1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_TTY_H
3#define _LINUX_TTY_H
4
5#include <linux/fs.h>
6#include <linux/major.h>
7#include <linux/termios.h>
8#include <linux/workqueue.h>
9#include <linux/tty_driver.h>
10#include <linux/tty_ldisc.h>
11#include <linux/tty_port.h>
12#include <linux/mutex.h>
13#include <linux/tty_flags.h>
14#include <uapi/linux/tty.h>
15#include <linux/rwsem.h>
16#include <linux/llist.h>
17
18
19/*
20 * (Note: the *_driver.minor_start values 1, 64, 128, 192 are
21 * hardcoded at present.)
22 */
23#define NR_UNIX98_PTY_DEFAULT 4096 /* Default maximum for Unix98 ptys */
24#define NR_UNIX98_PTY_RESERVE 1024 /* Default reserve for main devpts */
25#define NR_UNIX98_PTY_MAX (1 << MINORBITS) /* Absolute limit */
26
27/*
28 * This character is the same as _POSIX_VDISABLE: it cannot be used as
29 * a c_cc[] character, but indicates that a particular special character
30 * isn't in use (eg VINTR has no character etc)
31 */
32#define __DISABLED_CHAR '\0'
33
34#define INTR_CHAR(tty) ((tty)->termios.c_cc[VINTR])
35#define QUIT_CHAR(tty) ((tty)->termios.c_cc[VQUIT])
36#define ERASE_CHAR(tty) ((tty)->termios.c_cc[VERASE])
37#define KILL_CHAR(tty) ((tty)->termios.c_cc[VKILL])
38#define EOF_CHAR(tty) ((tty)->termios.c_cc[VEOF])
39#define TIME_CHAR(tty) ((tty)->termios.c_cc[VTIME])
40#define MIN_CHAR(tty) ((tty)->termios.c_cc[VMIN])
41#define SWTC_CHAR(tty) ((tty)->termios.c_cc[VSWTC])
42#define START_CHAR(tty) ((tty)->termios.c_cc[VSTART])
43#define STOP_CHAR(tty) ((tty)->termios.c_cc[VSTOP])
44#define SUSP_CHAR(tty) ((tty)->termios.c_cc[VSUSP])
45#define EOL_CHAR(tty) ((tty)->termios.c_cc[VEOL])
46#define REPRINT_CHAR(tty) ((tty)->termios.c_cc[VREPRINT])
47#define DISCARD_CHAR(tty) ((tty)->termios.c_cc[VDISCARD])
48#define WERASE_CHAR(tty) ((tty)->termios.c_cc[VWERASE])
49#define LNEXT_CHAR(tty) ((tty)->termios.c_cc[VLNEXT])
50#define EOL2_CHAR(tty) ((tty)->termios.c_cc[VEOL2])
51
52#define _I_FLAG(tty, f) ((tty)->termios.c_iflag & (f))
53#define _O_FLAG(tty, f) ((tty)->termios.c_oflag & (f))
54#define _C_FLAG(tty, f) ((tty)->termios.c_cflag & (f))
55#define _L_FLAG(tty, f) ((tty)->termios.c_lflag & (f))
56
57#define I_IGNBRK(tty) _I_FLAG((tty), IGNBRK)
58#define I_BRKINT(tty) _I_FLAG((tty), BRKINT)
59#define I_IGNPAR(tty) _I_FLAG((tty), IGNPAR)
60#define I_PARMRK(tty) _I_FLAG((tty), PARMRK)
61#define I_INPCK(tty) _I_FLAG((tty), INPCK)
62#define I_ISTRIP(tty) _I_FLAG((tty), ISTRIP)
63#define I_INLCR(tty) _I_FLAG((tty), INLCR)
64#define I_IGNCR(tty) _I_FLAG((tty), IGNCR)
65#define I_ICRNL(tty) _I_FLAG((tty), ICRNL)
66#define I_IUCLC(tty) _I_FLAG((tty), IUCLC)
