src/test6.c

   1 /*
   2 ** 2004 May 22
   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 **
  13 ** This file contains code that modified the OS layer in order to simulate
  14 ** the effect on the database file of an OS crash or power failure.  This
  15 ** is used to test the ability of SQLite to recover from those situations.
  16 */
  17 #if SQLITE_TEST          /* This file is used for testing only */
  18 #include "sqliteInt.h"
  19 #include "tclsqlite.h"
  20
  21 #ifndef SQLITE_OMIT_DISKIO  /* This file is a no-op if disk I/O is disabled */
  22
  23 /* #define TRACE_CRASHTEST */
  24
  25 typedef struct CrashFile CrashFile;
  26 typedef struct CrashGlobal CrashGlobal;
  27 typedef struct WriteBuffer WriteBuffer;
  28
  29 /*
  30 ** Method:
  31 **
  32 **   This layer is implemented as a wrapper around the "real"
  33 **   sqlite3_file object for the host system. Each time data is
  34 **   written to the file object, instead of being written to the
  35 **   underlying file, the write operation is stored in an in-memory
  36 **   structure (type WriteBuffer). This structure is placed at the
  37 **   end of a global ordered list (the write-list).
  38 **
  39 **   When data is read from a file object, the requested region is
  40 **   first retrieved from the real file. The write-list is then
  41 **   traversed and data copied from any overlapping WriteBuffer
  42 **   structures to the output buffer. i.e. a read() operation following
  43 **   one or more write() operations works as expected, even if no
  44 **   data has actually been written out to the real file.
  45 **
  46 **   When a fsync() operation is performed, an operating system crash
  47 **   may be simulated, in which case exit(-1) is called (the call to
  48 **   xSync() never returns). Whether or not a crash is simulated,
  49 **   the data associated with a subset of the WriteBuffer structures
  50 **   stored in the write-list is written to the real underlying files
  51 **   and the entries removed from the write-list. If a crash is simulated,
  52 **   a subset of the buffers may be corrupted before the data is written.
  53 **
  54 **   The exact subset of the write-list written and/or corrupted is
  55 **   determined by the simulated device characteristics and sector-size.
  56 **
  57 ** "Normal" mode:
  58 **
  59 **   Normal mode is used when the simulated device has none of the
  60 **   SQLITE_IOCAP_XXX flags set.
  61 **
  62 **   In normal mode, if the fsync() is not a simulated crash, the
  63 **   write-list is traversed from beginning to end. Each WriteBuffer
  64 **   structure associated with the file handle used to call xSync()
  65 **   is written to the real file and removed from the write-list.
  66 **
  67 **   If a crash is simulated, one of the following takes place for
  68 **   each WriteBuffer in the write-list, regardless of which
  69 **   file-handle it is associated with:
  70 **
  71 **     1. The buffer is correctly written to the file, just as if
  72 **        a crash were not being simulated.
  73 **
  74 **     2. Nothing is done.
  75 **
  76 **     3. Garbage data is written to all sectors of the file that
  77 **        overlap the region specified by the WriteBuffer. Or garbage
  78 **        data is written to some contiguous section within the
  79 **        overlapped sectors.
  80 **
  81 ** Device Characteristic flag handling:
  82 **
  83 **   If the IOCAP_ATOMIC flag is set, then option (3) above is
  84 **   never selected.
  85 **
  86 **   If the IOCAP_ATOMIC512 flag is set, and the WriteBuffer represents
  87 **   an aligned write() of an integer number of 512 byte regions, then
  88 **   option (3) above is never selected. Instead, each 512 byte region
  89 **   is either correctly written or left completely untouched. Similar
  90 **   logic governs the behavior if any of the other ATOMICXXX flags
  91 **   is set.
  92 **
  93 **   If either the IOCAP_SAFEAPPEND or IOCAP_SEQUENTIAL flags are set
  94 **   and a crash is being simulated, then an entry of the write-list is
  95 **   selected at random. Everything in the list after the selected entry
  96 **   is discarded before processing begins.
  97 **
  98 **   If IOCAP_SEQUENTIAL is set and a crash is being simulated, option
  99 **   (1) is selected for all write-list entries except the last. If a
 100 **   crash is not being simulated, then all entries in the write-list
 101 **   that occur before at least one write() on the file-handle specified
 102 **   as part of the xSync() are written to their associated real files.
 103 **
 104 **   If IOCAP_SAFEAPPEND is set and the first byte written by the write()
 105 **   operation is one byte past the current end of the file, then option
 106 **   (1) is always selected.
 107 */
 108
 109 /*
 110 ** Each write operation in the write-list is represented by an instance
 111 ** of the following structure.
 112 **
 113 ** If zBuf is 0, then this structure represents a call to xTruncate(),
 114 ** not xWrite(). In that case, iOffset is the size that the file is
 115 ** truncated to.
 116 */
 117 struct WriteBuffer {
 118   i64 iOffset;                 /* Byte offset of the start of this write() */
 119   int nBuf;                    /* Number of bytes written */
 120   u8 *zBuf;                    /* Pointer to copy of written data */
 121   CrashFile *pFile;            /* File this write() applies to */
 122
 123   WriteBuffer *pNext;          /* Next in CrashGlobal.pWriteList */
 124 };
 125
 126 struct CrashFile {
 127   const sqlite3_io_methods *pMethod;   /* Must be first */
 128   sqlite3_file *pRealFile;             /* Underlying "real" file handle */
 129   char *zName;
 130   int flags;                           /* Flags the file was opened with */
 131
 132   /* Cache of the entire file. This is used to speed up OsRead() and
 133   ** OsFileSize() calls. Although both could be done by traversing the
 134   ** write-list, in practice this is impractically slow.
