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Overview
Comment:Remove some assert() statements that can fail with corrupt databases.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 7654ae71bd26ae5d713935624d2b6cb8d2e4633f
User & Date: dan 2012-01-12 14:25:55
Context
2012-01-12
15:05
Fix typos in a testcase() macro introduced by the previous commit. check-in: 0467742f user: dan tags: trunk
14:25
Remove some assert() statements that can fail with corrupt databases. check-in: 7654ae71 user: dan tags: trunk
2012-01-11
16:16
Remove code made unreachable by the enhancement of the previous check-in. check-in: 9e31a275 user: drh tags: trunk
Changes
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Changes to src/btree.c.

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  pCur->validNKey = 0;
  if( pNewPage->nCell<1 || pNewPage->intKey!=pCur->apPage[i]->intKey ){
    return SQLITE_CORRUPT_BKPT;
  }
  return SQLITE_OK;
}

#ifndef NDEBUG
/*
** Page pParent is an internal (non-leaf) tree page. This function 
** asserts that page number iChild is the left-child if the iIdx'th
** cell in page pParent. Or, if iIdx is equal to the total number of
** cells in pParent, that page number iChild is the right-child of
** the page.
*/
................................................................................
** the largest cell index.
*/
static void moveToParent(BtCursor *pCur){
  assert( cursorHoldsMutex(pCur) );
  assert( pCur->eState==CURSOR_VALID );
  assert( pCur->iPage>0 );
  assert( pCur->apPage[pCur->iPage] );







  assertParentIndex(
    pCur->apPage[pCur->iPage-1], 
    pCur->aiIdx[pCur->iPage-1], 
    pCur->apPage[pCur->iPage]->pgno
  );



  releasePage(pCur->apPage[pCur->iPage]);
  pCur->iPage--;
  pCur->info.nSize = 0;
  pCur->validNKey = 0;
}

/*
................................................................................
    return SQLITE_OK;
  }
  pCur->skipNext = 0;

  pPage = pCur->apPage[pCur->iPage];
  idx = ++pCur->aiIdx[pCur->iPage];
  assert( pPage->isInit );






  assert( idx<=pPage->nCell );

  pCur->info.nSize = 0;
  pCur->validNKey = 0;
  if( idx>=pPage->nCell ){
    if( !pPage->leaf ){
      rc = moveToChild(pCur, get4byte(&pPage->aData[pPage->hdrOffset+8]));
      if( rc ) return rc;







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  pCur->validNKey = 0;
  if( pNewPage->nCell<1 || pNewPage->intKey!=pCur->apPage[i]->intKey ){
    return SQLITE_CORRUPT_BKPT;
  }
  return SQLITE_OK;
}

#if 0
/*
** Page pParent is an internal (non-leaf) tree page. This function 
** asserts that page number iChild is the left-child if the iIdx'th
** cell in page pParent. Or, if iIdx is equal to the total number of
** cells in pParent, that page number iChild is the right-child of
** the page.
*/
................................................................................
** the largest cell index.
*/
static void moveToParent(BtCursor *pCur){
  assert( cursorHoldsMutex(pCur) );
  assert( pCur->eState==CURSOR_VALID );
  assert( pCur->iPage>0 );
  assert( pCur->apPage[pCur->iPage] );

  /* UPDATE: It is actually possible for the condition tested by the assert
  ** below to be untrue if the database file is corrupt. This can occur if
  ** one cursor has modified page pParent while a reference to it is held 
  ** by a second cursor. Which can only happen if a single page is linked
  ** into more than one b-tree structure in a corrupt database.  */
#if 0
  assertParentIndex(
    pCur->apPage[pCur->iPage-1], 
    pCur->aiIdx[pCur->iPage-1], 
    pCur->apPage[pCur->iPage]->pgno
  );
#endif
  testcase( iIdx>pParent->nCell );

  releasePage(pCur->apPage[pCur->iPage]);
  pCur->iPage--;
  pCur->info.nSize = 0;
  pCur->validNKey = 0;
}

/*
................................................................................
    return SQLITE_OK;
  }
  pCur->skipNext = 0;

  pPage = pCur->apPage[pCur->iPage];
  idx = ++pCur->aiIdx[pCur->iPage];
  assert( pPage->isInit );

  /* If the database file is corrupt, it is possible for the value of idx 
  ** to be invalid here. This can only occur if a second cursor modifies
  ** the page while cursor pCur is holding a reference to it. Which can
  ** only happen if the database is corrupt in such a way as to link the
  ** page into more than one b-tree structure. */
  testcase( idx>pPage->nCell );

  pCur->info.nSize = 0;
  pCur->validNKey = 0;
  if( idx>=pPage->nCell ){
    if( !pPage->leaf ){
      rc = moveToChild(pCur, get4byte(&pPage->aData[pPage->hdrOffset+8]));
      if( rc ) return rc;

Added test/corruptF.test.













































































































































































































































































































