summaryrefslogtreecommitdiffstats
path: root/m4/mktime.m4
blob: 4b3e399be9f4e1e2c982cb783c891591cc46b11d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
# serial 30
dnl Copyright (C) 2002-2003, 2005-2007, 2009-2018 Free Software Foundation,
dnl Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

dnl From Jim Meyering.

AC_DEFUN([gl_TIME_T_IS_SIGNED],
[
  AC_CACHE_CHECK([whether time_t is signed],
    [gl_cv_time_t_is_signed],
    [AC_COMPILE_IFELSE(
       [AC_LANG_PROGRAM([[#include <time.h>
                          char time_t_signed[(time_t) -1 < 0 ? 1 : -1];]])],
       [gl_cv_time_t_is_signed=yes],
       [gl_cv_time_t_is_signed=no])])
  if test $gl_cv_time_t_is_signed = yes; then
    AC_DEFINE([TIME_T_IS_SIGNED], [1], [Define to 1 if time_t is signed.])
  fi
])

dnl Test whether mktime works. Set gl_cv_func_working_mktime.
AC_DEFUN([gl_FUNC_MKTIME_WORKS],
[
  AC_REQUIRE([gl_TIME_T_IS_SIGNED])
  AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles

  dnl We don't use AC_FUNC_MKTIME any more, because it is no longer maintained
  dnl in Autoconf and because it invokes AC_LIBOBJ.
  AC_CHECK_HEADERS_ONCE([unistd.h])
  AC_CHECK_DECLS_ONCE([alarm])
  AC_CHECK_FUNCS_ONCE([tzset])
  AC_REQUIRE([gl_MULTIARCH])
  if test $APPLE_UNIVERSAL_BUILD = 1; then
    # A universal build on Apple Mac OS X platforms.
    # The test result would be 'yes' in 32-bit mode and 'no' in 64-bit mode.
    # But we need a configuration result that is valid in both modes.
    gl_cv_func_working_mktime=no
  fi
  AC_CACHE_CHECK([for working mktime], [gl_cv_func_working_mktime],
    [AC_RUN_IFELSE(
       [AC_LANG_SOURCE(
[[/* Test program from Paul Eggert and Tony Leneis.  */
#include <limits.h>
#include <stdlib.h>
#include <time.h>

#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif

#if HAVE_DECL_ALARM
# include <signal.h>
#endif

#ifndef TIME_T_IS_SIGNED
# define TIME_T_IS_SIGNED 0
#endif

/* Work around redefinition to rpl_putenv by other config tests.  */
#undef putenv

static time_t time_t_max;
static time_t time_t_min;

/* Values we'll use to set the TZ environment variable.  */
static char *tz_strings[] = {
  (char *) 0, "TZ=GMT0", "TZ=JST-9",
  "TZ=EST+3EDT+2,M10.1.0/00:00:00,M2.3.0/00:00:00"
};
#define N_STRINGS (sizeof (tz_strings) / sizeof (tz_strings[0]))

/* Return 0 if mktime fails to convert a date in the spring-forward gap.
   Based on a problem report from Andreas Jaeger.  */
static int
spring_forward_gap ()
{
  /* glibc (up to about 1998-10-07) failed this test. */
  struct tm tm;

  /* Use the portable POSIX.1 specification "TZ=PST8PDT,M4.1.0,M10.5.0"
     instead of "TZ=America/Vancouver" in order to detect the bug even
     on systems that don't support the Olson extension, or don't have the
     full zoneinfo tables installed.  */
  putenv ("TZ=PST8PDT,M4.1.0,M10.5.0");

  tm.tm_year = 98;
  tm.tm_mon = 3;
  tm.tm_mday = 5;
  tm.tm_hour = 2;
  tm.tm_min = 0;
  tm.tm_sec = 0;
  tm.tm_isdst = -1;
  return mktime (&tm) != (time_t) -1;
}

static int
mktime_test1 (time_t now)
{
  struct tm *lt;
  return ! (lt = localtime (&now)) || mktime (lt) == now;
}

static int
mktime_test (time_t now)
{
  return (mktime_test1 (now)
          && mktime_test1 ((time_t) (time_t_max - now))
          && mktime_test1 ((time_t) (time_t_min + now)));
}

static int
irix_6_4_bug ()
{
  /* Based on code from Ariel Faigon.  */
  struct tm tm;
  tm.tm_year = 96;
  tm.tm_mon = 3;
  tm.tm_mday = 0;
  tm.tm_hour = 0;
  tm.tm_min = 0;
  tm.tm_sec = 0;
  tm.tm_isdst = -1;
  mktime (&tm);
  return tm.tm_mon == 2 && tm.tm_mday == 31;
}

static int
bigtime_test (int j)
{
  struct tm tm;
  time_t now;
  tm.tm_year = tm.tm_mon = tm.tm_mday = tm.tm_hour = tm.tm_min = tm.tm_sec = j;
  now = mktime (&tm);
  if (now != (time_t) -1)
    {
      struct tm *lt = localtime (&now);
      if (! (lt
             && lt->tm_year == tm.tm_year
             && lt->tm_mon == tm.tm_mon
             && lt->tm_mday == tm.tm_mday
             && lt->tm_hour == tm.tm_hour
             && lt->tm_min == tm.tm_min
             && lt->tm_sec == tm.tm_sec
             && lt->tm_yday == tm.tm_yday
             && lt->tm_wday == tm.tm_wday
             && ((lt->tm_isdst < 0 ? -1 : 0 < lt->tm_isdst)
                  == (tm.tm_isdst < 0 ? -1 : 0 < tm.tm_isdst))))
        return 0;
    }
  return 1;
}

static int
year_2050_test ()
{
  /* The correct answer for 2050-02-01 00:00:00 in Pacific time,
     ignoring leap seconds.  */
  unsigned long int answer = 2527315200UL;

  struct tm tm;
  time_t t;
  tm.tm_year = 2050 - 1900;
  tm.tm_mon = 2 - 1;
  tm.tm_mday = 1;
  tm.tm_hour = tm.tm_min = tm.tm_sec = 0;
  tm.tm_isdst = -1;

