src/attach.c

   1 /*
   2 ** 2003 April 6
   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 code used to implement the ATTACH and DETACH commands.
  13 */
  14 #include "sqliteInt.h"
  15
  16 #ifndef SQLITE_OMIT_ATTACH
  17 /*
  18 ** Resolve an expression that was part of an ATTACH or DETACH statement. This
  19 ** is slightly different from resolving a normal SQL expression, because simple
  20 ** identifiers are treated as strings, not possible column names or aliases.
  21 **
  22 ** i.e. if the parser sees:
  23 **
  24 **     ATTACH DATABASE abc AS def
  25 **
  26 ** it treats the two expressions as literal strings 'abc' and 'def' instead of
  27 ** looking for columns of the same name.
  28 **
  29 ** This only applies to the root node of pExpr, so the statement:
  30 **
  31 **     ATTACH DATABASE abc||def AS 'db2'
  32 **
  33 ** will fail because neither abc or def can be resolved.
  34 */
  35 static int resolveAttachExpr(NameContext *pName, Expr *pExpr)
  36 {
  37   int rc = SQLITE_OK;
  38   if( pExpr ){
  39     if( pExpr->op!=TK_ID ){
  40       rc = sqlite3ResolveExprNames(pName, pExpr);
  41       if( rc==SQLITE_OK && !sqlite3ExprIsConstant(pExpr) ){
  42         sqlite3ErrorMsg(pName->pParse, "invalid name: \"%s\"", pExpr->u.zToken);
  43         return SQLITE_ERROR;
  44       }
  45     }else{
  46       pExpr->op = TK_STRING;
  47     }
  48   }
  49   return rc;
  50 }
  51
  52 /*
  53 ** An SQL user-function registered to do the work of an ATTACH statement. The
  54 ** three arguments to the function come directly from an attach statement:
  55 **
  56 **     ATTACH DATABASE x AS y KEY z
  57 **
  58 **     SELECT sqlite_attach(x, y, z)
  59 **
  60 ** If the optional "KEY z" syntax is omitted, an SQL NULL is passed as the
  61 ** third argument.
  62 */
  63 static void attachFunc(
  64   sqlite3_context *context,
  65   int NotUsed,
  66   sqlite3_value **argv
  67 ){
  68   int i;
  69   int rc = 0;
  70   sqlite3 *db = sqlite3_context_db_handle(context);
  71   const char *zName;
  72   const char *zFile;
  73   char *zPath = 0;
  74   char *zErr = 0;
  75   unsigned int flags;
  76   Db *aNew;
  77   char *zErrDyn = 0;
  78   sqlite3_vfs *pVfs;
  79
  80   UNUSED_PARAMETER(NotUsed);
  81
  82   zFile = (const char *)sqlite3_value_text(argv[0]);
  83   zName = (const char *)sqlite3_value_text(argv[1]);
  84   if( zFile==0 ) zFile = "";
  85   if( zName==0 ) zName = "";
  86
  87   /* Check for the following errors:
  88   **
  89   **     * Too many attached databases,
  90   **     * Transaction currently open
  91   **     * Specified database name already being used.
  92   */
  93   if( db->nDb>=db->aLimit[SQLITE_LIMIT_ATTACHED]+2 ){
  94     zErrDyn = sqlite3MPrintf(db, "too many attached databases - max %d",
  95       db->aLimit[SQLITE_LIMIT_ATTACHED]
  96     );
  97     goto attach_error;
  98   }
  99   if( !db->autoCommit ){
 100     zErrDyn = sqlite3MPrintf(db, "cannot ATTACH database within transaction");
 101     goto attach_error;
 102   }
 103   for(i=0; i<db->nDb; i++){
 104     char *z = db->aDb[i].zName;
 105     assert( z && zName );
 106     if( sqlite3StrICmp(z, zName)==0 ){
 107       zErrDyn = sqlite3MPrintf(db, "database %s is already in use", zName);
 108       goto attach_error;
 109     }
 110   }
 111
 112   /* Allocate the new entry in the db->aDb[] array and initialise the schema
 113   ** hash tables.
