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 #if defined(INCLUDE_SQLITE_TCL_H)
  20 #  include "sqlite_tcl.h"
  21 #else
  22 #  include "tcl.h"
  23 #endif
  24
  25 #ifndef SQLITE_OMIT_DISKIO  /* This file is a no-op if disk I/O is disabled */
  26
  27 /* #define TRACE_CRASHTEST */
  28
  29 typedef struct CrashFile CrashFile;
  30 typedef struct CrashGlobal CrashGlobal;
  31 typedef struct WriteBuffer WriteBuffer;
  32
  33 /*
  34 ** Method:
  35 **
  36 **   This layer is implemented as a wrapper around the "real"
  37 **   sqlite3_file object for the host system. Each time data is
  38 **   written to the file object, instead of being written to the
  39 **   underlying file, the write operation is stored in an in-memory
  40 **   structure (type WriteBuffer). This structure is placed at the
  41 **   end of a global ordered list (the write-list).
  42 **
  43 **   When data is read from a file object, the requested region is
  44 **   first retrieved from the real file. The write-list is then
  45 **   traversed and data copied from any overlapping WriteBuffer
  46 **   structures to the output buffer. i.e. a read() operation following
  47 **   one or more write() operations works as expected, even if no
  48 **   data has actually been written out to the real file.
  49 **
  50 **   When a fsync() operation is performed, an operating system crash
  51 **   may be simulated, in which case exit(-1) is called (the call to
  52 **   xSync() never returns). Whether or not a crash is simulated,
  53 **   the data associated with a subset of the WriteBuffer structures
  54 **   stored in the write-list is written to the real underlying files
  55 **   and the entries removed from the write-list. If a crash is simulated,
  56 **   a subset of the buffers may be corrupted before the data is written.
  57 **
  58 **   The exact subset of the write-list written and/or corrupted is
  59 **   determined by the simulated device characteristics and sector-size.
  60 **
  61 ** "Normal" mode:
  62 **
  63 **   Normal mode is used when the simulated device has none of the
  64 **   SQLITE_IOCAP_XXX flags set.
  65 **
  66 **   In normal mode, if the fsync() is not a simulated crash, the
  67 **   write-list is traversed from beginning to end. Each WriteBuffer
  68 **   structure associated with the file handle used to call xSync()
  69 **   is written to the real file and removed from the write-list.
  70 **
  71 **   If a crash is simulated, one of the following takes place for
  72 **   each WriteBuffer in the write-list, regardless of which
  73 **   file-handle it is associated with:
  74 **
  75 **     1. The buffer is correctly written to the file, just as if
  76 **        a crash were not being simulated.
  77 **
  78 **     2. Nothing is done.
  79 **
  80 **     3. Garbage data is written to all sectors of the file that
  81 **        overlap the region specified by the WriteBuffer. Or garbage
  82 **        data is written to some contiguous section within the
  83 **        overlapped sectors.
  84 **
  85 ** Device Characteristic flag handling:
  86 **
  87 **   If the IOCAP_ATOMIC flag is set, then option (3) above is
  88 **   never selected.
  89 **
  90 **   If the IOCAP_ATOMIC512 flag is set, and the WriteBuffer represents
  91 **   an aligned write() of an integer number of 512 byte regions, then
  92 **   option (3) above is never selected. Instead, each 512 byte region
  93 **   is either correctly written or left completely untouched. Similar
  94 **   logic governs the behavior if any of the other ATOMICXXX flags
  95 **   is set.
  96 **
  97 **   If either the IOCAP_SAFEAPPEND or IOCAP_SEQUENTIAL flags are set
  98 **   and a crash is being simulated, then an entry of the write-list is
  99 **   selected at random. Everything in the list after the selected entry
 100 **   is discarded before processing begins.
 101 **
 102 **   If IOCAP_SEQUENTIAL is set and a crash is being simulated, option
 103 **   (1) is selected for all write-list entries except the last. If a
 104 **   crash is not being simulated, then all entries in the write-list
 105 **   that occur before at least one write() on the file-handle specified
 106 **   as part of the xSync() are written to their associated real files.
 107 **
 108 **   If IOCAP_SAFEAPPEND is set and the first byte written by the write()
 109 **   operation is one byte past the current end of the file, then option
 110 **   (1) is always selected.
