/dev/dog

After reading a post on edd's blog about a cat and that it wasn't a device I though ?Why not?

14:12 <> the cat is not a device driver ffs
14:13 < #4> cat /dev/cat ;)

So her you go. Now you can have a device called dog in Linux and feed it with
echo "Food" > /dev/dog
cat /dev/dog

If you want more features just tell me :)

 1: /*
 2:  * The Dog kernel module
 3:  * Creates a /dev/dog
 4:  *
 5:  * Hoffmann Geerd-Dietger 
 6:  * Thx to:
 7:  * Valerie Henson 
 8:  *
 9:  */
10: #define BUFFER 80
11: 
12: #include <linux/fs.h>
13: #include <linux/init.h>
14: #include <linux/miscdevice.h>
15: #include <linux/module.h>
16: #include <asm/uaccess.h>
17: 
18: MODULE_LICENSE("DUAL GPL/BSD");
19: MODULE_AUTHOR("Hoffmann Geerd-Dietger ");
20: MODULE_DESCRIPTION("A little dog living in /dev");
21: MODULE_VERSION("0.1");
22: 
23: 
24: static char hello_str[BUFFER]="Hello Master, just echo to me and then cat\n";
25: 
26: static ssize_t dog_write(struct file *filp, const char __user *buff,
27:                            size_t count, loff_t *offp)
28: {
29:   /* We don't care just chop it off */
30:   if (count >= BUFFER)
31:     count = BUFFER;
32: 
33:   if (copy_from_user(hello_str,buff, count))
34:     return -EINVAL;
35: 
36:   return count;
37: }
38: 
39: 
40: static ssize_t dog_read(struct file * file, char * buf,
41:                           size_t count, loff_t *ppos)
42: {
43: 
44:   if (count < BUFFER)
45:     return -EINVAL;
46: 
47:   if (*ppos != 0)
48:     return 0;
49: 
50:   if (copy_to_user(buf, hello_str, BUFFER))
51:     return -EINVAL;
52: 
53:   *ppos =  BUFFER;
54: 
55:   return BUFFER;
56: }
57: 
58: 
59: static const struct file_operations dog_fops = {
60:   .owner    = THIS_MODULE,
61:   .read     = dog_read,
62:   .write    = dog_write,
63: };
64: 
65: static struct miscdevice dog_dev = {MISC_DYNAMIC_MINOR,"dog",&dog_fops };
66: 
67: static int __init
68: dog_init(void)
69: {
70:   int ret;
71: 
72:   ret = misc_register(&dog_dev);
73:   if (ret)
74:     printk(KERN_ERR
75:            "Unable to register \"Dog\" misc device\n");
76: 
77:   printk("dog: Woof Woof\n");
78: 
79:   return ret;
80: }
81: 
82: module_init(dog_init);
83: 
84: static void __exit
85: dog_exit(void)
86: {
87:   misc_deregister(&dog_dev);
88:   printk("dog: Grrrrrrrrrrrrrrrrr");
89: }
90: 
91: module_exit(dog_exit); 

Makefile:

obj-m := dog_dev.o

KDIR  := /lib/modules/$(shell uname -r)/build
PWD   := $(shell pwd)

default:
      $(MAKE) -C $(KDIR) M=$(PWD) modules

Of course you have to insmod the module