referent, there is no risk of data loss, since the symlink will
typically still point to one of the hard links.
+ "mv A B" could succeed, yet A would remain. This would happen only when
+ both A and B were hard links to the same symlink, and with a kernel for
+ which rename("A","B") does nothing and returns 0 (POSIX mandates this
+ surprising rename no-op behavior). Now, mv handles this case by skipping
+ the usually-useless rename and simply unlinking A.
+
* Noteworthy changes in release 8.15 (2012-01-06) [stable]
same_link = same;
/* If both the source and destination files are symlinks (and we'll
- know this here IFF preserving symlinks), then it's ok -- as long
- as they are distinct. */
+ know this here IFF preserving symlinks), then it's usually ok
+ when they are distinct. */
if (S_ISLNK (src_sb->st_mode) && S_ISLNK (dst_sb->st_mode))
- return ! same_name (src_name, dst_name);
+ {
+ bool sn = same_name (src_name, dst_name);
+ if ( ! sn)
+ {
+ /* It's fine when we're making any type of backup. */
+ if (x->backup_type != no_backups)
+ return true;
+
+ /* Here we have two symlinks that are hard-linked together,
+ and we're not making backups. In this unusual case, simply
+ returning true would lead to mv calling "rename(A,B)",
+ which would do nothing and return 0. I.e., A would
+ not be removed. Hence, the solution is to tell the
+ caller that all it must do is unlink A and return. */
+ if (same_link)
+ {
+ *unlink_src = true;
+ *return_now = true;
+ return true;
+ }
+ }
+
+ return ! sn;
+ }
src_sb_link = src_sb;
dst_sb_link = dst_sb;
--- /dev/null
+#!/bin/sh
+# Demonstrate that when moving a symlink onto a hardlink-to-that-symlink, the
+# source symlink is removed. Depending on your kernel (e.g., Linux, Solaris,
+# but not NetBSD), prior to coreutils-8.16, the mv would successfully perform
+# a no-op. I.e., surprisingly, mv s1 s2 would succeed, yet fail to remove s1.
+
+# Copyright (C) 2012 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_ mv
+
+# Create a file f, and a symlink s1 to that file.
+touch f || framework_failure_
+ln -s f s2 || framework_failure_
+
+for opt in '' --backup; do
+
+ # Attempt to create a hard link to that symlink.
+ # On some systems, it's not possible: they create a hard link to the referent.
+ ln s2 s1 || framework_failure_
+
+ # If s1 is not a symlink, skip this test.
+ test -h s1 \
+ || skip_ your kernel or file system cannot create a hard link to a symlink
+
+ mv $opt s1 s2 > out 2>&1 || fail=1
+ compare /dev/null out || fail=1
+
+ # Ensure that s1 is gone.
+ test -e s1 && fail=1
+
+ if test "$opt" = --backup; then
+ # With --backup, ensure that the backup file was created.
+ ref=$(readlink s2~) || fail=1
+ test "$ref" = f || fail=1
+ else
+ # Without --backup, ensure there is no backup file.
+ test -e s2~ && fail=1
+ fi
+
+done
+
+Exit $fail