summaryrefslogtreecommitdiff
path: root/m4/link.m4
blob: b0b3ff25b8c64e3a1e992585bc3e399cdd57d222 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
# link.m4 serial 9
dnl Copyright (C) 2009-2018 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_LINK],
[
  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
  AC_CHECK_FUNCS_ONCE([link])
  if test $ac_cv_func_link = no; then
    HAVE_LINK=0
  else
    AC_CACHE_CHECK([whether link obeys POSIX],
      [gl_cv_func_link_works],
      [touch conftest.a
       # Assume that if we have lstat, we can also check symlinks.
       if test $ac_cv_func_lstat = yes; then
         ln -s conftest.a conftest.lnk
       fi
       AC_RUN_IFELSE(
         [AC_LANG_PROGRAM(
           [[#include <unistd.h>
             #include <stdio.h>
           ]],
           [[int result = 0;
             if (!link ("conftest.a", "conftest.b/"))
               result |= 1;
#if HAVE_LSTAT
             if (!link ("conftest.lnk/", "conftest.b"))
               result |= 2;
             if (rename ("conftest.a", "conftest.b"))
               result |= 4;
             if (!link ("conftest.b", "conftest.lnk"))
               result |= 8;
#endif
             return result;
           ]])],
         [gl_cv_func_link_works=yes], [gl_cv_func_link_works=no],
         [case "$host_os" in
                           # Guess yes on glibc systems.
            *-gnu* | gnu*) gl_cv_func_link_works="guessing yes" ;;
                           # If we don't know, assume the worst.
            *)             gl_cv_func_link_works="guessing no" ;;
          esac
         ])
       rm -f conftest.a conftest.b conftest.lnk])
    case "$gl_cv_func_link_works" in
      *yes) ;;
      *)
        REPLACE_LINK=1
        ;;
    esac
  fi
])