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/*
** 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 file implements an in-memory VFS. A database is held as a contiguous
** block of memory.
**
** This file also implements interface sqlite3_serialize() and
** sqlite3_deserialize().
*/
#include "sqliteInt.h"
#ifdef SQLITE_ENABLE_DESERIALIZE
/*
** 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 szAlloc; /* Space allocated to aData */
sqlite3_int64 szMax; /* Maximum allowed size of the file */
unsigned char *aData; /* content of the file */
int nMmap; /* Number of memory mapped pages */
unsigned mFlags; /* Flags */
int eLock; /* Most recent lock against this file */
};
/*
** Methods for MemFile
*/
static int memdbClose(sqlite3_file*);
static int memdbRead(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
static int memdbWrite(sqlite3_file*,const void*,int iAmt, sqlite3_int64 iOfst);
static int memdbTruncate(sqlite3_file*, sqlite3_int64 size);
static int memdbSync(sqlite3_file*, int flags);
static int memdbFileSize(sqlite3_file*, sqlite3_int64 *pSize);
static int memdbLock(sqlite3_file*, int);
/* static int memdbCheckReservedLock(sqlite3_file*, int *pResOut);// not used */
static int memdbFileControl(sqlite3_file*, int op, void *pArg);
/* static int memdbSectorSize(sqlite3_file*); // not used */
static int memdbDeviceCharacteristics(sqlite3_file*);
static int memdbFetch(sqlite3_file*, sqlite3_int64 iOfst, int iAmt, void **pp);
static int memdbUnfetch(sqlite3_file*, sqlite3_int64 iOfst, void *p);
/*
** Methods for MemVfs
*/
static int memdbOpen(sqlite3_vfs*, const char *, sqlite3_file*, int , int *);
/* static int memdbDelete(sqlite3_vfs*, const char *zName, int syncDir); */
static int memdbAccess(sqlite3_vfs*, const char *zName, int flags, int *);
static int memdbFullPathname(sqlite3_vfs*, const char *zName, int, char *zOut);
static void *memdbDlOpen(sqlite3_vfs*, const char *zFilename);
static void memdbDlError(sqlite3_vfs*, int nByte, char *zErrMsg);
static void (*memdbDlSym(sqlite3_vfs *pVfs, void *p, const char*zSym))(void);
static void memdbDlClose(sqlite3_vfs*, void*);
static int memdbRandomness(sqlite3_vfs*, int nByte, char *zOut);
static int memdbSleep(sqlite3_vfs*, int microseconds);
/* static int memdbCurrentTime(sqlite3_vfs*, double*); */
static int memdbGetLastError(sqlite3_vfs*, int, char *);
static int memdbCurrentTimeInt64(sqlite3_vfs*, sqlite3_int64*);
static sqlite3_vfs memdb_vfs = {
2, /* iVersion */
0, /* szOsFile (set when registered) */
1024, /* mxPathname */
0, /* pNext */
"memdb", /* zName */
0, /* pAppData (set when registered) */
memdbOpen, /* xOpen */
0, /* memdbDelete, */ /* xDelete */
memdbAccess, /* xAccess */
memdbFullPathname, /* xFullPathname */
memdbDlOpen, /* xDlOpen */
memdbDlError, /* xDlError */
memdbDlSym, /* xDlSym */
memdbDlClose, /* xDlClose */
memdbRandomness, /* xRandomness */
memdbSleep, /* xSleep */
0, /* memdbCurrentTime, */ /* xCurrentTime */
memdbGetLastError, /* xGetLastError */
memdbCurrentTimeInt64 /* xCurrentTimeInt64 */
};
static const sqlite3_io_methods memdb_io_methods = {
3, /* iVersion */
memdbClose, /* xClose */
memdbRead, /* xRead */
memdbWrite, /* xWrite */
memdbTruncate, /* xTruncate */
memdbSync, /* xSync */
memdbFileSize, /* xFileSize */
memdbLock, /* xLock */
memdbLock, /* xUnlock - same as xLock in this case */
0, /* memdbCheckReservedLock, */ /* xCheckReservedLock */
memdbFileControl, /* xFileControl */
0, /* memdbSectorSize,*/ /* xSectorSize */
memdbDeviceCharacteristics, /* xDeviceCharacteristics */
0, /* xShmMap */
0, /* xShmLock */
0, /* xShmBarrier */
0, /* xShmUnmap */
memdbFetch, /* xFetch */
memdbUnfetch /* xUnfetch */
};
