree<n; p=pNext){
    pNext = p->pLruNext;

    /* For each statement handle in the lru list, attempt to obtain the
    ** associated database mutex. If it cannot be obtained, continue
    ** to the next statement handle. It is not possible to block on
    ** the database mutex - that could cause deadlock.
    */
    if( SQLITE_OK==sqlite3_mutex_try(p->db->mutex) ){
      nFree += sqlite3VdbeReleaseBuffers(p);
      stmtLruRemoveNomutex(p);
      sqlite3_mutex_leave(p->db->mutex);
    }
  }
  sqlite3_mutex_leave(sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_LRU2));

  return nFree;
}

/*
** Call sqlite3Reprepare() on the statement. Remove it from the
** lru list before doing so, as Reprepare() will free all the
** memory register buffers anyway.
*/
int vdbeReprepare(Vdbe *p){
  stmtLruRemove(p);
  return sqlite3Reprepare(p);
}

#else       /* !SQLITE_ENABLE_MEMORY_MANAGEMENT */
  #define stmtLruRemove(x)
  #define stmtLruAdd(x)
  #define vdbeReprepare(x) sqlite3Reprepare(x)
#endif


#ifndef SQLITE_OMIT_DEPRECATED
/*
** Return TRUE (non-zero) of the statement supplied as an argument needs
** to be recompiled.  A statement needs to be recompiled whenever the
** execution environment changes in a way that would alter the program
** that sqlite3_prepare() generates.  For example, if new functions or

  }else{
    Vdbe *v = (Vdbe*)pStmt;
    sqlite3 *db = v->db;
#if SQLITE_THREADSAFE
    sqlite3_mutex *mutex = v->db->mutex;
#endif
    sqlite3_mutex_enter(mutex);
    stmtLruRemove(v);
    rc = sqlite3VdbeFinalize(v);
    rc = sqlite3ApiExit(db, rc);
    sqlite3_mutex_leave(mutex);
  }
  return rc;
}

  int rc;
  if( pStmt==0 ){
    rc = SQLITE_OK;
  }else{
    Vdbe *v = (Vdbe*)pStmt;
    sqlite3_mutex_enter(v->db->mutex);
    rc = sqlite3VdbeReset(v);
    stmtLruAdd(v);
    sqlite3VdbeMakeReady(v, -1, 0, 0, 0);
    assert( (rc & (v->db->errMask))==rc );
    rc = sqlite3ApiExit(v->db, rc);
    sqlite3_mutex_leave(v->db->mutex);
  }
  return rc;
}

      p->startTime = (u64)((rNow - (int)rNow)*3600.0*24.0*1000000000.0);
    }
#endif

    db->activeVdbeCnt++;
    if( p->readOnly==0 ) db->writeVdbeCnt++;
    p->pc = 0;
    stmtLruRemove(p);
  }
#ifndef SQLITE_OMIT_EXPLAIN
  if( p->explain ){
    rc = sqlite3VdbeList(p);
  }else
#endif /* SQLITE_OMIT_EXPLAIN */
  {

}

/*
** This is the top-level implementation of sqlite3_step().  Call
** sqlite3Step() to do most of the work.  If a schema error occurs,
** call sqlite3Reprepare() and try again.
*/
#ifdef SQLITE_OMIT_PARSER
int sqlite3_step(sqlite3_stmt *pStmt){
  int rc = SQLITE_MISUSE;
  if( pStmt ){
    Vdbe *v;
    v = (Vdbe*)pStmt;
    sqlite3_mutex_enter(v->db->mutex);
    rc = sqlite3Step(v);
    sqlite3_mutex_leave(v->db->mutex);
  }
  return rc;
}
#else
int sqlite3_step(sqlite3_stmt *pStmt){
  int rc = SQLITE_MISUSE;
  if( pStmt ){
    int cnt = 0;
    Vdbe *v = (Vdbe*)pStmt;
    sqlite3 *db = v->db;
    sqlite3_mutex_enter(db->mutex);
    while( (rc = sqlite3Step(v))==SQLITE_SCHEMA
           && cnt++ < 5
           && (rc = vdbeReprepare(v))==SQLITE_OK ){
      sqlite3_reset(pStmt);
      v->expired = 0;
    }
    if( rc==SQLITE_SCHEMA && ALWAYS(v->isPrepareV2) && ALWAYS(db->pErr) ){
      /* This case occurs after failing to recompile an sql statement. 
      ** The error message from the SQL compiler has already been loaded 
      ** into the database handle. This block copies the error message 

      }
    }
    rc = sqlite3ApiExit(db, rc);
    sqlite3_mutex_leave(db->mutex);
  }
  return rc;
}
#endif

/*
** Extract the user data from a sqlite3_context structure and return a
** pointer to it.
*/
void *sqlite3_user_data(sqlite3_context *p){
  assert( p && p->pFunc );