MDEV-13187 incorrect backslash parsing in clients

don't do backslash escapes inside backticks

client/mysql.cc

@@ -2287,7 +2287,7 @@ static bool add_line(String &buffer, char *line, ulong line_length,
       continue;
     }
 #endif
-    if (!*ml_comment && inchar == '\\' &&
+    if (!*ml_comment && inchar == '\\' && *in_string != '`' &&
         !(*in_string &&
           (mysql.server_status & SERVER_STATUS_NO_BACKSLASH_ESCAPES)))
     {

client/mysqltest.cc

@@ -6594,7 +6594,7 @@ int read_line(char *buf, int size)
 	  state= R_Q;
 	}
       }
-      have_slash= (c == '\\');
+      have_slash= (c == '\\' && last_quote != '`');
       break;
 
     case R_COMMENT:
@@ -6664,7 +6664,7 @@ int read_line(char *buf, int size)
     case R_Q:
       if (c == last_quote)
 	state= R_NORMAL;
-      else if (c == '\\')
+      else if (c == '\\' && last_quote != '`')
 	state= R_SLASH_IN_Q;
       break;
 

mysql-test/r/mysql.result

@@ -529,3 +529,31 @@ a
 +-------------------+
 
 End of tests
+create table `a1\``b1` (a int);
+show tables;
+Tables_in_test
+a1\`b1
+insert `a1\``b1` values (1),(2);
+show create table `a1\``b1`;
+Table	Create Table
+a1\`b1	CREATE TABLE `a1\``b1` (
+  `a` int(11) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+/*!40101 SET @saved_cs_client     = @@character_set_client */;
+/*!40101 SET character_set_client = utf8 */;
+CREATE TABLE `a1\``b1` (
+  `a` int(11) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1;
+/*!40101 SET character_set_client = @saved_cs_client */;
+INSERT INTO `a1\``b1` VALUES (1),(2);
+insert `a1\``b1` values (4),(5);
+show create table `a1\``b1`;
+Table	Create Table
+a1\`b1	CREATE TABLE `a1\``b1` (
+  `a` int(11) DEFAULT NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+select * from `a1\``b1`;
+a
+1
+2
+drop table `a1\``b1`;

mysql-test/t/mysql.test

@@ -618,3 +618,18 @@ EOF
 
 --echo
 --echo End of tests
+
+#
+# MDEV-13187 incorrect backslash parsing in clients
+#
+create table `a1\``b1` (a int);
+show tables;
+insert `a1\``b1` values (1),(2);
+show create table `a1\``b1`;
+--exec $MYSQL_DUMP --compact test
+--exec $MYSQL_DUMP test > $MYSQLTEST_VARDIR/tmp/bug.sql
+insert `a1\``b1` values (4),(5);
+--exec $MYSQL test < $MYSQLTEST_VARDIR/tmp/bug.sql
+show create table `a1\``b1`;
+select * from `a1\``b1`;
+drop table `a1\``b1`;