[PATCH] fdopendir: detect FreeBSD bug

[Eric Blake]

FreeBSD fdopendir(fd) always consumes fd, even if it fails with
ENOTDIR.  The code that works around the GNU Hurd bug also fixes this;
we just need to detect it.

* m4/fdopendir.m4 (gl_FUNC_FDOPENDIR): Detect bug.
* doc/posix-functions/fdopendir.texi (fdopendir): Document it.
Reported by Jim Meyering.

Signed-off-by: Eric Blake <address@hidden>
---

Easier than I thought.

 ChangeLog                          |    6 ++++++
 doc/posix-functions/fdopendir.texi |    4 ++++
 m4/fdopendir.m4                    |   12 ++++++++----
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 3026c15..e4932ea 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2011-02-04  Eric Blake  <address@hidden>
+
+       fdopendir: detect FreeBSD bug
+       * m4/fdopendir.m4 (gl_FUNC_FDOPENDIR): Detect bug.
+       * doc/posix-functions/fdopendir.texi (fdopendir): Document it.
+
 2011-02-04  Bruno Haible  <address@hidden>

        wcsnrtombs: Prepare for new module wwcsnrtombs.
diff --git a/doc/posix-functions/fdopendir.texi 
b/doc/posix-functions/fdopendir.texi
index 92f0a43..8b8a51e 100644
--- a/doc/posix-functions/fdopendir.texi
+++ b/doc/posix-functions/fdopendir.texi
@@ -23,6 +23,10 @@ fdopendir
 This function does not reject non-directory file descriptors on some
 platforms:
 GNU/Hurd.
address@hidden
+This function mistakenly closes non-directory file descriptors on some
+platforms:
+FreeBSD 8.1.
 @end itemize

 Portability problems not fixed by Gnulib:
diff --git a/m4/fdopendir.m4 b/m4/fdopendir.m4
index 7ce0b5a..f192a62 100644
--- a/m4/fdopendir.m4
+++ b/m4/fdopendir.m4
@@ -1,4 +1,4 @@
-# serial 4
+# serial 5
 # See if we need to provide fdopendir.

 dnl Copyright (C) 2009-2011 Free Software Foundation, Inc.
@@ -27,12 +27,16 @@ AC_DEFUN([gl_FUNC_FDOPENDIR],
       [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
 #include <dirent.h>
 #include <fcntl.h>
+#include <unistd.h>
 #if !HAVE_DECL_FDOPENDIR
 extern DIR *fdopendir (int);
 #endif
-]], [int fd = open ("conftest.c", O_RDONLY);
-     if (fd < 0) return 2;
-     return !!fdopendir (fd);])],
+]], [int result = 0;
+     int fd = open ("conftest.c", O_RDONLY);
+     if (fd < 0) result |= 1;
+     if (fdopendir (fd)) result |= 2;
+     if (close (fd)) result |= 4;
+     return result;])],
          [gl_cv_func_fdopendir_works=yes],
          [gl_cv_func_fdopendir_works=no],
          [gl_cv_func_fdopendir_works="guessing no"])])
-- 
1.7.4