From 3e8add919a9f5914de0401c53debf5721b71fca7 Mon Sep 17 00:00:00 2001
From: danielk1977 <danielk1977@noemail.net>
Date: Sat, 4 Jul 2009 17:16:00 +0000
Subject: [PATCH] Remove unreachable code from function btreeCursor() in
 btree.c. (CVS 6848)

FossilOrigin-Name: c76a366ed4dc63604ff695b3ee9c183e430a367e
---
 manifest      | 12 ++++++------
 manifest.uuid |  2 +-
 src/btree.c   | 48 ++++++++++++++++++------------------------------
 3 files changed, 25 insertions(+), 37 deletions(-)

diff --git a/manifest b/manifest
index 5b4807c787..983f2c002d 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Remove\sa\sredundant\sbranch\sfrom\sbtree.c.\s(CVS\s6847)
-D 2009-07-04T15:41:03
+C Remove\sunreachable\scode\sfrom\sfunction\sbtreeCursor()\sin\sbtree.c.\s(CVS\s6848)
+D 2009-07-04T17:16:01
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in df9359da7a726ccb67a45db905c5447d5c00c6ef
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -106,7 +106,7 @@ F src/auth.c 802a9439dfa0b8c208b10055cba400e82ef18025
 F src/backup.c 97a3859d8585eb4fcb1e81a795cf4b3fdd82f30f
 F src/bitvec.c 0ef0651714728055d43de7a4cdd95e703fac0119
 F src/btmutex.c 9b899c0d8df3bd68f527b0afe03088321b696d3c
-F src/btree.c 464fbd75cfa198659088e424d5907aa025768628
+F src/btree.c 1c12a097a14ea756696a8a0857e587a1fc5533de
 F src/btree.h 8cae6364735a5cb2d577ddb23fa6d0e655a4b931
 F src/btreeInt.h b31e5ac04181c7e2892c33ab06228c551df6233c
 F src/build.c 867028ee9f63f7bc8eb8d4a720bb98cf9b9a12b4
@@ -740,7 +740,7 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl 672f81d693a03f80f5ae60bfefacd8a349e76746
-P 983cb6924b8a7d3057718b9228c0cb2fbe7f0dc4
-R 40c2a0bb68ce632cd8e5f2261811a36c
+P 133357d2f070ba303deddff59beead1ec8d10521
+R 59d54d3f3ef42572419a3b06be70cd73
 U danielk1977
-Z b09eed1324988822c632e7993ab98935
+Z 270b59a313a8b2cb36f6d34f9f7ea02b
diff --git a/manifest.uuid b/manifest.uuid
index d7d6745645..e4d09636f6 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-133357d2f070ba303deddff59beead1ec8d10521
\ No newline at end of file
+c76a366ed4dc63604ff695b3ee9c183e430a367e
\ No newline at end of file
diff --git a/src/btree.c b/src/btree.c
index a4f8274218..6dfd88d3e2 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -9,7 +9,7 @@
 **    May you share freely, never taking more than you give.
 **
 *************************************************************************
-** $Id: btree.c,v 1.651 2009/07/04 15:41:03 danielk1977 Exp $
+** $Id: btree.c,v 1.652 2009/07/04 17:16:01 danielk1977 Exp $
 **
 ** This file implements a external (disk-based) database using BTrees.
 ** See the header comment on "btreeInt.h" for additional information.
@@ -3166,8 +3166,10 @@ int sqlite3BtreeSavepoint(Btree *p, int op, int iSavepoint){
 
 /*
 ** Create a new cursor for the BTree whose root is on the page
-** iTable.  The act of acquiring a cursor gets a read lock on 
-** the database file.
+** iTable. If a read-only cursor is requested, it is assumed that
+** the caller already has at least a read-only transaction open
+** on the database already. If a write-cursor is requested, then
+** the caller is assumed to have an open write transaction.
 **
 ** If wrFlag==0, then the cursor can only be used for reading.
 ** If wrFlag==1, then the cursor can be used for reading or for
@@ -3201,9 +3203,8 @@ static int btreeCursor(
   struct KeyInfo *pKeyInfo,              /* First arg to comparison function */
   BtCursor *pCur                         /* Space for new cursor */
 ){
-  int rc;
-  Pgno nPage;
-  BtShared *pBt = p->pBt;
+  int rc;                                /* Return code */
+  BtShared *pBt = p->pBt;                /* Shared b-tree handle */
 
   assert( sqlite3BtreeHoldsMutex(p) );
   assert( wrFlag==0 || wrFlag==1 );
@@ -3215,34 +3216,27 @@ static int btreeCursor(
   assert( hasSharedCacheTableLock(p, iTable, pKeyInfo!=0, wrFlag+1) );
   assert( wrFlag==0 || !hasReadConflicts(p, iTable) );
 
+  /* Assert that the caller has opened the required transaction. */
+  assert( p->inTrans>TRANS_NONE );
+  assert( wrFlag==0 || p->inTrans==TRANS_WRITE );
+  assert( pBt->pPage1 && pBt->pPage1->aData );
+
   if( NEVER(wrFlag && pBt->readOnly) ){
     return SQLITE_READONLY;
   }
+  if( iTable==1 && pagerPagecount(pBt)==0 ){
+    return SQLITE_EMPTY;
+  }
 
-  if( pBt->pPage1==0 ){
-    rc = lockBtreeWithRetry(p);
-    if( rc!=SQLITE_OK ){
-      return rc;
-    }
-  }
   pCur->pgnoRoot = (Pgno)iTable;
-  rc = sqlite3PagerPagecount(pBt->pPager, (int *)&nPage); 
-  if( rc!=SQLITE_OK ){
-    return rc;
-  }
-  if( iTable==1 && nPage==0 ){
-    rc = SQLITE_EMPTY;
-    goto create_cursor_exception;
-  }
   rc = getAndInitPage(pBt, pCur->pgnoRoot, &pCur->apPage[0]);
   if( rc!=SQLITE_OK ){
-    goto create_cursor_exception;
+    assert( pCur->apPage[0]==0 );
+    return rc;
   }
 
   /* Now that no other errors can occur, finish filling in the BtCursor
-  ** variables, link the cursor into the BtShared list and set *ppCur (the
-  ** output argument to this function).
-  */
+  ** variables and link the cursor into the BtShared list.  */
   pCur->pKeyInfo = pKeyInfo;
   pCur->pBtree = p;
   pCur->pBt = pBt;
@@ -3254,13 +3248,7 @@ static int btreeCursor(
   pBt->pCursor = pCur;
   pCur->eState = CURSOR_INVALID;
   pCur->cachedRowid = 0;
-
   return SQLITE_OK;
-
-create_cursor_exception:
-  releasePage(pCur->apPage[0]);
-  unlockBtreeIfUnused(pBt);
-  return rc;
 }
 int sqlite3BtreeCursor(
   Btree *p,                                   /* The btree */