Although we just checked that chdir(cwd) worked, there is a
race where it could disappear while we are temporarily away.
If that happens, forcefully give up rather than proceeding
in the wrong directory.
* lib/fchdir.c (get_name): Abort on unexpected chdir failure.
* lib/rename.c (rpl_rename) [W32]: Likewise.
(rpl_rename) [RENAME_DEST_EXISTS_BUG]: Avoid one case of losing
an empty destination directory if source cannot be renamed,
although there is still possibility for failure.
* doc/posix-functions/rename.texi (rename): Document the race.
Reported by Jim Meyering.
Signed-off-by: Eric Blake <ebb9@byu.net>
This test passes on GNU/Linux, OpenBSD, and Cygwin 1.7.
Elsewhere, this test fails because of at least these bugs:
Solaris 10, cygwin 1.5.x, and mingw all mistakenly succeed on
rename("file","other/"). Solaris 9 and the gnulib replacement
for SunOS 4.1 mistakenly succeed on rename("file/","other").
Cygwin 1.5.x and mingw mistakenly succeed on rename("dir","d/.").
Cygwin 1.5.x and NetBSD 1.6 (even with the gnulib replacement)
mistakenly reduce the link count on rename("hard1","hard2").
* modules/rename-tests: New file.
* tests/test-rename.h: Likewise.
* tests/test-rename.c: Likewise.
* doc/posix-functions/rename.texi (rename): Improve documentation,
including bugs that will eventually be fixed in gnulib.
Signed-off-by: Eric Blake <ebb9@byu.net>
