Fix values printed by mysqldump for empty blob fields when

--hex-blob is used. (Bug #13318)

client/mysqldump.c

@@ -1768,6 +1768,8 @@ static void dumpTable(uint numFields, char *table)
       for (i = 0; i < mysql_num_fields(res); i++)
       {
         int is_blob;
+        ulong length= lengths[i];
+
 	if (!(field = mysql_fetch_field(res)))
 	{
 	  my_snprintf(query, QUERY_LENGTH,
@@ -1792,7 +1794,6 @@ static void dumpTable(uint numFields, char *table)
                    field->type == FIELD_TYPE_TINY_BLOB)) ? 1 : 0;
 	if (extended_insert)
 	{
-	  ulong length = lengths[i];
 	  if (i == 0)
 	    dynstr_set(&extended_row,"(");
 	  else
@@ -1882,19 +1883,19 @@ static void dumpTable(uint numFields, char *table)
 	      {
 	        print_xml_tag1(md_result_file, "\t\t", "field name=",
 			      field->name, "");
-		print_quoted_xml(md_result_file, row[i], lengths[i]);
+		print_quoted_xml(md_result_file, row[i], length);
 		fputs("</field>\n", md_result_file);
 	      }
-	      else if (opt_hex_blob && is_blob)
+	      else if (opt_hex_blob && is_blob && length)
               {
                 /* sakaik got the idea to to provide blob's in hex notation. */
-                char *ptr= row[i], *end= ptr+ lengths[i];
+                char *ptr= row[i], *end= ptr + length;
                 fputs("0x", md_result_file);
                 for (; ptr < end ; ptr++)
 		  fprintf(md_result_file, "%02X", *((uchar *)ptr));
               }
               else
-                unescape(md_result_file, row[i], lengths[i]);
+                unescape(md_result_file, row[i], length);
 	    }
 	    else
 	    {

mysql-test/r/mysqldump.result

@@ -1493,3 +1493,66 @@ insert into t2 (a, b) values (NULL, NULL),(10, NULL),(NULL, "twenty"),(30, "thir
 </database>
 </mysqldump>
 drop table t1, t2;
+create table t1 (a binary(1), b blob);
+insert into t1 values ('','');
+
+/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
+/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
+/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
+/*!40101 SET NAMES utf8 */;
+/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
+/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
+/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
+/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
+DROP TABLE IF EXISTS `t1`;
+CREATE TABLE `t1` (
+  `a` binary(1) default NULL,
+  `b` blob
+) ENGINE=MyISAM DEFAULT CHARSET=latin1;
+
+
+/*!40000 ALTER TABLE `t1` DISABLE KEYS */;
+LOCK TABLES `t1` WRITE;
+INSERT INTO `t1` VALUES ('','');
+UNLOCK TABLES;
+/*!40000 ALTER TABLE `t1` ENABLE KEYS */;
+
+/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
+/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
+/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
+/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
+/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
+/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;
+/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;
+
+
+/*!40101 SET @OLD_CHARACTER_SET_CLIENT=@@CHARACTER_SET_CLIENT */;
+/*!40101 SET @OLD_CHARACTER_SET_RESULTS=@@CHARACTER_SET_RESULTS */;
+/*!40101 SET @OLD_COLLATION_CONNECTION=@@COLLATION_CONNECTION */;
+/*!40101 SET NAMES utf8 */;
+/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
+/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
+/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
+/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
+DROP TABLE IF EXISTS `t1`;
+CREATE TABLE `t1` (
+  `a` binary(1) default NULL,
+  `b` blob
+) ENGINE=MyISAM DEFAULT CHARSET=latin1;
+
+
+/*!40000 ALTER TABLE `t1` DISABLE KEYS */;
+LOCK TABLES `t1` WRITE;
+INSERT INTO `t1` VALUES ('','');
+UNLOCK TABLES;
+/*!40000 ALTER TABLE `t1` ENABLE KEYS */;
+
+/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
+/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
+/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
+/*!40101 SET CHARACTER_SET_CLIENT=@OLD_CHARACTER_SET_CLIENT */;
+/*!40101 SET CHARACTER_SET_RESULTS=@OLD_CHARACTER_SET_RESULTS */;
+/*!40101 SET COLLATION_CONNECTION=@OLD_COLLATION_CONNECTION */;
+/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;
+
+drop table t1;

mysql-test/t/mysqldump.test

@@ -635,4 +635,13 @@ insert into t2 (a, b) values (NULL, NULL),(10, NULL),(NULL, "twenty"),(30, "thir
 --exec $MYSQL_DUMP  --skip-comments --xml --no-create-info test
 drop table t1, t2;
 
+#
+# Bug #13318: Bad result with empty field and --hex-blob
+# 
+create table t1 (a binary(1), b blob);
+insert into t1 values ('','');
+--exec $MYSQL_DUMP --skip-comments --skip-extended-insert --hex-blob test t1
+--exec $MYSQL_DUMP --skip-comments --hex-blob test t1
+drop table t1;
+
 # End of 4.1 tests