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_Alloc((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_Realloc(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 @ %lld (sector %d) (%s)\n",
 319             1+iLast-iFirst, pWrite->iOffset, iFirst, pWrite->pFile->zName
 320         );
 321 #endif
 322
 323         zGarbage = crash_malloc(g.iSectorSize);
 324         if( zGarbage ){
 325           sqlite3_int64 i;
 326           for(i=iFirst; rc==SQLITE_OK && i<=iLast; i++){
 327             sqlite3_randomness(g.iSectorSize, zGarbage);
 328             rc = writeDbFile(
 329               pWrite->pFile, zGarbage, g.iSectorSize, i*g.iSectorSize
 330             );
 331           }
 332           crash_free(zGarbage);
 333         }else{
 334           rc = SQLITE_NOMEM;
 335         }
 336
 337         ppPtr = &pWrite->pNext;
 338         break;
 339       }
 340
 341       default:
 342         assert(!"Cannot happen");
 343     }
 344
 345     if( pWrite==pFinal ) break;
 346   }
 347
 348   if( rc==SQLITE_OK && isCrash ){
 349     exit(-1);
 350   }
 351
 352   for(pWrite=g.pWriteList; pWrite && pWrite->pNext; pWrite=pWrite->pNext);
 353   g.pWriteListEnd = pWrite;
 354
 355   return rc;
 356 }
 357
 358 /*
 359 ** Add an entry to the end of the write-list.
 360 */
 361 static int writeListAppend(
 362   sqlite3_file *pFile,
 363   sqlite3_int64 iOffset,
 364   const u8 *zBuf,
 365   int nBuf
 366 ){
 367   WriteBuffer *pNew;
 368
 369   assert((zBuf && nBuf) || (!nBuf && !zBuf));
 370
 371   pNew = (WriteBuffer *)crash_malloc(sizeof(WriteBuffer) + nBuf);
 372   if( pNew==0 ){
 373     fprintf(stderr, "out of memory in the crash simulator\n");
 374   }
 375   memset(pNew, 0, sizeof(WriteBuffer)+nBuf);
 376   pNew->iOffset = iOffset;
 377   pNew->nBuf = nBuf;
 378   pNew->pFile = (CrashFile *)pFile;
 379   if( zBuf ){
 380     pNew->zBuf = (u8 *)&pNew[1];
 381     memcpy(pNew->zBuf, zBuf, nBuf);
 382   }
 383
 384   if( g.pWriteList ){
 385     assert(g.pWriteListEnd);
 386     g.pWriteListEnd->pNext = pNew;
 387   }else{
 388     g.pWriteList = pNew;
 389   }
 390   g.pWriteListEnd = pNew;
 391
 392   return SQLITE_OK;
 393 }
 394
 395 /*
 396 ** Close a crash-file.
 397 */
 398 static int cfClose(sqlite3_file *pFile){
 399   CrashFile *pCrash = (CrashFile *)pFile;
 400   writeListSync(pCrash, 0);
 401   sqlite3OsClose(pCrash->pRealFile);
 402   return SQLITE_OK;
 403 }
 404
 405 /*
 406 ** Read data from a crash-file.
 407 */
 408 static int cfRead(
 409   sqlite3_file *pFile,
 410   void *zBuf,
 411   int iAmt,
 412   sqlite_int64 iOfst
 413 ){
 414   CrashFile *pCrash = (CrashFile *)pFile;
 415   int nCopy = (int)MIN((i64)iAmt, (pCrash->iSize - iOfst));
 416
 417   if( nCopy>0 ){
 418     memcpy(zBuf, &pCrash->zData[iOfst], nCopy);
 419   }
 420
 421   /* Check the file-size to see if this is a short-read */
 422   if( nCopy<iAmt ){
 423     return SQLITE_IOERR_SHORT_READ;
 424   }
 425
 426   return SQLITE_OK;
 427 }
 428
 429 /*
 430 ** Write data to a crash-file.
