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Diffstat (limited to 'ext/misc/cksumvfs.c')
| -rw-r--r-- | ext/misc/cksumvfs.c | 880 |
1 files changed, 880 insertions, 0 deletions
diff --git a/ext/misc/cksumvfs.c b/ext/misc/cksumvfs.c new file mode 100644 index 0000000..e7c2c9d --- /dev/null +++ b/ext/misc/cksumvfs.c @@ -0,0 +1,880 @@ +/* +** 2020-04-20 +** +** The author disclaims copyright to this source code. In place of +** a legal notice, here is a blessing: +** +** May you do good and not evil. +** May you find forgiveness for yourself and forgive others. +** May you share freely, never taking more than you give. +** +****************************************************************************** +** +** This file implements a VFS shim that writes a checksum on each page +** of an SQLite database file. When reading pages, the checksum is verified +** and an error is raised if the checksum is incorrect. +** +** COMPILING +** +** This extension requires SQLite 3.32.0 or later. It uses the +** sqlite3_database_file_object() interface which was added in +** version 3.32.0, so it will not link with an earlier version of +** SQLite. +** +** To build this extension as a separately loaded shared library or +** DLL, use compiler command-lines similar to the following: +** +** (linux) gcc -fPIC -shared cksumvfs.c -o cksumvfs.so +** (mac) clang -fPIC -dynamiclib cksumvfs.c -o cksumvfs.dylib +** (windows) cl cksumvfs.c -link -dll -out:cksumvfs.dll +** +** You may want to add additional compiler options, of course, +** according to the needs of your project. +** +** If you want to statically link this extension with your product, +** then compile it like any other C-language module but add the +** "-DSQLITE_CKSUMVFS_STATIC" option so that this module knows that +** it is being statically linked rather than dynamically linked +** +** LOADING +** +** To load this extension as a shared library, you first have to +** bring up a dummy SQLite database connection to use as the argument +** to the sqlite3_load_extension() API call. Then you invoke the +** sqlite3_load_extension() API and shutdown the dummy database +** connection. All subsequent database connections that are opened +** will include this extension. For example: +** +** sqlite3 *db; +** sqlite3_open(":memory:", &db); +** sqlite3_load_extension(db, "./cksumvfs"); +** sqlite3_close(db); +** +** If this extension is compiled with -DSQLITE_CKSUMVFS_STATIC and +** statically linked against the application, initialize it using +** a single API call as follows: +** +** sqlite3_register_cksumvfs(); +** +** Cksumvfs is a VFS Shim. When loaded, "cksmvfs" becomes the new +** default VFS and it uses the prior default VFS as the next VFS +** down in the stack. This is normally what you want. However, in +** complex situations where multiple VFS shims are being loaded, +** it might be important to ensure that cksumvfs is loaded in the +** correct order so that it sequences itself into the default VFS +** Shim stack in the right order. +** +** USING +** +** Open database connections using the sqlite3_open() or +** sqlite3_open_v2() interfaces, as normal. Ordinary database files +** (without a checksum) will operate normally. Databases with +** checksums will return an SQLITE_IOERR_DATA error if a page is +** encountered that contains an invalid checksum. +** +** Checksumming only works on databases that have a reserve-bytes +** value of exactly 8. The default value for reserve-bytes is 0. +** Hence, newly created database files will omit the checksum by +** default. To