 114   */
 115   if( db->aDb==db->aDbStatic ){
 116     aNew = sqlite3DbMallocRaw(db, sizeof(db->aDb[0])*3 );
 117     if( aNew==0 ) return;
 118     memcpy(aNew, db->aDb, sizeof(db->aDb[0])*2);
 119   }else{
 120     aNew = sqlite3DbRealloc(db, db->aDb, sizeof(db->aDb[0])*(db->nDb+1) );
 121     if( aNew==0 ) return;
 122   }
 123   db->aDb = aNew;
 124   aNew = &db->aDb[db->nDb];
 125   memset(aNew, 0, sizeof(*aNew));
 126
 127   /* Open the database file. If the btree is successfully opened, use
 128   ** it to obtain the database schema. At this point the schema may
 129   ** or may not be initialised.
 130   */
 131   flags = db->openFlags;
 132   rc = sqlite3ParseUri(db->pVfs->zName, zFile, &flags, &pVfs, &zPath, &zErr);
 133   if( rc!=SQLITE_OK ){
 134     if( rc==SQLITE_NOMEM ) db->mallocFailed = 1;
 135     sqlite3_result_error(context, zErr, -1);
 136     sqlite3_free(zErr);
 137     return;
 138   }
 139   assert( pVfs );
 140   flags |= SQLITE_OPEN_MAIN_DB;
 141   rc = sqlite3BtreeOpen(pVfs, zPath, db, &aNew->pBt, 0, flags);
 142   sqlite3_free( zPath );
 143   db->nDb++;
 144   if( rc==SQLITE_CONSTRAINT ){
 145     rc = SQLITE_ERROR;
 146     zErrDyn = sqlite3MPrintf(db, "database is already attached");
 147   }else if( rc==SQLITE_OK ){
 148     Pager *pPager;
 149     aNew->pSchema = sqlite3SchemaGet(db, aNew->pBt);
 150     if( !aNew->pSchema ){
 151       rc = SQLITE_NOMEM;
 152     }else if( aNew->pSchema->file_format && aNew->pSchema->enc!=ENC(db) ){
 153       zErrDyn = sqlite3MPrintf(db,
 154         "attached databases must use the same text encoding as main database");
 155       rc = SQLITE_ERROR;
 156     }
 157     pPager = sqlite3BtreePager(aNew->pBt);
 158     sqlite3PagerLockingMode(pPager, db->dfltLockMode);
 159     sqlite3BtreeSecureDelete(aNew->pBt,
 160                              sqlite3BtreeSecureDelete(db->aDb[0].pBt,-1) );
 161   }
 162   aNew->safety_level = 3;
 163   aNew->zName = sqlite3DbStrDup(db, zName);
 164   if( rc==SQLITE_OK && aNew->zName==0 ){
 165     rc = SQLITE_NOMEM;
 166   }
 167
 168
 169 #ifdef SQLITE_HAS_CODEC
 170   if( rc==SQLITE_OK ){
 171     extern int sqlite3CodecAttach(sqlite3*, int, const void*, int);
 172     extern void sqlite3CodecGetKey(sqlite3*, int, void**, int*);
 173     int nKey;
 174     char *zKey;
 175     int t = sqlite3_value_type(argv[2]);
 176     switch( t ){
 177       case SQLITE_INTEGER:
 178       case SQLITE_FLOAT:
 179         zErrDyn = sqlite3DbStrDup(db, "Invalid key value");
 180         rc = SQLITE_ERROR;
 181         break;
 182
 183       case SQLITE_TEXT:
 184       case SQLITE_BLOB:
 185         nKey = sqlite3_value_bytes(argv[2]);
 186         zKey = (char *)sqlite3_value_blob(argv[2]);
 187         rc = sqlite3CodecAttach(db, db->nDb-1, zKey, nKey);
 188         break;
 189
 190       case SQLITE_NULL:
 191         /* No key specified.  Use the key from the main database */
 192         sqlite3CodecGetKey(db, 0, (void**)&zKey, &nKey);
 193         if( nKey>0 || sqlite3BtreeGetReserve(db->aDb[0].pBt)>0 ){
 194           rc = sqlite3CodecAttach(db, db->nDb-1, zKey, nKey);
 195         }
 196         break;
 197     }
 198   }
 199 #endif
 200
 201   /* If the file was opened successfully, read the schema for the new database.
