Bug#753934: Bug#750722: libsvn1: libsvn_ra_local inexplicably gains 2044KiB of zero bytes

[Niko Tyni]

On Sat, Jun 07, 2014 at 09:39:12PM -0400, James McCoy wrote:
> Control: reassign -1 binutils 2.24.51.20140604-3
> 
> On Fri, Jun 06, 2014 at 09:32:37AM +0100, RjY wrote:
> > During a recent package update I noticed libsvn1 grew a lot in
> > installed-size. Upon investigation it turned out this was:
> > 
> >     % for i in libsvn1_1.8.8-2_amd64.deb libsvn1_1.8.9-1_amd64.deb ; do dpkg -c $i ; done | grep ra_local | grep -v '^l'
> >     -rw-r--r-- root/root     39800 2014-04-01 03:20 ./usr/lib/x86_64-linux-gnu/libsvn_ra_local-1.so.1.0.0
> >     -rw-r--r-- root/root   2132856 2014-05-21 12:33 ./usr/lib/x86_64-linux-gnu/libsvn_ra_local-1.so.1.0.0
> > 
> > Why would a (relatively simple) module for local file:// url access
> > suddenly gain 2044KiB in a minor update? The extra space appears to
> > consist entirely of zero bytes, as well.
> 
> Good question.  Rebuilding 1.8.8-2 in a current sid chroot causes the
> same thing.  This seems to be caused by something in the toolchain.

> Based on my minimal knowledge of what goes into building the shared
> libraries, I'll start this off in binutils' court.

It does seem to be binutils. Bisecting one of the overgrown .so files
in the perl package (see #753934) with different versions of binutils
installed, sizes before stripping:

-rwxr-xr-x 1 niko niko 1341099 Jul  6 23:13 lib/auto/Unicode/Collate/Collate.so-binutils_2.22-8
-rwxr-xr-x 1 niko niko 1341187 Jul  6 23:22 lib/auto/Unicode/Collate/Collate.so-binutils_2.24-5
-rwxr-xr-x 1 niko niko 3434243 Jul  6 23:24 lib/auto/Unicode/Collate/Collate.so-binutils_2.24.51.20140411-2
-rwxr-xr-x 1 niko niko 3434243 Jul  6 23:35 lib/auto/Unicode/Collate/Collate.so-binutils_2.24.51.20140425-1
-rwxr-xr-x 1 niko niko 3434243 Jul  6 23:19 lib/auto/Unicode/Collate/Collate.so-binutils_2.24.51.20140604-3
-rwxr-xr-x 1 niko niko 3434243 Jul  6 23:14 lib/auto/Unicode/Collate/Collate.so-binutils_2.24.51.20140617-1

This is with just the linking step, Collate.o was the same all the time.
I was using
  rm lib/auto/Unicode/Collate/Collate.so
  make lib/auto/Unicode/Collate/Collate.so
 
which seems to execute just
  cc  -shared -Wl,-z,relro -L/usr/local/lib -fstack-protector Collate.o  -o ../../lib/auto/Unicode/Collate/Collate.so

However, the weird thing is that perl_5.18.2-4 has a smaller Collate.so
even though it was built with binutils_2.24.51.20140425-1. I see gcc
was still at 4.8 then, so maybe it needs a specific pattern that just
happens to get triggered with gcc-4.9 or something like that.

Hope this helps tracking it down,
-- 
Niko Tyni   ntyni at debian.org