mysql-5.5.31 merge

1 files changed, 17 insertions, 5 deletions

diff --git a/sql/mysqld.cc b/sql/mysqld.cc
index dfabbcfb82c..d612d920ad4 100644
--- a/sql/mysqld.cc
+++ b/sql/mysqld.cc
@@ -3232,14 +3232,25 @@ sizeof(load_default_groups)/sizeof(load_default_groups[0]);
 
 
 #ifndef EMBEDDED_LIBRARY
-static
-int
-check_enough_stack_size()
+/**
+  This function is used to check for stack overrun for pathological
+  cases of  regular expressions and 'like' expressions.
+  The call to current_thd is  quite expensive, so we try to avoid it
+  for the normal cases.
+  The size of  each stack frame for the wildcmp() routines is ~128 bytes,
+  so checking  *every* recursive call is not necessary.
+ */
+extern "C" int
+check_enough_stack_size(int recurse_level)
 {
   uchar stack_top;
+  if (recurse_level % 16 != 0)
+    return 0;
 
-  return check_stack_overrun(current_thd, STACK_MIN_SIZE,
-                             &stack_top);
+  THD *my_thd= current_thd;
+  if (my_thd != NULL)
+    return check_stack_overrun(my_thd, STACK_MIN_SIZE * 2, &stack_top);
+  return 0;
 }
 #endif
 
@@ -3733,6 +3744,7 @@ static int init_common_variables()
   item_init();
 #ifndef EMBEDDED_LIBRARY
   my_regex_init(&my_charset_latin1, check_enough_stack_size);
+  my_string_stack_guard= check_enough_stack_size;
 #else
   my_regex_init(&my_charset_latin1, NULL);
 #endif