producer.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;
    char buffer[BUFSIZ];
    int shmid;
   
    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 failed\n");
        exit(EXIT_FAILURE);
    }
    printf("Memory attched at %X\n",(int)shared_memory);
    
    shared_stuff = (struct shared_use_st *)shared_memory;
    while(running) {
        while(shared_stuff->written_by_you ==1) {
            sleep(1);
            printf("waiting for client...\n");
        }
        printf("Enter some text: ");
        fgets(buffer,BUFSIZ,stdin);
        
        strncpy(shared_stuff->some_text,buffer,TEXT_SZ);
        shared_stuff->written_by_you=1;
        if(strncpy(buffer,"end",3)==0) {
              running=0;
        }
    }
    if(shmdt(shared_memory)==-1) {
        fprintf(stderr,"shmdt failure\n");
        exit(EXIT_FAILURE);
    }
    exit(EXIT_SUCCESS);
}