/*
** Close an memdb-file.
**
** The pData pointer is owned by the application, so there is nothing
** to free.
*/
static int memdbClose(sqlite3_file *pFile){
MemFile *p = (MemFile *)pFile;
if( p->mFlags & SQLITE_DESERIALIZE_FREEONCLOSE ) sqlite3_free(p->aData);
return SQLITE_OK;
}
/*
** Read data from an memdb-file.
*/
static int memdbRead(
sqlite3_file *pFile,
void *zBuf,
int iAmt,
sqlite_int64 iOfst
){
MemFile *p = (MemFile *)pFile;
if( iOfst+iAmt>p->sz ){
memset(zBuf, 0, iAmt);
if( iOfst<p->sz ) memcpy(zBuf, p->aData+iOfst, p->sz - iOfst);
return SQLITE_IOERR_SHORT_READ;
}
memcpy(zBuf, p->aData+iOfst, iAmt);
return SQLITE_OK;
}
/*
** Try to enlarge the memory allocation to hold at least sz bytes
*/
static int memdbEnlarge(MemFile *p, sqlite3_int64 newSz){
unsigned char *pNew;
if( (p->mFlags & SQLITE_DESERIALIZE_RESIZEABLE)==0 || p->nMmap>0 ){
return SQLITE_FULL;
}
if( newSz>p->szMax ){
return SQLITE_FULL;
}
newSz *= 2;
if( newSz>p->szMax ) newSz = p->szMax;
pNew = sqlite3Realloc(p->aData, newSz);
if( pNew==0 ) return SQLITE_NOMEM;
p->aData = pNew;
p->szAlloc = newSz;
return SQLITE_OK;
}
/*
** Write data to an memdb-file.
*/
static int memdbWrite(
sqlite3_file *pFile,
const void *z,
int iAmt,
sqlite_int64 iOfst
){
MemFile *p = (MemFile *)pFile;
if( NEVER(p->mFlags & SQLITE_DESERIALIZE_READONLY) ) return SQLITE_READONLY;
if( iOfst+iAmt>p->sz ){
int rc;
if( iOfst+iAmt>p->szAlloc
&& (rc = memdbEnlarge(p, iOfst+iAmt))!=SQLITE_OK
){
return rc;
}
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 memdb-file.
**
** In rollback mode (which is always the case for memdb, as it does not
** support WAL mode) the truncate() method is only used to reduce
** the size of a file, never to increase the size.
*/
static int memdbTruncate(sqlite3_file *pFile, sqlite_int64 size){
MemFile *p = (MemFile *)pFile;
if( NEVER(size>p->sz) ) return SQLITE_FULL;
p->sz = size;
return SQLITE_OK;
}
/*
** Sync an memdb-file.
*/
static int memdbSync(sqlite3_file *pFile, int flags){
return SQLITE_OK;
}
/*
** Return the current file-size of an memdb-file.
*/
static int memdbFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){
MemFile *p = (MemFile *)pFile;
*pSize = p->sz;
return SQLITE_OK;
