src/test_demovfs.c

   1 /*
   2 ** 2010 April 7
   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 implements an example of a simple VFS implementation that
  14 ** omits complex features often not required or not possible on embedded
  15 ** platforms.  Code is included to buffer writes to the journal file,
  16 ** which can be a significant performance improvement on some embedded
  17 ** platforms.
  18 **
  19 ** OVERVIEW
  20 **
  21 **   The code in this file implements a minimal SQLite VFS that can be
  22 **   used on Linux and other posix-like operating systems. The following
  23 **   system calls are used:
  24 **
  25 **    File-system: access(), unlink(), getcwd()
  26 **    File IO:     open(), read(), write(), fsync(), close(), fstat()
  27 **    Other:       sleep(), usleep(), time()
  28 **
  29 **   The following VFS features are omitted:
  30 **
  31 **     1. File locking. The user must ensure that there is at most one
  32 **        connection to each database when using this VFS. Multiple
  33 **        connections to a single shared-cache count as a single connection
  34 **        for the purposes of the previous statement.
  35 **
  36 **     2. The loading of dynamic extensions (shared libraries).
  37 **
  38 **     3. Temporary files. The user must configure SQLite to use in-memory
  39 **        temp files when using this VFS. The easiest way to do this is to
  40 **        compile with:
  41 **
  42 **          -DSQLITE_TEMP_STORE=3
  43 **
  44 **     4. File truncation. As of version 3.6.24, SQLite may run without
  45 **        a working xTruncate() call, providing the user does not configure
  46 **        SQLite to use "journal_mode=truncate", or use both
  47 **        "journal_mode=persist" and ATTACHed databases.
  48 **
  49 **   It is assumed that the system uses UNIX-like path-names. Specifically,
  50 **   that '/' characters are used to separate path components and that
  51 **   a path-name is a relative path unless it begins with a '/'. And that
  52 **   no UTF-8 encoded paths are greater than 512 bytes in length.
  53 **
  54 ** JOURNAL WRITE-BUFFERING
  55 **
  56 **   To commit a transaction to the database, SQLite first writes rollback
  57 **   information into the journal file. This usually consists of 4 steps:
  58 **
  59 **     1. The rollback information is sequentially written into the journal
  60 **        file, starting at the start of the file.
  61 **     2. The journal file is synced to disk.
  62 **     3. A modification is made to the first few bytes of the journal file.
  63 **     4. The journal file is synced to disk again.
  64 **
  65 **   Most of the data is written in step 1 using a series of calls to the
  66 **   VFS xWrite() method. The buffers passed to the xWrite() calls are of
  67 **   various sizes. For example, as of version 3.6.24, when committing a
  68 **   transaction that modifies 3 pages of a database file that uses 4096
  69 **   byte pages residing on a media with 512 byte sectors, SQLite makes
  70 **   eleven calls to the xWrite() method to create the rollback journal,
  71 **   as follows:
  72 **
  73 **             Write offset | Bytes written
  74 **             ----------------------------
  75 **                        0            512
  76 **                      512              4
  77 **                      516           4096
  78 **                     4612              4
  79 **                     4616              4
  80 **                     4620           4096
  81 **                     8716              4
  82 **                     8720              4
  83 **                     8724           4096
  84 **                    12820              4
  85 **             ++++++++++++SYNC+++++++++++
  86 **                        0             12
  87 **             ++++++++++++SYNC+++++++++++
  88 **
  89 **   On many operating systems, this is an efficient way to write to a file.
  90 **   However, on some embedded systems that do not cache writes in OS
  91 **   buffers it is much more efficient to write data in blocks that are
  92 **   an integer multiple of the sector-size in size and aligned at the
  93 **   start of a sector.
