1/* 2** 2007 September 14 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** OVERVIEW: 14** 15** This file contains some example code demonstrating how the SQLite 16** vfs feature can be used to have SQLite operate directly on an 17** embedded media, without using an intermediate file system. 18** 19** Because this is only a demo designed to run on a workstation, the 20** underlying media is simulated using a regular file-system file. The 21** size of the file is fixed when it is first created (default size 10 MB). 22** From SQLite's point of view, this space is used to store a single 23** database file and the journal file. 24** 25** Any statement journal created is stored in volatile memory obtained 26** from sqlite3_malloc(). Any attempt to create a temporary database file 27** will fail (SQLITE_IOERR). To prevent SQLite from attempting this, 28** it should be configured to store all temporary database files in 29** main memory (see pragma "temp_store" or the SQLITE_TEMP_STORE compile 30** time option). 31** 32** ASSUMPTIONS: 33** 34** After it has been created, the blob file is accessed using the 35** following three functions only: 36** 37** mediaRead(); - Read a 512 byte block from the file. 38** mediaWrite(); - Write a 512 byte block to the file. 39** mediaSync(); - Tell the media hardware to sync. 40** 41** It is assumed that these can be easily implemented by any "real" 42** media vfs driver adapting this code. 43** 44** FILE FORMAT: 45** 46** The basic principle is that the "database file" is stored at the 47** beginning of the 10 MB blob and grows in a forward direction. The 48** "journal file" is stored at the end of the 10MB blob and grows 49** in the reverse direction. If, during a transaction, insufficient 50** space is available to expand either the journal or database file, 51** an SQLITE_FULL error is returned. The database file is never allowed 52** to consume more than 90% of the blob space. If SQLite tries to 53** create a file larger than this, SQLITE_FULL is returned. 54** 55** No allowance is made for "wear-leveling", as is required by. 56** embedded devices in the absence of equivalent hardware features. 57** 58** The first 512 block byte of the file is reserved for storing the 59** size of the "database file". It is updated as part of the sync() 60** operation. On startup, it can only be trusted if no journal file 61** exists. If a journal-file does exist, then it stores the real size 62** of the database region. The second and subsequent blocks store the 63** actual database content. 64** 65** The size of the "journal file" is not stored persistently in the 66** file. When the system is running, the size of the journal file is 67** stored in volatile memory. When recovering from a crash, this vfs 68** reports a very large size for the journal file. The normal journal 69** header and checksum mechanisms serve to prevent SQLite from 70** processing any data that lies past the logical end of the journal. 