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
117 struct device;
118 struct signal_struct;
119 struct 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
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 * @ctrl: control settings grouped together
154 * @ctrl.lock: lock for @ctrl members
155 * @ctrl.pgrp: process group of this tty (setpgrp(2))
156 * @ctrl.session: session of this tty (setsid(2)). Writes are protected by both
157 * @ctrl.lock and @legacy_mutex, readers must use at least one of
158 * them.
159 * @ctrl.pktstatus: packet mode status (bitwise OR of %TIOCPKT_ constants)
160 * @ctrl.packet: packet mode enabled
161 * @hw_stopped: not controlled by the tty layer, under @driver's control for CTS
162 * handling
163 * @receive_room: bytes permitted to feed to @ldisc without any being lost
164 * @flow_change: controls behavior of throttling, see tty_throttle_safe() and
165 * tty_unthrottle_safe()
166 * @link: link to another pty (master -> slave and vice versa)
167 * @fasync: state for %O_ASYNC (for %SIGIO); managed by fasync_helper()
168 * @write_wait: concurrent writers are waiting in this queue until they are
169 * allowed to write
170 * @read_wait: readers wait for data in this queue
171 * @hangup_work: normally a work to perform a hangup (do_tty_hangup()); while
172 * freeing the tty, (re)used to release_one_tty()
173 * @disc_data: pointer to @ldisc's private data (e.g. to &struct n_tty_data)
174 * @driver_data: pointer to @driver's private data (e.g. &struct uart_state)
175 * @files_lock: protects @tty_files list
176 * @tty_files: list of (re)openers of this tty (i.e. linked &struct
177 * tty_file_private)
178 * @closing: when set during close, n_tty processes only START & STOP chars
179 * @write_buf: temporary buffer used during tty_write() to copy user data to
180 * @write_cnt: count of bytes written in tty_write() to @write_buf
181 * @SAK_work: if the tty has a pending do_SAK, it is queued here
182 * @port: persistent storage for this device (i.e. &struct tty_port)
183 *
184 * All of the state associated with a tty while the tty is open. Persistent
185 * storage for tty devices is referenced here as @port and is documented in
186 * &struct tty_port.
187 */
188 struct tty_struct {
189 struct kref kref;
190 int index;
191 struct device *dev;
192 struct tty_driver *driver;
193 struct tty_port *port;
194 const struct tty_operations *ops;
195
196 struct tty_ldisc *ldisc;
197 struct ld_semaphore ldisc_sem;
198
199 struct mutex atomic_write_lock;
200 struct mutex legacy_mutex;
201 struct mutex throttle_mutex;
202 struct rw_semaphore termios_rwsem;
203 struct mutex winsize_mutex;
204 struct ktermios termios, termios_locked;
205 char name[64];
206 unsigned long flags;
207 int count;
208 unsigned int receive_room;
209 struct winsize winsize;
210
211 struct {
212 spinlock_t lock;
213 bool stopped;
214 bool tco_stopped;
215 } flow;
216
217 struct {
218 struct pid *pgrp;
219 struct pid *session;
220 spinlock_t lock;
221 unsigned char pktstatus;
222 bool packet;
223 } ctrl;
224
225 bool hw_stopped;
226 bool closing;
227 int flow_change;
228
229 struct tty_struct *link;
230 struct fasync_struct *fasync;
231 wait_queue_head_t write_wait;
232 wait_queue_head_t read_wait;
233 struct work_struct hangup_work;
234 void *disc_data;
235 void *driver_data;
236 spinlock_t files_lock;
237 int write_cnt;
238 u8 *write_buf;
239
240 struct list_head tty_files;
241
242 struct work_struct SAK_work;
243 } __randomize_layout;
244
245 /* Each of a tty's open files has private_data pointing to tty_file_private */
246 struct tty_file_private {
247 struct tty_struct *tty;
248 struct file *file;
249 struct list_head list;
250 };
251
252 /**
253 * enum tty_struct_flags - TTY Struct Flags
254 *
255 * These bits are used in the :c:member:`tty_struct.flags` field.
256 *
257 * So that interrupts won't be able to mess up the queues,
258 * copy_to_cooked must be atomic with respect to itself, as must
259 * tty->write. Thus, you must use the inline functions set_bit() and
260 * clear_bit() to make things atomic.
261 *
262 * @TTY_THROTTLED:
263 * Driver input is throttled. The ldisc should call
264 * :c:member:`tty_driver.unthrottle()` in order to resume reception when
265 * it is ready to process more data (at threshold min).
266 *
267 * @TTY_IO_ERROR:
268 * If set, causes all subsequent userspace read/write calls on the tty to
269 * fail, returning -%EIO. (May be no ldisc too.)
270 *
271 * @TTY_OTHER_CLOSED:
272 * Device is a pty and the other side has closed.
273 *
274 * @TTY_EXCLUSIVE:
275 * Exclusive open mode (a single opener).
276 *
277 * @TTY_DO_WRITE_WAKEUP:
278 * If set, causes the driver to call the
279 * :c:member:`tty_ldisc_ops.write_wakeup()` method in order to resume
280 * transmission when it can accept more data to transmit.
