gnulib/import/m4/gettimeofday.m4

   1 # serial 27
   2
   3 # Copyright (C) 2001-2003, 2005, 2007, 2009-2019 Free Software Foundation, Inc.
   4 # This file is free software; the Free Software Foundation
   5 # gives unlimited permission to copy and/or distribute it,
   6 # with or without modifications, as long as this notice is preserved.
   7
   8 dnl From Jim Meyering.
   9
  10 AC_DEFUN([gl_FUNC_GETTIMEOFDAY],
  11 [
  12   AC_REQUIRE([gl_HEADER_SYS_TIME_H_DEFAULTS])
  13   AC_REQUIRE([AC_C_RESTRICT])
  14   AC_REQUIRE([AC_CANONICAL_HOST])
  15   AC_REQUIRE([gl_HEADER_SYS_TIME_H])
  16   AC_CHECK_FUNCS_ONCE([gettimeofday])
  17
  18   gl_gettimeofday_timezone=void
  19   if test $ac_cv_func_gettimeofday != yes; then
  20     HAVE_GETTIMEOFDAY=0
  21   else
  22     gl_FUNC_GETTIMEOFDAY_CLOBBER
  23     AC_CACHE_CHECK([for gettimeofday with POSIX signature],
  24       [gl_cv_func_gettimeofday_posix_signature],
  25       [AC_COMPILE_IFELSE(
  26          [AC_LANG_PROGRAM(
  27             [[#include <sys/time.h>
  28               struct timeval c;
  29               int gettimeofday (struct timeval *restrict, void *restrict);
  30             ]],
  31             [[/* glibc uses struct timezone * rather than the POSIX void *
  32                  if _GNU_SOURCE is defined.  However, since the only portable
  33                  use of gettimeofday uses NULL as the second parameter, and
  34                  since the glibc definition is actually more typesafe, it is
  35                  not worth wrapping this to get a compliant signature.  */
  36               int (*f) (struct timeval *restrict, void *restrict)
  37                 = gettimeofday;
  38               int x = f (&c, 0);
  39               return !(x | c.tv_sec | c.tv_usec);
  40             ]])],
  41           [gl_cv_func_gettimeofday_posix_signature=yes],
  42           [AC_COMPILE_IFELSE(
  43             [AC_LANG_PROGRAM(
  44               [[#include <sys/time.h>
  45 int gettimeofday (struct timeval *restrict, struct timezone *restrict);
  46               ]])],
  47             [gl_cv_func_gettimeofday_posix_signature=almost],
  48             [gl_cv_func_gettimeofday_posix_signature=no])])])
  49     if test $gl_cv_func_gettimeofday_posix_signature = almost; then
  50       gl_gettimeofday_timezone='struct timezone'
  51     elif test $gl_cv_func_gettimeofday_posix_signature != yes; then
  52       REPLACE_GETTIMEOFDAY=1
  53     fi
  54     dnl If we override 'struct timeval', we also have to override gettimeofday.
  55     if test $REPLACE_STRUCT_TIMEVAL = 1; then
  56       REPLACE_GETTIMEOFDAY=1
  57     fi
  58     dnl On mingw, the original gettimeofday has only a precision of 15.6
  59     dnl milliseconds. So override it.
  60     case "$host_os" in
  61       mingw*) REPLACE_GETTIMEOFDAY=1 ;;
  62     esac
  63   fi
  64   AC_DEFINE_UNQUOTED([GETTIMEOFDAY_TIMEZONE], [$gl_gettimeofday_timezone],
  65     [Define this to 'void' or 'struct timezone' to match the system's
  66      declaration of the second argument to gettimeofday.])
  67 ])
  68
  69
  70 dnl See if gettimeofday clobbers the static buffer that localtime uses
  71 dnl for its return value.  The gettimeofday function from Mac OS X 10.0.4
  72 dnl (i.e., Darwin 1.3.7) has this problem.
  73 dnl
  74 dnl If it does, then arrange to use gettimeofday and localtime only via
  75 dnl the wrapper functions that work around the problem.
  76
  77 AC_DEFUN([gl_FUNC_GETTIMEOFDAY_CLOBBER],
  78 [
  79  AC_REQUIRE([gl_HEADER_SYS_TIME_H])
  80  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
  81  AC_REQUIRE([gl_LOCALTIME_BUFFER_DEFAULTS])
  82
  83  AC_CACHE_CHECK([whether gettimeofday clobbers localtime buffer],
  84   [gl_cv_func_gettimeofday_clobber],
  85   [AC_RUN_IFELSE(
  86      [AC_LANG_PROGRAM(
  87         [[#include <string.h>
  88           #include <sys/time.h>
  89           #include <time.h>
  90           #include <stdlib.h>
  91         ]],
  92         [[
  93           time_t t = 0;
  94           struct tm *lt;
  95           struct tm saved_lt;
  96           struct timeval tv;
  97           lt = localtime (&t);
  98           saved_lt = *lt;
  99           gettimeofday (&tv, NULL);
 100           return memcmp (lt, &saved_lt, sizeof (struct tm)) != 0;
 101         ]])],
 102      [gl_cv_func_gettimeofday_clobber=no],
 103      [gl_cv_func_gettimeofday_clobber=yes],
 104      [# When cross-compiling:
 105       case "$host_os" in
 106                        # Guess all is fine on glibc systems.
 107         *-gnu* | gnu*) gl_cv_func_gettimeofday_clobber="guessing no" ;;
 108                        # Guess all is fine on musl systems.
 109         *-musl*)       gl_cv_func_gettimeofday_clobber="guessing no" ;;
 110                        # Guess no on native Windows.
 111         mingw*)        gl_cv_func_gettimeofday_clobber="guessing no" ;;
 112                        # If we don't know, obey --enable-cross-guesses.
 113         *)             gl_cv_func_gettimeofday_clobber="$gl_cross_guess_inverted" ;;
 114       esac
 115      ])])
 116
 117  case "$gl_cv_func_gettimeofday_clobber" in
 118    *yes)
 119      REPLACE_GETTIMEOFDAY=1
 120      AC_DEFINE([GETTIMEOFDAY_CLOBBERS_LOCALTIME], [1],
 121        [Define if gettimeofday clobbers the localtime buffer.])
 122      gl_LOCALTIME_BUFFER_NEEDED
 123      ;;
 124  esac
 125 ])
 126
 127 # Prerequisites of lib/gettimeofday.c.
 128 AC_DEFUN([gl_PREREQ_GETTIMEOFDAY], [:])