create a database that includes a checksum, change +** the reserve-bytes value to 8 by runing: +** +** int n = 8; +** sqlite3_file_control(db, 0, SQLITE_FCNTL_RESERVE_BYTES, &n); +** +** If you do this immediately after creating a new database file, +** before anything else has been written into the file, then that +** might be all that you need to do. Otherwise, the API call +** above should be followed by: +** +** sqlite3_exec(db, "VACUUM", 0, 0, 0); +** +** It never hurts to run the VACUUM, even if you don't need it. +** If the database is in WAL mode, you should shutdown and +** reopen all database connections before continuing. +** +** From the CLI, use the ".filectrl reserve_bytes 8" command, +** followed by "VACUUM;". +** +** Note that SQLite allows the number of reserve-bytes to be +** increased but not decreased. So if a database file already +** has a reserve-bytes value greater than 8, there is no way to +** activate checksumming on that database, other than to dump +** and restore the database file. Note also that other extensions +** might also make use of the reserve-bytes. Checksumming will +** be incompatible with those other extensions. +** +** VERIFICATION OF CHECKSUMS +** +** If any checksum is incorrect, the "PRAGMA quick_check" command +** will find it. To verify that checksums are actually enabled +** and running, use the following query: +** +** SELECT count(*), verify_checksum(data) +** FROM sqlite_dbpage +** GROUP BY 2; +** +** There are three possible outputs form the verify_checksum() +** function: 1, 0, and NULL. 1 is returned if the checksum is +** correct. 0 is returned if the checksum is incorrect. NULL +** is returned if the page is unreadable. If checksumming is +** enabled, the read will fail if the checksum is wrong, so the +** usual result from verify_checksum() on a bad checksum is NULL. +** +** If everything is OK, the query above should return a single +** row where the second column is 1. Any other result indicates +** either that there is a checksum error, or checksum validation +** is disabled. +** +** CONTROLLING CHECKSUM VERIFICATION +** +** The cksumvfs extension implements a new PRAGMA statement that can +** be used to disable, re-enable, or query the status of checksum +** verification: +** +** PRAGMA checksum_verification; -- query status +** PRAGMA checksum_verification=OFF; -- disable verification +** PRAGMA checksum_verification=ON; -- re-enable verification +** +** The "checksum_verification" pragma will return "1" (true) or "0" +** (false) if checksum verification is enabled or disabled, respectively. +** "Verification" in this context means the feature that causes +** SQLITE_IOERR_DATA errors if a checksum mismatch is detected while +** reading. Checksums are always kept up-to-date as long as the +** reserve-bytes value of the database is 8, regardless of the setting +** of this pragma. Checksum verification can be disabled (for example) +** to do forensic analysis of a database that has previously reported +** a checksum error. +** +** The "checksum_verification" pragma will always respond with "0" if +** the database file does not have a reserve-bytes value of 8. The +** pragma will return no rows at all if the cksumvfs extension is +** not loaded. +** +** IMPLEMENTATION NOTES +** +** The checksum is stored in the last 8 bytes of each page. This +** module only operates if the "bytes of reserved space on each page" +** value at offset 20 the SQLite database header is exactly 8. If +** the reserved-space value is not 8, this module is a no-op. +*/ +#if