Avoid leaving a suspect page in the page-cache if an error occurs during sqlite3PagerAcquire(). (CVS 6922)

FossilOrigin-Name: 2594f01c73301f9432be9d007a079a19a3d383f9

manifest

@@ -1,5 +1,5 @@
-C Fix\sa\sdouble-free\sthat\scan\soccur\safter\sdatabase\scorruption\sis\sdetected.\s(CVS\s6921)
-D 2009-07-22T14:08:14
+C Avoid\sleaving\sa\ssuspect\spage\sin\sthe\spage-cache\sif\san\serror\soccurs\sduring\ssqlite3PagerAcquire().\s(CVS\s6922)
+D 2009-07-22T16:41:15
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in df9359da7a726ccb67a45db905c5447d5c00c6ef
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -147,7 +147,7 @@ F src/os_common.h 8c61457df58f1a4bd5f5adc3e90e01b37bf7afbc
 F src/os_os2.c bed77dc26e3a95ce4a204936b9a1ca6fe612fcc5
 F src/os_unix.c cdb2a08b9ce4aa13b3f7b91d4dd60fb48be9f56a
 F src/os_win.c 725c38a524d168ce280446ad8761d731bc516405
-F src/pager.c c1b13280e111d33625b94a8391eb0c3c94a8384d
+F src/pager.c 2149b8271e18aa687456ac4b71ca3b3ad3c26adb
 F src/pager.h 5bd96ed838e4156e0effa5ffe746bce4c0112c24
 F src/parse.y bcd46d43fbd23a22b8c020a3eb1806b794794ed5
 F src/pcache.c 1dae135b70a029f81ed66f6e9b5d0db91480d5d0
@@ -741,7 +741,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl 672f81d693a03f80f5ae60bfefacd8a349e76746
-P 1e510d7fc5cc47fe2714dbb1ed3ea7e90acbff7b
-R 4924080796614e12c97e50a70e0d2fae
+P 5260e8b1048af2e00d49706466d9aded90c24ed2
+R 14853fced115ae521390a355c09db2d4
 U danielk1977
-Z a8cabae79b26acd1023037532366e880
+Z 0b5e9ddfa58a9d8ba46a6641e5839200

manifest.uuid

@@ -1 +1 @@
-5260e8b1048af2e00d49706466d9aded90c24ed2
+2594f01c73301f9432be9d007a079a19a3d383f9

src/pager.c

@@ -18,7 +18,7 @@
 ** file simultaneously, or one process from reading the database while
 ** another is writing.
 **
-** @(#) $Id: pager.c,v 1.612 2009/07/22 13:19:20 drh Exp $
+** @(#) $Id: pager.c,v 1.613 2009/07/22 16:41:15 danielk1977 Exp $
 */
 #ifndef SQLITE_OMIT_DISKIO
 #include "sqliteInt.h"
@@ -3772,18 +3772,6 @@ static void pagerUnlockIfUnused(Pager *pPager){
   }
 }
 
-/*
-** Drop a page from the cache using sqlite3PcacheDrop().
-**
-** If this means there are now no pages with references to them, a rollback
-** occurs and the lock on the database is removed.
-*/
-static void pagerDropPage(DbPage *pPg){
-  Pager *pPager = pPg->pPager;
-  sqlite3PcacheDrop(pPg);
-  pagerUnlockIfUnused(pPager);
-}
-
 /*
 ** Acquire a reference to page number pgno in pager pPager (a page
 ** reference has type DbPage*). If the requested reference is 
@@ -3871,6 +3859,7 @@ int sqlite3PagerAcquire(
   if( (*ppPage)->pPager ){
     /* In this case the pcache already contains an initialized copy of
     ** the page. Return without further ado.  */
+    assert( pgno<=PAGER_MAX_PGNO && pgno!=PAGER_MJ_PGNO(pPager) );
     PAGER_INCR(pPager->nHit);
     return SQLITE_OK;
 
@@ -3923,8 +3912,6 @@ int sqlite3PagerAcquire(
       assert( pPg->pPager==pPager );
       rc = readDbPage(pPg);
       if( rc!=SQLITE_OK ){
-        pagerDropPage(pPg);
-	pPg = 0;
         goto pager_acquire_err;
       }
     }
@@ -3937,8 +3924,11 @@ int sqlite3PagerAcquire(
 
 pager_acquire_err:
   assert( rc!=SQLITE_OK );
-  sqlite3PagerUnref(pPg);
+  if( pPg ){
+    sqlite3PcacheDrop(pPg);
+  }
   pagerUnlockIfUnused(pPager);
+
   *ppPage = 0;
   return rc;
 }