 135   */
 136   u8 *zData;                           /* Buffer containing file contents */
 137   int nData;                           /* Size of buffer allocated at zData */
 138   i64 iSize;                           /* Size of file in bytes */
 139 };
 140
 141 struct CrashGlobal {
 142   WriteBuffer *pWriteList;     /* Head of write-list */
 143   WriteBuffer *pWriteListEnd;  /* End of write-list */
 144
 145   int iSectorSize;             /* Value of simulated sector size */
 146   int iDeviceCharacteristics;  /* Value of simulated device characteristics */
 147
 148   int iCrash;                  /* Crash on the iCrash'th call to xSync() */
 149   char zCrashFile[500];        /* Crash during an xSync() on this file */
 150 };
 151
 152 static CrashGlobal g = {0, 0, SQLITE_DEFAULT_SECTOR_SIZE, 0, 0};
 153
 154 /*
 155 ** Set this global variable to 1 to enable crash testing.
 156 */
 157 static int sqlite3CrashTestEnable = 0;
 158
 159 static void *crash_malloc(int nByte){
 160   return (void *)Tcl_AttemptAlloc((size_t)nByte);
 161 }
 162 static void crash_free(void *p){
 163   Tcl_Free(p);
 164 }
 165 static void *crash_realloc(void *p, int n){
 166   return (void *)Tcl_AttemptRealloc(p, (size_t)n);
 167 }
 168
 169 /*
 170 ** Wrapper around the sqlite3OsWrite() function that avoids writing to the
 171 ** 512 byte block beginning at offset PENDING_BYTE.
 172 */
 173 static int writeDbFile(CrashFile *p, u8 *z, i64 iAmt, i64 iOff){
 174   int rc = SQLITE_OK;
 175   int iSkip = 0;
 176   if( (iAmt-iSkip)>0 ){
 177     rc = sqlite3OsWrite(p->pRealFile, &z[iSkip], (int)(iAmt-iSkip), iOff+iSkip);
 178   }
 179   return rc;
 180 }
 181
 182 /*
 183 ** Flush the write-list as if xSync() had been called on file handle
 184 ** pFile. If isCrash is true, simulate a crash.
 185 */
 186 static int writeListSync(CrashFile *pFile, int isCrash){
 187   int rc = SQLITE_OK;
 188   int iDc = g.iDeviceCharacteristics;
 189
 190   WriteBuffer *pWrite;
 191   WriteBuffer **ppPtr;
 192
 193   /* If this is not a crash simulation, set pFinal to point to the
 194   ** last element of the write-list that is associated with file handle
 195   ** pFile.
 196   **
 197   ** If this is a crash simulation, set pFinal to an arbitrarily selected
 198   ** element of the write-list.
 199   */
 200   WriteBuffer *pFinal = 0;
 201   if( !isCrash ){
 202     for(pWrite=g.pWriteList; pWrite; pWrite=pWrite->pNext){
 203       if( pWrite->pFile==pFile ){
 204         pFinal = pWrite;
 205       }
 206     }
 207   }else if( iDc&(SQLITE_IOCAP_SEQUENTIAL|SQLITE_IOCAP_SAFE_APPEND) ){
 208     int nWrite = 0;
 209     int iFinal;
 210     for(pWrite=g.pWriteList; pWrite; pWrite=pWrite->pNext) nWrite++;
 211     sqlite3_randomness(sizeof(int), &iFinal);
 212     iFinal = ((iFinal<0)?-1*iFinal:iFinal)%nWrite;
 213     for(pWrite=g.pWriteList; iFinal>0; pWrite=pWrite->pNext) iFinal--;
 214     pFinal = pWrite;
 215   }
 216
 217 #ifdef TRACE_CRASHTEST
 218   if( pFile ){
 219     printf("Sync %s (is %s crash)\n", pFile->zName, (isCrash?"a":"not a"));
 220   }
 221 #endif
 222
 223   ppPtr = &g.pWriteList;
 224   for(pWrite=*ppPtr; rc==SQLITE_OK && pWrite; pWrite=*ppPtr){
 225     sqlite3_file *pRealFile = pWrite->pFile->pRealFile;
 226
 227     /* (eAction==1)      -> write block out normally,
 228     ** (eAction==2)      -> do nothing,
 229     ** (eAction==3)      -> trash sectors.
 230     */
 231     int eAction = 0;
 232     if( !isCrash ){
 233       eAction = 2;
 234       if( (pWrite->pFile==pFile || iDc&SQLITE_IOCAP_SEQUENTIAL) ){
 235         eAction = 1;
 236       }
 237     }else{
 238       char random;
 239       sqlite3_randomness(1, &random);
 240
 241       /* Do not select option 3 (sector trashing) if the IOCAP_ATOMIC flag
 242       ** is set or this is an OsTruncate(), not an Oswrite().
 243       */
 244       if( (iDc&SQLITE_IOCAP_ATOMIC) || (pWrite->zBuf==0) ){
 245         random &= 0x01;
 246       }
 247
 248       /* If IOCAP_SEQUENTIAL is set and this is not the final entry
 249       ** in the truncated write-list, always select option 1 (write
 250       ** out correctly).
 251       */
 252       if( (iDc&SQLITE_IOCAP_SEQUENTIAL && pWrite!=pFinal) ){
 253         random = 0;
 254       }
 255
 256       /* If IOCAP_SAFE_APPEND is set and this OsWrite() operation is
 257       ** an append (first byte of the written region is 1 byte past the
 258       ** current EOF), always select option 1 (write out correctly).
