1. fixed bug @2593 "SHOW CREATE TABLE doesn't properly double quotes"

2. added automatic quotation of keywords in SHOW CREATE TABLE

mysql-test/r/show_check.result

@@ -265,3 +265,51 @@ c	decimal(4,3)	YES		NULL
 d	double(4,3)	YES		NULL	
 f	float(4,3)	YES		NULL	
 drop table t1;
+SET sql_mode='';
+SET sql_quote_show_create=OFF;
+CREATE TABLE ```ab``cd``` (i INT);
+SHOW CREATE TABLE ```ab``cd```;
+Table	Create Table
+`ab`cd`	CREATE TABLE ```ab``cd``` (
+  i int(11) default NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE ```ab``cd```;
+CREATE TABLE ```ab````cd``` (i INT);
+SHOW CREATE TABLE ```ab````cd```;
+Table	Create Table
+`ab``cd`	CREATE TABLE ```ab````cd``` (
+  i int(11) default NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE ```ab````cd```;
+CREATE TABLE ```a` (i INT);
+SHOW CREATE TABLE ```a`;
+Table	Create Table
+`a	CREATE TABLE ```a` (
+  i int(11) default NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE ```a`;
+SET sql_mode='ANSI_QUOTES';
+CREATE TABLE """a" (i INT);
+SHOW CREATE TABLE """a";
+Table	Create Table
+"a	CREATE TABLE """a" (
+  i int(11) default NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE """a";
+SET sql_mode='';
+SET sql_quote_show_create=OFF;
+CREATE TABLE t1 (i INT);
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE t1 (
+  i int(11) default NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE t1;
+CREATE TABLE `table` (i INT);
+SHOW CREATE TABLE `table`;
+Table	Create Table
+table	CREATE TABLE `table` (
+  i int(11) default NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+DROP TABLE `table`;
+SET sql_quote_show_create=ON;

mysql-test/t/show_check.test

@@ -142,3 +142,43 @@ drop table t1;
 create table t1 (c decimal(3,3), d double(3,3), f float(3,3));
 show columns from t1;
 drop table t1;
+
+#
+# Test for Bug #2593 "SHOW CREATE TABLE doesn't properly double quotes"
+#
+
+SET sql_mode='';
+SET sql_quote_show_create=OFF;
+
+CREATE TABLE ```ab``cd``` (i INT);
+SHOW CREATE TABLE ```ab``cd```;
+DROP TABLE ```ab``cd```;
+
+CREATE TABLE ```ab````cd``` (i INT);
+SHOW CREATE TABLE ```ab````cd```;
+DROP TABLE ```ab````cd```;
+
+CREATE TABLE ```a` (i INT);
+SHOW CREATE TABLE ```a`;
+DROP TABLE ```a`;
+
+SET sql_mode='ANSI_QUOTES';
+
+CREATE TABLE """a" (i INT);
+SHOW CREATE TABLE """a";
+DROP TABLE """a";
+
+# to test quotes around keywords.. :
+
+SET sql_mode='';
+SET sql_quote_show_create=OFF;
+
+CREATE TABLE t1 (i INT);
+SHOW CREATE TABLE t1;
+DROP TABLE t1;
+
+CREATE TABLE `table` (i INT);
+SHOW CREATE TABLE `table`;
+DROP TABLE `table`;
+
+SET sql_quote_show_create=ON;

sql/mysql_priv.h

@@ -759,6 +759,8 @@ uint find_type(TYPELIB *lib, const char *find, uint length, bool part_match);
 uint check_word(TYPELIB *lib, const char *val, const char *end,
 		const char **end_of_word);
 
+bool is_keyword(const char *name, uint len);
+
 /* sql_parse.cc */
 void free_items(Item *item);
 void cleanup_items(Item *item);

sql/sql_lex.cc

@@ -181,6 +181,23 @@ static int find_keyword(LEX *lex, uint len, bool function)
   return 0;
 }
 
+/*
+  Check if name is a keyword
+
+  SYNOPSIS
+    is_keyword()
+    name      checked name
+    len       length of checked name
+
+  RETURN VALUES
+    0         name is a keyword
+    1         name isn't a keyword
+*/
+
+bool is_keyword(const char *name, uint len)
+{
+  return get_hash_symbol(name,len,0)!=0;
+}
 
 /* make a copy of token before ptr and set yytoklen */
 
@@ -420,7 +437,6 @@ inline static uint int_token(const char *str,uint length)
   return ((uchar) str[-1] <= (uchar) cmp[-1]) ? smaller : bigger;
 }
 
-
 /*
   yylex remember the following states from the following yylex()
 

sql/sql_show.cc

@@ -1086,7 +1086,6 @@ mysqld_dump_create_info(THD *thd, TABLE *table, int fd)
   DBUG_RETURN(0);
 }
 
-/* possible TODO: call find_keyword() from sql_lex.cc here */
 static bool require_quotes(const char *name, uint length)
 {
   uint i, d, c;
@@ -1100,17 +1099,47 @@ static bool require_quotes(const char *name, uint length)
   return 0;
 }
 
+/*
+  Looking for char in multibyte string
+
+  SYNOPSIS
+    look_for_char()
+    name      string for looking at
+    length    length of name
+    q         '\'' or '\"' for looking for
+
+  RETURN VALUES
+    # pointer to found char in string
+    0 string doesn't contain required char
+*/
+
+static const char *look_for_char(const char *name, uint length, char q)
+{
+  const char *cur= name;
+  const char *end= cur+length;
+  uint symbol_length;
+  for (; cur<end; cur+= symbol_length)
+  {
+    char c= *cur;
+    symbol_length= my_mbcharlen(system_charset_info, c);
+    if (symbol_length==1 && c==q)
+      return cur;
+  }
+  return 0;
+}
+
 void
 append_identifier(THD *thd, String *packet, const char *name, uint length)
 {
   char qtype;
+  uint part_len;
+  const char *qplace;
   if (thd->variables.sql_mode & MODE_ANSI_QUOTES)
     qtype= '\"';
   else
     qtype= '`';
 
-  if ((thd->options & OPTION_QUOTE_SHOW_CREATE) ||
-      require_quotes(name, length))
+  if (is_keyword(name,length))
   {
     packet->append(&qtype, 1);
     packet->append(name, length, system_charset_info);
@@ -1118,7 +1147,35 @@ append_identifier(THD *thd, String *packet, const char *name, uint length)
   }
   else
   {
-    packet->append(name, length, system_charset_info);
+    if (!require_quotes(name, length))
+    {
+      if (!(thd->options & OPTION_QUOTE_SHOW_CREATE))
+	packet->append(name, length, system_charset_info);
+      else
+      {
+	packet->append(&qtype, 1);
+	packet->append(name, length, system_charset_info);
+	packet->append(&qtype, 1);
+      }
+    }
+    else
+    {
+      packet->append(&qtype, 1);
+      qplace= look_for_char(name,length,qtype);
+      while (qplace)
+      {
+	if ((part_len= qplace-name))
+	{
+	  packet->append(name, part_len, system_charset_info);
+	  length-= part_len;
+	}
+	packet->append(qplace, 1, system_charset_info);
+	name= qplace;
+	qplace= look_for_char(name+1,length-1,qtype);
+      }
+      packet->append(name, length, system_charset_info);
+      packet->append(&qtype, 1);
+    }
   }
 }