 202   ** If this fails, or if opening the file failed, then close the file and
 203   ** remove the entry from the db->aDb[] array. i.e. put everything back the way
 204   ** we found it.
 205   */
 206   if( rc==SQLITE_OK ){
 207     sqlite3BtreeEnterAll(db);
 208     rc = sqlite3Init(db, &zErrDyn);
 209     sqlite3BtreeLeaveAll(db);
 210   }
 211   if( rc ){
 212     int iDb = db->nDb - 1;
 213     assert( iDb>=2 );
 214     if( db->aDb[iDb].pBt ){
 215       sqlite3BtreeClose(db->aDb[iDb].pBt);
 216       db->aDb[iDb].pBt = 0;
 217       db->aDb[iDb].pSchema = 0;
 218     }
 219     sqlite3ResetAllSchemasOfConnection(db);
 220     db->nDb = iDb;
 221     if( rc==SQLITE_NOMEM || rc==SQLITE_IOERR_NOMEM ){
 222       db->mallocFailed = 1;
 223       sqlite3DbFree(db, zErrDyn);
 224       zErrDyn = sqlite3MPrintf(db, "out of memory");
 225     }else if( zErrDyn==0 ){
 226       zErrDyn = sqlite3MPrintf(db, "unable to open database: %s", zFile);
 227     }
 228     goto attach_error;
 229   }
 230
 231   return;
 232
 233 attach_error:
 234   /* Return an error if we get here */
 235   if( zErrDyn ){
 236     sqlite3_result_error(context, zErrDyn, -1);
 237     sqlite3DbFree(db, zErrDyn);
 238   }
 239   if( rc ) sqlite3_result_error_code(context, rc);
 240 }
 241
 242 /*
 243 ** An SQL user-function registered to do the work of an DETACH statement. The
 244 ** three arguments to the function come directly from a detach statement:
 245 **
 246 **     DETACH DATABASE x
 247 **
 248 **     SELECT sqlite_detach(x)
 249 */
 250 static void detachFunc(
 251   sqlite3_context *context,
 252   int NotUsed,
 253   sqlite3_value **argv
 254 ){
 255   const char *zName = (const char *)sqlite3_value_text(argv[0]);
 256   sqlite3 *db = sqlite3_context_db_handle(context);
 257   int i;
 258   Db *pDb = 0;
 259   char zErr[128];
 260
 261   UNUSED_PARAMETER(NotUsed);
 262
 263   if( zName==0 ) zName = "";
 264   for(i=0; i<db->nDb; i++){
 265     pDb = &db->aDb[i];
 266     if( pDb->pBt==0 ) continue;
 267     if( sqlite3StrICmp(pDb->zName, zName)==0 ) break;
 268   }
 269
 270   if( i>=db->nDb ){
 271     sqlite3_snprintf(sizeof(zErr),zErr, "no such database: %s", zName);
 272     goto detach_error;
 273   }
 274   if( i<2 ){
 275     sqlite3_snprintf(sizeof(zErr),zErr, "cannot detach database %s", zName);
 276     goto detach_error;
 277   }
 278   if( !db->autoCommit ){
 279     sqlite3_snprintf(sizeof(zErr), zErr,
 280                      "cannot DETACH database within transaction");
 281     goto detach_error;
 282   }
 283   if( sqlite3BtreeIsInReadTrans(pDb->pBt) || sqlite3BtreeIsInBackup(pDb->pBt) ){
 284     sqlite3_snprintf(sizeof(zErr),zErr, "database %s is locked", zName);
 285     goto detach_error;
 286   }
 287
 288   sqlite3BtreeClose(pDb->pBt);
 289   pDb->pBt = 0;
 290   pDb->pSchema = 0;
 291   sqlite3ResetAllSchemasOfConnection(db);
 292   return;
 293
 294 detach_error:
 295   sqlite3_result_error(context, zErr, -1);
 296 }
 297
 298 /*
 299 ** This procedure generates VDBE code for a single invocation of either the
 300 ** sqlite_detach() or sqlite_attach() SQL user functions.
