@itemize
@item
This function is missing on some platforms:
-glibc 2.3.6, MacOS X 10.3, FreeBSD 6.0, NetBSD 3.0, OpenBSD 3.8, AIX 5.1, HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 10, Cygwin, mingw, Interix 3.5, BeOS.
+glibc 2.3.6, MacOS X 10.3, FreeBSD 6.0, NetBSD 3.0, OpenBSD 3.8, AIX
+5.1, HP-UX 11, IRIX 6.5, OSF/1 5.1, Solaris 10, Cygwin 1.5.x, mingw, Interix 3.5, BeOS.
But the replacement function is not safe to be used in libraries and is not multithread-safe.
@end itemize
Portability problems not fixed by Gnulib:
@itemize
+@item
+Some platforms do not allow changing the access bits on symbolic
+links. POSIX states that @code{fchmodat(@dots{},AT_SYMLINK_NOFOLLOW)}
+may fail with @code{EOPNOTSUPP} when called on a symlink, but some
+platforms, as well as the gnulib replacement, fail for any use of
+AT_SYMLINK_NOFOLLOW even if the target was not a symlink:
+glibc, Cygwin.
@end itemize