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If SQLITE_USE_SEH is defined, handle structured-exceptions thrown by MSVC builds if the *-shm file mapping is accessed after it becomes invalid for some reason.

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FossilOrigin-Name: 5c5fa47076c5da25ca92248df3a4c11b90a0225a07f05d7220fa95d9bbb36f43
This commit is contained in:
dan
2021-08-19 21:01:15 +00:00
parent fd46ec6476
commit 8aa22ffe98
5 changed files with 451 additions and 126 deletions
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448
src/wal.c
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@@ -528,6 +528,13 @@ struct Wal {
u32 iReCksum; /* On commit, recalculate checksums from here */
const char *zWalName; /* Name of WAL file */
u32 nCkpt; /* Checkpoint sequence counter in the wal-header */
#ifdef SQLITE_USE_SEH
# ifdef SQLITE_DEBUG
int nSehTry; /* Number of nested SEH_TRY{} blocks */
# endif
u32 lockMask; /* Mask of locks held */
void *pFree; /* Pointer to sqlite3_free() if exception thrown */
#endif
#ifdef SQLITE_DEBUG
u8 lockError; /* True if a locking error has occurred */
#endif
@@ -610,6 +617,46 @@ struct WalIterator {
sizeof(ht_slot)*HASHTABLE_NSLOT + HASHTABLE_NPAGE*sizeof(u32) \
)
#ifdef SQLITE_USE_SEH
#include <Windows.h>
# define SEH_TRY __try { \
assert( walAssertLockmask(pWal) && pWal->nSehTry==0 ); TESTONLY(pWal->nSehTry++);
# define SEH_EXCEPT TESTONLY(pWal->nSehTry--); assert( pWal->nSehTry==0 ); \
} __except( sehExceptionFilter(pWal, GetExceptionCode()) )
# define SEH_INJECT_FAULT sehInjectFault(pWal)
/*
** The second argument is the return value of GetExceptionCode() for the
** current exception. Return EXCEPTION_EXECUTE_HANDLER if the exception code
** indicates that the exception may have been caused by accessing the *-shm
** file mapping. Or EXCEPTION_CONTINUE_SEARCH otherwise.
*/
static int sehExceptionFilter(Wal *pWal, int eCode){
TESTONLY(pWal->nSehTry--);
if( eCode==EXCEPTION_ACCESS_VIOLATION ){
return EXCEPTION_EXECUTE_HANDLER;
}
return EXCEPTION_CONTINUE_SEARCH;
}
static void sehInjectFault(Wal *pWal){
assert( pWal->nSehTry>0 );
if( sqlite3FaultSim(650) ){
RaiseException(EXCEPTION_ACCESS_VIOLATION, 0, 0, NULL);
}
}
#else
# define SEH_TRY
# define SEH_EXCEPT if(0)
# define SEH_INJECT_FAULT
#endif /* ifdef SQLITE_USE_SEH */
/*
** Obtain a pointer to the iPage'th page of the wal-index. The wal-index
** is broken into pages of WALINDEX_PGSZ bytes. Wal-index pages are
@@ -676,6 +723,7 @@ static int walIndexPage(
int iPage, /* The page we seek */
volatile u32 **ppPage /* Write the page pointer here */
){
SEH_INJECT_FAULT;
if( pWal->nWiData<=iPage || (*ppPage = pWal->apWiData[iPage])==0 ){
return walIndexPageRealloc(pWal, iPage, ppPage);
}
@@ -687,6 +735,7 @@ static int walIndexPage(
*/