 301 */
 302 static void codeAttach(
 303   Parse *pParse,       /* The parser context */
 304   int type,            /* Either SQLITE_ATTACH or SQLITE_DETACH */
 305   FuncDef const *pFunc,/* FuncDef wrapper for detachFunc() or attachFunc() */
 306   Expr *pAuthArg,      /* Expression to pass to authorization callback */
 307   Expr *pFilename,     /* Name of database file */
 308   Expr *pDbname,       /* Name of the database to use internally */
 309   Expr *pKey           /* Database key for encryption extension */
 310 ){
 311   int rc;
 312   NameContext sName;
 313   Vdbe *v;
 314   sqlite3* db = pParse->db;
 315   int regArgs;
 316
 317   memset(&sName, 0, sizeof(NameContext));
 318   sName.pParse = pParse;
 319
 320   if(
 321       SQLITE_OK!=(rc = resolveAttachExpr(&sName, pFilename)) ||
 322       SQLITE_OK!=(rc = resolveAttachExpr(&sName, pDbname)) ||
 323       SQLITE_OK!=(rc = resolveAttachExpr(&sName, pKey))
 324   ){
 325     pParse->nErr++;
 326     goto attach_end;
 327   }
 328
 329 #ifndef SQLITE_OMIT_AUTHORIZATION
 330   if( pAuthArg ){
 331     char *zAuthArg;
 332     if( pAuthArg->op==TK_STRING ){
 333       zAuthArg = pAuthArg->u.zToken;
 334     }else{
 335       zAuthArg = 0;
 336     }
 337     rc = sqlite3AuthCheck(pParse, type, zAuthArg, 0, 0);
 338     if(rc!=SQLITE_OK ){
 339       goto attach_end;
 340     }
 341   }
 342 #endif /* SQLITE_OMIT_AUTHORIZATION */
 343
 344
 345   v = sqlite3GetVdbe(pParse);
 346   regArgs = sqlite3GetTempRange(pParse, 4);
 347   sqlite3ExprCode(pParse, pFilename, regArgs);
 348   sqlite3ExprCode(pParse, pDbname, regArgs+1);
 349   sqlite3ExprCode(pParse, pKey, regArgs+2);
 350
 351   assert( v || db->mallocFailed );
 352   if( v ){
 353     sqlite3VdbeAddOp3(v, OP_Function, 0, regArgs+3-pFunc->nArg, regArgs+3);
 354     assert( pFunc->nArg==-1 || (pFunc->nArg&0xff)==pFunc->nArg );
 355     sqlite3VdbeChangeP5(v, (u8)(pFunc->nArg));
 356     sqlite3VdbeChangeP4(v, -1, (char *)pFunc, P4_FUNCDEF);
 357
 358     /* Code an OP_Expire. For an ATTACH statement, set P1 to true (expire this
 359     ** statement only). For DETACH, set it to false (expire all existing
 360     ** statements).
 361     */
 362     sqlite3VdbeAddOp1(v, OP_Expire, (type==SQLITE_ATTACH));
 363   }
 364
 365 attach_end:
 366   sqlite3ExprDelete(db, pFilename);
 367   sqlite3ExprDelete(db, pDbname);
 368   sqlite3ExprDelete(db, pKey);
 369 }
 370
 371 /*
 372 ** Called by the parser to compile a DETACH statement.
