92 lines
2.0 KiB
C
92 lines
2.0 KiB
C
/*
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* msg1 This program tests synchronization of sending and receiving
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* messages. It forks into a parent, which sends 10 messages,
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* and a child, which reads 10 and sees if the text is correct.
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* The child may sleep temporarily if it gets ahead of the parent,
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* but the should always catch up eventually.
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*/
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#include <stdio.h>
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#include <unistd.h>
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#include <malloc.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/ipc.h>
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#include <sys/msg.h>
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#include <sys/wait.h>
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#define nextarg {argc--; argv++;}
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int
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main(int argc, char **argv)
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{
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register int i;
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int msqid;
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struct msgbuf *sendmsgp;
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struct msgbuf *recvmsgp;
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char message[30];
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size_t messagelen;
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pid_t pid;
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int wval;
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sprintf(message, "Message %02d", 0);
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messagelen = strlen(message)+1;
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if ((sendmsgp = (struct msgbuf *)malloc(sizeof(struct msgbuf)+messagelen)) == NULL) {
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fprintf(stderr, "malloc failed\n");
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exit(1);
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}
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if ((recvmsgp = (struct msgbuf *)malloc(sizeof(struct msgbuf)+messagelen)) == NULL) {
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fprintf(stderr, "malloc failed\n");
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exit(1);
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}
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if ((msqid = msgget(IPC_PRIVATE, 0777)) < 0) {
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perror("msgget");
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exit(1);
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}
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if ((pid = fork()) == -1) {
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perror("fork");
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if (msgctl(msqid, IPC_RMID, 0) < 0) {
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perror("msgctl");
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}
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exit(1);
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}
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if (pid) { /* PARENT */
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sleep(2);
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sendmsgp->mtype = 1;
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for (i = 10; i--; ) {
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sprintf(message, "Message %02d", i);
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strcpy(sendmsgp->mtext, message);
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if (msgsnd(msqid, sendmsgp, messagelen, 0) < 0) {
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perror("msgsnd");
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}
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}
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if ((wval = wait(0)) != pid) {
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if (wval == -1) {
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perror("wait");
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} else {
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fprintf(stderr, "wait returned bogus pid\n");
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}
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exit(1);
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}
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exit(0);
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} else { /* CHILD */
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for (i = 10; i--; ) {
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sprintf(message, "Message %02d", i);
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if (msgrcv(msqid, recvmsgp, messagelen, 0, 0) < 0) {
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perror("msgrcv");
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}
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if (strcmp(recvmsgp->mtext, message) != 0) {
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fprintf(stderr, "FAIL\n");
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}
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}
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if (msgctl(msqid, IPC_RMID, 0) < 0) {
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perror("msgctl");
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exit(1);
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}
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}
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return(0);
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}
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