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musl/src/time/__tz.c

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the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
#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];
fix strftime handling of time zone data this may need further revision in the future, since POSIX is rather unclear on the requirements, and is designed around the assumption of POSIX TZ specifiers which are not sufficiently powerful to represent real-world timezones (this is why zoneinfo support was added). the basic issue is that strftime gets the string and numeric offset for the timezone from the extra fields in struct tm, which are initialized when calling localtime/gmtime/etc. however, a conforming application might have created its own struct tm without initializing these fields, in which case using __tm_zone (a pointer) could crash. other zoneinfo-based implementations simply check for a null pointer, but otherwise can still crash of the field contains junk. simply ignoring __tm_zone and using tzname[] would "work" but would give incorrect results in time zones with more complex rules. I feel like this would lower the quality of implementation. instead, simply validate __tm_zone: unless it points to one of the zone name strings managed by the timezone system, assume it's invalid. this commit also fixes several other minor bugs with formatting: tm_isdst being negative is required to suppress printing of the zone formats, and %z was using the wrong format specifiers since the type of val was changed, resulting in bogus output.
2013-08-24 12:59:02 -04:00
const char __gmt[] = "GMT";
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
static int dst_off;
static int r0[5], r1[5];
fix strftime handling of time zone data this may need further revision in the future, since POSIX is rather unclear on the requirements, and is designed around the assumption of POSIX TZ specifiers which are not sufficiently powerful to represent real-world timezones (this is why zoneinfo support was added). the basic issue is that strftime gets the string and numeric offset for the timezone from the extra fields in struct tm, which are initialized when calling localtime/gmtime/etc. however, a conforming application might have created its own struct tm without initializing these fields, in which case using __tm_zone (a pointer) could crash. other zoneinfo-based implementations simply check for a null pointer, but otherwise can still crash of the field contains junk. simply ignoring __tm_zone and using tzname[] would "work" but would give incorrect results in time zones with more complex rules. I feel like this would lower the quality of implementation. instead, simply validate __tm_zone: unless it points to one of the zone name strings managed by the timezone system, assume it's invalid. this commit also fixes several other minor bugs with formatting: tm_isdst being negative is required to suppress printing of the zone formats, and %z was using the wrong format specifiers since the type of val was changed, resulting in bogus output.
2013-08-24 12:59:02 -04:00
static const unsigned char *zi, *trans, *index, *types, *abbrevs, *abbrevs_end;
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
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;
make all objects used with atomic operations volatile the memory model we use internally for atomics permits plain loads of values which may be subject to concurrent modification without requiring that a special load function be used. since a compiler is free to make transformations that alter the number of loads or the way in which loads are performed, the compiler is theoretically free to break this usage. the most obvious concern is with atomic cas constructs: something of the form tmp=*p;a_cas(p,tmp,f(tmp)); could be transformed to a_cas(p,*p,f(*p)); where the latter is intended to show multiple loads of *p whose resulting values might fail to be equal; this would break the atomicity of the whole operation. but even more fundamental breakage is possible. with the changes being made now, objects that may be modified by atomics are modeled as volatile, and the atomic operations performed on them by other threads are modeled as asynchronous stores by hardware which happens to be acting on the request of another thread. such modeling of course does not itself address memory synchronization between cores/cpus, but that aspect was already handled. this all seems less than ideal, but it's the best we can do without mandating a C11 compiler and using the C11 model for atomics. in the case of pthread_once_t, the ABI type of the underlying object is not volatile-qualified. so we are assuming that accessing the object through a volatile-qualified lvalue via casts yields volatile access semantics. the language of the C standard is somewhat unclear on this matter, but this is an assumption the linux kernel also makes, and seems to be the correct interpretation of the standard.
2015-03-03 22:50:02 -05:00
static volatile int lock[2];
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
static int getint(const char **p)
{
unsigned x;
for (x=0; **p-'0'<10U; (*p)++) x = **p-'0' + 10*x;
return x;
}
fix handling of negative offsets in timezone spec strings previously, the hours were considered as a signed quantity while minutes and seconds were always treated as positive offsets. however, semantically the '-' sign should negate the whole hh:mm:ss offset. this bug only affected timezones east of GMT with non-whole-hours offsets, such as those used in India and Nepal.
