Mercurial > hg > toybox
view toys/pending/hwclock.c @ 1572:da1bf31ed322 draft
Tweak the "ignoring return value" fortify workaround for readlinkat.
We zero the buffer and if the link read fails that's left alone, so
it's ok for the symlink not to be there. Unfortunately, typecasting the
return value to (void) doesn't shut up gcc, and having an if(); with the
semicolon on the same line doesn't shut up llvm. (The semicolon on a new
line would, but C does not have significant whitespace and I'm not going
to humor llvm if it plans to start.)
So far, empty curly brackets consistently get the warning to shut up.
author | Rob Landley <rob@landley.net> |
---|---|
date | Mon, 24 Nov 2014 17:23:23 -0600 |
parents | f42dceed5071 |
children | 7e3372a47248 |
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/* hwclock.c - get and set the hwclock * * Copyright 2014 Bilal Qureshi <bilal.jmi@gmail.com> * * No Standard. * USE_HWCLOCK(NEWTOY(hwclock, ">0(fast)f(rtc):u(utc)l(localtime)t(systz)w(systohc)s(hctosys)r(show)[!ul][!rsw]", TOYFLAG_USR|TOYFLAG_BIN)) config HWCLOCK bool "hwclock" default n help usage: hwclock [-rswtluf] -f FILE Use specified device file instead of /dev/rtc (--show) -l Hardware clock uses localtime (--localtime) -r Show hardware clock time (--show) -s Set system time from hardware clock (--hctosys) -t Set the system time based on the current timezone (--systz) -u Hardware clock uses UTC (--utc) -w Set hardware clock from system time (--systohc) */ #define FOR_hwclock #include "toys.h" #include <linux/rtc.h> GLOBALS( char *fname; int utc; ) static int rtc_open(int flag) { if (!TT.fname) { int fd; if ((fd = open((TT.fname = "/dev/rtc"), flag)) != -1) return fd; else if ((fd = open((TT.fname = "/dev/rtc0"), flag)) != -1) return fd; else TT.fname = "/dev/misc/rtc"; } return xopen(TT.fname, flag); } static time_t get_rtc() { struct tm time; time_t tm; char *ptz_old = 0; int fd = rtc_open(O_RDONLY); xioctl(fd, RTC_RD_TIME, &time); close(fd); if (TT.utc) { ptz_old = getenv("TZ"); if (putenv((char*)"TZ=UTC0")) perror_exit("putenv"); tzset(); } if ((tm = mktime(&time)) < 0) error_exit("mktime failed"); if (TT.utc) { if (unsetenv("TZ") < 0) perror_exit("unsetenv"); if (ptz_old && putenv(ptz_old - 3)) perror_exit("putenv"); tzset(); } return tm; } static void set_sysclock_from_hwclock() { struct timezone tmzone; struct timeval tmval; tmzone.tz_minuteswest = timezone / 60 - 60 * daylight; tmzone.tz_dsttime = 0; tmval.tv_sec = get_rtc(); tmval.tv_usec = 0; if (settimeofday(&tmval, &tmzone) < 0) perror_exit("settimeofday"); } static void set_hwclock_from_sysclock() { struct timeval tmval; struct tm time; int fd = rtc_open(O_WRONLY); if (gettimeofday(&tmval, NULL) < 0) perror_exit("gettimeofday"); // converting a time value to broken-down UTC time if (TT.utc && !gmtime_r((time_t*)&tmval.tv_sec, &time)) error_exit("gmtime_r failed"); // converting a time value to a broken-down localtime else if (!(localtime_r((time_t*)&tmval.tv_sec, &time))) error_exit("localtime_r failed"); /* The value of tm_isdst will positive if daylight saving time is in effect, * zero if it is not and negative if the information is not available. * */ time.tm_isdst = 0; xioctl(fd, RTC_SET_TIME, &time); close(fd); } static void set_sysclock_timezone() { struct timezone tmzone; struct timeval tmval; struct tm *pb; if (gettimeofday(&tmval, NULL) < 0) perror_exit("gettimeofday"); if (!(pb = localtime(&tmval.tv_sec))) error_exit("localtime failed"); // extern long timezone => defined in header sys/time.h tmzone.tz_minuteswest = timezone / 60; if (pb->tm_isdst) tmzone.tz_minuteswest -= 60; tmzone.tz_dsttime = 0; // daylight saving time is not in effect if (gettimeofday(&tmval, NULL) < 0) perror_exit("gettimeofday"); if (!TT.utc) tmval.tv_sec += tmzone.tz_minuteswest * 60; if (settimeofday(&tmval, &tmzone) < 0) perror_exit("settimeofday"); } void hwclock_main() { // check for UTC if (!(toys.optflags & FLAG_u)) { FILE *fp = fopen("/etc/adjtime", "r"); if (fp) { char *line = NULL; size_t st; while (0 < getline(&line, &st, fp)) { if (!strncmp(line, "UTC", 3)) { TT.utc = 1; break; } free(line); } fclose(fp); } } else TT.utc = 1; if (toys.optflags & FLAG_w) set_hwclock_from_sysclock(); else if (toys.optflags & FLAG_s) set_sysclock_from_hwclock(); else if (toys.optflags & FLAG_t) set_sysclock_timezone(); else if ((toys.optflags & FLAG_r) || (toys.optflags & FLAG_l) || !*toys.optargs) { time_t tm = get_rtc(); char *s, *pctm = ctime(&tm); // ctime() is defined as equivalent to asctime(localtime(t)), // which is defined to overflow its buffer rather than return NULL. // if (!pctm) error_exit("can't happen"); if ((s = strrchr(pctm, '\n'))) *s = '\0'; // TODO: implement this. xprintf("%s 0.000000 seconds\n", pctm); } }