Signed-off-by: Waldemar Kozaczuk <[email protected]>
---
libc/time/__tz.c | 389 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 389 insertions(+)
create mode 100644 libc/time/__tz.c
diff --git a/libc/time/__tz.c b/libc/time/__tz.c
new file mode 100644
index 00000000..a76a7b48
--- /dev/null
+++ b/libc/time/__tz.c
@@ -0,0 +1,389 @@
+#include "time_impl.h"
+#include <stdint.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+#include "libc.h"
+
+long __timezone = 0;
+int __daylight = 0;
+char *__tzname[2] = { 0, 0 };
+
+weak_alias(__timezone, timezone);
+weak_alias(__daylight, daylight);
+weak_alias(__tzname, tzname);
+
+static char std_name[TZNAME_MAX+1];
+static char dst_name[TZNAME_MAX+1];
+
+static int dst_off;
+static int r0[5], r1[5];
+
+static const unsigned char *zi, *trans, *index, *types, *abbrevs;
+static size_t map_size;
+
+static char old_tz_buf[32];
+static char *old_tz = old_tz_buf;
+static size_t old_tz_size = sizeof old_tz_buf;
+
+static int lock[2];
+
+static int getint(const char **p)
+{
+ unsigned x;
+ for (x=0; **p-'0'<10U; (*p)++) x = **p-'0' + 10*x;
+ return x;
+}
+
+static int getsigned(const char **p)
+{
+ if (**p == '-') {
+ ++*p;
+ return -getint(p);
+ }
+ if (**p == '+') ++*p;
+ return getint(p);
+}
+
+static int getoff(const char **p)
+{
+ int off = 3600*getsigned(p);
+ if (**p == ':') {
+ ++*p;
+ off += 60*getint(p);
+ if (**p == ':') {
+ ++*p;
+ off += getint(p);
+ }
+ }
+ return off;
+}
+
+static void getrule(const char **p, int rule[5])
+{
+ int r = rule[0] = **p;
+
+ if (r!='M') {
+ if (r=='J') ++*p;
+ else rule[0] = 0;
+ rule[1] = getint(p);
+ } else {
+ ++*p; rule[1] = getint(p);
+ ++*p; rule[2] = getint(p);
+ ++*p; rule[3] = getint(p);
+ }
+
+ if (**p=='/') {
+ ++*p;
+ rule[4] = getoff(p);
+ } else {
+ rule[4] = 7200;
+ }
+}
+
+static void getname(char *d, const char **p)
+{
+ int i;
+ if (**p == '<') {
+ ++*p;
+ for (i=0; **p!='>' && i<TZNAME_MAX; i++)
+ d[i] = (*p)[i];
+ ++*p;
+ } else {
+ for (i=0; ((*p)[i]|32)-'a'<26U && i<TZNAME_MAX; i++)
+ d[i] = (*p)[i];
+ }
+ *p += i;
+ d[i] = 0;
+}
+
+#define VEC(...) ((const unsigned char[]){__VA_ARGS__})
+
+static uint32_t zi_read32(const unsigned char *z)
+{
+ return (unsigned)z[0]<<24 | z[1]<<16 | z[2]<<8 | z[3];
+}
+
+static size_t zi_dotprod(const unsigned char *z, const unsigned char *v,
size_t n)
+{
+ size_t y;
+ uint32_t x;
+ for (y=0; n; n--, z+=4, v++) {
+ x = zi_read32(z);
+ y += x * *v;
+ }
+ return y;
+}
+
+int __munmap(void *, size_t);
+
+static void do_tzset()
+{
+ char buf[NAME_MAX+25], *pathname=buf+24;
+ const char *try, *s;
+ const unsigned char *map = 0;
+ size_t i;
+ static const char search[] =
+ "/usr/share/zoneinfo/\0/share/zoneinfo/\0/etc/zoneinfo/\0";
+
+ s = getenv("TZ");
+ if (!s) s = "";
+
+ if (old_tz && !strcmp(s, old_tz)) return;
+
+ if (zi) __munmap((void *)zi, map_size);
+
+ /* Cache the old value of TZ to check if it has changed. Avoid
+ * free so as not to pull it into static programs. Growth
+ * strategy makes it so free would have minimal benefit anyway. */
+ i = strlen(s);
+ if (i > PATH_MAX+1) s = "", i = 0;
+ if (i >= old_tz_size) {
+ old_tz_size *= 2;
+ if (i >= old_tz_size) old_tz_size = i+1;
+ if (old_tz_size > PATH_MAX+2) old_tz_size = PATH_MAX+2;
+ old_tz = malloc(old_tz_size);
+ }
+ if (old_tz) memcpy(old_tz, s, i+1);
+
+ if (*s == ':') s++;
+
+ /* Non-suid can use an absolute tzfile pathname or a relative
+ * pathame beginning with "."; in secure mode, only the
+ * standard path will be searched. */
+ if (*s == '/' || *s == '.') {
+ if (!libc.secure) map = __map_file(s, &map_size);
+ } else {
+ for (i=0; s[i] && s[i]!=','; i++) {
+ if (s[i]=='/') {
+ size_t l = strlen(s);
+ if (l > NAME_MAX || strchr(s, '.'))