67#define I_IXON(tty) _I_FLAG((tty), IXON)
68#define I_IXANY(tty) _I_FLAG((tty), IXANY)
69#define I_IXOFF(tty) _I_FLAG((tty), IXOFF)
70#define I_IMAXBEL(tty) _I_FLAG((tty), IMAXBEL)
71#define I_IUTF8(tty) _I_FLAG((tty), IUTF8)
72
73#define O_OPOST(tty) _O_FLAG((tty), OPOST)
74#define O_OLCUC(tty) _O_FLAG((tty), OLCUC)
75#define O_ONLCR(tty) _O_FLAG((tty), ONLCR)
76#define O_OCRNL(tty) _O_FLAG((tty), OCRNL)
77#define O_ONOCR(tty) _O_FLAG((tty), ONOCR)
78#define O_ONLRET(tty) _O_FLAG((tty), ONLRET)
79#define O_OFILL(tty) _O_FLAG((tty), OFILL)
80#define O_OFDEL(tty) _O_FLAG((tty), OFDEL)
81#define O_NLDLY(tty) _O_FLAG((tty), NLDLY)
82#define O_CRDLY(tty) _O_FLAG((tty), CRDLY)
83#define O_TABDLY(tty) _O_FLAG((tty), TABDLY)
84#define O_BSDLY(tty) _O_FLAG((tty), BSDLY)
85#define O_VTDLY(tty) _O_FLAG((tty), VTDLY)
86#define O_FFDLY(tty) _O_FLAG((tty), FFDLY)
87
88#define C_BAUD(tty) _C_FLAG((tty), CBAUD)
89#define C_CSIZE(tty) _C_FLAG((tty), CSIZE)
90#define C_CSTOPB(tty) _C_FLAG((tty), CSTOPB)
91#define C_CREAD(tty) _C_FLAG((tty), CREAD)
92#define C_PARENB(tty) _C_FLAG((tty), PARENB)
93#define C_PARODD(tty) _C_FLAG((tty), PARODD)
94#define C_HUPCL(tty) _C_FLAG((tty), HUPCL)
95#define C_CLOCAL(tty) _C_FLAG((tty), CLOCAL)
96#define C_CIBAUD(tty) _C_FLAG((tty), CIBAUD)
97#define C_CRTSCTS(tty) _C_FLAG((tty), CRTSCTS)
98#define C_CMSPAR(tty) _C_FLAG((tty), CMSPAR)
99
100#define L_ISIG(tty) _L_FLAG((tty), ISIG)
101#define L_ICANON(tty) _L_FLAG((tty), ICANON)
102#define L_XCASE(tty) _L_FLAG((tty), XCASE)
103#define L_ECHO(tty) _L_FLAG((tty), ECHO)
104#define L_ECHOE(tty) _L_FLAG((tty), ECHOE)
105#define L_ECHOK(tty) _L_FLAG((tty), ECHOK)
106#define L_ECHONL(tty) _L_FLAG((tty), ECHONL)
107#define L_NOFLSH(tty) _L_FLAG((tty), NOFLSH)
108#define L_TOSTOP(tty) _L_FLAG((tty), TOSTOP)
109#define L_ECHOCTL(tty) _L_FLAG((tty), ECHOCTL)
110#define L_ECHOPRT(tty) _L_FLAG((tty), ECHOPRT)
111#define L_ECHOKE(tty) _L_FLAG((tty), ECHOKE)
112#define L_FLUSHO(tty) _L_FLAG((tty), FLUSHO)
113#define L_PENDIN(tty) _L_FLAG((tty), PENDIN)
114#define L_IEXTEN(tty) _L_FLAG((tty), IEXTEN)
115#define L_EXTPROC(tty) _L_FLAG((tty), EXTPROC)
116
117struct device;
118struct signal_struct;
119struct tty_operations;
120
121/**
122 * struct tty_struct - state associated with a tty while open
123 *
124 * @kref: reference counting by tty_kref_get() and tty_kref_put(), reaching zero
125 * frees the structure
126 * @dev: class device or %NULL (e.g. ptys, serdev)
127 * @driver: &struct tty_driver operating this tty
128 * @ops: &struct tty_operations of @driver for this tty (open, close, etc.)
