Re: [pmg-devel] [PATCH pmg-api] fix #4536: parse original filenames from gzip files

[Stoiko Ivanov <s.ivanov@proxmox.com>]

Thank you very much for addressing the issue and providing the patch!
technically I think this seems like a good approach!

one thing I'm not 100% sure about is, why the finding of the filename from
header is done in uncompress_file and not in __unpack_archive (where the
$newname variable is originally assigned)?
https://git.proxmox.com/?p=pmg-api.git;a=blob;f=src/PMG/Unpack.pm;h=d4fe4547ba9341a23a6841f9e24b756ed65605df;hb=HEAD#l1014

IIUC $newname is also an absolute path to a tempdir (which conveniently
also gets cleaned up on exit)

did not run any explicit tests yet - but thought I'll ask anyways.


On Fri,  3 Mar 2023 11:04:56 +0100
Leo Nunner <l.nunner@proxmox.com> wrote:

> GZIP provides the possiblity to store the original filename in the
> optional FNAME header field, which we can use for 'Match Archive
> Filename' rules.
> 
> IO::Uncompress::Gunzip is explicitly recommended for this purpose by the
> documentation on Compress::Zlib, so an additional imnport was
> introduced here.
> 
> Signed-off-by: Leo Nunner <l.nunner@proxmox.com>
> ---
>  src/PMG/Unpack.pm | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/src/PMG/Unpack.pm b/src/PMG/Unpack.pm
> index d4fe454..f79ed3f 100755
> --- a/src/PMG/Unpack.pm
> +++ b/src/PMG/Unpack.pm
> @@ -7,6 +7,7 @@ use IO::Select;
>  use Xdgmime;
>  use Compress::Zlib qw(gzopen);
>  use Compress::Bzip2 qw(bzopen);
> +use IO::Uncompress::Gunzip;
>  use File::Path;
>  use File::Temp qw(tempdir);
>  use File::Basename;
> @@ -298,6 +299,13 @@ sub uncompress_file {
>  	$maxsize = min2 ($maxsize, $filesize * $self->{maxratio});
>      }
>  
> +    if($app eq 'guzip' && (my $z = IO::Uncompress::Gunzip->new($filename))) {
> +	# the name (FNAME) field is optional in GZIP archives, so we won't
> +	# always have a value here
> +	my $header = $z->getHeaderInfo();
> +	$newname = $header->{Name} if $header->{Name};
> +    }
> +
>      $self->add_glob_mime_type ($newname);
>  
>      my $outfd;