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/*
* Common RTC functions
*
* Licensed under GPLv2, see file LICENSE in this source tree.
*/
#include "libbb.h"
#include "rtc_.h"
int FAST_FUNC rtc_adjtime_is_utc(void)
{
int utc = 0;
FILE *f = fopen_for_read(ADJTIME_PATH);
if (f) {
char buffer[128];
while (fgets(buffer, sizeof(buffer), f)) {
if (is_prefixed_with(buffer, "UTC")) {
utc = 1;
break;
}
}
fclose(f);
}
return utc;
}
/* rtc opens are exclusive.
* Try to run two "hwclock -w" at the same time to see it.
* Users wouldn't expect that to fail merely because /dev/rtc
* was momentarily busy, let's try a bit harder on errno == EBUSY.
*/
static int open_loop_on_busy(const char *name, int flags)
{
int rtc;
/*
* Tested with two parallel "hwclock -w" loops.
* With try = 10, no failures with 2x1000000 loop iterations.
*/
int try = 1000 / 20;
again:
errno = 0;
rtc = open(name, flags);
if (errno == EBUSY) {
usleep(20 * 1000);
if (--try != 0)
goto again;
/* EBUSY. Last try, exit on error instead of returning -1 */
return xopen(name, flags);
}
return rtc;
}
/* Never fails */
int FAST_FUNC rtc_xopen(const char **default_rtc, int flags)
{
int rtc;
const char *name =
"/dev/rtc""\0"
"/dev/rtc0""\0"
"/dev/misc/rtc""\0";
if (!*default_rtc)
goto try_name;
name = ""; /*else: we have rtc name, don't try other names */
for (;;) {
rtc = open_loop_on_busy(*default_rtc, flags);
if (rtc >= 0)
return rtc;
if (!name[0])
return xopen(*default_rtc, flags);
try_name:
*default_rtc = name;
name += strlen(name) + 1;
}
}
void FAST_FUNC rtc_read_tm(struct tm *ptm, int fd)
{
memset(ptm, 0, sizeof(*ptm));
xioctl(fd, RTC_RD_TIME, ptm);
ptm->tm_isdst = -1; /* "not known" */
}
time_t FAST_FUNC rtc_tm2time(struct tm *ptm, int utc)
{
char *oldtz = oldtz; /* for compiler */
time_t t;
if (utc) {
oldtz = getenv("TZ");
putenv((char*)"TZ=UTC0");
tzset();
}
t = mktime(ptm);
if (utc) {
unsetenv("TZ");
if (oldtz)
putenv(oldtz - 3);
tzset();
}
return t;
}
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