**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the implementation of the sqlite3_prepare()
** interface, and routines that contribute to loading the database schema
** from disk.
**
** $Id: prepare.c,v 1.118 2009/05/11 20:53:29 drh Exp $
*/
#include "sqliteInt.h"

/*
** Fill the InitData structure with an error message that indicates
** that the database is corrupt.
*/
................................................................................
  sqlite3 *db,              /* Database handle. */
  const char *zSql,         /* UTF-8 encoded SQL statement. */
  int nBytes,               /* Length of zSql in bytes. */
  int saveSqlFlag,          /* True to copy SQL text into the sqlite3_stmt */
  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
  const char **pzTail       /* OUT: End of parsed string */
){
  Parse sParse;
  char *zErrMsg = 0;
  int rc = SQLITE_OK;
  int i;








  if( sqlite3SafetyOn(db) ) return SQLITE_MISUSE;



  assert( ppStmt && *ppStmt==0 );
  assert( !db->mallocFailed );
  assert( sqlite3_mutex_held(db->mutex) );

  /* Check to verify that it is possible to get a read lock on all
  ** database schemas.  The inability to get a read lock indicates that
  ** some other database connection is holding a write-lock, which in
................................................................................
      assert( sqlite3BtreeHoldsMutex(pBt) );
      rc = sqlite3BtreeSchemaLocked(pBt);
      if( rc ){
        const char *zDb = db->aDb[i].zName;
        sqlite3Error(db, rc, "database schema is locked: %s", zDb);
        (void)sqlite3SafetyOff(db);
        testcase( db->flags & SQLITE_ReadUncommitted );
        return sqlite3ApiExit(db, rc);
      }
    }
  }
  
  memset(&sParse, 0, sizeof(sParse));
  sParse.db = db;
  if( nBytes>=0 && (nBytes==0 || zSql[nBytes-1]!=0) ){
    char *zSqlCopy;
    int mxLen = db->aLimit[SQLITE_LIMIT_SQL_LENGTH];
    if( nBytes>mxLen ){
      sqlite3Error(db, SQLITE_TOOBIG, "statement too long");
      (void)sqlite3SafetyOff(db);
      return sqlite3ApiExit(db, SQLITE_TOOBIG);

    }
    zSqlCopy = sqlite3DbStrNDup(db, zSql, nBytes);
    if( zSqlCopy ){
      sqlite3RunParser(&sParse, zSqlCopy, &zErrMsg);
      sqlite3DbFree(db, zSqlCopy);
      sParse.zTail = &zSql[sParse.zTail-zSqlCopy];
    }else{
      sParse.zTail = &zSql[nBytes];
    }
  }else{
    sqlite3RunParser(&sParse, zSql, &zErrMsg);
  }

  if( db->mallocFailed ){
    sParse.rc = SQLITE_NOMEM;
  }
  if( sParse.rc==SQLITE_DONE ) sParse.rc = SQLITE_OK;
  if( sParse.checkSchema && !schemaIsValid(db) ){
    sParse.rc = SQLITE_SCHEMA;
  }
  if( sParse.rc==SQLITE_SCHEMA ){
    sqlite3ResetInternalSchema(db, 0);
  }
  if( db->mallocFailed ){
    sParse.rc = SQLITE_NOMEM;
  }
  if( pzTail ){
    *pzTail = sParse.zTail;
  }
  rc = sParse.rc;

#ifndef SQLITE_OMIT_EXPLAIN
  if( rc==SQLITE_OK && sParse.pVdbe && sParse.explain ){
    if( sParse.explain==2 ){
      sqlite3VdbeSetNumCols(sParse.pVdbe, 3);
      sqlite3VdbeSetColName(sParse.pVdbe, 0, COLNAME_NAME, "order", SQLITE_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 1, COLNAME_NAME, "from", SQLITE_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 2, COLNAME_NAME, "detail", SQLITE_STATIC);
    }else{
      sqlite3VdbeSetNumCols(sParse.pVdbe, 8);
      sqlite3VdbeSetColName(sParse.pVdbe, 0, COLNAME_NAME, "addr", SQLITE_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 1, COLNAME_NAME, "opcode", SQLITE_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 2, COLNAME_NAME, "p1", SQLITE_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 3, COLNAME_NAME, "p2", SQLITE_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 4, COLNAME_NAME, "p3", SQLITE_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 5, COLNAME_NAME, "p4", SQLITE_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 6, COLNAME_NAME, "p5", SQLITE_STATIC);
      sqlite3VdbeSetColName(sParse.pVdbe, 7, COLNAME_NAME, "comment", SQLITE_STATIC);


