1 /* Copyright (C) 1991, 92, 93, 95, 96, 97 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. */
33 long int offset; /* Seconds east of GMT. */
34 unsigned char isdst; /* Used to set tm_isdst. */
35 unsigned char idx; /* Index into `zone_names'. */
36 unsigned char isstd; /* Transition times are in standard time. */
37 unsigned char isgmt; /* Transition times are in GMT. */
42 time_t transition; /* Time the transition takes effect. */
43 long int change; /* Seconds of correction to apply. */
46 extern const char * __tzstring (const char *); /* Defined in tzset.c. */
48 static struct ttinfo *find_transition (time_t timer);
49 static void compute_tzname_max (size_t);
51 static size_t num_transitions;
52 static time_t *transitions = NULL;
53 static unsigned char *type_idxs = NULL;
54 static size_t num_types;
55 static struct ttinfo *types = NULL;
56 static char *zone_names = NULL;
57 static size_t num_leaps;
58 static struct leap *leaps = NULL;
62 /* Decode the four bytes at PTR as a signed integer in network byte order. */
64 decode (const void *ptr)
66 if ((BYTE_ORDER == BIG_ENDIAN) && sizeof (int) == 4)
67 return *(const int *) ptr;
70 const unsigned char *p = ptr;
71 int result = *p & (1 << (CHAR_BIT - 1)) ? ~0 : 0;
73 result = (result << 8) | *p++;
74 result = (result << 8) | *p++;
75 result = (result << 8) | *p++;
76 result = (result << 8) | *p++;
83 __tzfile_read (const char *file)
85 static const char default_tzdir[] = TZDIR;
86 size_t num_isstd, num_isgmt;
95 if (transitions != NULL)
96 free ((void *) transitions);
98 if (type_idxs != NULL)
99 free ((void *) type_idxs);
102 free ((void *) types);
104 if (zone_names != NULL)
105 free ((void *) zone_names);
108 free ((void *) leaps);
112 /* No user specification; use the site-wide default. */
114 else if (*file == '\0')
115 /* User specified the empty string; use UTC explicitly. */
119 /* We must not allow to read an arbitrary file in a setuid
120 program. So we fail for any file which is not in the
121 directory hierachy starting at TZDIR
122 and which is not the system wide default TZDEFAULT. */
123 if (__libc_enable_secure
125 && memcmp (file, TZDEFAULT, sizeof TZDEFAULT)
126 && memcmp (file, default_tzdir, sizeof (default_tzdir) - 1))
127 || strstr (file, "../") != NULL))
128 /* This test is certainly a bit too restrictive but it should
129 catch all critical cases. */
136 unsigned int len, tzdir_len;
139 tzdir = __secure_getenv ("TZDIR");
140 if (tzdir == NULL || *tzdir == '\0')
142 tzdir = default_tzdir;
143 tzdir_len = sizeof (default_tzdir) - 1;
146 tzdir_len = strlen (tzdir);
147 len = strlen (file) + 1;
148 new = (char *) __alloca (tzdir_len + 1 + len);
149 memcpy (new, tzdir, tzdir_len);
150 new[tzdir_len] = '/';
151 memcpy (&new[tzdir_len + 1], file, len);
155 f = fopen (file, "r");
159 if (fread ((void *) &tzhead, sizeof (tzhead), 1, f) != 1)
162 num_transitions = (size_t) decode (tzhead.tzh_timecnt);
163 num_types = (size_t) decode (tzhead.tzh_typecnt);
164 chars = (size_t) decode (tzhead.tzh_charcnt);
165 num_leaps = (size_t) decode (tzhead.tzh_leapcnt);
166 num_isstd = (size_t) decode (tzhead.tzh_ttisstdcnt);
167 num_isgmt = (size_t) decode (tzhead.tzh_ttisgmtcnt);
169 if (num_transitions > 0)
171 transitions = (time_t *) malloc (num_transitions * sizeof(time_t));
172 if (transitions == NULL)
174 type_idxs = (unsigned char *) malloc (num_transitions);
175 if (type_idxs == NULL)
180 types = (struct ttinfo *) malloc (num_types * sizeof (struct ttinfo));
186 zone_names = (char *) malloc (chars);
187 if (zone_names == NULL)
192 leaps = (struct leap *) malloc (num_leaps * sizeof (struct leap));
197 if (sizeof (time_t) < 4)
200 if (fread(transitions, 4, num_transitions, f) != num_transitions ||
201 fread(type_idxs, 1, num_transitions, f) != num_transitions)
204 /* Check for bogus indices in the data file, so we can hereafter
205 safely use type_idxs[T] as indices into `types' and never crash. */
206 for (i = 0; i < num_transitions; ++i)
207 if (type_idxs[i] >= num_types)
210 if (BYTE_ORDER != BIG_ENDIAN || sizeof (time_t) != 4)
212 /* Decode the transition times, stored as 4-byte integers in
213 network (big-endian) byte order. We work from the end of
214 the array so as not to clobber the next element to be
215 processed when sizeof (time_t) > 4. */
218 transitions[i] = decode ((char *) transitions + i*4);
221 for (i = 0; i < num_types; ++i)
224 if (fread (x, 1, 4, f) != 4 ||
225 fread (&types[i].isdst, 1, 1, f) != 1 ||
226 fread (&types[i].idx, 1, 1, f) != 1)
228 if (types[i].idx >= chars) /* Bogus index in data file. */
230 types[i].offset = (long int) decode (x);
233 if (fread (zone_names, 1, chars, f) != chars)
236 for (i = 0; i < num_leaps; ++i)
239 if (fread (x, 1, sizeof (x), f) != sizeof (x))
241 leaps[i].transition = (time_t) decode (x);
242 if (fread (x, 1, sizeof (x), f) != sizeof (x))
244 leaps[i].change = (long int) decode (x);
247 for (i = 0; i < num_isstd; ++i)
252 types[i].isstd = c != 0;
254 while (i < num_types)
255 types[i++].isstd = 0;
257 for (i = 0; i < num_isgmt; ++i)
262 types[i].isgmt = c != 0;
264 while (i < num_types)
265 types[i++].isgmt = 0;
269 info = find_transition (0);
270 for (i = 0; i < num_types && i < sizeof (__tzname) / sizeof (__tzname[0]);
272 __tzname[types[i].isdst] = __tzstring (&zone_names[types[i].idx]);
273 if (info->isdst < sizeof (__tzname) / sizeof (__tzname[0]))
274 __tzname[info->isdst] = __tzstring (&zone_names[info->idx]);
276 compute_tzname_max (chars);
285 /* The user specified a hand-made timezone, but not its DST rules.