defined(SQLITE_AMALGAMATION) && !defined(SQLITE_CKSUMVFS_STATIC) +# define SQLITE_CKSUMVFS_STATIC +#endif +#ifdef SQLITE_CKSUMVFS_STATIC +# include "sqlite3.h" +#else +# include "sqlite3ext.h" + SQLITE_EXTENSION_INIT1 +#endif +#include <string.h> +#include <assert.h> + + +/* +** Forward declaration of objects used by this utility +*/ +typedef struct sqlite3_vfs CksmVfs; +typedef struct CksmFile CksmFile; + +/* +** Useful datatype abbreviations +*/ +#if !defined(SQLITE_AMALGAMATION) + typedef unsigned char u8; + typedef unsigned int u32; +#endif + +/* Access to a lower-level VFS that (might) implement dynamic loading, +** access to randomness, etc. +*/ +#define ORIGVFS(p) ((sqlite3_vfs*)((p)->pAppData)) +#define ORIGFILE(p) ((sqlite3_file*)(((CksmFile*)(p))+1)) + +/* An open file */ +struct CksmFile { + sqlite3_file base; /* IO methods */ + const char *zFName; /* Original name of the file */ + char computeCksm; /* True to compute checksums. + ** Always true if reserve size is 8. */ + char verifyCksm; /* True to verify checksums */ + char isWal; /* True if processing a WAL file */ + char inCkpt; /* Currently doing a checkpoint */ + CksmFile *pPartner; /* Ptr from WAL to main-db, or from main-db to WAL */ +}; + +/* +** Methods for CksmFile +*/ +static int cksmClose(sqlite3_file*); +static int cksmRead(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst); +static int cksmWrite(sqlite3_file*,const void*,int iAmt, sqlite3_int64 iOfst); +static int cksmTruncate(sqlite3_file*, sqlite3_int64 size); +static int cksmSync(sqlite3_file*, int flags); +static int cksmFileSize(sqlite3_file*, sqlite3_int64 *pSize); +static int cksmLock(sqlite3_file*, int); +static int cksmUnlock(sqlite3_file*, int); +static int cksmCheckReservedLock(sqlite3_file*, int *pResOut); +static int cksmFileControl(sqlite3_file*, int op, void *pArg); +static int cksmSectorSize(sqlite3_file*); +static int cksmDeviceCharacteristics(sqlite3_file*); +static int cksmShmMap(sqlite3_file*, int iPg, int pgsz, int, void volatile**); +static int cksmShmLock(sqlite3_file*, int offset, int n, int flags); +static void cksmShmBarrier(sqlite3_file*); +static int cksmShmUnmap(sqlite3_file*, int deleteFlag); +static int cksmFetch(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp); +static int cksmUnfetch(sqlite3_file*, sqlite3_int64 iOfst, void *p); + +/* +** Methods for CksmVfs +*/ +static int cksmOpen(sqlite3_vfs*, const char *, sqlite3_file*, int , int *); +static int cksmDelete(sqlite3_vfs*, const char *zName, int syncDir); +static int cksmAccess(sqlite3_vfs*, const char *zName, int flags, int *); +static int cksmFullPathname(sqlite3_vfs*, const char *zName, int, char *zOut); +static void *cksmDlOpen(sqlite3_vfs*, const char *zFilename); +static void cksmDlError(sqlite3_vfs*, int nByte, char *zErrMsg); +static void (*cksmDlSym(sqlite3_vfs *pVfs, void *p, const char*zSym))(void); +static void cksmDlClose(sqlite3_vfs*, void*); +static int cksmRandomness(sqlite3_vfs*, int nByte, char *zOut); +static int cksmSleep(sqlite3_vfs*, int microseconds); +static int cksmCurrentTime(sqlite3_vfs*, double*); +static int cksmGetLastError(sqlite3_vfs*, int, char *); +static int cksmCurrentTimeInt64(sqlite3_vfs*, sqlite3_int64*); +static int cksmSetSystemCall(sqlite3_vfs*, const char*,sqlite3_syscall_ptr); +static sqlite3_syscall_ptr cksmGetSystemCall(sqlite3_vfs*, const char *z); +static const char *cksmNextSystemCall(sqlite3_vfs*, const char *zName); + +static sqlite3_vfs cksm_vfs = { + 3, /* iVersion (set when registered) */ + 0, /* szOsFile (set when registered) */ + 