msgtool.c

操作系统Interprocess Communication（IPC）实验源码。 在Unix的内核环境中

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>

#define MAX_SEND_SIZE 80

struct mymsgbuf {
  long mtype;
  char mtext[MAX_SEND_SIZE];
};

void send_message(int qid,struct mymsgbuf *qbuf,long type,char *text);
void read_message(int qid,struct mymsgbuf *qbuf,long type);
void remove_queue(int qid);
void change_queue_mode(int qid,char *mode);
void usage(void);

int main(int argc,char *argv[])
{
  key_t key;
  int msgqueue_id;
  struct mymsgbuf qbuf;
  
  if (argc==1)
    usage();

  /* Create unique key via call to ftok() */
  key=ftok(".",'m');

  if ((msgqueue_id=msgget(key,IPC_CREAT|0666))==-1) {
    perror("msgget");
    exit(1);
  }
  switch (tolower(argv[1][0])) {
  case 's':
    send_message(msgqueue_id,&qbuf,
		 atol(argv[2]),argv[3]);
    break;
  case 'r':
    read_message(msgqueue_id,&qbuf,atol(argv[2]));
    break;
  case 'd':
    remove_queue(msgqueue_id);
    break;
  case 'm':
    change_queue_mode(msgqueue_id,argv[2]);
    break;
  }
  return 0;
}

void send_message(int qid,struct mymsgbuf *qbuf,long type, char *text)
{
  printf("Sending a message...\n");
  qbuf->mtype=type;
  strcpy(qbuf->mtext,text);
  if (msgsnd(qid,(struct msgbuf*)qbuf,
	     strlen(qbuf->mtext)+1,0)==-1) {
    perror("msgsnd");
    exit(1);
  }
}

void read_message(int qid,struct mymsgbuf *qbuf, long type)
{
  printf("Reading a message...\n");
  qbuf->mtype=type;
  msgrcv(qid,(struct msgbuf*)qbuf,MAX_SEND_SIZE,type,0);
  printf("Type: %ld Text: %s\n",qbuf->mtype,qbuf->mtext);
}

void remove_queue(int qid)
{
  msgctl(qid,IPC_RMID,0);
}

void change_queue_mode(int qid,char *mode)
{
  struct msqid_ds myqueue_ds;
  msgctl(qid,IPC_STAT,&myqueue_ds);
  sscanf(mode,"%ho",&myqueue_ds.msg_perm.mode);
  msgctl(qid,IPC_SET,&myqueue_ds);
}

void usage()
{
  fprintf(stderr,"msgtool-A utility for tinkering with msg queues\n");
  fprintf(stderr,"\nUSAGE:msgtool (s)end<type><messagetext>\n");
  fprintf(stderr,"                (r)ecv<type>\n");
  fprintf(stderr,"                (d)elete\n");
  fprintf(stderr,"                (m)ode<octal mode>\n");
  exit(1);
}