Bug#1070042: libarchive: archive_entry_stat returns zero size on mips64el with _FILE_OFFSET_BITS=64

Peter Pentchev <[email protected]> Tue, 30 Apr 2024 11:12:36 +0300

Newsgroups	gmane.linux.debian.devel.bugs.general,gmane.linux.debian.ports.mips
Message-ID	<[email protected]>

On Tue, Apr 30, 2024 at 09:45:27AM +0300, Adrian Bunk wrote:
> On Mon, Apr 29, 2024 at 11:12:54AM +0200, Johannes Schauer Marin Rodrigues wrote:
> >...
> > I attached a minimal reproducer. It includes an embedded gzipped tarball with a
> > single file called "myfilename" of size 10. It works fine if _FILE_OFFSET_BITS
> > is not set but with it, it reports a wrong archive member size of zero on
> > mips64el:
> >...
> >   st_uid = 1000, st_gid = 1000, st_rdev = 0, st_pad2 = {0, 0, 10}, st_size = 0, 
> >...
> > As one can see, the size "10" is not in st_size but in the padding before the
> > st_size member. This only happens when _FILE_OFFSET_BITS=64 and only on
> > mips64el.
> > 
> > Any idea what is going on with mips64el?
> 
> The assumption that _FILE_OFFSET_BITS=64 would be a NOP on 64-bit is
> not true on MIPS, where stat and stat64 differ in padding and 
> _FILE_OFFSET_BITS=64 switches stat to the stat64 padding:
> https://sources.debian.org/src/glibc/2.36-9%2Bdeb12u4/sysdeps/unix/sysv/linux/mips/bits/struct_stat.h/#L149-L156
> 
> AC_SYS_LARGEFILE was added to e2fsprogs configure.ac 2 years ago, 
> therefore manual
>   #define _FILE_OFFSET_BITS 64
>   #define _LARGEFILE64_SOURCE 1
> should no longer be necessary for architectures where it is needed.

Yeah, I think that's what Helmut Grohne said in #1068251, I knew I had
seen it before. So IMHO the problem here is indeed not in libarchive, but,
yes, in e2fsprogs setting FILE_OFFSET_BITS=64 unconditionally.

As such, if no one objects, I think this bug should be closed and
e2fsprogs should indeed rely on AC_SYS_LARGEFILE (as libarchive already does)
instead.

Thanks everyone for tracking this down!

G'luck,
Peter

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Peter Pentchev  [email protected] [email protected] [email protected]
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