In the pager, load the content of pages which were initialized with

noContent==1 if they are subsequently requested with noContent==0. (CVS 3875)

FossilOrigin-Name: d0745a43b6e037d16e1ec38c7c4d961a80d1ef48

manifest

@@ -1,5 +1,5 @@
-C Fix\ssegfaults\sthat\scan\soccur\sif\sa\smalloc\sfailure\shappens\sjust\sbefore\na\sbuilt-in\sfunction\scalls\ssqlite3_value_text().\s(CVS\s3874)
-D 2007-04-25T18:23:53
+C In\sthe\spager,\sload\sthe\scontent\sof\spages\swhich\swere\sinitialized\swith\nnoContent==1\sif\sthey\sare\ssubsequently\srequested\swith\snoContent==0.\s(CVS\s3875)
+D 2007-04-26T12:11:28
 F Makefile.in 8cab54f7c9f5af8f22fd97ddf1ecfd1e1860de62
 F Makefile.linux-gcc 2d8574d1ba75f129aba2019f0b959db380a90935
 F README 9c4e2d6706bdcc3efdd773ce752a8cdab4f90028
@@ -87,7 +87,7 @@ F src/os_unix.c 426b4c03c304ad78746d65d9ba101e0b72e18e23
 F src/os_unix.h 5768d56d28240d3fe4537fac08cc85e4fb52279e
 F src/os_win.c e94903c7dc1c0599c8ddce42efa0b6928068ddc5
 F src/os_win.h 41a946bea10f61c158ce8645e7646b29d44f122b
-F src/pager.c 33c632ce9c228d87f14879a139fa123d43e4bf25
+F src/pager.c cd2770b0f8bd1900b46121009336e7ad03fb274f
 F src/pager.h d652ddf092d2318d00e41f8539760fe8e57c157c
 F src/parse.y b6cfbadb6d5b21b5087d30698ee5af0ebb098767
 F src/pragma.c 3b992b5b2640d6ae25cef05aa6a42cd1d6c43234
@@ -462,7 +462,7 @@ F www/tclsqlite.tcl bb0d1357328a42b1993d78573e587c6dcbc964b9
 F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
 F www/version3.tcl 890248cf7b70e60c383b0e84d77d5132b3ead42b
 F www/whentouse.tcl fc46eae081251c3c181bd79c5faef8195d7991a5
-P 66646d6fda067e19240808aef65fafd8fa177cdd
-R 48b7346bd8cf5e77d4009859f7c6c683
+P 9cb0ed6ee9827bc6884a0195044d5b6ad0de698e
+R 654420a2ec3eb1f548ed11aa685883b0
 U drh
-Z fd08492b87e717e5d32a8be7d387293c
+Z 352203b1a39e1bdcedb9d02c8002561c

manifest.uuid

@@ -1 +1 @@
-9cb0ed6ee9827bc6884a0195044d5b6ad0de698e
+d0745a43b6e037d16e1ec38c7c4d961a80d1ef48

src/pager.c

@@ -18,7 +18,7 @@
 ** file simultaneously, or one process from reading the database while
 ** another is writing.
 **
-** @(#) $Id: pager.c,v 1.329 2007/04/16 15:02:19 drh Exp $
+** @(#) $Id: pager.c,v 1.330 2007/04/26 12:11:28 drh Exp $
 */
 #ifndef SQLITE_OMIT_DISKIO
 #include "sqliteInt.h"
@@ -2922,13 +2922,32 @@ pager_allocate_out:
   return rc;
 }
 
+/*
+** Make sure we have the content for a page.  If the page was
+** previously acquired with noContent==1, then the content was
+** just initialized to zeros instead of being read from disk.
+** But now we need the real data off of disk.  So make sure we
+** have it.  Read it in if we do not have it already.
+*/
+static int pager_get_content(PgHdr *pPg){
+  if( pPg->needRead ){
+    int rc = readDbPage(pPg->pPager, pPg, pPg->pgno);
+    if( rc==SQLITE_OK ){
+      pPg->needRead = 0;
+    }else{
+      return rc;
+    }
+  }
+  return SQLITE_OK;
+}
+
 /*
 ** Acquire a page.
 **
 ** A read lock on the disk file is obtained when the first page is acquired. 
 ** This read lock is dropped when the last page is released.
 **
-** A _get works for any page number greater than 0.  If the database
+** This routine works for any page number greater than 0.  If the database
 ** file is smaller than the requested page, then no actual disk
 ** read occurs and the memory image of the page is initialized to
 ** all zeros.  The extra data appended to a page is always initialized
@@ -2937,12 +2956,12 @@ pager_allocate_out:
 ** The acquisition might fail for several reasons.  In all cases,
 ** an appropriate error code is returned and *ppPage is set to NULL.
 **
-** See also sqlite3PagerLookup().  Both this routine and _lookup() attempt
+** See also sqlite3PagerLookup().  Both this routine and Lookup() attempt
 ** to find a page in the in-memory cache first.  If the page is not already
-** in memory, this routine goes to disk to read it in whereas _lookup()
+** in memory, this routine goes to disk to read it in whereas Lookup()
 ** just returns 0.  This routine acquires a read-lock the first time it
 ** has to go to disk, and could also playback an old journal if necessary.
-** Since _lookup() never goes to disk, it never has to deal with locks
+** Since Lookup() never goes to disk, it never has to deal with locks
 ** or journal files.
 **
 ** If noContent is false, the page contents are actually read from disk.
@@ -2950,8 +2969,9 @@ pager_allocate_out:
 ** of the page at this time, so do not do a disk read.  Just fill in the
 ** page content with zeros.  But mark the fact that we have not read the
 ** content by setting the PgHdr.needRead flag.  Later on, if 
-** sqlite3PagerWrite() is called on this page, that means that the
-** content is needed and the disk read should occur at that point.
+** sqlite3PagerWrite() is called on this page or if this routine is
+** called again with noContent==0, that means that the content is needed
+** and the disk read should occur at that point.
 */
 int sqlite3PagerAcquire(
   Pager *pPager,      /* The pager open on the database file */
@@ -3060,6 +3080,12 @@ int sqlite3PagerAcquire(
     /* The requested page is in the page cache. */
     assert(pPager->nRef>0 || pgno==1);
     PAGER_INCR(pPager->nHit);
+    if( !noContent ){
+      rc = pager_get_content(pPg);
+      if( rc ){
+        return rc;
+      }
+    }
     page_ref(pPg);
   }
   *ppPage = pPg;
@@ -3367,14 +3393,10 @@ static int pager_write(PgHdr *pPg){
   ** can be stored in the rollback journal.  So do the read at this
   ** time.
   */
-  if( pPg->needRead ){
-    rc = readDbPage(pPager, pPg, pPg->pgno);
-    if( rc==SQLITE_OK ){
-      pPg->needRead = 0;
-    }else{
+  rc = pager_get_content(pPg);
+  if( rc ){
     return rc;
   }
-  }
 
   /* Mark the page as dirty.  If the page has already been written
   ** to the journal then we can return right away.