df: don't fail due to an unreadable argument

* src/df.c (main): If open or fstat fails when we're trying to ensure
that all arg-partitions are automounted, fall back on using stat.
Inspired by the report and patch from Olivier Fourdan in
http://bugzilla.redhat.com/520630.
* NEWS (Bug fixes): Mention it.
* tests/df/unreadable: New test for the above.
* tests/Makefile.am (TESTS): Add df/unreadable.
The bug was introduced in coreutils-7.3 via commit dbd17157,
2009-04-28, "df: use open(2), not stat, to trigger automounting".

1 files changed, 4 insertions, 1 deletions

diff --git a/src/df.c b/src/df.c
index 787fcde21..86fd0e32e 100644
--- a/src/df.c
+++ b/src/df.c
@@ -994,8 +994,11 @@ main (int argc, char **argv)
       stats = xnmalloc (argc - optind, sizeof *stats);
       for (i = optind; i < argc; ++i)
         {
+          /* Prefer to open with O_NOCTTY and use fstat, but fall back
+             on using "stat", in case the file is unreadable.  */
           int fd = open (argv[i], O_RDONLY | O_NOCTTY);
-          if (fd < 0 || fstat (fd, &stats[i - optind]))
+          if ((fd < 0 || fstat (fd, &stats[i - optind]))
+              && stat (argv[i], &stats[i - optind]))
             {
               error (0, errno, "%s", quote (argv[i]));
               exit_status = EXIT_FAILURE;