Programming

 
$ cat producer.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/stat.h>
#define MEM_SZ 4096
struct shared_use_st
{
        int written_by_you;
        char some_text[MEM_SZ];
};
int main()
{
int running = 1;
void *shared_memory = (void *)0;
struct shared_use_st *shared_stuff;
char buffer[MEM_SZ];
int shmid;
shmid = shmget((key_t)1234, MEM_SZ, 0666 | IPC_CREAT);
if(shmid == -1)
{
printf("shmget failed\n");
exit(EXIT_FAILURE);
}
shared_memory = shmat(shmid, (void *)0, 0);
if(shared_memory == (void *)-1)
{
printf("\nshmat failed\n");
exit(EXIT_FAILURE);
}
printf("Memory attached 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("\nwaiting for client...\n");
        }
        printf("Enter some text: ");
        fgets(buffer, MEM_SZ, stdin);
        strcpy(shared_stuff->some_text, buffer);
        shared_stuff->written_by_you = 1;
        if(strncmp(buffer, "end", 3) == 0)
        {
                running = 0;
        }
}
if(shmdt(shared_memory) == -1)
{
printf("shmdt failed\n");
exit(EXIT_FAILURE);
}
exit(EXIT_SUCCESS);
}

 
$ cat consumer.c
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#define MEM_SZ 4096
struct shared_use_st
{
int written_by_you;
char some_text[MEM_SZ];
};
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, MEM_SZ, 0666 | IPC_CREAT);
        if(shmid ==-1)
        {
        printf("shmget failed\n");
        exit(EXIT_FAILURE);
        }
        shared_memory = shmat(shmid, (void *)0, 0);
        if(shared_memory == (void *)-1)
        {
        printf("\nshmat failed\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)
{
        printf("shmdt failed\n");
        exit(EXIT_FAILURE);
}
if(shmctl(shmid, IPC_RMID, 0)==-1)
{
printf("shmctl(IPC_RMID)failed\n");
exit(EXIT_FAILURE);
}
exit(EXIT_SUCCESS);
}

IPC_PRIVATE