fix for bug #12595 (ESCAPE must be exactly 1 character long)

ESCAPE has length of 1 if specified and sql_mode is NO_BACKSLASH_ESCAPES
or has length of 0 or 1 in every other situation.
(approved patch applied on a up-to-date tree re-commit) 

mysql-test/r/select.result

@@ -2965,6 +2965,63 @@ NULL
 SELECT IFNULL(NULL, NULL);
 IFNULL(NULL, NULL)
 NULL
+SET @OLD_SQL_MODE12595=@@SQL_MODE, @@SQL_MODE='';
+SHOW LOCAL VARIABLES LIKE 'SQL_MODE';
+Variable_name	Value
+sql_mode	
+CREATE TABLE BUG_12595(a varchar(100));
+INSERT INTO BUG_12595 VALUES ('hakan%'), ('hakank'), ("ha%an");
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan\%';
+a
+hakan%
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan*%' ESCAPE '*';
+a
+hakan%
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan**%' ESCAPE '**';
+ERROR HY000: Incorrect arguments to ESCAPE
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan%' ESCAPE '';
+a
+hakan%
+hakank
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan\%' ESCAPE '';
+a
+SELECT * FROM BUG_12595 WHERE a LIKE 'ha\%an' ESCAPE 0x5c;
+a
+ha%an
+SELECT * FROM BUG_12595 WHERE a LIKE 'ha%%an' ESCAPE '%';
+a
+ha%an
+SELECT * FROM BUG_12595 WHERE a LIKE 'ha\%an' ESCAPE '\\';
+a
+ha%an
+SELECT * FROM BUG_12595 WHERE a LIKE 'ha|%an' ESCAPE '|';
+a
+ha%an
+SET @@SQL_MODE='NO_BACKSLASH_ESCAPES';
+SHOW LOCAL VARIABLES LIKE 'SQL_MODE';
+Variable_name	Value
+sql_mode	NO_BACKSLASH_ESCAPES
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan\%';
+a
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan*%' ESCAPE '*';
+a
+hakan%
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan**%' ESCAPE '**';
+ERROR HY000: Incorrect arguments to ESCAPE
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan\%' ESCAPE '\\';
+ERROR HY000: Incorrect arguments to ESCAPE
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan%' ESCAPE '';
+ERROR HY000: Incorrect arguments to ESCAPE
+SELECT * FROM BUG_12595 WHERE a LIKE 'ha\%an' ESCAPE 0x5c;
+a
+ha%an
+SELECT * FROM BUG_12595 WHERE a LIKE 'ha|%an' ESCAPE '|';
+a
+ha%an
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan\n%' ESCAPE '\n';
+ERROR HY000: Incorrect arguments to ESCAPE
+SET @@SQL_MODE=@OLD_SQL_MODE12595;
+DROP TABLE BUG_12595;
 create table t1 (a char(1));
 create table t2 (a char(1));
 insert into t1 values ('a'),('b'),('c');

mysql-test/t/select.test

@@ -2517,6 +2517,45 @@ SELECT CAST(IFNULL(NULL, NULL) AS DECIMAL);
 SELECT ABS(IFNULL(NULL, NULL));
 SELECT IFNULL(NULL, NULL);
 
+#
+# BUG #12595 (ESCAPE must be exactly one)
+#
+SET @OLD_SQL_MODE12595=@@SQL_MODE, @@SQL_MODE='';
+SHOW LOCAL VARIABLES LIKE 'SQL_MODE';
+
+CREATE TABLE BUG_12595(a varchar(100));
+INSERT INTO BUG_12595 VALUES ('hakan%'), ('hakank'), ("ha%an");
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan\%';
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan*%' ESCAPE '*';
+-- error 1210
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan**%' ESCAPE '**';
+# this should work when sql_mode is not NO_BACKSLASH_ESCAPES
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan%' ESCAPE '';
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan\%' ESCAPE '';
+SELECT * FROM BUG_12595 WHERE a LIKE 'ha\%an' ESCAPE 0x5c;
+SELECT * FROM BUG_12595 WHERE a LIKE 'ha%%an' ESCAPE '%';
+SELECT * FROM BUG_12595 WHERE a LIKE 'ha\%an' ESCAPE '\\';
+SELECT * FROM BUG_12595 WHERE a LIKE 'ha|%an' ESCAPE '|';
+
+SET @@SQL_MODE='NO_BACKSLASH_ESCAPES';
+SHOW LOCAL VARIABLES LIKE 'SQL_MODE';
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan\%';
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan*%' ESCAPE '*';
+-- error 1210
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan**%' ESCAPE '**';
+-- error 1210
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan\%' ESCAPE '\\';
+#this gives an error when NO_BACKSLASH_ESCAPES is set
+-- error 1210
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan%' ESCAPE '';
+SELECT * FROM BUG_12595 WHERE a LIKE 'ha\%an' ESCAPE 0x5c;
+SELECT * FROM BUG_12595 WHERE a LIKE 'ha|%an' ESCAPE '|';
+-- error 1210
+SELECT * FROM BUG_12595 WHERE a LIKE 'hakan\n%' ESCAPE '\n';
+
+SET @@SQL_MODE=@OLD_SQL_MODE12595;
+DROP TABLE BUG_12595;
+
 #
 # Bug #6495 Illogical requirement for column qualification in NATURAL join
 #

