| /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
| |
| /*** |
| This file is part of systemd. |
| |
| Timezone file reading code from glibc 2.16. |
| |
| Copyright (C) 1991-2012 Free Software Foundation, Inc. |
| Copyright 2012 Kay Sievers |
| |
| systemd is free software; you can redistribute it and/or modify it |
| under the terms of the GNU Lesser General Public License as published by |
| the Free Software Foundation; either version 2.1 of the License, or |
| (at your option) any later version. |
| |
| systemd is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public License |
| along with systemd; If not, see <http://www.gnu.org/licenses/>. |
| ***/ |
| #include <ctype.h> |
| #include <errno.h> |
| #include <stddef.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <string.h> |
| #include <time.h> |
| #include <endian.h> |
| #include <byteswap.h> |
| #include <assert.h> |
| #include <limits.h> |
| #include <unistd.h> |
| #include <stdint.h> |
| #include <stdbool.h> |
| #include <sys/stat.h> |
| |
| #include "time-dst.h" |
| #include "util.h" |
| |
| /* |
| * If tzh_version is '2' or greater, the above is followed by a second instance |
| * of tzhead and a second instance of the data in which each coded transition |
| * time uses 8 rather than 4 chars, then a POSIX-TZ-environment-variable-style |
| * string for use in handling instants after the last transition time stored in |
| * the file * (with nothing between the newlines if there is no POSIX |
| * representation for such instants). |
| */ |
| #define TZ_MAGIC "TZif" |
| struct tzhead { |
| char tzh_magic[4]; /* TZ_MAGIC */ |
| char tzh_version[1]; /* '\0' or '2' as of 2005 */ |
| char tzh_reserved[15]; /* reserved--must be zero */ |
| char tzh_ttisgmtcnt[4]; /* coded number of trans. time flags */ |
| char tzh_ttisstdcnt[4]; /* coded number of trans. time flags */ |
| char tzh_leapcnt[4]; /* coded number of leap seconds */ |
| char tzh_timecnt[4]; /* coded number of transition times */ |
| char tzh_typecnt[4]; /* coded number of local time types */ |
| char tzh_charcnt[4]; /* coded number of abbr. chars */ |
| }; |
| |
| struct ttinfo { |
| long int offset; /* Seconds east of GMT. */ |
| unsigned char isdst; /* Used to set tm_isdst. */ |
| unsigned char idx; /* Index into `zone_names'. */ |
| unsigned char isstd; /* Transition times are in standard time. */ |
| unsigned char isgmt; /* Transition times are in GMT. */ |
| }; |
| |
| struct leap { |
| time_t transition; /* Time the transition takes effect. */ |
| long int change; /* Seconds of correction to apply. */ |
| }; |
| |
| static inline int decode(const void *ptr) { |
| return be32toh(*(int *)ptr); |
| } |
| |
| static inline int64_t decode64(const void *ptr) { |
| return be64toh(*(int64_t *)ptr); |
| } |
| |
| int time_get_dst(time_t date, const char *tzfile, |
| time_t *switch_cur, char **zone_cur, bool *dst_cur, |
| time_t *switch_next, int *delta_next, char **zone_next, bool *dst_next) { |
| unsigned char *type_idxs = 0; |
| size_t num_types = 0; |
| struct ttinfo *types = NULL; |
| char *zone_names = NULL; |
| struct stat st; |
| size_t num_isstd, num_isgmt; |
| struct tzhead tzhead; |
| size_t chars; |
| size_t i; |
| size_t total_size; |
| size_t types_idx; |
| int trans_width = 4; |
| size_t tzspec_len; |
| size_t num_leaps; |
| size_t lo, hi; |
| size_t num_transitions = 0; |
| _cleanup_free_ time_t *transitions = NULL; |
| _cleanup_fclose_ FILE *f; |
| |
