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.

4 files changed, 22 insertions, 2 deletions

diff --git a/NEWS b/NEWS
index 04c911fbd..3224b3007 100644
--- a/NEWS
+++ b/NEWS
@@ -22,6 +22,10 @@ GNU coreutils NEWS                                    -*- outline -*-
 
 ** Bug fixes
 
+  du --one-file-system (-x) would ignore any non-directory specified on
+  the command line.  For example, "touch f; du -x f" would print nothing.
+  [bug introduced in coreutils-8.14]
+
   mv now lets you move a symlink onto a same-inode destination file that
   has two or more hard links.  Before, it would reject that, saying that
   they are the same, implicitly warning you that the move would result in
diff --git a/THANKS.in b/THANKS.in
index c8dd75f85..d23f7b3b9 100644
--- a/THANKS.in
+++ b/THANKS.in
@@ -134,6 +134,7 @@ Dan Hagerty                         hag@gnu.ai.it.edu
 Dan Pascu                           dan@services.iiruc.ro
 Daniel Bergstrom                    noa@melody.se
 Daniel P. Berrangé                  berrange@redhat.com
+Daniel Stavrovski                   d@stavrovski.net
 Dániel Varga                        danielv@axelero.hu
 Danny Levinson                      danny.levinson@overture.com
 Darrel Francis                      d.francis@cheerful.com
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;
         }
 
diff --git a/tests/du/one-file-system b/tests/du/one-file-system
index f0d264ae2..110080f02 100755
--- a/tests/du/one-file-system
+++ b/tests/du/one-file-system
@@ -43,7 +43,15 @@ compare exp out || fail=1
 du -xL d > u || fail=1
 sed 's/^[0-9][0-9]*	//' u > out1
 echo d > exp1 || fail=1
-
 compare exp1 out1 || fail=1
 
+# With coreutils-8.15, "du -xs FILE" would print no output.
+touch f
+for opt in -x -xs; do
+  du $opt f > u || fail=1
+  sed 's/^[0-9][0-9]*	//' u > out2
+  echo f > exp2 || fail=1
+  compare exp2 out2 || fail=1
+done
+
 Exit $fail