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Overview
Comment:Improved detection and suppression of endless loops in clearDatabasePage().
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SHA1: 30011ad2f55cfcacaf23a58ebcc17b17a7b9355e
User & Date: drh 2015-04-01 13:21:33
References
2015-04-06
22:05
Detect and suppress an endless loops in clearDatabasePage() that might result from a corrupt database file. This is an edited cherry-pick from [30011ad2f55c] and [395bb3e677a]. Leaf check-in: e5f5ef00 user: drh tags: apple-osx-385
Context
2015-04-06
22:05
Detect and suppress an endless loops in clearDatabasePage() that might result from a corrupt database file. This is an edited cherry-pick from [30011ad2f55c] and [395bb3e677a]. Leaf check-in: e5f5ef00 user: drh tags: apple-osx-385
2015-04-02
15:24
Disable e_walauto.test on OpenBSD, as it requires a coherent cache. check-in: 90701227 user: dan tags: trunk
2015-04-01
18:22
Merge latest trunk changes with this branch. check-in: 4621b2ee user: dan tags: sorter-opt
16:39
Merge recent enhancements from trunk. check-in: aea439bd user: drh tags: sessions
16:13
Merge all recent trunk fixes and enhancements into the apple-osx branch. check-in: 71b6f507 user: drh tags: apple-osx
13:21
Improved detection and suppression of endless loops in clearDatabasePage(). check-in: 30011ad2 user: drh tags: trunk
2015-03-31
19:40
On windows, flush the mapping view when syncing content to disk. check-in: a828e73d user: drh tags: trunk
Changes
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Changes to src/btree.c.

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){
  MemPage *pPage;
  int rc;
  unsigned char *pCell;
  int i;
  int hdr;
  u16 szCell;
  u8 hasChildren;

  assert( sqlite3_mutex_held(pBt->mutex) );
  if( pgno>btreePagecount(pBt) ){
    return SQLITE_CORRUPT_BKPT;
  }

  rc = getAndInitPage(pBt, pgno, &pPage, 0);
  if( rc ) return rc;

  hasChildren = !pPage->leaf;
  pPage->leaf = 1;  /* Block looping if the database is corrupt */


  hdr = pPage->hdrOffset;
  for(i=0; i<pPage->nCell; i++){
    pCell = findCell(pPage, i);
    if( hasChildren ){
      rc = clearDatabasePage(pBt, get4byte(pCell), 1, pnChange);
      if( rc ) goto cleardatabasepage_out;
    }
    rc = clearCell(pPage, pCell, &szCell);
    if( rc ) goto cleardatabasepage_out;
  }
  if( hasChildren ){
    rc = clearDatabasePage(pBt, get4byte(&pPage->aData[hdr+8]), 1, pnChange);
    if( rc ) goto cleardatabasepage_out;
  }else if( pnChange ){
    assert( pPage->intKey );
    *pnChange += pPage->nCell;
  }
  if( freePageFlag ){
    freePage(pPage, &rc);
  }else if( (rc = sqlite3PagerWrite(pPage->pDbPage))==0 ){
    zeroPage(pPage, pPage->aData[hdr] | PTF_LEAF);
  }

cleardatabasepage_out:

  releasePage(pPage);
  return rc;
}

/*
** Delete all information from a single table in the database.  iTable is
** the page number of the root of the table.  After this routine returns,







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){
  MemPage *pPage;
  int rc;
  unsigned char *pCell;
  int i;
  int hdr;
  u16 szCell;


  assert( sqlite3_mutex_held(pBt->mutex) );
  if( pgno>btreePagecount(pBt) ){
    return SQLITE_CORRUPT_BKPT;
  }

  rc = getAndInitPage(pBt, pgno, &pPage, 0);
  if( rc ) return rc;
  if( pPage->bBusy ){
    rc = SQLITE_CORRUPT_BKPT;
    goto cleardatabasepage_out;
  }
  pPage->bBusy = 1;
  hdr = pPage->hdrOffset;
  for(i=0; i<pPage->nCell; i++){
    pCell = findCell(pPage, i);
    if( !pPage->leaf ){
      rc = clearDatabasePage(pBt, get4byte(pCell), 1, pnChange);
      if( rc ) goto cleardatabasepage_out;
    }
    rc = clearCell(pPage, pCell, &szCell);
    if( rc ) goto cleardatabasepage_out;
  }
  if( !pPage->leaf ){
    rc = clearDatabasePage(pBt, get4byte(&pPage->aData[hdr+8]), 1, pnChange);
    if( rc ) goto cleardatabasepage_out;
  }else if( pnChange ){
    assert( pPage->intKey );
    *pnChange += pPage->nCell;
  }
  if( freePageFlag ){
    freePage(pPage, &rc);
  }else if( (rc = sqlite3PagerWrite(pPage->pDbPage))==0 ){
    zeroPage(pPage, pPage->aData[hdr] | PTF_LEAF);
  }

cleardatabasepage_out:
  pPage->bBusy = 0;
  releasePage(pPage);
  return rc;
}

/*
** Delete all information from a single table in the database.  iTable is
** the page number of the root of the table.  After this routine returns,

Changes to src/btreeInt.h.

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  u8 intKey;           /* True if table b-trees.  False for index b-trees */
  u8 intKeyLeaf;       /* True if the leaf of an intKey table */
  u8 noPayload;        /* True if internal intKey page (thus w/o data) */
  u8 leaf;             /* True if a leaf page */
  u8 hdrOffset;        /* 100 for page 1.  0 otherwise */
  u8 childPtrSize;     /* 0 if leaf==1.  4 if leaf==0 */
  u8 max1bytePayload;  /* min(maxLocal,127) */

  u16 maxLocal;        /* Copy of BtShared.maxLocal or BtShared.maxLeaf */
  u16 minLocal;        /* Copy of BtShared.minLocal or BtShared.minLeaf */
  u16 cellOffset;      /* Index in aData of first cell pointer */
  u16 nFree;           /* Number of free bytes on the page */
  u16 nCell;           /* Number of cells on this page, local and ovfl */
  u16 maskPage;        /* Mask for page offset */
  u16 aiOvfl[5];       /* Insert the i-th overflow cell before the aiOvfl-th







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  u8 intKey;           /* True if table b-trees.  False for index b-trees */
  u8 intKeyLeaf;       /* True if the leaf of an intKey table */
  u8 noPayload;        /* True if internal intKey page (thus w/o data) */
  u8 leaf;             /* True if a leaf page */
  u8 hdrOffset;        /* 100 for page 1.  0 otherwise */
  u8 childPtrSize;     /* 0 if leaf==1.  4 if leaf==0 */
  u8 max1bytePayload;  /* min(maxLocal,127) */
  u8 bBusy;            /* Prevent endless loops on corrupt database files */
  u16 maxLocal;        /* Copy of BtShared.maxLocal or BtShared.maxLeaf */
  u16 minLocal;        /* Copy of BtShared.minLocal or BtShared.minLeaf */
  u16 cellOffset;      /* Index in aData of first cell pointer */
  u16 nFree;           /* Number of free bytes on the page */
  u16 nCell;           /* Number of cells on this page, local and ovfl */
  u16 maskPage;        /* Mask for page offset */
  u16 aiOvfl[5];       /* Insert the i-th overflow cell before the aiOvfl-th