Fix a bug in DROP TABLE that could cause SQLITE_MASTER table corruption.

The root problem was that the sequence of BTree operations (Delete, Next)
would not always leave the cursor pointing at the first entry after the
entry that was deleted.  A consequence of this error was that a DROP TABLE
on a table with indices would not always remove every index associated
with that table from the SQLITE_MASTER table.  Subsequent attempts to
open the database will fail when the index for the missing table was
parsed.  Changes have also been made to ignore extra indices in the
SQLITE_MASTER table so that a database previously corrupted by this bug
is once again readable. (CVS 316)

FossilOrigin-Name: 8a984667113564f2bac7412165b6ff8b7e3e8f70

VERSION

@@ -1 +1 @@
-2.1.1
+2.1.2

manifest

@@ -1,9 +1,9 @@
-C Fix\sa\sbug\sin\sthe\slocking\sprotocol.\s(CVS\s315)
+C Fix\sa\sbug\sin\sDROP\sTABLE\sthat\scould\scause\sSQLITE_MASTER\stable\scorruption.\nThe\sroot\sproblem\swas\sthat\sthe\ssequence\sof\sBTree\soperations\s(Delete,\sNext)\nwould\snot\salways\sleave\sthe\scursor\spointing\sat\sthe\sfirst\sentry\safter\sthe\nentry\sthat\swas\sdeleted.\s\sA\sconsequence\sof\sthis\serror\swas\sthat\sa\sDROP\sTABLE\non\sa\stable\swith\sindices\swould\snot\salways\sremove\severy\sindex\sassociated\nwith\sthat\stable\sfrom\sthe\sSQLITE_MASTER\stable.\s\sSubsequent\sattempts\sto\nopen\sthe\sdatabase\swill\sfail\swhen\sthe\sindex\sfor\sthe\smissing\stable\swas\nparsed.\s\sChanges\shave\salso\sbeen\smade\sto\signore\sextra\sindices\sin\sthe\nSQLITE_MASTER\stable\sso\sthat\sa\sdatabase\spreviously\scorrupted\sby\sthis\sbug\nis\sonce\sagain\sreadable.\s(CVS\s316)
-D 2001-11-22T00:01:27
+D 2001-11-23T00:24:12
 F Makefile.in 6801df952cb1df64aa32e4de85fed24511d28efd
 F Makefile.template 1fdb891f14083ee0b63cf7282f91529634438e7a
 F README a4c0ba11354ef6ba0776b400d057c59da47a4cc0
-F VERSION d9c9ad4098db7cbc9f2ecb3ad59fdfb337996198
+F VERSION c5cc20339d1ecb09a252aeef3d5417cd4d802473
 F aclocal.m4 11faa843caa38fd451bc6aeb43e248d1723a269d
 F config.guess f38b1e93d1e0fa6f5a6913e9e7b12774b9232588
 F config.log 6a73d03433669b10a3f0c221198c3f26b9413914
@@ -19,7 +19,7 @@ F libtool c56e618713c9510a103bda6b95f3ea3900dcacd6
 F ltmain.sh e9ed72eb1d690f447c13945eaf69e28af531eda1
 F publish.sh 33cbe6798969f637698044023c139080e5d772a6
 F src/TODO af7f3cab0228e34149cf98e073aa83d45878e7e6
-F src/btree.c ef8934adc4ee61b4028ade1d6ed7ae1f74090e31
+F src/btree.c d40fa46c8c578f1d166f4ea70d7a9d365399e0f3
 F src/btree.h 0250a0a577a98cc64ddf1582d50c08b8d2451650
 F src/build.c 2e21d425328e7c8bd6ade235e9eef51bf6fa870f
 F src/delete.c 5d93a21c1388cfb1359bda01c072f25583a2f4f2
@@ -27,7 +27,7 @@ F src/expr.c 53515a7ba787bf4f0b3f73be30eb86aadb6f1b90
 F src/hash.c 6f1a7712ae3aac8351662969aec5693740a2fbf7
 F src/hash.h a5f5b3ce2d086a172c5879b0b06a27a82eac9fac
 F src/insert.c 3526be771a01035198bef28d8f370cbcab94f46d
-F src/main.c 0b0e7244c7af91613111d5b72387e33f8789ed72
