UNHEX() function

mysql-test/r/func_str.result

@@ -192,6 +192,15 @@ length(quote(concat(char(0),"test")))
 select hex(quote(concat(char(224),char(227),char(230),char(231),char(232),char(234),char(235))));
 hex(quote(concat(char(224),char(227),char(230),char(231),char(232),char(234),char(235))))
 27E0E3E6E7E8EAEB27
+select unhex(hex("foobar")), hex(unhex("1234567890ABCDEF")), unhex("345678");
+unhex(hex("foobar"))	hex(unhex("1234567890ABCDEF"))	unhex("345678")
+foobar	1234567890ABCDEF	4Vx
+select hex(unhex("1")), hex(unhex("12")), hex(unhex("123")), hex(unhex("1234")), hex(unhex("12345")), hex(unhex("123456"));
+hex(unhex("1"))	hex(unhex("12"))	hex(unhex("123"))	hex(unhex("1234"))	hex(unhex("12345"))	hex(unhex("123456"))
+01	12	0123	1234	012345	123456
+select length(unhex(md5("abrakadabra")));
+length(unhex(md5("abrakadabra")))
+16
 select reverse("");
 reverse("")
 

mysql-test/t/func_str.test

@@ -78,6 +78,9 @@ select quote(concat('abc\'', '\\cba'));
 select quote(1/0), quote('\0\Z');
 select length(quote(concat(char(0),"test")));
 select hex(quote(concat(char(224),char(227),char(230),char(231),char(232),char(234),char(235))));
+select unhex(hex("foobar")), hex(unhex("1234567890ABCDEF")), unhex("345678");
+select hex(unhex("1")), hex(unhex("12")), hex(unhex("123")), hex(unhex("1234")), hex(unhex("12345")), hex(unhex("123456"));
+select length(unhex(md5("abrakadabra")));
 
 #
 # Wrong usage of functions

sql/item_create.cc

@@ -426,6 +426,11 @@ Item *create_func_ucase(Item* a)
   return new Item_func_ucase(a);
 }
 
+Item *create_func_unhex(Item* a)
+{
+  return new Item_func_unhex(a);
+}
+
 Item *create_func_uuid(void)
 {
   return new Item_func_uuid();

sql/item_create.h

@@ -92,6 +92,7 @@ Item *create_func_time_format(Item *a, Item *b);
 Item *create_func_time_to_sec(Item* a);
 Item *create_func_to_days(Item* a);
 Item *create_func_ucase(Item* a);
+Item *create_func_unhex(Item* a);
 Item *create_func_uuid(void);
 Item *create_func_version(void);
 Item *create_func_weekday(Item* a);

sql/item_strfunc.cc

@@ -2231,7 +2231,7 @@ String *Item_func_hex::val_str(String *str)
   null_value=0;
   tmp_value.length(res->length()*2);
   for (from=res->ptr(), end=from+res->length(), to= (char*) tmp_value.ptr();
-       from != end ;
+       from < end ;
        from++, to+=2)
   {
     uint tmp=(uint) (uchar) *from;
@@ -2241,6 +2241,48 @@ String *Item_func_hex::val_str(String *str)
   return &tmp_value;
 }
 
+int inline hexchar_to_int(char c)
+{
+  if (c <= '9' && c >= '0')
+    return c-'0';
+  c|=32;
+  if (c <= 'f' && c >= 'a')
+    return c-'a'+10;
+  return -1;
+}
+
+String *Item_func_unhex::val_str(String *str)
+{
+  /* Convert given hex string to a binary string */
+  String *res= args[0]->val_str(str);
+  const char *from=res->ptr(), *end;
+  char *to;
+  int r;
+  if (!res || tmp_value.alloc((1+res->length())/2))
+  {
+    null_value=1;
+    return 0;
+  }
+  null_value=0;
+  tmp_value.length((1+res->length())/2);
+  to= (char*) tmp_value.ptr();
+  if (res->length() % 2)
+  {
+    *to++= r= hexchar_to_int(*from++);
+    if ((null_value= (r == -1)))
+      return 0;
+  }
+  for (end=res->ptr()+res->length(); from < end ; from+=2, to++)
+  {
+    *to= (r= hexchar_to_int(from[0])) << 4;
+    if ((null_value= (r == -1)))
+      return 0;
+    *to|= r= hexchar_to_int(from[1]);
+    if ((null_value= (r == -1)))
+      return 0;
+  }
+  return &tmp_value;
+}
 
 void Item_func_binary::print(String *str)
 {

sql/item_strfunc.h

@@ -523,6 +523,21 @@ public:
   }
 };
 
+class Item_func_unhex :public Item_str_func
+{
+  String tmp_value;
+public:
+  Item_func_unhex(Item *a) :Item_str_func(a) {}
+  const char *func_name() const { return "unhex"; }
+  String *val_str(String *);
+  void fix_length_and_dec()
+  {
+    collation.set(&my_charset_bin);
+    decimals=0;
+    max_length=(1+args[0]->max_length)/2;
+  }
+};
+
 
 class Item_func_binary :public Item_str_func
 {

sql/lex.h

@@ -671,6 +671,7 @@ static SYMBOL sql_functions[] = {
   { "UCASE",		F_SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_ucase)},
   { "UNCOMPRESS",	F_SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_uncompress)},
   { "UNCOMPRESSED_LENGTH", F_SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_uncompressed_length)},
+  { "UNHEX",		F_SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_unhex)},
   { "UNIQUE_USERS",	SYM(UNIQUE_USERS)},
   { "UNIX_TIMESTAMP",	SYM(UNIX_TIMESTAMP)},
   { "UPPER",		F_SYM(FUNC_ARG1),0,CREATE_FUNC(create_func_ucase)},