  /* Use the portable POSIX.1 specification "TZ=PST8PDT,M4.1.0,M10.5.0"
     instead of "TZ=America/Vancouver" in order to detect the bug even
     on systems that don't support the Olson extension, or don't have the
     full zoneinfo tables installed.  */
  putenv ("TZ=PST8PDT,M4.1.0,M10.5.0");

  t = mktime (&tm);

  /* Check that the result is either a failure, or close enough
     to the correct answer that we can assume the discrepancy is
     due to leap seconds.  */
  return (t == (time_t) -1
          || (0 < t && answer - 120 <= t && t <= answer + 120));
}

int
main ()
{
  int result = 0;
  time_t t, delta;
  int i, j;
  int time_t_signed_magnitude = (time_t) ~ (time_t) 0 < (time_t) -1;

#if HAVE_DECL_ALARM
  /* This test makes some buggy mktime implementations loop.
     Give up after 60 seconds; a mktime slower than that
     isn't worth using anyway.  */
  signal (SIGALRM, SIG_DFL);
  alarm (60);
#endif

  time_t_max = (! TIME_T_IS_SIGNED
                ? (time_t) -1
                : ((((time_t) 1 << (sizeof (time_t) * CHAR_BIT - 2)) - 1)
                   * 2 + 1));
  time_t_min = (! TIME_T_IS_SIGNED
                ? (time_t) 0
                : time_t_signed_magnitude
                ? ~ (time_t) 0
                : ~ time_t_max);

  delta = time_t_max / 997; /* a suitable prime number */
  for (i = 0; i < N_STRINGS; i++)
    {
      if (tz_strings[i])
        putenv (tz_strings[i]);

      for (t = 0; t <= time_t_max - delta && (result & 1) == 0; t += delta)
        if (! mktime_test (t))
          result |= 1;
      if ((result & 2) == 0
          && ! (mktime_test ((time_t) 1)
                && mktime_test ((time_t) (60 * 60))
                && mktime_test ((time_t) (60 * 60 * 24))))
        result |= 2;

      for (j = 1; (result & 4) == 0; j <<= 1)
        {
          if (! bigtime_test (j))
            result |= 4;
          if (INT_MAX / 2 < j)
            break;
        }
      if ((result & 8) == 0 && ! bigtime_test (INT_MAX))
        result |= 8;
    }
  if (! irix_6_4_bug ())
    result |= 16;
  if (! spring_forward_gap ())
    result |= 32;
  if (! year_2050_test ())
    result |= 64;
  return result;
}]])],
       [gl_cv_func_working_mktime=yes],
       [gl_cv_func_working_mktime=no],
       [case "$host_os" in
                  # Guess no on native Windows.
          mingw*) gl_cv_func_working_mktime="guessing no" ;;
          *)      gl_cv_func_working_mktime="guessing no" ;;
        esac
       ])
    ])
])

dnl Main macro of module 'mktime'.
AC_DEFUN([gl_FUNC_MKTIME],
[
  AC_REQUIRE([gl_HEADER_TIME_H_DEFAULTS])
  AC_REQUIRE([AC_CANONICAL_HOST])
  AC_REQUIRE([gl_FUNC_MKTIME_WORKS])

  REPLACE_MKTIME=0
  if test "$gl_cv_func_working_mktime" != yes; then
    REPLACE_MKTIME=1
    AC_DEFINE([NEED_MKTIME_WORKING], [1],
      [Define if the compilation of mktime.c should define 'mktime'
       with the algorithmic workarounds.])
  fi
  case "$host_os" in
    mingw*)
      REPLACE_MKTIME=1
      AC_DEFINE([NEED_MKTIME_WINDOWS], [1],
        [Define if the compilation of mktime.c should define 'mktime'
         with the native Windows TZ workaround.])
      ;;
  esac
])

dnl Main macro of module 'mktime-internal'.
AC_DEFUN([gl_FUNC_MKTIME_INTERNAL], [
  AC_REQUIRE([gl_FUNC_MKTIME_WORKS])

  WANT_MKTIME_INTERNAL=0
  dnl BeOS has __mktime_internal in libc, but other platforms don't.
  AC_CHECK_FUNC([__mktime_internal],
    [AC_DEFINE([mktime_internal], [__mktime_internal],
       [Define to the real name of the mktime_internal function.])
    ],
    [dnl mktime works but it doesn't export __mktime_internal,
     dnl so we need to substitute our own mktime implementation.
     WANT_MKTIME_INTERNAL=1
     AC_DEFINE([NEED_MKTIME_INTERNAL], [1],
       [Define if the compilation of mktime.c should define 'mktime_internal'.])
    ])
])

# Prerequisites of lib/mktime.c.
AC_DEFUN([gl_PREREQ_MKTIME], [:])