src/prepare.c

   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 #include "sqliteInt.h"
  17
  18 /*
  19 ** Fill the InitData structure with an error message that indicates
  20 ** that the database is corrupt.
  21 */
  22 static void corruptSchema(
  23   InitData *pData,     /* Initialization context */
  24   char **azObj,        /* Type and name of object being parsed */
  25   const char *zExtra   /* Error information */
  26 ){
  27   sqlite3 *db = pData->db;
  28   if( db->mallocFailed ){
  29     pData->rc = SQLITE_NOMEM_BKPT;
  30   }else if( pData->pzErrMsg[0]!=0 ){
  31     /* A error message has already been generated.  Do not overwrite it */
  32   }else if( pData->mInitFlags & (INITFLAG_AlterMask) ){
  33     static const char *azAlterType[] = {
  34        "rename",
  35        "drop column",
  36        "add column"
  37     };
  38     *pData->pzErrMsg = sqlite3MPrintf(db,
  39         "error in %s %s after %s: %s", azObj[0], azObj[1],
  40         azAlterType[(pData->mInitFlags&INITFLAG_AlterMask)-1],
  41         zExtra
  42     );
  43     pData->rc = SQLITE_ERROR;
  44   }else if( db->flags & SQLITE_WriteSchema ){
  45     pData->rc = SQLITE_CORRUPT_BKPT;
  46   }else{
  47     char *z;
  48     const char *zObj = azObj[1] ? azObj[1] : "?";
  49     z = sqlite3MPrintf(db, "malformed database schema (%s)", zObj);
  50     if( zExtra && zExtra[0] ) z = sqlite3MPrintf(db, "%z - %s", z, zExtra);
  51     *pData->pzErrMsg = z;
  52     pData->rc = SQLITE_CORRUPT_BKPT;
  53   }
  54 }
  55
  56 /*
  57 ** Check to see if any sibling index (another index on the same table)
  58 ** of pIndex has the same root page number, and if it does, return true.
  59 ** This would indicate a corrupt schema.
  60 */
  61 int sqlite3IndexHasDuplicateRootPage(Index *pIndex){
  62   Index *p;
  63   for(p=pIndex->pTable->pIndex; p; p=p->pNext){
  64     if( p->tnum==pIndex->tnum && p!=pIndex ) return 1;
  65   }
  66   return 0;
  67 }
  68
  69 /* forward declaration */
  70 static int sqlite3Prepare(
  71   sqlite3 *db,              /* Database handle. */
  72   const char *zSql,         /* UTF-8 encoded SQL statement. */
  73   int nBytes,               /* Length of zSql in bytes. */
  74   u32 prepFlags,            /* Zero or more SQLITE_PREPARE_* flags */
  75   Vdbe *pReprepare,         /* VM being reprepared */
  76   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
  77   const char **pzTail       /* OUT: End of parsed string */
  78 );
  79
  80
  81 /*
  82 ** This is the callback routine for the code that initializes the
  83 ** database.  See sqlite3Init() below for additional information.
  84 ** This routine is also called from the OP_ParseSchema opcode of the VDBE.
  85 **
  86 ** Each callback contains the following information:
  87 **
  88 **     argv[0] = type of object: "table", "index", "trigger", or "view".
  89 **     argv[1] = name of thing being created
  90 **     argv[2] = associated table if an index or trigger
  91 **     argv[3] = root page number for table or index. 0 for trigger or view.
  92 **     argv[4] = SQL text for the CREATE statement.
  93 **
  94 */
  95 int sqlite3InitCallback(void *pInit, int argc, char **argv, char **NotUsed){
  96   InitData *pData = (InitData*)pInit;
  97   sqlite3 *db = pData->db;
  98   int iDb = pData->iDb;
  99
 100   assert( argc==5 );
 101   UNUSED_PARAMETER2(NotUsed, argc);
 102   assert( sqlite3_mutex_held(db->mutex) );
 103   db->mDbFlags |= DBFLAG_EncodingFixed;
 104   if( argv==0 ) return 0;   /* Might happen if EMPTY_RESULT_CALLBACKS are on */
 105   pData->nInitRow++;
 106   if( db->mallocFailed ){
 107     corruptSchema(pData, argv, 0);
 108     return 1;
 109   }
 110
 111   assert( iDb>=0 && iDb<db->nDb );
 112   if( argv[3]==0 ){
 113     corruptSchema(pData, argv, 0);
 114   }else if( argv[4]
 115          && 'c'==sqlite3UpperToLower[(unsigned char)argv[4][0]]
 116          && 'r'==sqlite3UpperToLower[(unsigned char)argv[4][1]] ){
 117     /* Call the parser to process a CREATE TABLE, INDEX or VIEW.
 118     ** But because db->init.busy is set to 1, no VDBE code is generated
 119     ** or executed.  All the parser does is build the internal data
 120     ** structures that describe the table, index, or view.
 121     **
 122     ** No other valid SQL statement, other than the variable CREATE statements,
 123     ** can begin with the letters "C" and "R".  Thus, it is not possible run
 124     ** any other kind of statement while parsing the schema, even a corrupt
 125     ** schema.
