1 #include "time_impl.h"
2 #include <stdint.h>
3 #include <limits.h>
4 #include <stdlib.h>
5 #include <string.h>
6 #include <sys/mman.h>
7 #include "libc.h"
8 #include "lock.h"
9
10 long __timezone = 0;
11 int __daylight = 0;
12 char *__tzname[2] = { 0, 0 };
13
14 weak_alias(__timezone, timezone);
15 weak_alias(__daylight, daylight);
16 weak_alias(__tzname, tzname);
17
18 static char std_name[TZNAME_MAX+1];
19 static char dst_name[TZNAME_MAX+1];
20 const char __utc[] = "UTC";
21
22 static int dst_off;
23 static int r0[5], r1[5];
24
25 static const unsigned char *zi, *trans, *index, *types, *abbrevs, *abbrevs_end;
26 static size_t map_size;
27
28 static char old_tz_buf[32];
29 static char *old_tz = old_tz_buf;
30 static size_t old_tz_size = sizeof old_tz_buf;
31
32 static volatile int lock[1];
33
getint(const char ** p)34 static int getint(const char **p)
35 {
36 unsigned x;
37 for (x=0; **p-'0'<10U; (*p)++) x = **p-'0' + 10*x;
38 return x;
39 }
40
getoff(const char ** p)41 static int getoff(const char **p)
42 {
43 int neg = 0;
44 if (**p == '-') {
45 ++*p;
46 neg = 1;
47 } else if (**p == '+') {
48 ++*p;
49 }
50 int off = 3600*getint(p);
51 if (**p == ':') {
52 ++*p;
53 off += 60*getint(p);
54 if (**p == ':') {
55 ++*p;
56 off += getint(p);
57 }
58 }
59 return neg ? -off : off;
60 }
61
getrule(const char ** p,int rule[5])62 static void getrule(const char **p, int rule[5])
63 {
64 int r = rule[0] = **p;
65
66 if (r!='M') {
67 if (r=='J') ++*p;
68 else rule[0] = 0;
69 rule[1] = getint(p);
70 } else {
71 ++*p; rule[1] = getint(p);
72 ++*p; rule[2] = getint(p);
73 ++*p; rule[3] = getint(p);
74 }
75
76 if (**p=='/') {
77 ++*p;
78 rule[4] = getoff(p);
79 } else {
80 rule[4] = 7200;
81 }
82 }
83
getname(char * d,const char ** p)84 static void getname(char *d, const char **p)
85 {
86 int i;
87 if (**p == '<') {
88 ++*p;
89 for (i=0; (*p)[i]!='>' && i<TZNAME_MAX; i++)
90 d[i] = (*p)[i];
91 ++*p;
92 } else {
93 for (i=0; ((*p)[i]|32)-'a'<26U && i<TZNAME_MAX; i++)
94 d[i] = (*p)[i];
95 }
96 *p += i;
97 d[i] = 0;
98 }
99
100 #define VEC(...) ((const unsigned char[]){__VA_ARGS__})
101
zi_read32(const unsigned char * z)102 static uint32_t zi_read32(const unsigned char *z)
103 {
104 return (unsigned)z[0]<<24 | z[1]<<16 | z[2]<<8 | z[3];
105 }
106
zi_dotprod(const unsigned char * z,const unsigned char * v,size_t n)107 static size_t zi_dotprod(const unsigned char *z, const unsigned char *v, size_t n)
108 {
109 size_t y;
110 uint32_t x;
111 for (y=0; n; n--, z+=4, v++) {
112 x = zi_read32(z);
113 y += x * *v;
114 }
115 return y;
116 }
117
do_tzset()118 static void do_tzset()
119 {
120 char buf[NAME_MAX+25], *pathname=buf+24;
121 const char *try, *s, *p;
122 const unsigned char *map = 0;
123 size_t i;
124 static const char search[] =
125 "/usr/share/zoneinfo/\0/share/zoneinfo/\0/etc/zoneinfo/\0";
126
127 s = getenv("TZ");
128 if (!s) s = "/etc/localtime";
129 if (!*s) s = __utc;
130
131 if (old_tz && !strcmp(s, old_tz)) return;
132
133 for (i=0; i<5; i++) r0[i] = r1[i] = 0;
134
135 if (zi) __munmap((void *)zi, map_size);
136
137 /* Cache the old value of TZ to check if it has changed. Avoid
138 * free so as not to pull it into static programs. Growth
139 * strategy makes it so free would have minimal benefit anyway. */
140 i = strlen(s);
141 if (i > PATH_MAX+1) s = __utc, i = 3;
142 if (i >= old_tz_size) {
143 old_tz_size *= 2;
144 if (i >= old_tz_size) old_tz_size = i+1;
145 if (old_tz_size > PATH_MAX+2) old_tz_size = PATH_MAX+2;
146 old_tz = malloc(old_tz_size);
147 }
148 if (old_tz) memcpy(old_tz, s, i+1);
149
150 /* Non-suid can use an absolute tzfile pathname or a relative
151 * pathame beginning with "."; in secure mode, only the
152 * standard path will be searched. */