static volatile WalCkptInfo *walCkptInfo(Wal *pWal){
assert( pWal->nWiData>0 && pWal->apWiData[0] );
SEH_INJECT_FAULT;
return (volatile WalCkptInfo*)&(pWal->apWiData[0][sizeof(WalIndexHdr)/2]);
}
@@ -695,6 +744,7 @@ static volatile WalCkptInfo *walCkptInfo(Wal *pWal){
*/
static volatile WalIndexHdr *walIndexHdr(Wal *pWal){
assert( pWal->nWiData>0 && pWal->apWiData[0] );
SEH_INJECT_FAULT;
return (volatile WalIndexHdr*)pWal->apWiData[0];
}
@@ -931,12 +981,18 @@ static int walLockShared(Wal *pWal, int lockIdx){
WALTRACE(("WAL%p: acquire SHARED-%s %s\n", pWal,
walLockName(lockIdx), rc ? "failed" : "ok"));
VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && (rc&0xFF)!=SQLITE_BUSY); )
#ifdef SQLITE_USE_SEH
if( rc==SQLITE_OK ) pWal->lockMask |= (1 << lockIdx);
#endif
return rc;
}
static void walUnlockShared(Wal *pWal, int lockIdx){
if( pWal->exclusiveMode ) return;
(void)sqlite3OsShmLock(pWal->pDbFd, lockIdx, 1,
SQLITE_SHM_UNLOCK | SQLITE_SHM_SHARED);
#ifdef SQLITE_USE_SEH
pWal->lockMask &= ~(1 << lockIdx);
#endif
WALTRACE(("WAL%p: release SHARED-%s\n", pWal, walLockName(lockIdx)));
}
static int walLockExclusive(Wal *pWal, int lockIdx, int n){
@@ -947,12 +1003,20 @@ static int walLockExclusive(Wal *pWal, int lockIdx, int n){
WALTRACE(("WAL%p: acquire EXCLUSIVE-%s cnt=%d %s\n", pWal,
walLockName(lockIdx), n, rc ? "failed" : "ok"));
VVA_ONLY( pWal->lockError = (u8)(rc!=SQLITE_OK && (rc&0xFF)!=SQLITE_BUSY); )
#ifdef SQLITE_USE_SEH
if( rc==SQLITE_OK ){
pWal->lockMask |= (((1<<n)-1) << (SQLITE_SHM_NLOCK+lockIdx));
}
#endif
return rc;
}
static void walUnlockExclusive(Wal *pWal, int lockIdx, int n){
if( pWal->exclusiveMode ) return;
(void)sqlite3OsShmLock(pWal->pDbFd, lockIdx, n,
SQLITE_SHM_UNLOCK | SQLITE_SHM_EXCLUSIVE);
#ifdef SQLITE_USE_SEH
pWal->lockMask &= ~(((1<<n)-1) << (SQLITE_SHM_NLOCK+lockIdx));
#endif
WALTRACE(("WAL%p: release EXCLUSIVE-%s cnt=%d\n", pWal,
walLockName(lockIdx), n));
}
@@ -1301,7 +1365,7 @@ static int walIndexRecover(Wal *pWal){
/* Malloc a buffer to read frames into. */
szFrame = szPage + WAL_FRAME_HDRSIZE;
aFrame = (u8 *)sqlite3_malloc64(szFrame + WALINDEX_PGSZ);
pWal->pFree = aFrame = (u8 *)sqlite3_malloc64(szFrame + WALINDEX_PGSZ);
if( !aFrame ){
rc = SQLITE_NOMEM_BKPT;
goto recovery_error;
@@ -1380,6 +1444,7 @@ static int walIndexRecover(Wal *pWal){
}
sqlite3_free(aFrame);
pWal->pFree = 0;
}
finished:
@@ -1789,22 +1854,16 @@ static int walIteratorInit(Wal *pWal, u32 nBackfill, WalIterator **pp){
nByte = sizeof(WalIterator)
+ (nSegment-1)*sizeof(struct WalSegment)
+ iLast*sizeof(ht_slot);
p = (WalIterator *)sqlite3_malloc64(nByte);
p = (WalIterator *)sqlite3_malloc64(nByte
+ sizeof(ht_slot) * (iLast>HASHTABLE_NPAGE?HASHTABLE_NPAGE:iLast)
);
if( !p ){
return SQLITE_NOMEM_BKPT;
}
memset(p, 0, nByte);
p->nSegment = nSegment;