1024, /* mxPathname */ + 0, /* pNext */ + "cksmvfs", /* zName */ + 0, /* pAppData (set when registered) */ + cksmOpen, /* xOpen */ + cksmDelete, /* xDelete */ + cksmAccess, /* xAccess */ + cksmFullPathname, /* xFullPathname */ + cksmDlOpen, /* xDlOpen */ + cksmDlError, /* xDlError */ + cksmDlSym, /* xDlSym */ + cksmDlClose, /* xDlClose */ + cksmRandomness, /* xRandomness */ + cksmSleep, /* xSleep */ + cksmCurrentTime, /* xCurrentTime */ + cksmGetLastError, /* xGetLastError */ + cksmCurrentTimeInt64, /* xCurrentTimeInt64 */ + cksmSetSystemCall, /* xSetSystemCall */ + cksmGetSystemCall, /* xGetSystemCall */ + cksmNextSystemCall /* xNextSystemCall */ +}; + +static const sqlite3_io_methods cksm_io_methods = { + 3, /* iVersion */ + cksmClose, /* xClose */ + cksmRead, /* xRead */ + cksmWrite, /* xWrite */ + cksmTruncate, /* xTruncate */ + cksmSync, /* xSync */ + cksmFileSize, /* xFileSize */ + cksmLock, /* xLock */ + cksmUnlock, /* xUnlock */ + cksmCheckReservedLock, /* xCheckReservedLock */ + cksmFileControl, /* xFileControl */ + cksmSectorSize, /* xSectorSize */ + cksmDeviceCharacteristics, /* xDeviceCharacteristics */ + cksmShmMap, /* xShmMap */ + cksmShmLock, /* xShmLock */ + cksmShmBarrier, /* xShmBarrier */ + cksmShmUnmap, /* xShmUnmap */ + cksmFetch, /* xFetch */ + cksmUnfetch /* xUnfetch */ +}; + +/* Do byte swapping on a unsigned 32-bit integer */ +#define BYTESWAP32(x) ( \ + (((x)&0x000000FF)<<24) + (((x)&0x0000FF00)<<8) \ + + (((x)&0x00FF0000)>>8) + (((x)&0xFF000000)>>24) \ +) + +/* Compute a checksum on a buffer */ +static void cksmCompute( + u8 *a, /* Content to be checksummed */ + int nByte, /* Bytes of content in a[]. Must be a multiple of 8. */ + u8 *aOut /* OUT: Final 8-byte checksum value output */ +){ + u32 s1 = 0, s2 = 0; + u32 *aData = (u32*)a; + u32 *aEnd = (u32*)&a[nByte]; + u32 x = 1; + + assert( nByte>=8 ); + assert( (nByte&0x00000007)==0 ); + assert( nByte<=65536 ); + + if( 1 == *(u8*)&x ){ + /* Little-endian */ + do { + s1 += *aData++ + s2; + s2 += *aData++ + s1; + }while( aData<aEnd ); + }else{ + /* Big-endian */ + do { + s1 += BYTESWAP32(aData[0]) + s2; + s2 += BYTESWAP32(aData[1]) + s1; + aData += 2; + }while( aData<aEnd ); + s1 = BYTESWAP32(s1); + s2 = BYTESWAP32(s2); + } + memcpy(aOut, &s1, 4); + memcpy(aOut+4, &s2, 4); +} + +/* +** SQL function: verify_checksum(BLOB) +** +** Return 0 or 1 if the checksum is invalid or valid. Or return +** NULL if the input is not a BLOB that is the right size for a +** database page. +*/ +static void cksmVerifyFunc( + sqlite3_context *context, + int argc, + sqlite3_value **argv +){ + int nByte; + u8 *data; + u8 cksum[8]; + data = (u8*)sqlite3_value_blob(argv[0]); + if( data==0 ) return; + if( sqlite3_value_type(argv[0])!=SQLITE_BLOB ) return; + nByte = sqlite3_value_bytes(argv[0]); + if( nByte<512 || nByte>65536 || (nByte & (nByte-1))!=0 ) return; + cksmCompute(data, nByte-8, cksum); + sqlite3_result_int(context, memcmp(data+nByte-8,cksum,8)==0); +} + +#ifdef SQLITE_CKSUMVFS_INIT_FUNCNAME +/* +** SQL function: initialize_cksumvfs(SCHEMANAME) +** +** This SQL functions (whose name is actually determined at compile-time +** by the value of the SQLITE_CKSUMVFS_INIT_FUNCNAME macro) invokes: +** +** sqlite3_file_control(db, SCHEMANAME, SQLITE_FCNTL_RESERVE_BYTE, &n); +** +** In order to set the reserve bytes value to 8, so that cksumvfs will +** operation. This feature is provided (if and only if the +** SQLITE_CKSUMVFS_INIT_FUNCNAME compile-time option is set to a string +** which is the name of the SQL function) so as to provide the ability +** to invoke the