Bug 548685

Created attachment 379162 [details]
Proposed patch

Description of problem:

  When importing large blobs (larger than the value of the mysql
  client's max_allowed_packet), extra invalid characters will be added
  to the data.

Version-Release number of selected component (if applicable):

  mysql-5.0.77-3.el5

How reproducible:

  100%

Steps to Reproduce:

  1) Increase the value of the server's max_allowed_packet option to a
     sufficiently large value by adding the following to /etc/my.cnf

       max_allowed_packet=16777216
   
     and then restarting the mysql daemon.

  2) Run the following:

       # mysql
       Welcome to the MySQL monitor.  Commands end with ; or \g.
       Your MySQL connection id is 8
       Server version: 5.0.77 Source distribution

       Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

       mysql> create database test_db;
       Query OK, 1 row affected (0.00 sec)

       mysql> use test_db;
       Database changed

       mysql> create table t1 (data longblob);
       Query OK, 0 rows affected (0.01 sec)

       mysql> insert into t1 select repeat('1', 2*1024*1024);
       Query OK, 1 row affected (0.03 sec)
       Records: 1  Duplicates: 0  Warnings: 0

       mysql> select length(data) from t1;
       +--------------+
       | length(data) |
       +--------------+
       |      2097152 | 
       +--------------+
       1 row in set (0.00 sec)
       mysql> exit
       Bye

       # mysqldump test_db t1 > test_db-t1.sql
       # mysql test_db --max_allowed_packet=1M < test_db-t1.sql
       # mysql test_db
       Reading table information for completion of table and column names
       You can turn off this feature to get a quicker startup with -A

       Welcome to the MySQL monitor.  Commands end with ; or \g.
       Your MySQL connection id is 12
       Server version: 5.0.77 Source distribution

       Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

       mysql> select length(data) from t1;
       +--------------+
       | length(data) |
       +--------------+
       |      2097153 | 
       +--------------+
       1 row in set (0.00 sec)

      mysql> 
  
Actual results:

  The entered into the table is different than what was extracted
  using the mysqldump command.

Expected results:

  The data should be the same.

Additional info:

  This is upstream MySQL bug 41486 (http://bugs.mysql.com/bug.php?id=41486).

  The attached patch is the fix for that issue backported to
  mysql-5.0.77-3.  The patch seems to have resolved the issue -- the
  built-in tests passed and the build was successful.