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