71** 72** When SQLite calls OsDelete() to delete the journal file, the final 73** 512 bytes of the blob (the area containing the first journal header) 74** are zeroed. 75** 76** LOCKING: 77** 78** File locking is a no-op. Only one connection may be open at any one 79** time using this demo vfs. 80*/ 81 82#include "sqlite3.h" 83#include <assert.h> 84#include <string.h> 85 86/* 87** Maximum pathname length supported by the fs backend. 88*/ 89#define BLOCKSIZE 512 90#define BLOBSIZE 10485760 91 92/* 93** Name used to identify this VFS. 94*/ 95#define FS_VFS_NAME "fs" 96 97typedef struct fs_real_file fs_real_file; 98struct fs_real_file { 99 sqlite3_file *pFile; 100 const char *zName; 101 int nDatabase; /* Current size of database region */ 102 int nJournal; /* Current size of journal region */ 103 int nBlob; /* Total size of allocated blob */ 104 int nRef; /* Number of pointers to this structure */ 105 fs_real_file *pNext; 106 fs_real_file **ppThis; 107}; 108 109typedef struct fs_file fs_file; 110struct fs_file { 111 sqlite3_file base; 112 int eType; 113 fs_real_file *pReal; 114}; 115 116typedef struct tmp_file tmp_file; 117struct tmp_file { 118 sqlite3_file base; 119 int nSize; 120 int nAlloc; 121 char *zAlloc; 122}; 123 124/* Values for fs_file.eType. */ 125#define DATABASE_FILE 1 126#define JOURNAL_FILE 2 127 128/* 129** Method declarations for fs_file. 130*/ 131static int fsClose(sqlite3_file*); 132static int fsRead(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst); 133static int fsWrite(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst); 134static int fsTruncate(sqlite3_file*, sqlite3_int64 size); 135static int fsSync(sqlite3_file*, int flags); 136static int fsFileSize(sqlite3_file*, sqlite3_int64 *pSize); 137static int fsLock(sqlite3_file*, int); 138static int fsUnlock(sqlite3_file*, int); 139static int fsCheckReservedLock(sqlite3_file*, int *pResOut); 140static int fsFileControl(sqlite3_file*, int op, void *pArg); 141static int fsSectorSize(sqlite3_file*); 142static int fsDeviceCharacteristics(sqlite3_file*); 143 144/* 145** Method declarations for tmp_file. 146*/ 147static int tmpClose(sqlite3_file*); 148static int tmpRead(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst); 149static int tmpWrite(sqlite3_file*, const void*, int iAmt, sqlite3_int64 iOfst); 150static int tmpTruncate(sqlite3_file*, sqlite3_int64 size); 151static int tmpSync(sqlite3_file*, int flags); 152static int tmpFileSize(sqlite3_file*, sqlite3_int64 *pSize); 153static int tmpLock(sqlite3_file*, int); 154static int tmpUnlock(sqlite3_file*, int); 155static int tmpCheckReservedLock(sqlite3_file*, int *pResOut); 156static int tmpFileControl(sqlite3_file*, int op, void *pArg); 157static int tmpSectorSize(sqlite3_file*); 158static int tmpDeviceCharacteristics(sqlite3_file*); 159 160/* 161** Method declarations for fs_vfs. 162*/ 163static int fsOpen(sqlite3_vfs*, const char *, sqlite3_file*, int , int *); 164static int