  94 **
  95 **   To work around this, the code in this file allocates a fixed size
  96 **   buffer of SQLITE_DEMOVFS_BUFFERSZ using sqlite3_malloc() whenever a
  97 **   journal file is opened. It uses the buffer to coalesce sequential
  98 **   writes into aligned SQLITE_DEMOVFS_BUFFERSZ blocks. When SQLite
  99 **   invokes the xSync() method to sync the contents of the file to disk,
 100 **   all accumulated data is written out, even if it does not constitute
 101 **   a complete block. This means the actual IO to create the rollback
 102 **   journal for the example transaction above is this:
 103 **
 104 **             Write offset | Bytes written
 105 **             ----------------------------
 106 **                        0           8192
 107 **                     8192           4632
 108 **             ++++++++++++SYNC+++++++++++
 109 **                        0             12
 110 **             ++++++++++++SYNC+++++++++++
 111 **
 112 **   Much more efficient if the underlying OS is not caching write
 113 **   operations.
 114 */
 115
 116 #if !defined(SQLITE_TEST) || SQLITE_OS_UNIX
 117
 118 #include "sqlite3.h"
 119
 120 #include <assert.h>
 121 #include <string.h>
 122 #include <sys/types.h>
 123 #include <sys/stat.h>
 124 #include <sys/file.h>
 125 #include <sys/param.h>
 126 #include <unistd.h>
 127 #include <time.h>
 128 #include <errno.h>
 129 #include <fcntl.h>
 130
 131 /*
 132 ** Size of the write buffer used by journal files in bytes.
 133 */
 134 #ifndef SQLITE_DEMOVFS_BUFFERSZ
 135 # define SQLITE_DEMOVFS_BUFFERSZ 8192
 136 #endif
 137
 138 /*
 139 ** The maximum pathname length supported by this VFS.
 140 */
 141 #define MAXPATHNAME 512
 142
 143 /*
 144 ** When using this VFS, the sqlite3_file* handles that SQLite uses are
 145 ** actually pointers to instances of type DemoFile.
 146 */
 147 typedef struct DemoFile DemoFile;
 148 struct DemoFile {
 149   sqlite3_file base;              /* Base class. Must be first. */
 150   int fd;                         /* File descriptor */
 151
 152   char *aBuffer;                  /* Pointer to malloc'd buffer */
 153   int nBuffer;                    /* Valid bytes of data in zBuffer */
 154   sqlite3_int64 iBufferOfst;      /* Offset in file of zBuffer[0] */
 155 };
 156
 157 /*
 158 ** Write directly to the file passed as the first argument. Even if the
 159 ** file has a write-buffer (DemoFile.aBuffer), ignore it.
 160 */
 161 static int demoDirectWrite(
 162   DemoFile *p,                    /* File handle */
 163   const void *zBuf,               /* Buffer containing data to write */
 164   int iAmt,                       /* Size of data to write in bytes */
 165   sqlite_int64 iOfst              /* File offset to write to */
 166 ){
 167   off_t ofst;                     /* Return value from lseek() */
 168   size_t nWrite;                  /* Return value from write() */
 169
 170   ofst = lseek(p->fd, iOfst, SEEK_SET);
 171   if( ofst!=iOfst ){
 172     return SQLITE_IOERR_WRITE;
 173   }
 174
 175   nWrite = write(p->fd, zBuf, iAmt);
 176   if( nWrite!=iAmt ){
 177     return SQLITE_IOERR_WRITE;
 178   }
 179
 180   return SQLITE_OK;
 181 }
 182
 183 /*
 184 ** Flush the contents of the DemoFile.aBuffer buffer to disk. This is a
 185 ** no-op if this particular file does not have a buffer (i.e. it is not
 186 ** a journal file) or if the buffer is currently empty.
 187 */
 188 static int demoFlushBuffer(DemoFile *p){
 189   int rc = SQLITE_OK;
 190   if( p->nBuffer ){
 191     rc = demoDirectWrite(p, p->aBuffer, p->nBuffer, p->iBufferOfst);
 192     p->nBuffer = 0;
 193   }
 194   return rc;
 195 }
 196
 197 /*
 198 ** Close a file.
