1# readlink.m4 serial 15
2dnl Copyright (C) 2003, 2007, 2009-2020 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_FUNC_READLINK],
8[
9  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
10  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
11  AC_CHECK_FUNCS_ONCE([readlink])
12  if test $ac_cv_func_readlink = no; then
13    HAVE_READLINK=0
14  else
15    AC_CACHE_CHECK([whether readlink signature is correct],
16      [gl_cv_decl_readlink_works],
17      [AC_COMPILE_IFELSE(
18         [AC_LANG_PROGRAM(
19           [[#include <unistd.h>
20      /* Cause compilation failure if original declaration has wrong type.  */
21      ssize_t readlink (const char *, char *, size_t);]])],
22         [gl_cv_decl_readlink_works=yes], [gl_cv_decl_readlink_works=no])])
23    dnl Solaris 9 ignores trailing slash.
24    dnl FreeBSD 7.2 dereferences only one level of links with trailing slash.
25    AC_CACHE_CHECK([whether readlink handles trailing slash correctly],
26      [gl_cv_func_readlink_works],
27      [# We have readlink, so assume ln -s works.
28       ln -s conftest.no-such conftest.link
29       ln -s conftest.link conftest.lnk2
30       AC_RUN_IFELSE(
31         [AC_LANG_PROGRAM(
32           [[#include <unistd.h>
33]], [[char buf[20];
34      return readlink ("conftest.lnk2/", buf, sizeof buf) != -1;]])],
35         [gl_cv_func_readlink_works=yes], [gl_cv_func_readlink_works=no],
36         [case "$host_os" in
37                             # Guess yes on Linux systems.
38            linux-* | linux) gl_cv_func_readlink_works="guessing yes" ;;
39                             # Guess yes on glibc systems.
40            *-gnu* | gnu*)   gl_cv_func_readlink_works="guessing yes" ;;
41                             # If we don't know, obey --enable-cross-guesses.
42            *)               gl_cv_func_readlink_works="$gl_cross_guess_normal" ;;
43          esac
44         ])
45      rm -f conftest.link conftest.lnk2])
46    case "$gl_cv_func_readlink_works" in
47      *yes)
48        if test "$gl_cv_decl_readlink_works" != yes; then
49          REPLACE_READLINK=1
50        fi
51        ;;
52      *)
53        AC_DEFINE([READLINK_TRAILING_SLASH_BUG], [1], [Define to 1 if readlink
54          fails to recognize a trailing slash.])
55        REPLACE_READLINK=1
56        ;;
57    esac
58  fi
59])
60
61# Like gl_FUNC_READLINK, except prepare for separate compilation
62# (no REPLACE_READLINK, no AC_LIBOBJ).
63AC_DEFUN([gl_FUNC_READLINK_SEPARATE],
64[
65  AC_CHECK_FUNCS_ONCE([readlink])
66  gl_PREREQ_READLINK
67])
68
69# Prerequisites of lib/readlink.c.
70AC_DEFUN([gl_PREREQ_READLINK],
71[
72  :
73])
74