ADDED ext/misc/appendvfs.c Index: ext/misc/appendvfs.c ================================================================== --- ext/misc/appendvfs.c +++ ext/misc/appendvfs.c @@ -0,0 +1,453 @@ +/* +** 2017-10-20 +** +** 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 allows an SQLite database to be +** appended onto the end of some other file, such as an executable. +** +** A special record must appear at the end of the file that identifies the +** file as an appended database and provides an offset to page 1. For +** best performance page 1 should be located at a disk page boundary, though +** that is not required. +** +** An appended database is considered immutable. It is read-only and no +** locks are ever taken. +** +** If the file being opened is not an appended database, then this shim is +** a pass-through into the default underlying VFS. +**/ +#include +SQLITE_EXTENSION_INIT1 +#include +#include + +/* The append mark at the end of the database is: +** +** Start-Of-SQLite3-NNNNNNNN +** 123456789 123456789 12345 +** +** The NNNNNNNN represents a 64-bit big-endian unsigned integer which is +** the offset to page 1. +*/ +#define APND_MARK_PREFIX "Start-Of-SQLite3-" +#define APND_MARK_PREFIX_SZ 17 +#define APND_MARK_SIZE 25 + +/* +** Forward declaration of objects used by this utility +*/ +typedef struct sqlite3_vfs ApndVfs; +typedef struct ApndFile ApndFile; + +/* 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*)(((ApndFile*)(p))+1)) + +/* An open file */ +struct ApndFile { + sqlite3_file base; /* IO methods */ + sqlite3_int64 iPgOne; /* File offset to page 1 */ +}; + +/* +** Methods for ApndFile +*/ +static int apndClose(sqlite3_file*); +static int apndRead(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst); +static int apndWrite(sqlite3_file*,const void*,int iAmt, sqlite3_int64 iOfst); +static int apndTruncate(sqlite3_file*, sqlite3_int64 size); +static int apndSync(sqlite3_file*, int flags); +static int apndFileSize(sqlite3_file*, sqlite3_int64 *pSize); +static int apndLock(sqlite3_file*, int); +static int apndUnlock(sqlite3_file*, int); +static int apndCheckReservedLock(sqlite3_file*, int *pResOut); +static int apndFileControl(sqlite3_file*, int op, void *pArg); +static int apndSectorSize(sqlite3_file*); +static int apndDeviceCharacteristics(sqlite3_file*); +static int apndShmMap(sqlite3_file*, int iPg, int pgsz, int, void volatile**); +static int apndShmLock(sqlite3_file*, int offset, int n, int flags); +static void apndShmBarrier(sqlite3_file*); +static int apndShmUnmap(sqlite3_file*, int deleteFlag); +static int apndFetch(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp); +static int apndUnfetch(sqlite3_file*, sqlite3_int64 iOfst, void *p); + +/* +** Methods for ApndVfs +*/ +static int apndOpen(sqlite3_vfs*, const char *, sqlite3_file*, int , int *); +static int apndDelete(sqlite3_vfs*, const char *zName, int syncDir); +static int apndAccess(sqlite3_vfs*, const char *zName, int flags, int *); +static int apndFullPathname(sqlite3_vfs*, const char *zName, int, char *zOut); +static void *apndDlOpen(sqlite3_vfs*, const char *zFilename); +static void apndDlError(sqlite3_vfs*, int nByte, char *zErrMsg); +static void (*apndDlSym(sqlite3_vfs *pVfs, void *p, const char*zSym))(void); +static