2014-10-09 23:44:02 -04:00
static int getoff(const char **p)
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
{
fix handling of negative offsets in timezone spec strings previously, the hours were considered as a signed quantity while minutes and seconds were always treated as positive offsets. however, semantically the '-' sign should negate the whole hh:mm:ss offset. this bug only affected timezones east of GMT with non-whole-hours offsets, such as those used in India and Nepal.
2014-10-09 23:44:02 -04:00
int neg = 0;
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
if (**p == '-') {
++*p;
fix handling of negative offsets in timezone spec strings previously, the hours were considered as a signed quantity while minutes and seconds were always treated as positive offsets. however, semantically the '-' sign should negate the whole hh:mm:ss offset. this bug only affected timezones east of GMT with non-whole-hours offsets, such as those used in India and Nepal.
2014-10-09 23:44:02 -04:00
neg = 1;
} else if (**p == '+') {
++*p;
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
}
fix handling of negative offsets in timezone spec strings previously, the hours were considered as a signed quantity while minutes and seconds were always treated as positive offsets. however, semantically the '-' sign should negate the whole hh:mm:ss offset. this bug only affected timezones east of GMT with non-whole-hours offsets, such as those used in India and Nepal.
2014-10-09 23:44:02 -04:00
int off = 3600*getint(p);
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
if (**p == ':') {
++*p;
off += 60*getint(p);
if (**p == ':') {
++*p;
off += getint(p);
}
}
fix handling of negative offsets in timezone spec strings previously, the hours were considered as a signed quantity while minutes and seconds were always treated as positive offsets. however, semantically the '-' sign should negate the whole hh:mm:ss offset. this bug only affected timezones east of GMT with non-whole-hours offsets, such as those used in India and Nepal.
2014-10-09 23:44:02 -04:00
return neg ? -off : off;
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
}
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;
allow zoneinfo-path-relative filenames with no slashes in TZ variable since the form TZ=name is reserved for POSIX-form time zone strings, TZ=:name needs to be used when the zoneinfo filename is in the top-level zoneinfo directory and therefore does not contain a slash. previously the leading colon was merely dropped, making it impossible to access such zones without a full absolute pathname. changes based on patch by Timo Teräs.
2014-04-21 18:11:42 -04:00
const char *try, *s, *p;
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
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");
treat empty TZ environment variable as GMT rather than default this improves compatibility with the behavior of other systems and with some applications which set an empty TZ var to disable use of local time by mktime, etc.
2015-07-06 22:13:11 +00:00
if (!s) s = "/etc/localtime";
if (!*s) s = __gmt;
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
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);
fix handling of overly-long TZ environment variable values the rest of the code is not prepared to handle an empty TZ string, so falling back to __gmt ("GMT"), just as if TZ had been blank or unset, is the preferable action.
2013-11-08 20:50:59 -05:00
if (i > PATH_MAX+1) s = __gmt, i = 3;
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
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);
/* Non-suid can use an absolute tzfile pathname or a relative
* pathame beginning with "."; in secure mode, only the
* standard path will be searched. */
allow zoneinfo-path-relative filenames with no slashes in TZ variable since the form TZ=name is reserved for POSIX-form time zone strings, TZ=:name needs to be used when the zoneinfo filename is in the top-level zoneinfo directory and therefore does not contain a slash. previously the leading colon was merely dropped, making it impossible to access such zones without a full absolute pathname. changes based on patch by Timo Teräs.
2014-04-21 18:11:42 -04:00
if (*s == ':' || ((p=strchr(s, '/')) && !memchr(s, ',', p-s))) {
if (*s == ':') s++;
if (*s == '/' || *s == '.') {
use default timezone from /etc/localtime if $TZ is unset/blank the way this is implemented, it also allows explicit setting of TZ=/etc/localtime even for suid programs. this is not a problem because /etc/localtime is a trusted path, much like the trusted zoneinfo search path.
