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Diffstat (limited to 'ext/misc/memvfs.c')
| -rw-r--r-- | ext/misc/memvfs.c | 575 |
1 files changed, 575 insertions, 0 deletions
diff --git a/ext/misc/memvfs.c b/ext/misc/memvfs.c new file mode 100644 index 0000000..83fc946 --- /dev/null +++ b/ext/misc/memvfs.c @@ -0,0 +1,575 @@ +/* +** 2016-09-07 +** +** 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 is an in-memory VFS implementation. The application supplies +** a chunk of memory to hold the database file. +** +** Because there is place to store a rollback or wal journal, the database +** must use one of journal_mode=MEMORY or journal_mode=NONE. +** +** USAGE: +** +** sqlite3_open_v2("file:/whatever?ptr=0xf05538&sz=14336&max=65536", &db, +** SQLITE_OPEN_READWRITE | SQLITE_OPEN_URI, +** "memvfs"); +** +** These are the query parameters: +** +** ptr= The address of the memory buffer that holds the database. +** +** sz= The current size the database file +** +** maxsz= The maximum size of the database. In other words, the +** amount of space allocated for the ptr= buffer. +** +** freeonclose= If true, then sqlite3_free() is called on the ptr= +** value when the connection closes. +** +** The ptr= and sz= query parameters are required. If maxsz= is omitted, +** then it defaults to the sz= value. Parameter values can be in either +** decimal or hexadecimal. The filename in the URI is ignored. +*/ +#include <sqlite3ext.h> +SQLITE_EXTENSION_INIT1 +#include <string.h> +#include <assert.h> + + +/* +** Forward declaration of objects used by this utility +*/ +typedef struct sqlite3_vfs MemVfs; +typedef struct MemFile MemFile; + +/* Access to a lower-level VFS that (might) implement dynamic loading, +** access to randomness, etc. +*/ +#define ORIGVFS(p) ((sqlite3_vfs*)((p)->pAppData)) + +/* An open file */ +struct MemFile { + sqlite3_file base; /* IO methods */ + sqlite3_int64 sz; /* Size of the file */ + sqlite3_int64 szMax; /* Space allocated to aData */ + unsigned char *aData; /* content of the file */ + int bFreeOnClose; /* Invoke sqlite3_free() on aData at close */ +}; + +/* +** Methods for MemFile +*/ +static int memClose(sqlite3_file*); +static int memRead(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst); +static int memWrite(sqlite3_file*,const void*,int iAmt, sqlite3_int64 iOfst); +static int memTruncate(sqlite3_file*, sqlite3_int64 size); +static int memSync(sqlite3_file*, int flags); +static int memFileSize(sqlite3_file*, sqlite3_int64 *pSize); +static int memLock(sqlite3_file*, int); +static int memUnlock(sqlite3_file*, int); +static int memCheckReservedLock(sqlite3_file*, int *pResOut); +static int memFileControl(sqlite3_file*, int op, void *pArg); +static int memSectorSize(sqlite3_file*); +static int memDeviceCharacteristics(sqlite3_file*); +static int memShmMap(sqlite3_file*, int iPg, int pgsz, int, void volatile**); +static int memShmLock(sqlite3_file*, int offset, int n, int flags); +static void memShmBarrier(sqlite3_file*); +static int memShmUnmap(sqlite3_file*, int deleteFlag); +static int memFetch(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp); +static int memUnfetch(sqlite3_file*, sqlite3_int64 