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2460 lines
61 KiB
2460 lines
61 KiB
// SPDX-License-Identifier: GPL-1.0+ |
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/* |
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* n_tty.c --- implements the N_TTY line discipline. |
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* |
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* This code used to be in tty_io.c, but things are getting hairy |
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* enough that it made sense to split things off. (The N_TTY |
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* processing has changed so much that it's hardly recognizable, |
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* anyway...) |
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* |
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* Note that the open routine for N_TTY is guaranteed never to return |
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* an error. This is because Linux will fall back to setting a line |
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* to N_TTY if it can not switch to any other line discipline. |
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* |
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* Written by Theodore Ts'o, Copyright 1994. |
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* |
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* This file also contains code originally written by Linus Torvalds, |
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* Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994. |
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* |
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* Reduced memory usage for older ARM systems - Russell King. |
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* |
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* 2000/01/20 Fixed SMP locking on put_tty_queue using bits of |
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* the patch by Andrew J. Kroll <[email protected]> |
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* who actually finally proved there really was a race. |
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* |
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* 2002/03/18 Implemented n_tty_wakeup to send SIGIO POLL_OUTs to |
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* waiting writing processes-Sapan Bhatia <[email protected]>. |
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* Also fixed a bug in BLOCKING mode where n_tty_write returns |
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* EAGAIN |
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*/ |
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|
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#include <linux/types.h> |
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#include <linux/major.h> |
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#include <linux/errno.h> |
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#include <linux/signal.h> |
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#include <linux/fcntl.h> |
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#include <linux/sched.h> |
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#include <linux/interrupt.h> |
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#include <linux/tty.h> |
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#include <linux/timer.h> |
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#include <linux/ctype.h> |
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#include <linux/mm.h> |
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#include <linux/string.h> |
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#include <linux/slab.h> |
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#include <linux/poll.h> |
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#include <linux/bitops.h> |
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#include <linux/audit.h> |
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#include <linux/file.h> |
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#include <linux/uaccess.h> |
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#include <linux/module.h> |
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#include <linux/ratelimit.h> |
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#include <linux/vmalloc.h> |
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#include "tty.h" |
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|
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/* |
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* Until this number of characters is queued in the xmit buffer, select will |
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* return "we have room for writes". |
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*/ |
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#define WAKEUP_CHARS 256 |
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|
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/* |
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* This defines the low- and high-watermarks for throttling and |
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* unthrottling the TTY driver. These watermarks are used for |
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* controlling the space in the read buffer. |
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*/ |
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#define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */ |
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#define TTY_THRESHOLD_UNTHROTTLE 128 |
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|
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/* |
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* Special byte codes used in the echo buffer to represent operations |
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* or special handling of characters. Bytes in the echo buffer that |
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* are not part of such special blocks are treated as normal character |
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* codes. |
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*/ |
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#define ECHO_OP_START 0xff |
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#define ECHO_OP_MOVE_BACK_COL 0x80 |
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#define ECHO_OP_SET_CANON_COL 0x81 |
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#define ECHO_OP_ERASE_TAB 0x82 |
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|
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#define ECHO_COMMIT_WATERMARK 256 |
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#define ECHO_BLOCK 256 |
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#define ECHO_DISCARD_WATERMARK N_TTY_BUF_SIZE - (ECHO_BLOCK + 32) |
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|
|
|
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#undef N_TTY_TRACE |
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#ifdef N_TTY_TRACE |
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# define n_tty_trace(f, args...) trace_printk(f, ##args) |
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#else |
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# define n_tty_trace(f, args...) no_printk(f, ##args) |
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#endif |
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|
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struct n_tty_data { |
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/* producer-published */ |
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size_t read_head; |
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size_t commit_head; |
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size_t canon_head; |
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size_t echo_head; |
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size_t echo_commit; |
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size_t echo_mark; |
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DECLARE_BITMAP(char_map, 256); |
|
|
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/* private to n_tty_receive_overrun (single-threaded) */ |
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unsigned long overrun_time; |
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int num_overrun; |
|
|
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/* non-atomic */ |
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bool no_room; |
|
|
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/* must hold exclusive termios_rwsem to reset these */ |
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unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1; |
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unsigned char push:1; |
|
|
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/* shared by producer and consumer */ |
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char read_buf[N_TTY_BUF_SIZE]; |
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DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE); |
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unsigned char echo_buf[N_TTY_BUF_SIZE]; |
|
|
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/* consumer-published */ |
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size_t read_tail; |
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size_t line_start; |
|
|
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/* protected by output lock */ |
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unsigned int column; |
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unsigned int canon_column; |
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size_t echo_tail; |
|
|
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struct mutex atomic_read_lock; |
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struct mutex output_lock; |
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}; |
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|
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#define MASK(x) ((x) & (N_TTY_BUF_SIZE - 1)) |
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|
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static inline size_t read_cnt(struct n_tty_data *ldata) |
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{ |
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return ldata->read_head - ldata->read_tail; |
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} |
|
|
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static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i) |
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{ |
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return ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)]; |
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} |
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|