/* Allocate temporary space used by the merge-sort routine. This block
** of memory will be freed before this function returns.
*/
aTmp = (ht_slot *)sqlite3_malloc64(
sizeof(ht_slot) * (iLast>HASHTABLE_NPAGE?HASHTABLE_NPAGE:iLast)
);
if( !aTmp ){
rc = SQLITE_NOMEM_BKPT;
}
aTmp = (ht_slot*)&(((u8*)p)[nByte]);
pWal->pFree = p;
for(i=walFramePage(nBackfill+1); rc==SQLITE_OK && i<nSegment; i++){
WalHashLoc sLoc;
@@ -1834,11 +1893,10 @@ static int walIteratorInit(Wal *pWal, u32 nBackfill, WalIterator **pp){
p->aSegment[i].aPgno = (u32 *)sLoc.aPgno;
}
}
sqlite3_free(aTmp);
if( rc!=SQLITE_OK ){
walIteratorFree(p);
p = 0;
pWal->pFree = p = 0;
}
*pp = p;
return rc;
@@ -2062,7 +2120,7 @@ static int walCheckpoint(
mxSafeFrame = pWal->hdr.mxFrame;
mxPage = pWal->hdr.nPage;
for(i=1; i<WAL_NREADER; i++){
u32 y = AtomicLoad(pInfo->aReadMark+i);
u32 y = AtomicLoad(pInfo->aReadMark+i); SEH_INJECT_FAULT;
if( mxSafeFrame>y ){
assert( y<=pWal->hdr.mxFrame );
rc = walBusyLock(pWal, xBusy, pBusyArg, WAL_READ_LOCK(i), 1);
@@ -2089,8 +2147,7 @@ static int walCheckpoint(
&& (rc = walBusyLock(pWal,xBusy,pBusyArg,WAL_READ_LOCK(0),1))==SQLITE_OK
){
u32 nBackfill = pInfo->nBackfill;
pInfo->nBackfillAttempted = mxSafeFrame;
pInfo->nBackfillAttempted = mxSafeFrame; SEH_INJECT_FAULT;
/* Sync the WAL to disk */
rc = sqlite3OsSync(pWal->pWalFd, CKPT_SYNC_FLAGS(sync_flags));
@@ -2172,6 +2229,7 @@ static int walCheckpoint(
*/
if( rc==SQLITE_OK && eMode!=SQLITE_CHECKPOINT_PASSIVE ){
assert( pWal->writeLock );
SEH_INJECT_FAULT;
if( pInfo->nBackfill<pWal->hdr.mxFrame ){
rc = SQLITE_BUSY;
}else if( eMode>=SQLITE_CHECKPOINT_RESTART ){
@@ -2203,7 +2261,9 @@ static int walCheckpoint(
}
walcheckpoint_out:
assert( pWal->pFree==(void*)pIter );
walIteratorFree(pIter);
pWal->pFree = 0;
return rc;
}
@@ -2239,6 +2299,10 @@ int sqlite3WalClose(
if( pWal ){
int isDelete = 0; /* True to unlink wal and wal-index files */
#ifdef SQLITE_USE_SEH
assert( pWal->lockMask==0 );
#endif
/* If an EXCLUSIVE lock can be obtained on the database file (using the
** ordinary, rollback-mode locking methods, this guarantees that the
** connection associated with this log file is the only connection to
@@ -2779,6 +2843,7 @@ static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
assert( pWal->nWiData>0 );
assert( pWal->apWiData[0]!=0 );
pInfo = walCkptInfo(pWal);
SEH_INJECT_FAULT;
if( !useWal && AtomicLoad(&pInfo->nBackfill)==pWal->hdr.mxFrame
#ifdef SQLITE_ENABLE_SNAPSHOT
&& (pWal->pSnapshot==0 || pWal->hdr.mxFrame==0)
@@ -2828,7 +2893,7 @@ static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
}
#endif
for(i=1; i<WAL_NREADER; i++){
u32 thisMark = AtomicLoad(pInfo->aReadMark+i);
u32 thisMark = AtomicLoad(pInfo->aReadMark+i); SEH_INJECT_FAULT;
if( mxReadMark<=thisMark && thisMark<=mxFrame ){
assert( thisMark!=READMARK_NOT_USED );
mxReadMark = thisMark;
@@ -2894,7 +2959,7 @@ static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
