creating zipfile with symlinks

[Gene Heskett]

On Friday 04 March 2016 07:18:57 Larry Martell wrote:

> On Thu, Mar 3, 2016 at 10:32 PM, Larry Martell 
<larry.martell at gmail.com> wrote:
> > On Thu, Mar 3, 2016 at 4:58 PM, Chris Angelico <rosuav at gmail.com> 
wrote:
> >> On Fri, Mar 4, 2016 at 8:38 AM, MRAB <python at mrabarnett.plus.com> 
wrote:
> >>> Is it even possible to zip a link?
> >>>
> >>> A quick search came up with this:
> >>>
> >>> Are hard links possible within a zip archive?
> >>> http://stackoverflow.com/questions/8859616/are-hard-links-possible
> >>>-within-a-zip-archive
> >>
> >> Hard links are different. Symlinks are files containing the target
> >> filename, with a special mode bit set. I'm not sure if it's a
> >> standard feature of all zip archivers, but on my Debian system, I
> >> can use "zip --symlinks" to create such a zip. How that will unzip
> >> on a system that doesn't understand symlinks, I don't know.
> >>
> >> rosuav at sikorsky:~/tmp$ ls -l
> >> total 4
> >> -rw-r--r-- 1 rosuav rosuav 162 Mar  4 08:48 aaa.zip
> >> lrwxrwxrwx 1 rosuav rosuav   4 Mar  4 08:49 qwer -> asdf
> >> rosuav at sikorsky:~/tmp$ unzip -l aaa.zip
> >> Archive:  aaa.zip
> >>   Length      Date    Time    Name
> >> ---------  ---------- -----   ----
> >>         4  2016-03-04 08:45   qwer
> >> ---------                     -------
> >>         4                     1 file
> >>
> >>
> >> That's a broken symlink (there is no "asdf" in the directory), and
> >> zip and unzip are both fine with that.
> >>
> >> Now, how the Python zipfile module handles this, I don't know. The
> >> ZipInfo shows a file mode of 'lrwxrwxrwx', but when I call
> >> extract(), it comes out as a regular file. You might have to do
> >> some work manually, or else just drop to an external command with
> >> --symlinks.
> >
> > Thanks. That's what I ended up doing.
>
> Unfortunately very slow - around 8 minutes to zip a 7GB dir using the
> command line zip vs. 13 seconds with the python zipfile module.

Obviously the python version is not doing very much, or has enough python 
magic in it to be truely called magic. In any case Larry, the operative 
phrase for any of the various compression methods is TANSTAAFL.

To generate a compressed archive of 7GB of data, is going to take time, 
and I don't care what size that compressors dictionary block is. 13 
seconds is simply not a believeable figure.

I also note carefully that no one has allowed as to what exactly this 
python version does do.  Thats scary...

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>