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static inline unsigned char *read_buf_addr(struct n_tty_data *ldata, size_t i) |
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{ |
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return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)]; |
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} |
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|
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static inline unsigned char echo_buf(struct n_tty_data *ldata, size_t i) |
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{ |
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smp_rmb(); /* Matches smp_wmb() in add_echo_byte(). */ |
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return ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)]; |
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} |
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|
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static inline unsigned char *echo_buf_addr(struct n_tty_data *ldata, size_t i) |
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{ |
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return &ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)]; |
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} |
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|
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/* If we are not echoing the data, perhaps this is a secret so erase it */ |
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static void zero_buffer(struct tty_struct *tty, u8 *buffer, int size) |
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{ |
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bool icanon = !!L_ICANON(tty); |
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bool no_echo = !L_ECHO(tty); |
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|
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if (icanon && no_echo) |
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memset(buffer, 0x00, size); |
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} |
|
|
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static void tty_copy(struct tty_struct *tty, void *to, size_t tail, size_t n) |
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{ |
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struct n_tty_data *ldata = tty->disc_data; |
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size_t size = N_TTY_BUF_SIZE - tail; |
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void *from = read_buf_addr(ldata, tail); |
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|
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if (n > size) { |
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tty_audit_add_data(tty, from, size); |
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memcpy(to, from, size); |
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zero_buffer(tty, from, size); |
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to += size; |
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n -= size; |
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from = ldata->read_buf; |
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} |
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|
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tty_audit_add_data(tty, from, n); |
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memcpy(to, from, n); |
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zero_buffer(tty, from, n); |
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} |
|
|
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/** |
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* n_tty_kick_worker - start input worker (if required) |
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* @tty: terminal |
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* |
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* Re-schedules the flip buffer work if it may have stopped |
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* |
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* Caller holds exclusive termios_rwsem |
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* or |
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* n_tty_read()/consumer path: |
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* holds non-exclusive termios_rwsem |
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*/ |
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|
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static void n_tty_kick_worker(struct tty_struct *tty) |
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{ |
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struct n_tty_data *ldata = tty->disc_data; |
|
|
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/* Did the input worker stop? Restart it */ |
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if (unlikely(ldata->no_room)) { |
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ldata->no_room = 0; |
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|
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WARN_RATELIMIT(tty->port->itty == NULL, |
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"scheduling with invalid itty\n"); |
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/* see if ldisc has been killed - if so, this means that |
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* even though the ldisc has been halted and ->buf.work |
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* cancelled, ->buf.work is about to be rescheduled |
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*/ |
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WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags), |
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"scheduling buffer work for halted ldisc\n"); |
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tty_buffer_restart_work(tty->port); |
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} |
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} |
|
|
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static ssize_t chars_in_buffer(struct tty_struct *tty) |
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{ |
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struct n_tty_data *ldata = tty->disc_data; |
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ssize_t n = 0; |
|
|
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if (!ldata->icanon) |
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n = ldata->commit_head - ldata->read_tail; |
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else |
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n = ldata->canon_head - ldata->read_tail; |
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return n; |
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} |
|
|
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/** |
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* n_tty_write_wakeup - asynchronous I/O notifier |
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* @tty: tty device |
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* |
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* Required for the ptys, serial driver etc. since processes |
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* that attach themselves to the master and rely on ASYNC |
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* IO must be woken up |
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*/ |
|
|
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static void n_tty_write_wakeup(struct tty_struct *tty) |
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{ |
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clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
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kill_fasync(&tty->fasync, SIGIO, POLL_OUT); |
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} |
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|
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static void n_tty_check_throttle(struct tty_struct *tty) |
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{ |
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struct n_tty_data *ldata = tty->disc_data; |
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|
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/* |
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* Check the remaining room for the input canonicalization |
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* mode. We don't want to throttle the driver if we're in |
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* canonical mode and don't have a newline yet! |
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*/ |
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if (ldata->icanon && ldata->canon_head == ldata->read_tail) |
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return; |
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|
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while (1) { |
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int throttled; |
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tty_set_flow_change(tty, TTY_THROTTLE_SAFE); |
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if (N_TTY_BUF_SIZE - read_cnt(ldata) >= TTY_THRESHOLD_THROTTLE) |
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break; |
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throttled = tty_throttle_safe(tty); |
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if (!throttled) |
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break; |
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} |
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__tty_set_flow_change(tty, 0); |
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} |
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|
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static void n_tty_check_unthrottle(struct tty_struct *tty) |
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{ |
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if (tty->driver->type == TTY_DRIVER_TYPE_PTY) { |
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if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE) |
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return; |
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n_tty_kick_worker(tty); |
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tty_wakeup(tty->link); |
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return; |
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} |
|
|
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/* If there is enough space in the read buffer now, let the |
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* low-level driver know. We use chars_in_buffer() to |
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* check the buffer, as it now knows about canonical mode. |
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* Otherwise, if the driver is throttled and the line is |
