Bug #42959 Wrong logic in backup stream library when saving object metadata
Submitted: 18 Feb 2009 7:53 Modified: 30 Mar 2009 1:51
Reporter: Rafal Somla Email Updates:
Status: Closed Impact on me:
None 
Category:MySQL Server: Backup Severity:S3 (Non-critical)
Version: OS:Any
Assigned to: Rafal Somla CPU Architecture:Any

[18 Feb 2009 7:53] Rafal Somla
Description:
The following code from stream_v1.c, function bstream_wr_item_def() is incorrect:

  ret= bcat_get_item_create_query(cat,item,&query);
  if (ret == BSTREAM_OK) 
    flags |= BSTREAM_FLAG_HAS_CREATE_STMT;
  else if (ret == BSTREAM_ERROR) 
    goto wr_error;

  /* bcat_get_item_create_data not in use yet. */
  /*
  ret= bcat_get_item_create_data(cat,item,&data);
  if (ret == BSTREAM_OK)
    flags |= BSTREAM_FLAG_HAS_EXTRA_DATA;
  else if (ret == BSTREAM_ERROR) 
    goto wr_error;
  */

This is because, according to the documentation of bcat_get_item_*() function in stream_v1_services.h, return value BSTREAM_ERROR does not indicate an error, but lack of relevant piece of metadata. Thus, in case of BSTREAM_ERROR the code should not jump to wr_error but continue leaving this part of metadata empty.

Also, the call to bcat_get_item_create_data() should not be commented-out. This is a valid part of backup image and the library should support it, even though the extra metadata is not used now.

How to repeat:
Look at code in sql/backup/stream_v1.c around line 1640.

Suggested fix:
Replace the code with:

  ret= bcat_get_item_create_query(cat,item,&query);
  if (ret == BSTREAM_OK) 
    flags |= BSTREAM_FLAG_HAS_CREATE_STMT;

  ret= bcat_get_item_create_data(cat,item,&data);
  if (ret == BSTREAM_OK)
    flags |= BSTREAM_FLAG_HAS_EXTRA_DATA;
[18 Feb 2009 8:00] Bugs System
A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/66716

2773 Rafal Somla	2009-02-18
      Bug#42959 - Wrong logic in backup stream library when saving object metadata
      
      Fixing the logic by removing incorrect gotos. Also uncommenting the 
      call to bcat_get_item_create_data() function.
[18 Feb 2009 8:16] Rafal Somla
This is more complicated that it seemed. In the original design functions bcat_get_item_create_{query,data}() can not report errors. But this is a wrong design - there must be a way to inform that error has happened when collecting object metadata, so that an appropriate action can be taken.
[4 Mar 2009 9:48] Bugs System
A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/68190

2784 Rafal Somla	2009-03-04
      Bug#42959 - Wrong logic in backup stream library when saving object metadata
      
      Changed specification of bcat_get_item_create_*() function so that they can 
      either report error or signal that there is no data. Updated the logic in
      stream_v1.c accordingly.
[4 Mar 2009 12:55] Jørgen Løland
Good to push
[5 Mar 2009 7:23] Bugs System
A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/68314

2784 Rafal Somla	2009-03-05
      Bug#42959 - Wrong logic in backup stream library when saving object metadata
      
      Changed specifications of bcat_get_item_create_*() functions so that they
      can either report error or signal that there is no data. Updated the logic
      in stream_v1.c accordingly.
[5 Mar 2009 21:17] Chuck Bell
Patch approved.
[9 Mar 2009 16:19] Bugs System
A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/68683

2789 Rafal Somla	2009-03-09
      Bug#42959 - Wrong logic in backup stream library when saving object metadata
      
      Changed specifications of bcat_get_item_create_*() functions so that they
      can either report error or signal that there is no data. Updated the logic
      in stream_v1.c accordingly.
[10 Mar 2009 18:20] Bugs System
A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/68813

2795 Rafal Somla	2009-03-10
      Bug#42959 - Wrong logic in backup stream library when saving object metadata
      
      Changed specifications of bcat_get_item_create_*() functions so that they
      can either report error or signal that there is no data. Updated the logic
      in stream_v1.c accordingly.
[11 Mar 2009 6:28] Rafal Somla
Pushed to mysql-6.0-backup tree.
[26 Mar 2009 12:35] Bugs System
Pushed into 6.0.11-alpha (revid:alik@sun.com-20090326121822-pt84kzxxayzho4mn) (version source revid:charles.bell@sun.com-20090310202133-m0cab6yr4sdhxvxg) (merge vers: 6.0.11-alpha) (pib:6)
[30 Mar 2009 1:51] Paul Dubois
Noted in 6.0.11 changelog.

The MySQL Backup library had incorrect logic and error reporting for
metadata saving.