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# 2012 January 12
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix corruptF

# Do not use a codec for tests in this file, as the database file is
# manipulated directly using tcl scripts (using the [hexio_write] command).
#
do_not_use_codec

proc str {i} { format %08d $i }

# Create a 6 page database containing a single table - t1. Table t1 
# consists of page 2 (the root page) and pages 5 and 6 (leaf pages). 
# Database pages 3 and 4 are on the free list.
#
proc create_test_db {} {
  catch { db close }
  forcedelete test.db
  sqlite3 db test.db
  db func str str
  execsql {
    PRAGMA auto_vacuum = 0;
    PRAGMA page_size = 1024;
    CREATE TABLE t1(x);         /* root page = 2 */
    CREATE TABLE t2(x);         /* root page = 3 */
    CREATE TABLE t3(x);         /* root page = 4 */

    INSERT INTO t1 VALUES(str(1));
    INSERT INTO t1 SELECT str(rowid+1) FROM t1;
    INSERT INTO t1 SELECT str(rowid+2) FROM t1;
    INSERT INTO t1 SELECT str(rowid+4) FROM t1;
    INSERT INTO t1 SELECT str(rowid+8) FROM t1;
    INSERT INTO t1 SELECT str(rowid+16) FROM t1;
    INSERT INTO t1 SELECT str(rowid+32) FROM t1;
    INSERT INTO t1 SELECT str(rowid+64) FROM t1;
    DROP TABLE t2;
    DROP TABLE t3;
  }
  db close
}

do_test 1.1 { create_test_db } {}

# Check the db is as we expect. 6 pages in total, with 3 and 4 on the free
# list. Page 3 is the free list trunk and page 4 is a leaf.
#
do_test 1.2 { file size test.db } [expr 6*1024]
do_test 1.3 { hexio_read test.db 32 4 } 00000003
do_test 1.4 { hexio_read test.db [expr 2*1024] 12 } 000000000000000100000004

# Change the free-list entry to page 6 and reopen the db file.
do_test 1.5 { 
  hexio_write test.db [expr 2*1024 + 8] 00000006 
  sqlite3 db test.db
} {}

# Now create a new table in the database file. The root of the new table
# is page 6, which is also the right-most leaf page in table t1.
#
do_execsql_test 1.6 { 
  CREATE TABLE t4(x);
  SELECT * FROM sqlite_master;
} {
  table t1 t1 2 {CREATE TABLE t1(x)} 
  table t4 t4 6 {CREATE TABLE t4(x)}
}

# At one point this was causing an assert to fail.
#
# This statement opens a cursor on table t1 and does a full table scan. As
# each row is visited, it is copied into table t4. There is no temporary
# table.
#
# When the t1 cursor reaches page 6 (which is both the right-most leaf of
# t1 and the root of t4), it continues to iterate through the keys within
# it (which at this point are keys that have been inserted into t4). And
# for each row visited, another row is inserted into page 6 - it being the
# root page of t4. Eventually, page 6 becomes full and the height of the
# b-tree for table t4 increased. From the point of view of the t1 cursor,
# this unexpectedly reduces the number of keys on page 6 in the middle of
# its iteration, which causes an assert() to fail.
#
db_save_and_close
if 1 {
for {set i 0} {$i < 128} {incr i} {
  db_restore_and_reopen
  do_test 1.7.$i { 
    set res [
      catchsql { INSERT INTO t4 SELECT x FROM t1 WHERE rowid>$i }
    ]
    if {$res == "0 {}" || $res == "1 {database disk image is malformed}"} {
      set res ""
    }
    set res
  } {}
}
}

do_test 2.1 { create_test_db } {}
do_test 2.2 { file size test.db } [expr 6*1024]
do_test 2.3 { hexio_read test.db 32 4 } 00000003
do_test 2.4 { hexio_read test.db [expr 2*1024] 12 } 000000000000000100000004

# Change the free-list entry to page 5 and reopen the db file.
do_test 2.5 { 
  hexio_write test.db [expr 2*1024 + 8] 00000005 
  sqlite3 db test.db
} {}

# Now create a new table in the database file. The root of the new table
# is page 5, which is also the right-most leaf page in table t1.
#
do_execsql_test 2.6 { 
  CREATE TABLE t4(x);
  SELECT * FROM sqlite_master;
} {
  table t1 t1 2 {CREATE TABLE t1(x)} 
  table t4 t4 5 {CREATE TABLE t4(x)}
}

db_save_and_close
for {set i 127} {$i >= 0} {incr i -1} {
  db_restore_and_reopen
  do_test 2.7.$i { 
    set res [
      catchsql { 
        INSERT INTO t4 SELECT x FROM t1 WHERE rowid<$i ORDER BY rowid DESC 
      }
    ]
    if {$res == "0 {}" || $res == "1 {database disk image is malformed}"} {
      set res ""
    }
    set res
  } {}
}

finish_test