1 /*

     2 ** 2005 May 25

     3 **

     4 ** The author disclaims copyright to this source code.  In place of

     5 ** a legal notice, here is a blessing:

     6 **

     7 **    May you do good and not evil.

     8 **    May you find forgiveness for yourself and forgive others.

     9 **    May you share freely, never taking more than you give.

    10 **

    11 *************************************************************************

    12 ** This file contains the implementation of the sqlite3_prepare()

    13 ** interface, and routines that contribute to loading the database schema

    14 ** from disk.

    15 **

    16 ** $Id: prepare.c,v 1.97 2008/09/08 09:06:19 danielk1977 Exp $

    17 */

    18 #include "sqliteInt.h"

    19 #include <ctype.h>

    20 

    21 /*

    22 ** Fill the InitData structure with an error message that indicates

    23 ** that the database is corrupt.

    24 */

    25 static void corruptSchema(

    26   InitData *pData,     /* Initialization context */

    27   const char *zObj,    /* Object being parsed at the point of error */

    28   const char *zExtra   /* Error information */

    29 ){

    30   sqlite3 *db = pData->db;

    31   if( !db->mallocFailed && (db->flags & SQLITE_RecoveryMode)==0 ){

    32     if( zObj==0 ) zObj = "?";

    33     sqlite3SetString(pData->pzErrMsg, pData->db,

    34        "malformed database schema (%s)", zObj);

    35     if( zExtra && zExtra[0] ){

    36       *pData->pzErrMsg = sqlite3MAppendf(pData->db, *pData->pzErrMsg, "%s - %s",

    37                                   *pData->pzErrMsg, zExtra);

    38     }

    39   }

    40   pData->rc = SQLITE_CORRUPT;

    41 }

    42 

    43 /*

    44 ** This is the callback routine for the code that initializes the

    45 ** database.  See sqlite3Init() below for additional information.

    46 ** This routine is also called from the OP_ParseSchema opcode of the VDBE.

    47 **

    48 ** Each callback contains the following information:

    49 **

    50 **     argv[0] = name of thing being created

    51 **     argv[1] = root page number for table or index. 0 for trigger or view.

    52 **     argv[2] = SQL text for the CREATE statement.

    53 **

    54 */

    55 int sqlite3InitCallback(void *pInit, int argc, char **argv, char **azColName){

    56   InitData *pData = (InitData*)pInit;

    57   sqlite3 *db = pData->db;

    58   int iDb = pData->iDb;

    59 

    60   assert( sqlite3_mutex_held(db->mutex) );

    61   DbClearProperty(db, iDb, DB_Empty);

    62   if( db->mallocFailed ){

    63     corruptSchema(pData, argv[0], 0);

    64     return SQLITE_NOMEM;

    65   }

    66 

    67   assert( argc==3 );

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

    69   if( argv==0 ) return 0;   /* Might happen if EMPTY_RESULT_CALLBACKS are on */

    70   if( argv[1]==0 ){

    71     corruptSchema(pData, argv[0], 0);

    72   }else if( argv[2] && argv[2][0] ){

    73     /* Call the parser to process a CREATE TABLE, INDEX or VIEW.

    74     ** But because db->init.busy is set to 1, no VDBE code is generated

    75     ** or executed.  All the parser does is build the internal data

    76     ** structures that describe the table, index, or view.

    77     */

    78     char *zErr;

    79     int rc;

    80     u8 lookasideEnabled;

    81     assert( db->init.busy );

    82     db->init.iDb = iDb;

    83     db->init.newTnum = atoi(argv[1]);

    84     lookasideEnabled = db->lookaside.bEnabled;

    85     db->lookaside.bEnabled = 0;

    86     rc = sqlite3_exec(db, argv[2], 0, 0, &zErr);

    87     db->init.iDb = 0;

    88     db->lookaside.bEnabled = lookasideEnabled;

    89     assert( rc!=SQLITE_OK || zErr==0 );

    90     if( SQLITE_OK!=rc ){

    91       pData->rc = rc;

    92       if( rc==SQLITE_NOMEM ){

    93         db->mallocFailed = 1;

    94       }else if( rc!=SQLITE_INTERRUPT ){

    95         corruptSchema(pData, argv[0], zErr);

    96       }

    97       sqlite3DbFree(db, zErr);

    98     }

    99   }else if( argv[0]==0 ){

   100     corruptSchema(pData, 0, 0);

   101   }else{

   102     /* If the SQL column is blank it means this is an index that

   103     ** was created to be the PRIMARY KEY or to fulfill a UNIQUE

   104     ** constraint for a CREATE TABLE.  The index should have already

   105     ** been created when we processed the CREATE TABLE.  All we have

   106     ** to do here is record the root page number for that index.

