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".

5 files changed, 41 insertions, 1 deletions

diff --git a/NEWS b/NEWS
index 59270eb0a..cb0122786 100644
--- a/NEWS
+++ b/NEWS
@@ -19,6 +19,9 @@ GNU coreutils NEWS                                    -*- outline -*-
   printing a summary to stderr.
   [bug introduced in coreutils-6.11]
 
+  df no longer requires that each command-line argument be readable
+  [bug introduced in coreutils-7.3]
+
   ls -i now prints consistent inode numbers also for mount points.
   This makes ls -i DIR less efficient on systems with dysfunctional readdir,
   because ls must stat every file in order to obtain a guaranteed-valid
diff --git a/THANKS b/THANKS
index ee18572d7..961785e0c 100644
--- a/THANKS
+++ b/THANKS
@@ -440,6 +440,7 @@ Olatunji Oluwabukunmi Ruwase        tjruwase@stanford.edu
 Olav Morkrid                        olav@funcom.com
 Ole Laursen                         olau@hardworking.dk
 Oliver Kiddle                       okiddle@yahoo.co.uk
+Olivier Fourdan                     ofourdan@redhat.com
 Ørn E. Hansen                       oehansen@daimi.aau.dk
 Oskar Liljeblad                     osk@hem.passagen.se
 Otavio Salvador                     otavio@ossystems.com.br
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;
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 0151cb091..d9ff95be4 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -300,6 +300,7 @@ TESTS =						\
   cp/src-base-dot				\
   cp/symlink-slash				\
   cp/thru-dangling				\
+  df/unreadable					\
   dd/direct					\
   dd/misc					\
   dd/not-rewound				\
diff --git a/tests/df/unreadable b/tests/df/unreadable
new file mode 100755
index 000000000..8e6002860
--- /dev/null
+++ b/tests/df/unreadable
@@ -0,0 +1,32 @@
+#!/bin/sh
+# ensure that df can handle an unreadable argument
+
+# Copyright (C) 2009 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+if test "$VERBOSE" = yes; then
+  set -x
+  df --version
+fi
+
+. $srcdir/test-lib.sh
+skip_if_root_
+
+fail=0
+touch unreadable || fail=1
+chmod a-r unreadable || fail=1
+df unreadable || fail=1
+
+Exit $fail