** we can guarantee that the checkpointer that set nBackfill could not
** see any pages past pWal->hdr.mxFrame, this problem does not come up.
*/
pWal->minFrame = AtomicLoad(&pInfo->nBackfill)+1;
pWal->minFrame = AtomicLoad(&pInfo->nBackfill)+1; SEH_INJECT_FAULT;
walShmBarrier(pWal);
if( AtomicLoad(pInfo->aReadMark+mxI)!=mxReadMark
|| memcmp((void *)walIndexHdr(pWal), &pWal->hdr, sizeof(WalIndexHdr))
@@ -2908,7 +2973,112 @@ static int walTryBeginRead(Wal *pWal, int *pChanged, int useWal, int cnt){
return rc;
}
#ifdef SQLITE_USE_SEH
/*
** This is the "standard" exception handler used in a few places to handle
** an exception thrown by reading from the *-shm mapping after it has become
** invalid in SQLITE_USE_SEH builds. It is used as follows:
**
** SEH_TRY { ... }
** SEH_EXCEPT { rc = walHandleException(pWal); }
**
** This function does three things:
**
** 1) Determines the locks that should be held, based on the contents of
** the Wal.readLock, Wal.writeLock and Wal.ckptLock variables. All other
** held locks are assumed to be transient locks that would have been
** released had the exception not been thrown and are dropped.
**
** 2) Frees the pointer at Wal.pFree, if any, using sqlite3_free().
**
** 3) Returns SQLITE_IOERR.
*/
static int walHandleException(Wal *pWal){
if( pWal->exclusiveMode==0 ){
static const int S = 1;
static const int E = (1<<SQLITE_SHM_NLOCK);
int ii;
u32 mUnlock = pWal->lockMask & ~(
(pWal->readLock<0 ? 0 : (S << WAL_READ_LOCK(pWal->readLock)))
| (pWal->writeLock ? (E << WAL_WRITE_LOCK) : 0)
| (pWal->ckptLock ? (E << WAL_CKPT_LOCK) : 0)
);
for(ii=0; ii<SQLITE_SHM_NLOCK; ii++){
if( (S<<ii) & mUnlock ) walUnlockShared(pWal, ii);
if( (E<<ii) & mUnlock ) walUnlockExclusive(pWal, ii, 1);
}
}
sqlite3_free(pWal->pFree);
pWal->pFree = 0;
return SQLITE_IOERR;
}
static int walAssertLockmask(Wal *pWal){
if( pWal->exclusiveMode==0 ){
static const int S = 1;
static const int E = (1<<SQLITE_SHM_NLOCK);
u32 mExpect = (
(pWal->readLock<0 ? 0 : (S << WAL_READ_LOCK(pWal->readLock)))
| (pWal->writeLock ? (E << WAL_WRITE_LOCK) : 0)
| (pWal->ckptLock ? (E << WAL_CKPT_LOCK) : 0)
#ifdef SQLITE_ENABLE_SNAPSHOT
| (pWal->pSnapshot ? (pWal->lockMask & (1 << WAL_CKPT_LOCK)) : 0)
#endif
);
assert( mExpect==pWal->lockMask );
}
return 1;