file-control in programming languages that lack +** direct access to the sqlite3_file_control() interface (ex: Java). +** +** This interface is undocumented, apart from this comment. Usage +** example: +** +** 1. Compile with -DSQLITE_CKSUMVFS_INIT_FUNCNAME="ckvfs_init" +** 2. Run: "SELECT cksum_init('main'); VACUUM;" +*/ +static void cksmInitFunc( + sqlite3_context *context, + int argc, + sqlite3_value **argv +){ + int nByte = 8; + const char *zSchemaName = (const char*)sqlite3_value_text(argv[0]); + sqlite3 *db = sqlite3_context_db_handle(context); + sqlite3_file_control(db, zSchemaName, SQLITE_FCNTL_RESERVE_BYTES, &nByte); + /* Return NULL */ +} +#endif /* SQLITE_CKSUMBFS_INIT_FUNCNAME */ + +/* +** Close a cksm-file. +*/ +static int cksmClose(sqlite3_file *pFile){ + CksmFile *p = (CksmFile *)pFile; + if( p->pPartner ){ + assert( p->pPartner->pPartner==p ); + p->pPartner->pPartner = 0; + p->pPartner = 0; + } + pFile = ORIGFILE(pFile); + return pFile->pMethods->xClose(pFile); +} + +/* +** Set the computeCkSm and verifyCksm flags, if they need to be +** changed. +*/ +static void cksmSetFlags(CksmFile *p, int hasCorrectReserveSize){ + if( hasCorrectReserveSize!=p->computeCksm ){ + p->computeCksm = p->verifyCksm = hasCorrectReserveSize; + if( p->pPartner ){ + p->pPartner->verifyCksm = hasCorrectReserveSize; + p->pPartner->computeCksm = hasCorrectReserveSize; + } + } +} + +/* +** Read data from a cksm-file. +*/ +static int cksmRead( + sqlite3_file *pFile, + void *zBuf, + int iAmt, + sqlite_int64 iOfst +){ + int rc; + CksmFile *p = (CksmFile *)pFile; + pFile = ORIGFILE(pFile); + rc = pFile->pMethods->xRead(pFile, zBuf, iAmt, iOfst); + if( rc==SQLITE_OK ){ + if( iOfst==0 && iAmt>=100 && ( + memcmp(zBuf,"SQLite format 3",16)==0 || memcmp(zBuf,"ZV-",3)==0 + )){ + u8 *d = (u8*)zBuf; + char hasCorrectReserveSize = (d[20]==8); + cksmSetFlags(p, hasCorrectReserveSize); + } + /* Verify the checksum if + ** (1) the size indicates that we are dealing with a complete + ** database page + ** (2) checksum verification is enabled + ** (3) we are not in the middle of checkpoint + */ + if( iAmt>=512 /* (1) */ + && p->verifyCksm /* (2) */ + && !p->inCkpt /* (3) */ + ){ + u8 cksum[8]; + cksmCompute((u8*)zBuf, iAmt-8, cksum); + if( memcmp((u8*)zBuf+iAmt-8, cksum, 8)!=0 ){ + sqlite3_log(SQLITE_IOERR_DATA, + "checksum fault offset %lld of \"%s\"", + iOfst, p->zFName); + rc = SQLITE_IOERR_DATA; + } + } + } + return rc; +} + +/* +** Write data to a cksm-file. +*/ +static int cksmWrite( + sqlite3_file *pFile, + const void *zBuf, + int iAmt, + sqlite_int64 iOfst +){ + CksmFile *p = (CksmFile *)pFile; + pFile = ORIGFILE(pFile); + if( iOfst==0 && iAmt>=100 && ( + memcmp(zBuf,"SQLite format 3",16)==0 || memcmp(zBuf,"ZV-",3)==0 + )){ + u8 *d = (u8*)zBuf; + char hasCorrectReserveSize = (d[20]==8); + cksmSetFlags(p, hasCorrectReserveSize); + } + /* If the write size is appropriate for a database page and if + ** checksums where ever enabled, then it will be safe to compute + ** the checksums. The reserve byte size might have increased, but + ** it will never decrease. And because it cannot decrease, the + ** checksum will not overwrite anything. + */ + if( iAmt>=512 + && p->computeCksm + && !p->inCkpt + ){ + cksmCompute((u8*)zBuf, iAmt-8, ((u8*)zBuf)+iAmt-8); + } + return pFile->pMethods->xWrite(pFile, zBuf, iAmt, iOfst); +} + +/* +** Truncate a cksm-file. +*/ +static int cksmTruncate(sqlite3_file *pFile, sqlite_int64 size){ + pFile = ORIGFILE(pFile); + return pFile->pMethods->xTruncate(pFile, size); +} + +/* +** Sync a cksm-file. +*/ +static int