 111 */
 112
 113 /*
 114 ** Each write operation in the write-list is represented by an instance
 115 ** of the following structure.
 116 **
 117 ** If zBuf is 0, then this structure represents a call to xTruncate(),
 118 ** not xWrite(). In that case, iOffset is the size that the file is
 119 ** truncated to.
 120 */
 121 struct WriteBuffer {
 122   i64 iOffset;                 /* Byte offset of the start of this write() */
 123   int nBuf;                    /* Number of bytes written */
 124   u8 *zBuf;                    /* Pointer to copy of written data */
 125   CrashFile *pFile;            /* File this write() applies to */
 126
 127   WriteBuffer *pNext;          /* Next in CrashGlobal.pWriteList */
 128 };
 129
 130 struct CrashFile {
 131   const sqlite3_io_methods *pMethod;   /* Must be first */
 132   sqlite3_file *pRealFile;             /* Underlying "real" file handle */
 133   char *zName;
 134   int flags;                           /* Flags the file was opened with */
 135
 136   /* Cache of the entire file. This is used to speed up OsRead() and
 137   ** OsFileSize() calls. Although both could be done by traversing the
 138   ** write-list, in practice this is impractically slow.
 139   */
 140   u8 *zData;                           /* Buffer containing file contents */
 141   int nData;                           /* Size of buffer allocated at zData */
 142   i64 iSize;                           /* Size of file in bytes */
 143 };
 144
 145 struct CrashGlobal {
 146   WriteBuffer *pWriteList;     /* Head of write-list */
 147   WriteBuffer *pWriteListEnd;  /* End of write-list */
 148
 149   int iSectorSize;             /* Value of simulated sector size */
 150   int iDeviceCharacteristics;  /* Value of simulated device characteristics */
 151
 152   int iCrash;                  /* Crash on the iCrash'th call to xSync() */
 153   char zCrashFile[500];        /* Crash during an xSync() on this file */
 154 };
 155
 156 static CrashGlobal g = {0, 0, SQLITE_DEFAULT_SECTOR_SIZE, 0, 0};
 157
 158 /*
 159 ** Set this global variable to 1 to enable crash testing.
 160 */
 161 static int sqlite3CrashTestEnable = 0;
 162
 163 static void *crash_malloc(int nByte){
 164   return (void *)Tcl_AttemptAlloc((size_t)nByte);
 165 }
 166 static void crash_free(void *p){
 167   Tcl_Free(p);
 168 }
 169 static void *crash_realloc(void *p, int n){
 170   return (void *)Tcl_AttemptRealloc(p, (size_t)n);
 171 }
 172
 173 /*
 174 ** Wrapper around the sqlite3OsWrite() function that avoids writing to the
 175 ** 512 byte block begining at offset PENDING_BYTE.
 176 */
 177 static int writeDbFile(CrashFile *p, u8 *z, i64 iAmt, i64 iOff){
 178   int rc = SQLITE_OK;
 179   int iSkip = 0;
 180   if( (iAmt-iSkip)>0 ){
 181     rc = sqlite3OsWrite(p->pRealFile, &z[iSkip], (int)(iAmt-iSkip), iOff+iSkip);
 182   }
 183   return rc;
 184 }
 185
 186 /*
 187 ** Flush the write-list as if xSync() had been called on file handle
 188 ** pFile. If isCrash is true, simulate a crash.
 189 */
 190 static int writeListSync(CrashFile *pFile, int isCrash){
 191   int rc = SQLITE_OK;
 192   int iDc = g.iDeviceCharacteristics;
 193
 194   WriteBuffer *pWrite;
 195   WriteBuffer **ppPtr;
 196
 197   /* If this is not a crash simulation, set pFinal to point to the
 198   ** last element of the write-list that is associated with file handle
 199   ** pFile.
 200   **
 201   ** If this is a crash simulation, set pFinal to an arbitrarily selected
 202   ** element of the write-list.