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* longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode, |
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* we won't get any more characters. |
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*/ |
|
|
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while (1) { |
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int unthrottled; |
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tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE); |
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if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE) |
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break; |
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n_tty_kick_worker(tty); |
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unthrottled = tty_unthrottle_safe(tty); |
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if (!unthrottled) |
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break; |
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} |
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__tty_set_flow_change(tty, 0); |
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} |
|
|
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/** |
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* put_tty_queue - add character to tty |
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* @c: character |
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* @ldata: n_tty data |
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* |
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* Add a character to the tty read_buf queue. |
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* |
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* n_tty_receive_buf()/producer path: |
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* caller holds non-exclusive termios_rwsem |
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*/ |
|
|
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static inline void put_tty_queue(unsigned char c, struct n_tty_data *ldata) |
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{ |
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*read_buf_addr(ldata, ldata->read_head) = c; |
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ldata->read_head++; |
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} |
|
|
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/** |
|
* reset_buffer_flags - reset buffer state |
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* @ldata: line disc data to reset |
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* |
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* Reset the read buffer counters and clear the flags. |
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* Called from n_tty_open() and n_tty_flush_buffer(). |
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* |
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* Locking: caller holds exclusive termios_rwsem |
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* (or locking is not required) |
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*/ |
|
|
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static void reset_buffer_flags(struct n_tty_data *ldata) |
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{ |
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ldata->read_head = ldata->canon_head = ldata->read_tail = 0; |
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ldata->commit_head = 0; |
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ldata->line_start = 0; |
|
|
|
ldata->erasing = 0; |
|
bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE); |
|
ldata->push = 0; |
|
} |
|
|
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static void n_tty_packet_mode_flush(struct tty_struct *tty) |
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{ |
|
unsigned long flags; |
|
|
|
if (tty->link->ctrl.packet) { |
|
spin_lock_irqsave(&tty->ctrl.lock, flags); |
|
tty->ctrl.pktstatus |= TIOCPKT_FLUSHREAD; |
|
spin_unlock_irqrestore(&tty->ctrl.lock, flags); |
|
wake_up_interruptible(&tty->link->read_wait); |
|
} |
|
} |
|
|
|
/** |
|
* n_tty_flush_buffer - clean input queue |
|
* @tty: terminal device |
|
* |
|
* Flush the input buffer. Called when the tty layer wants the |
|
* buffer flushed (eg at hangup) or when the N_TTY line discipline |
|
* internally has to clean the pending queue (for example some signals). |
|
* |
|
* Holds termios_rwsem to exclude producer/consumer while |
|
* buffer indices are reset. |
|
* |
|
* Locking: ctrl.lock, exclusive termios_rwsem |
|
*/ |
|
|
|
static void n_tty_flush_buffer(struct tty_struct *tty) |
|
{ |
|
down_write(&tty->termios_rwsem); |
|
reset_buffer_flags(tty->disc_data); |
|
n_tty_kick_worker(tty); |
|
|
|
if (tty->link) |
|
n_tty_packet_mode_flush(tty); |
|
up_write(&tty->termios_rwsem); |
|
} |
|
|
|
/** |
|
* is_utf8_continuation - utf8 multibyte check |
|
* @c: byte to check |
|
* |
|
* Returns true if the utf8 character 'c' is a multibyte continuation |
|
* character. We use this to correctly compute the on screen size |
|
* of the character when printing |
|
*/ |
|
|
|
static inline int is_utf8_continuation(unsigned char c) |
|
{ |
|
return (c & 0xc0) == 0x80; |
|
} |
|
|
|
/** |
|
* is_continuation - multibyte check |
|
* @c: byte to check |
|
* @tty: terminal device |
|
* |
|
* Returns true if the utf8 character 'c' is a multibyte continuation |
|
* character and the terminal is in unicode mode. |
|
*/ |
|
|
|
static inline int is_continuation(unsigned char c, struct tty_struct *tty) |
|
{ |
|
return I_IUTF8(tty) && is_utf8_continuation(c); |
|
} |
|
|
|
/** |
|
* do_output_char - output one character |
|
* @c: character (or partial unicode symbol) |
|
* @tty: terminal device |
|
* @space: space available in tty driver write buffer |
|
* |
|
* This is a helper function that handles one output character |
|
* (including special characters like TAB, CR, LF, etc.), |
|
* doing OPOST processing and putting the results in the |
|
* tty driver's write buffer. |
|
* |
|
* Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY |
|
* and NLDLY. They simply aren't relevant in the world today. |
|
* If you ever need them, add them here. |
|
* |
|
* Returns the number of bytes of buffer space used or -1 if |
|
* no space left. |
|
* |
|
* Locking: should be called under the output_lock to protect |
|
* the column state and space left in the buffer |
|
*/ |
|
|
|
static int do_output_char(unsigned char c, struct tty_struct *tty, int space) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
int spaces; |
|
|
|
if (!space) |
|
return -1; |
|
|
|
switch (c) { |
|
case '\n': |
|
if (O_ONLRET(tty)) |
|
ldata->column = 0; |
|
if (O_ONLCR(tty)) { |
|
if (space < 2) |
|
return -1; |
|
ldata->canon_column = ldata->column = 0; |
|
tty->ops->write(tty, "\r\n", 2); |
|
return 2; |
|
} |
|
ldata->canon_column = ldata->column; |
|
break; |
|
case '\r': |
|
if (O_ONOCR(tty) && ldata->column == 0) |
|
return 0; |
|
if (O_OCRNL(tty)) { |
|
c = '\n'; |
|
if (O_ONLRET(tty)) |
|
ldata->canon_column = ldata->column = 0; |
|
break; |
|
} |
|
ldata->canon_column = ldata->column = 0; |
|
break; |
|
case '\t': |
|
spaces = 8 - (ldata->column & 7); |
|
if (O_TABDLY(tty) == XTABS) { |
|
if (space < spaces) |
|
return -1; |
|
ldata->column += spaces; |
|
tty->ops->write(tty, " ", spaces); |
|
return spaces; |
|
} |
|
ldata->column += spaces; |
|
break; |
|
case '\b': |
|
if (ldata->column > 0) |
|
ldata->column--; |
|
break; |
|
default: |
|
if (!iscntrl(c)) { |
|
if (O_OLCUC(tty)) |
|
c = toupper(c); |
|
if (!is_continuation(c, tty)) |
|
ldata->column++; |
|
} |
|
break; |
|
} |
|
|
|
tty_put_char(tty, c); |
|
return 1; |
|
} |
|
|
|
/** |
|
* process_output - output post processor |
|
* @c: character (or partial unicode symbol) |
|
* @tty: terminal device |
|
* |
|
* Output one character with OPOST processing. |
|
* Returns -1 when the output device is full and the character |
|
* must be retried. |
|
* |
|
* Locking: output_lock to protect column state and space left |
|
* (also, this is called from n_tty_write under the |
|
* tty layer write lock) |
|
*/ |
|
|
|
static int process_output(unsigned char c, struct tty_struct *tty) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
int space, retval; |
|
|
|
mutex_lock(&ldata->output_lock); |
|
|
|
space = tty_write_room(tty); |
|
retval = do_output_char(c, tty, space); |
|
|
|
mutex_unlock(&ldata->output_lock); |
|
if (retval < 0) |
|
return -1; |
|
else |
|
return 0; |
|
} |
|
|
|
/** |
|
* process_output_block - block post processor |
|
* @tty: terminal device |
|
* @buf: character buffer |
|
* @nr: number of bytes to output |
|
* |
|
* Output a block of characters with OPOST processing. |
|
* Returns the number of characters output. |
|
* |
|
* This path is used to speed up block console writes, among other |
|
* things when processing blocks of output data. It handles only |
|
* the simple cases normally found and helps to generate blocks of |
|
* symbols for the console driver and thus improve performance. |
|
* |
|
* Locking: output_lock to protect column state and space left |
|
* (also, this is called from n_tty_write under the |
|
* tty layer write lock) |
|
*/ |
|
|
|
static ssize_t process_output_block(struct tty_struct *tty, |
|
const unsigned char *buf, unsigned int nr) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
int space; |
|
int i; |
|
const unsigned char *cp; |
|
|
|
mutex_lock(&ldata->output_lock); |
|
|
|
space = tty_write_room(tty); |
|
if (space <= 0) { |
|
mutex_unlock(&ldata->output_lock); |
|
return space; |
|
} |
|
if (nr > space) |
|
nr = space; |
|
|
|
for (i = 0, cp = buf; i < nr; i++, cp++) { |
|
unsigned char c = *cp; |
|
|
|
switch (c) { |
|
case '\n': |
|
if (O_ONLRET(tty)) |
|
ldata->column = 0; |
|
if (O_ONLCR(tty)) |
|
goto break_out; |
|
ldata->canon_column = ldata->column; |
|
break; |
|
case '\r': |
|
if (O_ONOCR(tty) && ldata->column == 0) |
|
goto break_out; |
|
if (O_OCRNL(tty)) |
|
goto break_out; |
|
ldata->canon_column = ldata->column = 0; |
|
break; |
|
case '\t': |
|
goto break_out; |
|
case '\b': |
|
if (ldata->column > 0) |
|
ldata->column--; |
|
break; |
|
default: |
|
if (!iscntrl(c)) { |
|
if (O_OLCUC(tty)) |
|
goto break_out; |
|
if (!is_continuation(c, tty)) |
|
ldata->column++; |
|
} |
|
break; |
|
} |
|
} |
|
break_out: |
|
i = tty->ops->write(tty, buf, i); |
|
|
|
mutex_unlock(&ldata->output_lock); |
|
return i; |
|
} |
|
|
|
/** |
|
* process_echoes - write pending echo characters |
|
* @tty: terminal device |
|
* |
|
* Write previously buffered echo (and other ldisc-generated) |
|
* characters to the tty. |
|
* |
|
* Characters generated by the ldisc (including echoes) need to |
|
* be buffered because the driver's write buffer can fill during |
|
* heavy program output. Echoing straight to the driver will |
|
* often fail under these conditions, causing lost characters and |
|
* resulting mismatches of ldisc state information. |
|
* |
|
* Since the ldisc state must represent the characters actually sent |
|
* to the driver at the time of the write, operations like certain |