   107     */

   108     Index *pIndex;

   109     pIndex = sqlite3FindIndex(db, argv[0], db->aDb[iDb].zName);

   110     if( pIndex==0 || pIndex->tnum!=0 ){

   111       /* This can occur if there exists an index on a TEMP table which

   112       ** has the same name as another index on a permanent index.  Since

   113       ** the permanent table is hidden by the TEMP table, we can also

   114       ** safely ignore the index on the permanent table.

   115       */

   116       /* Do Nothing */;

   117     }else{

   118       pIndex->tnum = atoi(argv[1]);

   119     }

   120   }

   121   return 0;

   122 }

   123 

   124 /*

   125 ** Attempt to read the database schema and initialize internal

   126 ** data structures for a single database file.  The index of the

   127 ** database file is given by iDb.  iDb==0 is used for the main

   128 ** database.  iDb==1 should never be used.  iDb>=2 is used for

   129 ** auxiliary databases.  Return one of the SQLITE_ error codes to

   130 ** indicate success or failure.

   131 */

   132 static int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg){

   133   int rc;

   134   BtCursor *curMain;

   135   int size;

   136   Table *pTab;

   137   Db *pDb;

   138   char const *azArg[4];

   139   int meta[10];

   140   InitData initData;

   141   char const *zMasterSchema;

   142   char const *zMasterName = SCHEMA_TABLE(iDb);

   143 

   144   /*

   145   ** The master database table has a structure like this

   146   */

   147   static const char master_schema[] = 

   148      "CREATE TABLE sqlite_master(\n"

   149      "  type text,\n"

   150      "  name text,\n"

   151      "  tbl_name text,\n"

   152      "  rootpage integer,\n"

   153      "  sql text\n"

   154      ")"

   155   ;

   156 #ifndef SQLITE_OMIT_TEMPDB

   157   static const char temp_master_schema[] = 

   158      "CREATE TEMP TABLE sqlite_temp_master(\n"

   159      "  type text,\n"

   160      "  name text,\n"

   161      "  tbl_name text,\n"

   162      "  rootpage integer,\n"

   163      "  sql text\n"

   164      ")"

   165   ;

   166 #else

   167   #define temp_master_schema 0

   168 #endif

   169 

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

   171   assert( db->aDb[iDb].pSchema );

   172   assert( sqlite3_mutex_held(db->mutex) );

   173   assert( iDb==1 || sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) );

   174 

   175   /* zMasterSchema and zInitScript are set to point at the master schema

   176   ** and initialisation script appropriate for the database being

   177   ** initialised. zMasterName is the name of the master table.

   178   */

   179   if( !OMIT_TEMPDB && iDb==1 ){

   180     zMasterSchema = temp_master_schema;

   181   }else{

   182     zMasterSchema = master_schema;

   183   }

   184   zMasterName = SCHEMA_TABLE(iDb);

   185 

   186   /* Construct the schema tables.  */

   187   azArg[0] = zMasterName;

   188   azArg[1] = "1";

   189   azArg[2] = zMasterSchema;

   190   azArg[3] = 0;

   191   initData.db = db;

   192   initData.iDb = iDb;

   193   initData.rc = SQLITE_OK;

   194   initData.pzErrMsg = pzErrMsg;

   195   (void)sqlite3SafetyOff(db);

   196   sqlite3InitCallback(&initData, 3, (char **)azArg, 0);

   197   (void)sqlite3SafetyOn(db);

   198   if( initData.rc ){

   199     rc = initData.rc;

   200     goto error_out;

   201   }

   202   pTab = sqlite3FindTable(db, zMasterName, db->aDb[iDb].zName);

   203   if( pTab ){

   204     pTab->tabFlags |= TF_Readonly;

   205   }

   206 

   207   /* Create a cursor to hold the database open

   208   */

   209   pDb = &db->aDb[iDb];

   210   if( pDb->pBt==0 ){

   211     if( !OMIT_TEMPDB && iDb==1 ){

   212       DbSetProperty(db, 1, DB_SchemaLoaded);

   213     }

   214     return SQLITE_OK;

   215   }

   216   curMain = sqlite3MallocZero(sqlite3BtreeCursorSize());

   217   if( !curMain ){

   218     rc = SQLITE_NOMEM;

   219     goto error_out;

   220   }

   221   sqlite3BtreeEnter(pDb->pBt);

   222   rc = sqlite3BtreeCursor(pDb->pBt, MASTER_ROOT, 0, 0, curMain);

   223   if( rc!=SQLITE_OK && rc!=SQLITE_EMPTY ){

   224     sqlite3SetString(pzErrMsg, db, "%s", sqlite3ErrStr(rc));

   225     goto initone_error_out;

   226   }

   227 

   228   /* Get the database meta information.