 203   */
 204   WriteBuffer *pFinal = 0;
 205   if( !isCrash ){
 206     for(pWrite=g.pWriteList; pWrite; pWrite=pWrite->pNext){
 207       if( pWrite->pFile==pFile ){
 208         pFinal = pWrite;
 209       }
 210     }
 211   }else if( iDc&(SQLITE_IOCAP_SEQUENTIAL|SQLITE_IOCAP_SAFE_APPEND) ){
 212     int nWrite = 0;
 213     int iFinal;
 214     for(pWrite=g.pWriteList; pWrite; pWrite=pWrite->pNext) nWrite++;
 215     sqlite3_randomness(sizeof(int), &iFinal);
 216     iFinal = ((iFinal<0)?-1*iFinal:iFinal)%nWrite;
 217     for(pWrite=g.pWriteList; iFinal>0; pWrite=pWrite->pNext) iFinal--;
 218     pFinal = pWrite;
 219   }
 220
 221 #ifdef TRACE_CRASHTEST
 222   if( pFile ){
 223     printf("Sync %s (is %s crash)\n", pFile->zName, (isCrash?"a":"not a"));
 224   }
 225 #endif
 226
 227   ppPtr = &g.pWriteList;
 228   for(pWrite=*ppPtr; rc==SQLITE_OK && pWrite; pWrite=*ppPtr){
 229     sqlite3_file *pRealFile = pWrite->pFile->pRealFile;
 230
 231     /* (eAction==1)      -> write block out normally,
 232     ** (eAction==2)      -> do nothing,
 233     ** (eAction==3)      -> trash sectors.
 234     */
 235     int eAction = 0;
 236     if( !isCrash ){
 237       eAction = 2;
 238       if( (pWrite->pFile==pFile || iDc&SQLITE_IOCAP_SEQUENTIAL) ){
 239         eAction = 1;
 240       }
 241     }else{
 242       char random;
 243       sqlite3_randomness(1, &random);
 244
 245       /* Do not select option 3 (sector trashing) if the IOCAP_ATOMIC flag
 246       ** is set or this is an OsTruncate(), not an Oswrite().
 247       */
 248       if( (iDc&SQLITE_IOCAP_ATOMIC) || (pWrite->zBuf==0) ){
 249         random &= 0x01;
 250       }
 251
 252       /* If IOCAP_SEQUENTIAL is set and this is not the final entry
 253       ** in the truncated write-list, always select option 1 (write
 254       ** out correctly).
 255       */
 256       if( (iDc&SQLITE_IOCAP_SEQUENTIAL && pWrite!=pFinal) ){
 257         random = 0;
 258       }
 259
 260       /* If IOCAP_SAFE_APPEND is set and this OsWrite() operation is
 261       ** an append (first byte of the written region is 1 byte past the
 262       ** current EOF), always select option 1 (write out correctly).
 263       */
 264       if( iDc&SQLITE_IOCAP_SAFE_APPEND && pWrite->zBuf ){
 265         i64 iSize;
 266         sqlite3OsFileSize(pRealFile, &iSize);
 267         if( iSize==pWrite->iOffset ){
 268           random = 0;
 269         }
 270       }
 271
 272       if( (random&0x06)==0x06 ){
 273         eAction = 3;
 274       }else{
 275         eAction = ((random&0x01)?2:1);
 276       }
 277     }
 278
 279     switch( eAction ){
 280       case 1: {               /* Write out correctly */
 281         if( pWrite->zBuf ){
 282           rc = writeDbFile(
 283               pWrite->pFile, pWrite->zBuf, pWrite->nBuf, pWrite->iOffset
 284           );
 285         }else{
 286           rc = sqlite3OsTruncate(pRealFile, pWrite->iOffset);
 287         }
 288         *ppPtr = pWrite->pNext;
 289 #ifdef TRACE_CRASHTEST
 290         if( isCrash ){
 291           printf("Writing %d bytes @ %d (%s)\n",
 292             pWrite->nBuf, (int)pWrite->iOffset, pWrite->pFile->zName
 293           );
 294         }
 295 #endif
 296         crash_free(pWrite);
 297         break;
 298       }
 299       case 2: {               /* Do nothing */
 300         ppPtr = &pWrite->pNext;
 301 #ifdef TRACE_CRASHTEST
 302         if( isCrash ){
