clanscan return codes no longer provide details of errors

It looks like the executable mode code was written when clamscan used to provide rich information about errors in its return codes:

  /**
   * clamscan return values (documented from man clamscan)
   *  0 : No virus found.
   *  1 : Virus(es) found.
   * 40: Unknown option passed.
   * 50: Database initialization error.
   * 52: Not supported file type.
   * 53: Can't open directory.
   * 54: Can't open file. (ofm)
   * 55: Error reading file. (ofm)
   * 56: Can't stat input file / directory.
   * 57: Can't get absolute path name of current working directory.
   * 58: I/O error, please check your file system.
   * 62: Can't initialize logger.
   * 63: Can't create temporary files/directories (check permissions).
   * 64: Can't write to temporary directory (please specify another one).
   * 70: Can't allocate memory (calloc).
   * 71: Can't allocate memory (malloc).
   */

...the switch/case based on the return code from the executable is based on the return code being something like the above.

However, it looks like clamscan changed the way it reports errors some time ago:

Looking at the source code for the clamav project itself, the detailed error messages were present in the man page in release 0.95 (from 2009):

https://github.com/vrtadmin/clamav-devel/blob/clamav-0.95/docs/man/clams...

...but they were replaced by the catch-all return code 2 in the next release 0.96 (from 2010):

https://github.com/vrtadmin/clamav-devel/blob/clamav-0.96/docs/man/clams...

The man page now just says this:

RETURN CODES
       0 : No virus found.
       1 : Virus(es) found.
       2 : Some error(s) occured.

Therefore when something goes wrong, the module typically records very little information e.g.

Clamscan reported: [2] - unknown error

The actual output from clamscan is discarded and only the return code is logged:

  // exec:
  // The lines of text output by clamscan are assigned as an array to $output
  // The actual result of clamscan is assigned to $result:
  // 0 = clean
  // 1 = infected
  // x = unchecked
  exec($cmd, $output, $result);

  // ...snip...

      watchdog('clamav', 'Uploaded file %filename could not be scanned.  Clamscan reported: [@error_code] - @error_description', array('%filename' => $filename, '@error_code' => $result, '@error_description' => $description), WATCHDOG_WARNING);

It would probably be useful if the full $output was logged when clamscan returns 2.

It may also be an idea to provide an option to do something like try the scan again with some extra options (--verbose --debug perhaps?) and log the output of that. Alternatively just being able to pass extra options to the executable all the time would be a useful addition.

One or more patches on the way.