CODEWITHSUNDEEP
cstringsocketsclientreadline
matthieu
matthieu

Reputation: 109

reading all lines from client in C

I want to read and process all lines from the clients but it seems like only one line is being read at a time. I thought having a loop while there is read data would read it all but it doesn't seem to be the case. If the read is incomplete, I will continue it off at that index in the next step.

I have something like this:

if (select(maxfd + 1, &fdlist, NULL, NULL, NULL) < 0) {
    perror("select");
} else {
    if (FD_ISSET(listenfd, &fdlist)) {
        newclientconnection();
    }

    // see which clients have activity
    for (p = head; p; p = p->next) {
        if (FD_ISSET(p->fd, &fdlist)) {
            // want to read all lines from client
            while ((n = read(p->fd, p->buf + lastindex, MAX-p->lastindex) > 0) {
                p->lastindex += n;          
            }
            if (n==0) {
                removeclient(p);
            } 

            // want to process all the lines
            process(p->buf);
    } 
}

Upvotes: 0

Views: 104

Answers (1)

MeNa
MeNa

Reputation: 1487

You have blocking in this line:

while ((n = read(p->fd, p->buf + lastindex, MAX-p->lastindex) > 0))

On the last iteration, the while cond. waits for input from read. but the input already read. so, waiting for new input.

If you assume that you gona get data bigger than buffer (therefore you put read into while condition), you need to define timeout (select etc) for read OR define special symbol ("\r\n\r\n" for example) to determine "this is end of the data". Otherwise, the while loop will wait forever for more data.

Upvotes: 1

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