xref: /linux/arch/um/drivers/null.c (revision c537b994505099b7197e7d3125b942ecbcc51eb6)
1 /*
2  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
3  * Licensed under the GPL
4  */
5 
6 #include <stdlib.h>
7 #include <errno.h>
8 #include "chan_user.h"
9 #include "os.h"
10 
11 /* This address is used only as a unique identifer */
12 static int null_chan;
13 
14 static void *null_init(char *str, int device, const struct chan_opts *opts)
15 {
16 	return(&null_chan);
17 }
18 
19 static int null_open(int input, int output, int primary, void *d,
20 		     char **dev_out)
21 {
22 	*dev_out = NULL;
23 	return(os_open_file(DEV_NULL, of_rdwr(OPENFLAGS()), 0));
24 }
25 
26 static int null_read(int fd, char *c_out, void *unused)
27 {
28 	return(-ENODEV);
29 }
30 
31 static void null_free(void *data)
32 {
33 }
34 
35 const struct chan_ops null_ops = {
36 	.type		= "null",
37 	.init		= null_init,
38 	.open		= null_open,
39 	.close		= generic_close,
40 	.read		= null_read,
41 	.write		= generic_write,
42 	.console_write	= generic_console_write,
43 	.window_size	= generic_window_size,
44 	.free		= null_free,
45 	.winch		= 0,
46 };
47 
48 /*
49  * Overrides for Emacs so that we follow Linus's tabbing style.
50  * Emacs will notice this stuff at the end of the file and automatically
51  * adjust the settings for this buffer only.  This must remain at the end
52  * of the file.
53  * ---------------------------------------------------------------------------
54  * Local variables:
55  * c-file-style: "linux"
56  * End:
57  */
58