How to terminate read() when EOF is not encountered?

I am building a client/server model but using sockets, using named pipes, with mkfifo().

A client writes output into the name pipe, and I read the input in my server using:

while ((n = read(fd_in, &newChar, 1)) == 1) { /* ... */ }

I am reading one character at a time, until I encounter the two characters: <'CR'><'LF'>. I would like to make my code in such a way that if a client does not terminate with <'CR'><'LF'> after some time maybe, I can di开发者_运维问答scard it and proceed to another client, otherwise the next client will have to wait, maybe infinitely.

Is there a way please to terminate the execution of read()? If it has not returned in 2 seconds, I could say interrupt read and discard the previously read characters, and start reading again please?

Thank you for your help,

Jary

#include <stdbool.h>
#include <poll.h>

do {
    ssize_t ret;
    struct pollfd ps = {.fd = fd_in, .events = POLLIN}; 

    if (poll(&ps, 1, 2000) < 0)
        break; /* kick client */
    ret = read(in_fd, ...);
    if (ret != 1)
        break;
    /* process read data */
} while (true);

This checks for whether there is data to be read; if there is not within 2000 msec, do whatever it is you want (e.g. disconnect).

Try passing the O_NONBLOCK flag when you open the read-end of the FIFO. That should change the behavior so that read returns right away even if the number of requested characters is not in the pipe.

To handle multiple clients simultaneously, you should set the file descriptors non-blocking with fcntl(), and then use select() or poll() to block until input appears on at least one of them.