1/* 2 * linux/drivers/char/pty.c 3 * 4 * Copyright (C) 1991, 1992 Linus Torvalds 5 * 6 * Added support for a Unix98-style ptmx device. 7 * -- C. Scott Ananian <cananian@alumni.princeton.edu>, 14-Jan-1998 8 * Added TTY_DO_WRITE_WAKEUP to enable n_tty to send POLL_OUT to 9 * waiting writers -- Sapan Bhatia <sapan@corewars.org> 10 * 11 * 12 */ 13 14#include <linux/config.h> 15#include <linux/module.h> /* For EXPORT_SYMBOL */ 16 17#include <linux/errno.h> 18#include <linux/sched.h> 19#include <linux/interrupt.h> 20#include <linux/tty.h> 21#include <linux/tty_flip.h> 22#include <linux/fcntl.h> 23#include <linux/string.h> 24#include <linux/major.h> 25#include <linux/mm.h> 26#include <linux/init.h> 27#include <linux/devfs_fs_kernel.h> 28 29#include <asm/uaccess.h> 30#include <asm/system.h> 31#include <asm/bitops.h> 32 33#define BUILDING_PTY_C 1 34#include <linux/devpts_fs.h> 35 36struct pty_struct { 37 int magic; 38 wait_queue_head_t open_wait; 39}; 40 41#define PTY_MAGIC 0x5001 42 43static struct tty_driver pty_driver, pty_slave_driver; 44static int pty_refcount; 45 46/* Note: one set of tables for BSD and one for Unix98 */ 47static struct tty_struct *pty_table[NR_PTYS]; 48static struct termios *pty_termios[NR_PTYS]; 49static struct termios *pty_termios_locked[NR_PTYS]; 50static struct tty_struct *ttyp_table[NR_PTYS]; 51static struct termios *ttyp_termios[NR_PTYS]; 52static struct termios *ttyp_termios_locked[NR_PTYS]; 53static struct pty_struct pty_state[NR_PTYS]; 54 55#ifdef CONFIG_UNIX98_PTYS 56/* These are global because they are accessed in tty_io.c */ 57struct tty_driver ptm_driver[UNIX98_NR_MAJORS]; 58struct tty_driver pts_driver[UNIX98_NR_MAJORS]; 59 60static struct tty_struct *ptm_table[UNIX98_NR_MAJORS][NR_PTYS]; 61static struct termios *ptm_termios[UNIX98_NR_MAJORS][NR_PTYS]; 62static struct termios *ptm_termios_locked[UNIX98_NR_MAJORS][NR_PTYS]; 63static struct tty_struct *pts_table[UNIX98_NR_MAJORS][NR_PTYS]; 64static struct termios *pts_termios[UNIX98_NR_MAJORS][NR_PTYS]; 65static struct termios *pts_termios_locked[UNIX98_NR_MAJORS][NR_PTYS]; 66static struct pty_struct ptm_state[UNIX98_NR_MAJORS][NR_PTYS]; 67#endif 68 69#define MIN(a,b) ((a) < (b) ? (a) : (b)) 70 71static void pty_close(struct tty_struct * tty, struct file * filp) 72{ 73 if (!tty) 74 return; 75 if (tty->driver.subtype == PTY_TYPE_MASTER) { 76 if (tty->count > 1) 77 printk("master pty_close: count = %d!!\n", tty->count); 78 } else { 79 if (tty->count > 2) 80 return; 81 } 82 wake_up_interruptible(&tty->read_wait); 83 wake_up_interruptible(&tty->write_wait); 84 tty->packet = 0; 85 if (!tty->link) 86 return; 87 tty->link->packet = 0; 88 wake_up_interruptible(&tty->link->read_wait); 89 wake_up_interruptible(&tty->link->write_wait); 90 set_bit(TTY_OTHER_CLOSED, &tty->link->flags); 91 if (tty->driver.subtype == PTY_TYPE_MASTER) { 92 set_bit(TTY_OTHER_CLOSED, &tty->flags); 93#ifdef CONFIG_UNIX98_PTYS 94 { 95 unsigned int major = MAJOR(tty->device) - UNIX98_PTY_MASTER_MAJOR; 96 if ( major < UNIX98_NR_MAJORS ) { 97 devpts_pty_kill( MINOR(tty->device) 98 - tty->driver.minor_start + tty->driver.name_base ); 99 } 100 } 101#endif 102 tty_unregister_devfs (&tty->link->driver, MINOR (tty->device)); 103 tty_vhangup(tty->link); 104 } 105} 106 107/* 108 * The unthrottle routine is called by the line discipline to signal 109 * that it can receive more characters. For PTY's, the TTY_THROTTLED 110 * flag is always set, to force the line discipline to always call the 111 * unthrottle routine when there are fewer than TTY_THRESHOLD_UNTHROTTLE 112 * characters in the queue. This is necessary since each time this 113 * happens, we need to wake up any sleeping processes that could be 114 * (1) trying to send data to the pty, or (2) waiting in wait_until_sent() 115 * for the pty buffer to be drained. 116 */ 117static void pty_unthrottle(struct tty_struct * tty) 118{ 119 struct tty_struct *o_tty = tty->link; 120 121 if (!o_tty) 122 return; 123 124 if ((o_tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) && 125 o_tty->ldisc.write_wakeup) 126 (o_tty->ldisc.write_wakeup)(o_tty); 127 wake_up_interruptible(&o_tty->write_wait); 128 set_bit(TTY_THROTTLED, &tty->flags); 129} 130 131/* 132 * WSH 05/24/97: modified to 133 * (1) use space in tty->flip instead of a shared temp buffer 134 * The flip buffers aren't being used for a pty, so there's lots 135 * of space available. The buffer is protected by a per-pty 136 * semaphore that should almost never come under contention. 