sqlcipher/src/memdb.c at sqlite-release · sqlcipher/sqlcipher · GitHub

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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"

#ifndef SQLITE_OMIT_DESERIALIZE

** Forward declaration of objects used by this utility

typedef struct sqlite3_vfs MemVfs;

typedef struct MemFile MemFile;

typedef struct MemStore MemStore;

/* Access to a lower-level VFS that (might) implement dynamic loading,

** access to randomness, etc.

#define ORIGVFS(p) ((sqlite3_vfs*)((p)->pAppData))

/* Storage for a memdb file.

** An memdb object can be shared or separate. Shared memdb objects can be

** used by more than one database connection. Mutexes are used by shared

** memdb objects to coordinate access. Separate memdb objects are only

** connected to a single database connection and do not require additional

** mutexes.

** Shared memdb objects have .zFName!=0 and .pMutex!=0. They are created

** using "file:/name?vfs=memdb". The first character of the name must be

** "/" or else the object will be a separate memdb object. All shared

** memdb objects are stored in memdb_g.apMemStore[] in an arbitrary order.

** Separate memdb objects are created using a name that does not begin

** with "/" or using sqlite3_deserialize().

** Access rules for shared MemStore objects:

** * .zFName is initialized when the object is created and afterwards

** is unchanged until the object is destroyed. So it can be accessed

** at any time as long as we know the object is not being destroyed,

** which means while either the SQLITE_MUTEX_STATIC_VFS1 or

** .pMutex is held or the object is not part of memdb_g.apMemStore[].

** * Can .pMutex can only be changed while holding the

** SQLITE_MUTEX_STATIC_VFS1 mutex or while the object is not part

** of memdb_g.apMemStore[].

** * Other fields can only be changed while holding the .pMutex mutex

** or when the .nRef is less than zero and the object is not part of

** memdb_g.apMemStore[].

** * The .aData pointer has the added requirement that it can can only

** be changed (for resizing) when nMmap is zero.

struct MemStore {

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 */

sqlite3_mutex *pMutex; /* Used by shared stores only */

int nMmap; /* Number of memory mapped pages */

unsigned mFlags; /* Flags */

int nRdLock; /* Number of readers */

int nWrLock; /* Number of writers. (Always 0 or 1) */

int nRef; /* Number of users of this MemStore */

char *zFName; /* The filename for shared stores */

};

/* An open file */

struct MemFile {

sqlite3_file base; /* IO methods */

MemStore *pStore; /* The storage */

int eLock; /* Most recent lock against this file */

};

** File-scope variables for holding the memdb files that are accessible

** to multiple database connections in separate threads.

** Must hold SQLITE_MUTEX_STATIC_VFS1 to access any part of this object.

static struct MemFS {

int nMemStore; /* Number of shared MemStore objects */

MemStore **apMemStore; /* Array of all shared MemStore objects */

} memdb_g;

** 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 memdbUnlock(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 */

0, /* xSetSystemCall */

0, /* xGetSystemCall */

0, /* xNextSystemCall */

};

static const sqlite3_io_methods memdb_io_methods = {

3, /* iVersion */

memdbClose, /* xClose */

memdbRead, /* xRead */

memdbWrite, /* xWrite */

memdbTruncate, /* xTruncate */

memdbSync, /* xSync */

memdbFileSize, /* xFileSize */

memdbLock, /* xLock */

memdbUnlock, /* xUnlock */

0, /* memdbCheckReservedLock, */ /* xCheckReservedLock */

memdbFileControl, /* xFileControl */

0, /* memdbSectorSize,*/ /* xSectorSize */

memdbDeviceCharacteristics, /* xDeviceCharacteristics */

0, /* xShmMap */

0, /* xShmLock */

0, /* xShmBarrier */

0, /* xShmUnmap */

memdbFetch, /* xFetch */

memdbUnfetch /* xUnfetch */

};

** Enter/leave the mutex on a MemStore

#if defined(SQLITE_THREADSAFE) && SQLITE_THREADSAFE==0

static void memdbEnter(MemStore *p){

UNUSED_PARAMETER(p);

}

static void memdbLeave(MemStore *p){

UNUSED_PARAMETER(p);

}

#else

static void memdbEnter(MemStore *p){

sqlite3_mutex_enter(p->pMutex);

}

static void memdbLeave(MemStore *p){

sqlite3_mutex_leave(p->pMutex);

}

#endif

** Close an memdb-file.

** Free the underlying MemStore object when its refcount drops to zero

** or less.

static int memdbClose(sqlite3_file *pFile){

MemStore *p = ((MemFile*)pFile)->pStore;

if( p->zFName ){

int i;

#ifndef SQLITE_MUTEX_OMIT

sqlite3_mutex *pVfsMutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS1);

