m4/ln.m4

dnl Copyright (C) 1993-2002 Free Software Foundation, Inc.
dnl This file is free software, distributed under the terms of the GNU
dnl General Public License.  As a special exception to the GNU General
dnl Public License, this file may be distributed as part of a program
dnl that contains a configuration script generated by Autoconf, under
dnl the same distribution terms as the rest of that program.

dnl From Bruno Haible, Marcus Daniels.

AC_PREREQ(2.13)

AC_DEFUN([CL_PROG_LN],
[AC_REQUIRE([CL_PROG_CP])dnl
AC_CACHE_CHECK(how to make hard links, cl_cv_prog_LN, [
rm -f conftestdata conftestfile
echo data > conftestfile
if ln conftestfile conftestdata 2>/dev/null; then
  cl_cv_prog_LN=ln
else
  cl_cv_prog_LN="$cl_cv_prog_cp"
fi
rm -f conftestdata conftestfile
])
LN="$cl_cv_prog_LN"
AC_SUBST(LN)dnl
])

AC_DEFUN([CL_PROG_LN_S],
[AC_REQUIRE([CL_PROG_LN])dnl
dnl Make a symlink if possible; otherwise try a hard link. On filesystems
dnl which support neither symlink nor hard link, use a plain copy.
AC_MSG_CHECKING(whether ln -s works)
AC_CACHE_VAL(cl_cv_prog_LN_S, [
rm -f conftestdata
if ln -s X conftestdata 2>/dev/null; then
  cl_cv_prog_LN_S="ln -s"
else
  cl_cv_prog_LN_S="$cl_cv_prog_LN"
fi
rm -f conftestdata
])dnl
if test "$cl_cv_prog_LN_S" = "ln -s"; then
  AC_MSG_RESULT(yes)
else
  AC_MSG_RESULT(no)
fi
LN_S="$cl_cv_prog_LN_S"
AC_SUBST(LN_S)dnl
])

AC_DEFUN([CL_PROG_HLN],
[AC_REQUIRE([CL_PROG_LN_S])dnl
dnl SVR4 "ln" makes hard links to symbolic links, instead of resolving the
dnl symbolic link. To avoid this, use the "hln" program.
AC_CACHE_CHECK(how to make hard links to symlinks, cl_cv_prog_hln, [
cl_cv_prog_hln="ln"
if test "$cl_cv_prog_LN_S" = "ln -s"; then
echo "blabla" > conftest.x
ln -s conftest.x conftest.y
ln conftest.y conftest.z 2>&AC_FD_CC
rm -f conftest.x
if cat conftest.z > /dev/null 2>&1 ; then
  # ln is usable.
  cl_cv_prog_hln="ln"
else
  # conftest.z is a symbolic link to the non-existent conftest.x
  cl_cv_prog_hln="hln"
fi
else
# If there are no symbolic links, the problem cannot occur.
cl_cv_prog_hln="ln"
fi
rm -f conftest*
])
HLN="$cl_cv_prog_hln"
AC_SUBST(HLN)dnl
])