 259       */
 260       if( iDc&SQLITE_IOCAP_SAFE_APPEND && pWrite->zBuf ){
 261         i64 iSize;
 262         sqlite3OsFileSize(pRealFile, &iSize);
 263         if( iSize==pWrite->iOffset ){
 264           random = 0;
 265         }
 266       }
 267
 268       if( (random&0x06)==0x06 ){
 269         eAction = 3;
 270       }else{
 271         eAction = ((random&0x01)?2:1);
 272       }
 273     }
 274
 275     switch( eAction ){
 276       case 1: {               /* Write out correctly */
 277         if( pWrite->zBuf ){
 278           rc = writeDbFile(
 279               pWrite->pFile, pWrite->zBuf, pWrite->nBuf, pWrite->iOffset
 280           );
 281         }else{
 282           rc = sqlite3OsTruncate(pRealFile, pWrite->iOffset);
 283         }
 284         *ppPtr = pWrite->pNext;
 285 #ifdef TRACE_CRASHTEST
 286         if( isCrash ){
 287           printf("Writing %d bytes @ %d (%s)\n",
 288             pWrite->nBuf, (int)pWrite->iOffset, pWrite->pFile->zName
 289           );
 290         }
 291 #endif
 292         crash_free(pWrite);
 293         break;
 294       }
 295       case 2: {               /* Do nothing */
 296         ppPtr = &pWrite->pNext;
 297 #ifdef TRACE_CRASHTEST
 298         if( isCrash ){
 299           printf("Omiting %d bytes @ %d (%s)\n",
 300             pWrite->nBuf, (int)pWrite->iOffset, pWrite->pFile->zName
 301           );
 302         }
 303 #endif
 304         break;
 305       }
 306       case 3: {               /* Trash sectors */
 307         u8 *zGarbage;
 308         int iFirst = (int)(pWrite->iOffset/g.iSectorSize);
 309         int iLast = (int)((pWrite->iOffset+pWrite->nBuf-1)/g.iSectorSize);
 310
 311         assert(pWrite->zBuf);
 312
 313 #ifdef TRACE_CRASHTEST
 314         printf("Trashing %d sectors (%d bytes) @ %lld (sector %d) (%s)\n",
 315             1+iLast-iFirst, (1+iLast-iFirst)*g.iSectorSize,
 316             pWrite->iOffset, iFirst, pWrite->pFile->zName
 317         );
 318 #endif
 319
 320         zGarbage = crash_malloc(g.iSectorSize);
 321         if( zGarbage ){
 322           sqlite3_int64 i;
 323           for(i=iFirst; rc==SQLITE_OK && i<=iLast; i++){
 324             sqlite3_randomness(g.iSectorSize, zGarbage);
 325             rc = writeDbFile(
 326               pWrite->pFile, zGarbage, g.iSectorSize, i*g.iSectorSize
 327             );
 328           }
 329           crash_free(zGarbage);
 330         }else{
 331           rc = SQLITE_NOMEM;
 332         }
 333
 334         ppPtr = &pWrite->pNext;
 335         break;
 336       }
 337
 338       default:
 339         assert(!"Cannot happen");
 340     }
 341
 342     if( pWrite==pFinal ) break;
 343   }
 344
 345   if( rc==SQLITE_OK && isCrash ){
 346     exit(-1);
 347   }
 348
 349   for(pWrite=g.pWriteList; pWrite && pWrite->pNext; pWrite=pWrite->pNext);
 350   g.pWriteListEnd = pWrite;
 351
 352   return rc;
 353 }
 354
 355 /*
 356 ** Add an entry to the end of the write-list.
 357 */
 358 static int writeListAppend(
 359   sqlite3_file *pFile,
 360   sqlite3_int64 iOffset,
 361   const u8 *zBuf,
 362   int nBuf
 363 ){
 364   WriteBuffer *pNew;
 365
 366   assert((zBuf && nBuf) || (!nBuf && !zBuf));
 367
 368   pNew = (WriteBuffer *)crash_malloc(sizeof(WriteBuffer) + nBuf);
 369   if( pNew==0 ){
 370     fprintf(stderr, "out of memory in the crash simulator\n");
 371   }
 372   memset(pNew, 0, sizeof(WriteBuffer)+nBuf);
 373   pNew->iOffset = iOffset;
 374   pNew->nBuf = nBuf;
 375   pNew->pFile = (CrashFile *)pFile;
 376   if( zBuf ){
 377     pNew->zBuf = (u8 *)&pNew[1];
 378     memcpy(pNew->zBuf, zBuf, nBuf);
 379   }
 380
 381   if( g.pWriteList ){
 382     assert(g.pWriteListEnd);
 383     g.pWriteListEnd->pNext = pNew;
 384   }else{
 385     g.pWriteList = pNew;
 386   }
 387   g.pWriteListEnd = pNew;
 388
 389   return SQLITE_OK;
 390 }
 391
 392 /*
 393 ** Close a crash-file.
 394 */
 395 static int cfClose(sqlite3_file *pFile){
 396   CrashFile *pCrash = (CrashFile *)pFile;
 397   writeListSync(pCrash, 0);
 398   sqlite3OsClose(pCrash->pRealFile);
 399   return SQLITE_OK;
 400 }
 401
 402 /*
 403 ** Read data from a crash-file.
 404 */
 405 static int cfRead(
 406   sqlite3_file *pFile,
 407   void *zBuf,
 408   int iAmt,
 409   sqlite_int64 iOfst
 410 ){
 411   CrashFile *pCrash = (CrashFile *)pFile;
 412   int nCopy = (int)MIN((i64)iAmt, (pCrash->iSize - iOfst));
 413
 414   if( nCopy>0 ){
 415     memcpy(zBuf, &pCrash->zData[iOfst], nCopy);
 416   }
 417
 418   /* Check the file-size to see if this is a short-read */
 419   if( nCopy<iAmt ){
 420     return SQLITE_IOERR_SHORT_READ;
 421   }
 422
 423   return SQLITE_OK;
 424 }
 425
 426 /*
 427 ** Write data to a crash-file.
