--- /dev/null
+/*-*- 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"
+
+/*
+ * 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, char **zone_next, bool *dst_next) {
+ time_t *transitions = NULL;
+ size_t num_transitions = 0;
+ 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;
+ FILE *f;
+ 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;
+ int err = 0;
+
+ f = fopen(tzfile, "re");
+ if (f == NULL)
+ return -errno;
+
+ if (fstat(fileno(f), &st) < 0) {
+ err = -errno;
+ fclose(f);
+ return err;
+ }
+
+read_again:
+ if (fread((void *)&tzhead, sizeof(tzhead), 1, f) != 1 ||
+ memcmp(tzhead.tzh_magic, TZ_MAGIC, sizeof(tzhead.tzh_magic)) != 0)
+ goto lose;
+
+ 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)
+ goto lose;
+
+ goto read_again;
+ }
+
+ if (num_transitions > ((SIZE_MAX - (__alignof__(struct ttinfo) - 1)) / (sizeof(time_t) + 1)))
+ goto lose;
+
+ 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))
+ goto lose;
+
+ total_size += num_types * sizeof(struct ttinfo);
+ if (chars > SIZE_MAX - total_size)
+ goto lose;
+
+ total_size += chars;
+ if (__alignof__(struct leap) - 1 > SIZE_MAX - total_size)
+ goto lose;
+
+ total_size = ((total_size + __alignof__(struct leap) - 1) & ~(__alignof__(struct leap) - 1));
+ if (num_leaps > (SIZE_MAX - total_size) / sizeof(struct leap))
+ goto lose;
+
+ 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))
+ goto lose;
+ tzspec_len = (size_t) rem - (num_transitions * (8 + 1) + num_types * 6 + chars);
+ if (num_leaps > SIZE_MAX / 12 || tzspec_len < num_leaps * 12)
+ goto lose;
+ tzspec_len -= num_leaps * 12;
+ if (tzspec_len < num_isstd)
+ goto lose;
+ tzspec_len -= num_isstd;
+ if (tzspec_len == 0 || tzspec_len - 1 < num_isgmt)
+ goto lose;
+ tzspec_len -= num_isgmt + 1;
+ if (SIZE_MAX - total_size < tzspec_len)
+ goto lose;
+ }
+
+ transitions = (time_t *)calloc(total_size + tzspec_len, 1);
+ if (transitions == NULL)
+ goto lose;
+
+ 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)
+ goto lose;
+ } else {
+ if (fread(transitions, 4, num_transitions, f) != num_transitions ||
+ fread(type_idxs, 1, num_transitions, f) != num_transitions)
+ goto lose;
+ }
+
+ /* 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)
+ goto lose;
+
+ if ((BYTE_ORDER != BIG_ENDIAN && (sizeof(time_t) == 4 || trans_width == 4)) ||
+ (BYTE_ORDER == BIG_ENDIAN && sizeof(time_t) == 8 && 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))
+ goto lose;
+ c = getc(f);
+ if ((unsigned int)c > 1u)
+ goto lose;
+ types[i].isdst = c;
+ c = getc(f);
+ if ((size_t) c > chars)
+ /* Bogus index in data file. */
+ goto lose;
+ types[i].idx = c;
+ types[i].offset = (long int)decode(x);
+ }
+
+ if (fread(zone_names, 1, chars, f) != chars)
+ goto lose;
+
+ for (i = 0; i < num_isstd; ++i) {
+ int c = getc(f);
+ if (c == EOF)
+ goto lose;
+ 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)
+ goto lose;
+ types[i].isgmt = c != 0;
+ }
+
+ while (i < num_types)
+ types[i++].isgmt = 0;
+
+ if (num_transitions == 0)
+ goto lose;
+
+ if (date < transitions[0] || date >= transitions[num_transitions - 1])
+ goto lose;
+
+ /* 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 (zone_next)
+ *zone_next = strdup(&zone_names[types[type_idxs[i]].idx]);
+ if (dst_next)
+ *dst_next = types[type_idxs[i]].isdst;
+
+ free(transitions);
+ fclose(f);
+ return 0;
+lose:
+ free(transitions);
+ fclose(f);
+ return err;
+}
~ianmdlvl / elogind.git / commitdiff