[Bug libc/29730] New: broken y2038 support in fstatat on MIPS N64

["aurelien at aurel32 dot net" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=29730

            Bug ID: 29730
           Summary: broken y2038 support in fstatat on MIPS N64
           Product: glibc
           Version: 2.35
            Status: NEW
          Severity: normal
          Priority: P1
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: aurelien at aurel32 dot net
                CC: adhemerval.zanella at linaro dot org, drepper.fsp at gmail dot com
  Target Milestone: ---
              Host: mips64el-unknown-linux-gnuabi64
            Target: mips64el-unknown-linux-gnuabi64
             Build: mips64el-unknown-linux-gnuabi64

On MIPS N64 the fstat/fstatat/lstat functions return EOVERFLOW when they are
called on files with a mtime, atime or ctime that can't be represented within a 
32-bit time_t. This should not happen as time_t is 64-bit on mips64el. This can
be reproduce for instance with:

$ touch -d 20390101 t
$ chmod +x t
chmod: cannot access 't': Value too large for defined data type
$ 

This issue has been introduced in glibc 2.35 by the following commit:

commit 6e8a0aac2f883a23efb1683b120499138f9e6021
Author: Stafford Horne <shorne@gmail.com>
Date:   Mon Jun 7 22:10:19 2021 +0900

    time: Fix overflow itimer tests on 32-bit systems

    On the port of OpenRISC I am working on and it appears the rv32 port
    we have sets __TIMESIZE == 64 && __WORDSIZE == 32.  This causes the
    size of time_t to be 8 bytes, but the tv_sec in the kernel is still 32-bit
    causing truncation.

    The truncations are unavoidable on these systems so skip the
    testing/failures by guarding with __KERNEL_OLD_TIMEVAL_MATCHES_TIMEVAL64.

    Also, futher in the tests and in other parts of code checking for time_t
    overflow does not work on 32-bit systems when time_t is 64-bit.  As
    suggested by Adhemerval, update the in_time_t_range function to assume
    32-bits by using int32_t.

    This also brings in the header for stdint.h so we can update other
    usages of __int32_t to int32_t as suggested by Adhemerval.

    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

MIPS N64 uses a 64-bit time_t, however it does not define XSTAT_IS_XSTAT64.
Therefore fstatat is different than fstatat64, and uses the default
sysdeps/unix/sysv/linux/fstatat.c implementation, which uses in_time_t_range()
with a 64-bit time_t.

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