fstatat ¶POSIX specification:
https://pubs.opengroup.org/onlinepubs/9799919799/functions/fstatat.html
Portability problems fixed by Gnulib:
off_t is a 32-bit type, fstatat may
not correctly report the size of files or block devices larger than 2
GB. See Large File Support.
fstatat(fd,"file/",buf,flag) succeeds instead of
failing with ENOTDIR.
Solaris 9.
tv_sec value, tv_nsec might be in the range
−999999999..−1, representing a negative nanoseconds
offset from tv_sec. Solaris 11.4 is similar, except that
tv_sec might also be −1000000000.
Portability problems not fixed by Gnulib:
AT_EMPTY_PATH is not used:
glibc 2.7, Linux 2.6.38.
st_ino only to the low-order 32 bits of
the inode number of a socket or pipe, which thus can disagree
with the st_ino obtained by fstat:
macOS 14.
struct stat.