}
#endif
#ifdef SQLITE_ENABLE_SNAPSHOT
/*
** This function does the work of sqlite3WalSnapshotRecover().
*/
static int walSnapshotRecover(
Wal *pWal, /* WAL handle */
void *pBuf1, /* Temp buffer pWal->szPage bytes in size */
void *pBuf2 /* Temp buffer pWal->szPage bytes in size */
){
int szPage = (int)pWal->szPage;
int rc;
i64 szDb; /* Size of db file in bytes */
rc = sqlite3OsFileSize(pWal->pDbFd, &szDb);
if( rc==SQLITE_OK ){
volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
u32 i = pInfo->nBackfillAttempted;
for(i=pInfo->nBackfillAttempted; i>AtomicLoad(&pInfo->nBackfill); i--){
WalHashLoc sLoc; /* Hash table location */
u32 pgno; /* Page number in db file */
i64 iDbOff; /* Offset of db file entry */
i64 iWalOff; /* Offset of wal file entry */
rc = walHashGet(pWal, walFramePage(i), &sLoc);
if( rc!=SQLITE_OK ) break;
pgno = sLoc.aPgno[i-sLoc.iZero];
iDbOff = (i64)(pgno-1) * szPage;
if( iDbOff+szPage<=szDb ){
iWalOff = walFrameOffset(i, szPage) + WAL_FRAME_HDRSIZE;
rc = sqlite3OsRead(pWal->pWalFd, pBuf1, szPage, iWalOff);
if( rc==SQLITE_OK ){
rc = sqlite3OsRead(pWal->pDbFd, pBuf2, szPage, iDbOff);
}
if( rc!=SQLITE_OK || 0==memcmp(pBuf1, pBuf2, szPage) ){
break;
}
}
pInfo->nBackfillAttempted = i-1;
}
}
return rc;
}
/*
** Attempt to reduce the value of the WalCkptInfo.nBackfillAttempted
** variable so that older snapshots can be accessed. To do this, loop
@@ -2934,49 +3104,23 @@ int sqlite3WalSnapshotRecover(Wal *pWal){
assert( pWal->readLock>=0 );
rc = walLockExclusive(pWal, WAL_CKPT_LOCK, 1);
if( rc==SQLITE_OK ){
volatile WalCkptInfo *pInfo = walCkptInfo(pWal);
int szPage = (int)pWal->szPage;
i64 szDb; /* Size of db file in bytes */
rc = sqlite3OsFileSize(pWal->pDbFd, &szDb);
if( rc==SQLITE_OK ){
void *pBuf1 = sqlite3_malloc(szPage);
void *pBuf2 = sqlite3_malloc(szPage);
if( pBuf1==0 || pBuf2==0 ){
rc = SQLITE_NOMEM;
}else{
u32 i = pInfo->nBackfillAttempted;
for(i=pInfo->nBackfillAttempted; i>AtomicLoad(&pInfo->nBackfill); i--){
WalHashLoc sLoc; /* Hash table location */
u32 pgno; /* Page number in db file */
i64 iDbOff; /* Offset of db file entry */
i64 iWalOff; /* Offset of wal file entry */
rc = walHashGet(pWal, walFramePage(i), &sLoc);
if( rc!=SQLITE_OK ) break;
pgno = sLoc.aPgno[i-sLoc.iZero];
iDbOff = (i64)(pgno-1) * szPage;
if( iDbOff+szPage<=szDb ){
iWalOff = walFrameOffset(i, szPage) + WAL_FRAME_HDRSIZE;
rc = sqlite3OsRead(pWal->pWalFd, pBuf1, szPage, iWalOff);
if( rc==SQLITE_OK ){
rc = sqlite3OsRead(pWal->pDbFd, pBuf2, szPage, iDbOff);
}
if( rc!=SQLITE_OK || 0==memcmp(pBuf1, pBuf2, szPage) ){
break;
}
}
pInfo->nBackfillAttempted = i-1;
}
void *pBuf1 = sqlite3_malloc(pWal->szPage);
void *pBuf2 = sqlite3_malloc(pWal->szPage);
if( pBuf1==0 || pBuf2==0 ){
rc = SQLITE_NOMEM;
}else{
pWal->ckptLock = 1;
SEH_TRY {
rc = walSnapshotRecover(pWal, pBuf1, pBuf2);
}
sqlite3_free(pBuf1);
sqlite3_free(pBuf2);
SEH_EXCEPT {
rc = SQLITE_IOERR;
}
pWal->ckptLock = 0;
}
sqlite3_free(pBuf1);
sqlite3_free(pBuf2);
walUnlockExclusive(pWal, WAL_CKPT_LOCK, 1);