   229   **

   230   ** Meta values are as follows:

   231   **    meta[0]   Schema cookie.  Changes with each schema change.

   232   **    meta[1]   File format of schema layer.

   233   **    meta[2]   Size of the page cache.

   234   **    meta[3]   Use freelist if 0.  Autovacuum if greater than zero.

   235   **    meta[4]   Db text encoding. 1:UTF-8 2:UTF-16LE 3:UTF-16BE

   236   **    meta[5]   The user cookie. Used by the application.

   237   **    meta[6]   Incremental-vacuum flag.

   238   **    meta[7]

   239   **    meta[8]

   240   **    meta[9]

   241   **

   242   ** Note: The #defined SQLITE_UTF* symbols in sqliteInt.h correspond to

   243   ** the possible values of meta[4].

   244   */

   245   if( rc==SQLITE_OK ){

   246     int i;

   247     for(i=0; i<sizeof(meta)/sizeof(meta[0]); i++){

   248       rc = sqlite3BtreeGetMeta(pDb->pBt, i+1, (u32 *)&meta[i]);

   249       if( rc ){

   250         sqlite3SetString(pzErrMsg, db, "%s", sqlite3ErrStr(rc));

   251         goto initone_error_out;

   252       }

   253     }

   254   }else{

   255     memset(meta, 0, sizeof(meta));

   256   }

   257   pDb->pSchema->schema_cookie = meta[0];

   258 

   259   /* If opening a non-empty database, check the text encoding. For the

   260   ** main database, set sqlite3.enc to the encoding of the main database.

   261   ** For an attached db, it is an error if the encoding is not the same

   262   ** as sqlite3.enc.

   263   */

   264   if( meta[4] ){  /* text encoding */

   265     if( iDb==0 ){

   266       /* If opening the main database, set ENC(db). */

   267       ENC(db) = (u8)meta[4];

   268       db->pDfltColl = sqlite3FindCollSeq(db, SQLITE_UTF8, "BINARY", 6, 0);

   269     }else{

   270       /* If opening an attached database, the encoding much match ENC(db) */

   271       if( meta[4]!=ENC(db) ){

   272         sqlite3SetString(pzErrMsg, db, "attached databases must use the same"

   273             " text encoding as main database");

   274         rc = SQLITE_ERROR;

   275         goto initone_error_out;

   276       }

   277     }

   278   }else{

   279     DbSetProperty(db, iDb, DB_Empty);

   280   }

   281   pDb->pSchema->enc = ENC(db);

   282 

   283   if( pDb->pSchema->cache_size==0 ){

   284     size = meta[2];

   285     if( size==0 ){ size = SQLITE_DEFAULT_CACHE_SIZE; }

   286     if( size<0 ) size = -size;

   287     pDb->pSchema->cache_size = size;

   288     sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);

   289   }

   290 

   291   /*

   292   ** file_format==1    Version 3.0.0.

   293   ** file_format==2    Version 3.1.3.  // ALTER TABLE ADD COLUMN

   294   ** file_format==3    Version 3.1.4.  // ditto but with non-NULL defaults

   295   ** file_format==4    Version 3.3.0.  // DESC indices.  Boolean constants

   296   */

   297   pDb->pSchema->file_format = meta[1];

   298   if( pDb->pSchema->file_format==0 ){

   299     pDb->pSchema->file_format = 1;

   300   }

   301   if( pDb->pSchema->file_format>SQLITE_MAX_FILE_FORMAT ){

   302     sqlite3SetString(pzErrMsg, db, "unsupported file format");

   303     rc = SQLITE_ERROR;

   304     goto initone_error_out;

   305   }

   306 

   307   /* Ticket #2804:  When we open a database in the newer file format,

   308   ** clear the legacy_file_format pragma flag so that a VACUUM will

   309   ** not downgrade the database and thus invalidate any descending

   310   ** indices that the user might have created.