2014-06-06 20:46:05 -04:00
if (!libc.secure || !strcmp(s, "/etc/localtime"))
map = __map_file(s, &map_size);
allow zoneinfo-path-relative filenames with no slashes in TZ variable since the form TZ=name is reserved for POSIX-form time zone strings, TZ=:name needs to be used when the zoneinfo filename is in the top-level zoneinfo directory and therefore does not contain a slash. previously the leading colon was merely dropped, making it impossible to access such zones without a full absolute pathname. changes based on patch by Timo Teräs.
2014-04-21 18:11:42 -04:00
} else {
size_t l = strlen(s);
if (l <= NAME_MAX && !strchr(s, '.')) {
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
memcpy(pathname, s, l+1);
pathname[l] = 0;
timezone parser: fix iteration over search dir paths try+l points to \0, so only one iteration was ever tried.
2013-11-04 17:07:28 +00:00
for (try=search; !map && *try; try+=l+1) {
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
l = strlen(try);
memcpy(pathname-l, try, l);
map = __map_file(pathname-l, &map_size);
}
}
}
do not try to interpret implementation specific strings as tz definition
2014-04-22 21:55:20 +03:00
if (!map) s = __gmt;
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
}
perform minimal sanity checks on zoneinfo files loaded via TZ variable previously, setting TZ to the pathname of a file which was not a valid zoneinfo file would usually cause programs using local time zone based operations to crash. the new code checks the file size and magic at the beginning of the file, which seems sufficient to prevent accidental misconfiguration from causing crashes. attempting to make fully-robust validation would be futile unless we wanted to drop use of mmap (shared zoneinfo) and instead read it into a local buffer, since such validation would be subject to race conditions with modification of the file.
2014-04-22 20:09:56 -04:00
if (map && (map_size < 44 || memcmp(map, "TZif", 4))) {
__munmap((void *)map, map_size);
map = 0;
s = __gmt;
}
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
zi = map;
if (map) {
int scale = 2;
if (sizeof(time_t) > 4 && map[4]=='2') {
fix timezone parser code crashing on 64bit sys if sizeof(time_t) == 8, this code path was missing the correct offset into the zoneinfo file, using the header magic to do offset calculations. the 6 32bit fields to be read start at offset 20.
2013-11-04 15:13:21 +00:00
size_t skip = zi_dotprod(zi+20, VEC(1,1,8,5,6,1), 6);
timezone parser: fix offset to transition table in 64bit code path we need to skip to the second TZif header, which starts at skip+44, and then skip another header (20 bytes) plus the following 6 32bit values.
2013-11-04 15:57:51 +00:00
trans = zi+skip+44+44;
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
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);
fix strftime handling of time zone data this may need further revision in the future, since POSIX is rather unclear on the requirements, and is designed around the assumption of POSIX TZ specifiers which are not sufficiently powerful to represent real-world timezones (this is why zoneinfo support was added). the basic issue is that strftime gets the string and numeric offset for the timezone from the extra fields in struct tm, which are initialized when calling localtime/gmtime/etc. however, a conforming application might have created its own struct tm without initializing these fields, in which case using __tm_zone (a pointer) could crash. other zoneinfo-based implementations simply check for a null pointer, but otherwise can still crash of the field contains junk. simply ignoring __tm_zone and using tzname[] would "work" but would give incorrect results in time zones with more complex rules. I feel like this would lower the quality of implementation. instead, simply validate __tm_zone: unless it points to one of the zone name strings managed by the timezone system, assume it's invalid. this commit also fixes several other minor bugs with formatting: tm_isdst being negative is required to suppress printing of the zone formats, and %z was using the wrong format specifiers since the type of val was changed, resulting in bogus output.
2013-08-24 12:59:02 -04:00
abbrevs_end = abbrevs + zi_read32(trans-4);
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
if (zi[map_size-1] == '\n') {
for (s = (const char *)zi+map_size-2; *s!='\n'; s--);
s++;
} else {
properly fill in tzname[] for old (pre-64-bit-format) zoneinfo files in this case, the first standard-time and first daylight-time rules should be taken as the "default" ones to expose.
