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.cpp 1282 2008-11-13 09:31:33Z LarsPson $

    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(InitData *pData, const char *zExtra){

    26   if( !pData->db->mallocFailed ){

    27     sqlite3SetString(pData->pzErrMsg, "malformed database schema",

    28        zExtra!=0 && zExtra[0]!=0 ? " - " : (char*)0, zExtra, (char*)0);

    29   }

    30   pData->rc = SQLITE_CORRUPT;

    31 }

    32 

    33 /*

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

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

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

    37 **

    38 ** Each callback contains the following information:

    39 **

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

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

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

    43 **

    44 */

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

    46   InitData *pData = (InitData*)pInit;

    47   sqlite3 *db = pData->db;

    48   int iDb = pData->iDb;

    49 

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

    51   pData->rc = SQLITE_OK;

    52   DbClearProperty(db, iDb, DB_Empty);

    53   if( db->mallocFailed ){

    54     corruptSchema(pData, 0);

    55     return SQLITE_NOMEM;

    56   }

    57 

    58   assert( argc==3 );

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

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

    61     corruptSchema(pData, 0);

    62     return 1;

    63   }

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

    65   if( argv[2] && argv[2][0] ){

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

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

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

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

    70     */

    71     char *zErr;

    72     int rc;

    73     assert( db->init.busy );

    74     db->init.iDb = iDb;

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

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

    77     db->init.iDb = 0;

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

    79     if( SQLITE_OK!=rc ){

    80       pData->rc = rc;

    81       if( rc==SQLITE_NOMEM ){

    82         db->mallocFailed = 1;

    83       }else if( rc!=SQLITE_INTERRUPT ){

    84         corruptSchema(pData, zErr);

    85       }

    86       sqlite3_free(zErr);

    87       return 1;

    88     }

    89   }else{

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

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

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

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

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

    95     */

    96     Index *pIndex;

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

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

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

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

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

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

   103       */

   104       /* Do Nothing */;

   105     }else{

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

   107     }

   108   }

   109   return 0;

   110 }

   111 

   112 /*

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

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

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

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

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

   118 ** indicate success or failure.

   119 */

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

   121   int rc;

   122   BtCursor *curMain;

   123   int size;

   124   Table *pTab;

   125   Db *pDb;

   126   char const *azArg[4];

   127   int meta[10];

   128   InitData initData;

   129   char const *zMasterSchema;

   130   char const *zMasterName = SCHEMA_TABLE(iDb);

   131 

   132   /*

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

   134   */

   135   static const char master_schema[] = 

   136      "CREATE TABLE sqlite_master(\n"

   137      "  type text,\n"

   138      "  name text,\n"

   139      "  tbl_name text,\n"

   140      "  rootpage integer,\n"

   141      "  sql text\n"

   142      ")"

   143   ;

   144 #ifndef SQLITE_OMIT_TEMPDB

   145   static const char temp_master_schema[] = 

   146      "CREATE TEMP TABLE sqlite_temp_master(\n"

   147      "  type text,\n"

   148      "  name text,\n"

   149      "  tbl_name text,\n"

   150      "  rootpage integer,\n"

   151      "  sql text\n"

   152      ")"

   153   ;

   154 #else

   155   #define temp_master_schema 0

   156 #endif

   157 

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

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

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

   161 

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

   163   ** and initialisation script appropriate for the database being

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

   165   */

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

   167     zMasterSchema = temp_master_schema;

   168   }else{

   169     zMasterSchema = master_schema;

   170   }

   171   zMasterName = SCHEMA_TABLE(iDb);

   172 

   173   /* Construct the schema tables.  */

   174   sqlite3SafetyOff(db);

   175   azArg[0] = zMasterName;

   176   azArg[1] = "1";

   177   azArg[2] = zMasterSchema;

   178   azArg[3] = 0;

   179   initData.db = db;

   180   initData.iDb = iDb;

   181   initData.pzErrMsg = pzErrMsg;

   182   rc = sqlite3InitCallback(&initData, 3, (char **)azArg, 0);

   183   if( rc ){

   184     sqlite3SafetyOn(db);

   185     rc = initData.rc;

   186     goto error_out;

   187   }

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

   189   if( pTab ){

   190     pTab->readOnly = 1;

   191   }

   192   sqlite3SafetyOn(db);

   193 

   194   /* Create a cursor to hold the database open

   195   */

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

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

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

   199       DbSetProperty(db, 1, DB_SchemaLoaded);

   200     }

   201     return SQLITE_OK;

   202   }

   203   sqlite3BtreeEnter(pDb->pBt);

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

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

   206     sqlite3SetString(pzErrMsg, sqlite3ErrStr(rc), (char*)0);

   207     sqlite3BtreeLeave(pDb->pBt);

   208     goto error_out;

   209   }

   210 

   211   /* Get the database meta information.