281 *
282 * @TTY_LDISC_OPEN:
283 * Indicates that a line discipline is open. For debugging purposes only.
284 *
285 * @TTY_PTY_LOCK:
286 * A flag private to pty code to implement %TIOCSPTLCK/%TIOCGPTLCK logic.
287 *
288 * @TTY_NO_WRITE_SPLIT:
289 * Prevent driver from splitting up writes into smaller chunks (preserve
290 * write boundaries to driver).
291 *
292 * @TTY_HUPPED:
293 * The TTY was hung up. This is set post :c:member:`tty_driver.hangup()`.
294 *
295 * @TTY_HUPPING:
296 * The TTY is in the process of hanging up to abort potential readers.
297 *
298 * @TTY_LDISC_CHANGING:
299 * Line discipline for this TTY is being changed. I/O should not block
300 * when this is set. Use tty_io_nonblock() to check.
301 *
302 * @TTY_LDISC_HALTED:
303 * Line discipline for this TTY was stopped. No work should be queued to
304 * this ldisc.
305 */
306 enum tty_struct_flags {
307 TTY_THROTTLED,
308 TTY_IO_ERROR,
309 TTY_OTHER_CLOSED,
310 TTY_EXCLUSIVE,
311 TTY_DO_WRITE_WAKEUP,
312 TTY_LDISC_OPEN,
313 TTY_PTY_LOCK,
314 TTY_NO_WRITE_SPLIT,
315 TTY_HUPPED,
316 TTY_HUPPING,
317 TTY_LDISC_CHANGING,
318 TTY_LDISC_HALTED,
319 };
320
tty_io_nonblock(struct tty_struct * tty,struct file * file)321 static inline bool tty_io_nonblock(struct tty_struct *tty, struct file *file)
322 {
323 return file->f_flags & O_NONBLOCK ||
324 test_bit(TTY_LDISC_CHANGING, &tty->flags);
325 }
326
tty_io_error(struct tty_struct * tty)327 static inline bool tty_io_error(struct tty_struct *tty)
328 {
329 return test_bit(TTY_IO_ERROR, &tty->flags);
330 }
331
tty_throttled(struct tty_struct * tty)332 static inline bool tty_throttled(struct tty_struct *tty)
333 {
334 return test_bit(TTY_THROTTLED, &tty->flags);
335 }
336
337 #ifdef CONFIG_TTY
338 void tty_kref_put(struct tty_struct *tty);
339 struct pid *tty_get_pgrp(struct tty_struct *tty);
340 void tty_vhangup_self(void);
341 void disassociate_ctty(int priv);
342 dev_t tty_devnum(struct tty_struct *tty);
343 void proc_clear_tty(struct task_struct *p);
344 struct tty_struct *get_current_tty(void);
345 /* tty_io.c */
346 int __init tty_init(void);
347 const char *tty_name(const struct tty_struct *tty);
348 struct tty_struct *tty_kopen_exclusive(dev_t device);
349 struct tty_struct *tty_kopen_shared(dev_t device);
350 void tty_kclose(struct tty_struct *tty);
351 int tty_dev_name_to_number(const char *name, dev_t *number);
352 #else
tty_kref_put(struct tty_struct * tty)353 static inline void tty_kref_put(struct tty_struct *tty)
354 { }
tty_get_pgrp(struct tty_struct * tty)355 static inline struct pid *tty_get_pgrp(struct tty_struct *tty)
356 { return NULL; }
tty_vhangup_self(void)357 static inline void tty_vhangup_self(void)
358 { }
disassociate_ctty(int priv)359 static inline void disassociate_ctty(int priv)
360 { }
tty_devnum(struct tty_struct * tty)361 static inline dev_t tty_devnum(struct tty_struct *tty)
362 { return 0; }
proc_clear_tty(struct task_struct * p)363 static inline void proc_clear_tty(struct task_struct *p)
364 { }
get_current_tty(void)365 static inline struct tty_struct *get_current_tty(void)
366 { return NULL; }
367 /* tty_io.c */
tty_init(void)368 static inline int __init tty_init(void)
369 { return 0; }
tty_name(const struct tty_struct * tty)370 static inline const char *tty_name(const struct tty_struct *tty)
371 { return "(none)"; }
tty_kopen_exclusive(dev_t device)372 static inline struct tty_struct *tty_kopen_exclusive(dev_t device)
373 { return ERR_PTR(-ENODEV); }
tty_kclose(struct tty_struct * tty)374 static inline void tty_kclose(struct tty_struct *tty)
375 { }
tty_dev_name_to_number(const char * name,dev_t * number)376 static inline int tty_dev_name_to_number(const char *name, dev_t *number)
377 { return -ENOTSUPP; }
378 #endif
379
380 extern struct ktermios tty_std_termios;
381
382 int vcs_init(void);
383
384 extern const struct class tty_class;
385
386 /**
387 * tty_kref_get - get a tty reference
388 * @tty: tty device
389 *
390 * Returns: a new reference to a tty object
391 *
392 * Locking: The caller must hold sufficient locks/counts to ensure that their
393 * existing reference cannot go away.