 126     */
 127     int rc;
 128     u8 saved_iDb = db->init.iDb;
 129     sqlite3_stmt *pStmt;
 130     TESTONLY(int rcp);            /* Return code from sqlite3_prepare() */
 131
 132     assert( db->init.busy );
 133     db->init.iDb = iDb;
 134     if( sqlite3GetUInt32(argv[3], &db->init.newTnum)==0
 135      || (db->init.newTnum>pData->mxPage && pData->mxPage>0)
 136     ){
 137       if( sqlite3Config.bExtraSchemaChecks ){
 138         corruptSchema(pData, argv, "invalid rootpage");
 139       }
 140     }
 141     db->init.orphanTrigger = 0;
 142     db->init.azInit = (const char**)argv;
 143     pStmt = 0;
 144     TESTONLY(rcp = ) sqlite3Prepare(db, argv[4], -1, 0, 0, &pStmt, 0);
 145     rc = db->errCode;
 146     assert( (rc&0xFF)==(rcp&0xFF) );
 147     db->init.iDb = saved_iDb;
 148     /* assert( saved_iDb==0 || (db->mDbFlags & DBFLAG_Vacuum)!=0 ); */
 149     if( SQLITE_OK!=rc ){
 150       if( db->init.orphanTrigger ){
 151         assert( iDb==1 );
 152       }else{
 153         if( rc > pData->rc ) pData->rc = rc;
 154         if( rc==SQLITE_NOMEM ){
 155           sqlite3OomFault(db);
 156         }else if( rc!=SQLITE_INTERRUPT && (rc&0xFF)!=SQLITE_LOCKED ){
 157           corruptSchema(pData, argv, sqlite3_errmsg(db));
 158         }
 159       }
 160     }
 161     db->init.azInit = sqlite3StdType; /* Any array of string ptrs will do */
 162     sqlite3_finalize(pStmt);
 163   }else if( argv[1]==0 || (argv[4]!=0 && argv[4][0]!=0) ){
 164     corruptSchema(pData, argv, 0);
 165   }else{
 166     /* If the SQL column is blank it means this is an index that
 167     ** was created to be the PRIMARY KEY or to fulfill a UNIQUE
 168     ** constraint for a CREATE TABLE.  The index should have already
 169     ** been created when we processed the CREATE TABLE.  All we have
 170     ** to do here is record the root page number for that index.
 171     */
 172     Index *pIndex;
 173     pIndex = sqlite3FindIndex(db, argv[1], db->aDb[iDb].zDbSName);
 174     if( pIndex==0 ){
 175       corruptSchema(pData, argv, "orphan index");
 176     }else
 177     if( sqlite3GetUInt32(argv[3],&pIndex->tnum)==0
 178      || pIndex->tnum<2
 179      || pIndex->tnum>pData->mxPage
 180      || sqlite3IndexHasDuplicateRootPage(pIndex)
 181     ){
 182       if( sqlite3Config.bExtraSchemaChecks ){
 183         corruptSchema(pData, argv, "invalid rootpage");
 184       }
 185     }
 186   }
 187   return 0;
 188 }
 189
 190 /*
 191 ** Attempt to read the database schema and initialize internal
 192 ** data structures for a single database file.  The index of the
 193 ** database file is given by iDb.  iDb==0 is used for the main
 194 ** database.  iDb==1 should never be used.  iDb>=2 is used for
 195 ** auxiliary databases.  Return one of the SQLITE_ error codes to
 196 ** indicate success or failure.
 197 */
 198 int sqlite3InitOne(sqlite3 *db, int iDb, char **pzErrMsg, u32 mFlags){
 199   int rc;
 200   int i;
 201 #ifndef SQLITE_OMIT_DEPRECATED
 202   int size;
 203 #endif
 204   Db *pDb;
 205   char const *azArg[6];
 206   int meta[5];
 207   InitData initData;
 208   const char *zSchemaTabName;
 209   int openedTransaction = 0;
 210   int mask = ((db->mDbFlags & DBFLAG_EncodingFixed) | ~DBFLAG_EncodingFixed);
 211
 212   assert( (db->mDbFlags & DBFLAG_SchemaKnownOk)==0 );
 213   assert( iDb>=0 && iDb<db->nDb );
 214   assert( db->aDb[iDb].pSchema );
 215   assert( sqlite3_mutex_held(db->mutex) );
 216   assert( iDb==1 || sqlite3BtreeHoldsMutex(db->aDb[iDb].pBt) );
 217
 218   db->init.busy = 1;
 219
 220   /* Construct the in-memory representation schema tables (sqlite_schema or
 221   ** sqlite_temp_schema) by invoking the parser directly.  The appropriate
 222   ** table name will be inserted automatically by the parser so we can just
 223   ** use the abbreviation "x" here.  The parser will also automatically tag
 224   ** the schema table as read-only. */
 225   azArg[0] = "table";
 226   azArg[1] = zSchemaTabName = SCHEMA_TABLE(iDb);
 227   azArg[2] = azArg[1];
 228   azArg[3] = "1";
 229   azArg[4] = "CREATE TABLE x(type text,name text,tbl_name text,"
 230                             "rootpage int,sql text)";
 231   azArg[5] = 0;
 232   initData.db = db;
 233   initData.iDb = iDb;
 234   initData.rc = SQLITE_OK;
 235   initData.pzErrMsg = pzErrMsg;
 236   initData.mInitFlags = mFlags;
 237   initData.nInitRow = 0;
 238   initData.mxPage = 0;
 239   sqlite3InitCallback(&initData, 5, (char **)azArg, 0);
 240   db->mDbFlags &= mask;
 241   if( initData.rc ){
 242     rc = initData.rc;
 243     goto error_out;
 244   }
 245
 246   /* Create a cursor to hold the database open
 247   */
 248   pDb = &db->aDb[iDb];
 249   if( pDb->pBt==0 ){
 250     assert( iDb==1 );
 251     DbSetProperty(db, 1, DB_SchemaLoaded);
 252     rc = SQLITE_OK;
 253     goto error_out;
 254   }
 255
 256   /* If there is not already a read-only (or read-write) transaction opened
 257   ** on the b-tree database, open one now. If a transaction is opened, it
 258   ** will be closed before this function returns.  */
 259   sqlite3BtreeEnter(pDb->pBt);
 260   if( sqlite3BtreeTxnState(pDb->pBt)==SQLITE_TXN_NONE ){
 261     rc = sqlite3BtreeBeginTrans(pDb->pBt, 0, 0);
 262     if( rc!=SQLITE_OK ){
 263       sqlite3SetString(pzErrMsg, db, sqlite3ErrStr(rc));
 264       goto initone_error_out;
 265     }
 266     openedTransaction = 1;
 267   }
 268
 269   /* Get the database meta information.
