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Change the checksum used in WAL files so that each frames checksum depends on the content of the WAL header and all frame headers and content up to and including the frame to which the checksum is attached.

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FossilOrigin-Name: 8a53f12c83a107684b99f4a9de371b5ea3ca810a
This commit is contained in:
dan
2010-05-24 13:57:42 +00:00
parent c81791573a
commit 71d8991932
8 changed files with 146 additions and 81 deletions
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78
src/wal.c
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@@ -214,13 +214,14 @@ typedef struct WalIterator WalIterator;
** object.
*/
struct WalIndexHdr {
u32 iChange; /* Counter incremented each transaction */
u16 bigEndCksum; /* True if checksums in WAL are big-endian */
u16 szPage; /* Database page size in bytes */
u32 mxFrame; /* Index of last valid frame in the WAL */
u32 nPage; /* Size of database in pages */
u32 aSalt[2]; /* Salt-1 and salt-2 values copied from WAL header */
u32 aCksum[2]; /* Checksum over all prior fields */
u32 iChange; /* Counter incremented each transaction */
u16 bigEndCksum; /* True if checksums in WAL are big-endian */
u16 szPage; /* Database page size in bytes */
u32 mxFrame; /* Index of last valid frame in the WAL */
u32 nPage; /* Size of database in pages */
u32 aFrameCksum[2]; /* Checksum of last frame in log */
u32 aSalt[2]; /* Two salt values copied from WAL header */
u32 aCksum[2]; /* Checksum over all prior fields */
};
/* A block of WALINDEX_LOCK_RESERVED bytes beginning at
@@ -424,14 +425,14 @@ static void walEncodeFrame(
u8 *aFrame /* OUT: Write encoded frame here */
){
int nativeCksum; /* True for native byte-order checksums */
u32 aCksum[2];
u32 *aCksum = pWal->hdr.aFrameCksum;
assert( WAL_FRAME_HDRSIZE==24 );
sqlite3Put4byte(&aFrame[0], iPage);
sqlite3Put4byte(&aFrame[4], nTruncate);
memcpy(&aFrame[8], pWal->hdr.aSalt, 8);
nativeCksum = (pWal->hdr.bigEndCksum==SQLITE_BIGENDIAN);
walChecksumBytes(nativeCksum, aFrame, 16, 0, aCksum);
walChecksumBytes(nativeCksum, aFrame, 8, aCksum, aCksum);
walChecksumBytes(nativeCksum, aData, pWal->szPage, aCksum, aCksum);
sqlite3Put4byte(&aFrame[16], aCksum[0]);
@@ -451,8 +452,8 @@ static int walDecodeFrame(
u8 *aFrame /* Frame data */
){
int nativeCksum; /* True for native byte-order checksums */
u32 *aCksum = pWal->hdr.aFrameCksum;
u32 pgno; /* Page number of the frame */
u32 aCksum[2];
assert( WAL_FRAME_HDRSIZE==24 );
/* A frame is only valid if the salt values in the frame-header
@@ -474,7 +475,7 @@ static int walDecodeFrame(
** the checksum in the last 8 bytes of the frame-header.
*/
nativeCksum = (pWal->hdr.bigEndCksum==SQLITE_BIGENDIAN);
walChecksumBytes(nativeCksum, aFrame, 16, 0, aCksum);
walChecksumBytes(nativeCksum, aFrame, 8, aCksum, aCksum);
walChecksumBytes(nativeCksum, aData, pWal->szPage, aCksum, aCksum);
if( aCksum[0]!=sqlite3Get4byte(&aFrame[16])
|| aCksum[1]!=sqlite3Get4byte(&aFrame[20])
@@ -739,10 +740,10 @@ static int walIndexAppend(Wal *pWal, u32 iFrame, u32 iPage){
static int walIndexRecover(Wal *pWal){
int rc; /* Return Code */
i64 nSize; /* Size of log file */
WalIndexHdr hdr; /* Recovered wal-index header */
u32 aFrameCksum[2] = {0, 0};