|
* changes in column state are also saved in the buffer and executed |
|
* here. |
|
* |
|
* A circular fifo buffer is used so that the most recent characters |
|
* are prioritized. Also, when control characters are echoed with a |
|
* prefixed "^", the pair is treated atomically and thus not separated. |
|
* |
|
* Locking: callers must hold output_lock |
|
*/ |
|
|
|
static size_t __process_echoes(struct tty_struct *tty) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
int space, old_space; |
|
size_t tail; |
|
unsigned char c; |
|
|
|
old_space = space = tty_write_room(tty); |
|
|
|
tail = ldata->echo_tail; |
|
while (MASK(ldata->echo_commit) != MASK(tail)) { |
|
c = echo_buf(ldata, tail); |
|
if (c == ECHO_OP_START) { |
|
unsigned char op; |
|
int no_space_left = 0; |
|
|
|
/* |
|
* Since add_echo_byte() is called without holding |
|
* output_lock, we might see only portion of multi-byte |
|
* operation. |
|
*/ |
|
if (MASK(ldata->echo_commit) == MASK(tail + 1)) |
|
goto not_yet_stored; |
|
/* |
|
* If the buffer byte is the start of a multi-byte |
|
* operation, get the next byte, which is either the |
|
* op code or a control character value. |
|
*/ |
|
op = echo_buf(ldata, tail + 1); |
|
|
|
switch (op) { |
|
case ECHO_OP_ERASE_TAB: { |
|
unsigned int num_chars, num_bs; |
|
|
|
if (MASK(ldata->echo_commit) == MASK(tail + 2)) |
|
goto not_yet_stored; |
|
num_chars = echo_buf(ldata, tail + 2); |
|
|
|
/* |
|
* Determine how many columns to go back |
|
* in order to erase the tab. |
|
* This depends on the number of columns |
|
* used by other characters within the tab |
|
* area. If this (modulo 8) count is from |
|
* the start of input rather than from a |
|
* previous tab, we offset by canon column. |
|
* Otherwise, tab spacing is normal. |
|
*/ |
|
if (!(num_chars & 0x80)) |
|
num_chars += ldata->canon_column; |
|
num_bs = 8 - (num_chars & 7); |
|
|
|
if (num_bs > space) { |
|
no_space_left = 1; |
|
break; |
|
} |
|
space -= num_bs; |
|
while (num_bs--) { |
|
tty_put_char(tty, '\b'); |
|
if (ldata->column > 0) |
|
ldata->column--; |
|
} |
|
tail += 3; |
|
break; |
|
} |
|
case ECHO_OP_SET_CANON_COL: |
|
ldata->canon_column = ldata->column; |
|
tail += 2; |
|
break; |
|
|
|
case ECHO_OP_MOVE_BACK_COL: |
|
if (ldata->column > 0) |
|
ldata->column--; |
|
tail += 2; |
|
break; |
|
|
|
case ECHO_OP_START: |
|
/* This is an escaped echo op start code */ |
|
if (!space) { |
|
no_space_left = 1; |
|
break; |
|
} |
|
tty_put_char(tty, ECHO_OP_START); |
|
ldata->column++; |
|
space--; |
|
tail += 2; |
|
break; |
|
|
|
default: |
|
/* |
|
* If the op is not a special byte code, |
|
* it is a ctrl char tagged to be echoed |
|
* as "^X" (where X is the letter |
|
* representing the control char). |
|
* Note that we must ensure there is |
|
* enough space for the whole ctrl pair. |
|
* |
|
*/ |
|
if (space < 2) { |
|
no_space_left = 1; |
|
break; |
|
} |
|
tty_put_char(tty, '^'); |
|
tty_put_char(tty, op ^ 0100); |
|
ldata->column += 2; |
|
space -= 2; |
|
tail += 2; |
|
} |
|
|
|
if (no_space_left) |
|
break; |
|
} else { |
|
if (O_OPOST(tty)) { |
|
int retval = do_output_char(c, tty, space); |
|
if (retval < 0) |
|
break; |
|
space -= retval; |
|
} else { |
|
if (!space) |
|
break; |
|
tty_put_char(tty, c); |
|
space -= 1; |
|
} |
|
tail += 1; |
|
} |
|
} |
|
|
|
/* If the echo buffer is nearly full (so that the possibility exists |
|
* of echo overrun before the next commit), then discard enough |
|
* data at the tail to prevent a subsequent overrun */ |
|
while (ldata->echo_commit > tail && |
|
ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) { |
|
if (echo_buf(ldata, tail) == ECHO_OP_START) { |
|
if (echo_buf(ldata, tail + 1) == ECHO_OP_ERASE_TAB) |
|
tail += 3; |
|
else |
|
tail += 2; |
|
} else |
|
tail++; |
|
} |
|
|
|
not_yet_stored: |
|
ldata->echo_tail = tail; |
|
return old_space - space; |
|
} |
|
|
|
static void commit_echoes(struct tty_struct *tty) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
size_t nr, old, echoed; |
|
size_t head; |
|
|
|
mutex_lock(&ldata->output_lock); |
|
head = ldata->echo_head; |
|
ldata->echo_mark = head; |
|
old = ldata->echo_commit - ldata->echo_tail; |
|
|
|
/* Process committed echoes if the accumulated # of bytes |
|
* is over the threshold (and try again each time another |
|
* block is accumulated) */ |
|
nr = head - ldata->echo_tail; |
|
if (nr < ECHO_COMMIT_WATERMARK || |
|
(nr % ECHO_BLOCK > old % ECHO_BLOCK)) { |
|
mutex_unlock(&ldata->output_lock); |
|
return; |
|
} |
|
|
|
ldata->echo_commit = head; |
|
echoed = __process_echoes(tty); |
|
mutex_unlock(&ldata->output_lock); |
|
|
|
if (echoed && tty->ops->flush_chars) |
|
tty->ops->flush_chars(tty); |
|
} |
|
|
|
static void process_echoes(struct tty_struct *tty) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
size_t echoed; |
|
|
|
if (ldata->echo_mark == ldata->echo_tail) |
|
return; |
|
|
|
mutex_lock(&ldata->output_lock); |
|
ldata->echo_commit = ldata->echo_mark; |
|
echoed = __process_echoes(tty); |
|
mutex_unlock(&ldata->output_lock); |
|
|
|
if (echoed && tty->ops->flush_chars) |
|
tty->ops->flush_chars(tty); |
|
} |
|
|
|
/* NB: echo_mark and echo_head should be equivalent here */ |
|
static void flush_echoes(struct tty_struct *tty) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
|
|
if ((!L_ECHO(tty) && !L_ECHONL(tty)) || |
|
ldata->echo_commit == ldata->echo_head) |
|
return; |
|
|
|
mutex_lock(&ldata->output_lock); |
|
ldata->echo_commit = ldata->echo_head; |
|
__process_echoes(tty); |
|
mutex_unlock(&ldata->output_lock); |
|
} |
|
|
|
/** |
|
* add_echo_byte - add a byte to the echo buffer |
|
* @c: unicode byte to echo |
|
* @ldata: n_tty data |
|
* |
|
* Add a character or operation byte to the echo buffer. |
|
*/ |
|
|
|
static inline void add_echo_byte(unsigned char c, struct n_tty_data *ldata) |
|
{ |
|
*echo_buf_addr(ldata, ldata->echo_head) = c; |
|
smp_wmb(); /* Matches smp_rmb() in echo_buf(). */ |
|
ldata->echo_head++; |
|
} |
|
|
|
/** |
|
* echo_move_back_col - add operation to move back a column |
|
* @ldata: n_tty data |
|
* |
|
* Add an operation to the echo buffer to move back one column. |
|
*/ |
|
|
|
static void echo_move_back_col(struct n_tty_data *ldata) |
|
{ |
|
add_echo_byte(ECHO_OP_START, ldata); |
|
add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata); |
|
} |
|
|
|
/** |
|
* echo_set_canon_col - add operation to set the canon column |
|
* @ldata: n_tty data |
|
* |
|
* Add an operation to the echo buffer to set the canon column |
|
* to the current column. |
|
*/ |
|
|
|
static void echo_set_canon_col(struct n_tty_data *ldata) |
|
{ |
|
add_echo_byte(ECHO_OP_START, ldata); |
|
add_echo_byte(ECHO_OP_SET_CANON_COL, ldata); |
|
} |
|
|
|
/** |
|
* echo_erase_tab - add operation to erase a tab |
|
* @num_chars: number of character columns already used |
|
* @after_tab: true if num_chars starts after a previous tab |
|
* @ldata: n_tty data |
|
* |
|
* Add an operation to the echo buffer to erase a tab. |
|
* |
|
* Called by the eraser function, which knows how many character |
|
* columns have been used since either a previous tab or the start |
|
* of input. This information will be used later, along with |
|
* canon column (if applicable), to go back the correct number |
|
* of columns. |
|
*/ |
|
|
|
static void echo_erase_tab(unsigned int num_chars, int after_tab, |
|
struct n_tty_data *ldata) |
|
{ |
|
add_echo_byte(ECHO_OP_START, ldata); |
|
add_echo_byte(ECHO_OP_ERASE_TAB, ldata); |
|
|
|
/* We only need to know this modulo 8 (tab spacing) */ |
|
num_chars &= 7; |
|
|
|
/* Set the high bit as a flag if num_chars is after a previous tab */ |
|
if (after_tab) |
|
num_chars |= 0x80; |
|
|
|
add_echo_byte(num_chars, ldata); |
|
} |
|
|
|
/** |
|
* echo_char_raw - echo a character raw |
|
* @c: unicode byte to echo |
|
* @ldata: line disc data |
|
* |
|
* Echo user input back onto the screen. This must be called only when |
|
* L_ECHO(tty) is true. Called from the driver receive_buf path. |
|
* |
|
* This variant does not treat control characters specially. |
|
*/ |
|
|
|
static void echo_char_raw(unsigned char c, struct n_tty_data *ldata) |
|
{ |
|
if (c == ECHO_OP_START) { |
|
add_echo_byte(ECHO_OP_START, ldata); |
|
add_echo_byte(ECHO_OP_START, ldata); |
|
} else { |
|
add_echo_byte(c, ldata); |
|
} |
|
} |
|
|
|
/** |
|
* echo_char - echo a character |
|
* @c: unicode byte to echo |
|
* @tty: terminal device |
|
* |
|
* Echo user input back onto the screen. This must be called only when |
|
* L_ECHO(tty) is true. Called from the driver receive_buf path. |
|
* |
|
* This variant tags control characters to be echoed as "^X" |
|
* (where X is the letter representing the control char). |
|
*/ |
|
|
|
static void echo_char(unsigned char c, struct tty_struct *tty) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
|
|
if (c == ECHO_OP_START) { |
|
add_echo_byte(ECHO_OP_START, ldata); |
|
add_echo_byte(ECHO_OP_START, ldata); |
|
} else { |
|
if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') |
|
add_echo_byte(ECHO_OP_START, ldata); |
|
add_echo_byte(c, ldata); |
|
} |
|
} |
|
|
|
/** |
|
* finish_erasing - complete erase |
|
* @ldata: n_tty data |
|
*/ |
|
|
|
static inline void finish_erasing(struct n_tty_data *ldata) |
|
{ |
|
if (ldata->erasing) { |
|
echo_char_raw('/', ldata); |
|
ldata->erasing = 0; |
|
} |
|
} |
|
|
|
/** |
|
* eraser - handle erase function |
|
* @c: character input |
|
* @tty: terminal device |
|
* |
|
* Perform erase and necessary output when an erase character is |
|
* present in the stream from the driver layer. Handles the complexities |
|
* of UTF-8 multibyte symbols. |
|
* |
|
* n_tty_receive_buf()/producer path: |
|
* caller holds non-exclusive termios_rwsem |
|
*/ |
|
|
|
static void eraser(unsigned char c, struct tty_struct *tty) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
enum { ERASE, WERASE, KILL } kill_type; |
|
size_t head; |
|
size_t cnt; |
|
int seen_alnums; |
|
|
|
if (ldata->read_head == ldata->canon_head) { |
|
/* process_output('\a', tty); */ /* what do you think? */ |
|
return; |
|
} |
|
if (c == ERASE_CHAR(tty)) |
|
kill_type = ERASE; |
|
else if (c == WERASE_CHAR(tty)) |
|
kill_type = WERASE; |
|
else { |
|
if (!L_ECHO(tty)) { |
|
ldata->read_head = ldata->canon_head; |
|
return; |
|
} |
|
if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) { |
|
ldata->read_head = ldata->canon_head; |
|
finish_erasing(ldata); |
|
echo_char(KILL_CHAR(tty), tty); |
|
/* Add a newline if ECHOK is on and ECHOKE is off. */ |
|
if (L_ECHOK(tty)) |
|
echo_char_raw('\n', ldata); |
|
return; |
|
} |
|
kill_type = KILL; |
|
} |
|
|
|
seen_alnums = 0; |
|
while (MASK(ldata->read_head) != MASK(ldata->canon_head)) { |
|
head = ldata->read_head; |
|
|
|
/* erase a single possibly multibyte character */ |
|
do { |
|
head--; |
|
c = read_buf(ldata, head); |
|
} while (is_continuation(c, tty) && |
|
MASK(head) != MASK(ldata->canon_head)); |
|
|
|
/* do not partially erase */ |
|
if (is_continuation(c, tty)) |
|
break; |
|
|
|
if (kill_type == WERASE) { |
|
/* Equivalent to BSD's ALTWERASE. */ |
|
if (isalnum(c) || c == '_') |
|
seen_alnums++; |
|