 303           printf("Omiting %d bytes @ %d (%s)\n",
 304             pWrite->nBuf, (int)pWrite->iOffset, pWrite->pFile->zName
 305           );
 306         }
 307 #endif
 308         break;
 309       }
 310       case 3: {               /* Trash sectors */
 311         u8 *zGarbage;
 312         int iFirst = (int)(pWrite->iOffset/g.iSectorSize);
 313         int iLast = (int)((pWrite->iOffset+pWrite->nBuf-1)/g.iSectorSize);
 314
 315         assert(pWrite->zBuf);
 316
 317 #ifdef TRACE_CRASHTEST
 318         printf("Trashing %d sectors (%d bytes) @ %lld (sector %d) (%s)\n",
 319             1+iLast-iFirst, (1+iLast-iFirst)*g.iSectorSize,
 320             pWrite->iOffset, iFirst, pWrite->pFile->zName
 321         );
 322 #endif
 323
 324         zGarbage = crash_malloc(g.iSectorSize);
 325         if( zGarbage ){
 326           sqlite3_int64 i;
 327           for(i=iFirst; rc==SQLITE_OK && i<=iLast; i++){
 328             sqlite3_randomness(g.iSectorSize, zGarbage);
 329             rc = writeDbFile(
 330               pWrite->pFile, zGarbage, g.iSectorSize, i*g.iSectorSize
 331             );
 332           }
 333           crash_free(zGarbage);
 334         }else{
 335           rc = SQLITE_NOMEM;
 336         }
 337
 338         ppPtr = &pWrite->pNext;
 339         break;
 340       }
 341
 342       default:
 343         assert(!"Cannot happen");
 344     }
 345
 346     if( pWrite==pFinal ) break;
 347   }
 348
 349   if( rc==SQLITE_OK && isCrash ){
 350     exit(-1);
 351   }
 352
 353   for(pWrite=g.pWriteList; pWrite && pWrite->pNext; pWrite=pWrite->pNext);
 354   g.pWriteListEnd = pWrite;
 355
 356   return rc;
 357 }
 358
 359 /*
 360 ** Add an entry to the end of the write-list.
 361 */
 362 static int writeListAppend(
 363   sqlite3_file *pFile,
 364   sqlite3_int64 iOffset,
 365   const u8 *zBuf,
 366   int nBuf
 367 ){
 368   WriteBuffer *pNew;
 369
 370   assert((zBuf && nBuf) || (!nBuf && !zBuf));
 371
 372   pNew = (WriteBuffer *)crash_malloc(sizeof(WriteBuffer) + nBuf);
 373   if( pNew==0 ){
 374     fprintf(stderr, "out of memory in the crash simulator\n");
 375   }
 376   memset(pNew, 0, sizeof(WriteBuffer)+nBuf);
 377   pNew->iOffset = iOffset;
 378   pNew->nBuf = nBuf;
 379   pNew->pFile = (CrashFile *)pFile;
 380   if( zBuf ){
 381     pNew->zBuf = (u8 *)&pNew[1];
 382     memcpy(pNew->zBuf, zBuf, nBuf);
 383   }
 384
 385   if( g.pWriteList ){
 386     assert(g.pWriteListEnd);
 387     g.pWriteListEnd->pNext = pNew;
 388   }else{
 389     g.pWriteList = pNew;
 390   }
 391   g.pWriteListEnd = pNew;
 392
 393   return SQLITE_OK;
 394 }
 395
 396 /*
 397 ** Close a crash-file.
 398 */
 399 static int cfClose(sqlite3_file *pFile){
 400   CrashFile *pCrash = (CrashFile *)pFile;
 401   writeListSync(pCrash, 0);
 402   sqlite3OsClose(pCrash->pRealFile);
 403   return SQLITE_OK;
 404 }
 405
 406 /*
 407 ** Read data from a crash-file.
 408 */
 409 static int cfRead(
 410   sqlite3_file *pFile,
 411   void *zBuf,
 412   int iAmt,
 413   sqlite_int64 iOfst
 414 ){
 415   CrashFile *pCrash = (CrashFile *)pFile;
 416   int nCopy = (int)MIN((i64)iAmt, (pCrash->iSize - iOfst));
 417
 418   if( nCopy>0 ){
 419     memcpy(zBuf, &pCrash->zData[iOfst], nCopy);
 420   }
 421
 422   /* Check the file-size to see if this is a short-read */
 423   if( nCopy<iAmt ){
 424     return SQLITE_IOERR_SHORT_READ;
 425   }
 426
 427   return SQLITE_OK;
 428 }
 429
 430 /*
 431 ** Write data to a crash-file.