}
/*
** Lock an memdb-file.
*/
static int memdbLock(sqlite3_file *pFile, int eLock){
MemFile *p = (MemFile *)pFile;
if( eLock>SQLITE_LOCK_SHARED
&& (p->mFlags & SQLITE_DESERIALIZE_READONLY)!=0
){
return SQLITE_READONLY;
}
p->eLock = eLock;
return SQLITE_OK;
}
#if 0 /* Never used because memdbAccess() always returns false */
/*
** Check if another file-handle holds a RESERVED lock on an memdb-file.
*/
static int memdbCheckReservedLock(sqlite3_file *pFile, int *pResOut){
*pResOut = 0;
return SQLITE_OK;
}
#endif
/*
** File control method. For custom operations on an memdb-file.
*/
static int memdbFileControl(sqlite3_file *pFile, int op, void *pArg){
MemFile *p = (MemFile *)pFile;
int rc = SQLITE_NOTFOUND;
if( op==SQLITE_FCNTL_VFSNAME ){
*(char**)pArg = sqlite3_mprintf("memdb(%p,%lld)", p->aData, p->sz);
rc = SQLITE_OK;
}
if( op==SQLITE_FCNTL_SIZE_LIMIT ){
sqlite3_int64 iLimit = *(sqlite3_int64*)pArg;
if( iLimit<p->sz ){
if( iLimit<0 ){
iLimit = p->szMax;
}else{
iLimit = p->sz;
}
}
p->szMax = iLimit;
*(sqlite3_int64*)pArg = iLimit;
rc = SQLITE_OK;
}
return rc;
}
#if 0 /* Not used because of SQLITE_IOCAP_POWERSAFE_OVERWRITE */
/*
** Return the sector-size in bytes for an memdb-file.
*/
static int memdbSectorSize(sqlite3_file *pFile){
return 1024;
}
#endif
/*
** Return the device characteristic flags supported by an memdb-file.
*/
static int memdbDeviceCharacteristics(sqlite3_file *pFile){
return SQLITE_IOCAP_ATOMIC |
SQLITE_IOCAP_POWERSAFE_OVERWRITE |
SQLITE_IOCAP_SAFE_APPEND |
SQLITE_IOCAP_SEQUENTIAL;
}
/* Fetch a page of a memory-mapped file */
static int memdbFetch(
sqlite3_file *pFile,
sqlite3_int64 iOfst,
int iAmt,
void **pp
){
MemFile *p = (MemFile *)pFile;
if( iOfst+iAmt>p->sz ){
*pp = 0;
}else{
p->nMmap++;
*pp = (void*)(p->aData + iOfst);
}
return SQLITE_OK;
}
/* Release a memory-mapped page */
static int memdbUnfetch(sqlite3_file *pFile, sqlite3_int64 iOfst, void *pPage){
MemFile *p = (MemFile *)pFile;
p->nMmap--;
return SQLITE_OK;
}
/*
** Open an mem file handle.
*/
static int memdbOpen(
sqlite3_vfs *pVfs,
const char *zName,
sqlite3_file *pFile,
int flags,
int *pOutFlags
){
MemFile *p = (MemFile*)pFile;
if( (flags & SQLITE_OPEN_MAIN_DB)==0 ){
return ORIGVFS(pVfs)->xOpen(ORIGVFS(pVfs), zName, pFile, flags, pOutFlags);
}
memset(p, 0, sizeof(*p));
p->mFlags = SQLITE_DESERIALIZE_RESIZEABLE | SQLITE_DESERIALIZE_FREEONCLOSE;
assert( pOutFlags!=0 ); /* True because flags==SQLITE_OPEN_MAIN_DB */
*pOutFlags = flags | SQLITE_OPEN_MEMORY;
pFile->pMethods = &memdb_io_methods;
p->szMax = sqlite3GlobalConfig.mxMemdbSize;
return SQLITE_OK;
}
#if 0 /* Only used to delete rollback journals, super-journals, and WAL
** files, none of which exist in memdb. So this routine is never used */
/*
** 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 memdbDelete(sqlite3_vfs *pVfs, const char *zPath, int dirSync){
return SQLITE_IOERR_DELETE;
