[pacman-dev] [PATCH] [Idea] makepkg: Extract from any file bsdtar can recognize

[Nezmer]

On Sat, May 29, 2010 at 04:31:23PM -0500, Dan McGee wrote:
> On Sat, May 29, 2010 at 4:22 PM, Andres P <aepd87 at gmail.com> wrote:
> > On Sat, May 29, 2010 at 04:17:16PM -0500, Dan McGee wrote:
> >> > If bsdtar -tf is deemed as reliable, then it should make the file(1)
> >> > check redundant, seeing that makepkg uses bsdtar to extract.
> >>
> >> Except you've now introduced the overhead of reading every archive
> >> twice which is really stupid, since 95% of files will pass the "file"
> >> check.
> >>
> > I realized that it was slower before I mentioned it:
> > ?? ??$ time for i in {1..1000}; do file -bizL neon-0.29.3-2-i686.pkg.tar.xz >/dev/null; done
> > ?? ??real ?? ??0m20.664s
> > ?? ??$ time for i in {1..1000}; do bsdtar -tf neon-0.29.3-2-i686.pkg.tar.xz >/dev/null; done
> > ?? ??real ?? ??1m16.193s
> >
> > But it greatly simplifies code :/
> >
> > It's the python dilemma...
> 
> neon? What is that, 172K? Try something that would really suck. I
> don't care if it greatly simplifies code.
> 
> dmcgee at dublin ~
> $ ll /var/cache/makepkg/src/linux-2.6.34.tar.bz2
> -rw-r--r-- 1 dmcgee wheel 65M May 16 20:46
> /var/cache/makepkg/src/linux-2.6.34.tar.bz2
> 
> This is *ONE* iteration:
> 
> dmcgee at dublin ~
> $ time bsdtar -tf /var/cache/makepkg/src/linux-2.6.34.tar.bz2 >/dev/null
> 
> real    0m51.631s
> user    0m49.940s
> sys     0m0.287s
> 

Would caching help here if "bsdtar -tf" loads the archive into memory?

> -Dan
>