buffers.c

unix网络编程卷1：套接口API的全书源码

/*
 * Copyright (c) 1993 W. Richard Stevens.  All rights reserved.
 * Permission to use or modify this software and its documentation only for
 * educational purposes and without fee is hereby granted, provided that
 * the above copyright notice appear in all copies.  The author makes no
 * representations about the suitability of this software for any purpose.
 * It is provided "as is" without express or implied warranty.
 */

#include	"sock.h"

void
buffers(int sockfd)
{
	int			n;
	socklen_t	optlen;

		/* Allocate the read and write buffers. */

	if (rbuf == NULL) {
		if ( (rbuf = malloc(readlen)) == NULL)
			err_sys("malloc error for read buffer");
	}

	if (wbuf == NULL) {
		if ( (wbuf = malloc(writelen)) == NULL)
			err_sys("malloc error for write buffer");
	}

		/* Set the socket send and receive buffer sizes (if specified).
		   The receive buffer size is tied to TCP's advertised window. */

	if (rcvbuflen) {
		if (setsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &rcvbuflen,
													sizeof(rcvbuflen)) < 0)
			err_sys("SO_RCVBUF setsockopt error");
	
		optlen = sizeof(n);
		if (getsockopt(sockfd, SOL_SOCKET, SO_RCVBUF, &n, &optlen) < 0)
			err_sys("SO_RCVBUF getsockopt error");
		if (n != rcvbuflen)
			err_quit("rcvbuflen = %d, SO_RCVBUF = %d", rcvbuflen, n);
		if (verbose)
			fprintf(stderr, "SO_RCVBUF = %d\n", n);
	}

	if (sndbuflen) {
		if (setsockopt(sockfd, SOL_SOCKET, SO_SNDBUF, &sndbuflen,
													sizeof(sndbuflen)) < 0)
			err_sys("SO_SNDBUF setsockopt error");
	
		optlen = sizeof(n);
		if (getsockopt(sockfd, SOL_SOCKET, SO_SNDBUF, &n, &optlen) < 0)
			err_sys("SO_SNDBUF getsockopt error");
		if (n != sndbuflen)
			err_quit("sndbuflen = %d, SO_SNDBUF = %d", sndbuflen, n);
		if (verbose)
			fprintf(stderr, "SO_SNDBUF = %d\n", n);
	}
}