}
#endif
/*
** Test for access permissions. Return true if the requested permission
** is available, or false otherwise.
**
** With memdb, no files ever exist on disk. So always return false.
*/
static int memdbAccess(
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 memdbFullPathname(
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 *memdbDlOpen(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 memdbDlError(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 (*memdbDlSym(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 memdbDlClose(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 memdbRandomness(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 memdbSleep(sqlite3_vfs *pVfs, int nMicro){
return ORIGVFS(pVfs)->xSleep(ORIGVFS(pVfs), nMicro);
}
#if 0 /* Never used. Modern cores only call xCurrentTimeInt64() */
/*
** Return the current time as a Julian Day number in *pTimeOut.
*/
static int memdbCurrentTime(sqlite3_vfs *pVfs, double *pTimeOut){
return ORIGVFS(pVfs)->xCurrentTime(ORIGVFS(pVfs), pTimeOut);
}
#endif
static int memdbGetLastError(sqlite3_vfs *pVfs, int a, char *b){
return ORIGVFS(pVfs)->xGetLastError(ORIGVFS(pVfs), a, b);
}
static int memdbCurrentTimeInt64(sqlite3_vfs *pVfs, sqlite3_int64 *p){
return ORIGVFS(pVfs)->xCurrentTimeInt64(ORIGVFS(pVfs), p);
}
/*
** Translate a database connection pointer and schema name into a
** MemFile pointer.
*/
static MemFile *memdbFromDbSchema(sqlite3 *db, const char *zSchema){
MemFile *p = 0;
int rc = sqlite3_file_control(db, zSchema, SQLITE_FCNTL_FILE_POINTER, &p);
if( rc ) return 0;
if( p->base.pMethods!=&memdb_io_methods ) return 0;
return p;
}
/*
** Return the serialization of a database
*/
unsigned char *sqlite3_serialize(
sqlite3 *db, /* The database connection */
const char *zSchema, /* Which database within the connection */
sqlite3_int64 *piSize, /* Write size here, if not NULL */
unsigned int mFlags /* Maybe SQLITE_SERIALIZE_NOCOPY */
){
MemFile *p;
int iDb;
Btree *pBt;
sqlite3_int64 sz;
int szPage = 0;
sqlite3_stmt *pStmt = 0;
unsigned char *pOut;
char *zSql;
int rc;
#ifdef SQLITE_ENABLE_API_ARMOR
if( !sqlite3SafetyCheckOk(db) ){
(void)SQLITE_MISUSE_BKPT;
return 0;
}
#endif
if( zSchema==0 ) zSchema = db->aDb[0].zDbSName;
p = memdbFromDbSchema(db, zSchema);
iDb = sqlite3FindDbName(db, zSchema);
if( piSize ) *piSize = -1;
if( iDb<0 ) return 0;
if( p ){
if( piSize ) *piSize = p->sz;
if( mFlags & SQLITE_SERIALIZE_NOCOPY ){
pOut = p->aData;
}else{
pOut = sqlite3_malloc64( p->sz );
if( pOut ) memcpy(pOut, p->aData, p->sz);
}
return pOut;
}
pBt = db->aDb[iDb].pBt;
if( pBt==0 ) return 0;
szPage = sqlite3BtreeGetPageSize(pBt);
zSql = sqlite3_mprintf("PRAGMA \"%w\".page_count", zSchema);
rc = zSql ? sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0) : SQLITE_NOMEM;
sqlite3_free(zSql);
if( rc ) return 0;
rc = sqlite3_step(pStmt);
if( rc!=SQLITE_ROW ){
pOut = 0;
}else{
sz = sqlite3_column_int64(pStmt, 0)*szPage;
if( piSize ) *piSize = sz;
if( mFlags & SQLITE_SERIALIZE_NOCOPY ){
pOut = 0;
}else{
pOut = sqlite3_malloc64( sz );
if( pOut ){
int nPage = sqlite3_column_int(pStmt, 0);
Pager *pPager = sqlite3BtreePager(pBt);
int pgno;
for(pgno=1; pgno<=nPage; pgno++){
DbPage *pPage = 0;
unsigned char *pTo = pOut + szPage*(sqlite3_int64)(pgno-1);
rc = sqlite3PagerGet(pPager, pgno, (DbPage**)&pPage, 0);
if( rc==SQLITE_OK ){
memcpy(pTo, sqlite3PagerGetData(pPage), szPage);
}else{
memset(pTo, 0, szPage);
}
sqlite3PagerUnref(pPage);
}
}
}
}
sqlite3_finalize(pStmt);
return pOut;
}
/* Convert zSchema to a MemDB and initialize its content.
