fchownat
========

POSIX specification:
 http://www.opengroup.org/onlinepubs/9699919799/functions/fchownat.html

Gnulib module: openat

Portability problems fixed by Gnulib:

  * Some platforms fail to detect trailing slash on non-directories, as in fchown(dir,"link-to-file/",uid,gid,flag): Solaris 9.

  * Some platforms mistakenly dereference symlinks when using AT_SYMLINK_NOFOLLOW: Linux kernel 2.6.17.

  * This function does not fail for an empty filename on some platforms: Linux with glibc < 2.11.

  * This function is missing on some platforms: glibc 2.3.6, MacOS X 10.5, FreeBSD 6.0, NetBSD 3.0, OpenBSD 3.8, AIX 5.1, HP-UX 11, IRIX 6.5, OSF/1 5.1, 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.  Also, the replacement may fail to change symlinks if lchown is unsupported, or fail altogether if chown is unsupported.

Portability problems not fixed by Gnulib: