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/****************************************************************************
* bfs *
* Copyright (C) 2020 Tavian Barnes <tavianator@tavianator.com> *
* *
* Permission to use, copy, modify, and/or distribute this software for any *
* purpose with or without fee is hereby granted. *
* *
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES *
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF *
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR *
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES *
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN *
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF *
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. *
****************************************************************************/
#include "time.h"
#include <errno.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
int xlocaltime(const time_t *timep, struct tm *result) {
// Should be called before localtime_r() according to POSIX.1-2004
tzset();
if (localtime_r(timep, result)) {
return 0;
} else {
return -1;
}
}
int xgmtime(const time_t *timep, struct tm *result) {
// Should be called before gmtime_r() according to POSIX.1-2004
tzset();
if (gmtime_r(timep, result)) {
return 0;
} else {
return -1;
}
}
int xmktime(struct tm *tm, time_t *timep) {
*timep = mktime(tm);
if (*timep == -1) {
int error = errno;
struct tm tmp;
if (xlocaltime(timep, &tmp) != 0) {
return -1;
}
if (tm->tm_year != tmp.tm_year || tm->tm_yday != tmp.tm_yday
|| tm->tm_hour != tmp.tm_hour || tm->tm_min != tmp.tm_min || tm->tm_sec != tmp.tm_sec) {
errno = error;
return -1;
}
}
return 0;
}
int xtimegm(struct tm *tm, time_t *timep) {
// Some man pages for timegm() recommend this as a portable approach
int ret = -1;
int error;
char *old_tz = getenv("TZ");
if (old_tz) {
old_tz = strdup(old_tz);
if (!old_tz) {
error = errno;
goto fail;
}
}
if (setenv("TZ", "UTC0", true) != 0) {
error = errno;
goto fail;
}
ret = xmktime(tm, timep);
error = errno;
if (old_tz) {
if (setenv("TZ", old_tz, true) != 0) {
ret = -1;
error = errno;
goto fail;
}
} else {
if (unsetenv("TZ") != 0) {
ret = -1;
error = errno;
goto fail;
}
}
tzset();
fail:
free(old_tz);
errno = error;
return ret;
}
/** Parse some digits from a timestamp. */
static int parse_timestamp_part(const char **str, size_t n, int *result) {
char buf[n + 1];
for (size_t i = 0; i < n; ++i, ++*str) {
char c = **str;
if (c < '0' || c > '9') {
return -1;
}
buf[i] = c;
}
buf[n] = '\0';
*result = atoi(buf);
return 0;
}
int parse_timestamp(const char *str, struct timespec *result) {
struct tm tm = {
.tm_isdst = -1,
};
int tz_hour = 0;
int tz_min = 0;
bool tz_negative = false;
bool local = true;
// YYYY
if (parse_timestamp_part(&str, 4, &tm.tm_year) != 0) {
goto invalid;
}
tm.tm_year -= 1900;
// MM
if (*str == '-') {
++str;
}
if (parse_timestamp_part(&str, 2, &tm.tm_mon) != 0) {
goto invalid;
}
tm.tm_mon -= 1;
// DD
if (*str == '-') {
++str;
}
if (parse_timestamp_part(&str, 2, &tm.tm_mday) != 0) {
goto invalid;
}
if (!*str) {
goto end;
} else if (*str == 'T') {
++str;
}
// hh
if (parse_timestamp_part(&str, 2, &tm.tm_hour) != 0) {
goto invalid;
}
// mm
if (!*str) {
goto end;
} else if (*str == ':') {
++str;
}
if (parse_timestamp_part(&str, 2, &tm.tm_min) != 0) {
goto invalid;
}
// ss
if (!*str) {
goto end;
} else if (*str == ':') {
++str;
}
if (parse_timestamp_part(&str, 2, &tm.tm_sec) != 0) {
goto invalid;
}
if (!*str) {
goto end;
} else if (*str == 'Z') {
local = false;
++str;
} else if (*str == '+' || *str == '-') {
local = false;
tz_negative = *str == '-';
++str;
// hh
if (parse_timestamp_part(&str, 2, &tz_hour) != 0) {
goto invalid;
}
// mm
if (!*str) {
goto end;
} else if (*str == ':') {
++str;
}
if (parse_timestamp_part(&str, 2, &tz_min) != 0) {
goto invalid;
}
} else {
goto invalid;
}
if (*str) {
goto invalid;
}
end:
if (local) {
if (xmktime(&tm, &result->tv_sec) != 0) {
goto error;
}
} else {
if (xtimegm(&tm, &result->tv_sec) != 0) {
goto error;
}
int offset = 60*tz_hour + tz_min;
if (tz_negative) {
result->tv_sec -= offset;
} else {
result->tv_sec += offset;
}
}
result->tv_nsec = 0;
return 0;
invalid:
errno = EINVAL;
error:
return -1;
}
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