Can you please explain the motivation of this?
I thought maybe you are copying it instead of just enabling it in the
Makefile because you needed to change it - but the I don't see changes in
the next patches.
So what's the motivation?
--
Nadav Har'El
n...@scylladb.com
On Wed, Aug 26, 2020 at 6:54 AM Waldemar Kozaczuk <jwkozac...@gmail.com>
wrote:
> Signed-off-by: Waldemar Kozaczuk <jwkozac...@gmail.com>
> ---
> 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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