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Remove an assert ("assert( subpage>0 )") from btree.c that may not be true for a corrupt database. Also add comments and other assert() statements to btree.c function moveToRoot(). (CVS 6886)

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FossilOrigin-Name: 3151dab9c78106217ec80ebadc666dfd11b42029
This commit is contained in:
danielk1977
2009-07-13 09:41:45 +00:00
parent 3fd7cf5aa1
commit 8f880a8cfb
4 changed files with 59 additions and 13 deletions
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34
src/btree.c
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@@ -9,7 +9,7 @@
** May you share freely, never taking more than you give.
**
*************************************************************************
** $Id: btree.c,v 1.683 2009/07/13 07:30:53 danielk1977 Exp $
** $Id: btree.c,v 1.684 2009/07/13 09:41:45 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** See the header comment on "btreeInt.h" for additional information.
@@ -3974,7 +3974,25 @@ static void moveToParent(BtCursor *pCur){
}
/*
** Move the cursor to the root page
** Move the cursor to point to the root page of its b-tree structure.
**
** If the table has a virtual root page, then the cursor is moved to point
** to the virtual root page instead of the actual root page. A table has a
** virtual root page when the actual root page contains no cells and a
** single child page. This can only happen with the table rooted at page 1.
**
** If the b-tree structure is empty, the cursor state is set to
** CURSOR_INVALID. Otherwise, the cursor is set to point to the first
** cell located on the root (or virtual root) page and the cursor state
** is set to CURSOR_VALID.
**
** If this function returns successfully, it may be assumed that the
** page-header flags indicate that the [virtual] root-page is the expected
** kind of b-tree page (i.e. if when opening the cursor the caller did not
** specify a KeyInfo structure the flags byte is set to 0x05 or 0x0D,
** indicating a table b-tree, or if the caller did specify a KeyInfo
** structure the flags byte is set to 0x02 or 0x0A, indicating an index
** b-tree).
*/
static int moveToRoot(BtCursor *pCur){
MemPage *pRoot;
@@ -3988,6 +4006,7 @@ static int moveToRoot(BtCursor *pCur){
assert( CURSOR_FAULT > CURSOR_REQUIRESEEK );
if( pCur->eState>=CURSOR_REQUIRESEEK ){
if( pCur->eState==CURSOR_FAULT ){
assert( pCur->skip!=SQLITE_OK );
return pCur->skip;
}
sqlite3BtreeClearCursor(pCur);
@@ -4018,8 +4037,16 @@ static int moveToRoot(BtCursor *pCur){
}
}
/* Assert that the root page is of the correct type. This must be the
** case as the call to this function that loaded the root-page (either
** this call or a previous invocation) would have detected corruption
** if the assumption were not true, and it is not possible for the flags
** byte to have been modified while this cursor is holding a reference
** to the page. */
pRoot = pCur->apPage[0];
assert( pRoot->pgno==pCur->pgnoRoot );
assert( pRoot->isInit && (pCur->pKeyInfo==0)==pRoot->intKey );
pCur->aiIdx[0] = 0;
pCur->info.nSize = 0;
pCur->atLast = 0;
@@ -4028,9 +4055,7 @@ static int moveToRoot(BtCursor *pCur){
if( pRoot->nCell==0 && !pRoot->leaf ){
Pgno subpage;
if( pRoot->pgno!=1 ) return SQLITE_CORRUPT_BKPT;
assert( pRoot->pgno==1 );
subpage = get4byte(&pRoot->aData[pRoot->hdrOffset+8]);
assert( subpage>0 );
pCur->eState = CURSOR_VALID;
rc = moveToChild(pCur, subpage);
}else{
@@ -6418,6 +6443,7 @@ int sqlite3BtreeInsert(
pPage = pCur->apPage[pCur->iPage];
assert( pPage->intKey || nKey>=0 );
assert( pPage->leaf || !pPage->intKey );
TRACE(("INSERT: table=%d nkey=%lld ndata=%d page=%d %s\n",
pCur->pgnoRoot, nKey, nData, pPage->pgno,
loc==0 ? "overwrite" : "new entry"));