   311   */

   312   if( iDb==0 && meta[1]>=4 ){

   313     db->flags &= ~SQLITE_LegacyFileFmt;

   314   }

   315 

   316   /* Read the schema information out of the schema tables

   317   */

   318   assert( db->init.busy );

   319   if( rc==SQLITE_EMPTY ){

   320     /* For an empty database, there is nothing to read */

   321     rc = SQLITE_OK;

   322   }else{

   323     char *zSql;

   324     zSql = sqlite3MPrintf(db, 

   325         "SELECT name, rootpage, sql FROM '%q'.%s",

   326         db->aDb[iDb].zName, zMasterName);

   327     (void)sqlite3SafetyOff(db);

   328 #ifndef SQLITE_OMIT_AUTHORIZATION

   329     {

   330       int (*xAuth)(void*,int,const char*,const char*,const char*,const char*);

   331       xAuth = db->xAuth;

   332       db->xAuth = 0;

   333 #endif

   334       rc = sqlite3_exec(db, zSql, sqlite3InitCallback, &initData, 0);

   335 #ifndef SQLITE_OMIT_AUTHORIZATION

   336       db->xAuth = xAuth;

   337     }

   338 #endif

   339     if( rc==SQLITE_OK ) rc = initData.rc;

   340     (void)sqlite3SafetyOn(db);

   341     sqlite3DbFree(db, zSql);

   342 #ifndef SQLITE_OMIT_ANALYZE

   343     if( rc==SQLITE_OK ){

   344       sqlite3AnalysisLoad(db, iDb);

   345     }

   346 #endif

   347   }

   348   if( db->mallocFailed ){

   349     rc = SQLITE_NOMEM;

   350     sqlite3ResetInternalSchema(db, 0);

   351   }

   352   if( rc==SQLITE_OK || (db->flags&SQLITE_RecoveryMode)){

   353     /* Black magic: If the SQLITE_RecoveryMode flag is set, then consider

   354     ** the schema loaded, even if errors occured. In this situation the 

   355     ** current sqlite3_prepare() operation will fail, but the following one

   356     ** will attempt to compile the supplied statement against whatever subset

   357     ** of the schema was loaded before the error occured. The primary

   358     ** purpose of this is to allow access to the sqlite_master table

   359     ** even when its contents have been corrupted.

   360     */

   361     DbSetProperty(db, iDb, DB_SchemaLoaded);

   362     rc = SQLITE_OK;

   363   }

   364 

   365   /* Jump here for an error that occurs after successfully allocating

   366   ** curMain and calling sqlite3BtreeEnter(). For an error that occurs

   367   ** before that point, jump to error_out.

   368   */

   369 initone_error_out:

   370   sqlite3BtreeCloseCursor(curMain);

   371   sqlite3_free(curMain);

   372   sqlite3BtreeLeave(pDb->pBt);

   373 

   374 error_out:

   375   if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){

   376     db->mallocFailed = 1;

   377   }

   378   return rc;

   379 }

   380 

   381 /*

   382 ** Initialize all database files - the main database file, the file

   383 ** used to store temporary tables, and any additional database files

   384 ** created using ATTACH statements.  Return a success code.  If an

   385 ** error occurs, write an error message into *pzErrMsg.

   386 **

   387 ** After a database is initialized, the DB_SchemaLoaded bit is set

   388 ** bit is set in the flags field of the Db structure. If the database

   389 ** file was of zero-length, then the DB_Empty flag is also set.

   390 */

   391 int sqlite3Init(sqlite3 *db, char **pzErrMsg){

   392   int i, rc;

   393   int commit_internal = !(db->flags&SQLITE_InternChanges);

   394   

   395   assert( sqlite3_mutex_held(db->mutex) );

   396   if( db->init.busy ) return SQLITE_OK;

   397   rc = SQLITE_OK;

   398   db->init.busy = 1;

   399   for(i=0; rc==SQLITE_OK && i<db->nDb; i++){

   400     if( DbHasProperty(db, i, DB_SchemaLoaded) || i==1 ) continue;

   401     rc = sqlite3InitOne(db, i, pzErrMsg);

   402     if( rc ){

   403       sqlite3ResetInternalSchema(db, i);

   404     }

   405   }

   406 

   407   /* Once all the other databases have been initialised, load the schema

   408   ** for the TEMP database. This is loaded last, as the TEMP database

   409   ** schema may contain references to objects in other databases.

