code.delx.au - gnu-emacs/blob - m4/mktime.m4

   1 # serial 26
   2 dnl Copyright (C) 2002-2003, 2005-2007, 2009-2016 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 AC_DEFUN([gl_TIME_T_IS_SIGNED],
  11 [
  12   AC_CACHE_CHECK([whether time_t is signed],
  13     [gl_cv_time_t_is_signed],
  14     [AC_COMPILE_IFELSE(
  15        [AC_LANG_PROGRAM([[#include <time.h>
  16                           char time_t_signed[(time_t) -1 < 0 ? 1 : -1];]])],
  17        [gl_cv_time_t_is_signed=yes],
  18        [gl_cv_time_t_is_signed=no])])
  19   if test $gl_cv_time_t_is_signed = yes; then
  20     AC_DEFINE([TIME_T_IS_SIGNED], [1], [Define to 1 if time_t is signed.])
  21   fi
  22 ])
  23
  24 AC_DEFUN([gl_FUNC_MKTIME],
  25 [
  26   AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
  27   AC_REQUIRE([gl_TIME_T_IS_SIGNED])
  28
  29   dnl We don't use AC_FUNC_MKTIME any more, because it is no longer maintained
  30   dnl in Autoconf and because it invokes AC_LIBOBJ.
  31   AC_CHECK_HEADERS_ONCE([unistd.h])
  32   AC_CHECK_DECLS_ONCE([alarm])
  33   AC_REQUIRE([gl_MULTIARCH])
  34   if test $APPLE_UNIVERSAL_BUILD = 1; then
  35     # A universal build on Apple Mac OS X platforms.
  36     # The test result would be 'yes' in 32-bit mode and 'no' in 64-bit mode.
  37     # But we need a configuration result that is valid in both modes.
  38     gl_cv_func_working_mktime=no
  39   fi
  40   AC_CACHE_CHECK([for working mktime], [gl_cv_func_working_mktime],
  41     [AC_RUN_IFELSE(
  42        [AC_LANG_SOURCE(
  43 [[/* Test program from Paul Eggert and Tony Leneis.  */
  44 #include <limits.h>
  45 #include <stdlib.h>
  46 #include <time.h>
  47
  48 #ifdef HAVE_UNISTD_H
  49 # include <unistd.h>
  50 #endif
  51
  52 #if HAVE_DECL_ALARM
  53 # include <signal.h>
  54 #endif
  55
  56 /* Work around redefinition to rpl_putenv by other config tests.  */
  57 #undef putenv
  58
  59 static time_t time_t_max;
  60 static time_t time_t_min;
  61
  62 /* Values we'll use to set the TZ environment variable.  */
  63 static char *tz_strings[] = {
  64   (char *) 0, "TZ=GMT0", "TZ=JST-9",
  65   "TZ=EST+3EDT+2,M10.1.0/00:00:00,M2.3.0/00:00:00"
  66 };
  67 #define N_STRINGS (sizeof (tz_strings) / sizeof (tz_strings[0]))
  68
  69 /* Return 0 if mktime fails to convert a date in the spring-forward gap.
  70    Based on a problem report from Andreas Jaeger.  */
  71 static int
  72 spring_forward_gap ()
  73 {
  74   /* glibc (up to about 1998-10-07) failed this test. */
  75   struct tm tm;
  76
  77   /* Use the portable POSIX.1 specification "TZ=PST8PDT,M4.1.0,M10.5.0"
  78      instead of "TZ=America/Vancouver" in order to detect the bug even
  79      on systems that don't support the Olson extension, or don't have the
  80      full zoneinfo tables installed.  */
  81   putenv ("TZ=PST8PDT,M4.1.0,M10.5.0");
  82
  83   tm.tm_year = 98;
  84   tm.tm_mon = 3;
  85   tm.tm_mday = 5;
  86   tm.tm_hour = 2;
  87   tm.tm_min = 0;
  88   tm.tm_sec = 0;
  89   tm.tm_isdst = -1;
  90   return mktime (&tm) != (time_t) -1;
  91 }
  92
  93 static int
  94 mktime_test1 (time_t now)
  95 {
  96   struct tm *lt;
  97   return ! (lt = localtime (&now)) || mktime (lt) == now;
  98 }
  99
 100 static int
 101 mktime_test (time_t now)
 102 {
 103   return (mktime_test1 (now)
 104           && mktime_test1 ((time_t) (time_t_max - now))
 105           && mktime_test1 ((time_t) (time_t_min + now)));
 106 }
 107
 108 static int
 109 irix_6_4_bug ()
 110 {
 111   /* Based on code from Ariel Faigon.  */
 112   struct tm tm;
 113   tm.tm_year = 96;
 114   tm.tm_mon = 3;
 115   tm.tm_mday = 0;
 116   tm.tm_hour = 0;
 117   tm.tm_min = 0;
 118   tm.tm_sec = 0;
 119   tm.tm_isdst = -1;
 120   mktime (&tm);
 121   return tm.tm_mon == 2 && tm.tm_mday == 31;
 122 }
 123
 124 static int
 125 bigtime_test (int j)
 126 {
 127   struct tm tm;
 128   time_t now;
 129   tm.tm_year = tm.tm_mon = tm.tm_mday = tm.tm_hour = tm.tm_min = tm.tm_sec = j;
 130   now = mktime (&tm);
 131   if (now != (time_t) -1)
 132     {
 133       struct tm *lt = localtime (&now);
 134       if (! (lt
 135              && lt->tm_year == tm.tm_year
 136              && lt->tm_mon == tm.tm_mon
 137              && lt->tm_mday == tm.tm_mday
 138              && lt->tm_hour == tm.tm_hour