   212   **

   213   ** Meta values are as follows:

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

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

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

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

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

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

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

   221   **    meta[7]

   222   **    meta[8]

   223   **    meta[9]

   224   **

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

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

   227   */

   228   if( rc==SQLITE_OK ){

   229     int i;

   230     for(i=0; rc==SQLITE_OK && i<sizeof(meta)/sizeof(meta[0]); i++){

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

   232     }

   233     if( rc ){

   234       sqlite3SetString(pzErrMsg, sqlite3ErrStr(rc), (char*)0);

   235       sqlite3BtreeCloseCursor(curMain);

   236       sqlite3BtreeLeave(pDb->pBt);

   237       goto error_out;

   238     }

   239   }else{

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

   241   }

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

   243 

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

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

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

   247   ** as sqlite3.enc.

   248   */

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

   250     if( iDb==0 ){

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

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

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

   254     }else{

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

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

   257         sqlite3BtreeCloseCursor(curMain);

   258         sqlite3SetString(pzErrMsg, "attached databases must use the same"

   259             " text encoding as main database", (char*)0);

   260         sqlite3BtreeLeave(pDb->pBt);

   261         return SQLITE_ERROR;

   262       }

   263     }

   264   }else{

   265     DbSetProperty(db, iDb, DB_Empty);

   266   }

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

   268 

   269   size = meta[2];

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

   271   pDb->pSchema->cache_size = size;

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

   273 

   274   /*

   275   ** file_format==1    Version 3.0.0.

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

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

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

   279   */

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

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

   282     pDb->pSchema->file_format = 1;

   283   }

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

   285     sqlite3BtreeCloseCursor(curMain);

   286     sqlite3SetString(pzErrMsg, "unsupported file format", (char*)0);

   287     sqlite3BtreeLeave(pDb->pBt);

   288     return SQLITE_ERROR;

   289   }

   290 

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

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

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

   294   ** indices that the user might have created.

   295   */

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

   297     db->flags &= ~SQLITE_LegacyFileFmt;

   298   }

   299 

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

   301   */

   302   assert( db->init.busy );

   303   if( rc==SQLITE_EMPTY ){

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

   305     rc = SQLITE_OK;

   306   }else{

   307     char *zSql;

   308     zSql = sqlite3MPrintf(db, 

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

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

   311     sqlite3SafetyOff(db);

   312 #ifndef SQLITE_OMIT_AUTHORIZATION

   313     {

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

   315       xAuth = db->xAuth;

   316       db->xAuth = 0;

   317 #endif

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

   319 #ifndef SQLITE_OMIT_AUTHORIZATION

   320       db->xAuth = xAuth;

   321     }

   322 #endif

   323     if( rc==SQLITE_ABORT ) rc = initData.rc;

   324     sqlite3SafetyOn(db);

   325     sqlite3_free(zSql);

   326 #ifndef SQLITE_OMIT_ANALYZE

   327     if( rc==SQLITE_OK ){

   328       sqlite3AnalysisLoad(db, iDb);

   329     }

   330 #endif

   331     sqlite3BtreeCloseCursor(curMain);

   332   }

   333   if( db->mallocFailed ){

   334     /* sqlite3SetString(pzErrMsg, "out of memory", (char*)0); */

   335     rc = SQLITE_NOMEM;

   336     sqlite3ResetInternalSchema(db, 0);

   337   }

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

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

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

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

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

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

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

   345     ** even when its contents have been corrupted.

   346     */

   347     DbSetProperty(db, iDb, DB_SchemaLoaded);

   348     rc = SQLITE_OK;

   349   }

   350   sqlite3BtreeLeave(pDb->pBt);

   351 

   352 error_out:

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

   354     db->mallocFailed = 1;

   355   }

   356   return rc;

   357 }

   358 

   359 /*

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

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

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

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

   364 **

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

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

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

   368 */

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

   370   int i, rc;

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

   372   

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

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

   375   rc = SQLITE_OK;

   376   db->init.busy = 1;

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

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

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

   380     if( rc ){

   381       sqlite3ResetInternalSchema(db, i);

   382     }

   383   }

   384 

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

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

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

   388   */

   389 #ifndef SQLITE_OMIT_TEMPDB

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

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

   392     if( rc ){

   393       sqlite3ResetInternalSchema(db, 1);