 270   **
 271   ** Meta values are as follows:
 272   **    meta[0]   Schema cookie.  Changes with each schema change.
 273   **    meta[1]   File format of schema layer.
 274   **    meta[2]   Size of the page cache.
 275   **    meta[3]   Largest rootpage (auto/incr_vacuum mode)
 276   **    meta[4]   Db text encoding. 1:UTF-8 2:UTF-16LE 3:UTF-16BE
 277   **    meta[5]   User version
 278   **    meta[6]   Incremental vacuum mode
 279   **    meta[7]   unused
 280   **    meta[8]   unused
 281   **    meta[9]   unused
 282   **
 283   ** Note: The #defined SQLITE_UTF* symbols in sqliteInt.h correspond to
 284   ** the possible values of meta[4].
 285   */
 286   for(i=0; i<ArraySize(meta); i++){
 287     sqlite3BtreeGetMeta(pDb->pBt, i+1, (u32 *)&meta[i]);
 288   }
 289   if( (db->flags & SQLITE_ResetDatabase)!=0 ){
 290     memset(meta, 0, sizeof(meta));
 291   }
 292   pDb->pSchema->schema_cookie = meta[BTREE_SCHEMA_VERSION-1];
 293
 294   /* If opening a non-empty database, check the text encoding. For the
 295   ** main database, set sqlite3.enc to the encoding of the main database.
 296   ** For an attached db, it is an error if the encoding is not the same
 297   ** as sqlite3.enc.
 298   */
 299   if( meta[BTREE_TEXT_ENCODING-1] ){  /* text encoding */
 300     if( iDb==0 && (db->mDbFlags & DBFLAG_EncodingFixed)==0 ){
 301       u8 encoding;
 302 #ifndef SQLITE_OMIT_UTF16
 303       /* If opening the main database, set ENC(db). */
 304       encoding = (u8)meta[BTREE_TEXT_ENCODING-1] & 3;
 305       if( encoding==0 ) encoding = SQLITE_UTF8;
 306 #else
 307       encoding = SQLITE_UTF8;
 308 #endif
 309       sqlite3SetTextEncoding(db, encoding);
 310     }else{
 311       /* If opening an attached database, the encoding much match ENC(db) */
 312       if( (meta[BTREE_TEXT_ENCODING-1] & 3)!=ENC(db) ){
 313         sqlite3SetString(pzErrMsg, db, "attached databases must use the same"
 314             " text encoding as main database");
 315         rc = SQLITE_ERROR;
 316         goto initone_error_out;
 317       }
 318     }
 319   }
 320   pDb->pSchema->enc = ENC(db);
 321
 322   if( pDb->pSchema->cache_size==0 ){
 323 #ifndef SQLITE_OMIT_DEPRECATED
 324     size = sqlite3AbsInt32(meta[BTREE_DEFAULT_CACHE_SIZE-1]);
 325     if( size==0 ){ size = SQLITE_DEFAULT_CACHE_SIZE; }
 326     pDb->pSchema->cache_size = size;
 327 #else
 328     pDb->pSchema->cache_size = SQLITE_DEFAULT_CACHE_SIZE;
 329 #endif
 330     sqlite3BtreeSetCacheSize(pDb->pBt, pDb->pSchema->cache_size);
 331   }
 332
 333   /*
 334   ** file_format==1    Version 3.0.0.
 335   ** file_format==2    Version 3.1.3.  // ALTER TABLE ADD COLUMN
 336   ** file_format==3    Version 3.1.4.  // ditto but with non-NULL defaults
 337   ** file_format==4    Version 3.3.0.  // DESC indices.  Boolean constants
 338   */
 339   pDb->pSchema->file_format = (u8)meta[BTREE_FILE_FORMAT-1];
 340   if( pDb->pSchema->file_format==0 ){
 341     pDb->pSchema->file_format = 1;
 342   }
 343   if( pDb->pSchema->file_format>SQLITE_MAX_FILE_FORMAT ){
 344     sqlite3SetString(pzErrMsg, db, "unsupported file format");
 345     rc = SQLITE_ERROR;
 346     goto initone_error_out;
 347   }
 348
 349   /* Ticket #2804:  When we open a database in the newer file format,
 350   ** clear the legacy_file_format pragma flag so that a VACUUM will
 351   ** not downgrade the database and thus invalidate any descending
 352   ** indices that the user might have created.
 353   */
 354   if( iDb==0 && meta[BTREE_FILE_FORMAT-1]>=4 ){
 355     db->flags &= ~(u64)SQLITE_LegacyFileFmt;
 356   }
 357
 358   /* Read the schema information out of the schema tables
 359   */
 360   assert( db->init.busy );
 361   initData.mxPage = sqlite3BtreeLastPage(pDb->pBt);
 362   {
 363     char *zSql;
 364     zSql = sqlite3MPrintf(db,
 365         "SELECT*FROM\"%w\".%s ORDER BY rowid",
 366         db->aDb[iDb].zDbSName, zSchemaTabName);
 367 #ifndef SQLITE_OMIT_AUTHORIZATION
 368     {
 369       sqlite3_xauth xAuth;
 370       xAuth = db->xAuth;
 371       db->xAuth = 0;
 372 #endif
 373       rc = sqlite3_exec(db, zSql, sqlite3InitCallback, &initData, 0);
 374 #ifndef SQLITE_OMIT_AUTHORIZATION
 375       db->xAuth = xAuth;
 376     }
 377 #endif
 378     if( rc==SQLITE_OK ) rc = initData.rc;
 379     sqlite3DbFree(db, zSql);
 380 #ifndef SQLITE_OMIT_ANALYZE
 381     if( rc==SQLITE_OK ){
 382       sqlite3AnalysisLoad(db, iDb);
 383     }
 384 #endif
 385   }
 386   assert( pDb == &(db->aDb[iDb]) );
 387   if( db->mallocFailed ){
 388     rc = SQLITE_NOMEM_BKPT;
 389     sqlite3ResetAllSchemasOfConnection(db);
 390     pDb = &db->aDb[iDb];
 391   }else
 392   if( rc==SQLITE_OK || (db->flags&SQLITE_NoSchemaError)){
 393     /* Hack: If the SQLITE_NoSchemaError flag is set, then consider
 394     ** the schema loaded, even if errors (other than OOM) occurred. In
 395     ** this situation the current sqlite3_prepare() operation will fail,
 396     ** but the following one will attempt to compile the supplied statement
 397     ** against whatever subset of the schema was loaded before the error
 398     ** occurred.
