添加看门狗程序

在嵌入式系统中，为了防止主应用程序因为不明的原因无故死掉或者程序跑飞，需要加入一个看门狗程序保证系统能够重启（reboot）。

//Linux watch dog test


//http://www.cnblogs.com/zengjfgit/p/5396041.html

/***********************************************************************
 *                  Linux Watchdog Test Program
 * 说明：
 *     由于之前的reset一直没有得到解决，所以这个Watchdog功能一直没有处理，
 * 现在问题解决了，于是需要加入这个测试程序。
 *
 **********************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/types.h>
#include <linux/watchdog.h>

#define  ZERO 0
#define  SUCCESS 0
#define  FAIL   1

#define     DDBUG                                 1
#undef      DDBUG
#if DDBUG
    #define DEBUG_PRINT(fmt, args...) fprintf(stdout, fmt, ##args)
#else
    #define DEBUG_PRINT(fmt, args...)
#endif


// watchdog 只要一直打开设备节点不喂，然后等待设定的时间结束引发reset。
int main(void)
{

    int fd_watchdog;
    fd_watchdog = open("/dev/watchdog", O_WRONLY); //open device
    if (fd_watchdog == -1) {
        fprintf(stderr, "Watchdog device not enabled.
");
        fflush(stderr);
        exit(-1);
    }

    int timeout = 60;  //60seconds
    const int wdt_enable = WDIOS_ENABLECARD;
    ioctl(fd_watchdog, WDIOC_SETOPTIONS, (void*)&wdt_enable);  //open watchdog   
    ioctl(fd_watchdog, WDIOC_SETTIMEOUT, &timeout);
    DEBUG_PRINT("The timeout was set to %d seconds
", timeout);
    


    while(1){
        
        {
            ioctl(fd_watchdog, WDIOC_GETTIMEOUT, &timeout);
            printf("The timeout was is %d seconds.
", timeout);
        }
        
        int timeleft = timeout - 10;
        //while((timeleft--) >= 0) {
        //    //DEBUG_PRINT("The timeout left %d seconds
", timeleft);
        //    sleep(1);
        //}
        
        mysleep(timeleft);
        
        if( SUCCESS == checkProcessExist("miniTerminal")) // Only when miniTerminal is running, will we feed the watchdog
        {     
            ////feed the watchdog
            if(fd_watchdog >= 0) {
                feeddog(fd_watchdog);
            }
        }
        
        sleep(10);
    }
}

void mysleep(int timelength){
    while((timelength--) >= 0) {
        //DEBUG_PRINT("The timeout left %d seconds
", timeleft);
        sleep(1);
    }
    
    return;
}


void feeddog(int fd_watchdog)
{
    //ioctl(fd_watchdog, WDIOC_KEEPALIVE, 0);
    static unsigned char food = 0;
    ssize_t eaten = write(fd_watchdog, &food, 1);
    if(eaten != 1) {
        DEBUG_PRINT("
!!! FAILED feeding watchdog
");
        //syslog(LOG_WARNING, "FAILED feeding watchdog");
    }  

     fsync(fd_watchdog);  // if you don't fsync fd_watchdog, then the write won't function normally.
     return;
}

int checkProcessExist(char *name)
{
    //char *Name = "miniTerminal";
    FILE *pstr;
    char cmd[100];
    char number[10];
    
    int ret = SUCCESS;
    
    memset(cmd, 0 , sizeof(cmd));
    sprintf(cmd,"ps | grep %s | grep -v grep | wc -l",name);
    pstr=popen(cmd,"r");

    fgets(number,9, pstr);
    DEBUG_PRINT("number is %d
",atoi(number));
    
    if( ZERO == atoi(number))
    {
        DEBUG_PRINT("process - %s not exist!
",name);
        ret = FAIL;
    }
    else
    {
        DEBUG_PRINT("process - %s exist!
",name);
        ret = SUCCESS;
    }
    
    pclose(pstr);
    return ret;
    
}

设置看门狗的超时时间为80秒，如果在80秒以内检测到程序存在，则喂狗；否则，不喂狗，等待系统reboot。测试，OK。