#endif

sqlite3_mutex_enter(pVfsMutex);

for(i=0; ALWAYS(i<memdb_g.nMemStore); i++){

if( memdb_g.apMemStore[i]==p ){

memdbEnter(p);

if( p->nRef==1 ){

memdb_g.apMemStore[i] = memdb_g.apMemStore[--memdb_g.nMemStore];

if( memdb_g.nMemStore==0 ){

sqlite3_free(memdb_g.apMemStore);

memdb_g.apMemStore = 0;

}

break;

}

sqlite3_mutex_leave(pVfsMutex);

}else{

memdbEnter(p);

}

p->nRef--;

if( p->nRef<=0 ){

if( p->mFlags & SQLITE_DESERIALIZE_FREEONCLOSE ){

sqlite3_free(p->aData);

}

memdbLeave(p);

sqlite3_mutex_free(p->pMutex);

sqlite3_free(p);

}else{

memdbLeave(p);

}

return SQLITE_OK;

}

** Read data from an memdb-file.

static int memdbRead(

sqlite3_file *pFile,

void *zBuf,

int iAmt,

sqlite_int64 iOfst

){

MemStore *p = ((MemFile*)pFile)->pStore;

memdbEnter(p);

if( iOfst+iAmt>p->sz ){

memset(zBuf, 0, iAmt);

if( iOfst<p->sz ) memcpy(zBuf, p->aData+iOfst, p->sz - iOfst);

memdbLeave(p);

return SQLITE_IOERR_SHORT_READ;

}

memcpy(zBuf, p->aData+iOfst, iAmt);

memdbLeave(p);

return SQLITE_OK;

}

** Try to enlarge the memory allocation to hold at least sz bytes

static int memdbEnlarge(MemStore *p, sqlite3_int64 newSz){

unsigned char *pNew;

if( (p->mFlags & SQLITE_DESERIALIZE_RESIZEABLE)==0 || NEVER(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_IOERR_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

){

MemStore *p = ((MemFile*)pFile)->pStore;

memdbEnter(p);

if( NEVER(p->mFlags & SQLITE_DESERIALIZE_READONLY) ){

/* Can't happen: memdbLock() will return SQLITE_READONLY before

** reaching this point */

memdbLeave(p);

return SQLITE_IOERR_WRITE;

}

if( iOfst+iAmt>p->sz ){

int rc;

if( iOfst+iAmt>p->szAlloc

&& (rc = memdbEnlarge(p, iOfst+iAmt))!=SQLITE_OK

){

memdbLeave(p);

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);

memdbLeave(p);

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){

MemStore *p = ((MemFile*)pFile)->pStore;

int rc = SQLITE_OK;

memdbEnter(p);

if( size>p->sz ){

/* This can only happen with a corrupt wal mode db */

rc = SQLITE_CORRUPT;

}else{

p->sz = size;

}

memdbLeave(p);

return rc;

}

** Sync an memdb-file.

static int memdbSync(sqlite3_file *pFile, int flags){

UNUSED_PARAMETER(pFile);

UNUSED_PARAMETER(flags);

return SQLITE_OK;

}

** Return the current file-size of an memdb-file.

static int memdbFileSize(sqlite3_file *pFile, sqlite_int64 *pSize){

MemStore *p = ((MemFile*)pFile)->pStore;

memdbEnter(p);

*pSize = p->sz;

memdbLeave(p);

return SQLITE_OK;

}

** Lock an memdb-file.

static int memdbLock(sqlite3_file *pFile, int eLock){

MemFile *pThis = (MemFile*)pFile;

MemStore *p = pThis->pStore;

int rc = SQLITE_OK;

if( eLock<=pThis->eLock ) return SQLITE_OK;

memdbEnter(p);

assert( p->nWrLock==0 || p->nWrLock==1 );

assert( pThis->eLock<=SQLITE_LOCK_SHARED || p->nWrLock==1 );

assert( pThis->eLock==SQLITE_LOCK_NONE || p->nRdLock>=1 );

if( eLock>SQLITE_LOCK_SHARED && (p->mFlags & SQLITE_DESERIALIZE_READONLY) ){

rc = SQLITE_READONLY;

}else{

switch( eLock ){

case SQLITE_LOCK_SHARED: {

assert( pThis->eLock==SQLITE_LOCK_NONE );

if( p->nWrLock>0 ){

rc = SQLITE_BUSY;

}else{

p->nRdLock++;

}

break;

};

case SQLITE_LOCK_RESERVED:

case SQLITE_LOCK_PENDING: {

assert( pThis->eLock>=SQLITE_LOCK_SHARED );

if( ALWAYS(pThis->eLock==SQLITE_LOCK_SHARED) ){

if( p->nWrLock>0 ){

rc = SQLITE_BUSY;