286 We will use the names and offsets from the user, and the rules
287 from the TZDEFRULES file. */
290 __tzfile_default (const char *std, const char *dst,
291 long int stdoff, long int dstoff)
293 size_t stdlen, dstlen, i;
294 long int rule_offset, rule_stdoff, rule_dstoff;
297 __tzfile_read (TZDEFRULES);
307 /* Ignore the zone names read from the file. */
310 /* Use the names the user specified. */
311 stdlen = strlen (std) + 1;
312 dstlen = strlen (dst) + 1;
313 zone_names = malloc (stdlen + dstlen);
314 if (zone_names == NULL)
319 memcpy (zone_names, std, stdlen);
320 memcpy (&zone_names[stdlen], dst, dstlen);
322 /* Find the standard and daylight time offsets used by the rule file.
323 We choose the offsets in the types of each flavor that are
324 transitioned to earliest in time. */
325 rule_stdoff = rule_dstoff = 0;
326 for (i = 0; i < num_transitions; ++i)
328 if (!rule_stdoff && !types[type_idxs[i]].isdst)
329 rule_stdoff = types[type_idxs[i]].offset;
330 if (!rule_dstoff && types[type_idxs[i]].isdst)
331 rule_dstoff = types[type_idxs[i]].offset;
332 if (rule_stdoff && rule_dstoff)
336 /* Now correct the transition times for the user-specified standard and
337 daylight offsets from GMT. */
339 rule_offset = rule_offset;
340 for (i = 0; i < num_transitions; ++i)
342 struct ttinfo *trans_type = &types[type_idxs[i]];
344 /* We will use only types 0 (standard) and 1 (daylight).
345 Fix up this transition to point to whichever matches
346 the flavor of its original type. */
347 type_idxs[i] = trans_type->isdst;
349 if (trans_type->isgmt)
350 /* The transition time is in GMT. No correction to apply. */ ;
351 else if (isdst && !trans_type->isstd)
352 /* The type says this transition is in "local wall clock time", and
353 wall clock time as of the previous transition was DST. Correct
354 for the difference between the rule's DST offset and the user's
356 transitions[i] += dstoff - rule_dstoff;
358 /* This transition is in "local wall clock time", and wall clock
359 time as of this iteration is non-DST. Correct for the
360 difference between the rule's standard offset and the user's
362 transitions[i] += stdoff - rule_stdoff;
364 /* The DST state of "local wall clock time" for the next iteration is
365 as specified by this transition. */
366 isdst = trans_type->isdst;
369 /* Reset types 0 and 1 to describe the user's settings. */
371 types[0].offset = stdoff;
373 types[1].idx = stdlen;
374 types[1].offset = dstoff;
377 /* Reset the zone names to point to the user's names. */
378 __tzname[0] = (char *) std;
379 __tzname[1] = (char *) dst;
381 compute_tzname_max (stdlen + dstlen);
384 static struct ttinfo *
385 find_transition (time_t timer)
389 if (num_transitions == 0 || timer < transitions[0])
391 /* TIMER is before any transition (or there are no transitions).
392 Choose the first non-DST type
393 (or the first if they're all DST types). */
395 while (i < num_types && types[i].isdst)
402 /* Find the first transition after TIMER, and
403 then pick the type of the transition before it. */
404 for (i = 1; i < num_transitions; ++i)
405 if (timer < transitions[i])
407 i = type_idxs[i - 1];
414 __tzfile_compute (time_t timer, long int *leap_correct, int *leap_hit)
419 info = find_transition (timer);
420 __daylight = info->isdst;
421 __timezone = info->offset;
422 for (i = 0; i < num_types && i < sizeof (__tzname) / sizeof (__tzname[0]);
424 __tzname[types[i].isdst] = &zone_names[types[i].idx];
425 if (info->isdst < sizeof (__tzname) / sizeof (__tzname[0]))
426 __tzname[info->isdst] = &zone_names[info->idx];
431 /* Find the last leap second correction transition time before TIMER. */
436 while (timer < leaps[i].transition);
438 /* Apply its correction. */
439 *leap_correct = leaps[i].change;
441 if (timer == leaps[i].transition && /* Exactly at the transition time. */
442 ((i == 0 && leaps[i].change > 0) ||
443 leaps[i].change > leaps[i - 1].change))
447 leaps[i].transition == leaps[i - 1].transition + 1 &&
448 leaps[i].change == leaps[i - 1].change + 1)
459 compute_tzname_max (size_t chars)
461 extern size_t __tzname_cur_max; /* Defined in tzset.c. */
468 const char *start = p;
471 if ((size_t) (p - start) > __tzname_cur_max)
472 __tzname_cur_max = p - start;
473 } while (++p < &zone_names[chars]);