 428 */
 429 static int cfWrite(
 430   sqlite3_file *pFile,
 431   const void *zBuf,
 432   int iAmt,
 433   sqlite_int64 iOfst
 434 ){
 435   CrashFile *pCrash = (CrashFile *)pFile;
 436   if( iAmt+iOfst>pCrash->iSize ){
 437     pCrash->iSize = (int)(iAmt+iOfst);
 438   }
 439   while( pCrash->iSize>pCrash->nData ){
 440     u8 *zNew;
 441     int nNew = (pCrash->nData*2) + 4096;
 442     zNew = crash_realloc(pCrash->zData, nNew);
 443     if( !zNew ){
 444       return SQLITE_NOMEM;
 445     }
 446     memset(&zNew[pCrash->nData], 0, nNew-pCrash->nData);
 447     pCrash->nData = nNew;
 448     pCrash->zData = zNew;
 449   }
 450   memcpy(&pCrash->zData[iOfst], zBuf, iAmt);
 451   return writeListAppend(pFile, iOfst, zBuf, iAmt);
 452 }
 453
 454 /*
 455 ** Truncate a crash-file.
 456 */
 457 static int cfTruncate(sqlite3_file *pFile, sqlite_int64 size){
 458   CrashFile *pCrash = (CrashFile *)pFile;
 459   assert(size>=0);
 460   if( pCrash->iSize>size ){
 461     pCrash->iSize = (int)size;
 462   }
 463   return writeListAppend(pFile, size, 0, 0);
 464 }
 465
 466 /*
 467 ** Sync a crash-file.
 468 */
 469 static int cfSync(sqlite3_file *pFile, int flags){
 470   CrashFile *pCrash = (CrashFile *)pFile;
 471   int isCrash = 0;
 472
 473   const char *zName = pCrash->zName;
 474   const char *zCrashFile = g.zCrashFile;
 475   int nName = (int)strlen(zName);
 476   int nCrashFile = (int)strlen(zCrashFile);
 477
 478   if( nCrashFile>0 && zCrashFile[nCrashFile-1]=='*' ){
 479     nCrashFile--;
 480     if( nName>nCrashFile ) nName = nCrashFile;
 481   }
 482
 483 #ifdef TRACE_CRASHTEST
 484   printf("cfSync(): nName = %d, nCrashFile = %d, zName = %s, zCrashFile = %s\n",
 485          nName, nCrashFile, zName, zCrashFile);
 486 #endif
 487
 488   if( nName==nCrashFile && 0==memcmp(zName, zCrashFile, nName) ){
 489 #ifdef TRACE_CRASHTEST
 490     printf("cfSync(): name matched, g.iCrash = %d\n", g.iCrash);
 491 #endif
 492     if( (--g.iCrash)==0 ) isCrash = 1;
 493   }
 494
 495   return writeListSync(pCrash, isCrash);
 496 }
 497
 498 /*
 499 ** Return the current file-size of the crash-file.
 500 */
 501 static int cfFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){
 502   CrashFile *pCrash = (CrashFile *)pFile;
 503   *pSize = (i64)pCrash->iSize;
 504   return SQLITE_OK;
 505 }
 506
 507 /*
 508 ** Calls related to file-locks are passed on to the real file handle.
 509 */
 510 static int cfLock(sqlite3_file *pFile, int eLock){
 511   return sqlite3OsLock(((CrashFile *)pFile)->pRealFile, eLock);
 512 }
 513 static int cfUnlock(sqlite3_file *pFile, int eLock){
 514   return sqlite3OsUnlock(((CrashFile *)pFile)->pRealFile, eLock);
 515 }
 516 static int cfCheckReservedLock(sqlite3_file *pFile, int *pResOut){
 517   return sqlite3OsCheckReservedLock(((CrashFile *)pFile)->pRealFile, pResOut);
 518 }
 519 static int cfFileControl(sqlite3_file *pFile, int op, void *pArg){
 520   if( op==SQLITE_FCNTL_SIZE_HINT ){
 521     CrashFile *pCrash = (CrashFile *)pFile;
 522     i64 nByte = *(i64 *)pArg;
 523     if( nByte>pCrash->iSize ){
 524       if( SQLITE_OK==writeListAppend(pFile, nByte, 0, 0) ){
 525         pCrash->iSize = (int)nByte;
 526       }
 527     }
 528     return SQLITE_OK;
 529   }
 530   return sqlite3OsFileControl(((CrashFile *)pFile)->pRealFile, op, pArg);
 531 }
 532
 533 /*
 534 ** The xSectorSize() and xDeviceCharacteristics() functions return
 535 ** the global values configured by the [sqlite_crashparams] tcl
 536 *  interface.
 537 */
 538 static int cfSectorSize(sqlite3_file *pFile){
 539   return g.iSectorSize;
 540 }
 541 static int cfDeviceCharacteristics(sqlite3_file *pFile){
 542   return g.iDeviceCharacteristics;
 543 }
 544
 545 /*
 546 ** Pass-throughs for WAL support.