sql/item_cmpfunc.cc

@@ -2958,6 +2958,15 @@ bool Item_func_like::fix_fields(THD *thd, Item **ref)
     String *escape_str= escape_item->val_str(&tmp_value1);
     if (escape_str)
     {
+      if (escape_used_in_parsing && (
+             (((thd->variables.sql_mode & MODE_NO_BACKSLASH_ESCAPES) &&
+                escape_str->numchars() != 1) ||
+               escape_str->numchars() > 1)))
+      {
+        my_error(ER_WRONG_ARGUMENTS,MYF(0),"ESCAPE");
+        return TRUE;
+      }
+
       if (use_mb(cmp.cmp_collation.collation))
       {
         CHARSET_INFO *cs= escape_str->charset();

sql/item_cmpfunc.h

@@ -985,13 +985,16 @@ class Item_func_like :public Item_bool_func2
   enum { alphabet_size = 256 };
 
   Item *escape_item;
+  
+  bool escape_used_in_parsing;
 
 public:
   int escape;
 
-  Item_func_like(Item *a,Item *b, Item *escape_arg)
+  Item_func_like(Item *a,Item *b, Item *escape_arg, bool escape_used)
     :Item_bool_func2(a,b), canDoTurboBM(FALSE), pattern(0), pattern_len(0), 
-     bmGs(0), bmBc(0), escape_item(escape_arg) {}
+     bmGs(0), bmBc(0), escape_item(escape_arg),
+     escape_used_in_parsing(escape_used) {}
   longlong val_int();
   enum Functype functype() const { return LIKE_FUNC; }
   optimize_type select_optimize() const;

sql/sql_help.cc

@@ -599,7 +599,8 @@ SQL_SELECT *prepare_select_for_name(THD *thd, const char *mask, uint mlen,
 {
   Item *cond= new Item_func_like(new Item_field(pfname),
 				 new Item_string(mask,mlen,pfname->charset()),
-				 new Item_string("\\",1,&my_charset_latin1));
+				 new Item_string("\\",1,&my_charset_latin1),
+                                 FALSE);
   if (thd->is_fatal_error)
     return 0;					// OOM
   return prepare_simple_select(thd, cond, table, error);

sql/sql_lex.cc

@@ -175,6 +175,7 @@ void lex_start(THD *thd, uchar *buf,uint length)
   lex->spcont= NULL;
   lex->proc_list.first= 0;
   lex->query_tables_own_last= 0;
+  lex->escape_used= FALSE;
 
   if (lex->sroutines.records)
     my_hash_reset(&lex->sroutines);

sql/sql_lex.h

@@ -894,6 +894,8 @@ typedef struct st_lex
     during replication ("LOCAL 'filename' REPLACE INTO" part).
   */
   uchar *fname_start, *fname_end;
+  
+  bool escape_used;
 
   st_lex();
 

sql/sql_yacc.yy

@@ -4314,9 +4314,9 @@ predicate:
 	  { $$= new Item_func_eq(new Item_func_soundex($1),
 				 new Item_func_soundex($4)); }
 	| bit_expr LIKE simple_expr opt_escape
-          { $$= new Item_func_like($1,$3,$4); }
+          { $$= new Item_func_like($1,$3,$4,Lex->escape_used); }
 	| bit_expr not LIKE simple_expr opt_escape
-          { $$= new Item_func_not(new Item_func_like($1,$4,$5)); }
+          { $$= new Item_func_not(new Item_func_like($1,$4,$5, Lex->escape_used)); }
 	| bit_expr REGEXP bit_expr	{ $$= new Item_func_regex($1,$3); }
 	| bit_expr not REGEXP bit_expr
           { $$= negate_expression(YYTHD, new Item_func_regex($1,$4)); }
@@ -5678,10 +5678,14 @@ having_clause:
 	;
 
 opt_escape:
-	ESCAPE_SYM simple_expr { $$= $2; }
+	ESCAPE_SYM simple_expr 
+          {
+            Lex->escape_used= TRUE;
+            $$= $2;
+          }
 	| /* empty */
           {
-
+            Lex->escape_used= FALSE;
             $$= ((YYTHD->variables.sql_mode & MODE_NO_BACKSLASH_ESCAPES) ?
 		 new Item_string("", 0, &my_charset_latin1) :
                  new Item_string("\\", 1, &my_charset_latin1));