assert( pWal->lockState>SQLITE_SHM_READ );
memset(&hdr, 0, sizeof(hdr));
memset(&pWal->hdr, 0, sizeof(WalIndexHdr));
rc = sqlite3OsFileSize(pWal->pWalFd, &nSize);
if( rc!=SQLITE_OK ){
@@ -779,10 +780,13 @@ static int walIndexRecover(Wal *pWal){
){
goto finished;
}
hdr.bigEndCksum = pWal->hdr.bigEndCksum = (magic&0x00000001);
pWal->hdr.bigEndCksum = (magic&0x00000001);
pWal->szPage = szPage;
pWal->nCkpt = sqlite3Get4byte(&aBuf[12]);
memcpy(&pWal->hdr.aSalt, &aBuf[16], 8);
walChecksumBytes(pWal->hdr.bigEndCksum==SQLITE_BIGENDIAN,
aBuf, WAL_HDRSIZE, 0, pWal->hdr.aFrameCksum
);
/* Malloc a buffer to read frames into. */
szFrame = szPage + WAL_FRAME_HDRSIZE;
@@ -809,23 +813,24 @@ static int walIndexRecover(Wal *pWal){
/* If nTruncate is non-zero, this is a commit record. */
if( nTruncate ){
hdr.mxFrame = iFrame;
hdr.nPage = nTruncate;
hdr.szPage = szPage;
pWal->hdr.mxFrame = iFrame;
pWal->hdr.nPage = nTruncate;
pWal->hdr.szPage = szPage;
aFrameCksum[0] = pWal->hdr.aFrameCksum[0];
aFrameCksum[1] = pWal->hdr.aFrameCksum[1];
}
}
sqlite3_free(aFrame);
}else{
memset(&hdr, 0, sizeof(hdr));
}
finished:
if( rc==SQLITE_OK && hdr.mxFrame==0 ){
if( rc==SQLITE_OK && pWal->hdr.mxFrame==0 ){
rc = walIndexRemap(pWal, WALINDEX_MMAP_INCREMENT);
}
if( rc==SQLITE_OK ){
memcpy(&pWal->hdr, &hdr, sizeof(hdr));
pWal->hdr.aFrameCksum[0] = aFrameCksum[0];
pWal->hdr.aFrameCksum[1] = aFrameCksum[1];
walIndexWriteHdr(pWal);
}
return rc;
@@ -1626,25 +1631,35 @@ int sqlite3WalUndo(Wal *pWal, int (*xUndo)(void *, Pgno), void *pUndoCtx){
return rc;
}
/* Return an integer that records the current (uncommitted) write
** position in the WAL
/*
** Argument aWalData must point to an array of WAL_SAVEPOINT_NDATA u32
** values. This function populates the array with values required to
** "rollback" the write position of the WAL handle back to the current
** point in the event of a savepoint rollback (via WalSavepointUndo()).
*/
u32 sqlite3WalSavepoint(Wal *pWal){
void sqlite3WalSavepoint(Wal *pWal, u32 *aWalData){
assert( pWal->lockState==SQLITE_SHM_WRITE );
return pWal->hdr.mxFrame;
aWalData[0] = pWal->hdr.mxFrame;
aWalData[1] = pWal->hdr.aFrameCksum[0];
aWalData[2] = pWal->hdr.aFrameCksum[1];
}
/* Move the write position of the WAL back to iFrame. Called in
** response to a ROLLBACK TO command.
/*
** Move the write position of the WAL back to the point identified by
** the values in the aWalData[] array. aWalData must point to an array
** of WAL_SAVEPOINT_NDATA u32 values that has been previously populated
** by a call to WalSavepoint().
*/
int sqlite3WalSavepointUndo(Wal *pWal, u32 iFrame){
int sqlite3WalSavepointUndo(Wal *pWal, u32 *aWalData){
int rc = SQLITE_OK;
assert( pWal->lockState==SQLITE_SHM_WRITE );
assert( iFrame<=pWal->hdr.mxFrame );
if( iFrame<pWal->hdr.mxFrame ){
assert( aWalData[0]<=pWal->hdr.mxFrame );
if( aWalData[0]<pWal->hdr.mxFrame ){
rc = walIndexMap(pWal, walMappingSize(pWal->hdr.mxFrame));
pWal->hdr.mxFrame = iFrame;
pWal->hdr.mxFrame = aWalData[0];
pWal->hdr.aFrameCksum[0] = aWalData[1];
pWal->hdr.aFrameCksum[1] = aWalData[2];
if( rc==SQLITE_OK ){
walCleanupHash(pWal);
walIndexUnmap(pWal);
@@ -1694,6 +1709,7 @@ int sqlite3WalFrames(
if( rc!=SQLITE_OK ){
return rc;
}
walChecksumBytes(1, aWalHdr, sizeof(aWalHdr), 0, pWal->hdr.aFrameCksum);
}
assert( pWal->szPage==szPage );