writer.c

此源码是著名的教材BeginningLinux Programming中文名字叫Linux程序设计书中的源代码

#include "sharemem.h"

#define SHM_SIZE 1024

int main()
{
	int	  semid, shmid;
	char  *shmaddr;
	char  write_str[SHM_SIZE];
	
	if ((shmid = createshm (".", 'm', SHM_SIZE)) == -1)
	{
		exit(1);
	}
	
	if ((shmaddr = shmat (shmid, (char *)0, 0)) ==(char *)-1)
	{
		perror ("attach shared memory error!\n");
		exit (1);
	}
	
	if ((semid = createsem (".", 's', 1, 1)) == -1)
	{
		exit (1);
	}
	
	while (1)
	{
		wait_sem (semid, 0);
		sem_p (semid, 0);  /*P操作*/
		
		printf ("writer: ");
		fgets (write_str, 1024, stdin);
		int len = strlen (write_str) - 1;
		write_str[len] = '\0';
		strcpy (shmaddr, write_str);
		sleep (10);	 /*使reader处于阻塞状态*/
		
		sem_v (semid, 0);  /*V操作*/
		sleep (10);	 /*等待reader进行读操作*/
		
	}
}