+F src/main.c 799bdaf30cb33409b04a282aac53a9616d707c0d
 F src/md5.c 52f677bfc590e09f71d07d7e327bd59da738d07c
 F src/os.c d7dc681438f311cf8211a78d8d87a7cbdccc2f14
 F src/os.h bed702c9e3b768bc3cb1b12c90b83d099c1546be
@@ -54,14 +54,15 @@ F src/vdbe.h cd4c8647051a0c22c0e133c375f1cd17bb8b1e06
 F src/where.c 05d27a01e53c20b8cd10589b7e789b2a64367988
 F test/all.test 2a51e5395ac7c2c539689b123b9782a05e3837fe
 F test/bigrow.test 1f098f85586d2117bdb3412d27eba45252bc8a6e
-F test/btree.test 47952c7a0c22660566264c68c0664592b7da85ce
+F test/btree.test 6ab4dc5f595905a276ef588fad3c9236dc07a47b
 F test/btree2.test 08e9485619265cbaf5d11bd71f357cdc26bb87e0
+F test/btree3.test 9caa9e22491dd8cd8aa36d7ac3b48b089817c895
 F test/copy.test 768e6f1701a07d08090e1ca7f7dcce0a7a72b43e
 F test/delete.test c904a62129fe102b314a96111a8417f10249e4d8
 F test/expr.test b4171c84b767f7b7e94dbce4824ba8e981a1c72f
 F test/func.test 9012f7fc5369422c890e93549aa61d762e0c8bb3
 F test/in.test 9323681388be301dc73f370b4cd62c5a33f79d1e
-F test/index.test c58829080a24aed3f897d7a77d9592aea30164fa
+F test/index.test c2c3088648d106a5a612a14cb346998a4ff77bfa
 F test/insert.test a5c122aa726f1cef6f07d6767e8fd6f220994c11
 F test/insert2.test d6901ca931e308fea7fca8c95ebe7dc957cc9fc2
 F test/ioerr.test 57d9bffaca18b34f9e976f786eadc2591d6efc6a
@@ -76,7 +77,7 @@ F test/quick.test 6f023c7a73fc413e6d65b7a1879c79764038dc05
 F test/quote.test 286db944717afa9a9bf829dd85e59185c65d5435
 F test/rowid.test ba56df896cb913b70d06661d960869e310fe426e
 F test/select1.test 13aa0a5545209a73d1073cb9062a1b9075b734ae
-F test/select2.test 070c7ac1a66e294004a2a1bfdc9cd2f4d29c1e6e
+F test/select2.test ed2c1882857106b85478f54f67000e14966be4c4
 F test/select3.test 5e1fe8e5a4e63fb2827ab3b89527e0fd4ae35259
 F test/select4.test 29a2ffb187f3d8b6ca42a0a6b619e9cabe12e228
 F test/select5.test c2a6c4a003316ee42cbbd689eebef8fdce0db2ac
@@ -103,7 +104,7 @@ F www/arch.fig d5f9752a4dbf242e9cfffffd3f5762b6c63b3bcf
 F www/arch.png 82ef36db1143828a7abc88b1e308a5f55d4336f4
 F www/arch.tcl 03b521d252575f93b9c52f7c8b0007011512fcfb
 F www/c_interface.tcl d446234c1d3ed747fcefd30e972a19f2b2fc0e05
-F www/changes.tcl c3b863396d8d3966439e631b39b0a845062505db
+F www/changes.tcl f1a09dfa633183121d7d4255f4cadadc84dc034d
 F www/crosscompile.tcl c99efacb3aefaa550c6e80d91b240f55eb9fd33e
 F www/download.tcl 3e51c9ff1326b0a182846134987301310dff7d60
 F www/dynload.tcl 02eb8273aa78cfa9070dd4501dca937fb22b466c
@@ -115,7 +116,7 @@ F www/speed.tcl 212a91d555384e01873160d6a189f1490c791bc2
 F www/sqlite.tcl 6a21242a272e9c0939a04419a51c3d50cae33e3e
 F www/tclsqlite.tcl 13d50723f583888fc80ae1a38247c0ab415066fa
 F www/vdbe.tcl eb4e1768cffa266cbbb7133488022a7a6cb278d9
-P 03673adbfe0c8a92d79f86ddf1136736594208ad
+P a9db1c12c5a4d5741de0e5eb5aa87c647a5646b8
-R 6db2507abc73fcd18a105f2aaf8fbb99
+R c4b924c66bb520eb6ed8e5503bdf1605
 U drh
-Z 5464cc9093ffef5c17cabdd72823cca6
+Z ef51c9b0a8111962938d6717ff48b7e2

