[2725] | 1 | /*
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| 2 | * Common RTC functions
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| 3 | *
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| 4 | * Licensed under GPLv2, see file LICENSE in this source tree.
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| 5 | */
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| 6 |
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| 7 | #include "libbb.h"
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| 8 | #include "rtc_.h"
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| 9 |
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| 10 | #if ENABLE_FEATURE_HWCLOCK_ADJTIME_FHS
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| 11 | # define ADJTIME_PATH "/var/lib/hwclock/adjtime"
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| 12 | #else
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| 13 | # define ADJTIME_PATH "/etc/adjtime"
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| 14 | #endif
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| 15 |
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| 16 | int FAST_FUNC rtc_adjtime_is_utc(void)
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| 17 | {
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| 18 | int utc = 0;
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| 19 | FILE *f = fopen_for_read(ADJTIME_PATH);
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| 20 |
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| 21 | if (f) {
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| 22 | char buffer[128];
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| 23 |
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| 24 | while (fgets(buffer, sizeof(buffer), f)) {
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[3621] | 25 | if (is_prefixed_with(buffer, "UTC")) {
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[2725] | 26 | utc = 1;
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| 27 | break;
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| 28 | }
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| 29 | }
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| 30 | fclose(f);
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| 31 | }
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| 32 |
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| 33 | return utc;
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| 34 | }
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| 35 |
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[3621] | 36 | /* rtc opens are exclusive.
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| 37 | * Try to run two "hwclock -w" at the same time to see it.
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| 38 | * Users wouldn't expect that to fail merely because /dev/rtc
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| 39 | * was momentarily busy, let's try a bit harder on errno == EBUSY.
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| 40 | */
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| 41 | static int open_loop_on_busy(const char *name, int flags)
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| 42 | {
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| 43 | int rtc;
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| 44 | /*
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| 45 | * Tested with two parallel "hwclock -w" loops.
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| 46 | * With try = 10, no failures with 2x1000000 loop iterations.
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| 47 | */
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| 48 | int try = 1000 / 20;
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| 49 | again:
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| 50 | errno = 0;
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| 51 | rtc = open(name, flags);
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| 52 | if (errno == EBUSY) {
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| 53 | usleep(20 * 1000);
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| 54 | if (--try != 0)
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| 55 | goto again;
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| 56 | /* EBUSY. Last try, exit on error instead of returning -1 */
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| 57 | return xopen(name, flags);
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| 58 | }
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| 59 | return rtc;
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| 60 | }
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| 61 |
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| 62 | /* Never fails */
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[2725] | 63 | int FAST_FUNC rtc_xopen(const char **default_rtc, int flags)
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| 64 | {
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| 65 | int rtc;
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[3621] | 66 | const char *name =
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| 67 | "/dev/rtc""\0"
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| 68 | "/dev/rtc0""\0"
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| 69 | "/dev/misc/rtc""\0";
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[2725] | 70 |
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[3621] | 71 | if (!*default_rtc)
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| 72 | goto try_name;
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| 73 | name = ""; /*else: we have rtc name, don't try other names */
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| 74 |
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| 75 | for (;;) {
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| 76 | rtc = open_loop_on_busy(*default_rtc, flags);
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[2725] | 77 | if (rtc >= 0)
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| 78 | return rtc;
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[3621] | 79 | if (!name[0])
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| 80 | return xopen(*default_rtc, flags);
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| 81 | try_name:
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| 82 | *default_rtc = name;
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| 83 | name += strlen(name) + 1;
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[2725] | 84 | }
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| 85 | }
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| 86 |
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| 87 | void FAST_FUNC rtc_read_tm(struct tm *ptm, int fd)
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| 88 | {
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| 89 | memset(ptm, 0, sizeof(*ptm));
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| 90 | xioctl(fd, RTC_RD_TIME, ptm);
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| 91 | ptm->tm_isdst = -1; /* "not known" */
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| 92 | }
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| 93 |
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| 94 | time_t FAST_FUNC rtc_tm2time(struct tm *ptm, int utc)
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| 95 | {
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| 96 | char *oldtz = oldtz; /* for compiler */
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| 97 | time_t t;
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| 98 |
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| 99 | if (utc) {
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| 100 | oldtz = getenv("TZ");
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| 101 | putenv((char*)"TZ=UTC0");
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| 102 | tzset();
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| 103 | }
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| 104 |
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| 105 | t = mktime(ptm);
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| 106 |
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| 107 | if (utc) {
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| 108 | unsetenv("TZ");
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| 109 | if (oldtz)
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| 110 | putenv(oldtz - 3);
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| 111 | tzset();
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| 112 | }
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| 113 |
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| 114 | return t;
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| 115 | }
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