 432 */
 433 static int cfWrite(
 434   sqlite3_file *pFile,
 435   const void *zBuf,
 436   int iAmt,
 437   sqlite_int64 iOfst
 438 ){
 439   CrashFile *pCrash = (CrashFile *)pFile;
 440   if( iAmt+iOfst>pCrash->iSize ){
 441     pCrash->iSize = (int)(iAmt+iOfst);
 442   }
 443   while( pCrash->iSize>pCrash->nData ){
 444     u8 *zNew;
 445     int nNew = (pCrash->nData*2) + 4096;
 446     zNew = crash_realloc(pCrash->zData, nNew);
 447     if( !zNew ){
 448       return SQLITE_NOMEM;
 449     }
 450     memset(&zNew[pCrash->nData], 0, nNew-pCrash->nData);
 451     pCrash->nData = nNew;
 452     pCrash->zData = zNew;
 453   }
 454   memcpy(&pCrash->zData[iOfst], zBuf, iAmt);
 455   return writeListAppend(pFile, iOfst, zBuf, iAmt);
 456 }
 457
 458 /*
 459 ** Truncate a crash-file.
 460 */
 461 static int cfTruncate(sqlite3_file *pFile, sqlite_int64 size){
 462   CrashFile *pCrash = (CrashFile *)pFile;
 463   assert(size>=0);
 464   if( pCrash->iSize>size ){
 465     pCrash->iSize = (int)size;
 466   }
 467   return writeListAppend(pFile, size, 0, 0);
 468 }
 469
 470 /*
 471 ** Sync a crash-file.
 472 */
 473 static int cfSync(sqlite3_file *pFile, int flags){
 474   CrashFile *pCrash = (CrashFile *)pFile;
 475   int isCrash = 0;
 476
 477   const char *zName = pCrash->zName;
 478   const char *zCrashFile = g.zCrashFile;
 479   int nName = (int)strlen(zName);
 480   int nCrashFile = (int)strlen(zCrashFile);
 481
 482   if( nCrashFile>0 && zCrashFile[nCrashFile-1]=='*' ){
 483     nCrashFile--;
 484     if( nName>nCrashFile ) nName = nCrashFile;
 485   }
 486
 487 #ifdef TRACE_CRASHTEST
 488   printf("cfSync(): nName = %d, nCrashFile = %d, zName = %s, zCrashFile = %s\n",
 489          nName, nCrashFile, zName, zCrashFile);
 490 #endif
 491
 492   if( nName==nCrashFile && 0==memcmp(zName, zCrashFile, nName) ){
 493 #ifdef TRACE_CRASHTEST
 494     printf("cfSync(): name matched, g.iCrash = %d\n", g.iCrash);
 495 #endif
 496     if( (--g.iCrash)==0 ) isCrash = 1;
 497   }
 498
 499   return writeListSync(pCrash, isCrash);
 500 }
 501
 502 /*
 503 ** Return the current file-size of the crash-file.
 504 */
 505 static int cfFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){
 506   CrashFile *pCrash = (CrashFile *)pFile;
 507   *pSize = (i64)pCrash->iSize;
 508   return SQLITE_OK;
 509 }
 510
 511 /*
 512 ** Calls related to file-locks are passed on to the real file handle.
 513 */
 514 static int cfLock(sqlite3_file *pFile, int eLock){
 515   return sqlite3OsLock(((CrashFile *)pFile)->pRealFile, eLock);
 516 }
 517 static int cfUnlock(sqlite3_file *pFile, int eLock){
 518   return sqlite3OsUnlock(((CrashFile *)pFile)->pRealFile, eLock);
 519 }
 520 static int cfCheckReservedLock(sqlite3_file *pFile, int *pResOut){
 521   return sqlite3OsCheckReservedLock(((CrashFile *)pFile)->pRealFile, pResOut);
 522 }
 523 static int cfFileControl(sqlite3_file *pFile, int op, void *pArg){
 524   if( op==SQLITE_FCNTL_SIZE_HINT ){
 525     CrashFile *pCrash = (CrashFile *)pFile;
 526     i64 nByte = *(i64 *)pArg;
 527     if( nByte>pCrash->iSize ){
 528       if( SQLITE_OK==writeListAppend(pFile, nByte, 0, 0) ){
 529         pCrash->iSize = (int)nByte;
 530       }
 531     }
 532     return SQLITE_OK;
 533   }
 534   return sqlite3OsFileControl(((CrashFile *)pFile)->pRealFile, op, pArg);
 535 }
 536
 537 /*
 538 ** The xSectorSize() and xDeviceCharacteristics() functions return
 539 ** the global values configured by the [sqlite_crashparams] tcl
 540 *  interface.