*/
int sqlite3_deserialize(
sqlite3 *db, /* The database connection */
const char *zSchema, /* Which DB to reopen with the deserialization */
unsigned char *pData, /* The serialized database content */
sqlite3_int64 szDb, /* Number bytes in the deserialization */
sqlite3_int64 szBuf, /* Total size of buffer pData[] */
unsigned mFlags /* Zero or more SQLITE_DESERIALIZE_* flags */
){
MemFile *p;
char *zSql;
sqlite3_stmt *pStmt = 0;
int rc;
int iDb;
#ifdef SQLITE_ENABLE_API_ARMOR
if( !sqlite3SafetyCheckOk(db) ){
return SQLITE_MISUSE_BKPT;
}
if( szDb<0 ) return SQLITE_MISUSE_BKPT;
if( szBuf<0 ) return SQLITE_MISUSE_BKPT;
#endif
sqlite3_mutex_enter(db->mutex);
if( zSchema==0 ) zSchema = db->aDb[0].zDbSName;
iDb = sqlite3FindDbName(db, zSchema);
if( iDb<0 ){
rc = SQLITE_ERROR;
goto end_deserialize;
}
zSql = sqlite3_mprintf("ATTACH x AS %Q", zSchema);
rc = sqlite3_prepare_v2(db, zSql, -1, &pStmt, 0);
sqlite3_free(zSql);
if( rc ) goto end_deserialize;
db->init.iDb = (u8)iDb;
db->init.reopenMemdb = 1;
rc = sqlite3_step(pStmt);
db->init.reopenMemdb = 0;
if( rc!=SQLITE_DONE ){
rc = SQLITE_ERROR;
goto end_deserialize;
}
p = memdbFromDbSchema(db, zSchema);
if( p==0 ){
rc = SQLITE_ERROR;
}else{
p->aData = pData;
p->sz = szDb;
p->szAlloc = szBuf;
p->szMax = szBuf;
if( p->szMax<sqlite3GlobalConfig.mxMemdbSize ){
p->szMax = sqlite3GlobalConfig.mxMemdbSize;
}
p->mFlags = mFlags;
rc = SQLITE_OK;
}
end_deserialize:
sqlite3_finalize(pStmt);
sqlite3_mutex_leave(db->mutex);
return rc;
}
/*
** This routine is called when the extension is loaded.
** Register the new VFS.
*/
int sqlite3MemdbInit(void){
sqlite3_vfs *pLower = sqlite3_vfs_find(0);
int sz = pLower->szOsFile;
memdb_vfs.pAppData = pLower;
/* The following conditional can only be true when compiled for
** Windows x86 and SQLITE_MAX_MMAP_SIZE=0. We always leave
** it in, to be safe, but it is marked as NO_TEST since there
** is no way to reach it under most builds. */
if( sz<sizeof(MemFile) ) sz = sizeof(MemFile); /*NO_TEST*/
memdb_vfs.szOsFile = sz;
return sqlite3_vfs_register(&memdb_vfs, 0);
}
#endif /* SQLITE_ENABLE_DESERIALIZE */