//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 = 5120;    char buf[buflen];    int i = 0;    memset(buf, 0, 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[128] = {0};    snprintf(logpath,sizeof(logpath),"/var/log/");    if(access(logpath,0)!=0)    {        char cmdstr[256] = {0};        sprintf(cmdstr,"mkdir -p %s",logpath);        system(cmdstr);    }    char fname[256];    char longtime[200];    time_t t;    memset(fname,0,sizeof(fname));    time(&t);    struct tm local = {0};    localtime_r(&t, &local);    sprintf(longtime,"%04d-%02d-%02d %02d:%02d:%02d", local.tm_year+1900,            local.tm_mon+1, local.tm_mday, local.tm_hour, local.tm_min, local.tm_sec);    sprintf(fname,"%s/%s", logpath, PROCESSNAME);    for(i= 0; i < 3; i++)    {        logfile = fopen(fname, "ab");        if(logfile)            break;        sleep(1);    }    if(logfile)    {        // 判断文件大小        if (ftell(logfile) < 5*1024*1024)   // 5M        {            //日期时间            const char* pTemp = longtime;            fwrite(pTemp, 1, strlen(pTemp), logfile);            fwrite(" ", 1, 1, logfile);            //内容            fwrite(buf, 1, strlen(buf), logfile);            fwrite(" \r\n", 1, 3, logfile);            fclose(logfile);        }        else        {            fclose(logfile);            remove(fname);        }    }}