m4/mktime.m4

   1 # serial 20
   2 dnl Copyright (C) 2002-2003, 2005-2007, 2009-2011 Free Software Foundation,
   3 dnl Inc.
   4 dnl This file is free software; the Free Software Foundation
   5 dnl gives unlimited permission to copy and/or distribute it,
   6 dnl with or without modifications, as long as this notice is preserved.
   7
   8 dnl From Jim Meyering.
   9
  10 # Redefine AC_FUNC_MKTIME, because it is no longer maintained in Autoconf.
  11 # AC_FUNC_MKTIME
  12 # --------------
  13 AC_DEFUN([AC_FUNC_MKTIME],
  14 [AC_CHECK_HEADERS_ONCE([unistd.h])
  15 AC_CHECK_FUNCS_ONCE([alarm])
  16 AC_REQUIRE([gl_MULTIARCH])
  17 if test $APPLE_UNIVERSAL_BUILD = 1; then
  18   # A universal build on Apple MacOS X platforms.
  19   # The test result would be 'yes' in 32-bit mode and 'no' in 64-bit mode.
  20   # But we need a configuration result that is valid in both modes.
  21   ac_cv_func_working_mktime=no
  22 fi
  23 AC_CACHE_CHECK([for working mktime], [ac_cv_func_working_mktime],
  24 [AC_RUN_IFELSE([AC_LANG_SOURCE(
  25 [[/* Test program from Paul Eggert and Tony Leneis.  */
  26 #include <limits.h>
  27 #include <stdlib.h>
  28 #include <time.h>
  29
  30 #ifdef HAVE_UNISTD_H
  31 # include <unistd.h>
  32 #endif
  33
  34 #ifndef HAVE_ALARM
  35 # define alarm(X) /* empty */
  36 #endif
  37
  38 /* Work around redefinition to rpl_putenv by other config tests.  */
  39 #undef putenv
  40
  41 static time_t time_t_max;
  42 static time_t time_t_min;
  43
  44 /* Values we'll use to set the TZ environment variable.  */
  45 static char *tz_strings[] = {
  46   (char *) 0, "TZ=GMT0", "TZ=JST-9",
  47   "TZ=EST+3EDT+2,M10.1.0/00:00:00,M2.3.0/00:00:00"
  48 };
  49 #define N_STRINGS (sizeof (tz_strings) / sizeof (tz_strings[0]))
  50
  51 /* Return 0 if mktime fails to convert a date in the spring-forward gap.
  52    Based on a problem report from Andreas Jaeger.  */
  53 static int
  54 spring_forward_gap ()
  55 {
  56   /* glibc (up to about 1998-10-07) failed this test. */
  57   struct tm tm;
  58
  59   /* Use the portable POSIX.1 specification "TZ=PST8PDT,M4.1.0,M10.5.0"
  60      instead of "TZ=America/Vancouver" in order to detect the bug even
  61      on systems that don't support the Olson extension, or don't have the
  62      full zoneinfo tables installed.  */
  63   putenv ("TZ=PST8PDT,M4.1.0,M10.5.0");
  64
  65   tm.tm_year = 98;
  66   tm.tm_mon = 3;
  67   tm.tm_mday = 5;
  68   tm.tm_hour = 2;
  69   tm.tm_min = 0;
  70   tm.tm_sec = 0;
  71   tm.tm_isdst = -1;
  72   return mktime (&tm) != (time_t) -1;
  73 }
  74
  75 static int
  76 mktime_test1 (time_t now)
  77 {
  78   struct tm *lt;
  79   return ! (lt = localtime (&now)) || mktime (lt) == now;
  80 }
  81
  82 static int
  83 mktime_test (time_t now)
  84 {
  85   return (mktime_test1 (now)
  86           && mktime_test1 ((time_t) (time_t_max - now))
  87           && mktime_test1 ((time_t) (time_t_min + now)));
  88 }
  89
  90 static int
  91 irix_6_4_bug ()
  92 {
  93   /* Based on code from Ariel Faigon.  */
  94   struct tm tm;
  95   tm.tm_year = 96;
  96   tm.tm_mon = 3;
  97   tm.tm_mday = 0;
  98   tm.tm_hour = 0;
  99   tm.tm_min = 0;
 100   tm.tm_sec = 0;
 101   tm.tm_isdst = -1;
 102   mktime (&tm);
 103   return tm.tm_mon == 2 && tm.tm_mday == 31;
 104 }
 105
 106 static int
 107 bigtime_test (int j)
 108 {
 109   struct tm tm;
 110   time_t now;
 111   tm.tm_year = tm.tm_mon = tm.tm_mday = tm.tm_hour = tm.tm_min = tm.tm_sec = j;
 112   now = mktime (&tm);
 113   if (now != (time_t) -1)
 114     {
 115       struct tm *lt = localtime (&now);
 116       if (! (lt
 117              && lt->tm_year == tm.tm_year
 118              && lt->tm_mon == tm.tm_mon
 119              && lt->tm_mday == tm.tm_mday
 120              && lt->tm_hour == tm.tm_hour
 121              && lt->tm_min == tm.tm_min
 122              && lt->tm_sec == tm.tm_sec
 123              && lt->tm_yday == tm.tm_yday
 124              && lt->tm_wday == tm.tm_wday
 125              && ((lt->tm_isdst < 0 ? -1 : 0 < lt->tm_isdst)
 126                   == (tm.tm_isdst < 0 ? -1 : 0 < tm.tm_isdst))))
 127         return 0;
 128     }
 129   return 1;
 130 }
 131