 199 */
 200 static int demoClose(sqlite3_file *pFile){
 201   int rc;
 202   DemoFile *p = (DemoFile*)pFile;
 203   rc = demoFlushBuffer(p);
 204   sqlite3_free(p->aBuffer);
 205   close(p->fd);
 206   return rc;
 207 }
 208
 209 /*
 210 ** Read data from a file.
 211 */
 212 static int demoRead(
 213   sqlite3_file *pFile,
 214   void *zBuf,
 215   int iAmt,
 216   sqlite_int64 iOfst
 217 ){
 218   DemoFile *p = (DemoFile*)pFile;
 219   off_t ofst;                     /* Return value from lseek() */
 220   int nRead;                      /* Return value from read() */
 221   int rc;                         /* Return code from demoFlushBuffer() */
 222
 223   /* Flush any data in the write buffer to disk in case this operation
 224   ** is trying to read data the file-region currently cached in the buffer.
 225   ** It would be possible to detect this case and possibly save an
 226   ** unnecessary write here, but in practice SQLite will rarely read from
 227   ** a journal file when there is data cached in the write-buffer.
 228   */
 229   rc = demoFlushBuffer(p);
 230   if( rc!=SQLITE_OK ){
 231     return rc;
 232   }
 233
 234   ofst = lseek(p->fd, iOfst, SEEK_SET);
 235   if( ofst!=iOfst ){
 236     return SQLITE_IOERR_READ;
 237   }
 238   nRead = read(p->fd, zBuf, iAmt);
 239
 240   if( nRead==iAmt ){
 241     return SQLITE_OK;
 242   }else if( nRead>=0 ){
 243     return SQLITE_IOERR_SHORT_READ;
 244   }
 245
 246   return SQLITE_IOERR_READ;
 247 }
 248
 249 /*
 250 ** Write data to a crash-file.
 251 */
 252 static int demoWrite(
 253   sqlite3_file *pFile,
 254   const void *zBuf,
 255   int iAmt,
 256   sqlite_int64 iOfst
 257 ){
 258   DemoFile *p = (DemoFile*)pFile;
 259
 260   if( p->aBuffer ){
 261     char *z = (char *)zBuf;       /* Pointer to remaining data to write */
 262     int n = iAmt;                 /* Number of bytes at z */
 263     sqlite3_int64 i = iOfst;      /* File offset to write to */
 264
 265     while( n>0 ){
 266       int nCopy;                  /* Number of bytes to copy into buffer */
 267
 268       /* If the buffer is full, or if this data is not being written directly
 269       ** following the data already buffered, flush the buffer. Flushing
 270       ** the buffer is a no-op if it is empty.
 271       */
 272       if( p->nBuffer==SQLITE_DEMOVFS_BUFFERSZ || p->iBufferOfst+p->nBuffer!=i ){
 273         int rc = demoFlushBuffer(p);
 274         if( rc!=SQLITE_OK ){
 275           return rc;
 276         }
 277       }
 278       assert( p->nBuffer==0 || p->iBufferOfst+p->nBuffer==i );
 279       p->iBufferOfst = i - p->nBuffer;
 280
 281       /* Copy as much data as possible into the buffer. */
 282       nCopy = SQLITE_DEMOVFS_BUFFERSZ - p->nBuffer;
 283       if( nCopy>n ){
 284         nCopy = n;
 285       }
 286       memcpy(&p->aBuffer[p->nBuffer], z, nCopy);
 287       p->nBuffer += nCopy;
 288
 289       n -= nCopy;
 290       i += nCopy;
 291       z += nCopy;
 292     }
 293   }else{
 294     return demoDirectWrite(p, zBuf, iAmt, iOfst);
 295   }
 296
 297   return SQLITE_OK;
 298 }
 299
 300 /*
 301 ** Truncate a file. This is a no-op for this VFS (see header comments at
 302 ** the top of the file).
