Fix a bug in a test file causing malloc5.test to crash. (CVS 4331)

FossilOrigin-Name: ab09967bd2dd291030850d44c0862fbb7d0d8118

src/test3.c

@@ -13,7 +13,7 @@
 ** is not included in the SQLite library.  It is used for automated
 ** testing of the SQLite library.
 **
-** $Id: test3.c,v 1.84 2007/08/29 17:43:20 drh Exp $
+** $Id: test3.c,v 1.85 2007/08/30 08:27:40 danielk1977 Exp $
 */
 #include "sqliteInt.h"
 #include "btreeInt.h"
@@ -557,6 +557,16 @@ static int btree_pager_stats(
     return TCL_ERROR;
   }
   pBt = sqlite3TextToPtr(argv[1]);
+ 
+  /* Normally in this file, with a b-tree handle opened using the 
+  ** [btree_open] command it is safe to call sqlite3BtreeEnter() directly.
+  ** But this function is sometimes called with a btree handle obtained
+  ** from an open SQLite connection (using [btree_from_db]). In this case
+  ** we need to obtain the mutex for the controlling SQLite handle before
+  ** it is safe to call sqlite3BtreeEnter().
+  */
+  sqlite3_mutex_enter(pBt->pSqlite->mutex);
+
   sqlite3BtreeEnter(pBt);
   a = sqlite3PagerStats(sqlite3BtreePager(pBt));
   for(i=0; i<11; i++){
@@ -570,6 +580,9 @@ static int btree_pager_stats(
     Tcl_AppendElement(interp, zBuf);
   }
   sqlite3BtreeLeave(pBt);
+
+  /* Release the mutex on the SQLite handle that controls this b-tree */
+  sqlite3_mutex_leave(pBt->pSqlite->mutex);
   return TCL_OK;
 }