   394     }

   395   }

   396 #endif

   397 

   398   db->init.busy = 0;

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

   400     sqlite3CommitInternalChanges(db);

   401   }

   402 

   403   return rc; 

   404 }

   405 

   406 /*

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

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

   409 */

   410 int sqlite3ReadSchema(Parse *pParse){

   411   int rc = SQLITE_OK;

   412   sqlite3 *db = pParse->db;

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

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

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

   416   }

   417   if( rc!=SQLITE_OK ){

   418     pParse->rc = rc;

   419     pParse->nErr++;

   420   }

   421   return rc;

   422 }

   423 

   424 

   425 /*

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

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

   428 */

   429 static int schemaIsValid(sqlite3 *db){

   430   int iDb;

   431   int rc;

   432   BtCursor *curTemp;

   433   int cookie;

   434   int allOk = 1;

   435 

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

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

   438     Btree *pBt;

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

   440     if( pBt==0 ) continue;

   441     rc = sqlite3BtreeCursor(pBt, MASTER_ROOT, 0, 0, 0, &curTemp);

   442     if( rc==SQLITE_OK ){

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

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

   445         allOk = 0;

   446       }

   447       sqlite3BtreeCloseCursor(curTemp);

   448     }

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

   450       db->mallocFailed = 1;

   451     }

   452   }

   453   return allOk;

   454 }

   455 

   456 /*

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

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

   459 **

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

   461 ** attached database is returned.

   462 */

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

   464   int i = -1000000;

   465 

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

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

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

   469   ** function should never be used.

   470   **

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

   472   ** -1000000 as incorrectly using -1000000 index into db->aDb[] is much 

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

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

   475   */

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

   477   if( pSchema ){

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

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

   480         break;

   481       }

   482     }

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

   484   }

   485   return i;

   486 }

   487 

   488 /*

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

   490 */

   491 int sqlite3Prepare(

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

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

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

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

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

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

   498 ){

   499   Parse sParse;

   500   char *zErrMsg = 0;

   501   int rc = SQLITE_OK;

   502   int i;

   503 

   504   assert( ppStmt );

   505   *ppStmt = 0;

   506   if( sqlite3SafetyOn(db) ){

   507     return SQLITE_MISUSE;

   508   }

   509   assert( !db->mallocFailed );

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

   511 

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

   513   ** compilation. Instead return SQLITE_LOCKED immediately.

   514   */

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

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

   517     if( pBt ){

   518       int rc;

   519       rc = sqlite3BtreeSchemaLocked(pBt);

   520       if( rc ){

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

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

   523         sqlite3SafetyOff(db);

   524         return SQLITE_LOCKED;

   525       }

   526     }

   527   }

   528   

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

   530   sParse.db = db;

   531   if( nBytes>=0 && zSql[nBytes]!=0 ){

   532     char *zSqlCopy;

   533     if( nBytes>SQLITE_MAX_SQL_LENGTH ){

   534       return SQLITE_TOOBIG;

   535     }

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

   537     if( zSqlCopy ){

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

   539       sqlite3_free(zSqlCopy);

   540     }

   541     sParse.zTail = &zSql[nBytes];

   542   }else{

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

   544   }

   545 

   546   if( db->mallocFailed ){

   547     sParse.rc = SQLITE_NOMEM;

   548   }

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

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

   551     sParse.rc = SQLITE_SCHEMA;

   552   }

   553   if( sParse.rc==SQLITE_SCHEMA ){

   554     sqlite3ResetInternalSchema(db, 0);

   555   }

   556   if( db->mallocFailed ){

   557     sParse.rc = SQLITE_NOMEM;

   558   }

   559   if( pzTail ){

   560     *pzTail = sParse.zTail;

   561   }

   562   rc = sParse.rc;

   563 

   564 #ifndef SQLITE_OMIT_EXPLAIN

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

   566     if( sParse.explain==2 ){

   567       sqlite3VdbeSetNumCols(sParse.pVdbe, 3);

   568       sqlite3VdbeSetColName(sParse.pVdbe, 0, COLNAME_NAME, "order", P3_STATIC);

   569       sqlite3VdbeSetColName(sParse.pVdbe, 1, COLNAME_NAME, "from", P3_STATIC);

   570       sqlite3VdbeSetColName(sParse.pVdbe, 2, COLNAME_NAME, "detail", P3_STATIC);

   571     }else{

   572       sqlite3VdbeSetNumCols(sParse.pVdbe, 5);

   573       sqlite3VdbeSetColName(sParse.pVdbe, 0, COLNAME_NAME, "addr", P3_STATIC);

