システムプログラミング：プロセス間通信(メッセージキュー利用)

[msend.c]

#include <stdio.h>

#include <stdlib.h>

#include <="" span="">ipc.h>

#include <="" span="">types.h>

#include <unistd.h>

int main(){

  struct msgbuf{

  long mtype;

  char mtext [256];

  };

  char line [256];

  int msqid;

  key_t msgkey;

  struct msgbuf msgdata, *p;

  p=&msgdata;

  printf (“Enter message: “);

  fflush (stdout);

  fgets (line, sizeof (line), stdin);

  if (sscanf (line, “%[^＼n]”, p->mtext) >0){

  //　プロセスIDをmtypeに入れる

  p->mtype=getpid ();

  msgkey=ftok (“mrecv”, ‘a’);

  //　メッセージキュー識別子を得る

  msqid=msgget (msgkey, IPC_CREAT | 0666);

  //　メッセージを送信する

  msgsnd (msqid, p, sizeof (p->mtext), 0);

  }

  return EXIT_SUCCESS;

}

[mrecv.c]

#include <stdio.h>

#include <stdlib.h>

#include <="" span="">ipc.h>

#include <="" span="">msg.h>

#include <="" span="">types.h>

int main(){

  struct msgbuf{

  long mtype;

  char mtext [256];

  };

  int msqid;

  key_t msgkey;

  struct msgbuf msgdata, *p;

  p=&msgdata;

  msgkey=ftok (“mrecv”, ‘a’);

  //　メッセージキュー識別子を得る

  msqid=msgget (msgkey, IPC_CREAT | 0666);

  while (1){ //無限ループ

  //　メッセージを受信する

  msgrcv (msqid, p, sizeof (p->mtext), 0, 0);

  printf (“message received from %ld＼n%s＼n” ,p->mtype, p->mtext);

  }

  return EXIT_SUCCESS;

}

atmark@atde3:~/Desktop/work$ gcc -o mrecv mrecv.c
atmark@atde3:~/Desktop/work$ gcc -o msend msend.c
atmark@atde3:~/Desktop/work$ ./msend
Enter message: Hello
atmark@atde3:~/Desktop/work$ ./msend
Enter message: Good
atmark@atde3:~/Desktop/work$ ./mrecv
message received from 10658
Hello
message received from 10659
Good