97 lines
3.5 KiB
C
97 lines
3.5 KiB
C
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/* This file is part of the sample code and exercises
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* used by the class "Advanced Programming in the UNIX
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* Environment" taught by Jan Schaumann
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* <jschauma@netmeister.org> at Stevens Institute of
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* Technology.
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*
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* https://stevens.netmeister.org/631/
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*/
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/* $NetBSD: socketpair.c,v 1.3 2003/08/07 10:30:50 agc Exp $
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*
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* Copyright (c) 1986, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR
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* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
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* DAMAGE.
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*
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* @(#)socketpair.c 8.1 (Berkeley) 6/8/93
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*/
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <sys/wait.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#define DATA1 "In Xanadu, did Kubla Khan . . ."
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#define DATA2 "A stately pleasure dome decree . . ."
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/*
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* This program creates a pair of connected sockets then forks and
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* communicates over them. This is very similar to communication with pipes,
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* however, socketpairs are two-way communications objects. Therefore I can
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* send messages in both directions.
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*/
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int main()
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{
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int sockets[2], child;
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char buf[BUFSIZ];
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if (socketpair(AF_UNIX, SOCK_STREAM, 0, sockets) < 0) {
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perror("opening stream socket pair");
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exit(1);
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}
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/* Note: Execution order of parent/child is not guaranteed! Hence,
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* order of data being sent/read is entirely undefined. Do not
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* rely on any order, even if you repeatedly observe it to follow
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* what you perceive as a pattern. */
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if ((child = fork()) == -1)
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perror("fork");
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else if (child) {
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close(sockets[0]);
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if (read(sockets[1], buf, BUFSIZ) < 0)
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perror("reading stream message");
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printf("Parent (%d) --> reading: %s\n", getpid(), buf);
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printf("Parent (%d) --> sending: %s\n", getpid(), DATA1);
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if (write(sockets[1], DATA1, sizeof(DATA1)) < 0)
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perror("writing stream message");
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close(sockets[1]);
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} else {
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close(sockets[1]);
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if (read(sockets[0], buf, BUFSIZ) < 0)
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perror("reading stream message");
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printf("Child (%d) --> reading: %s\n", getpid(), buf);
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printf("Child (%d) --> sending: %s\n", getpid(), DATA2);
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if (write(sockets[0], DATA2, sizeof(DATA2)) < 0)
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perror("writing stream message");
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close(sockets[0]);
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}
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return 0;
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}
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