Network Programming Question. I need to call sysconf to determine the maximum number of descriptors and allocate the client array accordingly.

/* include fig01 */ #include "unp.h" #include /* for OPEN_MAX */ #include

int main(int argc, char **argv) { int i, maxi, listenfd, connfd, sockfd; int nready; ssize_t n; char buf[MAXLINE]; socklen_t clilen; struct pollfd client[OPEN_MAX]; struct sockaddr_in cliaddr, servaddr;

listenfd = Socket(AF_INET, SOCK_STREAM, 0);

bzero(&servaddr, sizeof(servaddr)); servaddr.sin_family = AF_INET; servaddr.sin_addr.s_addr = htonl(INADDR_ANY); servaddr.sin_port = htons(SERV_PORT);

Bind(listenfd, (SA *) &servaddr, sizeof(servaddr));

Listen(listenfd, LISTENQ);

client[0].fd = listenfd; client[0].events = POLLRDNORM; for (i = 1; i < OPEN_MAX; i++) client[i].fd = -1; /* -1 indicates available entry */ maxi = 0; /* max index into client[] array */ /* end fig01 */

/* include fig02 */ for ( ; ; ) { nready = Poll(client, maxi+1, INFTIM);

if (client[0].revents & POLLRDNORM) { /* new client connection */ clilen = sizeof(cliaddr); connfd = Accept(listenfd, (SA *) &cliaddr, &clilen); #ifdef NOTDEF printf("new client: %s ", Sock_ntop((SA *) &cliaddr, clilen)); #endif

for (i = 1; i < OPEN_MAX; i++) if (client[i].fd < 0) { client[i].fd = connfd; /* save descriptor */ break; } if (i == OPEN_MAX) err_quit("too many clients");

client[i].events = POLLRDNORM; if (i > maxi) maxi = i; /* max index in client[] array */

if (--nready <= 0) continue; /* no more readable descriptors */ }

for (i = 1; i <= maxi; i++) { /* check all clients for data */ if ( (sockfd = client[i].fd) < 0) continue; if (client[i].revents & (POLLRDNORM | POLLERR)) { if ( (n = read(sockfd, buf, MAXLINE)) < 0) { if (errno == ECONNRESET) { /*4connection reset by client */ #ifdef NOTDEF printf("client[%d] aborted connection ", i); #endif Close(sockfd); client[i].fd = -1; } else err_sys("read error"); } else if (n == 0) { /*4connection closed by client */ #ifdef NOTDEF printf("client[%d] closed connection ", i); #endif Close(sockfd); client[i].fd = -1; } else Writen(sockfd, buf, n);

if (--nready <= 0) break; /* no more readable descriptors */ } } } } /* end fig02 */