+ break;
+ memcpy(pathname, s, l+1);
+ pathname[l] = 0;
+ for (try=search; !map && *try; try+=l) {
+ l = strlen(try);
+ memcpy(pathname-l, try, l);
+ map = __map_file(pathname-l, &map_size);
+ }
+ break;
+ }
+ }
+ }
+
+ zi = map;
+ if (map) {
+ int scale = 2;
+ if (sizeof(time_t) > 4 && map[4]=='2') {
+ size_t skip = zi_dotprod(zi, VEC(1,1,8,5,6,1), 6);
+ trans = zi+skip+44+20;
+ scale++;
+ } else {
+ trans = zi+44;
+ }
+ index = trans + (zi_read32(trans-12) << scale);
+ types = index + zi_read32(trans-12);
+ abbrevs = types + 6*zi_read32(trans-8);
+ if (zi[map_size-1] == '\n') {
+ for (s = (const char *)zi+map_size-2; *s!='\n'; s--);
+ s++;
+ } else {
+ s = 0;
+ }
+ }
+
+ if (!s) s = "GMT0";
+ getname(std_name, &s);
+ __tzname[0] = std_name;
+ __timezone = getoff(&s);
+ getname(dst_name, &s);
+ __tzname[1] = dst_name;
+ if (dst_name[0]) {
+ __daylight = 1;
+ if (*s == '+' || *s=='-' || *s-'0'<10U)
+ dst_off = getoff(&s);
+ else
+ dst_off = __timezone - 3600;
+ } else {
+ __daylight = 0;
+ dst_off = 0;
+ }
+
+ if (*s == ',') s++, getrule(&s, r0);
+ if (*s == ',') s++, getrule(&s, r1);
+}
+
+/* Search zoneinfo rules to find the one that applies to the given time,
+ * and determine alternate opposite-DST-status rule that may be needed. */
+
+static size_t scan_trans(long long t, int local, size_t *alt)
+{
+ int scale = 3 - (trans == zi+44);
+ uint64_t x;
+ int off = 0;
+
+ size_t a = 0, n = (index-trans)>>scale, m;
+
+ if (!n) {
+ if (alt) *alt = 0;
+ return 0;
+ }
+
+ /* Binary search for 'most-recent rule before t'. */
+ while (n > 1) {
+ m = a + n/2;
+ x = zi_read32(trans + (m<<scale));
+ if (scale == 3) x = x<<32 | zi_read32(trans + (m<<scale) + 4);
+ else x = (int32_t)x;
+ if (local) off = (int32_t)zi_read32(types + 6 * index[m-1]);
+ if (t - off < (int64_t)x) {
+ n /= 2;
+ } else {
+ a = m;
+ n -= n/2;
+ }
+ }
+
+ /* First and last entry are special. First means to use lowest-index
+ * non-DST type. Last means to apply POSIX-style rule if available. */
+ n = (index-trans)>>scale;
+ if (a == n-1) return -1;
+ if (a == 0) {
+ x = zi_read32(trans + (a<<scale));
+ if (scale == 3) x = x<<32 | zi_read32(trans + (a<<scale) + 4);
+ else x = (int32_t)x;
+ if (local) off = (int32_t)zi_read32(types + 6 * index[a-1]);
+ if (t - off < (int64_t)x) {
+ for (a=0; a<(abbrevs-types)/6; a++) {
+ if (types[6*a+4] != types[4]) break;
+ }
+ if (a == (abbrevs-types)/6) a = 0;
+ if (types[6*a+4]) {
+ *alt = a;
+ return 0;
+ } else {
+ *alt = 0;
+ return a;
+ }
+ }
+ }
+
+ /* Try to find a neighboring opposite-DST-status rule. */
+ if (alt) {
+ if (a && types[6*index[a-1]+4] != types[6*index[a]+4])
+ *alt = index[a-1];
+ else if (a+1<n && types[6*index[a+1]+4] != types[6*index[a]+4])