cksmSync(sqlite3_file *pFile, int flags){ + pFile = ORIGFILE(pFile); + return pFile->pMethods->xSync(pFile, flags); +} + +/* +** Return the current file-size of a cksm-file. +*/ +static int cksmFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){ + CksmFile *p = (CksmFile *)pFile; + pFile = ORIGFILE(p); + return pFile->pMethods->xFileSize(pFile, pSize); +} + +/* +** Lock a cksm-file. +*/ +static int cksmLock(sqlite3_file *pFile, int eLock){ + pFile = ORIGFILE(pFile); + return pFile->pMethods->xLock(pFile, eLock); +} + +/* +** Unlock a cksm-file. +*/ +static int cksmUnlock(sqlite3_file *pFile, int eLock){ + pFile = ORIGFILE(pFile); + return pFile->pMethods->xUnlock(pFile, eLock); +} + +/* +** Check if another file-handle holds a RESERVED lock on a cksm-file. +*/ +static int cksmCheckReservedLock(sqlite3_file *pFile, int *pResOut){ + pFile = ORIGFILE(pFile); + return pFile->pMethods->xCheckReservedLock(pFile, pResOut); +} + +/* +** File control method. For custom operations on a cksm-file. +*/ +static int cksmFileControl(sqlite3_file *pFile, int op, void *pArg){ + int rc; + CksmFile *p = (CksmFile*)pFile; + pFile = ORIGFILE(pFile); + if( op==SQLITE_FCNTL_PRAGMA ){ + char **azArg = (char**)pArg; + assert( azArg[1]!=0 ); + if( sqlite3_stricmp(azArg[1],"checksum_verification")==0 ){ + char *zArg = azArg[2]; + if( zArg!=0 ){ + if( (zArg[0]>='1' && zArg[0]<='9') + || sqlite3_strlike("enable%",zArg,0)==0 + || sqlite3_stricmp("yes",zArg)==0 + || sqlite3_stricmp("on",zArg)==0 + ){ + p->verifyCksm = p->computeCksm; + }else{ + p->verifyCksm = 0; + } + if( p->pPartner ) p->pPartner->verifyCksm = p->verifyCksm; + } + azArg[0] = sqlite3_mprintf("%d",p->verifyCksm); + return SQLITE_OK; + }else if( p->computeCksm && azArg[2]!=0 + && sqlite3_stricmp(azArg[1], "page_size")==0 ){ + /* Do not allow page size changes on a checksum database */ + return SQLITE_OK; + } + }else if( op==SQLITE_FCNTL_CKPT_START || op==SQLITE_FCNTL_CKPT_DONE ){ + p->inCkpt = op==SQLITE_FCNTL_CKPT_START; + if( p->pPartner ) p->pPartner->inCkpt = p->inCkpt; + }else if( op==SQLITE_FCNTL_CKSM_FILE ){ + /* This VFS needs to obtain a pointer to the corresponding database + ** file handle from within xOpen() calls to open wal files. To do this, + ** it uses the sqlite3_database_file_object() API to obtain a pointer + ** to the file-handle used by SQLite to access the db file. This is + ** fine if cksmvfs happens to be the top-level VFS, but not if there + ** are one or more wrapper VFS. To handle this case, this file-control + ** is used to extract the cksmvfs file-handle from any wrapper file + ** handle. */ + sqlite3_file **ppFile = (sqlite3_file**)pArg; + *ppFile = (sqlite3_file*)p; + return SQLITE_OK; + } + rc = pFile->pMethods->xFileControl(pFile, op, pArg); + if( rc==SQLITE_OK && op==SQLITE_FCNTL_VFSNAME ){ + *(char**)pArg = sqlite3_mprintf("cksm/%z", *(char**)pArg); + } + return rc; +} + +/* +** Return the sector-size in bytes for a cksm-file. +*/ +static int cksmSectorSize(sqlite3_file *pFile){ + pFile = ORIGFILE(pFile); + return pFile->pMethods->xSectorSize(pFile); +} + +/* +** Return the device characteristic flags supported by a cksm-file. +*/ +static int cksmDeviceCharacteristics(sqlite3_file *pFile){ + pFile = ORIGFILE(pFile); + return pFile->pMethods->xDeviceCharacteristics(pFile); +} + +/* Create a shared memory file mapping */ +static int cksmShmMap( + sqlite3_file *pFile, + int iPg, + int pgsz, + int bExtend, + void volatile **pp +){ + pFile = ORIGFILE(pFile); + return pFile->pMethods->xShmMap(pFile,iPg,pgsz,bExtend,pp); +} + +/* Perform locking