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Better handling for databases with corrupt headers.

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FossilOrigin-Name: 17f68d803685405d880025134c71bac01077962d677f2902a608952d0b9cdb5a
This commit is contained in:
dan
2022-10-04 19:43:12 +00:00
parent 7e33f8f43b
commit 041cc06139
3 changed files with 275 additions and 8 deletions
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269
ext/recover/sqlite3recover.c
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@ -28,6 +28,7 @@ __declspec(dllexport)
int sqlite3_dbdata_init(sqlite3*, char**, const sqlite3_api_routines*);
typedef unsigned int u32;
typedef unsigned char u8;
typedef sqlite3_int64 i64;
typedef struct RecoverTable RecoverTable;
@ -240,11 +241,30 @@ struct sqlite3_recover {
#define RECOVER_STATE_SCHEMA2 5
#define RECOVER_STATE_DONE 6
/*
** Global variables used by this extension.
*/
typedef struct RecoverGlobal RecoverGlobal;
struct RecoverGlobal {
const sqlite3_io_methods *pMethods;
};
static RecoverGlobal recover_g;
/*
** Use this static SQLite mutex to protect the globals during the
** first call to sqlite3_recover_step().
*/
#define RECOVER_MUTEX_ID SQLITE_MUTEX_STATIC_APP2
/*
** Default value for SQLITE_RECOVER_ROWIDS (sqlite3_recover.bRecoverRowid).
*/
#define RECOVER_ROWID_DEFAULT 1
/*
** Like strlen(). But handles NULL pointer arguments.
*/
@ -1840,6 +1860,247 @@ static void recoverFinalCleanup(sqlite3_recover *p){
p->dbOut = 0;
}
static int recoverVfsClose(sqlite3_file*);
static int recoverVfsRead(sqlite3_file*, void*, int iAmt, sqlite3_int64 iOfst);
static int recoverVfsWrite(sqlite3_file*, const void*, int, sqlite3_int64);
static int recoverVfsTruncate(sqlite3_file*, sqlite3_int64 size);
static int recoverVfsSync(sqlite3_file*, int flags);
static int recoverVfsFileSize(sqlite3_file*, sqlite3_int64 *pSize);
static int recoverVfsLock(sqlite3_file*, int);
static int recoverVfsUnlock(sqlite3_file*, int);
static int recoverVfsCheckReservedLock(sqlite3_file*, int *pResOut);
static int recoverVfsFileControl(sqlite3_file*, int op, void *pArg);
static int recoverVfsSectorSize(sqlite3_file*);
static int recoverVfsDeviceCharacteristics(sqlite3_file*);
static int recoverVfsShmMap(sqlite3_file*, int, int, int, void volatile**);
static int recoverVfsShmLock(sqlite3_file*, int offset, int n, int flags);
static void recoverVfsShmBarrier(sqlite3_file*);
static int recoverVfsShmUnmap(sqlite3_file*, int deleteFlag);
static sqlite3_io_methods recover_methods = {
2, /* iVersion */
recoverVfsClose,
recoverVfsRead,
recoverVfsWrite,
recoverVfsTruncate,
recoverVfsSync,
recoverVfsFileSize,
recoverVfsLock,
recoverVfsUnlock,
recoverVfsCheckReservedLock,
recoverVfsFileControl,
recoverVfsSectorSize,
recoverVfsDeviceCharacteristics,
recoverVfsShmMap,
recoverVfsShmLock,
recoverVfsShmBarrier,
recoverVfsShmUnmap,
0, 0
};
static int recoverVfsClose(sqlite3_file *pFd){
assert( pFd->pMethods!=&recover_methods );
return pFd->pMethods->xClose(pFd);