}else{

p->nWrLock = 1;

}

break;

}

default: {

assert( eLock==SQLITE_LOCK_EXCLUSIVE );

assert( pThis->eLock>=SQLITE_LOCK_SHARED );

if( p->nRdLock>1 ){

rc = SQLITE_BUSY;

}else if( pThis->eLock==SQLITE_LOCK_SHARED ){

p->nWrLock = 1;

}

break;

}

if( rc==SQLITE_OK ) pThis->eLock = eLock;

memdbLeave(p);

return rc;

}

** Unlock an memdb-file.

static int memdbUnlock(sqlite3_file *pFile, int eLock){

MemFile *pThis = (MemFile*)pFile;

MemStore *p = pThis->pStore;

if( eLock>=pThis->eLock ) return SQLITE_OK;

memdbEnter(p);

assert( eLock==SQLITE_LOCK_SHARED || eLock==SQLITE_LOCK_NONE );

if( eLock==SQLITE_LOCK_SHARED ){

if( ALWAYS(pThis->eLock>SQLITE_LOCK_SHARED) ){

p->nWrLock--;

}

}else{

if( pThis->eLock>SQLITE_LOCK_SHARED ){

p->nWrLock--;

}

p->nRdLock--;

}

pThis->eLock = eLock;

memdbLeave(p);

return SQLITE_OK;

}

#if 0

** This interface is only used for crash recovery, which does not

** occur on an in-memory database.

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){

MemStore *p = ((MemFile*)pFile)->pStore;

int rc = SQLITE_NOTFOUND;

memdbEnter(p);

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;

}

memdbLeave(p);

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){

UNUSED_PARAMETER(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

){

MemStore *p = ((MemFile*)pFile)->pStore;

memdbEnter(p);

if( iOfst+iAmt>p->sz || (p->mFlags & SQLITE_DESERIALIZE_RESIZEABLE)!=0 ){

*pp = 0;

}else{

p->nMmap++;

*pp = (void*)(p->aData + iOfst);

}

memdbLeave(p);

return SQLITE_OK;

}

/* Release a memory-mapped page */

static int memdbUnfetch(sqlite3_file *pFile, sqlite3_int64 iOfst, void *pPage){

MemStore *p = ((MemFile*)pFile)->pStore;

UNUSED_PARAMETER(iOfst);

UNUSED_PARAMETER(pPage);

memdbEnter(p);

p->nMmap--;

memdbLeave(p);

return SQLITE_OK;

}

** Open an mem file handle.

static int memdbOpen(

sqlite3_vfs *pVfs,

const char *zName,

sqlite3_file *pFd,

int flags,

int *pOutFlags

){

MemFile *pFile = (MemFile*)pFd;

MemStore *p = 0;

int szName;

UNUSED_PARAMETER(pVfs);

memset(pFile, 0, sizeof(*pFile));

szName = sqlite3Strlen30(zName);

if( szName>1 && (zName[0]=='/' || zName[0]=='\\') ){

int i;

#ifndef SQLITE_MUTEX_OMIT

sqlite3_mutex *pVfsMutex = sqlite3MutexAlloc(SQLITE_MUTEX_STATIC_VFS1);

#endif

sqlite3_mutex_enter(pVfsMutex);

for(i=0; i<memdb_g.nMemStore; i++){

if( strcmp(memdb_g.apMemStore[i]->zFName,zName)==0 ){

p = memdb_g.apMemStore[i];

break;

}

if( p==0 ){

MemStore **apNew;

p = sqlite3Malloc( sizeof(*p) + (i64)szName + 3 );

if( p==0 ){

sqlite3_mutex_leave(pVfsMutex);

return SQLITE_NOMEM;

}

apNew = sqlite3Realloc(memdb_g.apMemStore,

sizeof(apNew[0])*(1+(i64)memdb_g.nMemStore) );

if( apNew==0 ){

sqlite3_free(p);

sqlite3_mutex_leave(pVfsMutex);

return SQLITE_NOMEM;

}

apNew[memdb_g.nMemStore++] = p;

memdb_g.apMemStore = apNew;

memset(p, 0, sizeof(*p));

p->mFlags = SQLITE_DESERIALIZE_RESIZEABLE|SQLITE_DESERIALIZE_FREEONCLOSE;

p->szMax = sqlite3GlobalConfig.mxMemdbSize;

p->zFName = (char*)&p[1];

memcpy(p->zFName, zName, szName+1);

p->pMutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);

if( p->pMutex==0 ){

memdb_g.nMemStore--;

sqlite3_free(p);

sqlite3_mutex_leave(pVfsMutex);

return SQLITE_NOMEM;

