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                             # Guess yes on bsd systems.
42            *bsd*)           gl_cv_func_readlink_works="guessing yes" ;;
43                             # If we don't know, obey --enable-cross-guesses.
44            *)               gl_cv_func_readlink_works="$gl_cross_guess_normal" ;;
45          esac
46         ])
47      rm -f conftest.link conftest.lnk2])
48    case "$gl_cv_func_readlink_works" in
49      *yes)
50        if test "$gl_cv_decl_readlink_works" != yes; then
51          REPLACE_READLINK=1
52        fi
53        ;;
54      *)
55        AC_DEFINE([READLINK_TRAILING_SLASH_BUG], [1], [Define to 1 if readlink
56          fails to recognize a trailing slash.])
57        REPLACE_READLINK=1
58        ;;
59    esac
60  fi
61])
62
63# Like gl_FUNC_READLINK, except prepare for separate compilation
64# (no REPLACE_READLINK, no AC_LIBOBJ).
65AC_DEFUN([gl_FUNC_READLINK_SEPARATE],
66[
67  AC_CHECK_FUNCS_ONCE([readlink])
68  gl_PREREQ_READLINK
69])
70
71# Prerequisites of lib/readlink.c.
72AC_DEFUN([gl_PREREQ_READLINK],
73[
74  :
75])
76