}
@@ -2998,10 +3142,11 @@ int sqlite3WalSnapshotRecover(Wal *pWal){
** Pager layer will use this to know that its cache is stale and
** needs to be flushed.
*/
int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
static int walBeginReadTransaction(Wal *pWal, int *pChanged){
int rc; /* Return code */
int cnt = 0; /* Number of TryBeginRead attempts */
#ifdef SQLITE_ENABLE_SNAPSHOT
int ckptLock = 0;
int bChanged = 0;
WalIndexHdr *pSnapshot = pWal->pSnapshot;
#endif
@@ -3029,7 +3174,7 @@ int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
if( rc!=SQLITE_OK ){
return rc;
}
pWal->ckptLock = 1;
ckptLock = 1;
}
#endif
@@ -3093,15 +3238,25 @@ int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
}
/* Release the shared CKPT lock obtained above. */
if( pWal->ckptLock ){
if( ckptLock ){
assert( pSnapshot );
walUnlockShared(pWal, WAL_CKPT_LOCK);
pWal->ckptLock = 0;
}
#endif
return rc;
}
int sqlite3WalBeginReadTransaction(Wal *pWal, int *pChanged){
int rc;
SEH_TRY {
rc = walBeginReadTransaction(pWal, pChanged);
}
SEH_EXCEPT {
rc = walHandleException(pWal);
}
return rc;
}
/*
** Finish with a read transaction. All this does is release the
** read-lock.
@@ -3122,7 +3277,7 @@ void sqlite3WalEndReadTransaction(Wal *pWal){
** Return SQLITE_OK if successful, or an error code if an error occurs. If an
** error does occur, the final value of *piRead is undefined.
*/
int sqlite3WalFindFrame(
static int walFindFrame(
Wal *pWal, /* WAL handle */
Pgno pgno, /* Database page number to read data for */
u32 *piRead /* OUT: Frame number (or zero) */
@@ -3185,6 +3340,7 @@ int sqlite3WalFindFrame(
}
nCollide = HASHTABLE_NSLOT;
iKey = walHash(pgno);
SEH_INJECT_FAULT;
while( (iH = AtomicLoad(&sLoc.aHash[iKey]))!=0 ){
u32 iFrame = iH + sLoc.iZero;
if( iFrame<=iLast && iFrame>=pWal->minFrame && sLoc.aPgno[iH]==pgno ){
@@ -3221,6 +3377,19 @@ int sqlite3WalFindFrame(
return SQLITE_OK;
}
int sqlite3WalFindFrame(
Wal *pWal, /* WAL handle */
Pgno pgno, /* Database page number to read data for */
u32 *piRead /* OUT: Frame number (or zero) */
){
int rc;
SEH_TRY {
rc = walFindFrame(pWal, pgno, piRead);
}
SEH_EXCEPT { rc = SQLITE_IOERR; }
return rc;
}
/*
** Read the contents of frame iRead from the wal file into buffer pOut
** (which is nOut bytes in size). Return SQLITE_OK if successful, or an
@@ -3302,12 +3471,17 @@ int sqlite3WalBeginWriteTransaction(Wal *pWal){
** time the read transaction on this connection was started, then
** the write is disallowed.
*/
if( memcmp(&pWal->hdr, (void *)walIndexHdr(pWal), sizeof(WalIndexHdr))!=0 ){
SEH_TRY {
if( memcmp(&pWal->hdr, (void *)walIndexHdr(pWal), sizeof(WalIndexHdr))!=0 ){
rc = SQLITE_BUSY_SNAPSHOT;
}
}
SEH_EXCEPT { rc = SQLITE_IOERR; }
if( rc!=SQLITE_OK ){
walUnlockExclusive(pWal, WAL_WRITE_LOCK, 1);
pWal->writeLock = 0;
rc = SQLITE_BUSY_SNAPSHOT;
}
return rc;
}
@@ -3343,30 +3517,35 @@ int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx){
Pgno iMax = pWal->hdr.mxFrame;
Pgno iFrame;
/* Restore the clients cache of the wal-index header to the state it
** was in before the client began writing to the database.
*/
memcpy(&pWal->hdr, (void *)walIndexHdr(pWal), sizeof(WalIndexHdr));
for(iFrame=pWal->hdr.mxFrame+1;
ALWAYS(rc==SQLITE_OK) && iFrame<=iMax;
