1 /* Copyright (C) 1991, 92, 93, 95, 96, 97, 98 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. */
27 #include <timezone/tzfile.h>
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 char * __tzstring (const char *); /* Defined in tzset.c. */
48 static struct ttinfo *find_transition (time_t timer) internal_function;
49 static void compute_tzname_max (size_t) internal_function;
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 long int rule_stdoff;
58 static long int rule_dstoff;
59 static size_t num_leaps;
60 static struct leap *leaps = NULL;
64 /* Decode the four bytes at PTR as a signed integer in network byte order. */
66 decode (const void *ptr)
68 if ((BYTE_ORDER == BIG_ENDIAN) && sizeof (int) == 4)
69 return *(const int *) ptr;
72 const unsigned char *p = ptr;
73 int result = *p & (1 << (CHAR_BIT - 1)) ? ~0 : 0;
75 result = (result << 8) | *p++;
76 result = (result << 8) | *p++;
77 result = (result << 8) | *p++;
78 result = (result << 8) | *p++;
85 __tzfile_read (const char *file)
87 static const char default_tzdir[] = TZDIR;
88 size_t num_isstd, num_isgmt;
96 if (transitions != NULL)
97 free ((void *) transitions);
99 if (type_idxs != NULL)
100 free ((void *) type_idxs);
103 free ((void *) types);
105 if (zone_names != NULL)
106 free ((void *) zone_names);
109 free ((void *) leaps);
113 /* No user specification; use the site-wide default. */
115 else if (*file == '\0')
116 /* User specified the empty string; use UTC with no leap seconds. */
120 /* We must not allow to read an arbitrary file in a setuid
121 program. So we fail for any file which is not in the
122 directory hierachy starting at TZDIR
123 and which is not the system wide default TZDEFAULT. */
124 if (__libc_enable_secure
126 && memcmp (file, TZDEFAULT, sizeof TZDEFAULT)
127 && memcmp (file, default_tzdir, sizeof (default_tzdir) - 1))
128 || strstr (file, "../") != NULL))
129 /* This test is certainly a bit too restrictive but it should
130 catch all critical cases. */
137 unsigned int len, tzdir_len;
140 tzdir = __secure_getenv ("TZDIR");
141 if (tzdir == NULL || *tzdir == '\0')
143 tzdir = default_tzdir;
144 tzdir_len = sizeof (default_tzdir) - 1;
147 tzdir_len = strlen (tzdir);
148 len = strlen (file) + 1;
149 new = (char *) __alloca (tzdir_len + 1 + len);
150 tmp = __mempcpy (new, tzdir, tzdir_len);
152 __mempcpy (tmp, file, len);
156 f = fopen (file, "r");
160 if (fread ((void *) &tzhead, sizeof (tzhead), 1, f) != 1)
163 num_transitions = (size_t) decode (tzhead.tzh_timecnt);
164 num_types = (size_t) decode (tzhead.tzh_typecnt);
165 chars = (size_t) decode (tzhead.tzh_charcnt);
166 num_leaps = (size_t) decode (tzhead.tzh_leapcnt);
167 num_isstd = (size_t) decode (tzhead.tzh_ttisstdcnt);
168 num_isgmt = (size_t) decode (tzhead.tzh_ttisgmtcnt);
170 if (num_transitions > 0)
172 transitions = (time_t *) malloc (num_transitions * sizeof(time_t));
173 if (transitions == NULL)
175 type_idxs = (unsigned char *) malloc (num_transitions);
176 if (type_idxs == NULL)
181 types = (struct ttinfo *) malloc (num_types * sizeof (struct ttinfo));
187 zone_names = (char *) malloc (chars);
188 if (zone_names == NULL)
193 leaps = (struct leap *) malloc (num_leaps * sizeof (struct leap));
198 if (sizeof (time_t) < 4)
201 if (fread(transitions, 4, num_transitions, f) != num_transitions ||
202 fread(type_idxs, 1, num_transitions, f) != num_transitions)
205 /* Check for bogus indices in the data file, so we can hereafter
206 safely use type_idxs[T] as indices into `types' and never crash. */
207 for (i = 0; i < num_transitions; ++i)
208 if (type_idxs[i] >= num_types)
211 if (BYTE_ORDER != BIG_ENDIAN || sizeof (time_t) != 4)
213 /* Decode the transition times, stored as 4-byte integers in
214 network (big-endian) byte order. We work from the end of
215 the array so as not to clobber the next element to be
216 processed when sizeof (time_t) > 4. */
219 transitions[i] = decode ((char *) transitions + i*4);
222 for (i = 0; i < num_types; ++i)
225 if (fread (x, 1, 4, f) != 4 ||
226 fread (&types[i].isdst, 1, 1, f) != 1 ||
227 fread (&types[i].idx, 1, 1, f) != 1)
229 if (types[i].idx >= chars) /* Bogus index in data file. */
231 types[i].offset = (long int) decode (x);
234 if (fread (zone_names, 1, chars, f) != chars)
237 for (i = 0; i < num_leaps; ++i)
240 if (fread (x, 1, sizeof (x), f) != sizeof (x))
242 leaps[i].transition = (time_t) decode (x);
243 if (fread (x, 1, sizeof (x), f) != sizeof (x))
245 leaps[i].change = (long int) decode (x);
248 for (i = 0; i < num_isstd; ++i)
253 types[i].isstd = c != 0;
255 while (i < num_types)
256 types[i++].isstd = 0;
258 for (i = 0; i < num_isgmt; ++i)
263 types[i].isgmt = c != 0;
265 while (i < num_types)
266 types[i++].isgmt = 0;
270 /* Find the standard and daylight time offsets used by the rule file.
