1# usleep.m4 serial 7
2dnl Copyright (C) 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
7dnl This macro intentionally does not check for select or nanosleep;
8dnl both of those modules can require external libraries.
9AC_DEFUN([gl_FUNC_USLEEP],
10[
11  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
12  dnl usleep was required in POSIX 2001, but dropped as obsolete in
13  dnl POSIX 2008; therefore, it is not always exposed in headers.
14  AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
15  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
16  AC_CHECK_FUNCS_ONCE([usleep])
17  AC_CHECK_TYPE([useconds_t], [],
18    [AC_DEFINE([useconds_t], [unsigned int], [Define to an unsigned 32-bit
19      type if <sys/types.h> lacks this type.])])
20  if test $ac_cv_func_usleep = no; then
21    HAVE_USLEEP=0
22  else
23    dnl POSIX allows implementations to reject arguments larger than
24    dnl 999999, but GNU guarantees it will work.
25    AC_CACHE_CHECK([whether usleep allows large arguments],
26      [gl_cv_func_usleep_works],
27      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
28#include <unistd.h>
29]], [[return !!usleep (1000000);]])],
30        [gl_cv_func_usleep_works=yes], [gl_cv_func_usleep_works=no],
31        [case "$host_os" in
32                          # Guess yes on glibc systems.
33           *-gnu* | gnu*) gl_cv_func_usleep_works="guessing yes" ;;
34                          # Guess yes on musl systems.
35           *-musl*)       gl_cv_func_usleep_works="guessing yes" ;;
36                          # Guess no on native Windows.
37           mingw*)        gl_cv_func_usleep_works="guessing no" ;;
38                          # If we don't know, obey --enable-cross-guesses.
39           *)             gl_cv_func_usleep_works="$gl_cross_guess_normal" ;;
40         esac
41        ])])
42    case "$gl_cv_func_usleep_works" in
43      *yes) ;;
44      *)
45        REPLACE_USLEEP=1
46        ;;
47    esac
48  fi
49])
50