1 /* Copyright (C) 1991, 92, 93, 95, 96 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Library General Public License as
6 published by the Free Software Foundation; either version 2 of the
7 License, or (at your option) any later version.
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Library General Public License for more details.
14 You should have received a copy of the GNU Library General Public
15 License along with the GNU C Library; see the file COPYING.LIB. If not,
16 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 Boston, MA 02111-1307, USA. */
32 long int offset; /* Seconds east of GMT. */
33 unsigned char isdst; /* Used to set tm_isdst. */
34 unsigned char idx; /* Index into `zone_names'. */
35 unsigned char isstd; /* Transition times are in standard time. */
36 unsigned char isgmt; /* Transition times are in GMT. */
41 time_t transition; /* Time the transition takes effect. */
42 long int change; /* Seconds of correction to apply. */
45 static struct ttinfo *find_transition (time_t timer);
46 static void compute_tzname_max (size_t);
48 static size_t num_transitions;
49 static time_t *transitions = NULL;
50 static unsigned char *type_idxs = NULL;
51 static size_t num_types;
52 static struct ttinfo *types = NULL;
53 static char *zone_names = NULL;
54 static size_t num_leaps;
55 static struct leap *leaps = NULL;
59 /* Decode the four bytes at PTR as a signed integer in network byte order. */
61 decode (const void *ptr)
63 if ((BYTE_ORDER == BIG_ENDIAN) && sizeof (int) == 4)
64 return *(const int *) ptr;
67 const unsigned char *p = ptr;
68 int result = *p & (1 << (CHAR_BIT - 1)) ? ~0 : 0;
70 result = (result << 8) | *p++;
71 result = (result << 8) | *p++;
72 result = (result << 8) | *p++;
73 result = (result << 8) | *p++;
80 __tzfile_read (const char *file)
82 size_t num_isstd, num_isgmt;
91 if (transitions != NULL)
92 free ((void *) transitions);
94 if (type_idxs != NULL)
95 free ((void *) type_idxs);
98 free ((void *) types);
100 if (zone_names != NULL)
101 free ((void *) zone_names);
104 free ((void *) leaps);
108 /* No user specification; use the site-wide default. */
110 else if (*file == '\0')
111 /* User specified the empty string; use UTC explicitly. */
116 static const char tzdir[] = TZDIR;
117 register const unsigned int len = strlen (file) + 1;
118 char *new = (char *) __alloca (sizeof (tzdir) + len);
119 memcpy (new, tzdir, sizeof(tzdir) - 1);
120 new[sizeof (tzdir) - 1] = '/';
121 memcpy (&new[sizeof (tzdir)], file, len);
125 f = fopen(file, "r");
129 if (fread ((void *) &tzhead, sizeof (tzhead), 1, f) != 1)
132 num_transitions = (size_t) decode (tzhead.tzh_timecnt);
133 num_types = (size_t) decode (tzhead.tzh_typecnt);
134 chars = (size_t) decode (tzhead.tzh_charcnt);
135 num_leaps = (size_t) decode (tzhead.tzh_leapcnt);
136 num_isstd = (size_t) decode (tzhead.tzh_ttisstdcnt);
137 num_isgmt = (size_t) decode (tzhead.tzh_ttisgmtcnt);
139 if (num_transitions > 0)
141 transitions = (time_t *) malloc (num_transitions * sizeof(time_t));
142 if (transitions == NULL)
144 type_idxs = (unsigned char *) malloc (num_transitions);
145 if (type_idxs == NULL)
150 types = (struct ttinfo *) malloc (num_types * sizeof (struct ttinfo));
156 zone_names = (char *) malloc (chars);
157 if (zone_names == NULL)
162 leaps = (struct leap *) malloc (num_leaps * sizeof (struct leap));
167 if (sizeof (time_t) < 4)
170 if (fread(transitions, 4, num_transitions, f) != num_transitions ||
171 fread(type_idxs, 1, num_transitions, f) != num_transitions)
174 if (BYTE_ORDER != BIG_ENDIAN || sizeof (time_t) != 4)
176 /* Decode the transition times, stored as 4-byte integers in
177 network (big-endian) byte order. We work from the end of
178 the array so as not to clobber the next element to be
179 processed when sizeof (time_t) > 4. */
182 transitions[i] = decode ((char *) transitions + i*4);
185 for (i = 0; i < num_types; ++i)
188 if (fread (x, 1, 4, f) != 4 ||
189 fread (&types[i].isdst, 1, 1, f) != 1 ||
190 fread (&types[i].idx, 1, 1, f) != 1)
192 types[i].offset = (long int) decode (x);
195 if (fread (zone_names, 1, chars, f) != chars)
198 for (i = 0; i < num_leaps; ++i)
201 if (fread (x, 1, sizeof (x), f) != sizeof (x))
203 leaps[i].transition = (time_t) decode (x);
204 if (fread (x, 1, sizeof (x), f) != sizeof (x))
206 leaps[i].change = (long int) decode (x);
209 for (i = 0; i < num_isstd; ++i)
214 types[i].isstd = c != 0;
216 while (i < num_types)
217 types[i++].isstd = 0;
219 for (i = 0; i < num_isgmt; ++i)
224 types[i].isgmt = c != 0;
226 while (i < num_types)
227 types[i++].isgmt = 0;
231 info = find_transition (0);
232 for (i = 0; i < num_types && i < sizeof (__tzname) / sizeof (__tzname[0]);
234 __tzname[types[i].isdst] = &zone_names[types[i].idx];
235 if (info->isdst < sizeof (__tzname) / sizeof (__tzname[0]))
236 __tzname[info->isdst] = &zone_names[info->idx];
238 compute_tzname_max (chars);
247 /* The user specified a hand-made timezone, but not its DST rules.
