Work around a readdir bug in Darwin 7.9.0 (MacOS X 10.3.9) on HFS+

and NFS, whereby rm would not remove all files in a directory.
* src/remove.c (CONSECUTIVE_READDIR_UNLINK_THRESHOLD): Reduce to 10.
(NEED_REWIND): New macro, so that we incur the cost of the work-around
rewinddir only on afflicted systems.
* NEWS: Clarify and correct.
* tests/rm/readdir-bug: New file.  Test for the above fix.
* tests/rm/Makefile.am (TESTS): Add it.
Prompted by testing and analysis from Bruno Haible:
http://lists.gnu.org/archive/html/bug-coreutils/2006-09/msg00326.html

5 files changed, 95 insertions, 14 deletions

diff --git a/ChangeLog b/ChangeLog
index f9bb13465..7a79e0bc6 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2006-09-29  Jim Meyering  <jim@meyering.net>
+
+	Work around a readdir bug in Darwin 7.9.0 (MacOS X 10.3.9) on HFS+
+	and NFS, whereby rm would not remove all files in a directory.
+	* src/remove.c (CONSECUTIVE_READDIR_UNLINK_THRESHOLD): Reduce to 10.
+	(NEED_REWIND): New macro, so that we incur the cost of the work-around
+	rewinddir only on afflicted systems.
+	* NEWS: Clarify and correct.
+	* tests/rm/readdir-bug: New file.  Test for the above fix.
+	* tests/rm/Makefile.am (TESTS): Add it.
+	Prompted by testing and analysis from Bruno Haible:
+	http://lists.gnu.org/archive/html/bug-coreutils/2006-09/msg00326.html
+
 2006-09-28  Paul Eggert  <eggert@cs.ucla.edu>
 
 	* tests/rm/fail-eperm: Unset BASH_ENV, CDPATH, and ENV, too;
diff --git a/NEWS b/NEWS
index ce7280894..7d2eb9f8f 100644
--- a/NEWS
+++ b/NEWS
@@ -4,8 +4,9 @@ GNU coreutils NEWS                                    -*- outline -*-
 
 ** Improved robustness
 
-  rm works around a bug in Darwin 8.6.1 w/NFS that kept it from removing
-  a directory containing 188 or more entries.
+  rm works around a bug in Darwin 7.9.0 (MacOS X 10.3.9) that would
+  sometimes keep it from removing all entries in a directory on an HFS+
+  or NFS-mounted partition.
 
   sort would fail to handle very large input (around 40GB) on systems with a
   mkstemp function that returns a file descriptor limited to 32-bit offsets.
diff --git a/src/remove.c b/src/remove.c
index 24426cff9..1ea7773f7 100644
--- a/src/remove.c
+++ b/src/remove.c
@@ -50,20 +50,27 @@
 #define obstack_chunk_free free
 
 /* This is the maximum number of consecutive readdir/unlink calls that
-   can be made (with no intervening rewinddir or closedir/opendir)
-   before triggering a bug that makes readdir return NULL even though
-   some directory entries have not been processed.  The bug afflicts
-   SunOS's readdir when applied to ufs file systems and Darwin 6.5's
-   (and OSX v.10.3.8's) HFS+.  This maximum is conservative in that
-   demonstrating the problem seems to require a directory containing
-   at least 254 deletable entries (which doesn't count . and ..).
-   However, in 2006, we see that Darwin 8.6.1, using NFS has an even
-   lower limit: 188.  */
+   can be made (with no intervening rewinddir or closedir/opendir) before
+   triggering a bug that makes readdir return NULL even though some
+   directory entries have not been processed.  The bug afflicts SunOS's
+   readdir when applied to ufs file systems and Darwin 6.5's (and OSX
+   v.10.3.8's) HFS+.  This maximum is conservative in that demonstrating
+   the problem requires a directory containing at least 16 deletable
+   entries (which doesn't count . and ..).
+   This problem also affects Darwin 7.9.0 (aka MacOS X 10.3.9) on HFS+
+   and NFS-mounted file systems, but not vfat ones.  */
 enum
   {
-    CONSECUTIVE_READDIR_UNLINK_THRESHOLD = 180
+    CONSECUTIVE_READDIR_UNLINK_THRESHOLD = 10
   };
 
+#ifdef HAVE_WORKING_READDIR
+# define NEED_REWIND(readdir_unlink_count) 0
+#else
+# define NEED_REWIND(readdir_unlink_count) \
+  (CONSECUTIVE_READDIR_UNLINK_THRESHOLD <= (readdir_unlink_count))
+#endif
+
 enum Ternary
   {
     T_UNKNOWN = 2,
@@ -1139,8 +1146,7 @@ remove_cwd_entries (DIR **dirp,
 	    {
 	      /* fall through */
 	    }
-	  else if (CONSECUTIVE_READDIR_UNLINK_THRESHOLD
-		   < n_unlinked_since_opendir_or_last_rewind)
+	  else if (NEED_REWIND (n_unlinked_since_opendir_or_last_rewind))
 	    {
 	      /* Call rewinddir if we've called unlink or rmdir so many times
 		 (since the opendir or the previous rewinddir) that this
diff --git a/tests/rm/Makefile.am b/tests/rm/Makefile.am
index 958b03ef6..8fc7bcab8 100644
--- a/tests/rm/Makefile.am
+++ b/tests/rm/Makefile.am
@@ -21,6 +21,7 @@
 AUTOMAKE_OPTIONS = 1.1 gnits
 
 TESTS = \
+  readdir-bug \
   empty-inacc \
   dir-nonrecur \
   dot-rel \
diff --git a/tests/rm/readdir-bug b/tests/rm/readdir-bug
new file mode 100755
index 000000000..b15ad2012
--- /dev/null
+++ b/tests/rm/readdir-bug
@@ -0,0 +1,60 @@
+#!/bin/sh
+# Exercise the Darwin/MacOS bug worked around on 2006-09-29,
+# whereby rm would fail to remove all entries in a directory.
+
+# Copyright (C) 2006 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 2 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, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301, USA.
+
+if test "$VERBOSE" = yes; then
+  set -x
+  rm --version
+fi
+
+pwd=`pwd`
+t0=`echo "$0"|sed 's,.*/,,'`.tmp; tmp=$t0/$$
+trap 'status=$?; cd $pwd; chmod -R u+rwx $t0; rm -rf $t0 && exit $status' 0
+trap '(exit $?); exit $?' 1 2 13 15
+
+framework_failure=0
+mkdir -p $tmp || framework_failure=1
+cd $tmp || framework_failure=1
+
+# Create a directory containing many files.
+# What counts is a combination of the number of files and
+# the lengths of their names.  For details, see
+# http://lists.gnu.org/archive/html/bug-coreutils/2006-09/msg00326.html
+mkdir b || framework_failure=1
+cd b || framework_failure=1
+for i in $(seq 1 250); do
+  touch $(printf %040d $i) || framework_failure=1
+done
+cd .. || framework_failure=1
+
+if test $framework_failure = 1; then
+  echo "$0: failure in testing framework" 1>&2
+  (exit 1); exit 1
+fi
+
+fail=0
+
+# On a buggy system, this would fail with the diagnostic,
+# "cannot remove directory `b': Directory not empty"
+rm -rf b  || fail=1
+
+test -d b && fail=1
+
+(exit $fail); exit $fail