129 * @index: index of this tty (e.g. to construct @name like tty12)
130 * @ldisc_sem: protects line discipline changes (@ldisc) -- lock tty not pty
131 * @ldisc: the current line discipline for this tty (n_tty by default)
132 * @atomic_write_lock: protects against concurrent writers, i.e. locks
133 * @write_cnt, @write_buf and similar
134 * @legacy_mutex: leftover from history (BKL -> BTM -> @legacy_mutex),
135 * protecting several operations on this tty
136 * @throttle_mutex: protects against concurrent tty_throttle_safe() and
137 * tty_unthrottle_safe() (but not tty_unthrottle())
138 * @termios_rwsem: protects @termios and @termios_locked
139 * @winsize_mutex: protects @winsize
140 * @termios: termios for the current tty, copied from/to @driver.termios
141 * @termios_locked: locked termios (by %TIOCGLCKTRMIOS and %TIOCSLCKTRMIOS
142 * ioctls)
143 * @name: name of the tty constructed by tty_line_name() (e.g. ttyS3)
144 * @flags: bitwise OR of %TTY_THROTTLED, %TTY_IO_ERROR, ...
145 * @count: count of open processes, reaching zero cancels all the work for
146 * this tty and drops a @kref too (but does not free this tty)
147 * @winsize: size of the terminal "window" (cf. @winsize_mutex)
148 * @flow: flow settings grouped together, see also @flow.unused
149 * @flow.lock: lock for @flow members
150 * @flow.stopped: tty stopped/started by stop_tty()/start_tty()
151 * @flow.tco_stopped: tty stopped/started by %TCOOFF/%TCOON ioctls (it has
152 * precedence over @flow.stopped)
153 * @flow.unused: alignment for Alpha, so that no members other than @flow.* are
154 * modified by the same 64b word store. The @flow's __aligned is
155 * there for the very same reason.
156 * @ctrl: control settings grouped together, see also @ctrl.unused
157 * @ctrl.lock: lock for @ctrl members
158 * @ctrl.pgrp: process group of this tty (setpgrp(2))
159 * @ctrl.session: session of this tty (setsid(2)). Writes are protected by both
160 * @ctrl.lock and @legacy_mutex, readers must use at least one of
161 * them.
162 * @ctrl.pktstatus: packet mode status (bitwise OR of %TIOCPKT_ constants)
163 * @ctrl.packet: packet mode enabled
164 * @ctrl.unused: alignment for Alpha, see @flow.unused for explanation
165 * @hw_stopped: not controlled by the tty layer, under @driver's control for CTS
166 * handling
167 * @receive_room: bytes permitted to feed to @ldisc without any being lost
168 * @flow_change: controls behavior of throttling, see tty_throttle_safe() and
169 * tty_unthrottle_safe()
170 * @link: link to another pty (master -> slave and vice versa)
171 * @fasync: state for %O_ASYNC (for %SIGIO); managed by fasync_helper()
172 * @write_wait: concurrent writers are waiting in this queue until they are
173 * allowed to write
174 * @read_wait: readers wait for data in this queue
175 * @hangup_work: normally a work to perform a hangup (do_tty_hangup()); while
176 * freeing the tty, (re)used to release_one_tty()
177 * @disc_data: pointer to @ldisc's private data (e.g. to &struct n_tty_data)
178 * @driver_data: pointer to @driver's private data (e.g. &struct uart_state)
179 * @files_lock: protects @tty_files list
180 * @tty_files: list of (re)openers of this tty (i.e. linked &struct
181 * tty_file_private)
182 * @closing: when set during close, n_tty processes only START & STOP chars
183 * @write_buf: temporary buffer used during tty_write() to copy user data to
184 * @write_cnt: count of bytes written in tty_write() to @write_buf
185 * @SAK_work: if the tty has a pending do_SAK, it is queued here
186 * @port: persistent storage for this device (i.e. &struct tty_port)
187 *
188 * All of the state associated with a tty while the tty is open. Persistent
189 * storage for tty devices is referenced here as @port and is documented in
190 * &struct tty_port.