iOfst, void *p); + +/* +** Methods for MemVfs +*/ +static int memOpen(sqlite3_vfs*, const char *, sqlite3_file*, int , int *); +static int memDelete(sqlite3_vfs*, const char *zName, int syncDir); +static int memAccess(sqlite3_vfs*, const char *zName, int flags, int *); +static int memFullPathname(sqlite3_vfs*, const char *zName, int, char *zOut); +static void *memDlOpen(sqlite3_vfs*, const char *zFilename); +static void memDlError(sqlite3_vfs*, int nByte, char *zErrMsg); +static void (*memDlSym(sqlite3_vfs *pVfs, void *p, const char*zSym))(void); +static void memDlClose(sqlite3_vfs*, void*); +static int memRandomness(sqlite3_vfs*, int nByte, char *zOut); +static int memSleep(sqlite3_vfs*, int microseconds); +static int memCurrentTime(sqlite3_vfs*, double*); +static int memGetLastError(sqlite3_vfs*, int, char *); +static int memCurrentTimeInt64(sqlite3_vfs*, sqlite3_int64*); + +static sqlite3_vfs mem_vfs = { + 2, /* iVersion */ + 0, /* szOsFile (set when registered) */ + 1024, /* mxPathname */ + 0, /* pNext */ + "memvfs", /* zName */ + 0, /* pAppData (set when registered) */ + memOpen, /* xOpen */ + memDelete, /* xDelete */ + memAccess, /* xAccess */ + memFullPathname, /* xFullPathname */ + memDlOpen, /* xDlOpen */ + memDlError, /* xDlError */ + memDlSym, /* xDlSym */ + memDlClose, /* xDlClose */ + memRandomness, /* xRandomness */ + memSleep, /* xSleep */ + memCurrentTime, /* xCurrentTime */ + memGetLastError, /* xGetLastError */ + memCurrentTimeInt64 /* xCurrentTimeInt64 */ +}; + +static const sqlite3_io_methods mem_io_methods = { + 3, /* iVersion */ + memClose, /* xClose */ + memRead, /* xRead */ + memWrite, /* xWrite */ + memTruncate, /* xTruncate */ + memSync, /* xSync */ + memFileSize, /* xFileSize */ + memLock, /* xLock */ + memUnlock, /* xUnlock */ + memCheckReservedLock, /* xCheckReservedLock */ + memFileControl, /* xFileControl */ + memSectorSize, /* xSectorSize */ + memDeviceCharacteristics, /* xDeviceCharacteristics */ + memShmMap, /* xShmMap */ + memShmLock, /* xShmLock */ + memShmBarrier, /* xShmBarrier */ + memShmUnmap, /* xShmUnmap */ + memFetch, /* xFetch */ + memUnfetch /* xUnfetch */ +}; + + + +/* +** Close an mem-file. +** +** The pData pointer is owned by the application, so there is nothing +** to free. +*/ +static int memClose(sqlite3_file *pFile){ + MemFile *p = (MemFile *)pFile; + if( p->bFreeOnClose ) sqlite3_free(p->aData); + return SQLITE_OK; +} + +/* +** Read data from an mem-file. +*/ +static int memRead( + sqlite3_file *pFile, + void *zBuf, + int iAmt, + sqlite_int64 iOfst +){ + MemFile *p = (MemFile *)pFile; + memcpy(zBuf, p->aData+iOfst, iAmt); + return SQLITE_OK; +} + +/* +** Write data to an mem-file. +*/ +static int memWrite( + sqlite3_file *pFile, + const void *z, + int iAmt, + sqlite_int64 iOfst +){ + MemFile *p = (MemFile *)pFile; + if( iOfst+iAmt>p->sz ){ + if( iOfst+iAmt>p->szMax ) return SQLITE_FULL; + if( iOfst>p->sz ) memset(p->aData+p->sz, 0, iOfst-p->sz); + p->sz = iOfst+iAmt; + } + memcpy(p->aData+iOfst, z, iAmt); + return SQLITE_OK; +} + +/* +** Truncate an mem-file. +*/ +static int memTruncate(sqlite3_file *pFile, sqlite_int64 size){ + MemFile *p = (MemFile *)pFile; + if( size>p->sz ){ + if( size>p->szMax ) return SQLITE_FULL; + memset(p->aData+p->sz, 0, size-p->sz); + } + p->sz = size; + return SQLITE_OK; +} + +/* +** Sync an mem-file. +*/ +static int memSync(sqlite3_file *pFile, int flags){ + return SQLITE_OK; +} + +/* +** Return the current file-size of an mem-file. +*/ +static int memFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){ + MemFile *p = (MemFile *)pFile; + *pSize = p->sz; + return SQLITE_OK; +} + +/* +** Lock an mem-file. +*/ +static int memLock(sqlite3_file *pFile, int eLock){ + return SQLITE_OK; +} + +/* +** Unlock an mem-file. +*/ +static int memUnlock(sqlite3_file *pFile, int eLock){ + return SQLITE_OK; +} + +/* +** Check if another file-handle holds a RESERVED lock on an mem-file. +*/ +static int memCheckReservedLock(sqlite3_file *pFile, int *pResOut){ + *pResOut = 0; + return SQLITE_OK; +} + +/* +** File control method. For custom operations on an mem-file. +*/ +static int memFileControl(sqlite3_file *pFile, int op, void *pArg){ + MemFile *p = (MemFile *)pFile; + int rc = SQLITE_NOTFOUND; + if( op==SQLITE_FCNTL_VFSNAME ){ + *(char**)pArg = sqlite3_mprintf("mem(%p,%lld)", p->aData, p->sz); + rc = SQLITE_OK; + } + return rc; +} + +/* +** Return the sector-size in bytes for an mem-file. +*/ +static int memSectorSize(sqlite3_file *pFile){ + return 1024; +} + +/* +** Return the device characteristic flags supported by an mem-file. +*/ +static int memDeviceCharacteristics(sqlite3_file *pFile){ + return SQLITE_IOCAP_ATOMIC | + SQLITE_IOCAP_POWERSAFE_OVERWRITE | + SQLITE_IOCAP_SAFE_APPEND | + SQLITE_IOCAP_SEQUENTIAL; +} + +/* Create a shared memory file mapping */ +static int memShmMap( + sqlite3_file *pFile, + int iPg, + int pgsz, + int bExtend, + void volatile **pp +){ + return SQLITE_IOERR_SHMMAP; +} + +/* Perform locking on a shared-memory segment */ +static int memShmLock(sqlite3_file *pFile, int offset, int n, int flags){ + return SQLITE_IOERR_SHMLOCK; +} + +/* Memory barrier operation on shared memory */ +static void memShmBarrier(sqlite3_file *pFile){ + return; +} + +/* Unmap a shared memory segment */ +static int memShmUnmap(sqlite3_file *pFile, int deleteFlag){ + return SQLITE_OK; +} + +/* Fetch a page of a memory-mapped file */ +static int memFetch( + sqlite3_file *pFile, + sqlite3_int64 iOfst, + int iAmt, + void **pp +){ + MemFile *p = (MemFile *)pFile; + *pp = (void*)(p->aData + iOfst); + return SQLITE_OK; +} + +/* Release a memory-mapped page */ +static int memUnfetch(sqlite3_file *pFile, sqlite3_int64 iOfst, void *pPage){ + return SQLITE_OK; +} + +/* +** Open an mem file handle. +*/ +static int memOpen( + sqlite3_vfs *pVfs, + const char *zName, + sqlite3_file *pFile, + int flags, + int *pOutFlags +){ + MemFile *p = (MemFile*)pFile; + memset(p, 0, sizeof(*p)); + if( (flags & SQLITE_OPEN_MAIN_DB)==0 ) return SQLITE_CANTOPEN; + p->aData = (unsigned char*)sqlite3_uri_int64(zName,"ptr",0); + if( p->aData==0 ) return SQLITE_CANTOPEN; + p->sz = sqlite3_uri_int64(zName,"sz",0); + if( p->sz<0 ) return SQLITE_CANTOPEN; + p->szMax = sqlite3_uri_int64(zName,"max",p->sz); + if( p->szMax<p->sz ) return SQLITE_CANTOPEN; + p->bFreeOnClose = sqlite3_uri_boolean(zName,"freeonclose",0); + pFile->pMethods = &mem_io_methods; + return SQLITE_OK; +} + +/* +** Delete the file located at zPath. If the dirSync argument is true, +** ensure the file-system modifications are synced to disk before +** returning. +*/ +static int memDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){ + return SQLITE_IOERR_DELETE; +} + +/* +** Test for access permissions. Return true if the requested permission +** is available, or false otherwise. +*/ +static int memAccess( + sqlite3_vfs *pVfs, + const char *zPath, + int flags, + int *pResOut +){ + *pResOut = 0; + return SQLITE_OK; +} + +/* +** Populate buffer zOut with the full canonical pathname corresponding +** to the pathname in zPath. zOut is guaranteed to point to a buffer +** of at least (INST_MAX_PATHNAME+1) bytes. +*/ +static int memFullPathname( + sqlite3_vfs *pVfs, + const char *zPath, + int nOut, + char *zOut +){ + sqlite3_snprintf(nOut, zOut, "%s", zPath); + return SQLITE_OK; +} + +/* +** Open the dynamic library located at zPath and return a handle. +*/ +static void *memDlOpen(sqlite3_vfs *pVfs, const char *zPath){ + return ORIGVFS(pVfs)->xDlOpen(ORIGVFS(pVfs), zPath); +} + +/* +** Populate the buffer zErrMsg (size nByte bytes) with a human readable +** utf-8 string describing the most recent error encountered associated +** with dynamic libraries. +*/ +static void memDlError(sqlite3_vfs *pVfs, int nByte, char *zErrMsg){ + ORIGVFS(pVfs)->xDlError(ORIGVFS(pVfs), nByte, zErrMsg); +} + +/* +** Return a pointer to the symbol zSymbol in the dynamic library pHandle. +*/ +static void (*memDlSym(sqlite3_vfs *pVfs, void *p, const char *zSym))(void){ + return ORIGVFS(pVfs)->xDlSym(ORIGVFS(pVfs), p, zSym); +} + +/* +** Close the dynamic library handle pHandle. +*/ +static void memDlClose(sqlite3_vfs *pVfs, void *pHandle){ + ORIGVFS(pVfs)->xDlClose(ORIGVFS(pVfs), pHandle); +} + +/* +** Populate the buffer pointed to by zBufOut with nByte bytes of +** random data. +*/ +static int memRandomness(sqlite3_vfs *pVfs, int nByte, char *zBufOut){ + return ORIGVFS(pVfs)->xRandomness(ORIGVFS(pVfs), nByte, zBufOut); +} + +/* +** Sleep for nMicro microseconds. Return the number of microseconds +** actually slept. +*/ +static int memSleep(sqlite3_vfs *pVfs, int nMicro){ + return ORIGVFS(pVfs)->xSleep(ORIGVFS(pVfs), nMicro); +} + +/* +** Return the current time as a Julian Day number in *pTimeOut. +*/ +static int memCurrentTime(sqlite3_vfs *pVfs, double *pTimeOut){ + return ORIGVFS(pVfs)->xCurrentTime(ORIGVFS(pVfs), pTimeOut); +} + +static int memGetLastError(sqlite3_vfs *pVfs, int a, char *b){ + return ORIGVFS(pVfs)->xGetLastError(ORIGVFS(pVfs), a, b); +} +static int memCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *p){ + return ORIGVFS(pVfs)->xCurrentTimeInt64(ORIGVFS(pVfs), p); +} + +#ifdef MEMVFS_TEST +/* +** memvfs_from_file(FILENAME, MAXSIZE) +** +** This an SQL function used to help in testing the memvfs VFS. The +** function reads the content of a file into memory and then returns +** a URI that can be handed to ATTACH to attach the memory buffer as +** a database. Example: +** +** ATTACH memvfs_from_file('test.db',1048576) AS inmem; +** +** The optional MAXSIZE argument gives the size of the