+ called, but doing so is ok. Otherwise, return zero.
+
+ The `raison d'etre' for this interface is that some systems lack
+ support for fchdir, and getcwd is not robust or as efficient.
+ So, we prefer to use the open/fchdir approach, but fall back on
+ getcwd if necessary. Some systems lack fchdir altogether: OS/2,
+ Cygwin (as of March 2003), SCO Xenix. At least SunOS 4 and Irix 5.3
+ provide the function, yet it doesn't work for partitions on which
+ auditing is enabled. */