From 53bb6a47cd67fb988c5cf6f1fff48b5a5023bcd1 Mon Sep 17 00:00:00 2001
From: "cmiller@maint1.mysql.com" <>
Date: Tue, 15 Aug 2006 18:41:21 +0200
Subject: Bug #20908: Crash if select @@""

Zero-length variables caused failures when using the length to look
up the name in a hash.  Instead, signal that no zero-length name can
ever be found and that to encounter one is a syntax error.
---
 sql/gen_lex_hash.cc | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

(limited to 'sql/gen_lex_hash.cc')

diff --git a/sql/gen_lex_hash.cc b/sql/gen_lex_hash.cc
index 7e0b178f7af..e59986092e4 100644
--- a/sql/gen_lex_hash.cc
+++ b/sql/gen_lex_hash.cc
@@ -442,13 +442,16 @@ int main(int argc,char **argv)
   if (get_options(argc,(char **) argv))
     exit(1);
 
+  /* Broken up to indicate that it's not advice to you, gentle reader. */
+  printf("/*\n\n  Do " "not " "edit " "this " "file " "directly!\n\n*/\n");
+
   printf("/* Copyright (C) 2001-2004 MySQL AB\n\
    This software comes with ABSOLUTELY NO WARRANTY. This is free software,\n\
    and you are welcome to modify and redistribute it under the GPL license\n\
    \n*/\n\n");
 
-  printf("/* This code is generated by gen_lex_hash.cc that seeks for\
- a perfect\nhash function */\n\n");
+  printf("/* Do " "not " "edit " "this " "file!  This is generated by "
+         "gen_lex_hash.cc\nthat seeks for a perfect hash function */\n\n");
   printf("#include \"lex.h\"\n\n");
 
   calc_length();
@@ -468,6 +471,12 @@ static inline SYMBOL *get_hash_symbol(const char *s,\n\
 {\n\
   register uchar *hash_map;\n\
   register const char *cur_str= s;\n\
+\n\
+  if (len == 0) {\n\
+    DBUG_PRINT(\"warning\", (\"get_hash_symbol() received a request for a zero-length symbol, which is probably a mistake.\"));\
+    return(NULL);\n\
+  }\
+\n\
   if (function){\n\
     if (len>sql_functions_max_len) return 0;\n\
     hash_map= sql_functions_map;\n\
-- 
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