on a shared-memory segment */ +static int cksmShmLock(sqlite3_file *pFile, int offset, int n, int flags){ + pFile = ORIGFILE(pFile); + return pFile->pMethods->xShmLock(pFile,offset,n,flags); +} + +/* Memory barrier operation on shared memory */ +static void cksmShmBarrier(sqlite3_file *pFile){ + pFile = ORIGFILE(pFile); + pFile->pMethods->xShmBarrier(pFile); +} + +/* Unmap a shared memory segment */ +static int cksmShmUnmap(sqlite3_file *pFile, int deleteFlag){ + pFile = ORIGFILE(pFile); + return pFile->pMethods->xShmUnmap(pFile,deleteFlag); +} + +/* Fetch a page of a memory-mapped file */ +static int cksmFetch( + sqlite3_file *pFile, + sqlite3_int64 iOfst, + int iAmt, + void **pp +){ + CksmFile *p = (CksmFile *)pFile; + if( p->computeCksm ){ + *pp = 0; + return SQLITE_OK; + } + pFile = ORIGFILE(pFile); + if( pFile->pMethods->iVersion>2 && pFile->pMethods->xFetch ){ + return pFile->pMethods->xFetch(pFile, iOfst, iAmt, pp); + } + *pp = 0; + return SQLITE_OK; +} + +/* Release a memory-mapped page */ +static int cksmUnfetch(sqlite3_file *pFile, sqlite3_int64 iOfst, void *pPage){ + pFile = ORIGFILE(pFile); + if( pFile->pMethods->iVersion>2 && pFile->pMethods->xUnfetch ){ + return pFile->pMethods->xUnfetch(pFile, iOfst, pPage); + } + return SQLITE_OK; +} + +/* +** Open a cksm file handle. +*/ +static int cksmOpen( + sqlite3_vfs *pVfs, + const char *zName, + sqlite3_file *pFile, + int flags, + int *pOutFlags +){ + CksmFile *p; + sqlite3_file *pSubFile; + sqlite3_vfs *pSubVfs; + int rc; + pSubVfs = ORIGVFS(pVfs); + if( (flags & (SQLITE_OPEN_MAIN_DB|SQLITE_OPEN_WAL))==0 ){ + return pSubVfs->xOpen(pSubVfs, zName, pFile, flags, pOutFlags); + } + p = (CksmFile*)pFile; + memset(p, 0, sizeof(*p)); + pSubFile = ORIGFILE(pFile); + pFile->pMethods = &cksm_io_methods; + rc = pSubVfs->xOpen(pSubVfs, zName, pSubFile, flags, pOutFlags); + if( rc ) goto cksm_open_done; + if( flags & SQLITE_OPEN_WAL ){ + sqlite3_file *pDb = sqlite3_database_file_object(zName); + rc = pDb->pMethods->xFileControl(pDb, SQLITE_FCNTL_CKSM_FILE, (void*)&pDb); + assert( rc==SQLITE_OK ); + p->pPartner = (CksmFile*)pDb; + assert( p->pPartner->pPartner==0 ); + p->pPartner->pPartner = p; + p->isWal = 1; + p->computeCksm = p->pPartner->computeCksm; + }else{ + p->isWal = 0; + p->computeCksm = 0; + } + p->zFName = zName; +cksm_open_done: + if( rc ) pFile->pMethods = 0; + return rc; +} + +/* +** All other VFS methods are pass-thrus. +*/ +static int cksmDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){ + return ORIGVFS(pVfs)->xDelete(ORIGVFS(pVfs), zPath, dirSync); +} +static int cksmAccess( + sqlite3_vfs *pVfs, + const char *zPath, + int flags, + int *pResOut +){ + return ORIGVFS(pVfs)->xAccess(ORIGVFS(pVfs), zPath, flags, pResOut); +} +static int cksmFullPathname( + sqlite3_vfs *pVfs, + const char *zPath, + int nOut, + char *zOut +){ + return ORIGVFS(pVfs)->xFullPathname(ORIGVFS(pVfs),zPath,nOut,zOut); +} +static void *cksmDlOpen(sqlite3_vfs *pVfs, const char *zPath){ + return ORIGVFS(pVfs)->xDlOpen(ORIGVFS(pVfs), zPath); +} +static void cksmDlError(sqlite3_vfs *pVfs, int nByte, char *zErrMsg){ + ORIGVFS(pVfs)->xDlError(ORIGVFS(pVfs), nByte, zErrMsg); +} +static void (*cksmDlSym(sqlite3_vfs *pVfs, void *p, const char *zSym))(void){ + return ORIGVFS(pVfs)->xDlSym(ORIGVFS(pVfs), p, zSym); +} +static void cksmDlClose(sqlite3_vfs *pVfs, void *pHandle){ + ORIGVFS(pVfs)->xDlClose(ORIGVFS(pVfs), pHandle); +} +static int cksmRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){ + return ORIGVFS(pVfs)->xRandomness(ORIGVFS(pVfs), nByte, zBufOut); +} +static int