 431 */
 432 static int cfWrite(
 433   sqlite3_file *pFile,
 434   const void *zBuf,
 435   int iAmt,
 436   sqlite_int64 iOfst
 437 ){
 438   CrashFile *pCrash = (CrashFile *)pFile;
 439   if( iAmt+iOfst>pCrash->iSize ){
 440     pCrash->iSize = (int)(iAmt+iOfst);
 441   }
 442   while( pCrash->iSize>pCrash->nData ){
 443     u8 *zNew;
 444     int nNew = (pCrash->nData*2) + 4096;
 445     zNew = crash_realloc(pCrash->zData, nNew);
 446     if( !zNew ){
 447       return SQLITE_NOMEM;
 448     }
 449     memset(&zNew[pCrash->nData], 0, nNew-pCrash->nData);
 450     pCrash->nData = nNew;
 451     pCrash->zData = zNew;
 452   }
 453   memcpy(&pCrash->zData[iOfst], zBuf, iAmt);
 454   return writeListAppend(pFile, iOfst, zBuf, iAmt);
 455 }
 456
 457 /*
 458 ** Truncate a crash-file.
 459 */
 460 static int cfTruncate(sqlite3_file *pFile, sqlite_int64 size){
 461   CrashFile *pCrash = (CrashFile *)pFile;
 462   assert(size>=0);
 463   if( pCrash->iSize>size ){
 464     pCrash->iSize = (int)size;
 465   }
 466   return writeListAppend(pFile, size, 0, 0);
 467 }
 468
 469 /*
 470 ** Sync a crash-file.
 471 */
 472 static int cfSync(sqlite3_file *pFile, int flags){
 473   CrashFile *pCrash = (CrashFile *)pFile;
 474   int isCrash = 0;
 475
 476   const char *zName = pCrash->zName;
 477   const char *zCrashFile = g.zCrashFile;
 478   int nName = (int)strlen(zName);
 479   int nCrashFile = (int)strlen(zCrashFile);
 480
 481   if( nCrashFile>0 && zCrashFile[nCrashFile-1]=='*' ){
 482     nCrashFile--;
 483     if( nName>nCrashFile ) nName = nCrashFile;
 484   }
 485
 486 #ifdef TRACE_CRASHTEST
 487   printf("cfSync(): nName = %d, nCrashFile = %d, zName = %s, zCrashFile = %s\n",
 488          nName, nCrashFile, zName, zCrashFile);
 489 #endif
 490
 491   if( nName==nCrashFile && 0==memcmp(zName, zCrashFile, nName) ){
 492 #ifdef TRACE_CRASHTEST
 493     printf("cfSync(): name matched, g.iCrash = %d\n", g.iCrash);
 494 #endif
 495     if( (--g.iCrash)==0 ) isCrash = 1;
 496   }
 497
 498   return writeListSync(pCrash, isCrash);
 499 }
 500
 501 /*
 502 ** Return the current file-size of the crash-file.
 503 */
 504 static int cfFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){
 505   CrashFile *pCrash = (CrashFile *)pFile;
 506   *pSize = (i64)pCrash->iSize;
 507   return SQLITE_OK;
 508 }
 509
 510 /*
 511 ** Calls related to file-locks are passed on to the real file handle.
 512 */
 513 static int cfLock(sqlite3_file *pFile, int eLock){
 514   return sqlite3OsLock(((CrashFile *)pFile)->pRealFile, eLock);
 515 }
 516 static int cfUnlock(sqlite3_file *pFile, int eLock){
 517   return sqlite3OsUnlock(((CrashFile *)pFile)->pRealFile, eLock);
 518 }
 519 static int cfCheckReservedLock(sqlite3_file *pFile, int *pResOut){
 520   return sqlite3OsCheckReservedLock(((CrashFile *)pFile)->pRealFile, pResOut);
 521 }
 522 static int cfFileControl(sqlite3_file *pFile, int op, void *pArg){
 523   if( op==SQLITE_FCNTL_SIZE_HINT ){
 524     CrashFile *pCrash = (CrashFile *)pFile;
 525     i64 nByte = *(i64 *)pArg;
 526     if( nByte>pCrash->iSize ){
 527       if( SQLITE_OK==writeListAppend(pFile, nByte, 0, 0) ){
 528         pCrash->iSize = (int)nByte;
 529       }
 530     }
 531     return SQLITE_OK;
 532   }
 533   return sqlite3OsFileControl(((CrashFile *)pFile)->pRealFile, op, pArg);
 534 }
 535
 536 /*
 537 ** The xSectorSize() and xDeviceCharacteristics() functions return
 538 ** the global values configured by the [sqlite_crashparams] tcl
 539 *  interface.