fsDelete(sqlite3_vfs*, const char *zName, int syncDir); 165static int fsAccess(sqlite3_vfs*, const char *zName, int flags, int *); 166static int fsFullPathname(sqlite3_vfs*, const char *zName, int nOut,char *zOut); 167static void *fsDlOpen(sqlite3_vfs*, const char *zFilename); 168static void fsDlError(sqlite3_vfs*, int nByte, char *zErrMsg); 169static void (*fsDlSym(sqlite3_vfs*,void*, const char *zSymbol))(void); 170static void fsDlClose(sqlite3_vfs*, void*); 171static int fsRandomness(sqlite3_vfs*, int nByte, char *zOut); 172static int fsSleep(sqlite3_vfs*, int microseconds); 173static int fsCurrentTime(sqlite3_vfs*, double*); 174 175 176typedef struct fs_vfs_t fs_vfs_t; 177struct fs_vfs_t { 178 sqlite3_vfs base; 179 fs_real_file *pFileList; 180 sqlite3_vfs *pParent; 181}; 182 183static fs_vfs_t fs_vfs = { 184 { 185 1, /* iVersion */ 186 0, /* szOsFile */ 187 0, /* mxPathname */ 188 0, /* pNext */ 189 FS_VFS_NAME, /* zName */ 190 0, /* pAppData */ 191 fsOpen, /* xOpen */ 192 fsDelete, /* xDelete */ 193 fsAccess, /* xAccess */ 194 fsFullPathname, /* xFullPathname */ 195 fsDlOpen, /* xDlOpen */ 196 fsDlError, /* xDlError */ 197 fsDlSym, /* xDlSym */ 198 fsDlClose, /* xDlClose */ 199 fsRandomness, /* xRandomness */ 200 fsSleep, /* xSleep */ 201 fsCurrentTime, /* xCurrentTime */ 202 0 /* xCurrentTimeInt64 */ 203 }, 204 0, /* pFileList */ 205 0 /* pParent */ 206}; 207 208static sqlite3_io_methods fs_io_methods = { 209 1, /* iVersion */ 210 fsClose, /* xClose */ 211 fsRead, /* xRead */ 212 fsWrite, /* xWrite */ 213 fsTruncate, /* xTruncate */ 214 fsSync, /* xSync */ 215 fsFileSize, /* xFileSize */ 216 fsLock, /* xLock */ 217 fsUnlock, /* xUnlock */ 218 fsCheckReservedLock, /* xCheckReservedLock */ 219 fsFileControl, /* xFileControl */ 220 fsSectorSize, /* xSectorSize */ 221 fsDeviceCharacteristics, /* xDeviceCharacteristics */ 222 0, /* xShmMap */ 223 0, /* xShmLock */ 224 0, /* xShmBarrier */ 225 0 /* xShmUnmap */ 226}; 227 228 229static sqlite3_io_methods tmp_io_methods = { 230 1, /* iVersion */ 231 tmpClose, /* xClose */ 232 tmpRead, /* xRead */ 233 tmpWrite, /* xWrite */ 234 tmpTruncate, /* xTruncate */ 235 tmpSync, /* xSync */ 236 tmpFileSize, /* xFileSize */ 237 tmpLock, /* xLock */ 238 tmpUnlock, /* xUnlock */ 239 tmpCheckReservedLock, /* xCheckReservedLock */ 240 tmpFileControl, /* xFileControl */ 241 tmpSectorSize, /* xSectorSize */ 242 tmpDeviceCharacteristics, /* xDeviceCharacteristics */ 243 0, /* xShmMap */ 244 0, /* xShmLock */ 245 0, /* xShmBarrier */ 246 0 /* xShmUnmap */ 247}; 248 249/* Useful macros used in several places */ 250#define MIN(x,y) ((x)<(y)?(x):(y)) 251#define MAX(x,y) ((x)>(y)?