153 if (*s == ':' || ((p=strchr(s, '/')) && !memchr(s, ',', p-s))) {
154 if (*s == ':') s++;
155 if (*s == '/' || *s == '.') {
156 if (!libc.secure || !strcmp(s, "/etc/localtime"))
157 map = __map_file(s, &map_size);
158 } else {
159 size_t l = strlen(s);
160 if (l <= NAME_MAX && !strchr(s, '.')) {
161 memcpy(pathname, s, l+1);
162 pathname[l] = 0;
163 for (try=search; !map && *try; try+=l+1) {
164 l = strlen(try);
165 memcpy(pathname-l, try, l);
166 map = __map_file(pathname-l, &map_size);
167 }
168 }
169 }
170 if (!map) s = __utc;
171 }
172 if (map && (map_size < 44 || memcmp(map, "TZif", 4))) {
173 __munmap((void *)map, map_size);
174 map = 0;
175 s = __utc;
176 }
177
178 zi = map;
179 if (map) {
180 int scale = 2;
181 if (sizeof(time_t) > 4 && map[4]=='2') {
182 size_t skip = zi_dotprod(zi+20, VEC(1,1,8,5,6,1), 6);
183 trans = zi+skip+44+44;
184 scale++;
185 } else {
186 trans = zi+44;
187 }
188 index = trans + (zi_read32(trans-12) << scale);
189 types = index + zi_read32(trans-12);
190 abbrevs = types + 6*zi_read32(trans-8);
191 abbrevs_end = abbrevs + zi_read32(trans-4);
192 if (zi[map_size-1] == '\n') {
193 for (s = (const char *)zi+map_size-2; *s!='\n'; s--);
194 s++;
195 } else {
196 const unsigned char *p;
197 __tzname[0] = __tzname[1] = 0;
198 __daylight = __timezone = dst_off = 0;
199 for (p=types; p<abbrevs; p+=6) {
200 if (!p[4] && !__tzname[0]) {
201 __tzname[0] = (char *)abbrevs + p[5];
202 __timezone = -zi_read32(p);
203 }
204 if (p[4] && !__tzname[1]) {
205 __tzname[1] = (char *)abbrevs + p[5];
206 dst_off = -zi_read32(p);
207 __daylight = 1;
208 }
209 }
210 if (!__tzname[0]) __tzname[0] = __tzname[1];
211 if (!__tzname[0]) __tzname[0] = (char *)__utc;
212 if (!__daylight) {
213 __tzname[1] = __tzname[0];
214 dst_off = __timezone;
215 }
216 return;
217 }
218 }
219
220 if (!s) s = __utc;
221 getname(std_name, &s);
222 __tzname[0] = std_name;
223 __timezone = getoff(&s);
224 getname(dst_name, &s);
225 __tzname[1] = dst_name;
226 if (dst_name[0]) {
227 __daylight = 1;
228 if (*s == '+' || *s=='-' || *s-'0'<10U)
229 dst_off = getoff(&s);
230 else
231 dst_off = __timezone - 3600;
232 } else {
233 __daylight = 0;
234 dst_off = __timezone;
235 }
236
237 if (*s == ',') s++, getrule(&s, r0);
238 if (*s == ',') s++, getrule(&s, r1);
239 }
240
241 /* Search zoneinfo rules to find the one that applies to the given time,
242 * and determine alternate opposite-DST-status rule that may be needed. */
243
scan_trans(long long t,int local,size_t * alt)244 static size_t scan_trans(long long t, int local, size_t *alt)
245 {
246 int scale = 3 - (trans == zi+44);
247 uint64_t x;
248 int off = 0;
249
250 size_t a = 0, n = (index-trans)>>scale, m;
251
252 if (!n) {
253 if (alt) *alt = 0;
254 return 0;
255 }
256
257 /* Binary search for 'most-recent rule before t'. */
258 while (n > 1) {
259 m = a + n/2;
260 x = zi_read32(trans + (m<<scale));
261 if (scale == 3) x = x<<32 | zi_read32(trans + (m<<scale) + 4);
262 else x = (int32_t)x;
263 if (local) off = (int32_t)zi_read32(types + 6 * index[m-1]);
264 if (t - off < (int64_t)x) {
265 n /= 2;
266 } else {
267 a = m;
268 n -= n/2;
269 }
270 }
271
272 /* First and last entry are special. First means to use lowest-index
273 * non-DST type. Last means to apply POSIX-style rule if available. */
274 n = (index-trans)>>scale;
275 if (a == n-1) return -1;
276 if (a == 0) {
277 x = zi_read32(trans + (a<<scale));
278 if (scale == 3) x = x<<32 | zi_read32(trans + (a<<scale) + 4);
279 else x = (int32_t)x;
280 if (local) off = (int32_t)zi_read32(types + 6 * index[a-1]);
281 if (t - off < (int64_t)x) {
282 for (a=0; a<(abbrevs-types)/6; a++) {
283 if (types[6*a+4] != types[4]) break;
284 }
285 if (a == (abbrevs-types)/6) a = 0;