void apndDlClose(sqlite3_vfs*, void*); +static int apndRandomness(sqlite3_vfs*, int nByte, char *zOut); +static int apndSleep(sqlite3_vfs*, int microseconds); +static int apndCurrentTime(sqlite3_vfs*, double*); +static int apndGetLastError(sqlite3_vfs*, int, char *); +static int apndCurrentTimeInt64(sqlite3_vfs*, sqlite3_int64*); +static int apndSetSystemCall(sqlite3_vfs*, const char*,sqlite3_syscall_ptr); +static sqlite3_syscall_ptr apndGetSystemCall(sqlite3_vfs*, const char *z); +static const char *apndNextSystemCall(sqlite3_vfs*, const char *zName); + +static sqlite3_vfs apnd_vfs = { + 3, /* iVersion (set when registered) */ + 0, /* szOsFile (set when registered) */ + 1024, /* mxPathname */ + 0, /* pNext */ + "apndvfs", /* zName */ + 0, /* pAppData (set when registered) */ + apndOpen, /* xOpen */ + apndDelete, /* xDelete */ + apndAccess, /* xAccess */ + apndFullPathname, /* xFullPathname */ + apndDlOpen, /* xDlOpen */ + apndDlError, /* xDlError */ + apndDlSym, /* xDlSym */ + apndDlClose, /* xDlClose */ + apndRandomness, /* xRandomness */ + apndSleep, /* xSleep */ + apndCurrentTime, /* xCurrentTime */ + apndGetLastError, /* xGetLastError */ + apndCurrentTimeInt64, /* xCurrentTimeInt64 */ + apndSetSystemCall, /* xSetSystemCall */ + apndGetSystemCall, /* xGetSystemCall */ + apndNextSystemCall /* xNextSystemCall */ +}; + +static const sqlite3_io_methods apnd_io_methods = { + 3, /* iVersion */ + apndClose, /* xClose */ + apndRead, /* xRead */ + apndWrite, /* xWrite */ + apndTruncate, /* xTruncate */ + apndSync, /* xSync */ + apndFileSize, /* xFileSize */ + apndLock, /* xLock */ + apndUnlock, /* xUnlock */ + apndCheckReservedLock, /* xCheckReservedLock */ + apndFileControl, /* xFileControl */ + apndSectorSize, /* xSectorSize */ + apndDeviceCharacteristics, /* xDeviceCharacteristics */ + apndShmMap, /* xShmMap */ + apndShmLock, /* xShmLock */ + apndShmBarrier, /* xShmBarrier */ + apndShmUnmap, /* xShmUnmap */ + apndFetch, /* xFetch */ + apndUnfetch /* xUnfetch */ +}; + + + +/* +** Close an apnd-file. +*/ +static int apndClose(sqlite3_file *pFile){ + pFile = ORIGFILE(pFile); + return pFile->pMethods->xClose(pFile); +} + +/* +** Read data from an apnd-file. +*/ +static int apndRead( + sqlite3_file *pFile, + void *zBuf, + int iAmt, + sqlite_int64 iOfst +){ + ApndFile *p = (ApndFile *)pFile; + pFile = ORIGFILE(pFile); + return pFile->pMethods->xRead(pFile, zBuf, iAmt, iOfst+p->iPgOne); +} + +/* +** Write data to an apnd-file. +*/ +static int apndWrite( + sqlite3_file *pFile, + const void *z, + int iAmt, + sqlite_int64 iOfst +){ + return SQLITE_READONLY; +} + +/* +** Truncate an apnd-file. +*/ +static int apndTruncate(sqlite3_file *pFile, sqlite_int64 size){ + return SQLITE_READONLY; +} + +/* +** Sync an apnd-file. +*/ +static int apndSync(sqlite3_file *pFile, int flags){ + return SQLITE_READONLY; +} + +/* +** Return the current file-size of an apnd-file. +*/ +static int apndFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){ + ApndFile *p = (ApndFile*)pFile; + int rc; + pFile = ORIGFILE(p); + rc = pFile->pMethods->xFileSize(pFile, pSize); + if( rc==SQLITE_OK && p->iPgOne ){ + *pSize -= p->iPgOne + APND_MARK_SIZE; + } + return rc; +} + +/* +** Lock an apnd-file. +*/ +static int apndLock(sqlite3_file *pFile, int eLock){ + return SQLITE_READONLY; +} + +/* +** Unlock an apnd-file. +*/ +static int apndUnlock(sqlite3_file *pFile, int eLock){ + return SQLITE_OK; +} + +/* +** Check if another file-handle holds a RESERVED lock on an apnd-file. +*/ +static int apndCheckReservedLock(sqlite3_file *pFile, int *pResOut){ + *pResOut = 0; + return SQLITE_OK; +} + +/* +** File control method. For custom operations on an apnd-file. +*/ +static int apndFileControl(sqlite3_file *pFile, int op, void *pArg){ + ApndFile *p = (ApndFile *)pFile; + int rc; + pFile = ORIGFILE(pFile); + rc = pFile->pMethods->xFileControl(pFile, op, pArg); + if( rc==SQLITE_OK && op==SQLITE_FCNTL_VFSNAME ){ + *(char**)pArg = sqlite3_mprintf("apnd(%lld)/%z", p->iPgOne, *(char**)pArg); + } + return rc; +} + +/* +** Return the sector-size in bytes for an apnd-file. +*/ +static int apndSectorSize(sqlite3_file *pFile){ + pFile = ORIGFILE(pFile); + return pFile->pMethods->xSectorSize(pFile); +} + +/* +** Return the device characteristic flags supported by an apnd-file. +*/ +static int apndDeviceCharacteristics(sqlite3_file *pFile){ + pFile = ORIGFILE(pFile); + return SQLITE_IOCAP_IMMUTABLE | + pFile->pMethods->xDeviceCharacteristics(pFile); +} + +/* Create a shared memory file mapping */ +static int apndShmMap( + sqlite3_file *pFile, + int iPg, + int pgsz, + int bExtend, + void volatile **pp +){ + return SQLITE_READONLY; +} + +/* Perform locking on a shared-memory segment */ +static int apndShmLock(sqlite3_file *pFile, int offset, int n, int flags){ + return SQLITE_READONLY; +} + +/* Memory barrier operation on shared memory */ +static void apndShmBarrier(sqlite3_file *pFile){ + return; +} + +/* Unmap a shared memory segment */ +static int apndShmUnmap(sqlite3_file *pFile, int deleteFlag){ + return SQLITE_OK; +} + +/* Fetch a page of a memory-mapped file */ +static int apndFetch( + sqlite3_file *pFile, + sqlite3_int64 iOfst, + int iAmt, + void **pp +){ + ApndFile *p = (ApndFile *)pFile; + pFile = ORIGFILE(pFile); + return pFile->pMethods->xFetch(pFile, iOfst+p->iPgOne, iAmt, pp); +} + +/* Release a memory-mapped page */ +static int apndUnfetch(sqlite3_file *pFile, sqlite3_int64 iOfst, void *pPage){ + ApndFile *p = (ApndFile *)pFile; + pFile = ORIGFILE(pFile); + return pFile->pMethods->xUnfetch(pFile, iOfst+p->iPgOne, pPage); +} + +/* +** Open an apnd file handle. +*/ +static int apndOpen( + sqlite3_vfs *pVfs, + const char *zName, + sqlite3_file *pFile, + int flags, + int *pOutFlags +){ + ApndFile *p; + int rc; + sqlite3_int64 sz; + pVfs = ORIGVFS(pVfs); + if( (flags & SQLITE_OPEN_MAIN_DB)==0 ){ + return pVfs->xOpen(pVfs, zName, pFile, flags, pOutFlags); + } + p = (ApndFile*)pFile; + memset(p, 0, sizeof(*p)); + p->base.pMethods = &apnd_io_methods; + pFile = ORIGFILE(pFile); + flags &= ~(SQLITE_OPEN_CREATE|SQLITE_OPEN_READWRITE); + flags |= SQLITE_OPEN_READONLY; + rc = pVfs->xOpen(pVfs, zName, pFile, flags, pOutFlags); + if( rc ) return rc; + rc = pFile->pMethods->xFileSize(pFile, &sz); + if( rc==SQLITE_OK && sz>512 ){ + unsigned char a[APND_MARK_SIZE]; + rc = pFile->pMethods->xRead(pFile, a, APND_MARK_SIZE, sz-APND_MARK_SIZE); + if( rc==SQLITE_OK + && memcmp(a, APND_MARK_PREFIX, APND_MARK_PREFIX_SZ)==0 + ){ + p->iPgOne = + ((sqlite3_uint64)a[APND_MARK_PREFIX_SZ]<<56) + + ((sqlite3_uint64)a[APND_MARK_PREFIX_SZ+1]<<48) + + ((sqlite3_uint64)a[APND_MARK_PREFIX_SZ+2]<<40) + + ((sqlite3_uint64)a[APND_MARK_PREFIX_SZ+3]<<32) + + ((sqlite3_uint64)a[APND_MARK_PREFIX_SZ+4]<<24) + + ((sqlite3_uint64)a[APND_MARK_PREFIX_SZ+5]<<16) + + ((sqlite3_uint64)a[APND_MARK_PREFIX_SZ+6]<<8) + + ((sqlite3_uint64)a[APND_MARK_PREFIX_SZ+7]); + } + } + return SQLITE_OK; +} + +/* +** All other VFS methods are pass-thrus. +*/ +static int apndDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){ + return ORIGVFS(pVfs)->xDelete(ORIGVFS(pVfs), zPath, dirSync); +} +static int apndAccess( + sqlite3_vfs *pVfs, + const char *zPath, + int flags, + int *pResOut +){ + return ORIGVFS(pVfs)->xAccess(ORIGVFS(pVfs), zPath, flags, pResOut); +} +static int apndFullPathname( + sqlite3_vfs *pVfs, + const char *zPath, + int nOut, + char *zOut +){ + return ORIGVFS(pVfs)->xFullPathname(ORIGVFS(pVfs),zPath,nOut,zOut); +} +static void *apndDlOpen(sqlite3_vfs *pVfs, const char *zPath){ + return ORIGVFS(pVfs)->xDlOpen(ORIGVFS(pVfs), zPath); +} +static void apndDlError(sqlite3_vfs *pVfs, int nByte, char *zErrMsg){ + ORIGVFS(pVfs)->xDlError(ORIGVFS(pVfs), nByte, zErrMsg); +} +static void (*apndDlSym(sqlite3_vfs *pVfs, void *p, const char *zSym))(void){ + return ORIGVFS(pVfs)->xDlSym(ORIGVFS(pVfs), p, zSym); +} +static void apndDlClose(sqlite3_vfs *pVfs, void *pHandle){ + ORIGVFS(pVfs)->xDlClose(ORIGVFS(pVfs), pHandle); +} +static int apndRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){ + return ORIGVFS(pVfs)->xRandomness(ORIGVFS(pVfs), nByte, zBufOut); +} +static int apndSleep(sqlite3_vfs *pVfs, int nMicro){ + return ORIGVFS(pVfs)->xSleep(ORIGVFS(pVfs), nMicro); +} +static int apndCurrentTime(sqlite3_vfs *pVfs, double *pTimeOut){ + return ORIGVFS(pVfs)->xCurrentTime(ORIGVFS(pVfs), pTimeOut); +} +static int apndGetLastError(sqlite3_vfs *pVfs, int a, char *b){ + return ORIGVFS(pVfs)->xGetLastError(ORIGVFS(pVfs), a, b); +} +static int apndCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *p){ + return ORIGVFS(pVfs)->xCurrentTimeInt64(ORIGVFS(pVfs), p); +} +static int apndSetSystemCall( + sqlite3_vfs *pVfs, + const char *zName, + sqlite3_syscall_ptr pCall +){ + return ORIGVFS(pVfs)->xSetSystemCall(ORIGVFS(pVfs),zName,pCall); +} +static sqlite3_syscall_ptr apndGetSystemCall( + sqlite3_vfs *pVfs, + const char *zName +){ + return ORIGVFS(pVfs)->xGetSystemCall(ORIGVFS(pVfs),zName); +} +static const char *apndNextSystemCall(sqlite3_vfs *pVfs, const char *zName){ + return ORIGVFS(pVfs)->xNextSystemCall(ORIGVFS(pVfs), zName); +} + + +#ifdef _WIN32 +__declspec(dllexport) +#endif +/* +** This routine is called when the extension is loaded. +** Register the new VFS. +*/ +int sqlite3_appendvfs_init( + sqlite3 *db, + char **pzErrMsg, + const sqlite3_api_routines *pApi +){ + int rc = SQLITE_OK; + sqlite3_vfs *pOrig; + SQLITE_EXTENSION_INIT2(pApi); + pOrig = sqlite3_vfs_find(0); + apnd_vfs.iVersion = pOrig->iVersion; + apnd_vfs.pAppData = pOrig; + apnd_vfs.szOsFile = sizeof(ApndFile); + rc = sqlite3_vfs_register(&apnd_vfs, 1); +#ifdef APPENDVFS_TEST + if( rc==SQLITE_OK ){ + rc = sqlite3_auto_extension((void(*)(void))apndvfsRegister); + } +#endif + if( rc==SQLITE_OK ) rc = SQLITE_OK_LOAD_PERMANENTLY; + return rc; +}