 303 */
 304 static int demoTruncate(sqlite3_file *pFile, sqlite_int64 size){
 305 #if 0
 306   if( ftruncate(((DemoFile *)pFile)->fd, size) ) return SQLITE_IOERR_TRUNCATE;
 307 #endif
 308   return SQLITE_OK;
 309 }
 310
 311 /*
 312 ** Sync the contents of the file to the persistent media.
 313 */
 314 static int demoSync(sqlite3_file *pFile, int flags){
 315   DemoFile *p = (DemoFile*)pFile;
 316   int rc;
 317
 318   rc = demoFlushBuffer(p);
 319   if( rc!=SQLITE_OK ){
 320     return rc;
 321   }
 322
 323   rc = fsync(p->fd);
 324   return (rc==0 ? SQLITE_OK : SQLITE_IOERR_FSYNC);
 325 }
 326
 327 /*
 328 ** Write the size of the file in bytes to *pSize.
 329 */
 330 static int demoFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){
 331   DemoFile *p = (DemoFile*)pFile;
 332   int rc;                         /* Return code from fstat() call */
 333   struct stat sStat;              /* Output of fstat() call */
 334
 335   /* Flush the contents of the buffer to disk. As with the flush in the
 336   ** demoRead() method, it would be possible to avoid this and save a write
 337   ** here and there. But in practice this comes up so infrequently it is
 338   ** not worth the trouble.
 339   */
 340   rc = demoFlushBuffer(p);
 341   if( rc!=SQLITE_OK ){
 342     return rc;
 343   }
 344
 345   rc = fstat(p->fd, &sStat);
 346   if( rc!=0 ) return SQLITE_IOERR_FSTAT;
 347   *pSize = sStat.st_size;
 348   return SQLITE_OK;
 349 }
 350
 351 /*
 352 ** Locking functions. The xLock() and xUnlock() methods are both no-ops.
 353 ** The xCheckReservedLock() always indicates that no other process holds
 354 ** a reserved lock on the database file. This ensures that if a hot-journal
 355 ** file is found in the file-system it is rolled back.
 356 */
 357 static int demoLock(sqlite3_file *pFile, int eLock){
 358   return SQLITE_OK;
 359 }
 360 static int demoUnlock(sqlite3_file *pFile, int eLock){
 361   return SQLITE_OK;
 362 }
 363 static int demoCheckReservedLock(sqlite3_file *pFile, int *pResOut){
 364   *pResOut = 0;
 365   return SQLITE_OK;
 366 }
 367
 368 /*
 369 ** No xFileControl() verbs are implemented by this VFS.
 370 */
 371 static int demoFileControl(sqlite3_file *pFile, int op, void *pArg){
 372   return SQLITE_OK;
 373 }
 374
 375 /*
 376 ** The xSectorSize() and xDeviceCharacteristics() methods. These two
 377 ** may return special values allowing SQLite to optimize file-system
 378 ** access to some extent. But it is also safe to simply return 0.
 379 */
 380 static int demoSectorSize(sqlite3_file *pFile){
 381   return 0;
 382 }
 383 static int demoDeviceCharacteristics(sqlite3_file *pFile){
 384   return 0;
 385 }
 386
 387 /*
 388 ** Open a file handle.