2013-08-24 13:11:18 -04:00
const unsigned char *p;
__tzname[0] = __tzname[1] = 0;
__daylight = __timezone = dst_off = 0;
for (i=0; i<5; i++) r0[i] = r1[i] = 0;
for (p=types; p<abbrevs; p+=6) {
if (!p[4] && !__tzname[0]) {
__tzname[0] = (char *)abbrevs + p[5];
__timezone = -zi_read32(p);
}
if (p[4] && !__tzname[1]) {
__tzname[1] = (char *)abbrevs + p[5];
dst_off = -zi_read32(p);
__daylight = 1;
}
}
if (!__tzname[0]) __tzname[0] = __tzname[1];
if (!__tzname[0]) __tzname[0] = (char *)__gmt;
if (!__daylight) {
__tzname[1] = __tzname[0];
dst_off = __timezone;
}
return;
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
}
}
fix strftime handling of time zone data this may need further revision in the future, since POSIX is rather unclear on the requirements, and is designed around the assumption of POSIX TZ specifiers which are not sufficiently powerful to represent real-world timezones (this is why zoneinfo support was added). the basic issue is that strftime gets the string and numeric offset for the timezone from the extra fields in struct tm, which are initialized when calling localtime/gmtime/etc. however, a conforming application might have created its own struct tm without initializing these fields, in which case using __tm_zone (a pointer) could crash. other zoneinfo-based implementations simply check for a null pointer, but otherwise can still crash of the field contains junk. simply ignoring __tm_zone and using tzname[] would "work" but would give incorrect results in time zones with more complex rules. I feel like this would lower the quality of implementation. instead, simply validate __tm_zone: unless it points to one of the zone name strings managed by the timezone system, assume it's invalid. this commit also fixes several other minor bugs with formatting: tm_isdst being negative is required to suppress printing of the zone formats, and %z was using the wrong format specifiers since the type of val was changed, resulting in bogus output.
2013-08-24 12:59:02 -04:00
if (!s) s = __gmt;
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
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];
match historical behavior for tm_gmtoff member of struct tm tm_gmtoff is a nonstandard field, but on historical systems which have this field, it stores the offset of the local time zone from GMT or UTC. this is the opposite of the POSIX extern long timezone object and the offsets used in POSIX-form TZ strings, which represent the offset from local time to UTC. previously we were storing these negated offsets in tm_gmtoff too. programs which only used this field indirectly via strftime were not affected since strftime performed the negation for presentation. however, some programs and libraries accesse tm_gmtoff directly and were obtaining negated time zone offsets.
2015-08-13 17:28:39 +02:00
*offset = (int32_t)zi_read32(types+6*i);
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
*zonename = (const char *)abbrevs + types[6*i+5];
match historical behavior for tm_gmtoff member of struct tm tm_gmtoff is a nonstandard field, but on historical systems which have this field, it stores the offset of the local time zone from GMT or UTC. this is the opposite of the POSIX extern long timezone object and the offsets used in POSIX-form TZ strings, which represent the offset from local time to UTC. previously we were storing these negated offsets in tm_gmtoff too. programs which only used this field indirectly via strftime were not affected since strftime performed the negation for presentation. however, some programs and libraries accesse tm_gmtoff directly and were obtaining negated time zone offsets.
2015-08-13 17:28:39 +02:00
if (oppoff) *oppoff = (int32_t)zi_read32(types+6*alt);
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
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;
match historical behavior for tm_gmtoff member of struct tm tm_gmtoff is a nonstandard field, but on historical systems which have this field, it stores the offset of the local time zone from GMT or UTC. this is the opposite of the POSIX extern long timezone object and the offsets used in POSIX-form TZ strings, which represent the offset from local time to UTC. previously we were storing these negated offsets in tm_gmtoff too. programs which only used this field indirectly via strftime were not affected since strftime performed the negation for presentation. however, some programs and libraries accesse tm_gmtoff directly and were obtaining negated time zone offsets.