+ *alt = index[a+1];
+ else
+ *alt = index[a];
+ }
+
+ return index[a];
+}
+
+static int days_in_month(int m, int is_leap)
+{
+ if (m==2) return 28+is_leap;
+ else return 30+((0xad5>>(m-1))&1);
+}
+
+/* Convert a POSIX DST rule plus year to seconds since epoch. */
+
+static long long rule_to_secs(const int *rule, int year)
+{
+ int is_leap;
+ long long t = __year_to_secs(year, &is_leap);
+ int x, m, n, d;
+ if (rule[0]!='M') {
+ x = rule[1];
+ if (rule[0]=='J' && (x < 60 || !is_leap)) x--;
+ t += 86400 * x;
+ } else {
+ m = rule[1];
+ n = rule[2];
+ d = rule[3];
+ t += __month_to_secs(m-1, is_leap);
+ int wday = (int)((t + 4*86400) % (7*86400)) / 86400;
+ int days = d - wday;
+ if (days < 0) days += 7;
+ if (n == 5 && days+28 >= days_in_month(m, is_leap)) n = 4;
+ t += 86400 * (days + 7*(n-1));
+ }
+ t += rule[4];
+ return t;
+}
+
+/* Determine the time zone in effect for a given time in seconds since the
+ * epoch. It can be given in local or universal time. The results will
+ * indicate whether DST is in effect at the queried time, and will give both
+ * the GMT offset for the active zone/DST rule and the opposite DST. This
+ * enables a caller to efficiently adjust for the case where an explicit
+ * DST specification mismatches what would be in effect at the time. */
+
+void __secs_to_zone(long long t, int local, int *isdst, long *offset, long
*oppoff, const char **zonename)
+{
+ LOCK(lock);
+
+ do_tzset();
+
+ if (zi) {
+ size_t alt, i = scan_trans(t, local, &alt);
+ if (i != -1) {
+ *isdst = types[6*i+4];
+ *offset = -(int32_t)zi_read32(types+6*i);
+ *zonename = (const char *)abbrevs + types[6*i+5];
+ if (oppoff) *oppoff = -(int32_t)zi_read32(types+6*alt);
+ UNLOCK(lock);
+ return;
+ }
+ }
+
+ if (!__daylight) goto std;
+
+ /* FIXME: may be broken if DST changes right at year boundary?
+ * Also, this could be more efficient.*/
+ long long y = t / 31556952 + 70;
+ while (__year_to_secs(y, 0) > t) y--;
+ while (__year_to_secs(y+1, 0) < t) y++;
+
+ long long t0 = rule_to_secs(r0, y);
+ long long t1 = rule_to_secs(r1, y);
+
+ if (t0 < t1) {
+ if (!local) {
+ t0 += __timezone;
+ t1 += dst_off;
+ }
+ if (t >= t0 && t < t1) goto dst;
+ goto std;
+ } else {
+ if (!local) {
+ t1 += __timezone;
+ t0 += dst_off;
+ }
+ if (t >= t1 && t < t0) goto std;
+ goto dst;
+ }
+std:
+ *isdst = 0;
+ *offset = __timezone;
+ if (oppoff) *oppoff = dst_off;
+ *zonename = __tzname[0];
+ UNLOCK(lock);
+ return;
+dst:
+ *isdst = 1;
+ *offset = dst_off;
+ if (oppoff) *oppoff = __timezone;
+ *zonename = __tzname[1];
+ UNLOCK(lock);
+}
+
+void __tzset()
+{
+ LOCK(lock);
+ do_tzset();
+ UNLOCK(lock);
+}
+
+weak_alias(__tzset, tzset);
--
2.26.2
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