| f = fopen(tzfile, "re"); |
| if (f == NULL) |
| return -errno; |
| |
| if (fstat(fileno(f), &st) < 0) |
| return -errno; |
| |
| read_again: |
| if (fread((void *)&tzhead, sizeof(tzhead), 1, f) != 1 || |
| memcmp(tzhead.tzh_magic, TZ_MAGIC, sizeof(tzhead.tzh_magic)) != 0) |
| return -EINVAL; |
| |
| num_transitions = (size_t)decode(tzhead.tzh_timecnt); |
| num_types = (size_t)decode(tzhead.tzh_typecnt); |
| chars = (size_t)decode(tzhead.tzh_charcnt); |
| num_leaps = (size_t)decode(tzhead.tzh_leapcnt); |
| num_isstd = (size_t)decode(tzhead.tzh_ttisstdcnt); |
| num_isgmt = (size_t)decode(tzhead.tzh_ttisgmtcnt); |
| |
| /* For platforms with 64-bit time_t we use the new format if available. */ |
| if (sizeof(time_t) == 8 && trans_width == 4 && tzhead.tzh_version[0] != '\0') { |
| size_t to_skip; |
| |
| /* We use the 8-byte format. */ |
| trans_width = 8; |
| |
| /* Position the stream before the second header. */ |
| to_skip = (num_transitions * (4 + 1) |
| + num_types * 6 |
| + chars |
| + num_leaps * 8 + num_isstd + num_isgmt); |
| if (fseek(f, to_skip, SEEK_CUR) != 0) |
| return -EINVAL; |
| |
| goto read_again; |
| } |
| |
| if (num_transitions > ((SIZE_MAX - (__alignof__(struct ttinfo) - 1)) / (sizeof(time_t) + 1))) |
| return -EINVAL; |
| |
| total_size = num_transitions * (sizeof(time_t) + 1); |
| total_size = ((total_size + __alignof__(struct ttinfo) - 1) & ~(__alignof__(struct ttinfo) - 1)); |
| types_idx = total_size; |
| if (num_leaps > (SIZE_MAX - total_size) / sizeof(struct ttinfo)) |
| return -EINVAL; |
| |
| total_size += num_types * sizeof(struct ttinfo); |
| if (chars > SIZE_MAX - total_size) |
| return -EINVAL; |
| |
| total_size += chars; |
| if (__alignof__(struct leap) - 1 > SIZE_MAX - total_size) |
| return -EINVAL; |
| |
| total_size = ((total_size + __alignof__(struct leap) - 1) & ~(__alignof__(struct leap) - 1)); |
| if (num_leaps > (SIZE_MAX - total_size) / sizeof(struct leap)) |
| return -EINVAL; |
| |
| total_size += num_leaps * sizeof(struct leap); |
| tzspec_len = 0; |
| if (sizeof(time_t) == 8 && trans_width == 8) { |
| off_t rem = st.st_size - ftello(f); |
| |
| if (rem < 0 || (size_t) rem < (num_transitions * (8 + 1) + num_types * 6 + chars)) |
| return -EINVAL; |
| tzspec_len = (size_t) rem - (num_transitions * (8 + 1) + num_types * 6 + chars); |
| if (num_leaps > SIZE_MAX / 12 || tzspec_len < num_leaps * 12) |
| return -EINVAL; |
| tzspec_len -= num_leaps * 12; |
| if (tzspec_len < num_isstd) |
| return -EINVAL; |
| tzspec_len -= num_isstd; |
| if (tzspec_len == 0 || tzspec_len - 1 < num_isgmt) |
| return -EINVAL; |
| tzspec_len -= num_isgmt + 1; |
| if (SIZE_MAX - total_size < tzspec_len) |
| return -EINVAL; |
| } |
| |
| transitions = malloc0(total_size + tzspec_len); |
| if (transitions == NULL) |
| return -EINVAL; |
| |
| type_idxs = (unsigned char *)transitions + (num_transitions |
| * sizeof(time_t)); |
| types = (struct ttinfo *)((char *)transitions + types_idx); |
| zone_names = (char *)types + num_types * sizeof(struct ttinfo); |
| |
| if (sizeof(time_t) == 4 || trans_width == 8) { |
| if (fread(transitions, trans_width + 1, num_transitions, f) != num_transitions) |
| return -EINVAL; |
| } else { |
| if (fread(transitions, 4, num_transitions, f) != num_transitions || |
| fread(type_idxs, 1, num_transitions, f) != num_transitions) |
| return -EINVAL; |
| } |
| |
| /* Check for bogus indices in the data file, so we can hereafter |