 373 **
 374 **     DETACH pDbname
 375 */
 376 void sqlite3Detach(Parse *pParse, Expr *pDbname){
 377   static const FuncDef detach_func = {
 378     1,                /* nArg */
 379     SQLITE_UTF8,      /* iPrefEnc */
 380     0,                /* flags */
 381     0,                /* pUserData */
 382     0,                /* pNext */
 383     detachFunc,       /* xFunc */
 384     0,                /* xStep */
 385     0,                /* xFinalize */
 386     "sqlite_detach",  /* zName */
 387     0,                /* pHash */
 388     0                 /* pDestructor */
 389   };
 390   codeAttach(pParse, SQLITE_DETACH, &detach_func, pDbname, 0, 0, pDbname);
 391 }
 392
 393 /*
 394 ** Called by the parser to compile an ATTACH statement.
 395 **
 396 **     ATTACH p AS pDbname KEY pKey
 397 */
 398 void sqlite3Attach(Parse *pParse, Expr *p, Expr *pDbname, Expr *pKey){
 399   static const FuncDef attach_func = {
 400     3,                /* nArg */
 401     SQLITE_UTF8,      /* iPrefEnc */
 402     0,                /* flags */
 403     0,                /* pUserData */
 404     0,                /* pNext */
 405     attachFunc,       /* xFunc */
 406     0,                /* xStep */
 407     0,                /* xFinalize */
 408     "sqlite_attach",  /* zName */
 409     0,                /* pHash */
 410     0                 /* pDestructor */
 411   };
 412   codeAttach(pParse, SQLITE_ATTACH, &attach_func, p, p, pDbname, pKey);
 413 }
 414 #endif /* SQLITE_OMIT_ATTACH */
 415
 416 /*
 417 ** Initialize a DbFixer structure.  This routine must be called prior
 418 ** to passing the structure to one of the sqliteFixAAAA() routines below.
 419 **
 420 ** The return value indicates whether or not fixation is required.  TRUE
 421 ** means we do need to fix the database references, FALSE means we do not.
 422 */
 423 int sqlite3FixInit(
 424   DbFixer *pFix,      /* The fixer to be initialized */
 425   Parse *pParse,      /* Error messages will be written here */
 426   int iDb,            /* This is the database that must be used */
 427   const char *zType,  /* "view", "trigger", or "index" */
 428   const Token *pName  /* Name of the view, trigger, or index */
 429 ){
 430   sqlite3 *db;
 431
 432   if( NEVER(iDb<0) || iDb==1 ) return 0;
 433   db = pParse->db;
 434   assert( db->nDb>iDb );
 435   pFix->pParse = pParse;
 436   pFix->zDb = db->aDb[iDb].zName;
 437   pFix->zType = zType;
 438   pFix->pName = pName;
 439   return 1;
 440 }
 441
 442 /*
 443 ** The following set of routines walk through the parse tree and assign
 444 ** a specific database to all table references where the database name
 445 ** was left unspecified in the original SQL statement.  The pFix structure
 446 ** must have been initialized by a prior call to sqlite3FixInit().
 447 **
 448 ** These routines are used to make sure that an index, trigger, or
 449 ** view in one database does not refer to objects in a different database.
 450 ** (Exception: indices, triggers, and views in the TEMP database are
 451 ** allowed to refer to anything.)  If a reference is explicitly made
 452 ** to an object in a different database, an error message is added to
 453 ** pParse->zErrMsg and these routines return non-zero.  If everything
 454 ** checks out, these routines return 0.