248 We will use the names and offsets from the user, and the rules
249 from the TZDEFRULES file. */
252 __tzfile_default (char *std, char *dst, long int stdoff, long int dstoff)
254 size_t stdlen, dstlen, i;
255 long int rule_offset, rule_stdoff, rule_dstoff;
258 __tzfile_read (TZDEFRULES);
268 /* Ignore the zone names read from the file. */
271 /* Use the names the user specified. */
272 stdlen = strlen (std) + 1;
273 dstlen = strlen (dst) + 1;
274 zone_names = malloc (stdlen + dstlen);
275 if (zone_names == NULL)
280 memcpy (zone_names, std, stdlen);
281 memcpy (&zone_names[stdlen], dst, dstlen);
283 /* Find the standard and daylight time offsets used by the rule file.
284 We choose the offsets in the types of each flavor that are
285 transitioned to earliest in time. */
286 rule_stdoff = rule_dstoff = 0;
287 for (i = 0; i < num_transitions; ++i)
289 if (!rule_stdoff && !types[type_idxs[i]].isdst)
290 rule_stdoff = types[type_idxs[i]].offset;
291 if (!rule_dstoff && types[type_idxs[i]].isdst)
292 rule_dstoff = types[type_idxs[i]].offset;
293 if (rule_stdoff && rule_dstoff)
297 /* Now correct the transition times for the user-specified standard and
298 daylight offsets from GMT. */
300 rule_offset = rule_offset;
301 for (i = 0; i < num_transitions; ++i)
303 struct ttinfo *trans_type = &types[type_idxs[i]];
305 /* We will use only types 0 (standard) and 1 (daylight).
306 Fix up this transition to point to whichever matches
307 the flavor of its original type. */
308 type_idxs[i] = trans_type->isdst;
310 if (trans_type->isgmt)
311 /* The transition time is in GMT. No correction to apply. */ ;
312 else if (isdst && !trans_type->isstd)
313 /* The type says this transition is in "local wall clock time", and
314 wall clock time as of the previous transition was DST. Correct
315 for the difference between the rule's DST offset and the user's
317 transitions[i] += dstoff - rule_dstoff;
319 /* This transition is in "local wall clock time", and wall clock
320 time as of this iteration is non-DST. Correct for the
321 difference between the rule's standard offset and the user's
323 transitions[i] += stdoff - rule_stdoff;
325 /* The DST state of "local wall clock time" for the next iteration is
326 as specified by this transition. */
327 isdst = trans_type->isdst;
330 /* Reset types 0 and 1 to describe the user's settings. */
332 types[0].offset = stdoff;
334 types[1].idx = stdlen;
335 types[1].offset = dstoff;
338 compute_tzname_max (stdlen + dstlen);
341 static struct ttinfo *
342 find_transition (time_t timer)
346 if (num_transitions == 0 || timer < transitions[0])
348 /* TIMER is before any transition (or there are no transitions).
349 Choose the first non-DST type
350 (or the first if they're all DST types). */
352 while (i < num_types && types[i].isdst)
359 /* Find the first transition after TIMER, and
360 then pick the type of the transition before it. */
361 for (i = 1; i < num_transitions; ++i)
362 if (timer < transitions[i])
364 i = type_idxs[i - 1];
371 __tzfile_compute (time_t timer, long int *leap_correct, int *leap_hit)
376 info = find_transition (timer);
377 __daylight = info->isdst;
378 __timezone = info->offset;
379 for (i = 0; i < num_types && i < sizeof (__tzname) / sizeof (__tzname[0]);
381 __tzname[types[i].isdst] = &zone_names[types[i].idx];
382 if (info->isdst < sizeof (__tzname) / sizeof (__tzname[0]))
383 __tzname[info->isdst] = &zone_names[info->idx];
388 /* Find the last leap second correction transition time before TIMER. */
393 while (timer < leaps[i].transition);
395 /* Apply its correction. */
396 *leap_correct = leaps[i].change;
398 if (timer == leaps[i].transition && /* Exactly at the transition time. */
399 ((i == 0 && leaps[i].change > 0) ||
400 leaps[i].change > leaps[i - 1].change))
404 leaps[i].transition == leaps[i - 1].transition + 1 &&
405 leaps[i].change == leaps[i - 1].change + 1)
416 compute_tzname_max (size_t chars)
418 extern size_t __tzname_cur_max; /* Defined in __tzset.c. */
425 const char *start = p;
428 if (p - start > __tzname_cur_max)
429 __tzname_cur_max = p - start;
430 } while (++p < &zone_names[chars]);