Bug#46586: When using the plugin interface the type "set" for options caused a crash.

"What do you mean, there's a bug? There isn't even code!"

There was some token code for plug-in variables of the SET type,
but clearly this never worked, or was subject to massive bit rot
since. Bug-fixes ... fail-safes ... tests -- fais au mieux, mon chou!

mysys/my_getopt.c:
  SETs set-up should set up a default value, but no min/max bounding.
mysys/typelib.c:
  fail-safe requested by serg: don't try to skip separator when we're
  already at end of string.
sql/sql_plugin.cc:
  check_func_set:
  Initialize error_len as find_set() will only update it on error,
  and we're using the value to see whether an error has occurred (!= 0),
  so we'd better not have a random val in there.
  
  value_ptr:
  There's no guarantee we're handed string lengths, so play it safe!
  Use prepared string lengths where possible for minimum speed gain,
  otherwise determine on the fly!

1 files changed, 4 insertions, 2 deletions

diff --git a/sql/sql_plugin.cc b/sql/sql_plugin.cc
index b411d5e3095..bafc601d142 100644
--- a/sql/sql_plugin.cc
+++ b/sql/sql_plugin.cc
@@ -2066,7 +2066,7 @@ static int check_func_set(THD *thd, struct st_mysql_sys_var *var,
   const char *strvalue= "NULL", *str;
   TYPELIB *typelib;
   ulonglong result;
-  uint error_len;
+  uint error_len= 0;                            // init as only set on error
   bool not_used;
   int length;
 
@@ -2665,7 +2665,9 @@ uchar* sys_var_pluginvar::value_ptr(THD *thd, enum_var_type type,
     {
       if (!(value & mask))
         continue;
-      str.append(typelib->type_names[i], typelib->type_lengths[i]);
+      str.append(typelib->type_names[i], typelib->type_lengths
+                                       ? typelib->type_lengths[i]
+                                       : strlen(typelib->type_names[i]));
       str.append(',');
     }