Fix for bug #40552: Race condition around default_directories

                    in load_defaults() 

load_defaults(), my_search_option_files() and 
my_print_default_files()  utilized a global variable 
containing  a pointer to thread local memory. This could lead 
to race conditions when those functions were called with high 
concurrency. 

Fixed by changing the interface of the said functions to avoid 
the necessity for using a global variable.

Since we cannot change load_defaults() prototype for API
compatibility reasons, it was renamed my_load_defaults().
Now load_defaults() is a thread-unsafe wrapper around
a thread-safe version, my_load_defaults().


mysys/default.c:
  1. Added a thread-safe version of load_defaults(), changed
  load_defaults() with the old interface to be a thread-unsafe
  wrapper around the thread-safe version.
  2. Always use a private MEM_ROOT in my_print_default_files, 
  don't use a global variable.
sql-common/client.c:
  Use a thread-safe version of load_defaults().

1 files changed, 5 insertions, 2 deletions

diff --git a/include/my_sys.h b/include/my_sys.h
index 5335b65822f..180bfe0f07d 100644
--- a/include/my_sys.h
+++ b/include/my_sys.h
@@ -842,14 +842,17 @@ extern void *memdup_root(MEM_ROOT *root,const void *str, size_t len);
 extern int get_defaults_options(int argc, char **argv,
                                 char **defaults, char **extra_defaults,
                                 char **group_suffix);
+extern int my_load_defaults(const char *conf_file, const char **groups,
+                            int *argc, char ***argv, const char ***);
 extern int load_defaults(const char *conf_file, const char **groups,
-			 int *argc, char ***argv);
+                         int *argc, char ***argv);
 extern int modify_defaults_file(const char *file_location, const char *option,
                                 const char *option_value,
                                 const char *section_name, int remove_option);
 extern int my_search_option_files(const char *conf_file, int *argc,
                                   char ***argv, uint *args_used,
-                                  Process_option_func func, void *func_ctx);
+                                  Process_option_func func, void *func_ctx,
+                                  const char **default_directories);
 extern void free_defaults(char **argv);
 extern void my_print_default_files(const char *conf_file);
 extern void print_defaults(const char *conf_file, const char **groups);