Fix for bug #94: Be sure to journal pages that are added to the freelist then

removed from the freelist and reused during the same transaction. (CVS 660)

FossilOrigin-Name: db178646a01483d59e6f9af302e9bbe394956d93

manifest

@@ -1,5 +1,5 @@
-C All\sthe\scode\sis\snow\sin\splace\sfor\sSQLite\sto\sdistinguish\sbetween\sNUMERIC\sand\nTEXT\sdatatypes.\s\sStill\sneed\sto\sturn\son\sthe\snew\scode\sand\stest\sit.\s(CVS\s659)
-D 2002-07-05T21:42:36
+C Fix\sfor\sbug\s#94:\sBe\ssure\sto\sjournal\spages\sthat\sare\sadded\sto\sthe\sfreelist\sthen\nremoved\sfrom\sthe\sfreelist\sand\sreused\sduring\sthe\ssame\stransaction.\s(CVS\s660)
+D 2002-07-06T16:28:48
 F Makefile.in 6291a33b87d2a395aafd7646ee1ed562c6f2c28c
 F Makefile.template 4e11752e0b5c7a043ca50af4296ec562857ba495
 F README a4c0ba11354ef6ba0776b400d057c59da47a4cc0
@@ -32,7 +32,7 @@ F src/main.c 6ac32ca71ab4728212c5b44aed25e26dc6cfe73c
 F src/md5.c 0ae1f3e2cac92d06fc6246d1b4b8f61a2fe66d3b
 F src/os.c 9cc40c5384baba4a85e160e67807645ca98ba3cc
 F src/os.h 4a361fccfbc4e7609b3e1557f604f94c1e96ad10
-F src/pager.c 58ae9f569b3c664ea9205c6f6da432e3ae180f56
+F src/pager.c 103341600b4044e41b5bd95cd3850f046b976ff2
 F src/pager.h 6fddfddd3b73aa8abc081b973886320e3c614f0e
 F src/parse.y 35437ac29441ce2d34904d8e93f40b7d112147a9
 F src/printf.c 236ed7a79386feed4456fa728fff8be793f1547c
@@ -137,7 +137,7 @@ F www/speed.tcl da8afcc1d3ccc5696cfb388a68982bc3d9f7f00f
 F www/sqlite.tcl ae3dcfb077e53833b59d4fcc94d8a12c50a44098
 F www/tclsqlite.tcl 1db15abeb446aad0caf0b95b8b9579720e4ea331
 F www/vdbe.tcl 2013852c27a02a091d39a766bc87cff329f21218
-P 85793a4f03250166c21007cab3525709592d0866
-R f77acd757b229f1cdb42ab7cac78b933
+P b4737a16c997a6c139d616211fb6bc4b0fae181c
+R 253a44e4b92ce398170a14aa4989c608
 U drh
-Z 6c4c383ead0a1302c4ea68955c9a4a90
+Z 4750e3634de2bc1c9f7bbad93ace444e

manifest.uuid

@@ -1 +1 @@
-b4737a16c997a6c139d616211fb6bc4b0fae181c
+db178646a01483d59e6f9af302e9bbe394956d93

src/pager.c

@@ -18,7 +18,7 @@
 ** file simultaneously, or one process from reading the database while
 ** another is writing.
 **
-** @(#) $Id: pager.c,v 1.47 2002/06/25 14:43:58 drh Exp $
+** @(#) $Id: pager.c,v 1.48 2002/07/06 16:28:48 drh Exp $
 */
 #include "sqliteInt.h"
 #include "pager.h"
@@ -77,6 +77,7 @@ struct PgHdr {
   char inJournal;                /* TRUE if has been written to journal */
   char inCkpt;                   /* TRUE if written to the checkpoint journal */
   char dirty;                    /* TRUE if we need to write back changes */
+  char alwaysRollback;           /* Ignore dont_rollback() calls if true */
   /* SQLITE_PAGE_SIZE bytes of page data follow this header */
   /* Pager.nExtra bytes of local data follow the page data */
 };
@@ -252,14 +253,21 @@ static int pager_unwritelock(Pager *pPager){
   pPager->journalOpen = 0;
   sqliteOsDelete(pPager->zJournal);
   rc = sqliteOsReadLock(&pPager->fd);
-  assert( rc==SQLITE_OK );
   sqliteFree( pPager->aInJournal );
   pPager->aInJournal = 0;
   for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
     pPg->inJournal = 0;
     pPg->dirty = 0;
   }
+  if( rc==SQLITE_OK ){
     pPager->state = SQLITE_READLOCK;
+  }else{
+    /* This can only happen if a process does a BEGIN, then forks and the
+    ** child process does the COMMIT.  Because of the semantics of unix
+    ** file locking, the unlock will fail.
+    */
+    pPager->state = SQLITE_UNLOCK;
+  }
   return rc;
 }
 
@@ -1038,7 +1046,7 @@ int sqlitepager_begin(void *pData){
       sqliteOsReadLock(&pPager->fd);
       return SQLITE_NOMEM;
     }
-    rc = sqliteOsOpenExclusive(pPager->zJournal, &pPager->jfd, 0);
+    rc = sqliteOsOpenExclusive(pPager->zJournal, &pPager->jfd,pPager->tempFile);
     if( rc!=SQLITE_OK ){
       sqliteFree(pPager->aInJournal);
       pPager->aInJournal = 0;
@@ -1190,10 +1198,23 @@ int sqlitepager_iswriteable(void *pData){
 ** Tests show that this optimization, together with the
 ** sqlitepager_dont_rollback() below, more than double the speed
 ** of large INSERT operations and quadruple the speed of large DELETEs.
+**
+** When this routine is called, set the alwaysRollback flag to true.
+** Subsequent calls to sqlitepager_dont_rollback() for the same page
+** will thereafter be ignored.  This is necessary to avoid a problem
+** where a page with data is added to the freelist during one part of
+** a transaction then removed from the freelist during a later part
+** of the same transaction and reused for some other purpose.  When it
+** is first added to the freelist, this routine is called.  When reused,
+** the dont_rollback() routine is called.  But because the page contains
+** critical data, we still need to be sure it gets rolled back in spite
+** of the dont_rollback() call.
 */
 void sqlitepager_dont_write(Pager *pPager, Pgno pgno){
   PgHdr *pPg;
+
   pPg = pager_lookup(pPager, pgno);
+  pPg->alwaysRollback = 1;
   if( pPg && pPg->dirty ){
     if( pPager->dbSize==(int)pPg->pgno && pPager->origDbSize<pPager->dbSize ){
       /* If this pages is the last page in the file and the file has grown
@@ -1221,6 +1242,7 @@ void sqlitepager_dont_rollback(void *pData){
   Pager *pPager = pPg->pPager;
 
   if( pPager->state!=SQLITE_WRITELOCK || pPager->journalOpen==0 ) return;
+  if( pPg->alwaysRollback ) return;
   if( !pPg->inJournal && (int)pPg->pgno <= pPager->origDbSize ){
     assert( pPager->aInJournal!=0 );
     pPager->aInJournal[pPg->pgno/8] |= 1<<(pPg->pgno&7);