 540 */
 541 static int cfSectorSize(sqlite3_file *pFile){
 542   return g.iSectorSize;
 543 }
 544 static int cfDeviceCharacteristics(sqlite3_file *pFile){
 545   return g.iDeviceCharacteristics;
 546 }
 547
 548 /*
 549 ** Pass-throughs for WAL support.
 550 */
 551 static int cfShmLock(sqlite3_file *pFile, int ofst, int n, int flags){
 552   return sqlite3OsShmLock(((CrashFile*)pFile)->pRealFile, ofst, n, flags);
 553 }
 554 static void cfShmBarrier(sqlite3_file *pFile){
 555   sqlite3OsShmBarrier(((CrashFile*)pFile)->pRealFile);
 556 }
 557 static int cfShmUnmap(sqlite3_file *pFile, int delFlag){
 558   return sqlite3OsShmUnmap(((CrashFile*)pFile)->pRealFile, 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   return sqlite3OsShmMap(((CrashFile*)pFile)->pRealFile, iRegion, sz, w, pp);
 568 }
 569
 570 static const sqlite3_io_methods CrashFileVtab = {
 571   2,                            /* iVersion */
 572   cfClose,                      /* xClose */
 573   cfRead,                       /* xRead */
 574   cfWrite,                      /* xWrite */
 575   cfTruncate,                   /* xTruncate */
 576   cfSync,                       /* xSync */
 577   cfFileSize,                   /* xFileSize */
 578   cfLock,                       /* xLock */
 579   cfUnlock,                     /* xUnlock */
 580   cfCheckReservedLock,          /* xCheckReservedLock */
 581   cfFileControl,                /* xFileControl */
 582   cfSectorSize,                 /* xSectorSize */
 583   cfDeviceCharacteristics,      /* xDeviceCharacteristics */
 584   cfShmMap,                     /* xShmMap */
 585   cfShmLock,                    /* xShmLock */
 586   cfShmBarrier,                 /* xShmBarrier */
 587   cfShmUnmap                    /* xShmUnmap */
 588 };
 589
 590 /*
 591 ** Application data for the crash VFS
 592 */
 593 struct crashAppData {
 594   sqlite3_vfs *pOrig;                   /* Wrapped vfs structure */
 595 };
 596
 597 /*
 598 ** Open a crash-file file handle.
 599 **
 600 ** The caller will have allocated pVfs->szOsFile bytes of space
 601 ** at pFile. This file uses this space for the CrashFile structure
 602 ** and allocates space for the "real" file structure using
 603 ** sqlite3_malloc(). The assumption here is (pVfs->szOsFile) is
 604 ** equal or greater than sizeof(CrashFile).
 605 */
 606 static int cfOpen(
 607   sqlite3_vfs *pCfVfs,
 608   const char *zName,
 609   sqlite3_file *pFile,
 610   int flags,
 611   int *pOutFlags
 612 ){
 613   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 614   int rc;
 615   CrashFile *pWrapper = (CrashFile *)pFile;
 616   sqlite3_file *pReal = (sqlite3_file*)&pWrapper[1];
 617
 618   memset(pWrapper, 0, sizeof(CrashFile));
 619   rc = sqlite3OsOpen(pVfs, zName, pReal, flags, pOutFlags);
 620
 621   if( rc==SQLITE_OK ){
 622     i64 iSize;
 623     pWrapper->pMethod = &CrashFileVtab;
 624     pWrapper->zName = (char *)zName;
 625     pWrapper->pRealFile = pReal;
 626     rc = sqlite3OsFileSize(pReal, &iSize);
 627     pWrapper->iSize = (int)iSize;
 628     pWrapper->flags = flags;
 629   }
 630   if( rc==SQLITE_OK ){
 631     pWrapper->nData = (int)(4096 + pWrapper->iSize);
 632     pWrapper->zData = crash_malloc(pWrapper->nData);
 633     if( pWrapper->zData ){
 634       /* os_unix.c contains an assert() that fails if the caller attempts
 635       ** to read data from the 512-byte locking region of a file opened
 636       ** with the SQLITE_OPEN_MAIN_DB flag. This region of a database file
 637       ** never contains valid data anyhow. So avoid doing such a read here.
 638       **
 639       ** UPDATE: It also contains an assert() verifying that each call
 640       ** to the xRead() method reads less than 128KB of data.
