From: Date: October 10 2008 10:28pm
Subject: bzr commit into mysql-5.1 branch (davi:2772) Bug#37075
List-Archive: http://lists.mysql.com/commits/56058
X-Bug: 37075
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# At a local mysql-5.1 repository of davi

 2772 Davi Arnaut	2008-10-10
      Bug#37075: offset of limit clause might be truncated to 0 on 32-bits server w/o big tables
      
      The problem is that the offset argument of the limit clause
      might be truncated to 0 on 32-bits server built without big
      tables support. The truncation was happening because the
      original 64-bits long argument was being cast to a 32-bits
      (ha_rows) offset counter.
      
      The solution is to check if the conversing resulted in value
      truncation and if so, the offset is set to the maximum possible
      value that can fit on the type.
modified:
  mysql-test/r/limit.result
  mysql-test/t/limit.test
  sql/sql_lex.cc

per-file messages:
  mysql-test/r/limit.result
    Add test case result for Bug#37075
  mysql-test/t/limit.test
    Add test case for Bug#37075
  sql/sql_lex.cc
    Check for truncation of the offset value. If value was
    truncated, set to the maximum possible value.
=== modified file 'mysql-test/r/limit.result'
--- a/mysql-test/r/limit.result	2008-02-28 14:34:08 +0000
+++ b/mysql-test/r/limit.result	2008-10-10 20:28:40 +0000
@@ -111,3 +111,6 @@ set @a=-14632475938453979136;
 execute s using @a, @a;
 ERROR HY000: Incorrect arguments to EXECUTE
 End of 5.0 tests
+select 1 as a limit 4294967296,10;
+a
+End of 5.1 tests

=== modified file 'mysql-test/t/limit.test'
--- a/mysql-test/t/limit.test	2008-02-28 23:22:50 +0000
+++ b/mysql-test/t/limit.test	2008-10-10 20:28:40 +0000
@@ -95,3 +95,11 @@ set @a=-14632475938453979136;
 execute s using @a, @a;
 
 --echo End of 5.0 tests
+
+#
+# Bug#37075: offset of limit clause might be truncated to 0 on 32-bits server w/o big tables
+#
+
+select 1 as a limit 4294967296,10;
+
+--echo End of 5.1 tests

=== modified file 'sql/sql_lex.cc'
--- a/sql/sql_lex.cc	2008-09-18 08:38:44 +0000
+++ b/sql/sql_lex.cc	2008-10-10 20:28:40 +0000
@@ -2403,8 +2403,13 @@ void st_select_lex_unit::set_limit(st_se
   if (val != (ulonglong)select_limit_val)
     select_limit_val= HA_POS_ERROR;
 #endif
-  offset_limit_cnt= (ha_rows)(sl->offset_limit ? sl->offset_limit->val_uint() :
-                                                 ULL(0));
+  val= sl->offset_limit ? sl->offset_limit->val_uint() : ULL(0);
+  offset_limit_cnt= (ha_rows)val;
+#ifndef BIG_TABLES
+  /* Check for truncation. */
+  if (val != (ulonglong)offset_limit_cnt)
+    offset_limit_cnt= HA_POS_ERROR;
+#endif
   select_limit_cnt= select_limit_val + offset_limit_cnt;
   if (select_limit_cnt < select_limit_val)
     select_limit_cnt= HA_POS_ERROR;		// no limit