 547 */
 548 static int cfShmLock(sqlite3_file *pFile, int ofst, int n, int flags){
 549   sqlite3_file *pReal = ((CrashFile*)pFile)->pRealFile;
 550   return pReal->pMethods->xShmLock(pReal, ofst, n, flags);
 551 }
 552 static void cfShmBarrier(sqlite3_file *pFile){
 553   sqlite3_file *pReal = ((CrashFile*)pFile)->pRealFile;
 554   pReal->pMethods->xShmBarrier(pReal);
 555 }
 556 static int cfShmUnmap(sqlite3_file *pFile, int delFlag){
 557   sqlite3_file *pReal = ((CrashFile*)pFile)->pRealFile;
 558   return pReal->pMethods->xShmUnmap(pReal, delFlag);
 559 }
 560 static int cfShmMap(
 561   sqlite3_file *pFile,            /* Handle open on database file */
 562   int iRegion,                    /* Region to retrieve */
 563   int sz,                         /* Size of regions */
 564   int w,                          /* True to extend file if necessary */
 565   void volatile **pp              /* OUT: Mapped memory */
 566 ){
 567   sqlite3_file *pReal = ((CrashFile*)pFile)->pRealFile;
 568   return pReal->pMethods->xShmMap(pReal, iRegion, sz, w, pp);
 569 }
 570
 571 static const sqlite3_io_methods CrashFileVtab = {
 572   2,                            /* iVersion */
 573   cfClose,                      /* xClose */
 574   cfRead,                       /* xRead */
 575   cfWrite,                      /* xWrite */
 576   cfTruncate,                   /* xTruncate */
 577   cfSync,                       /* xSync */
 578   cfFileSize,                   /* xFileSize */
 579   cfLock,                       /* xLock */
 580   cfUnlock,                     /* xUnlock */
 581   cfCheckReservedLock,          /* xCheckReservedLock */
 582   cfFileControl,                /* xFileControl */
 583   cfSectorSize,                 /* xSectorSize */
 584   cfDeviceCharacteristics,      /* xDeviceCharacteristics */
 585   cfShmMap,                     /* xShmMap */
 586   cfShmLock,                    /* xShmLock */
 587   cfShmBarrier,                 /* xShmBarrier */
 588   cfShmUnmap                    /* xShmUnmap */
 589 };
 590
 591 /*
 592 ** Application data for the crash VFS
 593 */
 594 struct crashAppData {
 595   sqlite3_vfs *pOrig;                   /* Wrapped vfs structure */
 596 };
 597
 598 /*
 599 ** Open a crash-file file handle.
 600 **
 601 ** The caller will have allocated pVfs->szOsFile bytes of space
 602 ** at pFile. This file uses this space for the CrashFile structure
 603 ** and allocates space for the "real" file structure using
 604 ** sqlite3_malloc(). The assumption here is (pVfs->szOsFile) is
 605 ** equal or greater than sizeof(CrashFile).
 606 */
 607 static int cfOpen(
 608   sqlite3_vfs *pCfVfs,
 609   const char *zName,
 610   sqlite3_file *pFile,
 611   int flags,
 612   int *pOutFlags
 613 ){
 614   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 615   int rc;
 616   CrashFile *pWrapper = (CrashFile *)pFile;
 617   sqlite3_file *pReal = (sqlite3_file*)&pWrapper[1];
 618
 619   memset(pWrapper, 0, sizeof(CrashFile));
 620   rc = sqlite3OsOpen(pVfs, zName, pReal, flags, pOutFlags);
 621
 622   if( rc==SQLITE_OK ){
 623     i64 iSize;
 624     pWrapper->pMethod = &CrashFileVtab;
 625     pWrapper->zName = (char *)zName;
 626     pWrapper->pRealFile = pReal;
 627     rc = sqlite3OsFileSize(pReal, &iSize);
 628     pWrapper->iSize = (int)iSize;
 629     pWrapper->flags = flags;
 630   }
 631   if( rc==SQLITE_OK ){
 632     pWrapper->nData = (int)(4096 + pWrapper->iSize);
 633     pWrapper->zData = crash_malloc(pWrapper->nData);
 634     if( pWrapper->zData ){
 635       /* os_unix.c contains an assert() that fails if the caller attempts
 636       ** to read data from the 512-byte locking region of a file opened
 637       ** with the SQLITE_OPEN_MAIN_DB flag. This region of a database file
 638       ** never contains valid data anyhow. So avoid doing such a read here.
 639       **
 640       ** UPDATE: It also contains an assert() verifying that each call
 641       ** to the xRead() method reads less than 128KB of data.
