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