394 */
tty_kref_get(struct tty_struct * tty)395 static inline struct tty_struct *tty_kref_get(struct tty_struct *tty)
396 {
397 if (tty)
398 kref_get(&tty->kref);
399 return tty;
400 }
401
402 const char *tty_driver_name(const struct tty_struct *tty);
403 void tty_wait_until_sent(struct tty_struct *tty, long timeout);
404 void stop_tty(struct tty_struct *tty);
405 void start_tty(struct tty_struct *tty);
406 void tty_write_message(struct tty_struct *tty, char *msg);
407 int tty_send_xchar(struct tty_struct *tty, u8 ch);
408 int tty_put_char(struct tty_struct *tty, u8 c);
409 unsigned int tty_chars_in_buffer(struct tty_struct *tty);
410 unsigned int tty_write_room(struct tty_struct *tty);
411 void tty_driver_flush_buffer(struct tty_struct *tty);
412 void tty_unthrottle(struct tty_struct *tty);
413 bool tty_throttle_safe(struct tty_struct *tty);
414 bool tty_unthrottle_safe(struct tty_struct *tty);
415 int tty_do_resize(struct tty_struct *tty, struct winsize *ws);
416 int tty_get_icount(struct tty_struct *tty,
417 struct serial_icounter_struct *icount);
418 int tty_get_tiocm(struct tty_struct *tty);
419 int is_current_pgrp_orphaned(void);
420 void tty_hangup(struct tty_struct *tty);
421 void tty_vhangup(struct tty_struct *tty);
422 int tty_hung_up_p(struct file *filp);
423 void do_SAK(struct tty_struct *tty);
424 void __do_SAK(struct tty_struct *tty);
425 void no_tty(void);
426 speed_t tty_termios_baud_rate(const struct ktermios *termios);
427 void tty_termios_encode_baud_rate(struct ktermios *termios, speed_t ibaud,
428 speed_t obaud);
429 void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud,
430 speed_t obaud);
431
432 /**
433 * tty_get_baud_rate - get tty bit rates
434 * @tty: tty to query
435 *
436 * Returns: the baud rate as an integer for this terminal
437 *
438 * Locking: The termios lock must be held by the caller.
439 */
tty_get_baud_rate(const struct tty_struct * tty)440 static inline speed_t tty_get_baud_rate(const struct tty_struct *tty)
441 {
442 return tty_termios_baud_rate(&tty->termios);
443 }
444
445 unsigned char tty_get_char_size(unsigned int cflag);
446 unsigned char tty_get_frame_size(unsigned int cflag);
447
448 void tty_termios_copy_hw(struct ktermios *new, const struct ktermios *old);
449 bool tty_termios_hw_change(const struct ktermios *a, const struct ktermios *b);
450 int tty_set_termios(struct tty_struct *tty, struct ktermios *kt);
451
452 void tty_wakeup(struct tty_struct *tty);
453
454 int tty_mode_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg);
455 int tty_perform_flush(struct tty_struct *tty, unsigned long arg);
456 struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx);
457 void tty_release_struct(struct tty_struct *tty, int idx);
458 void tty_init_termios(struct tty_struct *tty);
459 void tty_save_termios(struct tty_struct *tty);
460 int tty_standard_install(struct tty_driver *driver,
461 struct tty_struct *tty);
462
463 extern struct mutex tty_mutex;
464
465 /* n_tty.c */
466 void n_tty_inherit_ops(struct tty_ldisc_ops *ops);
467 #ifdef CONFIG_TTY
468 void __init n_tty_init(void);
469 #else
n_tty_init(void)470 static inline void n_tty_init(void) { }
471 #endif
472
473 /* tty_audit.c */
474 #ifdef CONFIG_AUDIT
475 void tty_audit_exit(void);
476 void tty_audit_fork(struct signal_struct *sig);
477 int tty_audit_push(void);
478 #else
tty_audit_exit(void)479 static inline void tty_audit_exit(void)
480 {
481 }
tty_audit_fork(struct signal_struct * sig)482 static inline void tty_audit_fork(struct signal_struct *sig)
483 {
484 }
tty_audit_push(void)485 static inline int tty_audit_push(void)
486 {
487 return 0;
488 }
489 #endif
490
491 /* tty_ioctl.c */
492 int n_tty_ioctl_helper(struct tty_struct *tty, unsigned int cmd,
493 unsigned long arg);
494
495 /* vt.c */
496
497 int vt_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg);
498
499 long vt_compat_ioctl(struct tty_struct *tty, unsigned int cmd,
500 unsigned long arg);
501
502 /* tty_mutex.c */
503 /* functions for preparation of BKL removal */
504 void tty_lock(struct tty_struct *tty);
505 int tty_lock_interruptible(struct tty_struct *tty);
506 void tty_unlock(struct tty_struct *tty);
507 void tty_lock_slave(struct tty_struct *tty);
508 void tty_unlock_slave(struct tty_struct *tty);
509 void tty_set_lock_subclass(struct tty_struct *tty);
510
511 #endif
512