}

p->nRef = 1;

memdbEnter(p);

}else{

memdbEnter(p);

p->nRef++;

}

sqlite3_mutex_leave(pVfsMutex);

}else{

p = sqlite3Malloc( sizeof(*p) );

if( p==0 ){

return SQLITE_NOMEM;

}

memset(p, 0, sizeof(*p));

p->mFlags = SQLITE_DESERIALIZE_RESIZEABLE | SQLITE_DESERIALIZE_FREEONCLOSE;

p->szMax = sqlite3GlobalConfig.mxMemdbSize;

}

pFile->pStore = p;

if( pOutFlags!=0 ){

*pOutFlags = flags | SQLITE_OPEN_MEMORY;

}

pFd->pMethods = &memdb_io_methods;

memdbLeave(p);

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

){

UNUSED_PARAMETER(pVfs);

UNUSED_PARAMETER(zPath);

UNUSED_PARAMETER(flags);

*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

){

UNUSED_PARAMETER(pVfs);

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;

MemStore *pStore;

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;

pStore = p->pStore;

memdbEnter(pStore);

if( pStore->zFName!=0 ) p = 0;

memdbLeave(pStore);

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 = 0;

char *zSql;

int rc;

#ifdef SQLITE_ENABLE_API_ARMOR

if( !sqlite3SafetyCheckOk(db) ){

(void)SQLITE_MISUSE_BKPT;

return 0;

}

#endif

sqlite3_mutex_enter(db->mutex);

if( zSchema==0 ) zSchema = db->aDb[0].zDbSName;

p = memdbFromDbSchema(db, zSchema);

iDb = sqlite3FindDbName(db, zSchema);

if( piSize ) *piSize = -1;

if( iDb<0 ) goto serialize_out;

if( p ){

MemStore *pStore = p->pStore;

assert( pStore->pMutex==0 );

if( piSize ) *piSize = pStore->sz;

if( mFlags & SQLITE_SERIALIZE_NOCOPY ){

pOut = pStore->aData;

}else{

pOut = sqlite3_malloc64( pStore->sz );

if( pOut ) memcpy(pOut, pStore->aData, pStore->sz);

}

goto serialize_out;

}

pBt = db->aDb[iDb].pBt;

if( pBt==0 ) goto serialize_out;

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 ) goto serialize_out;

rc = sqlite3_step(pStmt);

if( rc==SQLITE_ROW ){

sz = sqlite3_column_int64(pStmt, 0)*szPage;

if( sz==0 ){

sqlite3_reset(pStmt);

sqlite3_exec(db, "BEGIN IMMEDIATE; COMMIT;", 0, 0, 0);

rc = sqlite3_step(pStmt);

if( rc==SQLITE_ROW ){

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);

serialize_out:

sqlite3_mutex_leave(db->mutex);

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);

testcase( iDb==1 );

if( iDb<2 && iDb!=0 ){

rc = SQLITE_ERROR;

goto end_deserialize;

}

zSql = sqlite3_mprintf("ATTACH x AS %Q", zSchema);

if( zSql==0 ){

rc = SQLITE_NOMEM;

}else{

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;

sqlite3_step(pStmt);

db->init.reopenMemdb = 0;

rc = sqlite3_finalize(pStmt);

if( rc!=SQLITE_OK ){

goto end_deserialize;

}

p = memdbFromDbSchema(db, zSchema);

if( p==0 ){

rc = SQLITE_ERROR;

}else{

MemStore *pStore = p->pStore;

pStore->aData = pData;

pData = 0;

pStore->sz = szDb;

pStore->szAlloc = szBuf;

pStore->szMax = szBuf;

if( pStore->szMax<sqlite3GlobalConfig.mxMemdbSize ){

pStore->szMax = sqlite3GlobalConfig.mxMemdbSize;

}

pStore->mFlags = mFlags;

rc = SQLITE_OK;

}

end_deserialize:

if( pData && (mFlags & SQLITE_DESERIALIZE_FREEONCLOSE)!=0 ){

sqlite3_free(pData);

}

sqlite3_mutex_leave(db->mutex);

return rc;

}

** Return true if the VFS is the memvfs.

int sqlite3IsMemdb(const sqlite3_vfs *pVfs){

return pVfs==&memdb_vfs;

}

** This routine is called when the extension is loaded.

** Register the new VFS.

int sqlite3MemdbInit(void){

sqlite3_vfs *pLower = sqlite3_vfs_find(0);

unsigned int sz;

if( NEVER(pLower==0) ) return SQLITE_ERROR;

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_OMIT_DESERIALIZE */

sqlcipher/src/memdb.c at sqlite-release · sqlcipher/sqlcipher · GitHub

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