du: don't abort when a subdir is renamed during traversal

* NEWS (Bug fixes): Mention it.
* src/du.c (prev_level): Move declaration "up" to file-scope global.
(du_files): Reset prev_level to 0 upon abnormal fts_read termination.
Reported by Johathan Nieder in http://bugs.debian.org/609049
Also, improve a diagnostic.
* tests/du/move-dir-while-traversing: Test for the above.
* tests/Makefile.am (TESTS): Add it.

1 files changed, 83 insertions, 0 deletions

diff --git a/tests/du/move-dir-while-traversing b/tests/du/move-dir-while-traversing
new file mode 100755
index 000000000..fe1615c31
--- /dev/null
+++ b/tests/du/move-dir-while-traversing
@@ -0,0 +1,83 @@
+#!/bin/sh
+# Trigger a failed assertion in coreutils-8.9 and earlier.
+
+# Copyright (C) 2011 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_ du
+
+# We use a python-inotify script, so...
+python -m pyinotify -h > /dev/null \
+  || skip_ 'python inotify package not installed'
+
+# Move a directory "up" while du is processing its sub-directories.
+# While du is processing a hierarchy .../B/C/D/... this script
+# detects when du opens D/, and then moves C/ "up" one level
+# so that it is a sibling of B/.
+# Given the inherent race condition, we have to add enough "weight"
+# under D/ so that in most cases, the monitor performs the single
+# rename syscall before du finishes processing the subtree under D/.
+
+cat <<'EOF' > inotify-watch-for-dir-access.py
+#!/usr/bin/env python
+import pyinotify as pn
+import os,sys
+
+dir = sys.argv[1]
+dest_parent = os.path.dirname(os.path.dirname(dir))
+dest = os.path.join(dest_parent, os.path.basename(dir))
+
+class ProcessDir(pn.ProcessEvent):
+
+    def process_IN_OPEN(self, event):
+        os.rename(dir, dest)
+        sys.exit(0)
+
+    def process_default(self, event):
+        pass
+
+wm = pn.WatchManager()
+notifier = pn.Notifier(wm)
+wm.watch_transient_file(dir, pn.IN_OPEN, ProcessDir)
+sys.stdout.write('started\n')
+sys.stdout.flush()
+notifier.loop()
+EOF
+chmod a+x inotify-watch-for-dir-access.py
+
+long=d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z
+t=T/U
+mkdir -p $t/3/a/b/c/$long d2 || framework_failure
+timeout 6 ./inotify-watch-for-dir-access.py $t/3/a/b > start-msg &
+
+# Wait for the watcher to start...
+nonempty() { test -s start-msg || { sleep $1; return 1; }; }
+retry_delay_ nonempty .1 5
+
+# The above watches for an IN_OPEN event on $t/3/a/b,
+# and when it triggers, moves the parent, $t/3/a, up one level
+# so it's directly under $t.
+
+du -a $t d2 2> err
+# Before coreutils-8.10, du would abort.
+test $? = 1 || fail=1
+
+# check for the new diagnostic
+printf "du: fts_read failed: $t/3/a/b: No such file or directory\n" > exp \
+  || fail=1
+compare err exp || fail=1
+
+Exit $fail