 541 */
 542 static int cfSectorSize(sqlite3_file *pFile){
 543   return g.iSectorSize;
 544 }
 545 static int cfDeviceCharacteristics(sqlite3_file *pFile){
 546   return g.iDeviceCharacteristics;
 547 }
 548
 549 /*
 550 ** Pass-throughs for WAL support.
 551 */
 552 static int cfShmLock(sqlite3_file *pFile, int ofst, int n, int flags){
 553   return sqlite3OsShmLock(((CrashFile*)pFile)->pRealFile, ofst, n, flags);
 554 }
 555 static void cfShmBarrier(sqlite3_file *pFile){
 556   sqlite3OsShmBarrier(((CrashFile*)pFile)->pRealFile);
 557 }
 558 static int cfShmUnmap(sqlite3_file *pFile, int delFlag){
 559   return sqlite3OsShmUnmap(((CrashFile*)pFile)->pRealFile, delFlag);
 560 }
 561 static int cfShmMap(
 562   sqlite3_file *pFile,            /* Handle open on database file */
 563   int iRegion,                    /* Region to retrieve */
 564   int sz,                         /* Size of regions */
 565   int w,                          /* True to extend file if necessary */
 566   void volatile **pp              /* OUT: Mapped memory */
 567 ){
 568   return sqlite3OsShmMap(((CrashFile*)pFile)->pRealFile, 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     int 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       int nObj;
 776       if( Tcl_ListObjGetElements(interp, objv[i+1], &nObj, &apObj) ){
 777         return TCL_ERROR;
 778       }
 779       for(j=0; j<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   int nCrashFile, iDc, iSectorSize;
 925
 926   iDc = -1;
 927   iSectorSize = -1;
 928
 929   if( objc<3 ){
 930     Tcl_WrongNumArgs(interp, 1, objv, "?OPTIONS? DELAY CRASHFILE");
 931     goto error;
 932   }
 933
 934   zCrashFile = Tcl_GetStringFromObj(objv[objc-1], &nCrashFile);
 935   if( nCrashFile>=sizeof(g.zCrashFile) ){
 936     Tcl_AppendResult(interp, "Filename is too long: \"", zCrashFile, "\"", 0);
 937     goto error;
 938   }
 939   if( Tcl_GetIntFromObj(interp, objv[objc-2], &iDelay) ){
 940     goto error;
 941   }
 942
 943   if( processDevSymArgs(interp, objc-3, &objv[1], &iDc, &iSectorSize) ){
 944     return TCL_ERROR;
 945   }
 946
 947   if( iDc>=0 ){
 948     g.iDeviceCharacteristics = iDc;
 949   }
 950   if( iSectorSize>=0 ){
 951     g.iSectorSize = iSectorSize;
 952   }
 953
 954   g.iCrash = iDelay;
 955   memcpy(g.zCrashFile, zCrashFile, nCrashFile+1);
 956   sqlite3CrashTestEnable = 1;
 957   return TCL_OK;
 958
 959 error:
 960   return TCL_ERROR;
 961 }
 962
 963 static int SQLITE_TCLAPI devSymObjCmd(
 964   void * clientData,
 965   Tcl_Interp *interp,
 966   int objc,
 967   Tcl_Obj *CONST objv[]
 968 ){
 969   void devsym_register(int iDeviceChar, int iSectorSize);
 970
 971   int iDc = -1;
 972   int iSectorSize = -1;
 973
 974   if( processDevSymArgs(interp, objc-1, &objv[1], &iDc, &iSectorSize) ){
 975     return TCL_ERROR;
 976   }
 977   devsym_register(iDc, iSectorSize);
 978
 979   return TCL_OK;
 980 }
 981
 982 /*
 983 ** tclcmd: sqlite3_crash_on_write N
 984 */
 985 static int SQLITE_TCLAPI writeCrashObjCmd(
 986   void * clientData,
 987   Tcl_Interp *interp,
 988   int objc,
 989   Tcl_Obj *CONST objv[]