else if (seen_alnums) |
|
break; |
|
} |
|
cnt = ldata->read_head - head; |
|
ldata->read_head = head; |
|
if (L_ECHO(tty)) { |
|
if (L_ECHOPRT(tty)) { |
|
if (!ldata->erasing) { |
|
echo_char_raw('\\', ldata); |
|
ldata->erasing = 1; |
|
} |
|
/* if cnt > 1, output a multi-byte character */ |
|
echo_char(c, tty); |
|
while (--cnt > 0) { |
|
head++; |
|
echo_char_raw(read_buf(ldata, head), ldata); |
|
echo_move_back_col(ldata); |
|
} |
|
} else if (kill_type == ERASE && !L_ECHOE(tty)) { |
|
echo_char(ERASE_CHAR(tty), tty); |
|
} else if (c == '\t') { |
|
unsigned int num_chars = 0; |
|
int after_tab = 0; |
|
size_t tail = ldata->read_head; |
|
|
|
/* |
|
* Count the columns used for characters |
|
* since the start of input or after a |
|
* previous tab. |
|
* This info is used to go back the correct |
|
* number of columns. |
|
*/ |
|
while (MASK(tail) != MASK(ldata->canon_head)) { |
|
tail--; |
|
c = read_buf(ldata, tail); |
|
if (c == '\t') { |
|
after_tab = 1; |
|
break; |
|
} else if (iscntrl(c)) { |
|
if (L_ECHOCTL(tty)) |
|
num_chars += 2; |
|
} else if (!is_continuation(c, tty)) { |
|
num_chars++; |
|
} |
|
} |
|
echo_erase_tab(num_chars, after_tab, ldata); |
|
} else { |
|
if (iscntrl(c) && L_ECHOCTL(tty)) { |
|
echo_char_raw('\b', ldata); |
|
echo_char_raw(' ', ldata); |
|
echo_char_raw('\b', ldata); |
|
} |
|
if (!iscntrl(c) || L_ECHOCTL(tty)) { |
|
echo_char_raw('\b', ldata); |
|
echo_char_raw(' ', ldata); |
|
echo_char_raw('\b', ldata); |
|
} |
|
} |
|
} |
|
if (kill_type == ERASE) |
|
break; |
|
} |
|
if (ldata->read_head == ldata->canon_head && L_ECHO(tty)) |
|
finish_erasing(ldata); |
|
} |
|
|
|
/** |
|
* isig - handle the ISIG optio |
|
* @sig: signal |
|
* @tty: terminal |
|
* |
|
* Called when a signal is being sent due to terminal input. |
|
* Called from the driver receive_buf path so serialized. |
|
* |
|
* Performs input and output flush if !NOFLSH. In this context, the echo |
|
* buffer is 'output'. The signal is processed first to alert any current |
|
* readers or writers to discontinue and exit their i/o loops. |
|
* |
|
* Locking: ctrl.lock |
|
*/ |
|
|
|
static void __isig(int sig, struct tty_struct *tty) |
|
{ |
|
struct pid *tty_pgrp = tty_get_pgrp(tty); |
|
if (tty_pgrp) { |
|
kill_pgrp(tty_pgrp, sig, 1); |
|
put_pid(tty_pgrp); |
|
} |
|
} |
|
|
|
static void isig(int sig, struct tty_struct *tty) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
|
|
if (L_NOFLSH(tty)) { |
|
/* signal only */ |
|
__isig(sig, tty); |
|
|
|
} else { /* signal and flush */ |
|
up_read(&tty->termios_rwsem); |
|
down_write(&tty->termios_rwsem); |
|
|
|
__isig(sig, tty); |
|
|
|
/* clear echo buffer */ |
|
mutex_lock(&ldata->output_lock); |
|
ldata->echo_head = ldata->echo_tail = 0; |
|
ldata->echo_mark = ldata->echo_commit = 0; |
|
mutex_unlock(&ldata->output_lock); |
|
|
|
/* clear output buffer */ |
|
tty_driver_flush_buffer(tty); |
|
|
|
/* clear input buffer */ |
|
reset_buffer_flags(tty->disc_data); |
|
|
|
/* notify pty master of flush */ |
|
if (tty->link) |
|
n_tty_packet_mode_flush(tty); |
|
|
|
up_write(&tty->termios_rwsem); |
|
down_read(&tty->termios_rwsem); |
|
} |
|
} |
|
|
|
/** |
|
* n_tty_receive_break - handle break |
|
* @tty: terminal |
|
* |
|
* An RS232 break event has been hit in the incoming bitstream. This |
|
* can cause a variety of events depending upon the termios settings. |
|
* |
|
* n_tty_receive_buf()/producer path: |
|
* caller holds non-exclusive termios_rwsem |
|
* |
|
* Note: may get exclusive termios_rwsem if flushing input buffer |
|
*/ |
|
|
|
static void n_tty_receive_break(struct tty_struct *tty) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
|
|
if (I_IGNBRK(tty)) |
|
return; |
|
if (I_BRKINT(tty)) { |
|
isig(SIGINT, tty); |
|
return; |
|
} |
|
if (I_PARMRK(tty)) { |
|
put_tty_queue('\377', ldata); |
|
put_tty_queue('\0', ldata); |
|
} |
|
put_tty_queue('\0', ldata); |
|
} |
|
|
|
/** |
|
* n_tty_receive_overrun - handle overrun reporting |
|
* @tty: terminal |
|
* |
|
* Data arrived faster than we could process it. While the tty |
|
* driver has flagged this the bits that were missed are gone |
|
* forever. |
|
* |
|
* Called from the receive_buf path so single threaded. Does not |
|
* need locking as num_overrun and overrun_time are function |
|
* private. |
|
*/ |
|
|
|
static void n_tty_receive_overrun(struct tty_struct *tty) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
|
|
ldata->num_overrun++; |
|
if (time_after(jiffies, ldata->overrun_time + HZ) || |
|
time_after(ldata->overrun_time, jiffies)) { |
|
tty_warn(tty, "%d input overrun(s)\n", ldata->num_overrun); |
|
ldata->overrun_time = jiffies; |
|
ldata->num_overrun = 0; |
|
} |
|
} |
|
|
|
/** |
|
* n_tty_receive_parity_error - error notifier |
|
* @tty: terminal device |
|
* @c: character |
|
* |
|
* Process a parity error and queue the right data to indicate |
|
* the error case if necessary. |
|
* |
|
* n_tty_receive_buf()/producer path: |
|
* caller holds non-exclusive termios_rwsem |
|
*/ |
|
static void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
|
|
if (I_INPCK(tty)) { |
|
if (I_IGNPAR(tty)) |
|
return; |
|
if (I_PARMRK(tty)) { |
|
put_tty_queue('\377', ldata); |
|
put_tty_queue('\0', ldata); |
|
put_tty_queue(c, ldata); |
|
} else |
|
put_tty_queue('\0', ldata); |
|
} else |
|
put_tty_queue(c, ldata); |
|
} |
|
|
|
static void |
|
n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c) |
|
{ |
|
isig(signal, tty); |
|
if (I_IXON(tty)) |
|
start_tty(tty); |
|
if (L_ECHO(tty)) { |
|
echo_char(c, tty); |
|
commit_echoes(tty); |
|
} else |
|
process_echoes(tty); |
|
} |
|
|
|
/** |
|
* n_tty_receive_char - perform processing |
|
* @tty: terminal device |
|
* @c: character |
|
* |
|
* Process an individual character of input received from the driver. |
|
* This is serialized with respect to itself by the rules for the |
|
* driver above. |
|
* |
|
* n_tty_receive_buf()/producer path: |
|
* caller holds non-exclusive termios_rwsem |
|
* publishes canon_head if canonical mode is active |
|
*/ |
|
static void n_tty_receive_char_special(struct tty_struct *tty, unsigned char c) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
|
|
if (I_IXON(tty)) { |
|
if (c == START_CHAR(tty)) { |
|
start_tty(tty); |
|
process_echoes(tty); |
|
return; |
|
} |
|
if (c == STOP_CHAR(tty)) { |
|
stop_tty(tty); |
|
return; |
|
} |
|
} |
|
|
|
if (L_ISIG(tty)) { |
|
if (c == INTR_CHAR(tty)) { |
|
n_tty_receive_signal_char(tty, SIGINT, c); |
|
return; |
|
} else if (c == QUIT_CHAR(tty)) { |
|
n_tty_receive_signal_char(tty, SIGQUIT, c); |
|
return; |
|
} else if (c == SUSP_CHAR(tty)) { |
|
n_tty_receive_signal_char(tty, SIGTSTP, c); |
|
return; |
|
} |
|
} |
|
|
|
if (tty->flow.stopped && !tty->flow.tco_stopped && I_IXON(tty) && I_IXANY(tty)) { |
|
start_tty(tty); |
|
process_echoes(tty); |
|
} |
|
|
|
if (c == '\r') { |
|
if (I_IGNCR(tty)) |
|
return; |
|
if (I_ICRNL(tty)) |
|
c = '\n'; |
|
} else if (c == '\n' && I_INLCR(tty)) |
|
c = '\r'; |
|
|
|
if (ldata->icanon) { |
|
if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) || |
|
(c == WERASE_CHAR(tty) && L_IEXTEN(tty))) { |
|
eraser(c, tty); |
|
commit_echoes(tty); |
|
return; |
|
} |
|
if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) { |
|
ldata->lnext = 1; |
|
if (L_ECHO(tty)) { |
|
finish_erasing(ldata); |
|
if (L_ECHOCTL(tty)) { |
|
echo_char_raw('^', ldata); |
|
echo_char_raw('\b', ldata); |
|
commit_echoes(tty); |
|
} |
|
} |
|
return; |
|
} |
|
if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && L_IEXTEN(tty)) { |
|
size_t tail = ldata->canon_head; |
|
|
|
finish_erasing(ldata); |
|
echo_char(c, tty); |
|
echo_char_raw('\n', ldata); |
|
while (MASK(tail) != MASK(ldata->read_head)) { |
|
echo_char(read_buf(ldata, tail), tty); |
|
tail++; |
|
} |
|
commit_echoes(tty); |
|
return; |
|
} |
|
if (c == '\n') { |
|
if (L_ECHO(tty) || L_ECHONL(tty)) { |
|
echo_char_raw('\n', ldata); |
|
commit_echoes(tty); |
|
} |
|
goto handle_newline; |
|
} |
|
if (c == EOF_CHAR(tty)) { |
|
c = __DISABLED_CHAR; |
|
goto handle_newline; |
|
} |
|
if ((c == EOL_CHAR(tty)) || |
|
(c == EOL2_CHAR(tty) && L_IEXTEN(tty))) { |
|
/* |
|
* XXX are EOL_CHAR and EOL2_CHAR echoed?!? |
|
*/ |
|
if (L_ECHO(tty)) { |
|
/* Record the column of first canon char. */ |
|
if (ldata->canon_head == ldata->read_head) |
|
echo_set_canon_col(ldata); |
|
echo_char(c, tty); |
|
commit_echoes(tty); |
|
} |
|
/* |
|
* XXX does PARMRK doubling happen for |
|
* EOL_CHAR and EOL2_CHAR? |
|
*/ |
|
if (c == (unsigned char) '\377' && I_PARMRK(tty)) |
|
put_tty_queue(c, ldata); |
|
|
|
handle_newline: |
|
set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags); |
|
put_tty_queue(c, ldata); |
|
smp_store_release(&ldata->canon_head, ldata->read_head); |
|
kill_fasync(&tty->fasync, SIGIO, POLL_IN); |
|
wake_up_interruptible_poll(&tty->read_wait, EPOLLIN); |
|
return; |
|
} |
|
} |
|
|
|
if (L_ECHO(tty)) { |
|
finish_erasing(ldata); |
|
if (c == '\n') |
|
echo_char_raw('\n', ldata); |
|
else { |
|
/* Record the column of first canon char. */ |
|
if (ldata->canon_head == ldata->read_head) |
|
echo_set_canon_col(ldata); |
|
echo_char(c, tty); |
|
} |
|
commit_echoes(tty); |
|
} |
|
|
|
/* PARMRK doubling check */ |
|
if (c == (unsigned char) '\377' && I_PARMRK(tty)) |
|
put_tty_queue(c, ldata); |
|
|
|
put_tty_queue(c, ldata); |
|
} |
|
|
|
static void n_tty_receive_char(struct tty_struct *tty, unsigned char c) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
|
|
if (tty->flow.stopped && !tty->flow.tco_stopped && I_IXON(tty) && I_IXANY(tty)) { |
|
start_tty(tty); |
|
process_echoes(tty); |
|
} |
|
if (L_ECHO(tty)) { |
|
finish_erasing(ldata); |
|
/* Record the column of first canon char. */ |
|
if (ldata->canon_head == ldata->read_head) |
|
echo_set_canon_col(ldata); |
|
echo_char(c, tty); |
|
commit_echoes(tty); |
|
} |
|
/* PARMRK doubling check */ |
|
if (c == (unsigned char) '\377' && I_PARMRK(tty)) |
|
put_tty_queue(c, ldata); |
|
put_tty_queue(c, ldata); |
|
} |
|
|
|
static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c) |
|
{ |
|
if (I_ISTRIP(tty)) |
|
c &= 0x7f; |
|
if (I_IUCLC(tty) && L_IEXTEN(tty)) |
|
c = tolower(c); |
|
|
|
if (I_IXON(tty)) { |
|
if (c == STOP_CHAR(tty)) |
|
stop_tty(tty); |
|
else if (c == START_CHAR(tty) || |
|
(tty->flow.stopped && !tty->flow.tco_stopped && I_IXANY(tty) && |
|
c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && |
|
c != SUSP_CHAR(tty))) { |
|
start_tty(tty); |
|
process_echoes(tty); |
|
} |
|
} |
|
} |
|
|
|
static void |
|
n_tty_receive_char_flagged(struct tty_struct *tty, unsigned char c, char flag) |
|
{ |
|
switch (flag) { |
|
case TTY_BREAK: |
|
n_tty_receive_break(tty); |
|
break; |
|
case TTY_PARITY: |
|
case TTY_FRAME: |
|
n_tty_receive_parity_error(tty, c); |
|
break; |
|
case TTY_OVERRUN: |
|
n_tty_receive_overrun(tty); |
|
break; |
|
default: |
|
tty_err(tty, "unknown flag %d\n", flag); |
|
break; |
|
} |
|
} |
|
|
|
static void |
|
n_tty_receive_char_lnext(struct tty_struct *tty, unsigned char c, char flag) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
|
|
ldata->lnext = 0; |
|
if (likely(flag == TTY_NORMAL)) { |
|
if (I_ISTRIP(tty)) |