 641       */
 642       i64 iOff;
 643
 644       memset(pWrapper->zData, 0, pWrapper->nData);
 645       for(iOff=0; iOff<pWrapper->iSize; iOff += 512){
 646         int nRead = (int)(pWrapper->iSize - iOff);
 647         if( nRead>512 ) nRead = 512;
 648         rc = sqlite3OsRead(pReal, &pWrapper->zData[iOff], nRead, iOff);
 649       }
 650     }else{
 651       rc = SQLITE_NOMEM;
 652     }
 653   }
 654   if( rc!=SQLITE_OK && pWrapper->pMethod ){
 655     sqlite3OsClose(pFile);
 656   }
 657   return rc;
 658 }
 659
 660 static int cfDelete(sqlite3_vfs *pCfVfs, const char *zPath, int dirSync){
 661   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 662   return pVfs->xDelete(pVfs, zPath, dirSync);
 663 }
 664 static int cfAccess(
 665   sqlite3_vfs *pCfVfs,
 666   const char *zPath,
 667   int flags,
 668   int *pResOut
 669 ){
 670   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 671   return pVfs->xAccess(pVfs, zPath, flags, pResOut);
 672 }
 673 static int cfFullPathname(
 674   sqlite3_vfs *pCfVfs,
 675   const char *zPath,
 676   int nPathOut,
 677   char *zPathOut
 678 ){
 679   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 680   return pVfs->xFullPathname(pVfs, zPath, nPathOut, zPathOut);
 681 }
 682 static void *cfDlOpen(sqlite3_vfs *pCfVfs, const char *zPath){
 683   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 684   return pVfs->xDlOpen(pVfs, zPath);
 685 }
 686 static void cfDlError(sqlite3_vfs *pCfVfs, int nByte, char *zErrMsg){
 687   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 688   pVfs->xDlError(pVfs, nByte, zErrMsg);
 689 }
 690 static void (*cfDlSym(sqlite3_vfs *pCfVfs, void *pH, const char *zSym))(void){
 691   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 692   return pVfs->xDlSym(pVfs, pH, zSym);
 693 }
 694 static void cfDlClose(sqlite3_vfs *pCfVfs, void *pHandle){
 695   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 696   pVfs->xDlClose(pVfs, pHandle);
 697 }
 698 static int cfRandomness(sqlite3_vfs *pCfVfs, int nByte, char *zBufOut){
 699   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 700   return pVfs->xRandomness(pVfs, nByte, zBufOut);
 701 }
 702 static int cfSleep(sqlite3_vfs *pCfVfs, int nMicro){
 703   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 704   return pVfs->xSleep(pVfs, nMicro);
 705 }
 706 static int cfCurrentTime(sqlite3_vfs *pCfVfs, double *pTimeOut){
 707   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 708   return pVfs->xCurrentTime(pVfs, pTimeOut);
 709 }
 710 static int cfGetLastError(sqlite3_vfs *pCfVfs, int n, char *z){
 711   sqlite3_vfs *pVfs = (sqlite3_vfs *)pCfVfs->pAppData;
 712   return pVfs->xGetLastError(pVfs, n, z);
 713 }
 714
 715 static int processDevSymArgs(
 716   Tcl_Interp *interp,
 717   int objc,
 718   Tcl_Obj *CONST objv[],
 719   int *piDeviceChar,
 720   int *piSectorSize
 721 ){
 722   struct DeviceFlag {
 723     char *zName;
 724     int iValue;
 725   } aFlag[] = {
 726     { "atomic",              SQLITE_IOCAP_ATOMIC                },
 727     { "atomic512",           SQLITE_IOCAP_ATOMIC512             },
 728     { "atomic1k",            SQLITE_IOCAP_ATOMIC1K              },
 729     { "atomic2k",            SQLITE_IOCAP_ATOMIC2K              },