iFrame++
){
/* This call cannot fail. Unless the page for which the page number
** is passed as the second argument is (a) in the cache and
** (b) has an outstanding reference, then xUndo is either a no-op
** (if (a) is false) or simply expels the page from the cache (if (b)
** is false).
**
** If the upper layer is doing a rollback, it is guaranteed that there
** are no outstanding references to any page other than page 1. And
** page 1 is never written to the log until the transaction is
** committed. As a result, the call to xUndo may not fail.
SEH_TRY {
/* Restore the clients cache of the wal-index header to the state it
** was in before the client began writing to the database.
*/
assert( walFramePgno(pWal, iFrame)!=1 );
rc = xUndo(pUndoCtx, walFramePgno(pWal, iFrame));
memcpy(&pWal->hdr, (void *)walIndexHdr(pWal), sizeof(WalIndexHdr));
for(iFrame=pWal->hdr.mxFrame+1;
ALWAYS(rc==SQLITE_OK) && iFrame<=iMax;
iFrame++
){
/* This call cannot fail. Unless the page for which the page number
** is passed as the second argument is (a) in the cache and
** (b) has an outstanding reference, then xUndo is either a no-op
** (if (a) is false) or simply expels the page from the cache (if (b)
** is false).
**
** If the upper layer is doing a rollback, it is guaranteed that there
** are no outstanding references to any page other than page 1. And
** page 1 is never written to the log until the transaction is
** committed. As a result, the call to xUndo may not fail.
*/
assert( walFramePgno(pWal, iFrame)!=1 );
rc = xUndo(pUndoCtx, walFramePgno(pWal, iFrame));
}
if( iMax!=pWal->hdr.mxFrame ) walCleanupHash(pWal);
}
SEH_EXCEPT {
rc = SQLITE_IOERR;
}
if( iMax!=pWal->hdr.mxFrame ) walCleanupHash(pWal);
}
return rc;
}
@@ -3410,7 +3589,12 @@ int sqlite3WalSavepointUndo(Wal *pWal, u32 *aWalData){
pWal->hdr.mxFrame = aWalData[0];
pWal->hdr.aFrameCksum[0] = aWalData[1];
pWal->hdr.aFrameCksum[1] = aWalData[2];
walCleanupHash(pWal);
SEH_TRY {
walCleanupHash(pWal);
}
SEH_EXCEPT {
rc = SQLITE_IOERR;
}
}
return rc;
@@ -3591,7 +3775,7 @@ static int walRewriteChecksums(Wal *pWal, u32 iLast){
** Write a set of frames to the log. The caller must hold the write-lock
** on the log file (obtained using sqlite3WalBeginWriteTransaction()).
*/
int sqlite3WalFrames(
static int walFrames(
Wal *pWal, /* Wal handle to write to */
int szPage, /* Database page-size in bytes */
PgHdr *pList, /* List of dirty pages to write */
@@ -3700,7 +3884,7 @@ int sqlite3WalFrames(
** checksums must be recomputed when the transaction is committed. */
if( iFirst && (p->pDirty || isCommit==0) ){
u32 iWrite = 0;
VVA_ONLY(rc =) sqlite3WalFindFrame(pWal, p->pgno, &iWrite);
VVA_ONLY(rc =) walFindFrame(pWal, p->pgno, &iWrite);
assert( rc==SQLITE_OK || iWrite==0 );
if( iWrite>=iFirst ){
i64 iOff = walFrameOffset(iWrite, szPage) + WAL_FRAME_HDRSIZE;
@@ -3819,6 +4003,24 @@ int sqlite3WalFrames(
return rc;
}
int sqlite3WalFrames(
Wal *pWal, /* Wal handle to write to */
int szPage, /* Database page-size in bytes */
PgHdr *pList, /* List of dirty pages to write */
Pgno nTruncate, /* Database size after this commit */
int isCommit, /* True if this is a commit */
int sync_flags /* Flags to pass to OsSync() (or 0) */
){
int rc;
SEH_TRY {
rc = walFrames(pWal, szPage, pList, nTruncate, isCommit, sync_flags);
}
SEH_EXCEPT {
rc = walHandleException(pWal);
}
return rc;
