From 96862072b843e2431f7723b972618982e7d395d5 Mon Sep 17 00:00:00 2001
From: drh <drh@noemail.net>
Date: Wed, 31 Aug 2011 23:57:22 +0000
Subject: [PATCH] Avoid using uninitialized variables after failures in the
 merge sort code.

FossilOrigin-Name: 2869ed28299b1c9f355ecc24635830f7f1249126
---
 manifest       | 12 ++++++------
 manifest.uuid  |  2 +-
 src/vdbesort.c | 43 ++++++++++++++++++++++---------------------
 3 files changed, 29 insertions(+), 28 deletions(-)

diff --git a/manifest b/manifest
index cff029dee2..cf95f75fde 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Formerly,\swe\senabled\sfdatasync()\son\slinux\sonly.\s\sBut\snow\swe\slearn\sthat\nfdatasync()\sis\snot\ssupported\son\sAndroid.\s\sSo\swe\sdisable\sfdatasync()\son\nLinux\stoo.\s\sIt\scan\sbe\sreenabled\sat\scompile-time\sfor\sthose\swho\sreally\sneed\sit.
-D 2011-08-31T21:01:55.686
+C Avoid\susing\suninitialized\svariables\safter\sfailures\sin\sthe\smerge\ssort\scode.
+D 2011-08-31T23:57:22.695
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in d314143fa6be24828021d3f583ad37d9afdce505
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -245,7 +245,7 @@ F src/vdbeapi.c 11dc47987abacb76ad016dcf5abc0dc422482a98
 F src/vdbeaux.c de1e4cab060a45df9ebee68dd63543d14559f0e7
 F src/vdbeblob.c f024f0bf420f36b070143c32b15cc7287341ffd3
 F src/vdbemem.c 5e6effb96dd53d233361cbfaa3f0a43b9af689e9
-F src/vdbesort.c 8a61a6d731cbe612217edf9eece6197f37c9489e
+F src/vdbesort.c f3d043a1bab7409d4a23cd7a35287c3ac440a167
 F src/vdbetrace.c 5d0dc3d5fd54878cc8d6d28eb41deb8d5885b114
 F src/vtab.c 901791a47318c0562cd0c676a2c6ff1bc530e582
 F src/wal.c 3154756177d6219e233d84291d5b05f4e06ff5e9
@@ -961,7 +961,7 @@ F tool/symbols.sh caaf6ccc7300fd43353318b44524853e222557d5
 F tool/tostr.awk e75472c2f98dd76e06b8c9c1367f4ab07e122d06
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
 F tool/warnings.sh b7fdb2cc525f5ef4fa43c80e771636dd3690f9d2
-P 1b124af40a8fa4d3094f24a9213096b66411b8f9
-R e3c435a6ba2306a2d838c8b23577f672
+P 70b5b309568ac55565558d5456aca1e431cfd26b
+R 09e04eb9163c46e529a61f2438cff2a1
 U drh
-Z 9e7ae74ddd5128c7f3fb2205f914d095
+Z bdb2832352809bf647849d42b7aa6060
diff --git a/manifest.uuid b/manifest.uuid
index 5cdc6053a0..67e9d42efe 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-70b5b309568ac55565558d5456aca1e431cfd26b
\ No newline at end of file
+2869ed28299b1c9f355ecc24635830f7f1249126
\ No newline at end of file
diff --git a/src/vdbesort.c b/src/vdbesort.c
index be99d397d3..c3214b3afe 100644
--- a/src/vdbesort.c
+++ b/src/vdbesort.c
@@ -142,8 +142,8 @@ static int vdbeSorterIterNext(
 ){
   int rc;                         /* Return Code */
   int nRead;                      /* Number of bytes read */
-  int nRec;                       /* Size of record in bytes */
-  int iOff;                       /* Size of serialized size varint in bytes */
+  int nRec = 0;                   /* Size of record in bytes */
+  int iOff = 0;                   /* Size of serialized size varint in bytes */
 
   nRead = pIter->iEof - pIter->iReadOff;
   if( nRead>5 ) nRead = 5;
@@ -154,25 +154,26 @@ static int vdbeSorterIterNext(
   }
 
   rc = sqlite3OsRead(pIter->pFile, pIter->aAlloc, nRead, pIter->iReadOff);
-  iOff = getVarint32(pIter->aAlloc, nRec);
-
-  if( rc==SQLITE_OK && (iOff+nRec)>nRead ){
-    int nRead2;                   /* Number of extra bytes to read */
-    if( (iOff+nRec)>pIter->nAlloc ){
-      int nNew = pIter->nAlloc*2;
-      while( (iOff+nRec)>nNew ) nNew = nNew*2;
-      pIter->aAlloc = sqlite3DbReallocOrFree(db, pIter->aAlloc, nNew);
-      if( !pIter->aAlloc ) return SQLITE_NOMEM;
-      pIter->nAlloc = nNew;
+  if( rc==SQLITE_OK ){
+    iOff = getVarint32(pIter->aAlloc, nRec);
+    if( (iOff+nRec)>nRead ){
+      int nRead2;                   /* Number of extra bytes to read */
+      if( (iOff+nRec)>pIter->nAlloc ){
+        int nNew = pIter->nAlloc*2;
+        while( (iOff+nRec)>nNew ) nNew = nNew*2;
+        pIter->aAlloc = sqlite3DbReallocOrFree(db, pIter->aAlloc, nNew);
+        if( !pIter->aAlloc ) return SQLITE_NOMEM;
+        pIter->nAlloc = nNew;
+      }
+  
+      nRead2 = iOff + nRec - nRead;
+      rc = sqlite3OsRead(
+          pIter->pFile, &pIter->aAlloc[nRead], nRead2, pIter->iReadOff+nRead
+      );
     }
-
-    nRead2 = iOff + nRec - nRead;
-    rc = sqlite3OsRead(
-        pIter->pFile, &pIter->aAlloc[nRead], nRead2, pIter->iReadOff+nRead
-    );
   }
 
-  assert( nRec>0 || rc!=SQLITE_OK );
+  assert( rc!=SQLITE_OK || nRec>0 );
   pIter->iReadOff += iOff+nRec;
   pIter->nKey = nRec;
   pIter->aKey = &pIter->aAlloc[iOff];
@@ -543,12 +544,12 @@ static int vdbeSorterInitMerge(
   i64 nByte = 0;                  /* Total bytes in all opened PMAs */
 
   /* Initialize the iterators. */
-  for(i=0; rc==SQLITE_OK && i<SORTER_MAX_MERGE_COUNT; i++){
+  for(i=0; i<SORTER_MAX_MERGE_COUNT; i++){
     VdbeSorterIter *pIter = &pSorter->aIter[i];
     rc = vdbeSorterIterInit(db, pSorter, pSorter->iReadOff, pIter, &nByte);
     pSorter->iReadOff = pIter->iEof;
-    assert( pSorter->iReadOff<=pSorter->iWriteOff || rc!=SQLITE_OK );
-    if( pSorter->iReadOff>=pSorter->iWriteOff ) break;
+    assert( rc!=SQLITE_OK || pSorter->iReadOff<=pSorter->iWriteOff );
+    if( rc!=SQLITE_OK || pSorter->iReadOff>=pSorter->iWriteOff ) break;
   }
 
   /* Initialize the aTree[] array. */
-- 
2.47.2