manifest.uuid

@@ -1 +1 @@
-a9db1c12c5a4d5741de0e5eb5aa87c647a5646b8
+8a984667113564f2bac7412165b6ff8b7e3e8f70

src/btree.c

@@ -9,7 +9,7 @@
 **    May you share freely, never taking more than you give.
 **
 *************************************************************************
-** $Id: btree.c,v 1.40 2001/11/21 02:21:12 drh Exp $
+** $Id: btree.c,v 1.41 2001/11/23 00:24:12 drh Exp $
 **
 ** This file implements a external (disk-based) database using BTrees.
 ** For a detailed discussion of BTrees, refer to
@@ -1327,7 +1327,7 @@ int sqliteBtreeNext(BtCursor *pCur, int *pRes){
     if( pRes ) *pRes = 1;
     return SQLITE_ABORT;
   }
-  if( pCur->bSkipNext ){
+  if( pCur->bSkipNext && pCur->idx<pCur->pPage->nCell ){
     pCur->bSkipNext = 0;
     if( pRes ) *pRes = 0;
     return SQLITE_OK;
@@ -2194,14 +2194,18 @@ int sqliteBtreeDelete(BtCursor *pCur){
     if( rc ) return rc;
     pCur->bSkipNext = 1;
     dropCell(leafCur.pPage, leafCur.idx, szNext);
-    rc = balance(pCur->pBt, leafCur.pPage, 0);
+    rc = balance(pCur->pBt, leafCur.pPage, pCur);
     releaseTempCursor(&leafCur);
   }else{
     dropCell(pPage, pCur->idx, cellSize(pCell));
     if( pCur->idx>=pPage->nCell ){
       pCur->idx = pPage->nCell-1;
-      if( pCur->idx<0 ){ pCur->idx = 0; }
+      if( pCur->idx<0 ){ 
-      pCur->bSkipNext = 0;
+        pCur->idx = 0;
+        pCur->bSkipNext = 1;
+      }else{
+        pCur->bSkipNext = 0;
+      }
     }else{
       pCur->bSkipNext = 1;
     }

src/main.c

@@ -14,7 +14,7 @@
 ** other files are for internal use by SQLite and should not be
 ** accessed by users of the library.
 **
-** $Id: main.c,v 1.49 2001/11/07 16:48:27 drh Exp $
+** $Id: main.c,v 1.50 2001/11/23 00:24:12 drh Exp $
 */
 #include "sqliteInt.h"
 #include "os.h"
@@ -63,7 +63,7 @@ static int sqliteOpenCb(void *pDb, int argc, char **argv, char **azColName){
         sParse.db = db;
         sParse.initFlag = 1;
         sParse.newTnum = atoi(argv[2]);
-        nErr = sqliteRunParser(&sParse, argv[3], 0);
+        sqliteRunParser(&sParse, argv[3], 0);
       }else{
         /* If the SQL column is blank it means this is an index that
         ** was created to be the PRIMARY KEY or to fulfill a UNIQUE

test/btree.test

@@ -11,7 +11,7 @@
 # This file implements regression tests for SQLite library.  The
 # focus of this script is btree database backend
 #
-# $Id: btree.test,v 1.10 2001/09/23 02:35:53 drh Exp $
+# $Id: btree.test,v 1.11 2001/11/23 00:24:12 drh Exp $
 
 
 set testdir [file dirname $argv0]
@@ -997,11 +997,11 @@ do_test btree-13.1 {
 #   4.  Implement btree_sanity and put it throughout this script
 #
 
-do_test btree-10.98 {
+do_test btree-15.98 {
   btree_close_cursor $::c1
   lindex [btree_pager_stats $::b1] 1
 } {1}
-do_test btree-10.99 {
+do_test btree-15.99 {
   btree_rollback $::b1
   lindex [btree_pager_stats $::b1] 1
 } {0}

