//宏定义日志文件名

#define PROCESSNAME  "log_filename"

//当日志文件大于5M时，会删除该文件，该接口使用方法 参照printf
void WriteLog(const char *fm, ...)

{

    int buflen = ;

    char buf[buflen];

    int i = ;

    memset(buf, , buflen);

    va_list args;

    va_start( args, fm );

    vsnprintf(buf, buflen, fm,args);

    va_end( args );

    printf("%s\n", buf);

    FILE* logfile=NULL;

    char logpath[] = {};

    snprintf(logpath,sizeof(logpath),"/var/log/");

    if(access(logpath,)!=)

    {

        char cmdstr[] = {};

        sprintf(cmdstr,"mkdir -p %s",logpath);

        system(cmdstr);

    }

    char fname[];

    char longtime[];

    time_t t;

    memset(fname,,sizeof(fname));

    time(&t);

    struct tm local = {};

    localtime_r(&t, &local);

    sprintf(longtime,"%04d-%02d-%02d %02d:%02d:%02d", local.tm_year+,

            local.tm_mon+, local.tm_mday, local.tm_hour, local.tm_min, local.tm_sec);

    sprintf(fname,"%s/%s", logpath, PROCESSNAME);

    for(i= ; i < ; i++)

    {

        logfile = fopen(fname, "ab");

        if(logfile)

            break;

        sleep();

    }

    if(logfile)

    {

        // 判断文件大小

        if (ftell(logfile) < **)   // 5M

        {

            //日期时间

            const char* pTemp = longtime;

            fwrite(pTemp, , strlen(pTemp), logfile);

            fwrite(" ", , , logfile);

            //内容

            fwrite(buf, , strlen(buf), logfile);

            fwrite(" \r\n", , , logfile);

            fclose(logfile);

        }

        else

        {

            fclose(logfile);

            remove(fname);

        }

    }

}