Things don't work out with format `tar` and filters `none`

[jnthn]

Things don't work out with format `tar` and filters `none`

[frithnanth]

Sorry, I never tested the 'none' filter. The library supports a call to set a 'none' filter, but apparently it doesn't work using the call that sets filters by name. I patched my module to avoid calling the filter-set function if its name is 'none'; committed and pushed. As for the second problem, I didn't notice that some filters had different names when used for reading and for writing. As crazy as it may sound, the POSIX tar format is 'tar' for reading and 'v7tar', 'ustar', and 'gnutar' for writing. 'v7tar' creates the original tar format, 'ustar' creates a POSIX archive, while 'gnutar' creates the GNU version of the tar archive. I'm mulling whether document this mess or define my types and delegate my module to do the right thing. Anyway, if you have a recent libarchive you don't have to pass the 'format' and 'filter' arguments at all, because in that case the underlying library decides what format and filters are best fit for the task. Even though I don't believe it's able to understand if one wants a v7tar, a POSIX tar, or a GNU tar :-) Thank you very much for your bug report!

…

On Tue, Jan 10, 2017 at 4:38 PM, Jonathan Worthington < ***@***.***> wrote: First I tired this: my Archive::Libarchive $archive .= new( operation => LibarchiveOverwrite, file => $tar-file, format => 'tar' ); This complained that I had to specify filters together with format. I didn't want any so I tried: my Archive::Libarchive $archive .= new( operation => LibarchiveOverwrite, file => $tar-file format => 'tar', filters => ['none'] ); It then told me there was "No such format 'tar'", which is a tad odd (it's in the list of supported ones in the README). Happily, that was easily fixed by changing to gnutar: my Archive::Libarchive $archive .= new( operation => LibarchiveOverwrite, file => $tar-file format => 'gnutar', filters => ['none'] ); This told me that none is not a valid filter. I didn't figure out how to solve that, but it turned out I could apply gzip compression, so I changed it to: my Archive::Libarchive $archive .= new( operation => LibarchiveOverwrite, file => $tar-file format => 'gnutar', filters => ['gzip'] ); Which in this case was OK because I could also control the thing that would process the output to make it also ungzip it. With that, everything worked very nicely! :-) So in summary, two issues: - The bigger issue: there seems to be no way to just get a tar without any filtering (it'd also be nice if the filter parameter would default to ['none'] when that is properly supported) - The smaller issue: tar didn't seem to work, I had to use guntar Again, thanks for the module. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#2>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ADyA2GwDCbQR6mhnqdEmowMnVRN-qjliks5rQ6XYgaJpZM4LfjQM> .

-- Fernando Santagata

[jnthn]

I patched my module to avoid calling the filter-set function if its name is
'none'; committed and pushed.

Seems like a good fix; thanks.

As for the second problem, I didn't notice that some filters had different
names when used for reading and for writing.
As crazy as it may sound, the POSIX tar format is 'tar' for reading and
'v7tar', 'ustar', and 'gnutar' for writing. 'v7tar' creates the original
tar format, 'ustar' creates a POSIX archive, while 'gnutar' creates the GNU
version of the tar archive.

Aha, that explains it nicely! Thanks for taking the time to look into it. For what it's worth, the documentation mentioning this would have been sufficient for me.

[frithnanth]

I decided to add the list of formats and filters available for reading and writing operations, so programmers can choose if they want a specific tar format.