59 lines
1.2 KiB
C
59 lines
1.2 KiB
C
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// System V message queues: reads from a message queue, sends back
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// response
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//
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// Based on: http://beej.us/guide/bgipc/output/html/multipage/mq.html
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#include <stdio.h>
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#include <stdlib.h>
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#include <errno.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 <string.h>
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struct my_msgbuf {
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long mtype;
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char mtext[200];
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};
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int main(void){
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// Get a unique IPC key based on a file name
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key_t key = ftok("kirk.c", 'B');
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if(key == -1){
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perror("ftok");
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exit(1);
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}
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// Connect to message queue based on the key provided
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int msqid = msgget(key, 0644 | IPC_CREAT);
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if(msqid == -1) {
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perror("msgget");
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exit(1);
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}
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printf("spock: ready to receive messages, captain.\n");
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// Spock never quits: forever wait for messages in the queue
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struct my_msgbuf buf;
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for(;;) {
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int received = msgrcv(msqid, &buf, sizeof buf.mtext, 0, 0);
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if (received == -1) {
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perror("msgrcv");
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exit(1);
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}
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printf("spock: \"%s\"\n", buf.mtext);
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// Respond to the message
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strcpy(buf.mtext,"Acknowledged, Captain.");
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int len = strlen(buf.mtext);
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int sent = msgsnd(msqid, &buf, len+1, 0);
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if (sent == -1){
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perror("msgsnd");
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}
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}
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return 0;
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}
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