   410   */

   411 #ifndef SQLITE_OMIT_TEMPDB

   412   if( rc==SQLITE_OK && db->nDb>1 && !DbHasProperty(db, 1, DB_SchemaLoaded) ){

   413     rc = sqlite3InitOne(db, 1, pzErrMsg);

   414     if( rc ){

   415       sqlite3ResetInternalSchema(db, 1);

   416     }

   417   }

   418 #endif

   419 

   420   db->init.busy = 0;

   421   if( rc==SQLITE_OK && commit_internal ){

   422     sqlite3CommitInternalChanges(db);

   423   }

   424 

   425   return rc; 

   426 }

   427 

   428 /*

   429 ** This routine is a no-op if the database schema is already initialised.

   430 ** Otherwise, the schema is loaded. An error code is returned.

   431 */

   432 int sqlite3ReadSchema(Parse *pParse){

   433   int rc = SQLITE_OK;

   434   sqlite3 *db = pParse->db;

   435   assert( sqlite3_mutex_held(db->mutex) );

   436   if( !db->init.busy ){

   437     rc = sqlite3Init(db, &pParse->zErrMsg);

   438   }

   439   if( rc!=SQLITE_OK ){

   440     pParse->rc = rc;

   441     pParse->nErr++;

   442   }

   443   return rc;

   444 }

   445 

   446 

   447 /*

   448 ** Check schema cookies in all databases.  If any cookie is out

   449 ** of date, return 0.  If all schema cookies are current, return 1.

   450 */

   451 static int schemaIsValid(sqlite3 *db){

   452   int iDb;

   453   int rc;

   454   BtCursor *curTemp;

   455   int cookie;

   456   int allOk = 1;

   457 

   458   curTemp = (BtCursor *)sqlite3Malloc(sqlite3BtreeCursorSize());

   459   if( curTemp ){

   460     assert( sqlite3_mutex_held(db->mutex) );

   461     for(iDb=0; allOk && iDb<db->nDb; iDb++){

   462       Btree *pBt;

   463       pBt = db->aDb[iDb].pBt;

   464       if( pBt==0 ) continue;

   465       memset(curTemp, 0, sqlite3BtreeCursorSize());

   466       rc = sqlite3BtreeCursor(pBt, MASTER_ROOT, 0, 0, curTemp);

   467       if( rc==SQLITE_OK ){

   468         rc = sqlite3BtreeGetMeta(pBt, 1, (u32 *)&cookie);

   469         if( rc==SQLITE_OK && cookie!=db->aDb[iDb].pSchema->schema_cookie ){

   470           allOk = 0;

   471         }

   472         sqlite3BtreeCloseCursor(curTemp);

   473       }

   474       if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){

   475         db->mallocFailed = 1;

   476       }

   477     }

   478     sqlite3_free(curTemp);

   479   }else{

   480     allOk = 0;

   481     db->mallocFailed = 1;

   482   }

   483 

   484   return allOk;

   485 }

   486 

   487 /*

   488 ** Convert a schema pointer into the iDb index that indicates

   489 ** which database file in db->aDb[] the schema refers to.

   490 **

   491 ** If the same database is attached more than once, the first

   492 ** attached database is returned.

   493 */

   494 int sqlite3SchemaToIndex(sqlite3 *db, Schema *pSchema){

   495   int i = -1000000;

   496 

   497   /* If pSchema is NULL, then return -1000000. This happens when code in 

   498   ** expr.c is trying to resolve a reference to a transient table (i.e. one

   499   ** created by a sub-select). In this case the return value of this 

   500   ** function should never be used.

   501   **

   502   ** We return -1000000 instead of the more usual -1 simply because using

   503   ** -1000000 as incorrectly using -1000000 index into db->aDb[] is much 

   504   ** more likely to cause a segfault than -1 (of course there are assert()

   505   ** statements too, but it never hurts to play the odds).

   506   */

   507   assert( sqlite3_mutex_held(db->mutex) );

   508   if( pSchema ){

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

   510       if( db->aDb[i].pSchema==pSchema ){

   511         break;

   512       }

   513     }

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

   515   }

   516   return i;

   517 }

   518 

   519 /*

   520 ** Compile the UTF-8 encoded SQL statement zSql into a statement handle.

   521 */

   522 static int sqlite3Prepare(

   523   sqlite3 *db,              /* Database handle. */

   524   const char *zSql,         /* UTF-8 encoded SQL statement. */

   525   int nBytes,               /* Length of zSql in bytes. */

   526   int saveSqlFlag,          /* True to copy SQL text into the sqlite3_stmt */

   527   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */

   528   const char **pzTail       /* OUT: End of parsed string */

   529 ){

   530   Parse sParse;

   531   char *zErrMsg = 0;

   532   int rc = SQLITE_OK;

   533   int i;

   534 

   535   assert( ppStmt );

   536   *ppStmt = 0;

   537   if( sqlite3SafetyOn(db) ){

   538     return SQLITE_MISUSE;

   539   }

   540   assert( !db->mallocFailed );

   541   assert( sqlite3_mutex_held(db->mutex) );

   542 

   543   /* If any attached database schemas are locked, do not proceed with

   544   ** compilation. Instead return SQLITE_LOCKED immediately.

