1 # 2010 May 25 2 # 3 # The author disclaims copyright to this source code. In place of 4 # a legal notice, here is a blessing: 5 # 6 # May you do good and not evil. 7 # May you find forgiveness for yourself and forgive others. 8 # May you share freely, never taking more than you give. 9 # 10 #*********************************************************************** 11 # 12 13 14 set testdir [file dirname $argv0] 15 source $testdir/tester.tcl 16 source $testdir/lock_common.tcl 17 source $testdir/wal_common.tcl 18 ifcapable !wal {finish_test ; return } 19 20 21 #------------------------------------------------------------------------- 22 # This test case demonstrates a flaw in the wal-index manipulation that 23 # existed at one point: If a process crashes mid-transaction, it may have 24 # already added some entries to one of the hash-tables in the wal-index. 25 # If the transaction were to be explicitly rolled back at this point, the 26 # hash-table entries would be removed as part of the rollback. However, 27 # if the process crashes, the transaction is implicitly rolled back and 28 # the rogue entries remain in the hash table. 29 # 30 # Normally, this causes no problem - readers can tell the difference 31 # between committed and uncommitted entries in the hash table. However, 32 # if it happens often enough that all slots in the hash-table become 33 # non-zero, the next process that attempts to read or write the hash 34 # table falls into an infinite loop. 35 # 36 # Even if run with an SQLite version affected by the bug, this test case 37 # only goes into an infinite loop if SQLite is compiled without SQLITE_DEBUG 38 # defined. If SQLITE_DEBUG is defined, the program is halted by a failing 39 # assert() before entering the infinite loop. 40 # 41 # walcrash2-1.1: Create a database. Commit a transaction that adds 8 frames 42 # to the WAL (and 8 entry to the first hash-table in the 43 # wal-index). 44 # 45 # walcrash2-1.2: Have an external process open a transaction, add 8 entries 46 # to the wal-index hash-table, then crash. Repeat this 1023 47 # times (so that the wal-index contains 8192 entries - all 48 # slots are non-zero). 49 # 50 # walcrash2-1.3: Using a new database connection, attempt to query the 51 # database. This should cause the process to go into the 52 # infinite loop. 53 # 54 do_test walcrash2-1.1 { 55 execsql { 56 PRAGMA page_size = 1024; 57 PRAGMA auto_vacuum = off; 58 PRAGMA journal_mode = WAL; 59 PRAGMA synchronous = NORMAL; 60 BEGIN; 61 CREATE TABLE t1(x); 62 CREATE TABLE t2(x); 63 CREATE TABLE t3(x); 64 CREATE TABLE t4(x); 65 CREATE TABLE t5(x); 66 CREATE TABLE t6(x); 67 CREATE TABLE t7(x); 68 COMMIT; 69 } 70 file size test.db-wal 71 } [wal_file_size 8 1024] 72 for {set nEntry 8} {$nEntry < 8192} {incr nEntry 8} { 73 do_test walcrash2-1.2.[expr $nEntry/8] { 74 set C [launch_testfixture] 75 testfixture $C { 76 sqlite3 db test.db 77 db eval { 78 PRAGMA cache_size = 15; 79 BEGIN; 80 INSERT INTO t1 VALUES(randomblob(900)); -- 1 row, 1 page 81 INSERT INTO t1 SELECT * FROM t1; -- 2 rows, 3 pages 82 INSERT INTO t1 SELECT * FROM t1; -- 4 rows, 5 pages 83 INSERT INTO t1 SELECT * FROM t1; -- 8 rows, 9 pages 84 INSERT INTO t1 SELECT * FROM t1; -- 16 rows, 17 pages 85 INSERT INTO t1 SELECT * FROM t1 LIMIT 3; -- 20 rows, 20 pages 86 } 87 } 88 close $C 89 file size test.db-wal 90 } [wal_file_size 16 1024] 91 } 92 do_test walcrash2-1.3 { 93 sqlite3 db2 test.db 94 execsql { SELECT count(*) FROM t1 } db2 95 } {0} 96 catch { db2 close } 97 98 finish_test 99 100