 389 */
 390 static int demoOpen(
 391   sqlite3_vfs *pVfs,              /* VFS */
 392   const char *zName,              /* File to open, or 0 for a temp file */
 393   sqlite3_file *pFile,            /* Pointer to DemoFile struct to populate */
 394   int flags,                      /* Input SQLITE_OPEN_XXX flags */
 395   int *pOutFlags                  /* Output SQLITE_OPEN_XXX flags (or NULL) */
 396 ){
 397   static const sqlite3_io_methods demoio = {
 398     1,                            /* iVersion */
 399     demoClose,                    /* xClose */
 400     demoRead,                     /* xRead */
 401     demoWrite,                    /* xWrite */
 402     demoTruncate,                 /* xTruncate */
 403     demoSync,                     /* xSync */
 404     demoFileSize,                 /* xFileSize */
 405     demoLock,                     /* xLock */
 406     demoUnlock,                   /* xUnlock */
 407     demoCheckReservedLock,        /* xCheckReservedLock */
 408     demoFileControl,              /* xFileControl */
 409     demoSectorSize,               /* xSectorSize */
 410     demoDeviceCharacteristics     /* xDeviceCharacteristics */
 411   };
 412
 413   DemoFile *p = (DemoFile*)pFile; /* Populate this structure */
 414   int oflags = 0;                 /* flags to pass to open() call */
 415   char *aBuf = 0;
 416
 417   if( zName==0 ){
 418     return SQLITE_IOERR;
 419   }
 420
 421   if( flags&SQLITE_OPEN_MAIN_JOURNAL ){
 422     aBuf = (char *)sqlite3_malloc(SQLITE_DEMOVFS_BUFFERSZ);
 423     if( !aBuf ){
 424       return SQLITE_NOMEM;
 425     }
 426   }
 427
 428   if( flags&SQLITE_OPEN_EXCLUSIVE ) oflags |= O_EXCL;
 429   if( flags&SQLITE_OPEN_CREATE )    oflags |= O_CREAT;
 430   if( flags&SQLITE_OPEN_READONLY )  oflags |= O_RDONLY;
 431   if( flags&SQLITE_OPEN_READWRITE ) oflags |= O_RDWR;
 432
 433   memset(p, 0, sizeof(DemoFile));
 434   p->fd = open(zName, oflags, 0600);
 435   if( p->fd<0 ){
 436     sqlite3_free(aBuf);
 437     return SQLITE_CANTOPEN;
 438   }
 439   p->aBuffer = aBuf;
 440
 441   if( pOutFlags ){
 442     *pOutFlags = flags;
 443   }
 444   p->base.pMethods = &demoio;
 445   return SQLITE_OK;
 446 }
 447
 448 /*
 449 ** Delete the file identified by argument zPath. If the dirSync parameter
 450 ** is non-zero, then ensure the file-system modification to delete the
 451 ** file has been synced to disk before returning.
 452 */
 453 static int demoDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
 454   int rc;                         /* Return code */
 455
 456   rc = unlink(zPath);
 457   if( rc!=0 && errno==ENOENT ) return SQLITE_OK;
 458
 459   if( rc==0 && dirSync ){
 460     int dfd;                      /* File descriptor open on directory */
 461     int i;                        /* Iterator variable */
 462     char zDir[MAXPATHNAME+1];     /* Name of directory containing file zPath */
 463
 464     /* Figure out the directory name from the path of the file deleted. */
 465     sqlite3_snprintf(MAXPATHNAME, zDir, "%s", zPath);
 466     zDir[MAXPATHNAME] = '\0';
 467     for(i=strlen(zDir); i>1 && zDir[i]!='/'; i++);
 468     zDir[i] = '\0';
 469
 470     /* Open a file-descriptor on the directory. Sync. Close. */
 471     dfd = open(zDir, O_RDONLY, 0);
 472     if( dfd<0 ){
 473       rc = -1;
 474     }else{
 475       rc = fsync(dfd);
 476       close(dfd);
 477     }
 478   }
 479   return (rc==0 ? SQLITE_OK : SQLITE_IOERR_DELETE);
 480 }
 481
 482 #ifndef F_OK
 483 # define F_OK 0
 484 #endif
 485 #ifndef R_OK
 486 # define R_OK 4
 487 #endif
 488 #ifndef W_OK
 489 # define W_OK 2
 490 #endif
 491
 492 /*
 493 ** Query the file-system to see if the named file exists, is readable or
 494 ** is both readable and writable.
