#!/bin/sh
# ensure that mv doesn't first unlink its destination in one particular case

# Copyright (C) 2006-2007 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
  mv --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

# Before the fix, mv would unnecessarily unlink the destination symlink:
#   $ rm -rf s[12]; ln -s / s1; ln -s /tmp s2; strace -qe unlink /bin/mv -T s1 s2
#   unlink("s2") = 0
#
# With the fix, it doesn't call unlink:
#   $ rm -rf s[12]; ln -s / s1; ln -s /tmp s2; strace -qe unlink ./mv -T s1 s2
#   $

ln -s t1 s1 || framework_failure=1
ln -s t2 s2 || framework_failure=1

if test $framework_failure = 1; then
  echo "$0: failure in testing framework" 1>&2
  (exit 1); exit 1
fi

# Skip this test on systems without strace.
strace -V < /dev/null > ver 2>&1 || skip=1
if test "$skip" = 1; then
  echo "$0: no strace program, so skipping this test" 1>&2
  (exit 77); exit 77
fi

strace -qe unlink echo > /dev/null 2>&1 || skip=1
if test "$skip" = 1; then
  echo "$0: strace doesn't work, so skipping this test" 1>&2
  (exit 77); exit 77
fi

fail=0

strace -qe unlink mv -T s1 s2 > out 2>&1 || fail=1
$EGREP 'unlink.*"s1"' out && fail=1

# Ensure that the source, s1, is gone.
ls -dl s1 > /dev/null 2>&1 && fail=1

# Ensure that the destination, s2, contains the link from s1.
test "`readlink s2`" = t1 || fail=1

(exit $fail); exit $fail