 642       */
 643       i64 iOff;
 644
 645       memset(pWrapper->zData, 0, pWrapper->nData);
 646       for(iOff=0; iOff<pWrapper->iSize; iOff += 512){
 647         int nRead = (int)(pWrapper->iSize - iOff);
 648         if( nRead>512 ) nRead = 512;
 649         rc = sqlite3OsRead(pReal, &pWrapper->zData[iOff], nRead, iOff);
 650       }
 651     }else{
 652       rc = SQLITE_NOMEM;
 653     }
 654   }
 655   if( rc!=SQLITE_OK && pWrapper->pMethod ){
 656     sqlite3OsClose(pFile);
 657   }
 658   return rc;
 659 }
 660
 661 static int cfDelete(sqlite3_vfs *pCfVfs, const char *zPath, int dirSync){
 662   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 663   return pVfs->xDelete(pVfs, zPath, dirSync);
 664 }
 665 static int cfAccess(
 666   sqlite3_vfs *pCfVfs,
 667   const char *zPath,
 668   int flags,
 669   int *pResOut
 670 ){
 671   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 672   return pVfs->xAccess(pVfs, zPath, flags, pResOut);
 673 }
 674 static int cfFullPathname(
 675   sqlite3_vfs *pCfVfs,
 676   const char *zPath,
 677   int nPathOut,
 678   char *zPathOut
 679 ){
 680   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 681   return pVfs->xFullPathname(pVfs, zPath, nPathOut, zPathOut);
 682 }
 683 static void *cfDlOpen(sqlite3_vfs *pCfVfs, const char *zPath){
 684   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 685   return pVfs->xDlOpen(pVfs, zPath);
 686 }
 687 static void cfDlError(sqlite3_vfs *pCfVfs, int nByte, char *zErrMsg){
 688   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 689   pVfs->xDlError(pVfs, nByte, zErrMsg);
 690 }
 691 static void (*cfDlSym(sqlite3_vfs *pCfVfs, void *pH, const char *zSym))(void){
 692   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 693   return pVfs->xDlSym(pVfs, pH, zSym);
 694 }
 695 static void cfDlClose(sqlite3_vfs *pCfVfs, void *pHandle){
 696   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 697   pVfs->xDlClose(pVfs, pHandle);
 698 }
 699 static int cfRandomness(sqlite3_vfs *pCfVfs, int nByte, char *zBufOut){
 700   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 701   return pVfs->xRandomness(pVfs, nByte, zBufOut);
 702 }
 703 static int cfSleep(sqlite3_vfs *pCfVfs, int nMicro){
 704   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 705   return pVfs->xSleep(pVfs, nMicro);
 706 }
 707 static int cfCurrentTime(sqlite3_vfs *pCfVfs, double *pTimeOut){
 708   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 709   return pVfs->xCurrentTime(pVfs, pTimeOut);
 710 }
 711 static int cfGetLastError(sqlite3_vfs *pCfVfs, int n, char *z){
 712   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 713   return pVfs->xGetLastError(pVfs, n, z);
 714 }
 715
 716 static int processDevSymArgs(
 717   Tcl_Interp *interp,
 718   int objc,
 719   Tcl_Obj *CONST objv[],
 720   int *piDeviceChar,
 721   int *piSectorSize
 722 ){
 723   struct DeviceFlag {
 724     char *zName;
 725     int iValue;
 726   } aFlag[] = {
 727     { "atomic",              SQLITE_IOCAP_ATOMIC                },
 728     { "atomic512",           SQLITE_IOCAP_ATOMIC512             },
 729     { "atomic1k",            SQLITE_IOCAP_ATOMIC1K              },
 730     { "atomic2k",            SQLITE_IOCAP_ATOMIC2K              },
 731     { "atomic4k",            SQLITE_IOCAP_ATOMIC4K              },
 732     { "atomic8k",            SQLITE_IOCAP_ATOMIC8K              },
 733     { "atomic16k",           SQLITE_IOCAP_ATOMIC16K             },
 734     { "atomic32k",           SQLITE_IOCAP_ATOMIC32K             },
 735     { "atomic64k",           SQLITE_IOCAP_ATOMIC64K             },
 736     { "sequential",          SQLITE_IOCAP_SEQUENTIAL            },
 737     { "safe_append",         SQLITE_IOCAP_SAFE_APPEND           },
 738     { "powersafe_overwrite", SQLITE_IOCAP_POWERSAFE_OVERWRITE   },
 739     { "batch-atomic",        SQLITE_IOCAP_BATCH_ATOMIC          },
 740     { 0, 0 }
 741   };
 742
 743   int i;
 744   int iDc = 0;
 745   int iSectorSize = 0;
 746   int setSectorsize = 0;
 747   int setDeviceChar = 0;
 748
 749   for(i=0; i<objc; i+=2){
 750     Tcl_Size nOpt;
 751     char *zOpt = Tcl_GetStringFromObj(objv[i], &nOpt);
 752
 753     if( (nOpt>11 || nOpt<2 || strncmp("-sectorsize", zOpt, nOpt))
 754      && (nOpt>16 || nOpt<2 || strncmp("-characteristics", zOpt, nOpt))
 755     ){
 756       Tcl_AppendResult(interp,
 757         "Bad option: \"", zOpt,
 758         "\" - must be \"-characteristics\" or \"-sectorsize\"", 0
 759       );
 760       return TCL_ERROR;
 761     }
 762     if( i==objc-1 ){
 763       Tcl_AppendResult(interp, "Option requires an argument: \"", zOpt, "\"",0);
 764       return TCL_ERROR;
 765     }
 766
 767     if( zOpt[1]=='s' ){
 768       if( Tcl_GetIntFromObj(interp, objv[i+1], &iSectorSize) ){
 769         return TCL_ERROR;
 770       }
 771       setSectorsize = 1;
 772     }else{
 773       int j;
 774       Tcl_Obj **apObj;
 775       Tcl_Size nObj;
 776       if( Tcl_ListObjGetElements(interp, objv[i+1], &nObj, &apObj) ){
 777         return TCL_ERROR;
 778       }
 779       for(j=0; j<(int)nObj; j++){
 780         int rc;
 781         int iChoice;
 782         Tcl_Obj *pFlag = Tcl_DuplicateObj(apObj[j]);
 783         Tcl_IncrRefCount(pFlag);
 784         Tcl_UtfToLower(Tcl_GetString(pFlag));
 785
 786         rc = Tcl_GetIndexFromObjStruct(
 787             interp, pFlag, aFlag, sizeof(aFlag[0]), "no such flag", 0, &iChoice
 788         );
 789         Tcl_DecrRefCount(pFlag);
 790         if( rc ){
 791           return TCL_ERROR;
 792         }
 793
 794         iDc |= aFlag[iChoice].iValue;
 795       }
 796       setDeviceChar = 1;
 797     }
 798   }
 799
 800   if( setDeviceChar ){
 801     *piDeviceChar = iDc;
 802   }
 803   if( setSectorsize ){
 804     *piSectorSize = iSectorSize;
 805   }
 806
 807   return TCL_OK;
 808 }
 809
 810 /*
 811 ** tclcmd:   sqlite3_crash_now
 812 **
 813 ** Simulate a crash immediately. This function does not return
 814 ** (writeListSync() calls exit(-1)).