 132 static int
 133 year_2050_test ()
 134 {
 135   /* The correct answer for 2050-02-01 00:00:00 in Pacific time,
 136      ignoring leap seconds.  */
 137   unsigned long int answer = 2527315200UL;
 138
 139   struct tm tm;
 140   time_t t;
 141   tm.tm_year = 2050 - 1900;
 142   tm.tm_mon = 2 - 1;
 143   tm.tm_mday = 1;
 144   tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
 145   tm.tm_isdst = -1;
 146
 147   /* Use the portable POSIX.1 specification "TZ=PST8PDT,M4.1.0,M10.5.0"
 148      instead of "TZ=America/Vancouver" in order to detect the bug even
 149      on systems that don't support the Olson extension, or don't have the
 150      full zoneinfo tables installed.  */
 151   putenv ("TZ=PST8PDT,M4.1.0,M10.5.0");
 152
 153   t = mktime (&tm);
 154
 155   /* Check that the result is either a failure, or close enough
 156      to the correct answer that we can assume the discrepancy is
 157      due to leap seconds.  */
 158   return (t == (time_t) -1
 159           || (0 < t && answer - 120 <= t && t <= answer + 120));
 160 }
 161
 162 int
 163 main ()
 164 {
 165   int result = 0;
 166   time_t t, delta;
 167   int i, j;
 168   int time_t_signed_magnitude = (time_t) ~ (time_t) 0 < (time_t) -1;
 169   int time_t_signed = ! ((time_t) 0 < (time_t) -1);
 170
 171   /* This test makes some buggy mktime implementations loop.
 172      Give up after 60 seconds; a mktime slower than that
 173      isn't worth using anyway.  */
 174   alarm (60);
 175
 176   time_t_max = (! time_t_signed
 177                 ? (time_t) -1
 178                 : ((((time_t) 1 << (sizeof (time_t) * CHAR_BIT - 2)) - 1)
 179                    * 2 + 1));
 180   time_t_min = (! time_t_signed
 181                 ? (time_t) 0
 182                 : time_t_signed_magnitude
 183                 ? ~ (time_t) 0
 184                 : ~ time_t_max);
 185
 186   delta = time_t_max / 997; /* a suitable prime number */
 187   for (i = 0; i < N_STRINGS; i++)
 188     {
 189       if (tz_strings[i])
 190         putenv (tz_strings[i]);
 191
 192       for (t = 0; t <= time_t_max - delta; t += delta)
 193         if (! mktime_test (t))
 194           result |= 1;
 195       if (! (mktime_test ((time_t) 1)
 196              && mktime_test ((time_t) (60 * 60))
 197              && mktime_test ((time_t) (60 * 60 * 24))))
 198         result |= 2;
 199
 200       for (j = 1; ; j <<= 1)
 201         if (! bigtime_test (j))
 202           result |= 4;
 203         else if (INT_MAX / 2 < j)
 204           break;
 205       if (! bigtime_test (INT_MAX))
 206         result |= 8;
 207     }
 208   if (! irix_6_4_bug ())
 209     result |= 16;
 210   if (! spring_forward_gap ())
 211     result |= 32;
 212   if (! year_2050_test ())
 213     result |= 64;
 214   return result;
 215 }]])],
 216                [ac_cv_func_working_mktime=yes],
 217                [ac_cv_func_working_mktime=no],
 218                [ac_cv_func_working_mktime=no])])
 219 if test $ac_cv_func_working_mktime = no; then
 220   AC_LIBOBJ([mktime])
 221 fi
 222 ])# AC_FUNC_MKTIME
 223
 224 AC_DEFUN([gl_FUNC_MKTIME],
 225 [
 226   AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
 227   AC_FUNC_MKTIME
 228   dnl Note: AC_FUNC_MKTIME does AC_LIBOBJ([mktime]).
 229   if test $ac_cv_func_working_mktime = no; then
 230     REPLACE_MKTIME=1
 231     gl_PREREQ_MKTIME
 232   else
 233     REPLACE_MKTIME=0
 234   fi
 235 ])
 236
 237 AC_DEFUN([gl_FUNC_MKTIME_INTERNAL], [
 238   AC_REQUIRE([gl_FUNC_MKTIME])
 239   if test $REPLACE_MKTIME = 0; then
 240     dnl BeOS has __mktime_internal in libc, but other platforms don't.
 241     AC_CHECK_FUNC([__mktime_internal],
 242       [AC_DEFINE([mktime_internal], [__mktime_internal],
 243          [Define to the real name of the mktime_internal function.])
 244       ],
 245       [dnl mktime works but it doesn't export __mktime_internal,
 246        dnl so we need to substitute our own mktime implementation.
 247        REPLACE_MKTIME=1
 248        AC_LIBOBJ([mktime])
 249        gl_PREREQ_MKTIME
 250       ])
 251   fi
 252 ])
 253
 254 # Prerequisites of lib/mktime.c.
 255 AC_DEFUN([gl_PREREQ_MKTIME],
 256 [
 257   AC_REQUIRE([AC_C_INLINE])
 258 ])