 730     { "atomic4k",            SQLITE_IOCAP_ATOMIC4K              },
 731     { "atomic8k",            SQLITE_IOCAP_ATOMIC8K              },
 732     { "atomic16k",           SQLITE_IOCAP_ATOMIC16K             },
 733     { "atomic32k",           SQLITE_IOCAP_ATOMIC32K             },
 734     { "atomic64k",           SQLITE_IOCAP_ATOMIC64K             },
 735     { "sequential",          SQLITE_IOCAP_SEQUENTIAL            },
 736     { "safe_append",         SQLITE_IOCAP_SAFE_APPEND           },
 737     { "powersafe_overwrite", SQLITE_IOCAP_POWERSAFE_OVERWRITE   },
 738     { 0, 0 }
 739   };
 740
 741   int i;
 742   int iDc = 0;
 743   int iSectorSize = 0;
 744   int setSectorsize = 0;
 745   int setDeviceChar = 0;
 746
 747   for(i=0; i<objc; i+=2){
 748     int nOpt;
 749     char *zOpt = Tcl_GetStringFromObj(objv[i], &nOpt);
 750
 751     if( (nOpt>11 || nOpt<2 || strncmp("-sectorsize", zOpt, nOpt))
 752      && (nOpt>16 || nOpt<2 || strncmp("-characteristics", zOpt, nOpt))
 753     ){
 754       Tcl_AppendResult(interp,
 755         "Bad option: \"", zOpt,
 756         "\" - must be \"-characteristics\" or \"-sectorsize\"", 0
 757       );
 758       return TCL_ERROR;
 759     }
 760     if( i==objc-1 ){
 761       Tcl_AppendResult(interp, "Option requires an argument: \"", zOpt, "\"",0);
 762       return TCL_ERROR;
 763     }
 764
 765     if( zOpt[1]=='s' ){
 766       if( Tcl_GetIntFromObj(interp, objv[i+1], &iSectorSize) ){
 767         return TCL_ERROR;
 768       }
 769       setSectorsize = 1;
 770     }else{
 771       int j;
 772       Tcl_Obj **apObj;
 773       int nObj;
 774       if( Tcl_ListObjGetElements(interp, objv[i+1], &nObj, &apObj) ){
 775         return TCL_ERROR;
 776       }
 777       for(j=0; j<nObj; j++){
 778         int rc;
 779         int iChoice;
 780         Tcl_Obj *pFlag = Tcl_DuplicateObj(apObj[j]);
 781         Tcl_IncrRefCount(pFlag);
 782         Tcl_UtfToLower(Tcl_GetString(pFlag));
 783
 784         rc = Tcl_GetIndexFromObjStruct(
 785             interp, pFlag, aFlag, sizeof(aFlag[0]), "no such flag", 0, &iChoice
 786         );
 787         Tcl_DecrRefCount(pFlag);
 788         if( rc ){
 789           return TCL_ERROR;
 790         }
 791
 792         iDc |= aFlag[iChoice].iValue;
 793       }
 794       setDeviceChar = 1;
 795     }
 796   }
 797
 798   if( setDeviceChar ){
 799     *piDeviceChar = iDc;
 800   }
 801   if( setSectorsize ){
 802     *piSectorSize = iSectorSize;
 803   }
 804
 805   return TCL_OK;
 806 }
 807
 808 /*
 809 ** tclcmd:   sqlite3_crash_now
 810 **
 811 ** Simulate a crash immediately. This function does not return
 812 ** (writeListSync() calls exit(-1)).
 813 */
 814 static int SQLITE_TCLAPI crashNowCmd(
 815   void * clientData,
 816   Tcl_Interp *interp,
 817   int objc,
 818   Tcl_Obj *CONST objv[]
 819 ){
 820   if( objc!=1 ){
 821     Tcl_WrongNumArgs(interp, 1, objv, "");
 822     return TCL_ERROR;
 823   }
 824   writeListSync(0, 1);
 825   assert( 0 );
 826   return TCL_OK;
 827 }
 828
 829 /*
 830 ** tclcmd:   sqlite_crash_enable ENABLE
 831 **
 832 ** Parameter ENABLE must be a boolean value. If true, then the "crash"
 833 ** vfs is added to the system. If false, it is removed.