(x):(y)) 252 253 254/* 255** Close a tmp-file. 256*/ 257static int tmpClose(sqlite3_file *pFile){ 258 tmp_file *pTmp = (tmp_file *)pFile; 259 sqlite3_free(pTmp->zAlloc); 260 return SQLITE_OK; 261} 262 263/* 264** Read data from a tmp-file. 265*/ 266static int tmpRead( 267 sqlite3_file *pFile, 268 void *zBuf, 269 int iAmt, 270 sqlite_int64 iOfst 271){ 272 tmp_file *pTmp = (tmp_file *)pFile; 273 if( (iAmt+iOfst)>pTmp->nSize ){ 274 return SQLITE_IOERR_SHORT_READ; 275 } 276 memcpy(zBuf, &pTmp->zAlloc[iOfst], iAmt); 277 return SQLITE_OK; 278} 279 280/* 281** Write data to a tmp-file. 282*/ 283static int tmpWrite( 284 sqlite3_file *pFile, 285 const void *zBuf, 286 int iAmt, 287 sqlite_int64 iOfst 288){ 289 tmp_file *pTmp = (tmp_file *)pFile; 290 if( (iAmt+iOfst)>pTmp->nAlloc ){ 291 int nNew = 2*(iAmt+iOfst+pTmp->nAlloc); 292 char *zNew = sqlite3_realloc(pTmp->zAlloc, nNew); 293 if( !zNew ){ 294 return SQLITE_NOMEM; 295 } 296 pTmp->zAlloc = zNew; 297 pTmp->nAlloc = nNew; 298 } 299 memcpy(&pTmp->zAlloc[iOfst], zBuf, iAmt); 300 pTmp->nSize = MAX(pTmp->nSize, iOfst+iAmt); 301 return SQLITE_OK; 302} 303 304/* 305** Truncate a tmp-file. 306*/ 307static int tmpTruncate(sqlite3_file *pFile, sqlite_int64 size){ 308 tmp_file *pTmp = (tmp_file *)pFile; 309 pTmp->nSize = MIN(pTmp->nSize, size); 310 return SQLITE_OK; 311} 312 313/* 314** Sync a tmp-file. 315*/ 316static int tmpSync(sqlite3_file *pFile, int flags){ 317 return SQLITE_OK; 318} 319 320/* 321** Return the current file-size of a tmp-file. 322*/ 323static int tmpFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){ 324 tmp_file *pTmp = (tmp_file *)pFile; 325 *pSize = pTmp->nSize; 326 return SQLITE_OK; 327} 328 329/* 330** Lock a tmp-file. 331*/ 332static int tmpLock(sqlite3_file *pFile, int eLock){ 333 return SQLITE_OK; 334} 335 336/* 337** Unlock a tmp-file. 338*/ 339static int tmpUnlock(sqlite3_file *pFile, int eLock){ 340 return SQLITE_OK; 341} 342 343/* 344** Check if another file-handle holds a RESERVED lock on a tmp-file. 345*/ 346static int tmpCheckReservedLock(sqlite3_file *pFile, int *pResOut){ 347 *pResOut = 0; 348 return SQLITE_OK; 349} 350 351/* 352** File control method. For custom operations on a tmp-file. 353*/ 354static int tmpFileControl(sqlite3_file *pFile, int op, void *pArg){ 355 return SQLITE_OK; 356} 357 358/* 359** Return the sector-size in bytes for a tmp-file. 360*/ 361static int tmpSectorSize(sqlite3_file *pFile){ 362 return 0; 363} 364 365/* 366** Return the device characteristic flags supported by a tmp-file. 367*/ 368static int tmpDeviceCharacteristics(sqlite3_file *pFile){ 369 return 0; 370} 371 372/* 373** Close an fs-file. 374*/ 375static int fsClose(sqlite3_file *pFile){ 376 int rc = SQLITE_OK; 377 fs_file *p = (fs_file *)pFile; 378 fs_real_file *pReal = p->pReal; 379 380 /* Decrement the real_file ref-count. */ 381 pReal->nRef--; 382 assert(pReal->nRef>=0); 383 384 /* When the ref-count reaches 0, destroy the structure */ 385 if( pReal->nRef==0 ){ 386 *pReal->ppThis = pReal->pNext; 387 if( pReal->pNext ){ 388 pReal->pNext->ppThis = pReal->ppThis; 389 } 390 rc = pReal->pFile->pMethods->xClose(pReal->pFile); 391 sqlite3_free(pReal); 392 } 393 394 return rc; 395} 396 397/* 398** Read data from an fs-file. 399*/ 400static int fsRead( 401 sqlite3_file *pFile, 402 void *zBuf, 403 