|
c &= 0x7f; |
|
if (I_IUCLC(tty) && L_IEXTEN(tty)) |
|
c = tolower(c); |
|
n_tty_receive_char(tty, c); |
|
} else |
|
n_tty_receive_char_flagged(tty, c, flag); |
|
} |
|
|
|
static void |
|
n_tty_receive_buf_real_raw(struct tty_struct *tty, const unsigned char *cp, |
|
const char *fp, int count) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
size_t n, head; |
|
|
|
head = ldata->read_head & (N_TTY_BUF_SIZE - 1); |
|
n = min_t(size_t, count, N_TTY_BUF_SIZE - head); |
|
memcpy(read_buf_addr(ldata, head), cp, n); |
|
ldata->read_head += n; |
|
cp += n; |
|
count -= n; |
|
|
|
head = ldata->read_head & (N_TTY_BUF_SIZE - 1); |
|
n = min_t(size_t, count, N_TTY_BUF_SIZE - head); |
|
memcpy(read_buf_addr(ldata, head), cp, n); |
|
ldata->read_head += n; |
|
} |
|
|
|
static void |
|
n_tty_receive_buf_raw(struct tty_struct *tty, const unsigned char *cp, |
|
const char *fp, int count) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
char flag = TTY_NORMAL; |
|
|
|
while (count--) { |
|
if (fp) |
|
flag = *fp++; |
|
if (likely(flag == TTY_NORMAL)) |
|
put_tty_queue(*cp++, ldata); |
|
else |
|
n_tty_receive_char_flagged(tty, *cp++, flag); |
|
} |
|
} |
|
|
|
static void |
|
n_tty_receive_buf_closing(struct tty_struct *tty, const unsigned char *cp, |
|
const char *fp, int count) |
|
{ |
|
char flag = TTY_NORMAL; |
|
|
|
while (count--) { |
|
if (fp) |
|
flag = *fp++; |
|
if (likely(flag == TTY_NORMAL)) |
|
n_tty_receive_char_closing(tty, *cp++); |
|
} |
|
} |
|
|
|
static void n_tty_receive_buf_standard(struct tty_struct *tty, |
|
const unsigned char *cp, const char *fp, int count) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
char flag = TTY_NORMAL; |
|
|
|
while (count--) { |
|
unsigned char c = *cp++; |
|
|
|
if (fp) |
|
flag = *fp++; |
|
|
|
if (ldata->lnext) { |
|
n_tty_receive_char_lnext(tty, c, flag); |
|
continue; |
|
} |
|
|
|
if (unlikely(flag != TTY_NORMAL)) { |
|
n_tty_receive_char_flagged(tty, c, flag); |
|
continue; |
|
} |
|
|
|
if (I_ISTRIP(tty)) |
|
c &= 0x7f; |
|
if (I_IUCLC(tty) && L_IEXTEN(tty)) |
|
c = tolower(c); |
|
if (L_EXTPROC(tty)) { |
|
put_tty_queue(c, ldata); |
|
continue; |
|
} |
|
|
|
if (test_bit(c, ldata->char_map)) |
|
n_tty_receive_char_special(tty, c); |
|
else |
|
n_tty_receive_char(tty, c); |
|
} |
|
} |
|
|
|
static void __receive_buf(struct tty_struct *tty, const unsigned char *cp, |
|
const char *fp, int count) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
bool preops = I_ISTRIP(tty) || (I_IUCLC(tty) && L_IEXTEN(tty)); |
|
|
|
if (ldata->real_raw) |
|
n_tty_receive_buf_real_raw(tty, cp, fp, count); |
|
else if (ldata->raw || (L_EXTPROC(tty) && !preops)) |
|
n_tty_receive_buf_raw(tty, cp, fp, count); |
|
else if (tty->closing && !L_EXTPROC(tty)) |
|
n_tty_receive_buf_closing(tty, cp, fp, count); |
|
else { |
|
n_tty_receive_buf_standard(tty, cp, fp, count); |
|
|
|
flush_echoes(tty); |
|
if (tty->ops->flush_chars) |
|
tty->ops->flush_chars(tty); |
|
} |
|
|
|
if (ldata->icanon && !L_EXTPROC(tty)) |
|
return; |
|
|
|
/* publish read_head to consumer */ |
|
smp_store_release(&ldata->commit_head, ldata->read_head); |
|
|
|
if (read_cnt(ldata)) { |
|
kill_fasync(&tty->fasync, SIGIO, POLL_IN); |
|
wake_up_interruptible_poll(&tty->read_wait, EPOLLIN); |
|
} |
|
} |
|
|
|
/** |
|
* n_tty_receive_buf_common - process input |
|
* @tty: device to receive input |
|
* @cp: input chars |
|
* @fp: flags for each char (if NULL, all chars are TTY_NORMAL) |
|
* @count: number of input chars in @cp |
|
* @flow: enable flow control |
|
* |
|
* Called by the terminal driver when a block of characters has |
|
* been received. This function must be called from soft contexts |
|
* not from interrupt context. The driver is responsible for making |
|
* calls one at a time and in order (or using flush_to_ldisc) |
|
* |
|
* Returns the # of input chars from @cp which were processed. |
|
* |
|
* In canonical mode, the maximum line length is 4096 chars (including |
|
* the line termination char); lines longer than 4096 chars are |
|
* truncated. After 4095 chars, input data is still processed but |
|
* not stored. Overflow processing ensures the tty can always |
|
* receive more input until at least one line can be read. |
|
* |
|
* In non-canonical mode, the read buffer will only accept 4095 chars; |
|
* this provides the necessary space for a newline char if the input |
|
* mode is switched to canonical. |
|
* |
|
* Note it is possible for the read buffer to _contain_ 4096 chars |
|
* in non-canonical mode: the read buffer could already contain the |
|
* maximum canon line of 4096 chars when the mode is switched to |
|
* non-canonical. |
|
* |
|
* n_tty_receive_buf()/producer path: |
|
* claims non-exclusive termios_rwsem |
|
* publishes commit_head or canon_head |
|
*/ |
|
static int |
|
n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp, |
|
const char *fp, int count, int flow) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
int room, n, rcvd = 0, overflow; |
|
|
|
down_read(&tty->termios_rwsem); |
|
|
|
do { |
|
/* |
|
* When PARMRK is set, each input char may take up to 3 chars |
|
* in the read buf; reduce the buffer space avail by 3x |
|
* |
|
* If we are doing input canonicalization, and there are no |
|
* pending newlines, let characters through without limit, so |
|
* that erase characters will be handled. Other excess |
|
* characters will be beeped. |
|
* |
|
* paired with store in *_copy_from_read_buf() -- guarantees |
|
* the consumer has loaded the data in read_buf up to the new |
|
* read_tail (so this producer will not overwrite unread data) |
|
*/ |
|
size_t tail = smp_load_acquire(&ldata->read_tail); |
|
|
|
room = N_TTY_BUF_SIZE - (ldata->read_head - tail); |
|
if (I_PARMRK(tty)) |
|
room = (room + 2) / 3; |
|
room--; |
|
if (room <= 0) { |
|
overflow = ldata->icanon && ldata->canon_head == tail; |
|
if (overflow && room < 0) |
|
ldata->read_head--; |
|
room = overflow; |
|
ldata->no_room = flow && !room; |
|
} else |
|
overflow = 0; |
|
|
|
n = min(count, room); |
|
if (!n) |
|
break; |
|
|
|
/* ignore parity errors if handling overflow */ |
|
if (!overflow || !fp || *fp != TTY_PARITY) |
|
__receive_buf(tty, cp, fp, n); |
|
|
|
cp += n; |
|
if (fp) |
|
fp += n; |
|
count -= n; |
|
rcvd += n; |
|
} while (!test_bit(TTY_LDISC_CHANGING, &tty->flags)); |
|
|
|
tty->receive_room = room; |
|
|
|
/* Unthrottle if handling overflow on pty */ |
|
if (tty->driver->type == TTY_DRIVER_TYPE_PTY) { |
|
if (overflow) { |
|
tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE); |
|
tty_unthrottle_safe(tty); |
|
__tty_set_flow_change(tty, 0); |
|
} |
|
} else |
|
n_tty_check_throttle(tty); |
|
|
|
up_read(&tty->termios_rwsem); |
|
|
|
return rcvd; |
|
} |
|
|
|
static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp, |
|
const char *fp, int count) |
|
{ |
|
n_tty_receive_buf_common(tty, cp, fp, count, 0); |
|
} |
|
|
|
static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp, |
|
const char *fp, int count) |
|
{ |
|
return n_tty_receive_buf_common(tty, cp, fp, count, 1); |
|
} |
|
|
|
/** |
|
* n_tty_set_termios - termios data changed |
|
* @tty: terminal |
|
* @old: previous data |
|
* |
|
* Called by the tty layer when the user changes termios flags so |
|
* that the line discipline can plan ahead. This function cannot sleep |
|
* and is protected from re-entry by the tty layer. The user is |
|
* guaranteed that this function will not be re-entered or in progress |
|
* when the ldisc is closed. |
|
* |
|
* Locking: Caller holds tty->termios_rwsem |
|
*/ |
|
|
|
static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
|
|
if (!old || (old->c_lflag ^ tty->termios.c_lflag) & (ICANON | EXTPROC)) { |
|
bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE); |
|
ldata->line_start = ldata->read_tail; |
|
if (!L_ICANON(tty) || !read_cnt(ldata)) { |
|
ldata->canon_head = ldata->read_tail; |
|
ldata->push = 0; |
|
} else { |
|
set_bit((ldata->read_head - 1) & (N_TTY_BUF_SIZE - 1), |
|
ldata->read_flags); |
|
ldata->canon_head = ldata->read_head; |
|
ldata->push = 1; |
|
} |
|
ldata->commit_head = ldata->read_head; |
|
ldata->erasing = 0; |
|
ldata->lnext = 0; |
|
} |
|
|
|
ldata->icanon = (L_ICANON(tty) != 0); |
|
|
|
if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) || |
|
I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) || |
|
I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) || |
|
I_PARMRK(tty)) { |
|
bitmap_zero(ldata->char_map, 256); |
|
|
|
if (I_IGNCR(tty) || I_ICRNL(tty)) |
|
set_bit('\r', ldata->char_map); |
|
if (I_INLCR(tty)) |
|
set_bit('\n', ldata->char_map); |
|
|
|
if (L_ICANON(tty)) { |
|
set_bit(ERASE_CHAR(tty), ldata->char_map); |
|
set_bit(KILL_CHAR(tty), ldata->char_map); |
|
set_bit(EOF_CHAR(tty), ldata->char_map); |
|
set_bit('\n', ldata->char_map); |
|
set_bit(EOL_CHAR(tty), ldata->char_map); |
|
if (L_IEXTEN(tty)) { |
|
set_bit(WERASE_CHAR(tty), ldata->char_map); |
|
set_bit(LNEXT_CHAR(tty), ldata->char_map); |
|
set_bit(EOL2_CHAR(tty), ldata->char_map); |
|
if (L_ECHO(tty)) |
|
set_bit(REPRINT_CHAR(tty), |
|
ldata->char_map); |
|
} |
|
} |
|
if (I_IXON(tty)) { |
|
set_bit(START_CHAR(tty), ldata->char_map); |
|
set_bit(STOP_CHAR(tty), ldata->char_map); |
|
} |
|
if (L_ISIG(tty)) { |
|
set_bit(INTR_CHAR(tty), ldata->char_map); |
|
set_bit(QUIT_CHAR(tty), ldata->char_map); |
|
set_bit(SUSP_CHAR(tty), ldata->char_map); |
|
} |
|
clear_bit(__DISABLED_CHAR, ldata->char_map); |
|
ldata->raw = 0; |
|
ldata->real_raw = 0; |
|
} else { |
|
ldata->raw = 1; |
|
if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) && |
|
(I_IGNPAR(tty) || !I_INPCK(tty)) && |
|
(tty->driver->flags & TTY_DRIVER_REAL_RAW)) |
|
ldata->real_raw = 1; |
|
else |
|
ldata->real_raw = 0; |
|
} |
|
/* |
|
* Fix tty hang when I_IXON(tty) is cleared, but the tty |
|
* been stopped by STOP_CHAR(tty) before it. |
|
*/ |
|
if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow.tco_stopped) { |
|
start_tty(tty); |
|
process_echoes(tty); |
|
} |
|
|
|
/* The termios change make the tty ready for I/O */ |
|
wake_up_interruptible(&tty->write_wait); |
|
wake_up_interruptible(&tty->read_wait); |
|
} |
|
|
|
/** |
|
* n_tty_close - close the ldisc for this tty |
|
* @tty: device |
|
* |
|
* Called from the terminal layer when this line discipline is |
|
* being shut down, either because of a close or becsuse of a |
|
* discipline change. The function will not be called while other |
|
* ldisc methods are in progress. |
|
*/ |
|
|
|
static void n_tty_close(struct tty_struct *tty) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
|
|
if (tty->link) |
|
n_tty_packet_mode_flush(tty); |
|
|
|
down_write(&tty->termios_rwsem); |
|
vfree(ldata); |
|
tty->disc_data = NULL; |
|
up_write(&tty->termios_rwsem); |
|
} |
|
|
|
/** |
|
* n_tty_open - open an ldisc |
|
* @tty: terminal to open |
|
* |
|
* Called when this line discipline is being attached to the |
|
* terminal device. Can sleep. Called serialized so that no |
|
* other events will occur in parallel. No further open will occur |
|
* until a close. |
|
*/ |
|
|
|
static int n_tty_open(struct tty_struct *tty) |
|
{ |
|
struct n_tty_data *ldata; |
|
|
|