 399     **
 400     ** The primary purpose of this is to allow access to the sqlite_schema
 401     ** table even when its contents have been corrupted.
 402     */
 403     DbSetProperty(db, iDb, DB_SchemaLoaded);
 404     rc = SQLITE_OK;
 405   }
 406
 407   /* Jump here for an error that occurs after successfully allocating
 408   ** curMain and calling sqlite3BtreeEnter(). For an error that occurs
 409   ** before that point, jump to error_out.
 410   */
 411 initone_error_out:
 412   if( openedTransaction ){
 413     sqlite3BtreeCommit(pDb->pBt);
 414   }
 415   sqlite3BtreeLeave(pDb->pBt);
 416
 417 error_out:
 418   if( rc ){
 419     if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
 420       sqlite3OomFault(db);
 421     }
 422     sqlite3ResetOneSchema(db, iDb);
 423   }
 424   db->init.busy = 0;
 425   return rc;
 426 }
 427
 428 /*
 429 ** Initialize all database files - the main database file, the file
 430 ** used to store temporary tables, and any additional database files
 431 ** created using ATTACH statements.  Return a success code.  If an
 432 ** error occurs, write an error message into *pzErrMsg.
 433 **
 434 ** After a database is initialized, the DB_SchemaLoaded bit is set
 435 ** bit is set in the flags field of the Db structure.
 436 */
 437 int sqlite3Init(sqlite3 *db, char **pzErrMsg){
 438   int i, rc;
 439   int commit_internal = !(db->mDbFlags&DBFLAG_SchemaChange);
 440
 441   assert( sqlite3_mutex_held(db->mutex) );
 442   assert( sqlite3BtreeHoldsMutex(db->aDb[0].pBt) );
 443   assert( db->init.busy==0 );
 444   ENC(db) = SCHEMA_ENC(db);
 445   assert( db->nDb>0 );
 446   /* Do the main schema first */
 447   if( !DbHasProperty(db, 0, DB_SchemaLoaded) ){
 448     rc = sqlite3InitOne(db, 0, pzErrMsg, 0);
 449     if( rc ) return rc;
 450   }
 451   /* All other schemas after the main schema. The "temp" schema must be last */
 452   for(i=db->nDb-1; i>0; i--){
 453     assert( i==1 || sqlite3BtreeHoldsMutex(db->aDb[i].pBt) );
 454     if( !DbHasProperty(db, i, DB_SchemaLoaded) ){
 455       rc = sqlite3InitOne(db, i, pzErrMsg, 0);
 456       if( rc ) return rc;
 457     }
 458   }
 459   if( commit_internal ){
 460     sqlite3CommitInternalChanges(db);
 461   }
 462   return SQLITE_OK;
 463 }
 464
 465 /*
 466 ** This routine is a no-op if the database schema is already initialized.
 467 ** Otherwise, the schema is loaded. An error code is returned.
 468 */
 469 int sqlite3ReadSchema(Parse *pParse){
 470   int rc = SQLITE_OK;
 471   sqlite3 *db = pParse->db;
 472   assert( sqlite3_mutex_held(db->mutex) );
 473   if( !db->init.busy ){
 474     rc = sqlite3Init(db, &pParse->zErrMsg);
 475     if( rc!=SQLITE_OK ){
 476       pParse->rc = rc;
 477       pParse->nErr++;
 478     }else if( db->noSharedCache ){
 479       db->mDbFlags |= DBFLAG_SchemaKnownOk;
 480     }
 481   }
 482   return rc;
 483 }
 484
 485
 486 /*
 487 ** Check schema cookies in all databases.  If any cookie is out
 488 ** of date set pParse->rc to SQLITE_SCHEMA.  If all schema cookies
 489 ** make no changes to pParse->rc.
 490 */
 491 static void schemaIsValid(Parse *pParse){
 492   sqlite3 *db = pParse->db;
 493   int iDb;
 494   int rc;
 495   int cookie;
 496
 497   assert( pParse->checkSchema );
 498   assert( sqlite3_mutex_held(db->mutex) );
 499   for(iDb=0; iDb<db->nDb; iDb++){
 500     int openedTransaction = 0;         /* True if a transaction is opened */
 501     Btree *pBt = db->aDb[iDb].pBt;     /* Btree database to read cookie from */
 502     if( pBt==0 ) continue;
 503
 504     /* If there is not already a read-only (or read-write) transaction opened
 505     ** on the b-tree database, open one now. If a transaction is opened, it
 506     ** will be closed immediately after reading the meta-value. */
 507     if( sqlite3BtreeTxnState(pBt)==SQLITE_TXN_NONE ){
 508       rc = sqlite3BtreeBeginTrans(pBt, 0, 0);
 509       if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
 510         sqlite3OomFault(db);
 511         pParse->rc = SQLITE_NOMEM;
 512       }
 513       if( rc!=SQLITE_OK ) return;
 514       openedTransaction = 1;
 515     }
 516
 517     /* Read the schema cookie from the database. If it does not match the
 518     ** value stored as part of the in-memory schema representation,
 519     ** set Parse.rc to SQLITE_SCHEMA. */
 520     sqlite3BtreeGetMeta(pBt, BTREE_SCHEMA_VERSION, (u32 *)&cookie);
 521     assert( sqlite3SchemaMutexHeld(db, iDb, 0) );
 522     if( cookie!=db->aDb[iDb].pSchema->schema_cookie ){
 523       sqlite3ResetOneSchema(db, iDb);
 524       pParse->rc = SQLITE_SCHEMA;
 525     }
 526
 527     /* Close the transaction, if one was opened. */
 528     if( openedTransaction ){
 529       sqlite3BtreeCommit(pBt);
 530     }
 531   }
 532 }
 533
 534 /*
 535 ** Convert a schema pointer into the iDb index that indicates
 536 ** which database file in db->aDb[] the schema refers to.
