1# double-slash-root.m4 serial 4   -*- Autoconf -*-
2dnl Copyright (C) 2006, 2008-2020 Free Software Foundation, Inc.
3dnl This file is free software; the Free Software Foundation
4dnl gives unlimited permission to copy and/or distribute it,
5dnl with or without modifications, as long as this notice is preserved.
6
7AC_DEFUN([gl_DOUBLE_SLASH_ROOT],
8[
9  AC_REQUIRE([AC_CANONICAL_HOST])
10  AC_CACHE_CHECK([whether // is distinct from /], [gl_cv_double_slash_root],
11    [ if test x"$cross_compiling" = xyes ; then
12        # When cross-compiling, there is no way to tell whether // is special
13        # short of a list of hosts.  However, the only known hosts to date
14        # that have a distinct // are Apollo DomainOS (too old to port to),
15        # Cygwin, and z/OS.  If anyone knows of another system for which // has
16        # special semantics and is distinct from /, please report it to
17        # <bug-gnulib@gnu.org>.
18        case $host in
19          *-cygwin | i370-ibm-openedition)
20            gl_cv_double_slash_root=yes ;;
21          *)
22            # Be optimistic and assume that / and // are the same when we
23            # don't know.
24            gl_cv_double_slash_root='unknown, assuming no' ;;
25        esac
26      else
27        set x `ls -di / // 2>/dev/null`
28        if test "$[2]" = "$[4]" && wc //dev/null >/dev/null 2>&1; then
29          gl_cv_double_slash_root=no
30        else
31          gl_cv_double_slash_root=yes
32        fi
33      fi])
34  if test "$gl_cv_double_slash_root" = yes; then
35    AC_DEFINE([DOUBLE_SLASH_IS_DISTINCT_ROOT], [1],
36      [Define to 1 if // is a file system root distinct from /.])
37  fi
38])
39