df: fix exit code and error messages with --total

When the combination of the file system options with given files or
devices does not lead to output, "df --total" would exit successfully
although it should not.

Examples:
  $ df --total --type=xfs /          # when / is not an XFS file system
  $ df --total --local -t nfs  DIR   # nfs is remote per se ...
  $ df --total -t qwerty /dev/sdb5   # typo in file system type

Furthermore, "df --total" would not print the error message "no file
systems processed" when the file argument does not exist or is otherwise
not accessible.

Example:
  $ df --total __not_exist__

These 2 bugs are present since --total was added by commit
v6.12-166-gea2887b.

* src/df.c (get_dev): Do not set file_systems_processed to true when
force_fsu is true, i.e. when the row for the "total" line is processed.
(main): Don't print totals unless we've processed a file system.
Also only print the "no FS processed" message if there was no
preceding diagnostic.
* tests/df/total-unprocessed: Add a new test.
* tests/Makefile.am: Reference the new test.
* NEWS: Mention the fix.

Improved-by: Jim Meyering

2 files changed, 42 insertions, 0 deletions

diff --git a/tests/Makefile.am b/tests/Makefile.am
index 4e7ea5835..edc04b4fb 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -375,6 +375,7 @@ TESTS =						\
   df/header					\
   df/df-P					\
   df/unreadable					\
+  df/total-unprocessed				\
   dd/direct					\
   dd/misc					\
   dd/nocache					\
diff --git a/tests/df/total-unprocessed b/tests/df/total-unprocessed
new file mode 100755
index 000000000..9742591f7
--- /dev/null
+++ b/tests/df/total-unprocessed
@@ -0,0 +1,41 @@
+#!/bin/sh
+# Ensure that df exits non-Zero and writes an error message when
+# --total is used but no file system has been processed.
+
+# Copyright (C) 2012 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/>.
+
+. "${srcdir=.}/init.sh"; path_prepend_ ../src
+print_ver_ df
+
+cat <<\EOF > exp || framework_failure_
+df: no file systems processed
+EOF
+
+# The following simply finds no match for the combination
+# of the options --local and FS-type nfs together with the
+# argument ".". It must exit non-Zero nonetheless.
+df --local -t nfs --total "." 2>out && fail=1
+compare exp out || fail=1
+
+cat <<\EOF > exp || framework_failure_
+df: '_does_not_exist_': No such file or directory
+EOF
+
+# Ensure that df writes the error message also in the following case.
+df --total _does_not_exist_ 2>out && fail=1
+compare exp out || fail=1
+
+Exit $fail