// SPDX-License-Identifier: GPL-2.0
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/tty.h>
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#include <linux/module.h>
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/*
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* n_null.c - Null line discipline used in the failure path
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*
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* Copyright (C) Intel 2017
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*/
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static int n_null_open(struct tty_struct *tty)
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{
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return 0;
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}
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static void n_null_close(struct tty_struct *tty)
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{
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}
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static ssize_t n_null_read(struct tty_struct *tty, struct file *file,
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unsigned char *buf, size_t nr,
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void **cookie, unsigned long offset)
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{
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return -EOPNOTSUPP;
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}
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static ssize_t n_null_write(struct tty_struct *tty, struct file *file,
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const unsigned char *buf, size_t nr)
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{
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return -EOPNOTSUPP;
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}
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static void n_null_receivebuf(struct tty_struct *tty,
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const unsigned char *cp, char *fp,
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int cnt)
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{
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}
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static struct tty_ldisc_ops null_ldisc = {
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.owner = THIS_MODULE,
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.magic = TTY_LDISC_MAGIC,
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.name = "n_null",
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.open = n_null_open,
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.close = n_null_close,
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.read = n_null_read,
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.write = n_null_write,
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.receive_buf = n_null_receivebuf
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};
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static int __init n_null_init(void)
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{
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BUG_ON(tty_register_ldisc(N_NULL, &null_ldisc));
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return 0;
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}
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static void __exit n_null_exit(void)
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{
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tty_unregister_ldisc(N_NULL);
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}
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module_init(n_null_init);
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module_exit(n_null_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Alan Cox");
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MODULE_ALIAS_LDISC(N_NULL);
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MODULE_DESCRIPTION("Null ldisc driver");
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