m4/gettimeofday.m4

   1 # serial 21
   2
   3 # Copyright (C) 2001-2003, 2005, 2007, 2009-2014 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([AC_C_RESTRICT])
  13   AC_REQUIRE([gl_HEADER_SYS_TIME_H])
  14   AC_REQUIRE([gl_HEADER_SYS_TIME_H_DEFAULTS])
  15   AC_CHECK_FUNCS_ONCE([gettimeofday])
  16
  17   gl_gettimeofday_timezone=void
  18   if test $ac_cv_func_gettimeofday != yes; then
  19     HAVE_GETTIMEOFDAY=0
  20   else
  21     gl_FUNC_GETTIMEOFDAY_CLOBBER
  22     AC_CACHE_CHECK([for gettimeofday with POSIX signature],
  23       [gl_cv_func_gettimeofday_posix_signature],
  24       [AC_COMPILE_IFELSE(
  25          [AC_LANG_PROGRAM(
  26             [[#include <sys/time.h>
  27               struct timeval c;
  28               int gettimeofday (struct timeval *restrict, void *restrict);
  29             ]],
  30             [[/* glibc uses struct timezone * rather than the POSIX void *
  31                  if _GNU_SOURCE is defined.  However, since the only portable
  32                  use of gettimeofday uses NULL as the second parameter, and
  33                  since the glibc definition is actually more typesafe, it is
  34                  not worth wrapping this to get a compliant signature.  */
  35               int (*f) (struct timeval *restrict, void *restrict)
  36                 = gettimeofday;
  37               int x = f (&c, 0);
  38               return !(x | c.tv_sec | c.tv_usec);
  39             ]])],
  40           [gl_cv_func_gettimeofday_posix_signature=yes],
  41           [AC_COMPILE_IFELSE(
  42             [AC_LANG_PROGRAM(
  43               [[#include <sys/time.h>
  44 int gettimeofday (struct timeval *restrict, struct timezone *restrict);
  45               ]])],
  46             [gl_cv_func_gettimeofday_posix_signature=almost],
  47             [gl_cv_func_gettimeofday_posix_signature=no])])])
  48     if test $gl_cv_func_gettimeofday_posix_signature = almost; then
  49       gl_gettimeofday_timezone='struct timezone'
  50     elif test $gl_cv_func_gettimeofday_posix_signature != yes; then
  51       REPLACE_GETTIMEOFDAY=1
  52     fi
  53     dnl If we override 'struct timeval', we also have to override gettimeofday.
  54     if test $REPLACE_STRUCT_TIMEVAL = 1; then
  55       REPLACE_GETTIMEOFDAY=1
  56     fi
  57     m4_ifdef([gl_FUNC_TZSET_CLOBBER], [
  58       gl_FUNC_TZSET_CLOBBER
  59       case "$gl_cv_func_tzset_clobber" in
  60         *yes)
  61           REPLACE_GETTIMEOFDAY=1
  62           gl_GETTIMEOFDAY_REPLACE_LOCALTIME
  63           AC_DEFINE([tzset], [rpl_tzset],
  64             [Define to rpl_tzset if the wrapper function should be used.])
  65           AC_DEFINE([TZSET_CLOBBERS_LOCALTIME], [1],
  66             [Define if tzset clobbers localtime's static buffer.])
  67           ;;
  68       esac
  69     ])
  70   fi
  71   AC_DEFINE_UNQUOTED([GETTIMEOFDAY_TIMEZONE], [$gl_gettimeofday_timezone],
  72     [Define this to 'void' or 'struct timezone' to match the system's
  73      declaration of the second argument to gettimeofday.])
  74 ])
  75
  76
  77 dnl See if gettimeofday clobbers the static buffer that localtime uses
  78 dnl for its return value.  The gettimeofday function from Mac OS X 10.0.4
  79 dnl (i.e., Darwin 1.3.7) has this problem.
  80 dnl
  81 dnl If it does, then arrange to use gettimeofday and localtime only via
  82 dnl the wrapper functions that work around the problem.
  83
  84 AC_DEFUN([gl_FUNC_GETTIMEOFDAY_CLOBBER],
  85 [
  86  AC_REQUIRE([gl_HEADER_SYS_TIME_H])
  87  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
  88
  89  AC_CACHE_CHECK([whether gettimeofday clobbers localtime buffer],
  90   [gl_cv_func_gettimeofday_clobber],
  91   [AC_RUN_IFELSE(
  92      [AC_LANG_PROGRAM(
  93         [[#include <string.h>
  94           #include <sys/time.h>
  95           #include <time.h>
  96           #include <stdlib.h>
  97         ]],
  98         [[
  99           time_t t = 0;
 100           struct tm *lt;
 101           struct tm saved_lt;
 102           struct timeval tv;
 103           lt = localtime (&t);
 104           saved_lt = *lt;
 105           gettimeofday (&tv, NULL);
 106           return memcmp (lt, &saved_lt, sizeof (struct tm)) != 0;
 107         ]])],
 108      [gl_cv_func_gettimeofday_clobber=no],
 109      [gl_cv_func_gettimeofday_clobber=yes],
 110      [# When cross-compiling:
 111       case "$host_os" in
 112                 # Guess all is fine on glibc systems.
 113         *-gnu*) gl_cv_func_gettimeofday_clobber="guessing no" ;;
 114                 # If we don't know, assume the worst.
 115         *)      gl_cv_func_gettimeofday_clobber="guessing yes" ;;
 116       esac
 117      ])])
 118
 119  case "$gl_cv_func_gettimeofday_clobber" in
 120    *yes)
 121      REPLACE_GETTIMEOFDAY=1
 122      gl_GETTIMEOFDAY_REPLACE_LOCALTIME
 123      AC_DEFINE([GETTIMEOFDAY_CLOBBERS_LOCALTIME], [1],
 124        [Define if gettimeofday clobbers the localtime buffer.])
 125      ;;
 126  esac
 127 ])
 128
 129 AC_DEFUN([gl_GETTIMEOFDAY_REPLACE_LOCALTIME], [
 130   REPLACE_GMTIME=1
 131   REPLACE_LOCALTIME=1
 132 ])
 133
 134 # Prerequisites of lib/gettimeofday.c.
 135 AC_DEFUN([gl_PREREQ_GETTIMEOFDAY], [
 136   AC_CHECK_HEADERS([sys/timeb.h])
 137   AC_CHECK_FUNCS([_ftime])
 138 ])