Merge with MySQL 5.1.55

- Fixed some issues with partitions and connection_string, which also fixed lp:716890 "Pre- and post-recovery crash in Aria"
- Fixed wrong assert in Aria

Now need to merge with latest xtradb before pushing 

sql/ha_partition.cc:
  Ensure that m_ordered_rec_buffer is not freed before close.
sql/mysqld.cc:
  Changed to use opt_stack_trace instead of opt_pstack.
  Removed references to pstack
sql/partition_element.h:
  Ensure that connect_string is initialized
storage/maria/ma_key_recover.c:
  Fixed wrong assert

1 files changed, 7 insertions, 1 deletions

diff --git a/sql/item_strfunc.cc b/sql/item_strfunc.cc
index 686b5d5fea3..1a83d21d38a 100644
--- a/sql/item_strfunc.cc
+++ b/sql/item_strfunc.cc
@@ -905,9 +905,15 @@ String *Item_func_replace::val_str(String *str)
     search=res2->ptr();
     search_end=search+from_length;
 redo:
+    DBUG_ASSERT(res->ptr() || !offset);
     ptr=res->ptr()+offset;
     strend=res->ptr()+res->length();
-    end=strend-from_length+1;
+    /*
+      In some cases val_str() can return empty string
+      with ptr() == NULL and length() == 0.
+      Let's check strend to avoid overflow.
+    */
+    end= strend ? strend - from_length + 1 : NULL;
     while (ptr < end)
     {
         if (*ptr == *search)