 495 */
 496 static int demoAccess(
 497   sqlite3_vfs *pVfs,
 498   const char *zPath,
 499   int flags,
 500   int *pResOut
 501 ){
 502   int rc;                         /* access() return code */
 503   int eAccess = F_OK;             /* Second argument to access() */
 504
 505   assert( flags==SQLITE_ACCESS_EXISTS       /* access(zPath, F_OK) */
 506        || flags==SQLITE_ACCESS_READ         /* access(zPath, R_OK) */
 507        || flags==SQLITE_ACCESS_READWRITE    /* access(zPath, R_OK|W_OK) */
 508   );
 509
 510   if( flags==SQLITE_ACCESS_READWRITE ) eAccess = R_OK|W_OK;
 511   if( flags==SQLITE_ACCESS_READ )      eAccess = R_OK;
 512
 513   rc = access(zPath, eAccess);
 514   *pResOut = (rc==0);
 515   return SQLITE_OK;
 516 }
 517
 518 /*
 519 ** Argument zPath points to a nul-terminated string containing a file path.
 520 ** If zPath is an absolute path, then it is copied as is into the output
 521 ** buffer. Otherwise, if it is a relative path, then the equivalent full
 522 ** path is written to the output buffer.
 523 **
 524 ** This function assumes that paths are UNIX style. Specifically, that:
 525 **
 526 **   1. Path components are separated by a '/'. and
 527 **   2. Full paths begin with a '/' character.
 528 */
 529 static int demoFullPathname(
 530   sqlite3_vfs *pVfs,              /* VFS */
 531   const char *zPath,              /* Input path (possibly a relative path) */
 532   int nPathOut,                   /* Size of output buffer in bytes */
 533   char *zPathOut                  /* Pointer to output buffer */
 534 ){
 535   char zDir[MAXPATHNAME+1];
 536   if( zPath[0]=='/' ){
 537     zDir[0] = '\0';
 538   }else{
 539     if( getcwd(zDir, sizeof(zDir))==0 ) return SQLITE_IOERR;
 540   }
 541   zDir[MAXPATHNAME] = '\0';
 542
 543   sqlite3_snprintf(nPathOut, zPathOut, "%s/%s", zDir, zPath);
 544   zPathOut[nPathOut-1] = '\0';
 545
 546   return SQLITE_OK;
 547 }
 548
 549 /*
 550 ** The following four VFS methods:
 551 **
 552 **   xDlOpen
 553 **   xDlError
 554 **   xDlSym
 555 **   xDlClose
 556 **
 557 ** are supposed to implement the functionality needed by SQLite to load
 558 ** extensions compiled as shared objects. This simple VFS does not support
 559 ** this functionality, so the following functions are no-ops.
 560 */
 561 static void *demoDlOpen(sqlite3_vfs *pVfs, const char *zPath){
 562   return 0;
 563 }
 564 static void demoDlError(sqlite3_vfs *pVfs, int nByte, char *zErrMsg){
 565   sqlite3_snprintf(nByte, zErrMsg, "Loadable extensions are not supported");
 566   zErrMsg[nByte-1] = '\0';
 567 }
 568 static void (*demoDlSym(sqlite3_vfs *pVfs, void *pH, const char *z))(void){
 569   return 0;
 570 }
 571 static void demoDlClose(sqlite3_vfs *pVfs, void *pHandle){
 572   return;
 573 }
 574
 575 /*
 576 ** Parameter zByte points to a buffer nByte bytes in size. Populate this
 577 ** buffer with pseudo-random data.
 578 */
 579 static int demoRandomness(sqlite3_vfs *pVfs, int nByte, char *zByte){
 580   return SQLITE_OK;
 581 }
 582
 583 /*
 584 ** Sleep for at least nMicro microseconds. Return the (approximate) number
 585 ** of microseconds slept for.
 586 */
 587 static int demoSleep(sqlite3_vfs *pVfs, int nMicro){
 588   sleep(nMicro / 1000000);
 589   usleep(nMicro % 1000000);
 590   return nMicro;
 591 }
 592
 593 /*
 594 ** Set *pTime to the current UTC time expressed as a Julian day. Return
 595 ** SQLITE_OK if successful, or an error code otherwise.