    }
  }
#endif

  if( sqlite3SafetyOff(db) ){
    rc = SQLITE_MISUSE;
  }

  assert( db->init.busy==0 || saveSqlFlag==0 );
  if( db->init.busy==0 ){
    Vdbe *pVdbe = sParse.pVdbe;
    sqlite3VdbeSetSql(pVdbe, zSql, (int)(sParse.zTail-zSql), saveSqlFlag);
  }
  if( sParse.pVdbe && (rc!=SQLITE_OK || db->mallocFailed) ){
    sqlite3VdbeFinalize(sParse.pVdbe);
    assert(!(*ppStmt));
  }else{
    *ppStmt = (sqlite3_stmt*)sParse.pVdbe;
  }

  if( zErrMsg ){
    sqlite3Error(db, rc, "%s", zErrMsg);
    sqlite3DbFree(db, zErrMsg);
  }else{
    sqlite3Error(db, rc, 0);
  }




  rc = sqlite3ApiExit(db, rc);
  assert( (rc&db->errMask)==rc );
  return rc;
}
static int sqlite3LockAndPrepare(
  sqlite3 *db,              /* Database handle. */
  const char *zSql,         /* UTF-8 encoded SQL statement. */

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This file contains the implementation of the sqlite3_prepare()
** interface, and routines that contribute to loading the database schema
** from disk.
**
** $Id: prepare.c,v 1.119 2009/06/01 18:18:21 drh Exp $
*/
#include "sqliteInt.h"

/*
** Fill the InitData structure with an error message that indicates
** that the database is corrupt.
*/
................................................................................
  sqlite3 *db,              /* Database handle. */
  const char *zSql,         /* UTF-8 encoded SQL statement. */
  int nBytes,               /* Length of zSql in bytes. */
  int saveSqlFlag,          /* True to copy SQL text into the sqlite3_stmt */
  sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
  const char **pzTail       /* OUT: End of parsed string */
){
  Parse *pParse;            /* Parsing context */
  char *zErrMsg = 0;        /* Error message */
  int rc = SQLITE_OK;       /* Result code */
  int i;                    /* Loop counter */

  /* Allocate the parsing context */
  pParse = sqlite3StackAllocZero(db, sizeof(*pParse));
  if( pParse==0 ){
    rc = SQLITE_NOMEM;
    goto end_prepare;
  }

  if( sqlite3SafetyOn(db) ){
    rc = SQLITE_MISUSE;
    goto end_prepare;
  }
  assert( ppStmt && *ppStmt==0 );
  assert( !db->mallocFailed );
  assert( sqlite3_mutex_held(db->mutex) );

  /* Check to verify that it is possible to get a read lock on all
  ** database schemas.  The inability to get a read lock indicates that
  ** some other database connection is holding a write-lock, which in
................................................................................
      assert( sqlite3BtreeHoldsMutex(pBt) );
      rc = sqlite3BtreeSchemaLocked(pBt);
      if( rc ){
        const char *zDb = db->aDb[i].zName;
        sqlite3Error(db, rc, "database schema is locked: %s", zDb);
        (void)sqlite3SafetyOff(db);
        testcase( db->flags & SQLITE_ReadUncommitted );
        goto end_prepare;
      }
    }
  }


  pParse->db = db;
  if( nBytes>=0 && (nBytes==0 || zSql[nBytes-1]!=0) ){
    char *zSqlCopy;
    int mxLen = db->aLimit[SQLITE_LIMIT_SQL_LENGTH];
    if( nBytes>mxLen ){
      sqlite3Error(db, SQLITE_TOOBIG, "statement too long");
      (void)sqlite3SafetyOff(db);
      rc = sqlite3ApiExit(db, SQLITE_TOOBIG);
      goto end_prepare;
    }
    zSqlCopy = sqlite3DbStrNDup(db, zSql, nBytes);
    if( zSqlCopy ){
      sqlite3RunParser(pParse, zSqlCopy, &zErrMsg);
      sqlite3DbFree(db, zSqlCopy);
      pParse->zTail = &zSql[pParse->zTail-zSqlCopy];
    }else{
      pParse->zTail = &zSql[nBytes];
    }
  }else{
    sqlite3RunParser(pParse, zSql, &zErrMsg);
  }

  if( db->mallocFailed ){
    pParse->rc = SQLITE_NOMEM;
  }
  if( pParse->rc==SQLITE_DONE ) pParse->rc = SQLITE_OK;
  if( pParse->checkSchema && !schemaIsValid(db) ){
    pParse->rc = SQLITE_SCHEMA;
  }
  if( pParse->rc==SQLITE_SCHEMA ){
    sqlite3ResetInternalSchema(db, 0);
  }
  if( db->mallocFailed ){
    pParse->rc = SQLITE_NOMEM;
  }
  if( pzTail ){
    *pzTail = pParse->zTail;
  }
  rc = pParse->rc;