 990 ){
 991   void devsym_crash_on_write(int);
 992   int nWrite = 0;
 993
 994   if( objc!=2 ){
 995     Tcl_WrongNumArgs(interp, 1, objv, "NWRITE");
 996     return TCL_ERROR;
 997   }
 998   if( Tcl_GetIntFromObj(interp, objv[1], &nWrite) ){
 999     return TCL_ERROR;
1000   }
1001
1002   devsym_crash_on_write(nWrite);
1003   return TCL_OK;
1004 }
1005
1006 /*
1007 ** tclcmd: unregister_devsim
1008 */
1009 static int SQLITE_TCLAPI dsUnregisterObjCmd(
1010   void * clientData,
1011   Tcl_Interp *interp,
1012   int objc,
1013   Tcl_Obj *CONST objv[]
1014 ){
1015   void devsym_unregister(void);
1016
1017   if( objc!=1 ){
1018     Tcl_WrongNumArgs(interp, 1, objv, "");
1019     return TCL_ERROR;
1020   }
1021
1022   devsym_unregister();
1023   return TCL_OK;
1024 }
1025
1026 /*
1027 ** tclcmd: register_jt_vfs ?-default? PARENT-VFS
1028 */
1029 static int SQLITE_TCLAPI jtObjCmd(
1030   void * clientData,
1031   Tcl_Interp *interp,
1032   int objc,
1033   Tcl_Obj *CONST objv[]
1034 ){
1035   int jt_register(char *, int);
1036   char *zParent = 0;
1037
1038   if( objc!=2 && objc!=3 ){
1039     Tcl_WrongNumArgs(interp, 1, objv, "?-default? PARENT-VFS");
1040     return TCL_ERROR;
1041   }
1042   zParent = Tcl_GetString(objv[1]);
1043   if( objc==3 ){
1044     if( strcmp(zParent, "-default") ){
1045       Tcl_AppendResult(interp,
1046           "bad option \"", zParent, "\": must be -default", 0
1047       );
1048       return TCL_ERROR;
1049     }
1050     zParent = Tcl_GetString(objv[2]);
1051   }
1052
1053   if( !(*zParent) ){
1054     zParent = 0;
1055   }
1056   if( jt_register(zParent, objc==3) ){
1057     Tcl_AppendResult(interp, "Error in jt_register", 0);
1058     return TCL_ERROR;
1059   }
1060
1061   return TCL_OK;
1062 }
1063
1064 /*
1065 ** tclcmd: unregister_jt_vfs
1066 */
1067 static int SQLITE_TCLAPI jtUnregisterObjCmd(
1068   void * clientData,
1069   Tcl_Interp *interp,
1070   int objc,
1071   Tcl_Obj *CONST objv[]
1072 ){
1073   void jt_unregister(void);
1074
1075   if( objc!=1 ){
1076     Tcl_WrongNumArgs(interp, 1, objv, "");
1077     return TCL_ERROR;
1078   }
1079
1080   jt_unregister();
1081   return TCL_OK;
1082 }
1083
1084 #endif /* SQLITE_OMIT_DISKIO */
1085
1086 /*
1087 ** This procedure registers the TCL procedures defined in this file.
1088 */
1089 int Sqlitetest6_Init(Tcl_Interp *interp){
1090 #ifndef SQLITE_OMIT_DISKIO
1091   Tcl_CreateObjCommand(interp, "sqlite3_crash_enable", crashEnableCmd, 0, 0);
1092   Tcl_CreateObjCommand(interp, "sqlite3_crashparams", crashParamsObjCmd, 0, 0);
1093   Tcl_CreateObjCommand(interp, "sqlite3_crash_now", crashNowCmd, 0, 0);
1094   Tcl_CreateObjCommand(interp, "sqlite3_simulate_device", devSymObjCmd, 0, 0);
1095   Tcl_CreateObjCommand(interp, "sqlite3_crash_on_write", writeCrashObjCmd,0,0);
1096   Tcl_CreateObjCommand(interp, "unregister_devsim", dsUnregisterObjCmd, 0, 0);
1097   Tcl_CreateObjCommand(interp, "register_jt_vfs", jtObjCmd, 0, 0);
1098   Tcl_CreateObjCommand(interp, "unregister_jt_vfs", jtUnregisterObjCmd, 0, 0);
1099 #endif
1100   return TCL_OK;
1101 }
1102
1103 #endif /* SQLITE_TEST */