File::MMagic Woes

[Anonymous Monk]

I am currently useing the File::MMagic module to get the type of file without using the standard file command.

The program runs as a server forking processes as it gets a new connection. After running the checktype_filename method once or twice the output becomes inacurate. (i.e. pdf != text/plain)
The seerver also spits out these error messages:
Bad Offset/Type at line 1. 'ng From: message/rfc822
Bad Offset/Type at line 1. 'X transcript text'
Invalid type 'video/unknown' at line 1

I can run an example programing in single exicution and it works fine each time, but in this mode it just does not work. Is there something that I am missing? or is this a baddly written module?

[Russ]

Looking in the File::MMagic source, I see this (edited for relevance):

use vars qw( $dataLoc );

sub new{
  $dataLoc = $fh->tell() if (! defined $dataLoc);
}

Question: since $dataLoc is a package-scope variable and will only be initialized once, would this cause problems when forked?

I wrote some quick and dirty sample code which does, indeed go wrong if I use File::MMagic. I assume Anonymous Monk is using use. If I require File::MMagic after the fork, it seems to work fine.

So, question to Monks-more-experienced-than-I: What happens to package variables when you fork?

Russ
Brainbench 'Most Valuable Professional' for Perl

[koolade]

I had the same problems when trying to run the script under mod_perl. The problem ends up being the same thing that Russ pointed out.

The easiest solution (other than fixing File::MMagic) is to use an external magic file when creating a new File::MMagic object. If you do this, File::MMagic won't try the buggy optimization and will read the file each time a new object is called.