Re: [Bug-tar] Do not fail when 'compress' is unable to provide sufficient compress ratio

[Antonio Diaz Diaz]

Paul Eggert wrote:
> If you look at the gzip source code you'll
> find a number of circumstances that will
> cause it to exit with status 2, as a warning.

It seems these warnings have been causing trouble since long ago:

http://www.gnu.org/software/tar/manual/html_node/Blocking-Factor.html#SEC157

"gzip will complain about trailing garbage if asked to uncompress a 
compressed archive on tape, there is an option to turn the message off, 
but it breaks the regularity of simply having to use 'prog -d' for 
decompression. It would be nice if gzip was silently ignoring any number 
of trailing zeros. I'll ask Jean-loup Gailly, by sending a copy of this 
message to him."

"'gzip -d -q' will be silent about the trailing zeros indeed, but will 
still return an exit status of 2 which tar reports in turn. tar might 
ignore the exit status returned, but I hate doing that, as it weakens 
the protection tar offers users against other possible problems at 
decompression time. If gzip was silently skipping trailing zeros and 
also avoiding setting the exit status in this innocuous case, that would 
solve this situation."


> This API isn't likely to change any time soon,
> I'm afraid, as gzip is fairly frozen.

Now that tar and gzip share at least one maintainer is a good moment to 
fix the warnings that can be fixed and document the rest. Currently the 
exit status of gzip is not documented in the manual (only briefly in the 
man page).


Best regards,
Antonio.