linux共享内存

#include <stdio.h>
#include <string.h>
#include <semaphore.h>
#include <sys/shm.h>
#include <unistd.h>
#include <fcntl.h>

#define BUFFER_SIZE 4

int main()
{
int shmid = shmget((key_t)1234, sizeof(int) * BUFFER_SIZE, 0644 | IPC_CREAT);

if ( -1 == shmid )
{
printf("shmget failed!\n");
return 0;
}

void *shm = shmat(shmid, NULL, 0);
if ((void *)-1 == shm)
{
printf("shmat failed!\n");
return 0;
}

int *sharedbuffer = (int *)shm;
memset(sharedbuffer, -1, sizeof(int) * BUFFER_SIZE);

int index = 0;
while (index <= 20)
{
for (int i = 0; i < 4; i++)
{
if (-1 == sharedbuffer[i])
{
sharedbuffer[i] = ++index;
printf("product: %d\n", sharedbuffer[i]);
break;
}
}
}
if (-1 == shmdt((void *)sharedbuffer))
{
printf("shmdt failed!\n");
}
}

#include <stdio.h>
#include <string.h>
#include <semaphore.h>
#include <sys/shm.h>
#include <unistd.h>
#include <fcntl.h>

#define BUFFER_SIZE 4

int main()
{
int shmid = shmget((key_t)1234, sizeof(int) * BUFFER_SIZE, 0644 | IPC_CREAT);

if ( -1 == shmid )
{
printf("shmget failed!\n");
return 0;
}

void *shm = shmat(shmid, NULL, 0);
if ((void *)-1 == shm)
{
printf("shmat failed!\n");
return 0;
}

int *sharedbuffer = (int *)shm;

int run = 1;
while (run)
{
for (int i = 0; i < 4; i++)
{
if (-1 != sharedbuffer[i])
{
printf("consumer: %d\n", sharedbuffer[i] );
if ( 20 == sharedbuffer[i] )
{
run = 0;
}
sharedbuffer[i] = -1;
break;
}
}
}
if (-1 == shmdt((void *)sharedbuffer))
{
printf("shmdt failed!\n");
}
}