/*
** 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;
}