memory allocation +** used to hold the database. If omitted, it defaults to the size of the +** file on disk. +*/ +#include <stdio.h> +static void memvfsFromFileFunc( + sqlite3_context *context, + int argc, + sqlite3_value **argv +){ + unsigned char *p; + sqlite3_int64 sz; + sqlite3_int64 szMax; + FILE *in; + const char *zFilename = (const char*)sqlite3_value_text(argv[0]); + char *zUri; + + if( zFilename==0 ) return; + in = fopen(zFilename, "rb"); + if( in==0 ) return; + fseek(in, 0, SEEK_END); + szMax = sz = ftell(in); + rewind(in); + if( argc>=2 ){ + szMax = sqlite3_value_int64(argv[1]); + if( szMax<sz ) szMax = sz; + } + p = sqlite3_malloc64( szMax ); + if( p==0 ){ + fclose(in); + sqlite3_result_error_nomem(context); + return; + } + fread(p, sz, 1, in); + fclose(in); + zUri = sqlite3_mprintf( + "file:/mem?vfs=memvfs&ptr=%lld&sz=%lld&max=%lld&freeonclose=1", + (sqlite3_int64)p, sz, szMax); + sqlite3_result_text(context, zUri, -1, sqlite3_free); +} +#endif /* MEMVFS_TEST */ + +#ifdef MEMVFS_TEST +/* +** memvfs_to_file(SCHEMA, FILENAME) +** +** The schema identified by SCHEMA must be a memvfs database. Write +** the content of this database into FILENAME. +*/ +static void memvfsToFileFunc( + sqlite3_context *context, + int argc, + sqlite3_value **argv +){ + MemFile *p = 0; + FILE *out; + int rc; + sqlite3 *db = sqlite3_context_db_handle(context); + sqlite3_vfs *pVfs = 0; + const char *zSchema = (const char*)sqlite3_value_text(argv[0]); + const char *zFilename = (const char*)sqlite3_value_text(argv[1]); + + if( zFilename==0 ) return; + out = fopen(zFilename, "wb"); + if( out==0 ) return; + rc = sqlite3_file_control(db, zSchema, SQLITE_FCNTL_VFS_POINTER, &pVfs); + if( rc || pVfs==0 ) return; + if( strcmp(pVfs->zName,"memvfs")!=0 ) return; + rc = sqlite3_file_control(db, zSchema, SQLITE_FCNTL_FILE_POINTER, &p); + if( rc ) return; + fwrite(p->aData, 1, (size_t)p->sz, out); + fclose(out); +} +#endif /* MEMVFS_TEST */ + +#ifdef MEMVFS_TEST +/* Called for each new database connection */ +static int memvfsRegister( + sqlite3 *db, + char **pzErrMsg, + const struct sqlite3_api_routines *pThunk +){ + sqlite3_create_function(db, "memvfs_from_file", 1, SQLITE_UTF8, 0, + memvfsFromFileFunc, 0, 0); + sqlite3_create_function(db, "memvfs_from_file", 2, SQLITE_UTF8, 0, + memvfsFromFileFunc, 0, 0); + sqlite3_create_function(db, "memvfs_to_file", 2, SQLITE_UTF8, 0, + memvfsToFileFunc, 0, 0); + return SQLITE_OK; +} +#endif /* MEMVFS_TEST */ + + +#ifdef _WIN32 +__declspec(dllexport) +#endif +/* +** This routine is called when the extension is loaded. +** Register the new VFS. +*/ +int sqlite3_memvfs_init( + sqlite3 *db, + char **pzErrMsg, + const sqlite3_api_routines *pApi +){ + int rc = SQLITE_OK; + SQLITE_EXTENSION_INIT2(pApi); + mem_vfs.pAppData = sqlite3_vfs_find(0); + if( mem_vfs.pAppData==0 ) return SQLITE_ERROR; + mem_vfs.szOsFile = sizeof(MemFile); + rc = sqlite3_vfs_register(&mem_vfs, 1); +#ifdef MEMVFS_TEST + if( rc==SQLITE_OK ){ + rc = sqlite3_auto_extension((void(*)(void))memvfsRegister); + } + if( rc==SQLITE_OK ){ + rc = memvfsRegister(db, pzErrMsg, pApi); + } +#endif + if( rc==SQLITE_OK ) rc = SQLITE_OK_LOAD_PERMANENTLY; + return rc; +} |