嵌入式Linux 设置时间和日期 API ，它是busybox要提取的源代码。

Linux设置时间和日期的步骤：

1. 设置系统时间和日期；

2. 该系统的时间和日期，同步到硬件。

#include

#include

#include

#include

#include

#include

#include

#include

int SetSysDateAndTime(const char *time_str);

void SetHWClockFromSysClock(int utc);

static int rtc_xopen(const char **default_rtc, int flags);

static void write_rtc(time_t t, int utc);

static const char *rtcname;

int main(void)

{

const char time_str[] = "1989-11-22 11:22:33";

SetSysDateAndTime(time_str);

SetHWClockFromSysClock(0);

system("reboot");

return 0;

}

int SetSysDateAndTime(const char *time_str)

{

struct tm time_tm;

struct timeval time_tv;

time_t timep;

int ret;

if(time_str == NULL)

{

fprintf(stderr, "time string args invalid!\n");

return -1;

}

sscanf(time_str, "%d-%d-%d %d:%d:%d", &time_tm.tm_year, &time_tm.tm_mon, &time_tm.tm_mday, &time_tm.tm_hour, &time_tm.tm_min, &time_tm.tm_sec);

time_tm.tm_year -= 1900;

time_tm.tm_mon -= 1;

time_tm.tm_wday = 0;

time_tm.tm_yday = 0;

time_tm.tm_isdst= 0;

timep = mktime(&time_tm);

time_tv.tv_sec = timep;

time_tv.tv_usec = 0;

ret = settimeofday(&time_tv, NULL);

if(ret != 0)

{

fprintf(stderr, "settimeofday failed\n");

return -2;

}

return 0;

}

void SetHWClockFromSysClock(int utc)

{

struct timeval tv;

gettimeofday(&tv, NULL);

//if (gettimeofday(&tv, NULL))

//bb_perror_msg_and_die("gettimeofday() failed");

write_rtc(tv.tv_sec, utc);

}

static int rtc_xopen(const char **default_rtc, int flags)

{

int rtc;

if (!*default_rtc) {

*default_rtc = "/dev/rtc";

rtc = open(*default_rtc, flags);

if (rtc >= 0)

return rtc;

*default_rtc = "/dev/rtc0";

rtc = open(*default_rtc, flags);

if (rtc >= 0)

return rtc;

*default_rtc = "/dev/misc/rtc";

}

return open(*default_rtc, flags);

}

static void write_rtc(time_t t, int utc)

{

#define RTC_SET_TIME_IOW('p', 0x0a, struct rtc_time) /* Set RTC time */

struct tm tm;

int rtc = rtc_xopen(&rtcname, O_WRONLY);

tm = *(utc ?

gmtime(&t) : localtime(&t));

tm.tm_isdst = 0;

ioctl(rtc, RTC_SET_TIME, &tm);

close(rtc);

}