client1.c

让你了解Unix进程间的通信是如何实现的

#include	"unpipc.h"

struct shmstruct {	/* struct stored in shared memory */
  int	count;
};
sem_t	*mutex;		/* pointer to named semaphore */

int
main(int argc, char **argv)
{
	int		fd, i, nloop;
	pid_t	pid;
	struct shmstruct	*ptr;

	if (argc != 4)
		err_quit("usage: client1 <shmname> <semname> <#loops>");
	nloop = atoi(argv[3]);

	fd = Shm_open(Px_ipc_name(argv[1]), O_RDWR, FILE_MODE);
	ptr = Mmap(NULL, sizeof(struct shmstruct), PROT_READ | PROT_WRITE,
			   MAP_SHARED, fd, 0);
	Close(fd);

	mutex = Sem_open(Px_ipc_name(argv[2]), 0);

	pid = getpid();
	for (i = 0; i < nloop; i++) {
		Sem_wait(mutex);
		printf("pid %ld: %d\n", (long) pid, ptr->count++);
		Sem_post(mutex);
	}
	exit(0);
}