ptg10805159824 Communicating with a Network Printer Chapter 21
352 /*
353 * Accept a print job from a client.
354 *
355 * LOCKING: none.
356 */
357 void *
358 client_thread(void *arg)
359 {
360 int n, fd, sockfd, nr, nw, first;
361 int32_t jobid;
362 pthread_t tid;
363 struct printreq req;
364 struct printresp res;
365 char name[FILENMSZ];
366 char buf[IOBUFSZ];
367 tid=pthread_self();
368 pthread_cleanup_push(client_cleanup, (void *)((long)tid));
369 sockfd=(long)arg;
370 add_worker(tid, sockfd);
371 /*
372 * Read the request header.
373 */
374 if ((n = treadn(sockfd, &req, sizeof(struct printreq), 10)) !=
375 sizeof(struct printreq)) {
376 res.jobid=0;
377 if (n < 0)
378 res.retcode =htonl(errno);
379 else
380 res.retcode =htonl(EIO);
381 strncpy(res.msg, strerror(res.retcode), MSGLEN_MAX);
382 writen(sockfd, &res, sizeof(struct printresp));
383 pthread_exit((void *)1);
384 }[352 – 370] Theclient_threadis spawned from themainthread when a connect
request is accepted. Its job is to receive the file to be printed from the client
printcommand. Wecreate a separate thread for each client print request.
The first thing we do is install a thread cleanup handler (see Section 11.5 for
adiscussion of thread cleanup handlers). The cleanup handler is
client_cleanup,which we will see later.Ittakes a single argument: our
thread ID. Then we calladd_workerto create aworker_threadstructure
and add it to the list of active client threads.
[371 – 384] At this point, we aredone with the thread’s initialization tasks, so we read
the request header from the client. If the client sends less data than we
expect or we encounter an error, we respond with a message indicating the
reason for the error and callpthread_exitto terminate the thread.