int iAmt, 404 sqlite_int64 iOfst 405){ 406 int rc = SQLITE_OK; 407 fs_file *p = (fs_file *)pFile; 408 fs_real_file *pReal = p->pReal; 409 sqlite3_file *pF = pReal->pFile; 410 411 if( (p->eType==DATABASE_FILE && (iAmt+iOfst)>pReal->nDatabase) 412 || (p->eType==JOURNAL_FILE && (iAmt+iOfst)>pReal->nJournal) 413 ){ 414 rc = SQLITE_IOERR_SHORT_READ; 415 }else if( p->eType==DATABASE_FILE ){ 416 rc = pF->pMethods->xRead(pF, zBuf, iAmt, iOfst+BLOCKSIZE); 417 }else{ 418 /* Journal file. */ 419 int iRem = iAmt; 420 int iBuf = 0; 421 int ii = iOfst; 422 while( iRem>0 && rc==SQLITE_OK ){ 423 int iRealOff = pReal->nBlob - BLOCKSIZE*((ii/BLOCKSIZE)+1) + ii%BLOCKSIZE; 424 int iRealAmt = MIN(iRem, BLOCKSIZE - (iRealOff%BLOCKSIZE)); 425 426 rc = pF->pMethods->xRead(pF, &((char *)zBuf)[iBuf], iRealAmt, iRealOff); 427 ii += iRealAmt; 428 iBuf += iRealAmt; 429 iRem -= iRealAmt; 430 } 431 } 432 433 return rc; 434} 435 436/* 437** Write data to an fs-file. 438*/ 439static int fsWrite( 440 sqlite3_file *pFile, 441 const void *zBuf, 442 int iAmt, 443 sqlite_int64 iOfst 444){ 445 int rc = SQLITE_OK; 446 fs_file *p = (fs_file *)pFile; 447 fs_real_file *pReal = p->pReal; 448 sqlite3_file *pF = pReal->pFile; 449 450 if( p->eType==DATABASE_FILE ){ 451 if( (iAmt+iOfst+BLOCKSIZE)>(pReal->nBlob-pReal->nJournal) ){ 452 rc = SQLITE_FULL; 453 }else{ 454 rc = pF->pMethods->xWrite(pF, zBuf, iAmt, iOfst+BLOCKSIZE); 455 if( rc==SQLITE_OK ){ 456 pReal->nDatabase = MAX(pReal->nDatabase, iAmt+iOfst); 457 } 458 } 459 }else{ 460 /* Journal file. */ 461 int iRem = iAmt; 462 int iBuf = 0; 463 int ii = iOfst; 464 while( iRem>0 && rc==SQLITE_OK ){ 465 int iRealOff = pReal->nBlob - BLOCKSIZE*((ii/BLOCKSIZE)+1) + ii%BLOCKSIZE; 466 int iRealAmt = MIN(iRem, BLOCKSIZE - (iRealOff%BLOCKSIZE)); 467 468 if( iRealOff<(pReal->nDatabase+BLOCKSIZE) ){ 469 rc = SQLITE_FULL; 470 }else{ 471 rc = pF->pMethods->xWrite(pF, &((char *)zBuf)[iBuf], iRealAmt,iRealOff); 472 ii += iRealAmt; 473 iBuf += iRealAmt; 474 iRem -= iRealAmt; 475 } 476 } 477 if( rc==SQLITE_OK ){ 478 pReal->nJournal = MAX(pReal->nJournal, iAmt+iOfst); 479 } 480 } 481 482 return rc; 483} 484 485/* 486** Truncate an fs-file. 487*/ 488static int fsTruncate(sqlite3_file *pFile, sqlite_int64 size){ 489 fs_file *p = (fs_file *)pFile; 490 fs_real_file *pReal = p->pReal; 491 if( p->eType==DATABASE_FILE ){ 492 pReal->nDatabase = MIN(pReal->nDatabase, size); 493 }else{ 494 pReal->nJournal = MIN(pReal->nJournal, size); 495 } 496 return SQLITE_OK; 497} 498 499/* 500** Sync an fs-file. 501*/ 502static int fsSync(sqlite3_file *pFile, int flags){ 503 fs_file *p = (fs_file *)pFile; 504 fs_real_file *pReal = p->pReal; 505 sqlite3_file *pRealFile = pReal->pFile; 506 int rc = SQLITE_OK; 507 508 if( p->eType==DATABASE_FILE ){ 509 unsigned char zSize[4]; 510 zSize[0] = (pReal->nDatabase&0xFF000000)>>24; 511 zSize[1] = (pReal->nDatabase&0x00FF0000)>>16; 512 zSize[2] = (pReal->nDatabase&0x0000FF00)>>8; 513 zSize[3] = (pReal->nDatabase&0x000000FF); 