   545   */

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

   547     Btree *pBt = db->aDb[i].pBt;

   548     if( pBt ){

   549       int rc;

   550       rc = sqlite3BtreeSchemaLocked(pBt);

   551       if( rc ){

   552         const char *zDb = db->aDb[i].zName;

   553         sqlite3Error(db, SQLITE_LOCKED, "database schema is locked: %s", zDb);

   554         (void)sqlite3SafetyOff(db);

   555         return sqlite3ApiExit(db, SQLITE_LOCKED);

   556       }

   557     }

   558   }

   559   

   560   memset(&sParse, 0, sizeof(sParse));

   561   sParse.db = db;

   562   if( nBytes>=0 && (nBytes==0 || zSql[nBytes-1]!=0) ){

   563     char *zSqlCopy;

   564     int mxLen = db->aLimit[SQLITE_LIMIT_SQL_LENGTH];

   565     if( nBytes>mxLen ){

   566       sqlite3Error(db, SQLITE_TOOBIG, "statement too long");

   567       (void)sqlite3SafetyOff(db);

   568       return sqlite3ApiExit(db, SQLITE_TOOBIG);

   569     }

   570     zSqlCopy = sqlite3DbStrNDup(db, zSql, nBytes);

   571     if( zSqlCopy ){

   572       sqlite3RunParser(&sParse, zSqlCopy, &zErrMsg);

   573       sqlite3DbFree(db, zSqlCopy);

   574       sParse.zTail = &zSql[sParse.zTail-zSqlCopy];

   575     }else{

   576       sParse.zTail = &zSql[nBytes];

   577     }

   578   }else{

   579     sqlite3RunParser(&sParse, zSql, &zErrMsg);

   580   }

   581 

   582   if( db->mallocFailed ){

   583     sParse.rc = SQLITE_NOMEM;

   584   }

   585   if( sParse.rc==SQLITE_DONE ) sParse.rc = SQLITE_OK;

   586   if( sParse.checkSchema && !schemaIsValid(db) ){

   587     sParse.rc = SQLITE_SCHEMA;

   588   }

   589   if( sParse.rc==SQLITE_SCHEMA ){

   590     sqlite3ResetInternalSchema(db, 0);

   591   }

   592   if( db->mallocFailed ){

   593     sParse.rc = SQLITE_NOMEM;

   594   }

   595   if( pzTail ){

   596     *pzTail = sParse.zTail;

   597   }

   598   rc = sParse.rc;

   599 

   600 #ifndef SQLITE_OMIT_EXPLAIN

   601   if( rc==SQLITE_OK && sParse.pVdbe && sParse.explain ){

   602     if( sParse.explain==2 ){

   603       sqlite3VdbeSetNumCols(sParse.pVdbe, 3);

   604       sqlite3VdbeSetColName(sParse.pVdbe, 0, COLNAME_NAME, "order", P4_STATIC);

   605       sqlite3VdbeSetColName(sParse.pVdbe, 1, COLNAME_NAME, "from", P4_STATIC);

   606       sqlite3VdbeSetColName(sParse.pVdbe, 2, COLNAME_NAME, "detail", P4_STATIC);

   607     }else{

   608       sqlite3VdbeSetNumCols(sParse.pVdbe, 8);

   609       sqlite3VdbeSetColName(sParse.pVdbe, 0, COLNAME_NAME, "addr", P4_STATIC);

   610       sqlite3VdbeSetColName(sParse.pVdbe, 1, COLNAME_NAME, "opcode", P4_STATIC);

   611       sqlite3VdbeSetColName(sParse.pVdbe, 2, COLNAME_NAME, "p1", P4_STATIC);

   612       sqlite3VdbeSetColName(sParse.pVdbe, 3, COLNAME_NAME, "p2", P4_STATIC);

   613       sqlite3VdbeSetColName(sParse.pVdbe, 4, COLNAME_NAME, "p3", P4_STATIC);

   614       sqlite3VdbeSetColName(sParse.pVdbe, 5, COLNAME_NAME, "p4", P4_STATIC);