 834 */
 835 static int SQLITE_TCLAPI crashEnableCmd(
 836   void * clientData,
 837   Tcl_Interp *interp,
 838   int objc,
 839   Tcl_Obj *CONST objv[]
 840 ){
 841   int isEnable;
 842   static sqlite3_vfs crashVfs = {
 843     2,                  /* iVersion */
 844     0,                  /* szOsFile */
 845     0,                  /* mxPathname */
 846     0,                  /* pNext */
 847     "crash",            /* zName */
 848     0,                  /* pAppData */
 849
 850     cfOpen,               /* xOpen */
 851     cfDelete,             /* xDelete */
 852     cfAccess,             /* xAccess */
 853     cfFullPathname,       /* xFullPathname */
 854     cfDlOpen,             /* xDlOpen */
 855     cfDlError,            /* xDlError */
 856     cfDlSym,              /* xDlSym */
 857     cfDlClose,            /* xDlClose */
 858     cfRandomness,         /* xRandomness */
 859     cfSleep,              /* xSleep */
 860     cfCurrentTime,        /* xCurrentTime */
 861     cfGetLastError,       /* xGetLastError */
 862     0,                    /* xCurrentTimeInt64 */
 863   };
 864
 865   if( objc!=2 ){
 866     Tcl_WrongNumArgs(interp, 1, objv, "ENABLE");
 867     return TCL_ERROR;
 868   }
 869
 870   if( Tcl_GetBooleanFromObj(interp, objv[1], &isEnable) ){
 871     return TCL_ERROR;
 872   }
 873
 874   if( (isEnable && crashVfs.pAppData) || (!isEnable && !crashVfs.pAppData) ){
 875     return TCL_OK;
 876   }
 877
 878   if( crashVfs.pAppData==0 ){
 879     sqlite3_vfs *pOriginalVfs = sqlite3_vfs_find(0);
 880     crashVfs.mxPathname = pOriginalVfs->mxPathname;
 881     crashVfs.pAppData = (void *)pOriginalVfs;
 882     crashVfs.szOsFile = sizeof(CrashFile) + pOriginalVfs->szOsFile;
 883     sqlite3_vfs_register(&crashVfs, 0);
 884   }else{
 885     crashVfs.pAppData = 0;
 886     sqlite3_vfs_unregister(&crashVfs);
 887   }
 888
 889   return TCL_OK;
 890 }
 891
 892 /*
 893 ** tclcmd:   sqlite_crashparams ?OPTIONS? DELAY CRASHFILE
 894 **
 895 ** This procedure implements a TCL command that enables crash testing
 896 ** in testfixture.  Once enabled, crash testing cannot be disabled.
 897 **
 898 ** Available options are "-characteristics" and "-sectorsize". Both require
 899 ** an argument. For -sectorsize, this is the simulated sector size in
 900 ** bytes. For -characteristics, the argument must be a list of io-capability
 901 ** flags to simulate. Valid flags are "atomic", "atomic512", "atomic1K",
 902 ** "atomic2K", "atomic4K", "atomic8K", "atomic16K", "atomic32K",
 903 ** "atomic64K", "sequential" and "safe_append".
 904 **
 905 ** Example:
 906 **
 907 **   sqlite_crashparams -sect 1024 -char {atomic sequential} ./test.db 1
 908 **
 909 */
 910 static int SQLITE_TCLAPI crashParamsObjCmd(
 911   void * clientData,
 912   Tcl_Interp *interp,
 913   int objc,
 914   Tcl_Obj *CONST objv[]
 915 ){
 916   int iDelay;
 917   const char *zCrashFile;
 918   int nCrashFile, iDc, iSectorSize;
 919
 920   iDc = -1;
 921   iSectorSize = -1;
 922
 923   if( objc<3 ){
 924     Tcl_WrongNumArgs(interp, 1, objv, "?OPTIONS? DELAY CRASHFILE");
 925     goto error;
 926   }
 927
 928   zCrashFile = Tcl_GetStringFromObj(objv[objc-1], &nCrashFile);
 929   if( nCrashFile>=sizeof(g.zCrashFile) ){
 930     Tcl_AppendResult(interp, "Filename is too long: \"", zCrashFile, "\"", 0);
 931     goto error;
 932   }
 933   if( Tcl_GetIntFromObj(interp, objv[objc-2], &iDelay) ){
 934     goto error;
 935   }
 936
 937   if( processDevSymArgs(interp, objc-3, &objv[1], &iDc, &iSectorSize) ){