514 rc = pRealFile->pMethods->xWrite(pRealFile, zSize, 4, 0); 515 } 516 if( rc==SQLITE_OK ){ 517 rc = pRealFile->pMethods->xSync(pRealFile, flags&(~SQLITE_SYNC_DATAONLY)); 518 } 519 520 return rc; 521} 522 523/* 524** Return the current file-size of an fs-file. 525*/ 526static int fsFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){ 527 fs_file *p = (fs_file *)pFile; 528 fs_real_file *pReal = p->pReal; 529 if( p->eType==DATABASE_FILE ){ 530 *pSize = pReal->nDatabase; 531 }else{ 532 *pSize = pReal->nJournal; 533 } 534 return SQLITE_OK; 535} 536 537/* 538** Lock an fs-file. 539*/ 540static int fsLock(sqlite3_file *pFile, int eLock){ 541 return SQLITE_OK; 542} 543 544/* 545** Unlock an fs-file. 546*/ 547static int fsUnlock(sqlite3_file *pFile, int eLock){ 548 return SQLITE_OK; 549} 550 551/* 552** Check if another file-handle holds a RESERVED lock on an fs-file. 553*/ 554static int fsCheckReservedLock(sqlite3_file *pFile, int *pResOut){ 555 *pResOut = 0; 556 return SQLITE_OK; 557} 558 559/* 560** File control method. For custom operations on an fs-file. 561*/ 562static int fsFileControl(sqlite3_file *pFile, int op, void *pArg){ 563 return SQLITE_OK; 564} 565 566/* 567** Return the sector-size in bytes for an fs-file. 568*/ 569static int fsSectorSize(sqlite3_file *pFile){ 570 return BLOCKSIZE; 571} 572 573/* 574** Return the device characteristic flags supported by an fs-file. 575*/ 576static int fsDeviceCharacteristics(sqlite3_file *pFile){ 577 return 0; 578} 579 580/* 581** Open an fs file handle. 582*/ 583static int fsOpen( 584 sqlite3_vfs *pVfs, 585 const char *zName, 586 sqlite3_file *pFile, 587 int flags, 588 int *pOutFlags 589){ 590 fs_vfs_t *pFsVfs = (fs_vfs_t *)pVfs; 591 fs_file *p = (fs_file *)pFile; 592 fs_real_file *pReal = 0; 593 int eType; 594 int nName; 595 int rc = SQLITE_OK; 596 597 if( 0==(flags&(SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_MAIN_JOURNAL)) ){ 598 tmp_file *p = (tmp_file *)pFile; 599 memset(p, 0, sizeof(*p)); 600 p->base.pMethods = &tmp_io_methods; 601 return SQLITE_OK; 602 } 603 604 eType = ((flags&(SQLITE_OPEN_MAIN_DB))?DATABASE_FILE:JOURNAL_FILE); 605 p->base.pMethods = &fs_io_methods; 606 p->eType = eType; 607 608 assert(strlen("-journal")==8); 609 nName = strlen(zName)-((eType==JOURNAL_FILE)?8:0); 610 pReal=pFsVfs->pFileList; 611 for(; pReal && strncmp(pReal->zName, zName, nName); pReal=pReal->pNext); 612 613 if( !pReal ){ 614 int real_flags = (flags&~(SQLITE_OPEN_MAIN_DB))|SQLITE_OPEN_TEMP_DB; 615 sqlite3_int64 size; 616 sqlite3_file *pRealFile; 617 sqlite3_vfs *pParent = pFsVfs->pParent; 618 assert(eType==DATABASE_FILE); 619 620 pReal = (fs_real_file *)sqlite3_malloc(sizeof(*pReal)+pParent->szOsFile); 621 if( !pReal ){ 622 rc = SQLITE_NOMEM; 623 goto open_out; 624 } 625 memset(pReal, 0, sizeof(*pReal)+pParent->szOsFile); 626 pReal->zName = zName; 627 pReal->pFile = (sqlite3_file *)(&pReal[1]); 628 629 rc = pParent->xOpen(pParent, zName, pReal->pFile, real_flags, pOutFlags); 630 if( rc!