consumer.c

信号量实现对生产者和消费者的共享内存的控制

#include<unistd.h>
#include<stdlib.h>
#include<stdio.h>
#include<string.h>

#include<sys/types.h>
#include<sys/ipc.h>
#include<sys/shm.h>

#include "shm_com.h"

int main()
{
    int running = 1;
    void *shared_memory=(void *)0;
    struct shared_use_st *shared_stuff;
    int shmid;
    srand((unsigned int)getpid());
    shmid = shmget((key_t)1234,sizeof(struct shared_use_st),0666|IPC_CREAT);
    if(shmid == -1) {
        fprintf(stderr,"shmget failed\n");
        exit(EXIT_FAILURE);
    }
    
    shared_memory = shmat(shmid,(void *)0,0);
    if(shared_memory == (void *)-1) {
        fprintf(stderr,"shmat failure\n");
        exit(EXIT_FAILURE);
    }
    printf("Memory attached at %X\n",(int)shared_memory);
   
    shared_stuff = (struct shared_use_st *)shared_memory;
    shared_stuff->written_by_you = 0;
    while(running) {
        if(shared_stuff->written_by_you)  {
            printf("You wrote:%s",shared_stuff->some_text);
            sleep(rand()%4);
            shared_stuff->written_by_you = 0;
            if(strncmp(shared_stuff->some_text,"end",3) ==0) {
                  running=0;
            }
        }
   }
   if(shmdt(shared_memory)==-1) {
       fprintf(stderr,"shmdt failed\n");
       exit(EXIT_FAILURE);
   }
   if(shmctl(shmid,IPC_RMID,0)==-1) {
      fprintf(stderr,"shmctl(IPC_RMID) failed\n");
      exit(EXIT_FAILURE);
   }
   exit(EXIT_SUCCESS);
}