/* Currently a malloc failure here can panic */ |
|
ldata = vzalloc(sizeof(*ldata)); |
|
if (!ldata) |
|
return -ENOMEM; |
|
|
|
ldata->overrun_time = jiffies; |
|
mutex_init(&ldata->atomic_read_lock); |
|
mutex_init(&ldata->output_lock); |
|
|
|
tty->disc_data = ldata; |
|
tty->closing = 0; |
|
/* indicate buffer work may resume */ |
|
clear_bit(TTY_LDISC_HALTED, &tty->flags); |
|
n_tty_set_termios(tty, NULL); |
|
tty_unthrottle(tty); |
|
return 0; |
|
} |
|
|
|
static inline int input_available_p(struct tty_struct *tty, int poll) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
int amt = poll && !TIME_CHAR(tty) && MIN_CHAR(tty) ? MIN_CHAR(tty) : 1; |
|
|
|
if (ldata->icanon && !L_EXTPROC(tty)) |
|
return ldata->canon_head != ldata->read_tail; |
|
else |
|
return ldata->commit_head - ldata->read_tail >= amt; |
|
} |
|
|
|
/** |
|
* copy_from_read_buf - copy read data directly |
|
* @tty: terminal device |
|
* @kbp: data |
|
* @nr: size of data |
|
* |
|
* Helper function to speed up n_tty_read. It is only called when |
|
* ICANON is off; it copies characters straight from the tty queue. |
|
* |
|
* Called under the ldata->atomic_read_lock sem |
|
* |
|
* Returns true if it successfully copied data, but there is still |
|
* more data to be had. |
|
* |
|
* n_tty_read()/consumer path: |
|
* caller holds non-exclusive termios_rwsem |
|
* read_tail published |
|
*/ |
|
|
|
static bool copy_from_read_buf(struct tty_struct *tty, |
|
unsigned char **kbp, |
|
size_t *nr) |
|
|
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
size_t n; |
|
bool is_eof; |
|
size_t head = smp_load_acquire(&ldata->commit_head); |
|
size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1); |
|
|
|
n = min(head - ldata->read_tail, N_TTY_BUF_SIZE - tail); |
|
n = min(*nr, n); |
|
if (n) { |
|
unsigned char *from = read_buf_addr(ldata, tail); |
|
memcpy(*kbp, from, n); |
|
is_eof = n == 1 && *from == EOF_CHAR(tty); |
|
tty_audit_add_data(tty, from, n); |
|
zero_buffer(tty, from, n); |
|
smp_store_release(&ldata->read_tail, ldata->read_tail + n); |
|
/* Turn single EOF into zero-length read */ |
|
if (L_EXTPROC(tty) && ldata->icanon && is_eof && |
|
(head == ldata->read_tail)) |
|
return false; |
|
*kbp += n; |
|
*nr -= n; |
|
|
|
/* If we have more to copy, let the caller know */ |
|
return head != ldata->read_tail; |
|
} |
|
return false; |
|
} |
|
|
|
/** |
|
* canon_copy_from_read_buf - copy read data in canonical mode |
|
* @tty: terminal device |
|
* @kbp: data |
|
* @nr: size of data |
|
* |
|
* Helper function for n_tty_read. It is only called when ICANON is on; |
|
* it copies one line of input up to and including the line-delimiting |
|
* character into the result buffer. |
|
* |
|
* NB: When termios is changed from non-canonical to canonical mode and |
|
* the read buffer contains data, n_tty_set_termios() simulates an EOF |
|
* push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer. |
|
* This causes data already processed as input to be immediately available |
|
* as input although a newline has not been received. |
|
* |
|
* Called under the atomic_read_lock mutex |
|
* |
|
* n_tty_read()/consumer path: |
|
* caller holds non-exclusive termios_rwsem |
|
* read_tail published |
|
*/ |
|
|
|
static bool canon_copy_from_read_buf(struct tty_struct *tty, |
|
unsigned char **kbp, |
|
size_t *nr) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
size_t n, size, more, c; |
|
size_t eol; |
|
size_t tail, canon_head; |
|
int found = 0; |
|
|
|
/* N.B. avoid overrun if nr == 0 */ |
|
if (!*nr) |
|
return false; |
|
|
|
canon_head = smp_load_acquire(&ldata->canon_head); |
|
n = min(*nr + 1, canon_head - ldata->read_tail); |
|
|
|
tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1); |
|
size = min_t(size_t, tail + n, N_TTY_BUF_SIZE); |
|
|
|
n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n", |
|
__func__, *nr, tail, n, size); |
|
|
|
eol = find_next_bit(ldata->read_flags, size, tail); |
|
more = n - (size - tail); |
|
if (eol == N_TTY_BUF_SIZE && more) { |
|
/* scan wrapped without finding set bit */ |
|
eol = find_next_bit(ldata->read_flags, more, 0); |
|
found = eol != more; |
|
} else |
|
found = eol != size; |
|
|
|
n = eol - tail; |
|
if (n > N_TTY_BUF_SIZE) |
|
n += N_TTY_BUF_SIZE; |
|
c = n + found; |
|
|
|
if (!found || read_buf(ldata, eol) != __DISABLED_CHAR) { |
|
c = min(*nr, c); |
|
n = c; |
|
} |
|
|
|
n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu tail:%zu more:%zu\n", |
|
__func__, eol, found, n, c, tail, more); |
|
|
|
tty_copy(tty, *kbp, tail, n); |
|
*kbp += n; |
|
*nr -= n; |
|
|
|
if (found) |
|
clear_bit(eol, ldata->read_flags); |
|
smp_store_release(&ldata->read_tail, ldata->read_tail + c); |
|
|
|
if (found) { |
|
if (!ldata->push) |
|
ldata->line_start = ldata->read_tail; |
|
else |
|
ldata->push = 0; |
|
tty_audit_push(); |
|
return false; |
|
} |
|
|
|
/* No EOL found - do a continuation retry if there is more data */ |
|
return ldata->read_tail != canon_head; |
|
} |
|
|
|
/** |
|
* job_control - check job control |
|
* @tty: tty |
|
* @file: file handle |
|
* |
|
* Perform job control management checks on this file/tty descriptor |
|
* and if appropriate send any needed signals and return a negative |
|
* error code if action should be taken. |
|
* |
|
* Locking: redirected write test is safe |
|
* current->signal->tty check is safe |
|
* ctrl.lock to safely reference tty->ctrl.pgrp |
|
*/ |
|
|
|
static int job_control(struct tty_struct *tty, struct file *file) |
|
{ |
|
/* Job control check -- must be done at start and after |
|
every sleep (POSIX.1 7.1.1.4). */ |
|
/* NOTE: not yet done after every sleep pending a thorough |
|
check of the logic of this change. -- jlc */ |
|
/* don't stop on /dev/console */ |
|
if (file->f_op->write_iter == redirected_tty_write) |
|
return 0; |
|
|
|
return __tty_check_change(tty, SIGTTIN); |
|
} |
|
|
|
|
|
/** |
|
* n_tty_read - read function for tty |
|
* @tty: tty device |
|
* @file: file object |
|
* @buf: userspace buffer pointer |
|
* @nr: size of I/O |
|
* |
|
* Perform reads for the line discipline. We are guaranteed that the |
|
* line discipline will not be closed under us but we may get multiple |
|
* parallel readers and must handle this ourselves. We may also get |
|
* a hangup. Always called in user context, may sleep. |
|
* |
|
* This code must be sure never to sleep through a hangup. |
|
* |
|
* n_tty_read()/consumer path: |
|
* claims non-exclusive termios_rwsem |
|
* publishes read_tail |
|
*/ |
|
|
|
static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, |
|
unsigned char *kbuf, size_t nr, |
|
void **cookie, unsigned long offset) |
|
{ |
|
struct n_tty_data *ldata = tty->disc_data; |
|
unsigned char *kb = kbuf; |
|
DEFINE_WAIT_FUNC(wait, woken_wake_function); |
|
int c; |
|
int minimum, time; |
|
ssize_t retval = 0; |
|
long timeout; |
|
bool packet; |
|
size_t tail; |
|
|
|
/* |
|
* Is this a continuation of a read started earler? |
|
* |
|
* If so, we still hold the atomic_read_lock and the |
|
* termios_rwsem, and can just continue to copy data. |
|
*/ |
|
if (*cookie) { |
|
if (ldata->icanon && !L_EXTPROC(tty)) { |
|
if (canon_copy_from_read_buf(tty, &kb, &nr)) |
|
return kb - kbuf; |
|
} else { |
|
if (copy_from_read_buf(tty, &kb, &nr)) |
|
return kb - kbuf; |
|
} |
|
|
|
/* No more data - release locks and stop retries */ |
|
n_tty_kick_worker(tty); |
|
n_tty_check_unthrottle(tty); |
|
up_read(&tty->termios_rwsem); |
|
mutex_unlock(&ldata->atomic_read_lock); |
|
*cookie = NULL; |
|
return kb - kbuf; |
|
} |
|
|
|
c = job_control(tty, file); |
|
if (c < 0) |
|
return c; |
|
|
|
/* |
|
* Internal serialization of reads. |
|
*/ |
|
if (file->f_flags & O_NONBLOCK) { |
|
if (!mutex_trylock(&ldata->atomic_read_lock)) |
|
return -EAGAIN; |
|
} else { |
|
if (mutex_lock_interruptible(&ldata->atomic_read_lock)) |
|
return -ERESTARTSYS; |
|
} |
|
|
|
down_read(&tty->termios_rwsem); |
|
|
|
minimum = time = 0; |
|
timeout = MAX_SCHEDULE_TIMEOUT; |
|
if (!ldata->icanon) { |
|
minimum = MIN_CHAR(tty); |
|
if (minimum) { |
|
time = (HZ / 10) * TIME_CHAR(tty); |
|
} else { |
|
timeout = (HZ / 10) * TIME_CHAR(tty); |
|
minimum = 1; |
|
} |
|
} |
|
|
|
packet = tty->ctrl.packet; |
|
tail = ldata->read_tail; |
|
|
|
add_wait_queue(&tty->read_wait, &wait); |
|
while (nr) { |
|
/* First test for status change. */ |
|
if (packet && tty->link->ctrl.pktstatus) { |
|
unsigned char cs; |
|
if (kb != kbuf) |
|
break; |
|
spin_lock_irq(&tty->link->ctrl.lock); |
|
cs = tty->link->ctrl.pktstatus; |
|
tty->link->ctrl.pktstatus = 0; |
|
spin_unlock_irq(&tty->link->ctrl.lock); |
|
*kb++ = cs; |
|
nr--; |
|
break; |
|
} |
|
|
|
if (!input_available_p(tty, 0)) { |
|
up_read(&tty->termios_rwsem); |
|
tty_buffer_flush_work(tty->port); |
|
down_read(&tty->termios_rwsem); |
|
if (!input_available_p(tty, 0)) { |
|
if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { |
|
retval = -EIO; |
|
break; |
|
} |
|
if (tty_hung_up_p(file)) |
|
break; |
|
/* |
|
* Abort readers for ttys which never actually |
|
* get hung up. See __tty_hangup(). |
|
*/ |
|
if (test_bit(TTY_HUPPING, &tty->flags)) |
|
break; |
|
if (!timeout) |
|
break; |
|
if (tty_io_nonblock(tty, file)) { |
|
retval = -EAGAIN; |
|
break; |
|
} |
|
if (signal_pending(current)) { |
|
retval = -ERESTARTSYS; |
|
break; |
|
} |
|
up_read(&tty->termios_rwsem); |
|
|
|
timeout = wait_woken(&wait, TASK_INTERRUPTIBLE, |
|
timeout); |
|
|
|
down_read(&tty->termios_rwsem); |
|
continue; |
|
} |
|
} |
|
|
|
if (ldata->icanon && !L_EXTPROC(tty)) { |
|
if (canon_copy_from_read_buf(tty, &kb, &nr)) |
|
goto more_to_be_read; |
|
} else { |
|
/* Deal with packet mode. */ |
|
if (packet && kb == kbuf) { |
|
*kb++ = TIOCPKT_DATA; |
|
nr--; |
|
} |
|
|
|
/* |
|
* Copy data, and if there is more to be had |
|
* and we have nothing more to wait for, then |
|
* let's mark us for retries. |
|
* |
|
* NOTE! We return here with both the termios_sem |
|
* and atomic_read_lock still held, the retries |
|
* will release them when done. |
|
*/ |
|
if (copy_from_read_buf(tty, &kb, &nr) && kb - kbuf >= minimum) { |
|
more_to_be_read: |
|
remove_wait_queue(&tty->read_wait, &wait); |
|
*cookie = cookie; |
|
return kb - kbuf; |
|
} |
|
} |
|
|
|
n_tty_check_unthrottle(tty); |
|
|
|
if (kb - kbuf >= minimum) |
|
break; |
|
if (time) |
|
timeout = time; |
|
} |
|
if (tail != ldata->read_tail) |
|
n_tty_kick_worker(tty); |
|
up_read(&tty->termios_rwsem); |
|
|
|
remove_wait_queue(&tty->read_wait, &wait); |
|
mutex_unlock(&ldata->atomic_read_lock); |
|
|
|
if (kb - kbuf) |
|
retval = kb - kbuf; |
|
|
|
return retval; |
|
} |
|
|
|
/** |
|
* n_tty_write - write function for tty |
|
* @tty: tty device |
|
* @file: file object |
|
* @buf: userspace buffer pointer |
|
* @nr: size of I/O |
|
* |
|
* Write function of the terminal device. This is serialized with |
|
* respect to other write callers but not to termios changes, reads |
|
* and other such events. Since the receive code will echo characters, |
|
* thus calling driver write methods, the output_lock is used in |
|
* the output processing functions called here as well as in the |
|