 139              && lt->tm_min == tm.tm_min
 140              && lt->tm_sec == tm.tm_sec
 141              && lt->tm_yday == tm.tm_yday
 142              && lt->tm_wday == tm.tm_wday
 143              && ((lt->tm_isdst < 0 ? -1 : 0 < lt->tm_isdst)
 144                   == (tm.tm_isdst < 0 ? -1 : 0 < tm.tm_isdst))))
 145         return 0;
 146     }
 147   return 1;
 148 }
 149
 150 static int
 151 year_2050_test ()
 152 {
 153   /* The correct answer for 2050-02-01 00:00:00 in Pacific time,
 154      ignoring leap seconds.  */
 155   unsigned long int answer = 2527315200UL;
 156
 157   struct tm tm;
 158   time_t t;
 159   tm.tm_year = 2050 - 1900;
 160   tm.tm_mon = 2 - 1;
 161   tm.tm_mday = 1;
 162   tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
 163   tm.tm_isdst = -1;
 164
 165   /* Use the portable POSIX.1 specification "TZ=PST8PDT,M4.1.0,M10.5.0"
 166      instead of "TZ=America/Vancouver" in order to detect the bug even
 167      on systems that don't support the Olson extension, or don't have the
 168      full zoneinfo tables installed.  */
 169   putenv ("TZ=PST8PDT,M4.1.0,M10.5.0");
 170
 171   t = mktime (&tm);
 172
 173   /* Check that the result is either a failure, or close enough
 174      to the correct answer that we can assume the discrepancy is
 175      due to leap seconds.  */
 176   return (t == (time_t) -1
 177           || (0 < t && answer - 120 <= t && t <= answer + 120));
 178 }
 179
 180 int
 181 main ()
 182 {
 183   int result = 0;
 184   time_t t, delta;
 185   int i, j;
 186   int time_t_signed_magnitude = (time_t) ~ (time_t) 0 < (time_t) -1;
 187
 188 #if HAVE_DECL_ALARM
 189   /* This test makes some buggy mktime implementations loop.
 190      Give up after 60 seconds; a mktime slower than that
 191      isn't worth using anyway.  */
 192   signal (SIGALRM, SIG_DFL);
 193   alarm (60);
 194 #endif
 195
 196   time_t_max = (! TIME_T_IS_SIGNED
 197                 ? (time_t) -1
 198                 : ((((time_t) 1 << (sizeof (time_t) * CHAR_BIT - 2)) - 1)
 199                    * 2 + 1));
 200   time_t_min = (! TIME_T_IS_SIGNED
 201                 ? (time_t) 0
 202                 : time_t_signed_magnitude
 203                 ? ~ (time_t) 0
 204                 : ~ time_t_max);
 205
 206   delta = time_t_max / 997; /* a suitable prime number */
 207   for (i = 0; i < N_STRINGS; i++)
 208     {
 209       if (tz_strings[i])
 210         putenv (tz_strings[i]);
 211
 212       for (t = 0; t <= time_t_max - delta && (result & 1) == 0; t += delta)
 213         if (! mktime_test (t))
 214           result |= 1;
 215       if ((result & 2) == 0
 216           && ! (mktime_test ((time_t) 1)
 217                 && mktime_test ((time_t) (60 * 60))
 218                 && mktime_test ((time_t) (60 * 60 * 24))))
 219         result |= 2;
 220
 221       for (j = 1; (result & 4) == 0; j <<= 1)
 222         {
 223           if (! bigtime_test (j))
 224             result |= 4;
 225           if (INT_MAX / 2 < j)
 226             break;
 227         }
 228       if ((result & 8) == 0 && ! bigtime_test (INT_MAX))
 229         result |= 8;
 230     }
 231   if (! irix_6_4_bug ())
 232     result |= 16;
 233   if (! spring_forward_gap ())
 234     result |= 32;
 235   if (! year_2050_test ())
 236     result |= 64;
 237   return result;
 238 }]])],
 239        [gl_cv_func_working_mktime=yes],
 240        [gl_cv_func_working_mktime=no],
 241        [gl_cv_func_working_mktime=no])
 242     ])
 243
 244   if test $gl_cv_func_working_mktime = no; then
 245     REPLACE_MKTIME=1
 246   else
 247     REPLACE_MKTIME=0
 248   fi
 249 ])
 250
 251 AC_DEFUN([gl_FUNC_MKTIME_INTERNAL], [
 252   AC_REQUIRE([gl_FUNC_MKTIME])
 253   if test $REPLACE_MKTIME = 0; then
 254     dnl BeOS has __mktime_internal in libc, but other platforms don't.
 255     AC_CHECK_FUNC([__mktime_internal],
 256       [AC_DEFINE([mktime_internal], [__mktime_internal],
 257          [Define to the real name of the mktime_internal function.])
 258       ],
 259       [dnl mktime works but it doesn't export __mktime_internal,
 260        dnl so we need to substitute our own mktime implementation.
 261        REPLACE_MKTIME=1
 262       ])
 263   fi
 264 ])
 265
 266 # Prerequisites of lib/mktime.c.
 267 AC_DEFUN([gl_PREREQ_MKTIME], [:])