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

1 files changed, 6 insertions, 3 deletions

diff --git a/src/df.c b/src/df.c
index 5dc3d2dd0..4f3b56b25 100644
--- a/src/df.c
+++ b/src/df.c
@@ -515,7 +515,8 @@ get_dev (char const *disk, char const *mount_point,
 
   if (! file_systems_processed)
     {
-      file_systems_processed = true;
+      if (! force_fsu)
+        file_systems_processed = true;
       get_header ();
     }
 
@@ -1124,7 +1125,7 @@ main (int argc, char **argv)
   else
     get_all_entries ();
 
-  if (print_grand_total)
+  if (print_grand_total && file_systems_processed)
     {
       if (inode_format)
         grand_fsu.fsu_blocks = 1;
@@ -1133,7 +1134,9 @@ main (int argc, char **argv)
 
   print_table ();
 
-  if (! file_systems_processed)
+  /* Print the "no FS processed" diagnostic only if there was no preceding
+     diagnostic, e.g., if all have been excluded.  */
+  if (exit_status == EXIT_SUCCESS && ! file_systems_processed)
     error (EXIT_FAILURE, 0, _("no file systems processed"));
 
   exit (exit_status);