* echo processing function to protect the column state and space |
|
* left in the buffer. |
|
* |
|
* This code must be sure never to sleep through a hangup. |
|
* |
|
* Locking: output_lock to protect column state and space left |
|
* (note that the process_output*() functions take this |
|
* lock themselves) |
|
*/ |
|
|
|
static ssize_t n_tty_write(struct tty_struct *tty, struct file *file, |
|
const unsigned char *buf, size_t nr) |
|
{ |
|
const unsigned char *b = buf; |
|
DEFINE_WAIT_FUNC(wait, woken_wake_function); |
|
int c; |
|
ssize_t retval = 0; |
|
|
|
/* Job control check -- must be done at start (POSIX.1 7.1.1.4). */ |
|
if (L_TOSTOP(tty) && file->f_op->write_iter != redirected_tty_write) { |
|
retval = tty_check_change(tty); |
|
if (retval) |
|
return retval; |
|
} |
|
|
|
down_read(&tty->termios_rwsem); |
|
|
|
/* Write out any echoed characters that are still pending */ |
|
process_echoes(tty); |
|
|
|
add_wait_queue(&tty->write_wait, &wait); |
|
while (1) { |
|
if (signal_pending(current)) { |
|
retval = -ERESTARTSYS; |
|
break; |
|
} |
|
if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) { |
|
retval = -EIO; |
|
break; |
|
} |
|
if (O_OPOST(tty)) { |
|
while (nr > 0) { |
|
ssize_t num = process_output_block(tty, b, nr); |
|
if (num < 0) { |
|
if (num == -EAGAIN) |
|
break; |
|
retval = num; |
|
goto break_out; |
|
} |
|
b += num; |
|
nr -= num; |
|
if (nr == 0) |
|
break; |
|
c = *b; |
|
if (process_output(c, tty) < 0) |
|
break; |
|
b++; nr--; |
|
} |
|
if (tty->ops->flush_chars) |
|
tty->ops->flush_chars(tty); |
|
} else { |
|
struct n_tty_data *ldata = tty->disc_data; |
|
|
|
while (nr > 0) { |
|
mutex_lock(&ldata->output_lock); |
|
c = tty->ops->write(tty, b, nr); |
|
mutex_unlock(&ldata->output_lock); |
|
if (c < 0) { |
|
retval = c; |
|
goto break_out; |
|
} |
|
if (!c) |
|
break; |
|
b += c; |
|
nr -= c; |
|
} |
|
} |
|
if (!nr) |
|
break; |
|
if (tty_io_nonblock(tty, file)) { |
|
retval = -EAGAIN; |
|
break; |
|
} |
|
up_read(&tty->termios_rwsem); |
|
|
|
wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); |
|
|
|
down_read(&tty->termios_rwsem); |
|
} |
|
break_out: |
|
remove_wait_queue(&tty->write_wait, &wait); |
|
if (nr && tty->fasync) |
|
set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
|
up_read(&tty->termios_rwsem); |
|
return (b - buf) ? b - buf : retval; |
|
} |
|
|
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/** |
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* n_tty_poll - poll method for N_TTY |
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* @tty: terminal device |
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* @file: file accessing it |
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* @wait: poll table |
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* |
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* Called when the line discipline is asked to poll() for data or |
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* for special events. This code is not serialized with respect to |
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* other events save open/close. |
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* |
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* This code must be sure never to sleep through a hangup. |
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* Called without the kernel lock held - fine |
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*/ |
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static __poll_t n_tty_poll(struct tty_struct *tty, struct file *file, |
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poll_table *wait) |
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{ |
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__poll_t mask = 0; |
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poll_wait(file, &tty->read_wait, wait); |
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poll_wait(file, &tty->write_wait, wait); |
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if (input_available_p(tty, 1)) |
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mask |= EPOLLIN | EPOLLRDNORM; |
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else { |
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tty_buffer_flush_work(tty->port); |
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if (input_available_p(tty, 1)) |
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mask |= EPOLLIN | EPOLLRDNORM; |
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} |
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if (tty->ctrl.packet && tty->link->ctrl.pktstatus) |
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mask |= EPOLLPRI | EPOLLIN | EPOLLRDNORM; |
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if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) |
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mask |= EPOLLHUP; |
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if (tty_hung_up_p(file)) |
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mask |= EPOLLHUP; |
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if (tty->ops->write && !tty_is_writelocked(tty) && |
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tty_chars_in_buffer(tty) < WAKEUP_CHARS && |
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tty_write_room(tty) > 0) |
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mask |= EPOLLOUT | EPOLLWRNORM; |
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return mask; |
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} |
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static unsigned long inq_canon(struct n_tty_data *ldata) |
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{ |
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size_t nr, head, tail; |
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if (ldata->canon_head == ldata->read_tail) |
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return 0; |
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head = ldata->canon_head; |
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tail = ldata->read_tail; |
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nr = head - tail; |
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/* Skip EOF-chars.. */ |
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while (MASK(head) != MASK(tail)) { |
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if (test_bit(tail & (N_TTY_BUF_SIZE - 1), ldata->read_flags) && |
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read_buf(ldata, tail) == __DISABLED_CHAR) |
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nr--; |
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tail++; |
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} |
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return nr; |
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} |
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static int n_tty_ioctl(struct tty_struct *tty, struct file *file, |
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unsigned int cmd, unsigned long arg) |
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{ |
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struct n_tty_data *ldata = tty->disc_data; |
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int retval; |
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switch (cmd) { |
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case TIOCOUTQ: |
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return put_user(tty_chars_in_buffer(tty), (int __user *) arg); |
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case TIOCINQ: |
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down_write(&tty->termios_rwsem); |
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if (L_ICANON(tty) && !L_EXTPROC(tty)) |
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retval = inq_canon(ldata); |
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else |
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retval = read_cnt(ldata); |
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up_write(&tty->termios_rwsem); |
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return put_user(retval, (unsigned int __user *) arg); |
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default: |
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return n_tty_ioctl_helper(tty, file, cmd, arg); |
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} |
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} |
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static struct tty_ldisc_ops n_tty_ops = { |
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.owner = THIS_MODULE, |
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.num = N_TTY, |
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.name = "n_tty", |
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.open = n_tty_open, |
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.close = n_tty_close, |
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.flush_buffer = n_tty_flush_buffer, |
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.read = n_tty_read, |
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.write = n_tty_write, |
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.ioctl = n_tty_ioctl, |
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.set_termios = n_tty_set_termios, |
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.poll = n_tty_poll, |
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.receive_buf = n_tty_receive_buf, |
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.write_wakeup = n_tty_write_wakeup, |
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.receive_buf2 = n_tty_receive_buf2, |
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}; |
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/** |
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* n_tty_inherit_ops - inherit N_TTY methods |
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* @ops: struct tty_ldisc_ops where to save N_TTY methods |
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* |
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* Enables a 'subclass' line discipline to 'inherit' N_TTY methods. |
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*/ |
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void n_tty_inherit_ops(struct tty_ldisc_ops *ops) |
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{ |
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*ops = n_tty_ops; |
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ops->owner = NULL; |
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ops->flags = 0; |
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} |
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EXPORT_SYMBOL_GPL(n_tty_inherit_ops); |
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void __init n_tty_init(void) |
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{ |
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tty_register_ldisc(&n_tty_ops); |
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}
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