 537 **
 538 ** If the same database is attached more than once, the first
 539 ** attached database is returned.
 540 */
 541 int sqlite3SchemaToIndex(sqlite3 *db, Schema *pSchema){
 542   int i = -32768;
 543
 544   /* If pSchema is NULL, then return -32768. This happens when code in
 545   ** expr.c is trying to resolve a reference to a transient table (i.e. one
 546   ** created by a sub-select). In this case the return value of this
 547   ** function should never be used.
 548   **
 549   ** We return -32768 instead of the more usual -1 simply because using
 550   ** -32768 as the incorrect index into db->aDb[] is much
 551   ** more likely to cause a segfault than -1 (of course there are assert()
 552   ** statements too, but it never hurts to play the odds) and
 553   ** -32768 will still fit into a 16-bit signed integer.
 554   */
 555   assert( sqlite3_mutex_held(db->mutex) );
 556   if( pSchema ){
 557     for(i=0; 1; i++){
 558       assert( i<db->nDb );
 559       if( db->aDb[i].pSchema==pSchema ){
 560         break;
 561       }
 562     }
 563     assert( i>=0 && i<db->nDb );
 564   }
 565   return i;
 566 }
 567
 568 /*
 569 ** Free all memory allocations in the pParse object
 570 */
 571 void sqlite3ParserReset(Parse *pParse){
 572   sqlite3 *db = pParse->db;
 573   while( pParse->pCleanup ){
 574     ParseCleanup *pCleanup = pParse->pCleanup;
 575     pParse->pCleanup = pCleanup->pNext;
 576     pCleanup->xCleanup(db, pCleanup->pPtr);
 577     sqlite3DbFreeNN(db, pCleanup);
 578   }
 579   sqlite3DbFree(db, pParse->aLabel);
 580   if( pParse->pConstExpr ){
 581     sqlite3ExprListDelete(db, pParse->pConstExpr);
 582   }
 583   if( db ){
 584     assert( db->lookaside.bDisable >= pParse->disableLookaside );
 585     db->lookaside.bDisable -= pParse->disableLookaside;
 586     db->lookaside.sz = db->lookaside.bDisable ? 0 : db->lookaside.szTrue;
 587   }
 588   pParse->disableLookaside = 0;
 589 }
 590
 591 /*
 592 ** Add a new cleanup operation to a Parser.  The cleanup should happen when
 593 ** the parser object is destroyed.  But, beware: the cleanup might happen
 594 ** immediately.
 595 **
 596 ** Use this mechanism for uncommon cleanups.  There is a higher setup
 597 ** cost for this mechansim (an extra malloc), so it should not be used
 598 ** for common cleanups that happen on most calls.  But for less
 599 ** common cleanups, we save a single NULL-pointer comparison in
 600 ** sqlite3ParserReset(), which reduces the total CPU cycle count.
 601 **
 602 ** If a memory allocation error occurs, then the cleanup happens immediately.
 603 ** When either SQLITE_DEBUG or SQLITE_COVERAGE_TEST are defined, the
 604 ** pParse->earlyCleanup flag is set in that case.  Calling code show verify
 605 ** that test cases exist for which this happens, to guard against possible
 606 ** use-after-free errors following an OOM.  The preferred way to do this is
 607 ** to immediately follow the call to this routine with:
 608 **
 609 **       testcase( pParse->earlyCleanup );
 610 **
 611 ** This routine returns a copy of its pPtr input (the third parameter)
 612 ** except if an early cleanup occurs, in which case it returns NULL.  So
 613 ** another way to check for early cleanup is to check the return value.
 614 ** Or, stop using the pPtr parameter with this call and use only its
 615 ** return value thereafter.  Something like this:
 616 **
 617 **       pObj = sqlite3ParserAddCleanup(pParse, destructor, pObj);
 618 */
 619 void *sqlite3ParserAddCleanup(
 620   Parse *pParse,                      /* Destroy when this Parser finishes */
 621   void (*xCleanup)(sqlite3*,void*),   /* The cleanup routine */
 622   void *pPtr                          /* Pointer to object to be cleaned up */
 623 ){
 624   ParseCleanup *pCleanup = sqlite3DbMallocRaw(pParse->db, sizeof(*pCleanup));
 625   if( pCleanup ){
 626     pCleanup->pNext = pParse->pCleanup;
 627     pParse->pCleanup = pCleanup;
 628     pCleanup->pPtr = pPtr;
 629     pCleanup->xCleanup = xCleanup;
 630   }else{
 631     xCleanup(pParse->db, pPtr);
 632     pPtr = 0;
 633 #if defined(SQLITE_DEBUG) || defined(SQLITE_COVERAGE_TEST)
 634     pParse->earlyCleanup = 1;
 635 #endif
 636   }
 637   return pPtr;
 638 }
 639
 640 /*
 641 ** Compile the UTF-8 encoded SQL statement zSql into a statement handle.
 642 */
 643 static int sqlite3Prepare(
 644   sqlite3 *db,              /* Database handle. */
 645   const char *zSql,         /* UTF-8 encoded SQL statement. */
 646   int nBytes,               /* Length of zSql in bytes. */
 647   u32 prepFlags,            /* Zero or more SQLITE_PREPARE_* flags */
 648   Vdbe *pReprepare,         /* VM being reprepared */
 649   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
 650   const char **pzTail       /* OUT: End of parsed string */
 651 ){
 652   char *zErrMsg = 0;        /* Error message */
 653   int rc = SQLITE_OK;       /* Result code */
 654   int i;                    /* Loop counter */
 655   Parse sParse;             /* Parsing context */
 656
 657   memset(&sParse, 0, PARSE_HDR_SZ);
 658   memset(PARSE_TAIL(&sParse), 0, PARSE_TAIL_SZ);
 659   sParse.pReprepare = pReprepare;
 660   assert( ppStmt && *ppStmt==0 );
 661   /* assert( !db->mallocFailed ); // not true with SQLITE_USE_ALLOCA */
 662   assert( sqlite3_mutex_held(db->mutex) );
 663
 664   /* For a long-term use prepared statement avoid the use of
 665   ** lookaside memory.