=SQLITE_OK ){ 631 goto open_out; 632 } 633 pRealFile = pReal->pFile; 634 635 rc = pRealFile->pMethods->xFileSize(pRealFile, &size); 636 if( rc!=SQLITE_OK ){ 637 goto open_out; 638 } 639 if( size==0 ){ 640 rc = pRealFile->pMethods->xWrite(pRealFile, "\0", 1, BLOBSIZE-1); 641 pReal->nBlob = BLOBSIZE; 642 }else{ 643 unsigned char zS[4]; 644 pReal->nBlob = size; 645 rc = pRealFile->pMethods->xRead(pRealFile, zS, 4, 0); 646 pReal->nDatabase = (zS[0]<<24)+(zS[1]<<16)+(zS[2]<<8)+zS[3]; 647 if( rc==SQLITE_OK ){ 648 rc = pRealFile->pMethods->xRead(pRealFile, zS, 4, pReal->nBlob-4); 649 if( zS[0] || zS[1] || zS[2] || zS[3] ){ 650 pReal->nJournal = pReal->nBlob; 651 } 652 } 653 } 654 655 if( rc==SQLITE_OK ){ 656 pReal->pNext = pFsVfs->pFileList; 657 if( pReal->pNext ){ 658 pReal->pNext->ppThis = &pReal->pNext; 659 } 660 pReal->ppThis = &pFsVfs->pFileList; 661 pFsVfs->pFileList = pReal; 662 } 663 } 664 665open_out: 666 if( pReal ){ 667 if( rc==SQLITE_OK ){ 668 p->pReal = pReal; 669 pReal->nRef++; 670 }else{ 671 if( pReal->pFile->pMethods ){ 672 pReal->pFile->pMethods->xClose(pReal->pFile); 673 } 674 sqlite3_free(pReal); 675 } 676 } 677 return rc; 678} 679 680/* 681** Delete the file located at zPath. If the dirSync argument is true, 682** ensure the file-system modifications are synced to disk before 683** returning. 684*/ 685static int fsDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){ 686 int rc = SQLITE_OK; 687 fs_vfs_t *pFsVfs = (fs_vfs_t *)pVfs; 688 fs_real_file *pReal; 689 sqlite3_file *pF; 690 int nName = strlen(zPath) - 8; 691 692 assert(strlen("-journal")==8); 693 assert(strcmp("-journal", &zPath[nName])==0); 694 695 pReal = pFsVfs->pFileList; 696 for(; pReal && strncmp(pReal->zName, zPath, nName); pReal=pReal->pNext); 697 if( pReal ){ 698 pF = pReal->pFile; 699 rc = pF->pMethods->xWrite(pF, "\0\0\0\0", 4, pReal->nBlob-BLOCKSIZE); 700 if( rc==SQLITE_OK ){ 701 pReal->nJournal = 0; 702 } 703 } 704 return rc; 705} 706 707/* 708** Test for access permissions. Return true if the requested permission 709** is available, or false otherwise. 710*/ 711static int fsAccess( 712 sqlite3_vfs *pVfs, 713 const char *zPath, 714 int flags, 715 int *pResOut 716){ 717 fs_vfs_t *pFsVfs = (fs_vfs_t *)pVfs; 718 fs_real_file *pReal; 719 int isJournal = 0; 720 int nName = strlen(zPath); 721 722 if( flags!=SQLITE_ACCESS_EXISTS ){ 723 sqlite3_vfs *pParent = ((fs_vfs_t *)pVfs)->pParent; 724 return pParent->xAccess(pParent, zPath, flags, pResOut); 725 } 726 727 assert(strlen("-journal")==8); 728 if( nName>8 && strcmp("-journal", &zPath[nName-8])==0 ){ 729 nName -= 8; 730 isJournal = 1; 731 } 732 733 pReal = pFsVfs->pFileList; 734 for(; pReal && strncmp(pReal->zName, zPath, nName); pReal=pReal->pNext); 735 736 *pResOut = (pReal && (!isJournal || pReal->nJournal>0)); 737 return SQLITE_OK; 738} 739 740/* 741** Populate buffer zOut with the full canonical pathname corresponding 742** to the pathname in zPath. zOut is guaranteed to point to a buffer 743** of at least (FS_MAX_PATHNAME+1) bytes. 