单线程读fifo写文件

int log_fifo2file(char *fifoname, char *filename, size_t size, int expire, int *exitflag)
{
        int             fd1, fd2;
        size_t  nread, nwrite, sum;
        char    file[PATH_MAX], filenew[PATH_MAX], tmp[16];
        char    buffer[65536];
        struct  pollfd  pfds[1];
        int     nfds;
        time_t  create, now;
        struct  stat st;
        struct  tm      tm;

        if(fifoname == NULL || filename == NULL)
                return EINVAL;
        /* open fifo */
        mkfifo(fifoname, 0644);
        if(stat(fifoname, &st) != 0)
                return errno;
        if(!S_ISFIFO(st.st_mode))
                return -1;
        if((fd1 = open(fifoname, O_RDWR|O_NONBLOCK, 0)) < 0)
                return errno;
        pfds[0].fd = fd1;
        pfds[0].events = POLLIN;
        /* open file */
        snprintf(file, sizeof(file), "%s.tmp", filename);
write:
        if((fd2 = open(file, O_WRONLY|O_NONBLOCK|O_CREAT, 0644)) < 0)
                return errno;
        create = time(NULL);
        sum = 0;
        /* read fifo, write file */
        while(!*exitflag){
                nfds = poll(pfds, 1, 1000);
                if(nfds <= 0)
                        goto check;
                nread = read(fd1, buffer, sizeof(buffer));
                if(nread < 0) continue;
                if(nread == 0) break;
                nwrite = write(fd2, buffer, nread);
                if(nwrite < 0) continue;
                sum += nwrite;
check:
                now = time(NULL);
                if((size > 0 && sum > size) || (expire > 0 && now > create + expire)){
                        close(fd2);
                        localtime_r(&now, &tm);
                        sprintf(tmp, "%04d%02d%02d%02d%02d%02d", tm.tm_year+1900, tm.tm_mon+1,tm.tm_mday, tm.tm_hour, tm.tm_min, tm .tm_sec);
                        snprintf(filenew, sizeof(filenew), "%s-%s.log", filename, tmp);
                        rename(file, filenew);
                        goto write;
                }
        }
        close(fd1);
        close(fd2);
        now = time(NULL);
        localtime_r(&now, &tm);
        sprintf(tmp, "%04d%02d%02d%02d%02d%02d", tm.tm_year+1900, tm.tm_mon+1,tm.tm_mday, tm.tm_hour, tm.tm_min, tm .tm_sec);
        snprintf(filenew, sizeof(filenew), "%s-%s.log", filename, tmp);
        rename(file, filenew);
        return 0;
}