 666   */
 667   if( prepFlags & SQLITE_PREPARE_PERSISTENT ){
 668     sParse.disableLookaside++;
 669     DisableLookaside;
 670   }
 671   sParse.disableVtab = (prepFlags & SQLITE_PREPARE_NO_VTAB)!=0;
 672
 673   /* Check to verify that it is possible to get a read lock on all
 674   ** database schemas.  The inability to get a read lock indicates that
 675   ** some other database connection is holding a write-lock, which in
 676   ** turn means that the other connection has made uncommitted changes
 677   ** to the schema.
 678   **
 679   ** Were we to proceed and prepare the statement against the uncommitted
 680   ** schema changes and if those schema changes are subsequently rolled
 681   ** back and different changes are made in their place, then when this
 682   ** prepared statement goes to run the schema cookie would fail to detect
 683   ** the schema change.  Disaster would follow.
 684   **
 685   ** This thread is currently holding mutexes on all Btrees (because
 686   ** of the sqlite3BtreeEnterAll() in sqlite3LockAndPrepare()) so it
 687   ** is not possible for another thread to start a new schema change
 688   ** while this routine is running.  Hence, we do not need to hold
 689   ** locks on the schema, we just need to make sure nobody else is
 690   ** holding them.
 691   **
 692   ** Note that setting READ_UNCOMMITTED overrides most lock detection,
 693   ** but it does *not* override schema lock detection, so this all still
 694   ** works even if READ_UNCOMMITTED is set.
 695   */
 696   if( !db->noSharedCache ){
 697     for(i=0; i<db->nDb; i++) {
 698       Btree *pBt = db->aDb[i].pBt;
 699       if( pBt ){
 700         assert( sqlite3BtreeHoldsMutex(pBt) );
 701         rc = sqlite3BtreeSchemaLocked(pBt);
 702         if( rc ){
 703           const char *zDb = db->aDb[i].zDbSName;
 704           sqlite3ErrorWithMsg(db, rc, "database schema is locked: %s", zDb);
 705           testcase( db->flags & SQLITE_ReadUncommit );
 706           goto end_prepare;
 707         }
 708       }
 709     }
 710   }
 711
 712   sqlite3VtabUnlockList(db);
 713
 714   sParse.db = db;
 715   if( nBytes>=0 && (nBytes==0 || zSql[nBytes-1]!=0) ){
 716     char *zSqlCopy;
 717     int mxLen = db->aLimit[SQLITE_LIMIT_SQL_LENGTH];
 718     testcase( nBytes==mxLen );
 719     testcase( nBytes==mxLen+1 );
 720     if( nBytes>mxLen ){
 721       sqlite3ErrorWithMsg(db, SQLITE_TOOBIG, "statement too long");
 722       rc = sqlite3ApiExit(db, SQLITE_TOOBIG);
 723       goto end_prepare;
 724     }
 725     zSqlCopy = sqlite3DbStrNDup(db, zSql, nBytes);
 726     if( zSqlCopy ){
 727       sqlite3RunParser(&sParse, zSqlCopy, &zErrMsg);
 728       sParse.zTail = &zSql[sParse.zTail-zSqlCopy];
 729       sqlite3DbFree(db, zSqlCopy);
 730     }else{
 731       sParse.zTail = &zSql[nBytes];
 732     }
 733   }else{
 734     sqlite3RunParser(&sParse, zSql, &zErrMsg);
 735   }
 736   assert( 0==sParse.nQueryLoop );
 737
 738   if( pzTail ){
 739     *pzTail = sParse.zTail;
 740   }
 741
 742   if( db->init.busy==0 ){
 743     sqlite3VdbeSetSql(sParse.pVdbe, zSql, (int)(sParse.zTail-zSql), prepFlags);
 744   }
 745   if( db->mallocFailed ){
 746     sParse.rc = SQLITE_NOMEM_BKPT;
 747     sParse.checkSchema = 0;
 748   }
 749   if( sParse.rc!=SQLITE_OK && sParse.rc!=SQLITE_DONE ){
 750     if( sParse.checkSchema && db->init.busy==0 ){
 751       schemaIsValid(&sParse);
 752     }
 753     if( sParse.pVdbe ){
 754       sqlite3VdbeFinalize(sParse.pVdbe);
 755     }
 756     assert( 0==(*ppStmt) );
 757     rc = sParse.rc;
 758     if( zErrMsg ){
 759       sqlite3ErrorWithMsg(db, rc, "%s", zErrMsg);
 760       sqlite3DbFree(db, zErrMsg);
 761     }else{
 762       sqlite3Error(db, rc);
 763     }
 764   }else{
 765     assert( zErrMsg==0 );
 766     *ppStmt = (sqlite3_stmt*)sParse.pVdbe;
 767     rc = SQLITE_OK;
 768     sqlite3ErrorClear(db);
 769   }
 770
 771
 772   /* Delete any TriggerPrg structures allocated while parsing this statement. */
 773   while( sParse.pTriggerPrg ){
 774     TriggerPrg *pT = sParse.pTriggerPrg;
 775     sParse.pTriggerPrg = pT->pNext;
 776     sqlite3DbFree(db, pT);
 777   }
 778
 779 end_prepare:
 780
 781   sqlite3ParserReset(&sParse);
 782   return rc;
 783 }
 784 static int sqlite3LockAndPrepare(
 785   sqlite3 *db,              /* Database handle. */
 786   const char *zSql,         /* UTF-8 encoded SQL statement. */
 787   int nBytes,               /* Length of zSql in bytes. */
 788   u32 prepFlags,            /* Zero or more SQLITE_PREPARE_* flags */
 789   Vdbe *pOld,               /* VM being reprepared */
 790   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
 791   const char **pzTail       /* OUT: End of parsed string */
 792 ){
 793   int rc;
 794   int cnt = 0;
 795
 796 #ifdef SQLITE_ENABLE_API_ARMOR