191 */
192struct tty_struct {
193 struct kref kref;
194 int index;
195 struct device *dev;
196 struct tty_driver *driver;
197 struct tty_port *port;
198 const struct tty_operations *ops;
199
200 struct tty_ldisc *ldisc;
201 struct ld_semaphore ldisc_sem;
202
203 struct mutex atomic_write_lock;
204 struct mutex legacy_mutex;
205 struct mutex throttle_mutex;
206 struct rw_semaphore termios_rwsem;
207 struct mutex winsize_mutex;
208 struct ktermios termios, termios_locked;
209 char name[64];
210 unsigned long flags;
211 int count;
212 unsigned int receive_room;
213 struct winsize winsize;
214
215 struct {
216 spinlock_t lock;
217 bool stopped;
218 bool tco_stopped;
219 unsigned long unused[0];
220 } __aligned(sizeof(unsigned long)) flow;
221
222 struct {
223 struct pid *pgrp;
224 struct pid *session;
225 spinlock_t lock;
226 unsigned char pktstatus;
227 bool packet;
228 unsigned long unused[0];
229 } __aligned(sizeof(unsigned long)) ctrl;
230
231 bool hw_stopped;
232 bool closing;
233 int flow_change;
234
235 struct tty_struct *link;
236 struct fasync_struct *fasync;
237 wait_queue_head_t write_wait;
238 wait_queue_head_t read_wait;
239 struct work_struct hangup_work;
240 void *disc_data;
241 void *driver_data;
242 spinlock_t files_lock;
243 int write_cnt;
244 u8 *write_buf;
245
246 struct list_head tty_files;
247
248#define N_TTY_BUF_SIZE 4096
249 struct work_struct SAK_work;
250} __randomize_layout;
251
252/* Each of a tty's open files has private_data pointing to tty_file_private */
253struct tty_file_private {
254 struct tty_struct *tty;
255 struct file *file;
256 struct list_head list;
257};
258
259/**
260 * DOC: TTY Struct Flags
261 *
262 * These bits are used in the :c:member:`tty_struct.flags` field.
263 *
264 * So that interrupts won't be able to mess up the queues,
265 * copy_to_cooked must be atomic with respect to itself, as must
266 * tty->write. Thus, you must use the inline functions set_bit() and
267 * clear_bit() to make things atomic.
268 *
269 * TTY_THROTTLED
270 * Driver input is throttled. The ldisc should call
271 * :c:member:`tty_driver.unthrottle()` in order to resume reception when
272 * it is ready to process more data (at threshold min).
273 *
274 * TTY_IO_ERROR
275 * If set, causes all subsequent userspace read/write calls on the tty to
276 * fail, returning -%EIO. (May be no ldisc too.)
277 *
278 * TTY_OTHER_CLOSED
279 * Device is a pty and the other side has closed.
280 *
281 * TTY_EXCLUSIVE
282 * Exclusive open mode (a single opener).
283 *
284 * TTY_DO_WRITE_WAKEUP
285 * If set, causes the driver to call the
286 * :c:member:`tty_ldisc_ops.write_wakeup()` method in order to resume
287 * transmission when it can accept more data to transmit.
288 *
289 * TTY_LDISC_OPEN
290 * Indicates that a line discipline is open. For debugging purposes only.
291 *
292 * TTY_PTY_LOCK
293 * A flag private to pty code to implement %TIOCSPTLCK/%TIOCGPTLCK logic.
294 *
295 * TTY_NO_WRITE_SPLIT
296 * Prevent driver from splitting up writes into smaller chunks (preserve
297 * write boundaries to driver).
298 *
299 * TTY_HUPPED
300 * The TTY was hung up. This is set post :c:member:`tty_driver.hangup()`.
301 *
302 * TTY_HUPPING
303 * The TTY is in the process of hanging up to abort potential readers.
304 *
305 * TTY_LDISC_CHANGING
306 * Line discipline for this TTY is being changed. I/O should not block
307 * when this is set. Use tty_io_nonblock() to check.
