GNU rm now works around Darwin 0.7.9 (MaxOS X 10.3.9) readdir bug

[Jim Meyering]

Bruno Haible <address@hidden> wrote:
>> Is there any type of file system where readdir works?
>
> Yes. It does work on vfat file systems. No readdir bug reproducible there.

FYI, I've worked around that Darwin 7.9.0 bug.
The only caveat is that when running "configure" on a buggy system,
the build directory must not be on a file system of type vfat;
there, the configure-time test would not detect the bug.
But I don't think that's a problem, since all of the systems I
know about use only NFS and hfs.  If it proves to be a problem,
I'll address it after coreutils-6.3.

2006-09-29  Jim Meyering  <address@hidden>

        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

Index: src/remove.c
===================================================================
RCS file: /fetish/cu/src/remove.c,v
retrieving revision 1.160
diff -u -r1.160 remove.c
--- src/remove.c        26 Sep 2006 20:42:43 -0000      1.160
+++ src/remove.c        29 Sep 2006 08:04:08 -0000
@@ -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 @@
            {
              /* 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
Index: NEWS
===================================================================
RCS file: /fetish/cu/NEWS,v
retrieving revision 1.431
diff -u -r1.431 NEWS
--- NEWS        26 Sep 2006 20:42:43 -0000      1.431
+++ NEWS        29 Sep 2006 08:39:12 -0000
@@ -4,8 +4,9 @@

 ** 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.
Index: tests/rm/readdir-bug
===================================================================
RCS file: tests/rm/readdir-bug
diff -N tests/rm/readdir-bug
--- /dev/null   1 Jan 1970 00:00:00 -0000
+++ tests/rm/readdir-bug        29 Sep 2006 07:57:34 -0000
@@ -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
Index: tests/rm/Makefile.am
===================================================================
RCS file: /fetish/cu/tests/rm/Makefile.am,v
retrieving revision 1.37
diff -u -r1.37 Makefile.am
--- tests/rm/Makefile.am        3 Sep 2006 07:22:09 -0000       1.37
+++ tests/rm/Makefile.am        29 Sep 2006 07:58:40 -0000
@@ -21,6 +21,7 @@
 AUTOMAKE_OPTIONS = 1.1 gnits

 TESTS = \
+  readdir-bug \
   empty-inacc \
   dir-nonrecur \
   dot-rel \