 797   if( ppStmt==0 ) return SQLITE_MISUSE_BKPT;
 798 #endif
 799   *ppStmt = 0;
 800   if( !sqlite3SafetyCheckOk(db)||zSql==0 ){
 801     return SQLITE_MISUSE_BKPT;
 802   }
 803   sqlite3_mutex_enter(db->mutex);
 804   sqlite3BtreeEnterAll(db);
 805   do{
 806     /* Make multiple attempts to compile the SQL, until it either succeeds
 807     ** or encounters a permanent error.  A schema problem after one schema
 808     ** reset is considered a permanent error. */
 809     rc = sqlite3Prepare(db, zSql, nBytes, prepFlags, pOld, ppStmt, pzTail);
 810     assert( rc==SQLITE_OK || *ppStmt==0 );
 811     if( rc==SQLITE_OK || db->mallocFailed ) break;
 812   }while( rc==SQLITE_ERROR_RETRY
 813        || (rc==SQLITE_SCHEMA && (sqlite3ResetOneSchema(db,-1), cnt++)==0) );
 814   sqlite3BtreeLeaveAll(db);
 815   rc = sqlite3ApiExit(db, rc);
 816   assert( (rc&db->errMask)==rc );
 817   db->busyHandler.nBusy = 0;
 818   sqlite3_mutex_leave(db->mutex);
 819   return rc;
 820 }
 821
 822
 823 /*
 824 ** Rerun the compilation of a statement after a schema change.
 825 **
 826 ** If the statement is successfully recompiled, return SQLITE_OK. Otherwise,
 827 ** if the statement cannot be recompiled because another connection has
 828 ** locked the sqlite3_schema table, return SQLITE_LOCKED. If any other error
 829 ** occurs, return SQLITE_SCHEMA.
 830 */
 831 int sqlite3Reprepare(Vdbe *p){
 832   int rc;
 833   sqlite3_stmt *pNew;
 834   const char *zSql;
 835   sqlite3 *db;
 836   u8 prepFlags;
 837
 838   assert( sqlite3_mutex_held(sqlite3VdbeDb(p)->mutex) );
 839   zSql = sqlite3_sql((sqlite3_stmt *)p);
 840   assert( zSql!=0 );  /* Reprepare only called for prepare_v2() statements */
 841   db = sqlite3VdbeDb(p);
 842   assert( sqlite3_mutex_held(db->mutex) );
 843   prepFlags = sqlite3VdbePrepareFlags(p);
 844   rc = sqlite3LockAndPrepare(db, zSql, -1, prepFlags, p, &pNew, 0);
 845   if( rc ){
 846     if( rc==SQLITE_NOMEM ){
 847       sqlite3OomFault(db);
 848     }
 849     assert( pNew==0 );
 850     return rc;
 851   }else{
 852     assert( pNew!=0 );
 853   }
 854   sqlite3VdbeSwap((Vdbe*)pNew, p);
 855   sqlite3TransferBindings(pNew, (sqlite3_stmt*)p);
 856   sqlite3VdbeResetStepResult((Vdbe*)pNew);
 857   sqlite3VdbeFinalize((Vdbe*)pNew);
 858   return SQLITE_OK;
 859 }
 860
 861
 862 /*
 863 ** Two versions of the official API.  Legacy and new use.  In the legacy
 864 ** version, the original SQL text is not saved in the prepared statement
 865 ** and so if a schema change occurs, SQLITE_SCHEMA is returned by
 866 ** sqlite3_step().  In the new version, the original SQL text is retained
 867 ** and the statement is automatically recompiled if an schema change
 868 ** occurs.
 869 */
 870 int sqlite3_prepare(
 871   sqlite3 *db,              /* Database handle. */
 872   const char *zSql,         /* UTF-8 encoded SQL statement. */
 873   int nBytes,               /* Length of zSql in bytes. */
 874   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
 875   const char **pzTail       /* OUT: End of parsed string */
 876 ){
 877   int rc;
 878   rc = sqlite3LockAndPrepare(db,zSql,nBytes,0,0,ppStmt,pzTail);
 879   assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );  /* VERIFY: F13021 */
 880   return rc;
 881 }
 882 int sqlite3_prepare_v2(
 883   sqlite3 *db,              /* Database handle. */
 884   const char *zSql,         /* UTF-8 encoded SQL statement. */
 885   int nBytes,               /* Length of zSql in bytes. */
 886   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
 887   const char **pzTail       /* OUT: End of parsed string */
 888 ){
 889   int rc;
 890   /* EVIDENCE-OF: R-37923-12173 The sqlite3_prepare_v2() interface works
 891   ** exactly the same as sqlite3_prepare_v3() with a zero prepFlags
 892   ** parameter.
 893   **
 894   ** Proof in that the 5th parameter to sqlite3LockAndPrepare is 0 */
 895   rc = sqlite3LockAndPrepare(db,zSql,nBytes,SQLITE_PREPARE_SAVESQL,0,
 896                              ppStmt,pzTail);
 897   assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );
 898   return rc;
 899 }
 900 int sqlite3_prepare_v3(
 901   sqlite3 *db,              /* Database handle. */
 902   const char *zSql,         /* UTF-8 encoded SQL statement. */
 903   int nBytes,               /* Length of zSql in bytes. */
 904   unsigned int prepFlags,   /* Zero or more SQLITE_PREPARE_* flags */
 905   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
 906   const char **pzTail       /* OUT: End of parsed string */
 907 ){
 908   int rc;
 909   /* EVIDENCE-OF: R-56861-42673 sqlite3_prepare_v3() differs from
 910   ** sqlite3_prepare_v2() only in having the extra prepFlags parameter,
 911   ** which is a bit array consisting of zero or more of the
 912   ** SQLITE_PREPARE_* flags.