 596 **
 597 **   http://en.wikipedia.org/wiki/Julian_day
 598 **
 599 ** This implementation is not very good. The current time is rounded to
 600 ** an integer number of seconds. Also, assuming time_t is a signed 32-bit
 601 ** value, it will stop working some time in the year 2038 AD (the so-called
 602 ** "year 2038" problem that afflicts systems that store time this way).
 603 */
 604 static int demoCurrentTime(sqlite3_vfs *pVfs, double *pTime){
 605   time_t t = time(0);
 606   *pTime = t/86400.0 + 2440587.5;
 607   return SQLITE_OK;
 608 }
 609
 610 /*
 611 ** This function returns a pointer to the VFS implemented in this file.
 612 ** To make the VFS available to SQLite:
 613 **
 614 **   sqlite3_vfs_register(sqlite3_demovfs(), 0);
 615 */
 616 sqlite3_vfs *sqlite3_demovfs(void){
 617   static sqlite3_vfs demovfs = {
 618     1,                            /* iVersion */
 619     sizeof(DemoFile),             /* szOsFile */
 620     MAXPATHNAME,                  /* mxPathname */
 621     0,                            /* pNext */
 622     "demo",                       /* zName */
 623     0,                            /* pAppData */
 624     demoOpen,                     /* xOpen */
 625     demoDelete,                   /* xDelete */
 626     demoAccess,                   /* xAccess */
 627     demoFullPathname,             /* xFullPathname */
 628     demoDlOpen,                   /* xDlOpen */
 629     demoDlError,                  /* xDlError */
 630     demoDlSym,                    /* xDlSym */
 631     demoDlClose,                  /* xDlClose */
 632     demoRandomness,               /* xRandomness */
 633     demoSleep,                    /* xSleep */
 634     demoCurrentTime,              /* xCurrentTime */
 635   };
 636   return &demovfs;
 637 }
 638
 639 #endif /* !defined(SQLITE_TEST) || SQLITE_OS_UNIX */
 640
 641
 642 #ifdef SQLITE_TEST
 643
 644 #if defined(INCLUDE_SQLITE_TCL_H)
 645 #  include "sqlite_tcl.h"
 646 #else
 647 #  include "tcl.h"
 648 #  ifndef SQLITE_TCLAPI
 649 #    define SQLITE_TCLAPI
 650 #  endif
 651 #endif
 652
 653 #if SQLITE_OS_UNIX
 654 static int SQLITE_TCLAPI register_demovfs(
 655   ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
 656   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
 657   int objc,              /* Number of arguments */
 658   Tcl_Obj *CONST objv[]  /* Command arguments */
 659 ){
 660   sqlite3_vfs_register(sqlite3_demovfs(), 1);
 661   return TCL_OK;
 662 }
 663 static int SQLITE_TCLAPI unregister_demovfs(
 664   ClientData clientData, /* Pointer to sqlite3_enable_XXX function */
 665   Tcl_Interp *interp,    /* The TCL interpreter that invoked this command */
 666   int objc,              /* Number of arguments */
 667   Tcl_Obj *CONST objv[]  /* Command arguments */
 668 ){
 669   sqlite3_vfs_unregister(sqlite3_demovfs());
 670   return TCL_OK;
 671 }
 672
 673 /*
 674 ** Register commands with the TCL interpreter.
 675 */
 676 int Sqlitetest_demovfs_Init(Tcl_Interp *interp){
 677   Tcl_CreateObjCommand(interp, "register_demovfs", register_demovfs, 0, 0);
 678   Tcl_CreateObjCommand(interp, "unregister_demovfs", unregister_demovfs, 0, 0);
 679   return TCL_OK;
 680 }
 681
 682 #else
 683 int Sqlitetest_demovfs_Init(Tcl_Interp *interp){ return TCL_OK; }
 684 #endif
 685
 686 #endif /* SQLITE_TEST */