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emacs/m4/readlinkat.m4
Paul Eggert 220a9ecba1 Merge from Gnulib
This incorporates:
2018-01-01 maint: Run 'make update-copyright'
2017-12-29 Add cross-compilation results for GNU/Hurd.
2017-12-12 explicit_bzero: port to macOS + Clang 9.0.0
2017-12-31 17:21:33 -08:00

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# serial 5
# See if we need to provide readlinkat replacement.
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.
# Written by Eric Blake.
AC_DEFUN([gl_FUNC_READLINKAT],
[
AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
AC_CHECK_FUNCS_ONCE([readlinkat])
AC_REQUIRE([gl_FUNC_READLINK])
if test $ac_cv_func_readlinkat = no; then
HAVE_READLINKAT=0
else
AC_CACHE_CHECK([whether readlinkat signature is correct],
[gl_cv_decl_readlinkat_works],
[AC_COMPILE_IFELSE(
[AC_LANG_PROGRAM(
[[#include <unistd.h>
/* Check whether original declaration has correct type. */
ssize_t readlinkat (int, char const *, char *, size_t);]])],
[gl_cv_decl_readlinkat_works=yes],
[gl_cv_decl_readlinkat_works=no])])
# Assume readinkat has the same trailing slash bug as readlink,
# as is the case on Mac Os X 10.10
case "$gl_cv_func_readlink_works" in
*yes)
if test "$gl_cv_decl_readlinkat_works" != yes; then
REPLACE_READLINKAT=1
fi
;;
*)
REPLACE_READLINKAT=1
;;
esac
fi
])