308 *
309 * TTY_LDISC_HALTED
310 * Line discipline for this TTY was stopped. No work should be queued to
311 * this ldisc.
312 */
313#define TTY_THROTTLED 0
314#define TTY_IO_ERROR 1
315#define TTY_OTHER_CLOSED 2
316#define TTY_EXCLUSIVE 3
317#define TTY_DO_WRITE_WAKEUP 5
318#define TTY_LDISC_OPEN 11
319#define TTY_PTY_LOCK 16
320#define TTY_NO_WRITE_SPLIT 17
321#define TTY_HUPPED 18
322#define TTY_HUPPING 19
323#define TTY_LDISC_CHANGING 20
324#define TTY_LDISC_HALTED 22
325
326static inline bool tty_io_nonblock(struct tty_struct *tty, struct file *file)
327{
328 return file->f_flags & O_NONBLOCK ||
329 test_bit(TTY_LDISC_CHANGING, &tty->flags);
330}
331
332static inline bool tty_io_error(struct tty_struct *tty)
333{
334 return test_bit(TTY_IO_ERROR, &tty->flags);
335}
336
337static inline bool tty_throttled(struct tty_struct *tty)
338{
339 return test_bit(TTY_THROTTLED, &tty->flags);
340}
341
342#ifdef CONFIG_TTY
343void tty_kref_put(struct tty_struct *tty);
344struct pid *tty_get_pgrp(struct tty_struct *tty);
345void tty_vhangup_self(void);
346void disassociate_ctty(int priv);
347dev_t tty_devnum(struct tty_struct *tty);
348void proc_clear_tty(struct task_struct *p);
349struct tty_struct *get_current_tty(void);
350/* tty_io.c */
351int __init tty_init(void);
352const char *tty_name(const struct tty_struct *tty);
353struct tty_struct *tty_kopen_exclusive(dev_t device);
354struct tty_struct *tty_kopen_shared(dev_t device);
355void tty_kclose(struct tty_struct *tty);
356int tty_dev_name_to_number(const char *name, dev_t *number);
357#else
358static inline void tty_kref_put(struct tty_struct *tty)
359{ }
360static inline struct pid *tty_get_pgrp(struct tty_struct *tty)
361{ return NULL; }
362static inline void tty_vhangup_self(void)
363{ }
364static inline void disassociate_ctty(int priv)
365{ }
366static inline dev_t tty_devnum(struct tty_struct *tty)
367{ return 0; }
368static inline void proc_clear_tty(struct task_struct *p)
369{ }
370static inline struct tty_struct *get_current_tty(void)
371{ return NULL; }
372/* tty_io.c */
373static inline int __init tty_init(void)
374{ return 0; }
375static inline const char *tty_name(const struct tty_struct *tty)
376{ return "(none)"; }
377static inline struct tty_struct *tty_kopen_exclusive(dev_t device)
378{ return ERR_PTR(-ENODEV); }
379static inline void tty_kclose(struct tty_struct *tty)
380{ }
381static inline int tty_dev_name_to_number(const char *name, dev_t *number)
382{ return -ENOTSUPP; }
383#endif
384
385extern struct ktermios tty_std_termios;
386
387int vcs_init(void);
388
389extern const struct class tty_class;
390
391/**
392 * tty_kref_get - get a tty reference
393 * @tty: tty device
394 *
395 * Returns: a new reference to a tty object
396 *
397 * Locking: The caller must hold sufficient locks/counts to ensure that their
398 * existing reference cannot go away.