 815 */
 816 static int SQLITE_TCLAPI crashNowCmd(
 817   void * clientData,
 818   Tcl_Interp *interp,
 819   int objc,
 820   Tcl_Obj *CONST objv[]
 821 ){
 822   if( objc!=1 ){
 823     Tcl_WrongNumArgs(interp, 1, objv, "");
 824     return TCL_ERROR;
 825   }
 826   writeListSync(0, 1);
 827   assert( 0 );
 828   return TCL_OK;
 829 }
 830
 831 /*
 832 ** tclcmd:   sqlite_crash_enable ENABLE ?DEFAULT?
 833 **
 834 ** Parameter ENABLE must be a boolean value. If true, then the "crash"
 835 ** vfs is added to the system. If false, it is removed.
 836 */
 837 static int SQLITE_TCLAPI crashEnableCmd(
 838   void * clientData,
 839   Tcl_Interp *interp,
 840   int objc,
 841   Tcl_Obj *CONST objv[]
 842 ){
 843   int isEnable;
 844   int isDefault = 0;
 845   static sqlite3_vfs crashVfs = {
 846     2,                  /* iVersion */
 847     0,                  /* szOsFile */
 848     0,                  /* mxPathname */
 849     0,                  /* pNext */
 850     "crash",            /* zName */
 851     0,                  /* pAppData */
 852
 853     cfOpen,               /* xOpen */
 854     cfDelete,             /* xDelete */
 855     cfAccess,             /* xAccess */
 856     cfFullPathname,       /* xFullPathname */
 857     cfDlOpen,             /* xDlOpen */
 858     cfDlError,            /* xDlError */
 859     cfDlSym,              /* xDlSym */
 860     cfDlClose,            /* xDlClose */
 861     cfRandomness,         /* xRandomness */
 862     cfSleep,              /* xSleep */
 863     cfCurrentTime,        /* xCurrentTime */
 864     cfGetLastError,       /* xGetLastError */
 865     0,                    /* xCurrentTimeInt64 */
 866   };
 867
 868   if( objc!=2 && objc!=3 ){
 869     Tcl_WrongNumArgs(interp, 1, objv, "ENABLE ?DEFAULT?");
 870     return TCL_ERROR;
 871   }
 872
 873   if( Tcl_GetBooleanFromObj(interp, objv[1], &isEnable) ){
 874     return TCL_ERROR;
 875   }
 876   if( objc==3 && Tcl_GetBooleanFromObj(interp, objv[2], &isDefault) ){
 877     return TCL_ERROR;
 878   }
 879
 880   if( (isEnable && crashVfs.pAppData) || (!isEnable && !crashVfs.pAppData) ){
 881     return TCL_OK;
 882   }
 883
 884   if( crashVfs.pAppData==0 ){
 885     sqlite3_vfs *pOriginalVfs = sqlite3_vfs_find(0);
 886     crashVfs.mxPathname = pOriginalVfs->mxPathname;
 887     crashVfs.pAppData = (void *)pOriginalVfs;
 888     crashVfs.szOsFile = sizeof(CrashFile) + pOriginalVfs->szOsFile;
 889     sqlite3_vfs_register(&crashVfs, isDefault);
 890   }else{
 891     crashVfs.pAppData = 0;
 892     sqlite3_vfs_unregister(&crashVfs);
 893   }
 894
 895   return TCL_OK;
 896 }
 897
 898 /*
 899 ** tclcmd:   sqlite_crashparams ?OPTIONS? DELAY CRASHFILE
 900 **
 901 ** This procedure implements a TCL command that enables crash testing
 902 ** in testfixture.  Once enabled, crash testing cannot be disabled.
 903 **
 904 ** Available options are "-characteristics" and "-sectorsize". Both require
 905 ** an argument. For -sectorsize, this is the simulated sector size in
 906 ** bytes. For -characteristics, the argument must be a list of io-capability
 907 ** flags to simulate. Valid flags are "atomic", "atomic512", "atomic1K",
 908 ** "atomic2K", "atomic4K", "atomic8K", "atomic16K", "atomic32K",
 909 ** "atomic64K", "sequential" and "safe_append".