}
/*
** This routine is called to implement sqlite3_wal_checkpoint() and
** related interfaces.
@@ -3848,6 +4050,7 @@ int sqlite3WalCheckpoint(
assert( pWal->ckptLock==0 );
assert( pWal->writeLock==0 );
assert( pWal->readLock<0 );
/* EVIDENCE-OF: R-62920-47450 The busy-handler callback is never invoked
** in the SQLITE_CHECKPOINT_PASSIVE mode. */
@@ -3898,30 +4101,34 @@ int sqlite3WalCheckpoint(
/* Read the wal-index header. */
if( rc==SQLITE_OK ){
walDisableBlocking(pWal);
rc = walIndexReadHdr(pWal, &isChanged);
(void)walEnableBlocking(pWal);
if( isChanged && pWal->pDbFd->pMethods->iVersion>=3 ){
sqlite3OsUnfetch(pWal->pDbFd, 0, 0);
SEH_TRY {
if( rc==SQLITE_OK ){
walDisableBlocking(pWal);
rc = walIndexReadHdr(pWal, &isChanged);
(void)walEnableBlocking(pWal);
if( isChanged && pWal->pDbFd->pMethods->iVersion>=3 ){
sqlite3OsUnfetch(pWal->pDbFd, 0, 0);
}
}
}
/* Copy data from the log to the database file. */
if( rc==SQLITE_OK ){
if( pWal->hdr.mxFrame && walPagesize(pWal)!=nBuf ){
rc = SQLITE_CORRUPT_BKPT;
}else{
rc = walCheckpoint(pWal, db, eMode2, xBusy2, pBusyArg, sync_flags, zBuf);
/* Copy data from the log to the database file. */
if( rc==SQLITE_OK ){
if( pWal->hdr.mxFrame && walPagesize(pWal)!=nBuf ){
rc = SQLITE_CORRUPT_BKPT;
}else{
rc = walCheckpoint(pWal, db, eMode2, xBusy2, pBusyArg, sync_flags, zBuf);
}
}
/* If no error occurred, set the output variables. */
if( rc==SQLITE_OK || rc==SQLITE_BUSY ){
if( pnLog ) *pnLog = (int)pWal->hdr.mxFrame;
if( pnCkpt ) *pnCkpt = (int)(walCkptInfo(pWal)->nBackfill);
}
}
SEH_EXCEPT {
rc = walHandleException(pWal);
}
if( isChanged ){
/* If a new wal-index header was loaded before the checkpoint was
@@ -3998,7 +4205,9 @@ int sqlite3WalExclusiveMode(Wal *pWal, int op){
** locks are taken in this case). Nor should the pager attempt to
** upgrade to exclusive-mode following such an error.
*/
#ifndef SQLITE_USE_SEH
assert( pWal->readLock>=0 || pWal->lockError );
#endif
assert( pWal->readLock>=0 || (op<=0 && pWal->exclusiveMode==0) );
if( op==0 ){
@@ -4099,16 +4308,21 @@ int sqlite3_snapshot_cmp(sqlite3_snapshot *p1, sqlite3_snapshot *p2){
*/
int sqlite3WalSnapshotCheck(Wal *pWal, sqlite3_snapshot *pSnapshot){
int rc;
rc = walLockShared(pWal, WAL_CKPT_LOCK);
if( rc==SQLITE_OK ){
WalIndexHdr *pNew = (WalIndexHdr*)pSnapshot;
if( memcmp(pNew->aSalt, pWal->hdr.aSalt, sizeof(pWal->hdr.aSalt))
|| pNew->mxFrame<walCkptInfo(pWal)->nBackfillAttempted
){
rc = SQLITE_ERROR_SNAPSHOT;
walUnlockShared(pWal, WAL_CKPT_LOCK);
SEH_TRY {
rc = walLockShared(pWal, WAL_CKPT_LOCK);
if( rc==SQLITE_OK ){
WalIndexHdr *pNew = (WalIndexHdr*)pSnapshot;
if( memcmp(pNew->aSalt, pWal->hdr.aSalt, sizeof(pWal->hdr.aSalt))
|| pNew->mxFrame<walCkptInfo(pWal)->nBackfillAttempted
){
rc = SQLITE_ERROR_SNAPSHOT;
walUnlockShared(pWal, WAL_CKPT_LOCK);
}
}
}
SEH_EXCEPT {
rc = walHandleException(pWal);
}
return rc;
}