# serial 27

# Copyright (C) 2001-2003, 2005, 2007, 2009-2020 Free Software Foundation, Inc.

# This file is free software; the Free Software Foundation

# gives unlimited permission to copy and/or distribute it,

# with or without modifications, as long as this notice is preserved.

dnl From Jim Meyering.

AC_DEFUN([gl_FUNC_GETTIMEOFDAY],

[

  AC_REQUIRE([gl_HEADER_SYS_TIME_H_DEFAULTS])

  AC_REQUIRE([AC_C_RESTRICT])

  AC_REQUIRE([AC_CANONICAL_HOST])

  AC_REQUIRE([gl_HEADER_SYS_TIME_H])

  AC_CHECK_FUNCS_ONCE([gettimeofday])

  gl_gettimeofday_timezone=void

  if test $ac_cv_func_gettimeofday != yes; then

    HAVE_GETTIMEOFDAY=0

  else

    gl_FUNC_GETTIMEOFDAY_CLOBBER

    AC_CACHE_CHECK([for gettimeofday with POSIX signature],

      [gl_cv_func_gettimeofday_posix_signature],

      [AC_COMPILE_IFELSE(

         [AC_LANG_PROGRAM(

            [[#include <sys/time.h>

              struct timeval c;

              int gettimeofday (struct timeval *restrict, void *restrict);

            ]],

            [[/* glibc uses struct timezone * rather than the POSIX void *

                 if _GNU_SOURCE is defined.  However, since the only portable

                 use of gettimeofday uses NULL as the second parameter, and

                 since the glibc definition is actually more typesafe, it is

                 not worth wrapping this to get a compliant signature.  */

              int (*f) (struct timeval *restrict, void *restrict)

                = gettimeofday;

              int x = f (&c, 0);

              return !(x | c.tv_sec | c.tv_usec);

            ]])],

          [gl_cv_func_gettimeofday_posix_signature=yes],

          [AC_COMPILE_IFELSE(

            [AC_LANG_PROGRAM(

              [[#include <sys/time.h>

int gettimeofday (struct timeval *restrict, struct timezone *restrict);

              ]])],

            [gl_cv_func_gettimeofday_posix_signature=almost],

            [gl_cv_func_gettimeofday_posix_signature=no])])])

    if test $gl_cv_func_gettimeofday_posix_signature = almost; then

      gl_gettimeofday_timezone='struct timezone'

    elif test $gl_cv_func_gettimeofday_posix_signature != yes; then

      REPLACE_GETTIMEOFDAY=1

    fi

    dnl If we override 'struct timeval', we also have to override gettimeofday.

    if test $REPLACE_STRUCT_TIMEVAL = 1; then

      REPLACE_GETTIMEOFDAY=1

    fi

    dnl On mingw, the original gettimeofday has only a precision of 15.6

    dnl milliseconds. So override it.

    case "$host_os" in

      mingw*) REPLACE_GETTIMEOFDAY=1 ;;

    esac

  fi

  AC_DEFINE_UNQUOTED([GETTIMEOFDAY_TIMEZONE], [$gl_gettimeofday_timezone],

    [Define this to 'void' or 'struct timezone' to match the system's

     declaration of the second argument to gettimeofday.])

])

dnl See if gettimeofday clobbers the static buffer that localtime uses

dnl for its return value.  The gettimeofday function from Mac OS X 10.0.4

dnl (i.e., Darwin 1.3.7) has this problem.

dnl

dnl If it does, then arrange to use gettimeofday and localtime only via

dnl the wrapper functions that work around the problem.

AC_DEFUN([gl_FUNC_GETTIMEOFDAY_CLOBBER],

[

 AC_REQUIRE([gl_HEADER_SYS_TIME_H])

 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles

 AC_REQUIRE([gl_LOCALTIME_BUFFER_DEFAULTS])

 AC_CACHE_CHECK([whether gettimeofday clobbers localtime buffer],

  [gl_cv_func_gettimeofday_clobber],

  [AC_RUN_IFELSE(

     [AC_LANG_PROGRAM(

        [[#include <string.h>

          #include <sys/time.h>

          #include <time.h>

          #include <stdlib.h>

        ]],

        [[

          time_t t = 0;

          struct tm *lt;

          struct tm saved_lt;

          struct timeval tv;

          lt = localtime (&t);

          saved_lt = *lt;

          gettimeofday (&tv, NULL);

          return memcmp (lt, &saved_lt, sizeof (struct tm)) != 0;

        ]])],

     [gl_cv_func_gettimeofday_clobber=no],

     [gl_cv_func_gettimeofday_clobber=yes],

     [# When cross-compiling:

      case "$host_os" in

                       # Guess all is fine on glibc systems.

        *-gnu* | gnu*) gl_cv_func_gettimeofday_clobber="guessing no" ;;

                       # Guess all is fine on musl systems.

        *-musl*)       gl_cv_func_gettimeofday_clobber="guessing no" ;;

                       # Guess no on native Windows.

        mingw*)        gl_cv_func_gettimeofday_clobber="guessing no" ;;

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

        *)             gl_cv_func_gettimeofday_clobber="$gl_cross_guess_inverted" ;;

      esac

     ])])

 case "$gl_cv_func_gettimeofday_clobber" in

   *yes)

     REPLACE_GETTIMEOFDAY=1

     AC_DEFINE([GETTIMEOFDAY_CLOBBERS_LOCALTIME], [1],

       [Define if gettimeofday clobbers the localtime buffer.])

     gl_LOCALTIME_BUFFER_NEEDED

     ;;

 esac

])

# Prerequisites of lib/gettimeofday.c.

AC_DEFUN([gl_PREREQ_GETTIMEOFDAY], [:])