 455 */
 456 int sqlite3FixSrcList(
 457   DbFixer *pFix,       /* Context of the fixation */
 458   SrcList *pList       /* The Source list to check and modify */
 459 ){
 460   int i;
 461   const char *zDb;
 462   struct SrcList_item *pItem;
 463
 464   if( NEVER(pList==0) ) return 0;
 465   zDb = pFix->zDb;
 466   for(i=0, pItem=pList->a; i<pList->nSrc; i++, pItem++){
 467     if( pItem->zDatabase==0 ){
 468       pItem->zDatabase = sqlite3DbStrDup(pFix->pParse->db, zDb);
 469     }else if( sqlite3StrICmp(pItem->zDatabase,zDb)!=0 ){
 470       sqlite3ErrorMsg(pFix->pParse,
 471          "%s %T cannot reference objects in database %s",
 472          pFix->zType, pFix->pName, pItem->zDatabase);
 473       return 1;
 474     }
 475 #if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER)
 476     if( sqlite3FixSelect(pFix, pItem->pSelect) ) return 1;
 477     if( sqlite3FixExpr(pFix, pItem->pOn) ) return 1;
 478 #endif
 479   }
 480   return 0;
 481 }
 482 #if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER)
 483 int sqlite3FixSelect(
 484   DbFixer *pFix,       /* Context of the fixation */
 485   Select *pSelect      /* The SELECT statement to be fixed to one database */
 486 ){
 487   while( pSelect ){
 488     if( sqlite3FixExprList(pFix, pSelect->pEList) ){
 489       return 1;
 490     }
 491     if( sqlite3FixSrcList(pFix, pSelect->pSrc) ){
 492       return 1;
 493     }
 494     if( sqlite3FixExpr(pFix, pSelect->pWhere) ){
 495       return 1;
 496     }
 497     if( sqlite3FixExpr(pFix, pSelect->pHaving) ){
 498       return 1;
 499     }
 500     pSelect = pSelect->pPrior;
 501   }
 502   return 0;
 503 }
 504 int sqlite3FixExpr(
 505   DbFixer *pFix,     /* Context of the fixation */
 506   Expr *pExpr        /* The expression to be fixed to one database */
 507 ){
 508   while( pExpr ){
 509     if( ExprHasAnyProperty(pExpr, EP_TokenOnly) ) break;
 510     if( ExprHasProperty(pExpr, EP_xIsSelect) ){
 511       if( sqlite3FixSelect(pFix, pExpr->x.pSelect) ) return 1;
 512     }else{
 513       if( sqlite3FixExprList(pFix, pExpr->x.pList) ) return 1;
 514     }
 515     if( sqlite3FixExpr(pFix, pExpr->pRight) ){
 516       return 1;
 517     }
 518     pExpr = pExpr->pLeft;
 519   }
 520   return 0;
 521 }
 522 int sqlite3FixExprList(
 523   DbFixer *pFix,     /* Context of the fixation */
 524   ExprList *pList    /* The expression to be fixed to one database */
 525 ){
 526   int i;
 527   struct ExprList_item *pItem;
 528   if( pList==0 ) return 0;
 529   for(i=0, pItem=pList->a; i<pList->nExpr; i++, pItem++){
 530     if( sqlite3FixExpr(pFix, pItem->pExpr) ){
 531       return 1;
 532     }
 533   }
 534   return 0;
 535 }
 536 #endif
 537
 538 #ifndef SQLITE_OMIT_TRIGGER
 539 int sqlite3FixTriggerStep(
 540   DbFixer *pFix,     /* Context of the fixation */
 541   TriggerStep *pStep /* The trigger step be fixed to one database */
 542 ){
 543   while( pStep ){
 544     if( sqlite3FixSelect(pFix, pStep->pSelect) ){
 545       return 1;
 546     }
 547     if( sqlite3FixExpr(pFix, pStep->pWhere) ){
 548       return 1;
 549     }
 550     if( sqlite3FixExprList(pFix, pStep->pExprList) ){
 551       return 1;
 552     }
 553     pStep = pStep->pNext;
 554   }
 555   return 0;
 556 }
 557 #endif