   615       sqlite3VdbeSetColName(sParse.pVdbe, 6, COLNAME_NAME, "p5", P4_STATIC);

   616       sqlite3VdbeSetColName(sParse.pVdbe, 7, COLNAME_NAME, "comment",P4_STATIC);

   617     }

   618   }

   619 #endif

   620 

   621   if( sqlite3SafetyOff(db) ){

   622     rc = SQLITE_MISUSE;

   623   }

   624 

   625   if( saveSqlFlag ){

   626     sqlite3VdbeSetSql(sParse.pVdbe, zSql, sParse.zTail - zSql);

   627   }

   628   if( rc!=SQLITE_OK || db->mallocFailed ){

   629     sqlite3_finalize((sqlite3_stmt*)sParse.pVdbe);

   630     assert(!(*ppStmt));

   631   }else{

   632     *ppStmt = (sqlite3_stmt*)sParse.pVdbe;

   633   }

   634 

   635   if( zErrMsg ){

   636     sqlite3Error(db, rc, "%s", zErrMsg);

   637     sqlite3DbFree(db, zErrMsg);

   638   }else{

   639     sqlite3Error(db, rc, 0);

   640   }

   641 

   642   rc = sqlite3ApiExit(db, rc);

   643   assert( (rc&db->errMask)==rc );

   644   return rc;

   645 }

   646 static int sqlite3LockAndPrepare(

   647   sqlite3 *db,              /* Database handle. */

   648   const char *zSql,         /* UTF-8 encoded SQL statement. */

   649   int nBytes,               /* Length of zSql in bytes. */

   650   int saveSqlFlag,          /* True to copy SQL text into the sqlite3_stmt */

   651   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */

   652   const char **pzTail       /* OUT: End of parsed string */

   653 ){

   654   int rc;

   655   if( !sqlite3SafetyCheckOk(db) ){

   656     return SQLITE_MISUSE;

   657   }

   658   sqlite3_mutex_enter(db->mutex);

   659   sqlite3BtreeEnterAll(db);

   660   rc = sqlite3Prepare(db, zSql, nBytes, saveSqlFlag, ppStmt, pzTail);

   661   sqlite3BtreeLeaveAll(db);

   662   sqlite3_mutex_leave(db->mutex);

   663   return rc;

   664 }

   665 

   666 /*

   667 ** Rerun the compilation of a statement after a schema change.

   668 ** Return true if the statement was recompiled successfully.

   669 ** Return false if there is an error of some kind.

   670 */

   671 int sqlite3Reprepare(Vdbe *p){

   672   int rc;

   673   sqlite3_stmt *pNew;

   674   const char *zSql;

   675   sqlite3 *db;

   676 

   677   assert( sqlite3_mutex_held(sqlite3VdbeDb(p)->mutex) );

   678   zSql = sqlite3_sql((sqlite3_stmt *)p);

   679   assert( zSql!=0 );  /* Reprepare only called for prepare_v2() statements */

   680   db = sqlite3VdbeDb(p);

   681   assert( sqlite3_mutex_held(db->mutex) );

   682   rc = sqlite3LockAndPrepare(db, zSql, -1, 0, &pNew, 0);

   683   if( rc ){

   684     if( rc==SQLITE_NOMEM ){

   685       db->mallocFailed = 1;

   686     }

   687     assert( pNew==0 );

   688     return 0;

   689   }else{

   690     assert( pNew!=0 );

   691   }

   692   sqlite3VdbeSwap((Vdbe*)pNew, p);

   693   sqlite3TransferBindings(pNew, (sqlite3_stmt*)p);

   694   sqlite3VdbeResetStepResult((Vdbe*)pNew);

   695   sqlite3VdbeFinalize((Vdbe*)pNew);

   696   return 1;

   697 }

   698 

   699 

   700 /*

   701 ** Two versions of the official API.  Legacy and new use.  In the legacy

   702 ** version, the original SQL text is not saved in the prepared statement

   703 ** and so if a schema change occurs, SQLITE_SCHEMA is returned by

   704 ** sqlite3_step().  In the new version, the original SQL text is retained

   705 ** and the statement is automatically recompiled if an schema change

   706 ** occurs.