 913   **
 914   ** Proof by comparison to the implementation of sqlite3_prepare_v2()
 915   ** directly above. */
 916   rc = sqlite3LockAndPrepare(db,zSql,nBytes,
 917                  SQLITE_PREPARE_SAVESQL|(prepFlags&SQLITE_PREPARE_MASK),
 918                  0,ppStmt,pzTail);
 919   assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );
 920   return rc;
 921 }
 922
 923
 924 #ifndef SQLITE_OMIT_UTF16
 925 /*
 926 ** Compile the UTF-16 encoded SQL statement zSql into a statement handle.
 927 */
 928 static int sqlite3Prepare16(
 929   sqlite3 *db,              /* Database handle. */
 930   const void *zSql,         /* UTF-16 encoded SQL statement. */
 931   int nBytes,               /* Length of zSql in bytes. */
 932   u32 prepFlags,            /* Zero or more SQLITE_PREPARE_* flags */
 933   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
 934   const void **pzTail       /* OUT: End of parsed string */
 935 ){
 936   /* This function currently works by first transforming the UTF-16
 937   ** encoded string to UTF-8, then invoking sqlite3_prepare(). The
 938   ** tricky bit is figuring out the pointer to return in *pzTail.
 939   */
 940   char *zSql8;
 941   const char *zTail8 = 0;
 942   int rc = SQLITE_OK;
 943
 944 #ifdef SQLITE_ENABLE_API_ARMOR
 945   if( ppStmt==0 ) return SQLITE_MISUSE_BKPT;
 946 #endif
 947   *ppStmt = 0;
 948   if( !sqlite3SafetyCheckOk(db)||zSql==0 ){
 949     return SQLITE_MISUSE_BKPT;
 950   }
 951   if( nBytes>=0 ){
 952     int sz;
 953     const char *z = (const char*)zSql;
 954     for(sz=0; sz<nBytes && (z[sz]!=0 || z[sz+1]!=0); sz += 2){}
 955     nBytes = sz;
 956   }
 957   sqlite3_mutex_enter(db->mutex);
 958   zSql8 = sqlite3Utf16to8(db, zSql, nBytes, SQLITE_UTF16NATIVE);
 959   if( zSql8 ){
 960     rc = sqlite3LockAndPrepare(db, zSql8, -1, prepFlags, 0, ppStmt, &zTail8);
 961   }
 962
 963   if( zTail8 && pzTail ){
 964     /* If sqlite3_prepare returns a tail pointer, we calculate the
 965     ** equivalent pointer into the UTF-16 string by counting the unicode
 966     ** characters between zSql8 and zTail8, and then returning a pointer
 967     ** the same number of characters into the UTF-16 string.
 968     */
 969     int chars_parsed = sqlite3Utf8CharLen(zSql8, (int)(zTail8-zSql8));
 970     *pzTail = (u8 *)zSql + sqlite3Utf16ByteLen(zSql, chars_parsed);
 971   }
 972   sqlite3DbFree(db, zSql8);
 973   rc = sqlite3ApiExit(db, rc);
 974   sqlite3_mutex_leave(db->mutex);
 975   return rc;
 976 }
 977
 978 /*
 979 ** Two versions of the official API.  Legacy and new use.  In the legacy
 980 ** version, the original SQL text is not saved in the prepared statement
 981 ** and so if a schema change occurs, SQLITE_SCHEMA is returned by
 982 ** sqlite3_step().  In the new version, the original SQL text is retained
 983 ** and the statement is automatically recompiled if an schema change
 984 ** occurs.
 985 */
 986 int sqlite3_prepare16(
 987   sqlite3 *db,              /* Database handle. */
 988   const void *zSql,         /* UTF-16 encoded SQL statement. */
 989   int nBytes,               /* Length of zSql in bytes. */
 990   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
 991   const void **pzTail       /* OUT: End of parsed string */
 992 ){
 993   int rc;
 994   rc = sqlite3Prepare16(db,zSql,nBytes,0,ppStmt,pzTail);
 995   assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );  /* VERIFY: F13021 */
 996   return rc;
 997 }
 998 int sqlite3_prepare16_v2(
 999   sqlite3 *db,              /* Database handle. */
1000   const void *zSql,         /* UTF-16 encoded SQL statement. */
1001   int nBytes,               /* Length of zSql in bytes. */
1002   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
1003   const void **pzTail       /* OUT: End of parsed string */
1004 ){
1005   int rc;
1006   rc = sqlite3Prepare16(db,zSql,nBytes,SQLITE_PREPARE_SAVESQL,ppStmt,pzTail);
1007   assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );  /* VERIFY: F13021 */
1008   return rc;
1009 }
1010 int sqlite3_prepare16_v3(
1011   sqlite3 *db,              /* Database handle. */
1012   const void *zSql,         /* UTF-16 encoded SQL statement. */
1013   int nBytes,               /* Length of zSql in bytes. */
1014   unsigned int prepFlags,   /* Zero or more SQLITE_PREPARE_* flags */
1015   sqlite3_stmt **ppStmt,    /* OUT: A pointer to the prepared statement */
1016   const void **pzTail       /* OUT: End of parsed string */
1017 ){
1018   int rc;
1019   rc = sqlite3Prepare16(db,zSql,nBytes,
1020          SQLITE_PREPARE_SAVESQL|(prepFlags&SQLITE_PREPARE_MASK),
1021          ppStmt,pzTail);
1022   assert( rc==SQLITE_OK || ppStmt==0 || *ppStmt==0 );  /* VERIFY: F13021 */
1023   return rc;
1024 }
1025
1026 #endif /* SQLITE_OMIT_UTF16 */