Re: one of those annoying little things

["Matthew R. Wilson" <mwilson@mattwilson.org>]

Hi Dennis and Xi,

On 08.24.2022 13:20, Xi Ruoyao via Gcc-help wrote:
>On Wed, 2022-08-24 at 00:21 -0400, Dennis Clarke via Gcc-help wrote:
>>      Not sure who else have been doing bootstraps on machines wherein the
>> common sense thing to do is protect the source tree. What I mean is that
>> I extract the gcc 12.2.0 tarball of joy as the root user.
>> 
>> mkdir: .am388: Permission denied
>> ../../../gcc-12.2.0/mpfr/doc/mpfr.info: Permission denied
>
>> Turns out, wild, but that directory for the mpfr doc stuff has files
>> that no user has rights to other than root. That has to be a bug right?
>> Could be the mpfr guys but hey this seems weird.
>
>In MPFR Makefile.in there is:
>
>$(srcdir)/mpfr.info: mpfr.texi $(mpfr_TEXINFOS)
>
>and
>
>mpfr_TEXINFOS = texinfo.tex fdl.texi
>
>So mpfr.info is only regenerated if it does not exist, or its timestamp
>is older than mpfr.texi, texinfo.tex, or fdl.texi.  This should not
>happen if you extract mpfr from a release tarball, where:
>
>2019-01-07 21:49 fdl.texi
>2020-07-10 19:59 mpfr.info
>2020-07-10 19:52 mpfr.texi
>2020-04-14 19:12 texinfo.tex
>
>We can see mpfr.info is already up-to-date so make should not regenerate
>it.
>
>Maybe your patch changed mpfr.texi (you forgot to add the URL of "[1]"
>so I cannot know :), or you've messed up the timestamp of those files
>somehow (one notable case: using "cp -r" to copy the MPFR source tree
>can reset the timestamps to current system time).

I suspect this is indeed the case.

The instructions on the MPFR patch download page
<https://www.mpfr.org/mpfr-current/> for the cumulative patch against
the 4.1.0 release explicitly tell you to use the following patch
command:

patch -N -Z -p1 < path_to_patches_file

The -Z is what's critical here: it sets the timestamps of the patched
files to the timestamps included in the patch itself.

The cumulative patch indeed patches mpfr.info and mpfr.texi; with the
correct timestamps, the patch maintains the correct sequencing of these
files so that it's a "clean" source tree that doesn't require the
documentation to be regenerated (since the patch includes the
regenerated .info output file that corresponds to the patches to the
.texi files).

If you patch without the -Z, I'm guessing you hit the condition in the
MPFR makefile that thinks you need to regenerate the documentation in
the source tree.

I have prepared a write-protected GCC source tree on a Solaris
11.4/SPARC system using the following steps, and I was then able to
perform an out-of-tree build as an unprivileged user without
encountering any permissions problems:

As root:  
                                
# mkdir -p /export/build/gcc
# cd /export/build/gcc
# curl -LO ftp://ftp.gnu.org/gnu/gcc/gcc-12.2.0/gcc-12.2.0.tar.gz
# curl -LO https://www.mpfr.org/mpfr-current/allpatches
# gtar xzf gcc-12.2.0.tar.gz
# cd gcc-12.2.0
# ./contrib/download_prerequisites            
# cd mpfr                                              
# patch -N -Z -p1 < ../../allpatches
# cd ../..         
# chown -R root:root gcc-12.2.0
# chmod -R -w gcc-12.2.0

-Matthew