| safely use type_idxs[T] as indices into `types' and never crash. */ |
| for (i = 0; i < num_transitions; ++i) |
| if (type_idxs[i] >= num_types) |
| return -EINVAL; |
| |
| if (__BYTE_ORDER == __BIG_ENDIAN ? sizeof(time_t) == 8 && trans_width == 4 |
| : sizeof(time_t) == 4 || trans_width == 4) { |
| /* Decode the transition times, stored as 4-byte integers in |
| network (big-endian) byte order. We work from the end of |
| the array so as not to clobber the next element to be |
| processed when sizeof (time_t) > 4. */ |
| i = num_transitions; |
| while (i-- > 0) |
| transitions[i] = decode((char *)transitions + i * 4); |
| } else if (__BYTE_ORDER != __BIG_ENDIAN && sizeof(time_t) == 8) { |
| /* Decode the transition times, stored as 8-byte integers in |
| network (big-endian) byte order. */ |
| for (i = 0; i < num_transitions; ++i) |
| transitions[i] = decode64((char *)transitions + i * 8); |
| } |
| |
| for (i = 0; i < num_types; ++i) { |
| unsigned char x[4]; |
| int c; |
| |
| if (fread(x, 1, sizeof(x), f) != sizeof(x)) |
| return -EINVAL; |
| c = getc(f); |
| if ((unsigned int)c > 1u) |
| return -EINVAL; |
| types[i].isdst = c; |
| c = getc(f); |
| if ((size_t) c > chars) |
| /* Bogus index in data file. */ |
| return -EINVAL; |
| types[i].idx = c; |
| types[i].offset = (long int)decode(x); |
| } |
| |
| if (fread(zone_names, 1, chars, f) != chars) |
| return -EINVAL; |
| |
| for (i = 0; i < num_isstd; ++i) { |
| int c = getc(f); |
| if (c == EOF) |
| return -EINVAL; |
| types[i].isstd = c != 0; |
| } |
| |
| while (i < num_types) |
| types[i++].isstd = 0; |
| |
| for (i = 0; i < num_isgmt; ++i) { |
| int c = getc(f); |
| if (c == EOF) |
| return -EINVAL; |
| types[i].isgmt = c != 0; |
| } |
| |
| while (i < num_types) |
| types[i++].isgmt = 0; |
| |
| if (num_transitions == 0) |
| return -EINVAL; |
| |
| if (date < transitions[0] || date >= transitions[num_transitions - 1]) |
| return -EINVAL; |
| |
| /* Find the first transition after TIMER, and |
| then pick the type of the transition before it. */ |
| lo = 0; |
| hi = num_transitions - 1; |
| |
| /* Assume that DST is changing twice a year and guess initial |
| search spot from it. |
| Half of a gregorian year has on average 365.2425 * 86400 / 2 |
| = 15778476 seconds. */ |
| i = (transitions[num_transitions - 1] - date) / 15778476; |
| if (i < num_transitions) { |
| i = num_transitions - 1 - i; |
| if (date < transitions[i]) { |
| if (i < 10 || date >= transitions[i - 10]) { |
| /* Linear search. */ |
| while (date < transitions[i - 1]) |
| i--; |
| goto found; |
| } |
| hi = i - 10; |
| } else { |
| if (i + 10 >= num_transitions || date < transitions[i + 10]) { |
| /* Linear search. */ |
| while (date >= transitions[i]) |
| i++; |
| goto found; |
| } |
| lo = i + 10; |
| } |
| } |
| |
| /* Binary search. */ |
| while (lo + 1 < hi) { |
| i = (lo + hi) / 2; |
| if (date < transitions[i]) |
| hi = i; |
| else |
| lo = i; |
| } |
| i = hi; |
| |
| found: |
| if (switch_cur) |
| *switch_cur = transitions[i-1]; |
| if (zone_cur) |
| *zone_cur = strdup(&zone_names[types[type_idxs[i - 1]].idx]); |
| if (dst_cur) |
| *dst_cur = types[type_idxs[i-1]].isdst; |
| |
| if (switch_next) |
| *switch_next = transitions[i]; |
| if (delta_next) |
| *delta_next = (types[type_idxs[i]].offset - types[type_idxs[i-1]].offset) / 60; |
| if (zone_next) |
| *zone_next = strdup(&zone_names[types[type_idxs[i]].idx]); |
| if (dst_next) |
| *dst_next = types[type_idxs[i]].isdst; |
| |
| return 0; |
| } |