Fix mysqldump handling of varbinary columns

Summary:
https://bugs.mysql.com/bug.php?id=96053

8.0.13 added _binary tags to blobs in the mysqldump output. However,
memory allocated for the insert statement did not account of the 8 bytes
of the "_binary " string properly. This resulted in mysqldump writing
to memory beyond the buffer allocated for the string buffer before it
is reallocated with a new larger size.

The fix is to account for the 8 bytes of the "_binary " string during
the realloc calculation.

Reviewed By: lloyd

Differential Revision: D16088056 (facebook@5e15108)

fbshipit-source-id: 7d8cd4398f1

client/mysqldump.cc

@@ -4178,12 +4178,13 @@ static void dump_table(char *table, char *db) {
                   - In non-HEX mode we need up to 2 bytes per character,
                   plus 2 bytes for leading and trailing '\'' characters
                   and reserve 1 byte for terminating '\0'.
+                  Also we need to reserve 8 bytes for "_binary ".
                   In addition to this, for the blob type, we need to
                   reserve for the "_binary " string that gets added in
                   front of the string in the dump.
                 */
                 if (opt_hex_blob && is_blob) {
-                  dynstr_realloc_checked(&extended_row, length * 2 + 2 + 1);
+                  dynstr_realloc_checked(&extended_row, length * 2 + 8 + 2 + 1);
                   dynstr_append_checked(&extended_row, "0x");
                   extended_row.length += mysql_hex_string(
                       extended_row.str + extended_row.length, row[i], length);
@@ -4193,8 +4194,8 @@ static void dump_table(char *table, char *db) {
                   DBUG_ASSERT(extended_row.str[extended_row.length] == '\0');
                 } else {
                   dynstr_realloc_checked(
-                      &extended_row,
-                      length * 2 + 2 + 1 + (is_blob ? strlen("_binary ") : 0));
+                      &extended_row, length * 2 + 8 + 2 + 1 +
+                                         (is_blob ? strlen("_binary ") : 0));
                   if (is_blob) {
                     /*
                       inform SQL parser that this string isn't in

mysql-test/r/mysqldump-binary.result

@@ -79,3 +79,15 @@ ST_AsText(g) FROM t1;
 u='basic'	HEX(b)='EE0C6D03C34C11E5B1640026B977EB17'	HEX(blo)='EE0C6D03C34C11E5B1640026B977EB17'	HEX(g)='000000000101000000000000000000F03F000000000000F03F'	HEX(bi)='EE0C6D03C34C11E5'	ST_AsText(g)
 1	1	1	1	1	POINT(1 1)
 DROP TABLE t1;
+CREATE TABLE t1 (pk INT, v1 VARCHAR(255), v2 VARCHAR(255), v3 VARCHAR(255), v4 VARCHAR(128), v5 VARCHAR(64), v6 VARCHAR(16), v7 VARCHAR(16), v8 VARCHAR (8), v9 VARBINARY(32), v10 VARBINARY(32));
+SELECT '12345678901234567890123456789012345678901234567890' INTO @s;
+SELECT CONCAT(@s, @s, @s, @s, @s) INTO @s1;
+INSERT INTO t1 VALUES (1, @s1, @s1, @s1, SUBSTRING(@s1, 1, 128), SUBSTRING(@s1, 1, 64), SUBSTRING(@s1, 1, 16), SUBSTRING(@s1, 1, 16), SUBSTRING(@s1, 1, 8), '', 'NULL');
+CHECKSUM TABLE t1;
+Table	Checksum
+test.t1	869635727
+DROP TABLE t1;
+CHECKSUM TABLE t1;
+Table	Checksum
+test.t1	869635727
+DROP TABLE t1;

mysql-test/t/mysqldump-binary.test

@@ -72,3 +72,16 @@ ST_AsText(g) FROM t1;
 
 DROP TABLE t1;
 --remove_file $MYSQLTEST_VARDIR/tmp/bug22601255.sql
+
+# Verify mysqldump's memory buffer accounts for "_binary " properly
+CREATE TABLE t1 (pk INT, v1 VARCHAR(255), v2 VARCHAR(255), v3 VARCHAR(255), v4 VARCHAR(128), v5 VARCHAR(64), v6 VARCHAR(16), v7 VARCHAR(16), v8 VARCHAR (8), v9 VARBINARY(32), v10 VARBINARY(32));
+SELECT '12345678901234567890123456789012345678901234567890' INTO @s;
+SELECT CONCAT(@s, @s, @s, @s, @s) INTO @s1;
+INSERT INTO t1 VALUES (1, @s1, @s1, @s1, SUBSTRING(@s1, 1, 128), SUBSTRING(@s1, 1, 64), SUBSTRING(@s1, 1, 16), SUBSTRING(@s1, 1, 16), SUBSTRING(@s1, 1, 8), '', 'NULL');
+CHECKSUM TABLE t1;
+--exec $MYSQL_DUMP test t1 > $MYSQLTEST_VARDIR/tmp/bug96053.sql
+DROP TABLE t1;
+--exec $MYSQL test < $MYSQLTEST_VARDIR/tmp/bug96053.sql
+CHECKSUM TABLE t1;
+DROP TABLE t1;
+--remove_file $MYSQLTEST_VARDIR/tmp/bug96053.sql