1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
4*4882a593Smuzhiyun */
5*4882a593Smuzhiyun
6*4882a593Smuzhiyun #include <stddef.h>
7*4882a593Smuzhiyun #include <errno.h>
8*4882a593Smuzhiyun #include <fcntl.h>
9*4882a593Smuzhiyun #include "chan_user.h"
10*4882a593Smuzhiyun #include <os.h>
11*4882a593Smuzhiyun
12*4882a593Smuzhiyun /* This address is used only as a unique identifier */
13*4882a593Smuzhiyun static int null_chan;
14*4882a593Smuzhiyun
null_init(char * str,int device,const struct chan_opts * opts)15*4882a593Smuzhiyun static void *null_init(char *str, int device, const struct chan_opts *opts)
16*4882a593Smuzhiyun {
17*4882a593Smuzhiyun return &null_chan;
18*4882a593Smuzhiyun }
19*4882a593Smuzhiyun
null_open(int input,int output,int primary,void * d,char ** dev_out)20*4882a593Smuzhiyun static int null_open(int input, int output, int primary, void *d,
21*4882a593Smuzhiyun char **dev_out)
22*4882a593Smuzhiyun {
23*4882a593Smuzhiyun int fd;
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun *dev_out = NULL;
26*4882a593Smuzhiyun
27*4882a593Smuzhiyun fd = open(DEV_NULL, O_RDWR);
28*4882a593Smuzhiyun return (fd < 0) ? -errno : fd;
29*4882a593Smuzhiyun }
30*4882a593Smuzhiyun
null_read(int fd,char * c_out,void * unused)31*4882a593Smuzhiyun static int null_read(int fd, char *c_out, void *unused)
32*4882a593Smuzhiyun {
33*4882a593Smuzhiyun return -ENODEV;
34*4882a593Smuzhiyun }
35*4882a593Smuzhiyun
null_free(void * data)36*4882a593Smuzhiyun static void null_free(void *data)
37*4882a593Smuzhiyun {
38*4882a593Smuzhiyun }
39*4882a593Smuzhiyun
40*4882a593Smuzhiyun const struct chan_ops null_ops = {
41*4882a593Smuzhiyun .type = "null",
42*4882a593Smuzhiyun .init = null_init,
43*4882a593Smuzhiyun .open = null_open,
44*4882a593Smuzhiyun .close = generic_close,
45*4882a593Smuzhiyun .read = null_read,
46*4882a593Smuzhiyun .write = generic_write,
47*4882a593Smuzhiyun .console_write = generic_console_write,
48*4882a593Smuzhiyun .window_size = generic_window_size,
49*4882a593Smuzhiyun .free = null_free,
50*4882a593Smuzhiyun .winch = 0,
51*4882a593Smuzhiyun };
52