2015-08-13 17:28:39 +02:00
*offset = -__timezone;
if (oppoff) *oppoff = -dst_off;
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
*zonename = __tzname[0];
UNLOCK(lock);
return;
dst:
*isdst = 1;
match historical behavior for tm_gmtoff member of struct tm tm_gmtoff is a nonstandard field, but on historical systems which have this field, it stores the offset of the local time zone from GMT or UTC. this is the opposite of the POSIX extern long timezone object and the offsets used in POSIX-form TZ strings, which represent the offset from local time to UTC. previously we were storing these negated offsets in tm_gmtoff too. programs which only used this field indirectly via strftime were not affected since strftime performed the negation for presentation. however, some programs and libraries accesse tm_gmtoff directly and were obtaining negated time zone offsets.
2015-08-13 17:28:39 +02:00
*offset = -dst_off;
if (oppoff) *oppoff = -__timezone;
the big time handling overhaul this commit has two major user-visible parts: zoneinfo-format time zones are now supported, and overflow handling is intended to be complete in the sense that all functions return a correct result if and only if the result fits in the destination type, and otherwise return an error. also, some noticable bugs in the way DST detection and normalization worked have been fixed, and performance may be better than before, but it has not been tested.
2013-07-17 05:24:50 -04:00
*zonename = __tzname[1];
UNLOCK(lock);
}
void __tzset()
{
LOCK(lock);
do_tzset();
UNLOCK(lock);
}
weak_alias(__tzset, tzset);
fix strftime handling of time zone data this may need further revision in the future, since POSIX is rather unclear on the requirements, and is designed around the assumption of POSIX TZ specifiers which are not sufficiently powerful to represent real-world timezones (this is why zoneinfo support was added). the basic issue is that strftime gets the string and numeric offset for the timezone from the extra fields in struct tm, which are initialized when calling localtime/gmtime/etc. however, a conforming application might have created its own struct tm without initializing these fields, in which case using __tm_zone (a pointer) could crash. other zoneinfo-based implementations simply check for a null pointer, but otherwise can still crash of the field contains junk. simply ignoring __tm_zone and using tzname[] would "work" but would give incorrect results in time zones with more complex rules. I feel like this would lower the quality of implementation. instead, simply validate __tm_zone: unless it points to one of the zone name strings managed by the timezone system, assume it's invalid. this commit also fixes several other minor bugs with formatting: tm_isdst being negative is required to suppress printing of the zone formats, and %z was using the wrong format specifiers since the type of val was changed, resulting in bogus output.
2013-08-24 12:59:02 -04:00
const char *__tm_to_tzname(const struct tm *tm)
{
const void *p = tm->__tm_zone;
LOCK(lock);
do_tzset();
minor fix to tz name checking if a zoneinfo file is not (or is no longer) in use, don't check the abbrevs pointers, which may be invalid.
2013-08-24 13:10:01 -04:00
if (p != __gmt && p != __tzname[0] && p != __tzname[1] &&
(!zi || (uintptr_t)p-(uintptr_t)abbrevs >= abbrevs_end - abbrevs))
fix strftime handling of time zone data this may need further revision in the future, since POSIX is rather unclear on the requirements, and is designed around the assumption of POSIX TZ specifiers which are not sufficiently powerful to represent real-world timezones (this is why zoneinfo support was added). the basic issue is that strftime gets the string and numeric offset for the timezone from the extra fields in struct tm, which are initialized when calling localtime/gmtime/etc. however, a conforming application might have created its own struct tm without initializing these fields, in which case using __tm_zone (a pointer) could crash. other zoneinfo-based implementations simply check for a null pointer, but otherwise can still crash of the field contains junk. simply ignoring __tm_zone and using tzname[] would "work" but would give incorrect results in time zones with more complex rules. I feel like this would lower the quality of implementation. instead, simply validate __tm_zone: unless it points to one of the zone name strings managed by the timezone system, assume it's invalid. this commit also fixes several other minor bugs with formatting: tm_isdst being negative is required to suppress printing of the zone formats, and %z was using the wrong format specifiers since the type of val was changed, resulting in bogus output.
2013-08-24 12:59:02 -04:00
p = "";
UNLOCK(lock);
return p;
}
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