   707 */

   708 int sqlite3_prepare(

   709   sqlite3 *db,              /* Database handle. */

   710   const char *zSql,         /* UTF-8 encoded SQL statement. */

   711   int nBytes,               /* Length of zSql in bytes. */

   712   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */

   713   const char **pzTail       /* OUT: End of parsed string */

   714 ){

   715   int rc;

   716   rc = sqlite3LockAndPrepare(db,zSql,nBytes,0,ppStmt,pzTail);

   717   assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );  /* VERIFY: F13021 */

   718   return rc;

   719 }

   720 int sqlite3_prepare_v2(

   721   sqlite3 *db,              /* Database handle. */

   722   const char *zSql,         /* UTF-8 encoded SQL statement. */

   723   int nBytes,               /* Length of zSql in bytes. */

   724   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */

   725   const char **pzTail       /* OUT: End of parsed string */

   726 ){

   727   int rc;

   728   rc = sqlite3LockAndPrepare(db,zSql,nBytes,1,ppStmt,pzTail);

   729   assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );  /* VERIFY: F13021 */

   730   return rc;

   731 }

   732 

   733 

   734 #ifndef SQLITE_OMIT_UTF16

   735 /*

   736 ** Compile the UTF-16 encoded SQL statement zSql into a statement handle.

   737 */

   738 static int sqlite3Prepare16(

   739   sqlite3 *db,              /* Database handle. */ 

   740   const void *zSql,         /* UTF-8 encoded SQL statement. */

   741   int nBytes,               /* Length of zSql in bytes. */

   742   int saveSqlFlag,          /* True to save SQL text into the sqlite3_stmt */

   743   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */

   744   const void **pzTail       /* OUT: End of parsed string */

   745 ){

   746   /* This function currently works by first transforming the UTF-16

   747   ** encoded string to UTF-8, then invoking sqlite3_prepare(). The

   748   ** tricky bit is figuring out the pointer to return in *pzTail.

   749   */

   750   char *zSql8;

   751   const char *zTail8 = 0;

   752   int rc = SQLITE_OK;

   753 

   754   if( !sqlite3SafetyCheckOk(db) ){

   755     return SQLITE_MISUSE;

   756   }

   757   sqlite3_mutex_enter(db->mutex);

   758   zSql8 = sqlite3Utf16to8(db, zSql, nBytes);

   759   if( zSql8 ){

   760     rc = sqlite3LockAndPrepare(db, zSql8, -1, saveSqlFlag, ppStmt, &zTail8);

   761   }

   762 

   763   if( zTail8 && pzTail ){

   764     /* If sqlite3_prepare returns a tail pointer, we calculate the

   765     ** equivalent pointer into the UTF-16 string by counting the unicode

   766     ** characters between zSql8 and zTail8, and then returning a pointer

   767     ** the same number of characters into the UTF-16 string.

   768     */

   769     int chars_parsed = sqlite3Utf8CharLen(zSql8, zTail8-zSql8);

   770     *pzTail = (u8 *)zSql + sqlite3Utf16ByteLen(zSql, chars_parsed);

   771   }

   772   sqlite3DbFree(db, zSql8); 

   773   rc = sqlite3ApiExit(db, rc);

   774   sqlite3_mutex_leave(db->mutex);

   775   return rc;

   776 }

   777 

   778 /*

   779 ** Two versions of the official API.  Legacy and new use.  In the legacy

   780 ** version, the original SQL text is not saved in the prepared statement

   781 ** and so if a schema change occurs, SQLITE_SCHEMA is returned by

   782 ** sqlite3_step().  In the new version, the original SQL text is retained

   783 ** and the statement is automatically recompiled if an schema change

   784 ** occurs.

   785 */

   786 int sqlite3_prepare16(

   787   sqlite3 *db,              /* Database handle. */ 

   788   const void *zSql,         /* UTF-8 encoded SQL statement. */

   789   int nBytes,               /* Length of zSql in bytes. */

   790   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */

   791   const void **pzTail       /* OUT: End of parsed string */

   792 ){

   793   int rc;

   794   rc = sqlite3Prepare16(db,zSql,nBytes,0,ppStmt,pzTail);

   795   assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );  /* VERIFY: F13021 */

   796   return rc;

   797 }

   798 int sqlite3_prepare16_v2(

   799   sqlite3 *db,              /* Database handle. */ 

   800   const void *zSql,         /* UTF-8 encoded SQL statement. */

   801   int nBytes,               /* Length of zSql in bytes. */

   802   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */

   803   const void **pzTail       /* OUT: End of parsed string */

   804 ){

   805   int rc;

   806   rc = sqlite3Prepare16(db,zSql,nBytes,1,ppStmt,pzTail);

   807   assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );  /* VERIFY: F13021 */

   808   return rc;

   809 }

   810 

   811 #endif /* SQLITE_OMIT_UTF16 */