 910 **
 911 ** Example:
 912 **
 913 **   sqlite_crashparams -sect 1024 -char {atomic sequential} ./test.db 1
 914 **
 915 */
 916 static int SQLITE_TCLAPI crashParamsObjCmd(
 917   void * clientData,
 918   Tcl_Interp *interp,
 919   int objc,
 920   Tcl_Obj *CONST objv[]
 921 ){
 922   int iDelay;
 923   const char *zCrashFile;
 924   Tcl_Size nCrashFile;
 925   int iDc, iSectorSize;
 926
 927   iDc = -1;
 928   iSectorSize = -1;
 929
 930   if( objc<3 ){
 931     Tcl_WrongNumArgs(interp, 1, objv, "?OPTIONS? DELAY CRASHFILE");
 932     goto error;
 933   }
 934
 935   zCrashFile = Tcl_GetStringFromObj(objv[objc-1], &nCrashFile);
 936   if( nCrashFile>=sizeof(g.zCrashFile) ){
 937     Tcl_AppendResult(interp, "Filename is too long: \"", zCrashFile, "\"", 0);
 938     goto error;
 939   }
 940   if( Tcl_GetIntFromObj(interp, objv[objc-2], &iDelay) ){
 941     goto error;
 942   }
 943
 944   if( processDevSymArgs(interp, objc-3, &objv[1], &iDc, &iSectorSize) ){
 945     return TCL_ERROR;
 946   }
 947
 948   if( iDc>=0 ){
 949     g.iDeviceCharacteristics = iDc;
 950   }
 951   if( iSectorSize>=0 ){
 952     g.iSectorSize = iSectorSize;
 953   }
 954
 955   g.iCrash = iDelay;
 956   memcpy(g.zCrashFile, zCrashFile, nCrashFile+1);
 957   sqlite3CrashTestEnable = 1;
 958   return TCL_OK;
 959
 960 error:
 961   return TCL_ERROR;
 962 }
 963
 964 static int SQLITE_TCLAPI devSymObjCmd(
 965   void * clientData,
 966   Tcl_Interp *interp,
 967   int objc,
 968   Tcl_Obj *CONST objv[]
 969 ){
 970   void devsym_register(int iDeviceChar, int iSectorSize);
 971
 972   int iDc = -1;
 973   int iSectorSize = -1;
 974
 975   if( processDevSymArgs(interp, objc-1, &objv[1], &iDc, &iSectorSize) ){
 976     return TCL_ERROR;
 977   }
 978   devsym_register(iDc, iSectorSize);
 979
 980   return TCL_OK;
 981 }
 982
 983 /*
 984 ** tclcmd: sqlite3_crash_on_write N
 985 */
 986 static int SQLITE_TCLAPI writeCrashObjCmd(
 987   void * clientData,
 988   Tcl_Interp *interp,
 989   int objc,
 990   Tcl_Obj *CONST objv[]
 991 ){
 992   void devsym_crash_on_write(int);
 993   int nWrite = 0;
 994
 995   if( objc!=2 ){
 996     Tcl_WrongNumArgs(interp, 1, objv, "NWRITE");
 997     return TCL_ERROR;
 998   }
 999   if( Tcl_GetIntFromObj(interp, objv[1], &nWrite) ){
1000     return TCL_ERROR;
1001   }
1002
1003   devsym_crash_on_write(nWrite);
1004   return TCL_OK;
1005 }
1006
1007 /*
1008 ** tclcmd: unregister_devsim
1009 */
1010 static int SQLITE_TCLAPI dsUnregisterObjCmd(
1011   void * clientData,
1012   Tcl_Interp *interp,
1013   int objc,
1014   Tcl_Obj *CONST objv[]
1015 ){
1016   void devsym_unregister(void);
1017
1018   if( objc!=1 ){
1019     Tcl_WrongNumArgs(interp, 1, objv, "");
1020     return TCL_ERROR;
1021   }
1022
1023   devsym_unregister();
1024   return TCL_OK;
1025 }
1026
1027 /*
1028 ** tclcmd: register_jt_vfs ?-default? PARENT-VFS
1029 */
1030 static int SQLITE_TCLAPI jtObjCmd(
1031   void * clientData,
1032   Tcl_Interp *interp,
1033   int objc,
1034   Tcl_Obj *CONST objv[]
1035 ){
1036   int jt_register(char *, int);
1037   char *zParent = 0;
1038
1039   if( objc!=2 && objc!=3 ){
1040     Tcl_WrongNumArgs(interp, 1, objv, "?-default? PARENT-VFS");
1041     return TCL_ERROR;
1042   }
1043   zParent = Tcl_GetString(objv[1]);
1044   if( objc==3 ){
1045     if( strcmp(zParent, "-default") ){
1046       Tcl_AppendResult(interp,
1047           "bad option \"", zParent, "\": must be -default", 0
1048       );
1049       return TCL_ERROR;
1050     }
1051     zParent = Tcl_GetString(objv[2]);
1052   }
1053
1054   if( !(*zParent) ){
1055     zParent = 0;
1056   }
1057   if( jt_register(zParent, objc==3) ){
1058     Tcl_AppendResult(interp, "Error in jt_register", 0);
1059     return TCL_ERROR;
1060   }
1061
1062   return TCL_OK;
1063 }
1064
1065 /*
1066 ** tclcmd: unregister_jt_vfs
1067 */
1068 static int SQLITE_TCLAPI jtUnregisterObjCmd(
1069   void * clientData,
1070   Tcl_Interp *interp,
1071   int objc,
1072   Tcl_Obj *CONST objv[]
1073 ){
1074   void jt_unregister(void);
1075
1076   if( objc!=1 ){
1077     Tcl_WrongNumArgs(interp, 1, objv, "");
1078     return TCL_ERROR;
1079   }
1080
1081   jt_unregister();
1082   return TCL_OK;
1083 }
1084
1085 #endif /* SQLITE_OMIT_DISKIO */
1086
1087 /*
1088 ** This procedure registers the TCL procedures defined in this file.
1089 */
1090 int Sqlitetest6_Init(Tcl_Interp *interp){
1091 #ifndef SQLITE_OMIT_DISKIO
1092   Tcl_CreateObjCommand(interp, "sqlite3_crash_enable", crashEnableCmd, 0, 0);
1093   Tcl_CreateObjCommand(interp, "sqlite3_crashparams", crashParamsObjCmd, 0, 0);
1094   Tcl_CreateObjCommand(interp, "sqlite3_crash_now", crashNowCmd, 0, 0);
1095   Tcl_CreateObjCommand(interp, "sqlite3_simulate_device", devSymObjCmd, 0, 0);
1096   Tcl_CreateObjCommand(interp, "sqlite3_crash_on_write", writeCrashObjCmd,0,0);
1097   Tcl_CreateObjCommand(interp, "unregister_devsim", dsUnregisterObjCmd, 0, 0);
1098   Tcl_CreateObjCommand(interp, "register_jt_vfs", jtObjCmd, 0, 0);
1099   Tcl_CreateObjCommand(interp, "unregister_jt_vfs", jtUnregisterObjCmd, 0, 0);
1100 #endif
1101   return TCL_OK;
1102 }
1103
1104 #endif /* SQLITE_TEST */