Bug#951191: Backport /proc-based lchmod/fchmodat emulation

[Florian Weimer]

Unfortunately, this change tickles an XFS bug:

  

Bug#951191: Backport /proc-based lchmod/fchmodat emulation

[Florian Weimer]

Package: src:glibc
Version: 2.28-10

gnulib has added emilation for lchmod/fchmodat.  Since this is a
run-time test, binaries built against glibc with these patches will
not work correctly on older glibc version.  (glibc upstream did not
want symbol version markup for this change.)

The backport consists of these patches:

commit 173ec37bb2af6e30892a141d74d42db5957ddd36
Author: Florian Weimer 
Date:   Sun Feb 9 11:50:44 2020 +0100

support: Add the xlstat function

commit f6233ab412c3bebebacf65745e775e01506dd58d
Author: Florian Weimer 
Date:   Sun Feb 9 11:51:08 2020 +0100

Linux: Add io/tst-o_path-locks test

The O_PATH-based fchmodat emulation will rely on the fact that closing
an O_PATH descriptor never releases POSIX advisory locks, so this
commit adds a test case for this behavior.

commit 6b89c385d8bd0700b25bac2c2d0bebe68d5cc05d
Author: Florian Weimer 
Date:   Wed Jan 22 18:56:04 2020 +0100

io: Implement lchmod using fchmodat [BZ #14578]

commit 752dd17443e55a4535cb9e6baa4e550ede383540
Author: Florian Weimer 
Date:   Wed Jan 22 19:01:20 2020 +0100

Linux: Emulate fchmodat with AT_SYMLINK_NOFOLLOW using O_PATH [BZ #14578]

/proc/self/fd files are special and chmod on O_PATH descriptors
in that directory operates on the symbolic link itself (like lchmod).

commit 47136d6cc38c425b150dda83989303ac55f6443c
Author: Florian Weimer 
Date:   Tue Feb 11 16:22:19 2020 +0100

io: Add io/tst-lchmod covering lchmod and fchmodat