[C++] 纯文本查看 复制代码
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h> /* current and everything */
#include <linux/kernel.h> /* printk() */
#include <linux/fs.h> /* everything... */
#include <linux/types.h> /* size_t */
#include <linux/wait.h>
MODULE_LICENSE("Dual BSD/GPL");
static int sleepy_major = 0;
static DECLARE_WAIT_QUEUE_HEAD(wq);
static int flag = 0;
ssize_t sleepy_read (struct file *filp, char __user *buf, size_t count, loff_t *pos)
{
printk(KERN_DEBUG "process %i (%s) going to sleep\n",
current->pid, current->comm);
wait_event_interruptible(wq, flag != 0);
flag = 0;
printk(KERN_DEBUG "awoken %i (%s)\n", current->pid, current->comm);
return 0; /* EOF */
}
ssize_t sleepy_write (struct file *filp, const char __user *buf, size_t count,
loff_t *pos)
{
printk(KERN_DEBUG "process %i (%s) awakening the readers...\n",
current->pid, current->comm);
flag = 1;
wake_up_interruptible(&wq);
return count; /* succeed, to avoid retrial */
}
struct file_operations sleepy_fops = {
.owner = THIS_MODULE,
.read = sleepy_read,
.write = sleepy_write,
};
int sleepy_init(void)
{
int result;
/*
* * Register your major, and accept a dynamic number
* */
result = register_chrdev(sleepy_major, "sleepy", &sleepy_fops);
if (result < 0)
return result;
if (sleepy_major == 0)
sleepy_major = result; /* dynamic */
return 0;
}
void sleepy_cleanup(void)
{
unregister_chrdev(sleepy_major, "sleepy");
}
module_init(sleepy_init);
module_exit(sleepy_cleanup);
[C++] 纯文本查看 复制代码
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int main(void)
{
int fd;
char buf[100];
if((fd = open ("/dev/sleepy", O_RDONLY)) < 0) {
perror ("open");
exit (EXIT_FAILURE);
}
printf ("ready to read sleepy device and waiting data coming...\n");
if(read(fd, buf, 10) == -1) {
perror ("read");
exit (EXIT_FAILURE);
}
printf ("OK, i got it, bye\n");
return (0);
}
[C++] 纯文本查看 复制代码
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
int main(void)
{
int fd;
char buf[10] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j'};
if((fd = open ("/dev/sleepy", O_RDWR)) < 0) {
perror ("open");
exit (EXIT_FAILURE);
}
printf ("write 10 characters to buffer.\n");
if(write(fd, buf, 10) == -1) {
perror ("write");
exit (EXIT_FAILURE);
}
printf ("write over.\n");
return (0);
}