286 if (types[6*a+4]) {
287 *alt = a;
288 return 0;
289 } else {
290 *alt = 0;
291 return a;
292 }
293 }
294 }
295
296 /* Try to find a neighboring opposite-DST-status rule. */
297 if (alt) {
298 if (a && types[6*index[a-1]+4] != types[6*index[a]+4])
299 *alt = index[a-1];
300 else if (a+1<n && types[6*index[a+1]+4] != types[6*index[a]+4])
301 *alt = index[a+1];
302 else
303 *alt = index[a];
304 }
305
306 return index[a];
307 }
308
days_in_month(int m,int is_leap)309 static int days_in_month(int m, int is_leap)
310 {
311 if (m==2) return 28+is_leap;
312 else return 30+((0xad5>>(m-1))&1);
313 }
314
315 /* Convert a POSIX DST rule plus year to seconds since epoch. */
316
rule_to_secs(const int * rule,int year)317 static long long rule_to_secs(const int *rule, int year)
318 {
319 int is_leap;
320 long long t = __year_to_secs(year, &is_leap);
321 int x, m, n, d;
322 if (rule[0]!='M') {
323 x = rule[1];
324 if (rule[0]=='J' && (x < 60 || !is_leap)) x--;
325 t += 86400 * x;
326 } else {
327 m = rule[1];
328 n = rule[2];
329 d = rule[3];
330 t += __month_to_secs(m-1, is_leap);
331 int wday = (int)((t + 4*86400) % (7*86400)) / 86400;
332 int days = d - wday;
333 if (days < 0) days += 7;
334 if (n == 5 && days+28 >= days_in_month(m, is_leap)) n = 4;
335 t += 86400 * (days + 7*(n-1));
336 }
337 t += rule[4];
338 return t;
339 }
340
341 /* Determine the time zone in effect for a given time in seconds since the
342 * epoch. It can be given in local or universal time. The results will
343 * indicate whether DST is in effect at the queried time, and will give both
344 * the GMT offset for the active zone/DST rule and the opposite DST. This
345 * enables a caller to efficiently adjust for the case where an explicit
346 * DST specification mismatches what would be in effect at the time. */
347
__secs_to_zone(long long t,int local,int * isdst,long * offset,long * oppoff,const char ** zonename)348 void __secs_to_zone(long long t, int local, int *isdst, long *offset, long *oppoff, const char **zonename)
349 {
350 LOCK(lock);
351
352 do_tzset();
353
354 if (zi) {
355 size_t alt, i = scan_trans(t, local, &alt);
356 if (i != -1) {
357 *isdst = types[6*i+4];
358 *offset = (int32_t)zi_read32(types+6*i);
359 *zonename = (const char *)abbrevs + types[6*i+5];
360 if (oppoff) *oppoff = (int32_t)zi_read32(types+6*alt);
361 UNLOCK(lock);
362 return;
363 }
364 }
365
366 if (!__daylight) goto std;
367
368 /* FIXME: may be broken if DST changes right at year boundary?
369 * Also, this could be more efficient.*/
370 long long y = t / 31556952 + 70;
371 while (__year_to_secs(y, 0) > t) y--;
372 while (__year_to_secs(y+1, 0) < t) y++;
373
374 long long t0 = rule_to_secs(r0, y);
375 long long t1 = rule_to_secs(r1, y);
376
377 if (!local) {
378 t0 += __timezone;
379 t1 += dst_off;
380 }
381 if (t0 < t1) {
382 if (t >= t0 && t < t1) goto dst;
383 goto std;
384 } else {
385 if (t >= t1 && t < t0) goto std;
386 goto dst;
387 }
388 std:
389 *isdst = 0;
390 *offset = -__timezone;
391 if (oppoff) *oppoff = -dst_off;
392 *zonename = __tzname[0];
393 UNLOCK(lock);
394 return;
395 dst:
396 *isdst = 1;
397 *offset = -dst_off;
398 if (oppoff) *oppoff = -__timezone;
399 *zonename = __tzname[1];
400 UNLOCK(lock);
401 }
402
__tzset()403 static void __tzset()
404 {
405 LOCK(lock);
406 do_tzset();
407 UNLOCK(lock);
408 }
409
410 weak_alias(__tzset, tzset);
411
__tm_to_tzname(const struct tm * tm)412 const char *__tm_to_tzname(const struct tm *tm)
413 {
414 const void *p = tm->__tm_zone;
415 LOCK(lock);
416 do_tzset();
417 if (p != __utc && p != __tzname[0] && p != __tzname[1] &&
418 (!zi || (uintptr_t)p-(uintptr_t)abbrevs >= abbrevs_end - abbrevs))
419 p = "";
420 UNLOCK(lock);
421 return p;
422 }
423