}
static u32 recoverGetU16(const u8 *a){
return (((u32)a[0])<<8) + ((u32)a[1]);
}
static u32 recoverGetU32(const u8 *a){
return (((u32)a[0])<<24) + (((u32)a[1])<<16) + (((u32)a[2])<<8) + ((u32)a[3]);
}
static void recoverPutU16(u8 *a, u32 v){
a[0] = (v>>8) & 0x00FF;
a[1] = (v>>0) & 0x00FF;
}
static u32 recoverPutU32(u8 *a, u32 v){
a[0] = (v>>24) & 0x00FF;
a[1] = (v>>16) & 0x00FF;
a[2] = (v>>8) & 0x00FF;
a[3] = (v>>0) & 0x00FF;
}
static int recoverVfsRead(sqlite3_file *pFd, void *aBuf, int nByte, i64 iOff){
int rc = SQLITE_OK;
if( pFd->pMethods==&recover_methods ){
pFd->pMethods = recover_g.pMethods;
rc = pFd->pMethods->xRead(pFd, aBuf, nByte, iOff);
if( rc==SQLITE_OK && iOff==0 && nByte>=100 ){
/* Ensure that the database has a valid header file. The only fields
** that really matter to recovery are:
**
** + Database page size (16-bits at offset 16)
** + Size of db in pages (32-bits at offset 28)
** + Database encoding (32-bits at offset 56)
**
** Also preserved are:
**
** + first freelist page (32-bits at offset 32)
** + size of freelist (32-bits at offset 36)
**
** We also try to preserve the auto-vacuum, incr-value, user-version
** and application-id fields - all 32 bit quantities at offsets
** 52, 60, 64 and 68. All other fields are set to known good values.
*/
const int aPreserve[] = {32, 36, 52, 60, 64, 68};
u8 aHdr[100] = {
0x53, 0x51, 0x4c, 0x69, 0x74, 0x65, 0x20, 0x66,
0x6f, 0x72, 0x6d, 0x61, 0x74, 0x20, 0x33, 0x00,
0xFF, 0xFF, 0x01, 0x01, 0x00, 0x40, 0x20, 0x20,
0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04,
0x00, 0x00, 0x10, 0x00, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x2e, 0x5b, 0x30
};
u8 *a = (u8*)aBuf;
u32 pgsz = recoverGetU16(&a[16]);
u32 enc = recoverGetU32(&a[56]);
u32 dbsz = 0;
i64 dbFileSize = 0;
int ii;
if( pgsz==0x01 ) pgsz = 65536;
rc = pFd->pMethods->xFileSize(pFd, &dbFileSize);
dbsz = dbFileSize / pgsz;
if( enc!=SQLITE_UTF8 && enc!=SQLITE_UTF16BE && enc!=SQLITE_UTF16LE ){
enc = SQLITE_UTF8;
}
recoverPutU32(&aHdr[28], dbsz);
recoverPutU32(&aHdr[56], enc);
if( pgsz==65536 ) pgsz = 1;
recoverPutU16(&aHdr[16], pgsz);
for(ii=0; ii<sizeof(aPreserve)/sizeof(aPreserve[0]); ii++){
memcpy(&aHdr[aPreserve[ii]], &a[aPreserve[ii]], 4);
}
memcpy(aBuf, aHdr, sizeof(aHdr));
}
pFd->pMethods = &recover_methods;
}else{
rc = pFd->pMethods->xRead(pFd, aBuf, nByte, iOff);
}
return rc;
}
#define RECOVER_VFS_WRAPPER(code) \
int rc = SQLITE_OK; \
if( pFd->pMethods==&recover_methods ){ \
pFd->pMethods = recover_g.pMethods; \
rc = code; \
pFd->pMethods = &recover_methods; \
}else{ \
rc = code; \
} \
return rc;
static int recoverVfsWrite(
sqlite3_file *pFd, const void *aBuf, int nByte, i64 iOff
){
RECOVER_VFS_WRAPPER (
pFd->pMethods->xWrite(pFd, aBuf, nByte, iOff)
);
}
static int recoverVfsTruncate(sqlite3_file *pFd, sqlite3_int64 size){
RECOVER_VFS_WRAPPER (
pFd->pMethods->xTruncate(pFd, size)
);
}
static int recoverVfsSync(sqlite3_file *pFd, int flags){
RECOVER_VFS_WRAPPER (
pFd->pMethods->xSync(pFd, flags)