test/btree3.test

@@ -0,0 +1,78 @@
+# 2001 November 22
+#
+# 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.
+#
+#***********************************************************************
+# This file implements regression tests for SQLite library.  The
+# focus of this script is btree database backend
+#
+# In particular, this file tests a small part of the Delete logic
+# for the BTree backend.  When a row is deleted from a table, the
+# cursor is suppose to be left pointing at either the previous or
+# next entry in that table.  If the cursor is left pointing at the
+# next entry, then the next Next operation is ignored.  So the 
+# sequence of operations (Delete, Next) should always leave the
+# cursor pointing at the first entry past the one that was deleted.
+# This test is designed to verify that behavior.
+#
+# $Id: btree3.test,v 1.1 2001/11/23 00:24:12 drh Exp $
+
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+if {[info commands btree_open]!=""} {
+
+# Open a test database.
+#
+file delete -force test1.bt
+file delete -force test1.bt-journal
+set b1 [btree_open test1.bt]
+btree_begin_transaction $::b1
+
+# Insert a few one records
+#
+set data {abcdefghijklmnopqrstuvwxyz0123456789}
+append data $data
+append data $data
+append data $data
+append data $data
+for {set k 2} {$k<=10} {incr k} {
+  for {set j 1} {$j<=$k} {incr j} {
+    set jkey [format %02d $j]
+    btree_clear_table $::b1 2
+    set ::c1 [btree_cursor $::b1 2 1]
+    for {set i 1} {$i<=$k+1} {incr i} {
+      set key [format %02d $i]
+      do_test btree3-$k.$j.1.$i {
+        btree_insert $::c1 $::key $::data
+      } {}
+      # btree_tree_dump $::b1 2
+    }
+    do_test btree3-$k.$j.2 {
+      btree_move_to $::c1 $::jkey
+      btree_key $::c1
+    } $::jkey
+    do_test btree3-$k.$j.3 {
+      btree_delete $::c1
+    } {}
+    do_test btree3-$k.$j.4 {
+      btree_next $::c1
+      btree_key $::c1
+    } [format %02d [expr $j+1]]
+    btree_close_cursor $::c1
+  }
+}
+
+btree_rollback $::b1    
+btree_pager_ref_dump $::b1
+btree_close $::b1
+
+} ;# end if( not mem: and has pager_open command );
+
+finish_test

test/index.test

@@ -11,7 +11,7 @@
 # This file implements regression tests for SQLite library.  The
 # focus of this file is testing the CREATE INDEX statement.
 #
-# $Id: index.test,v 1.15 2001/11/08 00:45:22 drh Exp $
+# $Id: index.test,v 1.16 2001/11/23 00:24:12 drh Exp $
 
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
@@ -189,6 +189,16 @@ do_test index-6.3 {
   execsql {DROP TABLE test2}
   execsql {SELECT name FROM sqlite_master WHERE type!='meta' ORDER BY name}
 } {}
+do_test index-6.4 {
+  execsql {
+    CREATE TABLE test1(a,b);
+    CREATE INDEX index1 ON test1(a);
+    CREATE INDEX index2 ON test1(b);
+    CREATE INDEX index3 ON test1(a,b);
+    DROP TABLE test1;
+    SELECT name FROM sqlite_master WHERE type!='meta' ORDER BY name;
+  }
+} {}
 
 # Create a primary key
 #

test/select2.test

@@ -11,7 +11,7 @@
 # This file implements regression tests for SQLite library.  The
 # focus of this file is testing the SELECT statement.
 #
-# $Id: select2.test,v 1.15 2001/11/08 00:45:22 drh Exp $
+# $Id: select2.test,v 1.16 2001/11/23 00:24:13 drh Exp $
 
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
@@ -26,6 +26,7 @@ for {set i 0} {$i<=30} {incr i} {
 close $f
 execsql {COPY tbl1 FROM './testdata1.txt'}
 file delete -force ./testdata1.txt
+catch {unset data}
 
 # Do a second query inside a first.
 #

www/changes.tcl

@@ -17,9 +17,16 @@ proc chng {date desc} {
   puts "<DD><P><UL>$desc</UL></P></DD>"
 }
 
-chng {2001 Nov ?? (2.1.2)} {
+chng {2001 Nov 22 (2.1.2)} {
 <li>Changes to support 64-bit architectures.</li>
 <li>Fix a bug in the locking protocol.</li>
+<li>Fix a bug that could (rarely) cause the database to become 
+    unreadable after a DROP TABLE due to corruption to the SQLITE_MASTER
+    table.</li>
+<li>Change the code so that version 2.1.1 databases that were rendered 
+    unreadable by the above bug can be read by this version of
+    the library even though the SQLITE_MASTER table is (slightly)
+    corrupted.</li>
 }
 
 chng {2001 Nov 13 (2.1.1)} {
@@ -40,7 +47,7 @@ chng {2001 Nov 3 (2.0.8)} {
 <li>Documentation updates</li>
 <li>Simplify the design of the VDBE by restricting the number of sorters
     and lists to 1.
-    In practice, no more than one sorter and one list was every used anyhow.
+    In practice, no more than one sorter and one list was ever used anyhow.
     </li>
 }