399 */
400static inline struct tty_struct *tty_kref_get(struct tty_struct *tty)
401{
402 if (tty)
403 kref_get(kref: &tty->kref);
404 return tty;
405}
406
407const char *tty_driver_name(const struct tty_struct *tty);
408void tty_wait_until_sent(struct tty_struct *tty, long timeout);
409void stop_tty(struct tty_struct *tty);
410void start_tty(struct tty_struct *tty);
411void tty_write_message(struct tty_struct *tty, char *msg);
412int tty_send_xchar(struct tty_struct *tty, u8 ch);
413int tty_put_char(struct tty_struct *tty, u8 c);
414unsigned int tty_chars_in_buffer(struct tty_struct *tty);
415unsigned int tty_write_room(struct tty_struct *tty);
416void tty_driver_flush_buffer(struct tty_struct *tty);
417void tty_unthrottle(struct tty_struct *tty);
418bool tty_throttle_safe(struct tty_struct *tty);
419bool tty_unthrottle_safe(struct tty_struct *tty);
420int tty_do_resize(struct tty_struct *tty, struct winsize *ws);
421int tty_get_icount(struct tty_struct *tty,
422 struct serial_icounter_struct *icount);
423int tty_get_tiocm(struct tty_struct *tty);
424int is_current_pgrp_orphaned(void);
425void tty_hangup(struct tty_struct *tty);
426void tty_vhangup(struct tty_struct *tty);
427int tty_hung_up_p(struct file *filp);
428void do_SAK(struct tty_struct *tty);
429void __do_SAK(struct tty_struct *tty);
430void no_tty(void);
431speed_t tty_termios_baud_rate(const struct ktermios *termios);
432void tty_termios_encode_baud_rate(struct ktermios *termios, speed_t ibaud,
433 speed_t obaud);
434void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud,
435 speed_t obaud);
436
437/**
438 * tty_get_baud_rate - get tty bit rates
439 * @tty: tty to query
440 *
441 * Returns: the baud rate as an integer for this terminal
442 *
443 * Locking: The termios lock must be held by the caller.
444 */
445static inline speed_t tty_get_baud_rate(const struct tty_struct *tty)
446{
447 return tty_termios_baud_rate(termios: &tty->termios);
448}
449
450unsigned char tty_get_char_size(unsigned int cflag);
451unsigned char tty_get_frame_size(unsigned int cflag);
452
453void tty_termios_copy_hw(struct ktermios *new, const struct ktermios *old);
454bool tty_termios_hw_change(const struct ktermios *a, const struct ktermios *b);
455int tty_set_termios(struct tty_struct *tty, struct ktermios *kt);
456
457void tty_wakeup(struct tty_struct *tty);
458
459int tty_mode_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg);
460int tty_perform_flush(struct tty_struct *tty, unsigned long arg);
461struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx);
462void tty_release_struct(struct tty_struct *tty, int idx);
463void tty_init_termios(struct tty_struct *tty);
464void tty_save_termios(struct tty_struct *tty);
465int tty_standard_install(struct tty_driver *driver,
466 struct tty_struct *tty);
467
468extern struct mutex tty_mutex;
469
470/* n_tty.c */
471void n_tty_inherit_ops(struct tty_ldisc_ops *ops);
472#ifdef CONFIG_TTY
473void __init n_tty_init(void);
474#else
475static inline void n_tty_init(void) { }
476#endif
477
478/* tty_audit.c */
479#ifdef CONFIG_AUDIT
480void tty_audit_exit(void);
481void tty_audit_fork(struct signal_struct *sig);
482int tty_audit_push(void);
483#else
484static inline void tty_audit_exit(void)
485{
486}
487static inline void tty_audit_fork(struct signal_struct *sig)
488{
489}
490static inline int tty_audit_push(void)
491{
492 return 0;
493}
494#endif
495
496/* tty_ioctl.c */
497int n_tty_ioctl_helper(struct tty_struct *tty, unsigned int cmd,
498 unsigned long arg);
499
500/* vt.c */
501
502int vt_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg);
503
504long vt_compat_ioctl(struct tty_struct *tty, unsigned int cmd,
505 unsigned long arg);
506
507/* tty_mutex.c */
508/* functions for preparation of BKL removal */
509void tty_lock(struct tty_struct *tty);
510int tty_lock_interruptible(struct tty_struct *tty);
511void tty_unlock(struct tty_struct *tty);
512void tty_lock_slave(struct tty_struct *tty);
513void tty_unlock_slave(struct tty_struct *tty);
514void tty_set_lock_subclass(struct tty_struct *tty);
515
516#endif
517

source code of linux/include/linux/tty.h