 938     return TCL_ERROR;
 939   }
 940
 941   if( iDc>=0 ){
 942     g.iDeviceCharacteristics = iDc;
 943   }
 944   if( iSectorSize>=0 ){
 945     g.iSectorSize = iSectorSize;
 946   }
 947
 948   g.iCrash = iDelay;
 949   memcpy(g.zCrashFile, zCrashFile, nCrashFile+1);
 950   sqlite3CrashTestEnable = 1;
 951   return TCL_OK;
 952
 953 error:
 954   return TCL_ERROR;
 955 }
 956
 957 static int SQLITE_TCLAPI devSymObjCmd(
 958   void * clientData,
 959   Tcl_Interp *interp,
 960   int objc,
 961   Tcl_Obj *CONST objv[]
 962 ){
 963   void devsym_register(int iDeviceChar, int iSectorSize);
 964
 965   int iDc = -1;
 966   int iSectorSize = -1;
 967
 968   if( processDevSymArgs(interp, objc-1, &objv[1], &iDc, &iSectorSize) ){
 969     return TCL_ERROR;
 970   }
 971   devsym_register(iDc, iSectorSize);
 972
 973   return TCL_OK;
 974
 975 }
 976
 977 /*
 978 ** tclcmd: unregister_devsim
 979 */
 980 static int SQLITE_TCLAPI dsUnregisterObjCmd(
 981   void * clientData,
 982   Tcl_Interp *interp,
 983   int objc,
 984   Tcl_Obj *CONST objv[]
 985 ){
 986   void devsym_unregister(void);
 987
 988   if( objc!=1 ){
 989     Tcl_WrongNumArgs(interp, 1, objv, "");
 990     return TCL_ERROR;
 991   }
 992
 993   devsym_unregister();
 994   return TCL_OK;
 995 }
 996
 997 /*
 998 ** tclcmd: register_jt_vfs ?-default? PARENT-VFS
 999 */
1000 static int SQLITE_TCLAPI jtObjCmd(
1001   void * clientData,
1002   Tcl_Interp *interp,
1003   int objc,
1004   Tcl_Obj *CONST objv[]
1005 ){
1006   int jt_register(char *, int);
1007   char *zParent = 0;
1008
1009   if( objc!=2 && objc!=3 ){
1010     Tcl_WrongNumArgs(interp, 1, objv, "?-default? PARENT-VFS");
1011     return TCL_ERROR;
1012   }
1013   zParent = Tcl_GetString(objv[1]);
1014   if( objc==3 ){
1015     if( strcmp(zParent, "-default") ){
1016       Tcl_AppendResult(interp,
1017           "bad option \"", zParent, "\": must be -default", 0
1018       );
1019       return TCL_ERROR;
1020     }
1021     zParent = Tcl_GetString(objv[2]);
1022   }
1023
1024   if( !(*zParent) ){
1025     zParent = 0;
1026   }
1027   if( jt_register(zParent, objc==3) ){
1028     Tcl_AppendResult(interp, "Error in jt_register", 0);
1029     return TCL_ERROR;
1030   }
1031
1032   return TCL_OK;
1033 }
1034
1035 /*
1036 ** tclcmd: unregister_jt_vfs
1037 */
1038 static int SQLITE_TCLAPI jtUnregisterObjCmd(
1039   void * clientData,
1040   Tcl_Interp *interp,
1041   int objc,
1042   Tcl_Obj *CONST objv[]
1043 ){
1044   void jt_unregister(void);
1045
1046   if( objc!=1 ){
1047     Tcl_WrongNumArgs(interp, 1, objv, "");
1048     return TCL_ERROR;
1049   }
1050
1051   jt_unregister();
1052   return TCL_OK;
1053 }
1054
1055 #endif /* SQLITE_OMIT_DISKIO */
1056
1057 /*
1058 ** This procedure registers the TCL procedures defined in this file.
1059 */
1060 int Sqlitetest6_Init(Tcl_Interp *interp){
1061 #ifndef SQLITE_OMIT_DISKIO
1062   Tcl_CreateObjCommand(interp, "sqlite3_crash_enable", crashEnableCmd, 0, 0);
1063   Tcl_CreateObjCommand(interp, "sqlite3_crashparams", crashParamsObjCmd, 0, 0);
1064   Tcl_CreateObjCommand(interp, "sqlite3_crash_now", crashNowCmd, 0, 0);
1065   Tcl_CreateObjCommand(interp, "sqlite3_simulate_device", devSymObjCmd, 0, 0);
1066   Tcl_CreateObjCommand(interp, "unregister_devsim", dsUnregisterObjCmd, 0, 0);
1067   Tcl_CreateObjCommand(interp, "register_jt_vfs", jtObjCmd, 0, 0);
1068   Tcl_CreateObjCommand(interp, "unregister_jt_vfs", jtUnregisterObjCmd, 0, 0);
1069 #endif
1070   return TCL_OK;
1071 }
1072
1073 #endif /* SQLITE_TEST */