744*/ 745static int fsFullPathname( 746 sqlite3_vfs *pVfs, /* Pointer to vfs object */ 747 const char *zPath, /* Possibly relative input path */ 748 int nOut, /* Size of output buffer in bytes */ 749 char *zOut /* Output buffer */ 750){ 751 sqlite3_vfs *pParent = ((fs_vfs_t *)pVfs)->pParent; 752 return pParent->xFullPathname(pParent, zPath, nOut, zOut); 753} 754 755/* 756** Open the dynamic library located at zPath and return a handle. 757*/ 758static void *fsDlOpen(sqlite3_vfs *pVfs, const char *zPath){ 759 sqlite3_vfs *pParent = ((fs_vfs_t *)pVfs)->pParent; 760 return pParent->xDlOpen(pParent, zPath); 761} 762 763/* 764** Populate the buffer zErrMsg (size nByte bytes) with a human readable 765** utf-8 string describing the most recent error encountered associated 766** with dynamic libraries. 767*/ 768static void fsDlError(sqlite3_vfs *pVfs, int nByte, char *zErrMsg){ 769 sqlite3_vfs *pParent = ((fs_vfs_t *)pVfs)->pParent; 770 pParent->xDlError(pParent, nByte, zErrMsg); 771} 772 773/* 774** Return a pointer to the symbol zSymbol in the dynamic library pHandle. 775*/ 776static void (*fsDlSym(sqlite3_vfs *pVfs, void *pH, const char *zSym))(void){ 777 sqlite3_vfs *pParent = ((fs_vfs_t *)pVfs)->pParent; 778 return pParent->xDlSym(pParent, pH, zSym); 779} 780 781/* 782** Close the dynamic library handle pHandle. 783*/ 784static void fsDlClose(sqlite3_vfs *pVfs, void *pHandle){ 785 sqlite3_vfs *pParent = ((fs_vfs_t *)pVfs)->pParent; 786 pParent->xDlClose(pParent, pHandle); 787} 788 789/* 790** Populate the buffer pointed to by zBufOut with nByte bytes of 791** random data. 792*/ 793static int fsRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){ 794 sqlite3_vfs *pParent = ((fs_vfs_t *)pVfs)->pParent; 795 return pParent->xRandomness(pParent, nByte, zBufOut); 796} 797 798/* 799** Sleep for nMicro microseconds. Return the number of microseconds 800** actually slept. 801*/ 802static int fsSleep(sqlite3_vfs *pVfs, int nMicro){ 803 sqlite3_vfs *pParent = ((fs_vfs_t *)pVfs)->pParent; 804 return pParent->xSleep(pParent, nMicro); 805} 806 807/* 808** Return the current time as a Julian Day number in *pTimeOut. 809*/ 810static int fsCurrentTime(sqlite3_vfs *pVfs, double *pTimeOut){ 811 sqlite3_vfs *pParent = ((fs_vfs_t *)pVfs)->pParent; 812 return pParent->xCurrentTime(pParent, pTimeOut); 813} 814 815/* 816** This procedure registers the fs vfs with SQLite. If the argument is 817** true, the fs vfs becomes the new default vfs. It is the only publicly 818** available function in this file. 819*/ 820int fs_register(void){ 821 if( fs_vfs.pParent ) return SQLITE_OK; 822 fs_vfs.pParent = sqlite3_vfs_find(0); 823 fs_vfs.base.mxPathname = fs_vfs.pParent->mxPathname; 824 fs_vfs.base.szOsFile = MAX(sizeof(tmp_file), sizeof(fs_file)); 825 return sqlite3_vfs_register(&fs_vfs.base, 0); 826} 827 828#ifdef SQLITE_TEST 829 int SqlitetestOnefile_Init() {return fs_register();} 830#endif 831