);
}
static int recoverVfsFileSize(sqlite3_file *pFd, sqlite3_int64 *pSize){
RECOVER_VFS_WRAPPER (
pFd->pMethods->xFileSize(pFd, pSize)
);
}
static int recoverVfsLock(sqlite3_file *pFd, int eLock){
RECOVER_VFS_WRAPPER (
pFd->pMethods->xLock(pFd, eLock)
);
}
static int recoverVfsUnlock(sqlite3_file *pFd, int eLock){
RECOVER_VFS_WRAPPER (
pFd->pMethods->xUnlock(pFd, eLock)
);
}
static int recoverVfsCheckReservedLock(sqlite3_file *pFd, int *pResOut){
RECOVER_VFS_WRAPPER (
pFd->pMethods->xCheckReservedLock(pFd, pResOut)
);
}
static int recoverVfsFileControl(sqlite3_file *pFd, int op, void *pArg){
RECOVER_VFS_WRAPPER (
pFd->pMethods->xFileControl(pFd, op, pArg)
);
}
static int recoverVfsSectorSize(sqlite3_file *pFd){
RECOVER_VFS_WRAPPER (
pFd->pMethods->xSectorSize(pFd)
);
}
static int recoverVfsDeviceCharacteristics(sqlite3_file *pFd){
RECOVER_VFS_WRAPPER (
pFd->pMethods->xDeviceCharacteristics(pFd)
);
}
static int recoverVfsShmMap(
sqlite3_file *pFd, int iPg, int pgsz, int bExtend, void volatile **pp
){
RECOVER_VFS_WRAPPER (
pFd->pMethods->xShmMap(pFd, iPg, pgsz, bExtend, pp)
);
}
static int recoverVfsShmLock(sqlite3_file *pFd, int offset, int n, int flags){
RECOVER_VFS_WRAPPER (
pFd->pMethods->xShmLock(pFd, offset, n, flags)
);
}
static void recoverVfsShmBarrier(sqlite3_file *pFd){
if( pFd->pMethods==&recover_methods ){
pFd->pMethods = recover_g.pMethods;
pFd->pMethods->xShmBarrier(pFd);
pFd->pMethods = &recover_methods;
}else{
pFd->pMethods->xShmBarrier(pFd);
}
}
static int recoverVfsShmUnmap(sqlite3_file *pFd, int deleteFlag){
RECOVER_VFS_WRAPPER (
pFd->pMethods->xShmUnmap(pFd, deleteFlag)
);
}
static void recoverInstallWrapper(sqlite3_recover *p){
sqlite3_file *pFd = 0;
assert( recover_g.pMethods==0 );
sqlite3_file_control(p->dbIn, p->zDb, SQLITE_FCNTL_FILE_POINTER, (void*)&pFd);
if( pFd ){
recover_g.pMethods = pFd->pMethods;
pFd->pMethods = &recover_methods;
}
}
static void recoverUninstallWrapper(sqlite3_recover *p){
if( recover_g.pMethods ){
sqlite3_file *pFd = 0;
sqlite3_file_control(p->dbIn, p->zDb,SQLITE_FCNTL_FILE_POINTER,(void*)&pFd);
assert( pFd );
pFd->pMethods = recover_g.pMethods;
recover_g.pMethods = 0;
}
}
static void recoverStep(sqlite3_recover *p){
assert( p && p->errCode==SQLITE_OK );
switch( p->eState ){
@ -1853,6 +2114,9 @@ static void recoverStep(sqlite3_recover *p){
** user functions with the new handle. */
recoverOpenOutput(p);
sqlite3_mutex_enter( sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_APP2) );
recoverInstallWrapper(p);
/* Open transactions on both the input and output databases. */
recoverExec(p, p->dbIn, "PRAGMA writable_schema = on");
recoverExec(p, p->dbIn, "BEGIN");
@ -1860,8 +2124,11 @@ static void recoverStep(sqlite3_recover *p){
recoverExec(p, p->dbOut, "BEGIN");
recoverCacheSchema(p);
recoverWriteSchema1(p);
recoverUninstallWrapper(p);
sqlite3_mutex_leave( sqlite3_mutex_alloc(SQLITE_MUTEX_STATIC_APP2) );
recoverWriteSchema1(p);
p->eState = RECOVER_STATE_WRITING;
break;