#ifndef SQLITE_OMIT_EXPLAIN
  if( rc==SQLITE_OK && pParse->pVdbe && pParse->explain ){
    static const char * const azColName[] = {
       "addr", "opcode", "p1", "p2", "p3", "p4", "p5", "comment",
       "order", "from", "detail"
    };
    int iFirst, mx;
    if( pParse->explain==2 ){
      sqlite3VdbeSetNumCols(pParse->pVdbe, 3);
      iFirst = 8;
      mx = 11;
    }else{
      sqlite3VdbeSetNumCols(pParse->pVdbe, 8);
      iFirst = 0;
      mx = 8;
    }
    for(i=iFirst; i<mx; i++){
      sqlite3VdbeSetColName(pParse->pVdbe, i-iFirst, COLNAME_NAME,
                            azColName[i], SQLITE_STATIC);
    }
  }
#endif

  if( sqlite3SafetyOff(db) ){
    rc = SQLITE_MISUSE;
  }

  assert( db->init.busy==0 || saveSqlFlag==0 );
  if( db->init.busy==0 ){
    Vdbe *pVdbe = pParse->pVdbe;
    sqlite3VdbeSetSql(pVdbe, zSql, (int)(pParse->zTail-zSql), saveSqlFlag);
  }
  if( pParse->pVdbe && (rc!=SQLITE_OK || db->mallocFailed) ){
    sqlite3VdbeFinalize(pParse->pVdbe);
    assert(!(*ppStmt));
  }else{
    *ppStmt = (sqlite3_stmt*)pParse->pVdbe;
  }

  if( zErrMsg ){
    sqlite3Error(db, rc, "%s", zErrMsg);
    sqlite3DbFree(db, zErrMsg);
  }else{
    sqlite3Error(db, rc, 0);
  }

end_prepare:

  sqlite3StackFree(db, pParse);
  rc = sqlite3ApiExit(db, rc);
  assert( (rc&db->errMask)==rc );
  return rc;
}
static int sqlite3LockAndPrepare(
  sqlite3 *db,              /* Database handle. */
  const char *zSql,         /* UTF-8 encoded SQL statement. */

**    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 1.879 2009/05/30 14:16:32 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** Include the configuration header output by 'configure' if we're using the
** autoconf-based build
................................................................................
*/
#define ROUNDDOWN8(x) ((x)&~7)

/*
** Assert that the pointer X is aligned to an 8-byte boundary.
*/
#define EIGHT_BYTE_ALIGNMENT(X)   ((((char*)(X) - (char*)0)&7)==0)


/*
** An instance of the following structure is used to store the busy-handler
** callback for a given sqlite handle. 
**
** The sqlite.busyHandler member of the sqlite struct contains the busy
** callback for the database handle. Each pager opened via the sqlite
................................................................................
void sqlite3ScratchFree(void*);
void *sqlite3PageMalloc(int);
void sqlite3PageFree(void*);
void sqlite3MemSetDefault(void);
void sqlite3BenignMallocHooks(void (*)(void), void (*)(void));
int sqlite3MemoryAlarm(void (*)(void*, sqlite3_int64, int), void*, sqlite3_int64);



















#ifdef SQLITE_ENABLE_MEMSYS3
const sqlite3_mem_methods *sqlite3MemGetMemsys3(void);
#endif
#ifdef SQLITE_ENABLE_MEMSYS5
const sqlite3_mem_methods *sqlite3MemGetMemsys5(void);
#endif

**    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 1.880 2009/06/01 18:18:21 drh Exp $
*/
#ifndef _SQLITEINT_H_
#define _SQLITEINT_H_

/*
** Include the configuration header output by 'configure' if we're using the
** autoconf-based build
................................................................................
*/
#define ROUNDDOWN8(x) ((x)&~7)

/*
** Assert that the pointer X is aligned to an 8-byte boundary.
*/
#define EIGHT_BYTE_ALIGNMENT(X)   ((((char*)(X) - (char*)0)&7)==0)


/*
** An instance of the following structure is used to store the busy-handler
** callback for a given sqlite handle. 
**
** The sqlite.busyHandler member of the sqlite struct contains the busy
** callback for the database handle. Each pager opened via the sqlite
................................................................................
void sqlite3ScratchFree(void*);
void *sqlite3PageMalloc(int);
void sqlite3PageFree(void*);
void sqlite3MemSetDefault(void);
void sqlite3BenignMallocHooks(void (*)(void), void (*)(void));
int sqlite3MemoryAlarm(void (*)(void*, sqlite3_int64, int), void*, sqlite3_int64);

/*
** On systems with ample stack space and that support alloca(), make
** use of alloca() to obtain space for large automatic objects.  By default,
** obtain space from malloc().
**
** The alloca() routine never returns NULL.  This will cause code paths
** that deal with sqlite3StackAlloc() failures to be unreachable.
*/
#ifdef SQLITE_USE_ALLOCA
# define sqlite3StackAllocRaw(D,N)   alloca(N)
# define sqlite3StackAllocZero(D,N)  memset(alloca(N), 0, N)
# define sqlite3StackFree(D,P)       
#else
# define sqlite3StackAllocRaw(D,N)   sqlite3DbMallocRaw(D,N)
# define sqlite3StackAllocZero(D,N)  sqlite3DbMallocZero(D,N)
# define sqlite3StackFree(D,P)       sqlite3DbFree(D,P)
#endif

#ifdef SQLITE_ENABLE_MEMSYS3
const sqlite3_mem_methods *sqlite3MemGetMemsys3(void);
#endif
#ifdef SQLITE_ENABLE_MEMSYS5
const sqlite3_mem_methods *sqlite3MemGetMemsys5(void);
#endif