du: fix -x: don't ignore non-directory arguments

Surprise!  "du -x non-DIR" would print nothing.
Note that the problem arises only when processing a non-directory
specified on the command line.  Not surprisingly, "du -x" still
works as expected for any directory argument.

When performing its same-file-system check, du may skip an entry
only if it is at fts_level 1 or greater.  Command-line arguments
are at fts_level == 0 (FTS_ROOTLEVEL).

* src/du.c (process_file): Don't use the top-level FTS->fts_dev
when testing for --one-file-system (-x).  It happens to be valid
for directories, but it is always 0 for a non-directory.
* tests/du/one-file-system: Add tests for this.
* NEWS (Bug fixes): Mention it.
Reported by Daniel Stavrovski in http://bugs.gnu.org/10967.
Introduced by commit v8.14-95-gcfe1040.

1 files changed, 8 insertions, 1 deletions

diff --git a/src/du.c b/src/du.c
index e4e36dfea..41c953541 100644
--- a/src/du.c
+++ b/src/du.c
@@ -443,7 +443,14 @@ process_file (FTS *fts, FTSENT *ent)
               return false;
             }
 
-          if (fts->fts_options & FTS_XDEV && fts->fts_dev != sb->st_dev)
+          /* The --one-file-system (-x) option cannot exclude anything
+             specified on the command-line.  By definition, it can exclude
+             a file or directory only when its device number is different
+             from that of its just-processed parent directory, and du does
+             not process the parent of a command-line argument.  */
+          if (fts->fts_options & FTS_XDEV
+              && FTS_ROOTLEVEL < ent->fts_level
+              && fts->fts_dev != sb->st_dev)
             excluded = true;
         }