271 We choose the offsets in the types of each flavor that are
272 transitioned to earliest in time. */
274 for (i = 0; i < num_types && i < sizeof (__tzname) / sizeof (__tzname[0]);
276 __tzname[types[i].isdst] = __tzstring (&zone_names[types[i].idx]);
277 if (__tzname[1] == NULL)
278 __tzname[1] = __tzname[0];
280 compute_tzname_max (chars);
282 rule_stdoff = rule_dstoff = 0;
283 for (i = 0; i < num_transitions; ++i)
285 if (!rule_stdoff && !types[type_idxs[i]].isdst)
286 rule_stdoff = types[type_idxs[i]].offset;
287 if (!rule_dstoff && types[type_idxs[i]].isdst)
288 rule_dstoff = types[type_idxs[i]].offset;
289 if (rule_stdoff && rule_dstoff)
293 __daylight = rule_stdoff != rule_dstoff;
294 __timezone = -rule_stdoff;
303 /* The user specified a hand-made timezone, but not its DST rules.
304 We will use the names and offsets from the user, and the rules
305 from the TZDEFRULES file. */
308 __tzfile_default (const char *std, const char *dst,
309 long int stdoff, long int dstoff)
311 size_t stdlen, dstlen, i;
314 __tzfile_read (TZDEFRULES);
324 /* Ignore the zone names read from the file. */
327 /* Use the names the user specified. */
328 stdlen = strlen (std) + 1;
329 dstlen = strlen (dst) + 1;
330 zone_names = malloc (stdlen + dstlen);
331 if (zone_names == NULL)
336 __mempcpy (__mempcpy (zone_names, std, stdlen), dst, dstlen);
338 /* Now correct the transition times for the user-specified standard and
339 daylight offsets from GMT. */
341 for (i = 0; i < num_transitions; ++i)
343 struct ttinfo *trans_type = &types[type_idxs[i]];
345 /* We will use only types 0 (standard) and 1 (daylight).
346 Fix up this transition to point to whichever matches
347 the flavor of its original type. */
348 type_idxs[i] = trans_type->isdst;
350 if (trans_type->isgmt)
351 /* The transition time is in GMT. No correction to apply. */ ;
352 else if (isdst && !trans_type->isstd)
353 /* The type says this transition is in "local wall clock time", and
354 wall clock time as of the previous transition was DST. Correct
355 for the difference between the rule's DST offset and the user's
357 transitions[i] += dstoff - rule_dstoff;
359 /* This transition is in "local wall clock time", and wall clock
360 time as of this iteration is non-DST. Correct for the
361 difference between the rule's standard offset and the user's
363 transitions[i] += stdoff - rule_stdoff;
365 /* The DST state of "local wall clock time" for the next iteration is
366 as specified by this transition. */
367 isdst = trans_type->isdst;
370 /* Reset types 0 and 1 to describe the user's settings. */
372 types[0].offset = stdoff;
374 types[1].idx = stdlen;
375 types[1].offset = dstoff;
378 /* Reset the zone names to point to the user's names. */
379 __tzname[0] = (char *) std;
380 __tzname[1] = (char *) dst;
382 compute_tzname_max (stdlen + dstlen);
385 static struct ttinfo *
387 find_transition (time_t timer)
391 if (num_transitions == 0 || timer < transitions[0])
393 /* TIMER is before any transition (or there are no transitions).
394 Choose the first non-DST type
395 (or the first if they're all DST types). */
397 while (i < num_types && types[i].isdst)
404 /* Find the first transition after TIMER, and
405 then pick the type of the transition before it. */
406 for (i = 1; i < num_transitions; ++i)
407 if (timer < transitions[i])
409 i = type_idxs[i - 1];
416 __tzfile_compute (time_t timer, int use_localtime,
417 long int *leap_correct, int *leap_hit,
424 struct ttinfo *info = find_transition (timer);
425 __daylight = rule_stdoff != rule_dstoff;
426 __timezone = -rule_stdoff;
429 i < num_types && i < sizeof (__tzname) / sizeof (__tzname[0]);
431 __tzname[types[i].isdst] = &zone_names[types[i].idx];
432 if (__tzname[1] == NULL)
433 /* There is no daylight saving time. */
434 __tzname[1] = __tzname[0];
435 tp->tm_isdst = info->isdst;
436 tp->tm_zone = &zone_names[info->idx];
437 tp->tm_gmtoff = info->offset;
443 /* Find the last leap second correction transition time before TIMER. */
448 while (timer < leaps[i].transition);
450 /* Apply its correction. */
451 *leap_correct = leaps[i].change;
453 if (timer == leaps[i].transition && /* Exactly at the transition time. */
454 ((i == 0 && leaps[i].change > 0) ||
455 leaps[i].change > leaps[i - 1].change))
459 leaps[i].transition == leaps[i - 1].transition + 1 &&
460 leaps[i].change == leaps[i - 1].change + 1)
472 compute_tzname_max (size_t chars)
474 extern size_t __tzname_cur_max; /* Defined in tzset.c. */
481 const char *start = p;
484 if ((size_t) (p - start) > __tzname_cur_max)
485 __tzname_cur_max = p - start;
486 } while (++p < &zone_names[chars]);