cksmSleep(sqlite3_vfs *pVfs, int nMicro){ + return ORIGVFS(pVfs)->xSleep(ORIGVFS(pVfs), nMicro); +} +static int cksmCurrentTime(sqlite3_vfs *pVfs, double *pTimeOut){ + return ORIGVFS(pVfs)->xCurrentTime(ORIGVFS(pVfs), pTimeOut); +} +static int cksmGetLastError(sqlite3_vfs *pVfs, int a, char *b){ + return ORIGVFS(pVfs)->xGetLastError(ORIGVFS(pVfs), a, b); +} +static int cksmCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *p){ + sqlite3_vfs *pOrig = ORIGVFS(pVfs); + int rc; + assert( pOrig->iVersion>=2 ); + if( pOrig->xCurrentTimeInt64 ){ + rc = pOrig->xCurrentTimeInt64(pOrig, p); + }else{ + double r; + rc = pOrig->xCurrentTime(pOrig, &r); + *p = (sqlite3_int64)(r*86400000.0); + } + return rc; +} +static int cksmSetSystemCall( + sqlite3_vfs *pVfs, + const char *zName, + sqlite3_syscall_ptr pCall +){ + return ORIGVFS(pVfs)->xSetSystemCall(ORIGVFS(pVfs),zName,pCall); +} +static sqlite3_syscall_ptr cksmGetSystemCall( + sqlite3_vfs *pVfs, + const char *zName +){ + return ORIGVFS(pVfs)->xGetSystemCall(ORIGVFS(pVfs),zName); +} +static const char *cksmNextSystemCall(sqlite3_vfs *pVfs, const char *zName){ + return ORIGVFS(pVfs)->xNextSystemCall(ORIGVFS(pVfs), zName); +} + +/* Register the verify_checksum() SQL function. +*/ +static int cksmRegisterFunc( + sqlite3 *db, + char **pzErrMsg, + const sqlite3_api_routines *pApi +){ + int rc; + if( db==0 ) return SQLITE_OK; + rc = sqlite3_create_function(db, "verify_checksum", 1, + SQLITE_UTF8|SQLITE_INNOCUOUS|SQLITE_DETERMINISTIC, + 0, cksmVerifyFunc, 0, 0); +#ifdef SQLITE_CKSUMVFS_INIT_FUNCNAME + (void)sqlite3_create_function(db, SQLITE_CKSUMVFS_INIT_FUNCNAME, 1, + SQLITE_UTF8|SQLITE_DIRECTONLY, + 0, cksmInitFunc, 0, 0); +#endif + return rc; +} + +/* +** Register the cksum VFS as the default VFS for the system. +** Also make arrangements to automatically register the "verify_checksum()" +** SQL function on each new database connection. +*/ +static int cksmRegisterVfs(void){ + int rc = SQLITE_OK; + sqlite3_vfs *pOrig; + if( sqlite3_vfs_find("cksmvfs")!=0 ) return SQLITE_OK; + pOrig = sqlite3_vfs_find(0); + if( pOrig==0 ) return SQLITE_ERROR; + cksm_vfs.iVersion = pOrig->iVersion; + cksm_vfs.pAppData = pOrig; + cksm_vfs.szOsFile = pOrig->szOsFile + sizeof(CksmFile); + rc = sqlite3_vfs_register(&cksm_vfs, 1); + if( rc==SQLITE_OK ){ + rc = sqlite3_auto_extension((void(*)(void))cksmRegisterFunc); + } + return rc; +} + +#if defined(SQLITE_CKSUMVFS_STATIC) +/* This variant of the initializer runs when the extension is +** statically linked. +*/ +int sqlite3_register_cksumvfs(const char *NotUsed){ + (void)NotUsed; + return cksmRegisterVfs(); +} +int sqlite3_unregister_cksumvfs(void){ + if( sqlite3_vfs_find("cksmvfs") ){ + sqlite3_vfs_unregister(&cksm_vfs); + sqlite3_cancel_auto_extension((void(*)(void))cksmRegisterFunc); + } + return SQLITE_OK; +} +#endif /* defined(SQLITE_CKSUMVFS_STATIC */ + +#if !defined(SQLITE_CKSUMVFS_STATIC) +/* This variant of the initializer function is used when the +** extension is shared library to be loaded at run-time. +*/ +#ifdef _WIN32 +__declspec(dllexport) +#endif +/* +** This routine is called by sqlite3_load_extension() when the +** extension is first loaded. +***/ +int sqlite3_cksumvfs_init( + sqlite3 *db, + char **pzErrMsg, + const sqlite3_api_routines *pApi +){ + int rc; + SQLITE_EXTENSION_INIT2(pApi); + (void)pzErrMsg; /* not used */ + rc = cksmRegisterFunc(db, 0, 0); + if( rc==SQLITE_OK ){ + rc = cksmRegisterVfs(); + } + if( rc==SQLITE_OK ) rc = SQLITE_OK_LOAD_PERMANENTLY; + return rc; +} +#endif /* !defined(SQLITE_CKSUMVFS_STATIC) */ |