WIP: global readonly variable pcre_frame_size

include/my_sys.h

@@ -227,6 +227,9 @@ extern void (*fatal_error_handler_hook)(uint my_err, const char *str,
 				       myf MyFlags);
 extern uint my_file_limit;
 extern ulonglong my_thread_stack_size;
+#ifndef EMBEDDED_LIBRARY
+extern ulonglong my_pcre_frame_size;
+#endif
 extern int sf_leaking_memory; /* set to 1 to disable memleak detection */
 
 extern void (*proc_info_hook)(void *, const PSI_stage_info *, PSI_stage_info *,

mysys/my_init.c

@@ -45,6 +45,8 @@ my_bool my_init_done= 0;
 uint	mysys_usage_id= 0;              /* Incremented for each my_init() */
 
 ulonglong   my_thread_stack_size= (sizeof(void*) <= 4)? 65536: ((256-16)*1024);
+/* http://pcre.org/original/doc/html/pcrestack.html - replaced by init_pcre value */
+ulonglong   my_pcre_frame_size= 640 + 16;
 
 static ulong atoi_octal(const char *str)
 {

sql/item_cmpfunc.h

@@ -25,6 +25,7 @@
 
 #include "thr_malloc.h"                         /* sql_calloc */
 #include "item_func.h"             /* Item_int_func, Item_bool_func */
+long check_stack_available(long margin, uchar *dummy);
 #define PCRE_STATIC 1             /* Important on Windows */
 #include "pcre.h"                 /* pcre header file */
 
@@ -1576,8 +1577,13 @@ class Regexp_processor_pcre
     m_library_charset(&my_charset_utf8_general_ci),
     m_subpatterns_needed(0)
   {
+#ifndef EMBEDDED_LIBRARY
+   uchar dummy;
    m_pcre_extra.flags= PCRE_EXTRA_MATCH_LIMIT_RECURSION;
-   m_pcre_extra.match_limit_recursion= 100L;
+   m_pcre_extra.match_limit_recursion= check_stack_available(100, &dummy) / my_pcre_frame_size;
+#else
+   m_pcre_extra.flags= 0L;
+#endif
   }
   int default_regex_flags();
   void init(CHARSET_INFO *data_charset, int extra_flags, uint nsubpatterns)

sql/mysqld.cc

@@ -100,6 +100,7 @@
 #include "sp_rcontext.h"
 #include "sp_cache.h"
 #include "sql_reload.h"  // reload_acl_and_cache
+#include "pcre.h"
 
 #ifdef HAVE_POLL_H
 #include <poll.h>
@@ -3503,6 +3504,9 @@ static void init_pcre()
   pcre_free= pcre_stack_free= my_str_free_mysqld;
 #ifndef EMBEDDED_LIBRARY
   pcre_stack_guard= check_enough_stack_size_slow;
+  /* my_pcre_frame_size= -pcre_exec(NULL, NULL, NULL, -999, -999, 0, NULL, 0) + 16;
+  http://pcre.org/original/doc/html/pcrestack.html has reason for + 16 
+  my_pcre_frame_size= -pcre_match(NULL, NULL, NULL, 0, NULL, NULL, 0) + 16; */
 #endif
 }
 

sql/sql_parse.cc

@@ -6208,6 +6208,14 @@ bool check_stack_overrun(THD *thd, long margin,
   return 0;
 }
 
+long check_stack_available(long margin,
+			   uchar *buf __attribute__((unused)))
+{
+  long stack_top;
+  DBUG_ASSERT(current_thd);
+  return my_thread_stack_size - margin \
+         - used_stack(current_thd->thread_stack,(char*) &stack_top);
+}
 
 #define MY_YACC_INIT 1000			// Start with big alloc
 #define MY_YACC_MAX  32000			// Because of 'short'

sql/sql_parse.h

@@ -134,6 +134,7 @@ bool check_simple_select();
 Item *normalize_cond(Item *cond);
 Item *negate_expression(THD *thd, Item *expr);
 bool check_stack_overrun(THD *thd, long margin, uchar *dummy);
+long check_stack_available(long margin, uchar *dummy);
 
 /* Variables */
 

sql/sys_vars.cc

@@ -2493,6 +2493,14 @@ static Sys_var_ulonglong Sys_thread_stack(
        VALID_RANGE(128*1024, ULONGLONG_MAX), DEFAULT(DEFAULT_THREAD_STACK),
        BLOCK_SIZE(1024));
 
+#ifndef EMBEDDED_LIBRARY
+static Sys_var_ulonglong Sys_my_pcre_frame_size(
+       "pcre_frame_size", "Frame size for pcre_recursion",
+       GLOBAL_VAR(my_pcre_frame_size), NO_CMD_LINE,
+       VALID_RANGE(500,1024), DEFAULT(640 + 16), 1, NO_MUTEX_GUARD,
+       NOT_IN_BINLOG, ON_CHECK(0), ON_UPDATE(0));
+#endif
+
 static Sys_var_charptr Sys_tmpdir(
        "tmpdir", "Path for temporary files. Several paths may "
        "be specified, separated by a "