   574       sqlite3VdbeSetColName(sParse.pVdbe, 1, COLNAME_NAME, "opcode", P3_STATIC);

   575       sqlite3VdbeSetColName(sParse.pVdbe, 2, COLNAME_NAME, "p1", P3_STATIC);

   576       sqlite3VdbeSetColName(sParse.pVdbe, 3, COLNAME_NAME, "p2", P3_STATIC);

   577       sqlite3VdbeSetColName(sParse.pVdbe, 4, COLNAME_NAME, "p3", P3_STATIC);

   578     }

   579   }

   580 #endif

   581 

   582   if( sqlite3SafetyOff(db) ){

   583     rc = SQLITE_MISUSE;

   584   }

   585 

   586   if( saveSqlFlag ){

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

   588   }

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

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

   591     assert(!(*ppStmt));

   592   }else{

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

   594   }

   595 

   596   if( zErrMsg ){

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

   598     sqlite3_free(zErrMsg);

   599   }else{

   600     sqlite3Error(db, rc, 0);

   601   }

   602 

   603   rc = sqlite3ApiExit(db, rc);

   604   /* sqlite3ReleaseThreadData(); */

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

   606   return rc;

   607 }

   608 static int sqlite3LockAndPrepare(

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

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

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

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

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

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

   615 ){

   616   int rc;

   617   if( sqlite3SafetyCheck(db) ){

   618     return SQLITE_MISUSE;

   619   }

   620   sqlite3_mutex_enter(db->mutex);

   621   sqlite3BtreeEnterAll(db);

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

   623   sqlite3BtreeLeaveAll(db);

   624   sqlite3_mutex_leave(db->mutex);

   625   return rc;

   626 }

   627 

   628 /*

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

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

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

   632 */

   633 int sqlite3Reprepare(Vdbe *p){

   634   int rc;

   635   sqlite3_stmt *pNew;

   636   const char *zSql;

   637   sqlite3 *db;

   638 

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

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

   641   if( zSql==0 ){

   642     return 0;

   643   }

   644   db = sqlite3VdbeDb(p);

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

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

   647   if( rc ){

   648     if( rc==SQLITE_NOMEM ){

   649       db->mallocFailed = 1;

   650     }

   651     assert( pNew==0 );

   652     return 0;

   653   }else{

   654     assert( pNew!=0 );

   655   }

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

   657   sqlite3_transfer_bindings(pNew, (sqlite3_stmt*)p);

   658   sqlite3VdbeResetStepResult((Vdbe*)pNew);

   659   sqlite3VdbeFinalize((Vdbe*)pNew);

   660   return 1;

   661 }

   662 

   663 

   664 /*

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

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

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

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

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

   670 ** occurs.

   671 */

   672 EXPORT_C int sqlite3_prepare(

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

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

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

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

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

   678 ){

   679   return sqlite3LockAndPrepare(db,zSql,nBytes,0,ppStmt,pzTail);

   680 }

   681 EXPORT_C int sqlite3_prepare_v2(

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

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

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

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

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

   687 ){

   688   return sqlite3LockAndPrepare(db,zSql,nBytes,1,ppStmt,pzTail);

   689 }

   690 

   691 

   692 #ifndef SQLITE_OMIT_UTF16

   693 /*

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

   695 */

   696 static int sqlite3Prepare16(

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

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

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

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

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

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

   703 ){

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

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

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

   707   */

   708   char *zSql8;

   709   const char *zTail8 = 0;

   710   int rc = SQLITE_OK;

   711 

   712   if( sqlite3SafetyCheck(db) ){

   713     return SQLITE_MISUSE;

   714   }

   715   sqlite3_mutex_enter(db->mutex);

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

   717   if( zSql8 ){

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

   719   }

   720 

   721   if( zTail8 && pzTail ){

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

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

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

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

   726     */

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

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

   729   }

   730   sqlite3_free(zSql8); 

   731   rc = sqlite3ApiExit(db, rc);

   732   sqlite3_mutex_leave(db->mutex);

   733   return rc;

   734 }

   735 

   736 /*

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

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

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

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

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

   742 ** occurs.

   743 */

   744 EXPORT_C int sqlite3_prepare16(

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

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

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

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

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

   750 ){

   751   return sqlite3Prepare16(db,zSql,nBytes,0,ppStmt,pzTail);

   752 }

   753 EXPORT_C int sqlite3_prepare16_v2(

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

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

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

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

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

   759 ){

   760   return sqlite3Prepare16(db,zSql,nBytes,1,ppStmt,pzTail);

   761 }

   762 

   763 #endif /* SQLITE_OMIT_UTF16 */