# sleep.m4 serial 11

dnl Copyright (C) 2007-2020 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_SLEEP],

[

  AC_REQUIRE([gl_UNISTD_H_DEFAULTS])

  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles

  dnl We expect to see the declaration of sleep() in a header file.

  dnl Older versions of mingw have a sleep() function that is an alias to

  dnl _sleep() in MSVCRT. It has a different signature than POSIX sleep():

  dnl it takes the number of milliseconds as argument and returns void.

  dnl mingw does not declare this function.

  AC_CHECK_DECLS([sleep], , , [[#include <unistd.h>]])

  AC_CHECK_FUNCS_ONCE([sleep])

  if test $ac_cv_have_decl_sleep != yes; then

    HAVE_SLEEP=0

  else

    dnl Cygwin 1.5.x has a bug where sleep can't exceed 49.7 days.

    AC_CACHE_CHECK([for working sleep], [gl_cv_func_sleep_works],

      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[

#include <errno.h>

#include <unistd.h>

#include <signal.h>

static void

handle_alarm (int sig)

{

  if (sig != SIGALRM)

    _exit (2);

}

]], [[

    /* Failure to compile this test due to missing alarm is okay,

       since all such platforms (mingw) also lack sleep.  */

    unsigned int pentecost = 50 * 24 * 60 * 60; /* 50 days.  */

    unsigned int remaining;

    signal (SIGALRM, handle_alarm);

    alarm (1);

    remaining = sleep (pentecost);

    if (remaining > pentecost)

      return 3;

    if (remaining <= pentecost - 10)

      return 4;

    return 0;

    ]])],

      [gl_cv_func_sleep_works=yes], [gl_cv_func_sleep_works=no],

      [case "$host_os" in

                        # Guess yes on glibc systems.

         *-gnu* | gnu*) gl_cv_func_sleep_works="guessing yes" ;;

                        # Guess yes on musl systems.

         *-musl*)       gl_cv_func_sleep_works="guessing yes" ;;

                        # Guess no on native Windows.

         mingw*)        gl_cv_func_sleep_works="guessing no" ;;

                        # If we don't know, obey --enable-cross-guesses.

         *)             gl_cv_func_sleep_works="$gl_cross_guess_normal" ;;

       esac

      ])])

    case "$gl_cv_func_sleep_works" in

      *yes) ;;

      *)

        REPLACE_SLEEP=1

        ;;

    esac

  fi

])