137 * (2) avoid redundant copying for cases where count >> receive_room 138 * N.B. Calls from user space may now return an error code instead of 139 * a count. 140 */ 141static int pty_write(struct tty_struct * tty, int from_user, 142 const unsigned char *buf, int count) 143{ 144 struct tty_struct *to = tty->link; 145 int c=0, n, room; 146 char *temp_buffer; 147 148 if (!to || tty->stopped) 149 return 0; 150 151 if (from_user) { 152 down(&tty->flip.pty_sem); 153 temp_buffer = &tty->flip.char_buf[0]; 154 while (count > 0) { 155 /* check space so we don't copy needlessly */ 156 n = to->ldisc.receive_room(to); 157 if (n > count) 158 n = count; 159 if (!n) break; 160 161 n = MIN(n, PTY_BUF_SIZE); 162 n -= copy_from_user(temp_buffer, buf, n); 163 if (!n) { 164 if (!c) 165 c = -EFAULT; 166 break; 167 } 168 169 /* check again in case the buffer filled up */ 170 room = to->ldisc.receive_room(to); 171 if (n > room) 172 n = room; 173 if (!n) break; 174 buf += n; 175 c += n; 176 count -= n; 177 to->ldisc.receive_buf(to, temp_buffer, 0, n); 178 } 179 up(&tty->flip.pty_sem); 180 } else { 181 c = to->ldisc.receive_room(to); 182 if (c > count) 183 c = count; 184 to->ldisc.receive_buf(to, buf, 0, c); 185 } 186 187 return c; 188} 189 190static int pty_write_room(struct tty_struct *tty) 191{ 192 struct tty_struct *to = tty->link; 193 194 if (!to || tty->stopped) 195 return 0; 196 197 return to->ldisc.receive_room(to); 198} 199 200/* 201 * WSH 05/24/97: Modified for asymmetric MASTER/SLAVE behavior 202 * The chars_in_buffer() value is used by the ldisc select() function 203 * to hold off writing when chars_in_buffer > WAKEUP_CHARS (== 256). 204 * The pty driver chars_in_buffer() Master/Slave must behave differently: 205 * 206 * The Master side needs to allow typed-ahead commands to accumulate 207 * while being canonicalized, so we report "our buffer" as empty until 208 * some threshold is reached, and then report the count. (Any count > 209 * WAKEUP_CHARS is regarded by select() as "full".) To avoid deadlock 210 * the count returned must be 0 if no canonical data is available to be 211 * read. (The N_TTY ldisc.chars_in_buffer now knows this.) 212 * 213 * The Slave side passes all characters in raw mode to the Master side's 214 * buffer where they can be read immediately, so in this case we can 215 * return the true count in the buffer. 216 */ 217static int pty_chars_in_buffer(struct tty_struct *tty) 218{ 219 struct tty_struct *to = tty->link; 220 int count; 221 222 if (!to || !to->ldisc.chars_in_buffer) 223 return 0; 224 225 /* The ldisc must report 0 if no characters available to be read */ 226 count = to->ldisc.chars_in_buffer(to); 227 228 if (tty->driver.subtype == PTY_TYPE_SLAVE) return count; 229 230 /* Master side driver ... if the other side's read buffer is less than 231 * half full, return 0 to allow writers to proceed; otherwise return 232 * the count. This leaves a comfortable margin to avoid overflow, 233 * and still allows half a buffer's worth of typed-ahead commands. 234 */ 235 return ((count < N_TTY_BUF_SIZE/2) ? 0 : count); 236} 237 238/* 239 * Return the device number of a Unix98 PTY (only!). This lets us open a 240 * master pty with the multi-headed ptmx device, then find out which 241 * one we got after it is open, with an ioctl. 242 */ 243#ifdef CONFIG_UNIX98_PTYS 244static int pty_get_device_number(struct tty_struct *tty, unsigned int *value) 245{ 246 unsigned int result = MINOR(tty->device) 247 - tty->driver.minor_start + tty->driver.name_base; 248 return put_user(result, value); 249} 250#endif 251 252/* Set the lock flag on a pty */ 253static int pty_set_lock(struct tty_struct *tty, int * arg) 254{ 255 int val; 256 if (get_user(val,arg)) 257 return -EFAULT; 258 if (val) 259 set_bit(TTY_PTY_LOCK, &tty->flags); 260 else 261 clear_bit(TTY_PTY_LOCK, &tty->flags); 262 return 0; 263} 264 265static int pty_bsd_ioctl(struct tty_struct *tty, struct file *file, 266 unsigned int cmd, unsigned long arg) 267{ 268 if (!tty) { 269 printk("pty_ioctl called with NULL tty!\n"); 270 return -EIO; 271 } 272 switch(cmd) { 273 case TIOCSPTLCK: /* Set PT Lock (disallow slave open) */ 274 return pty_set_lock(tty, (int *) arg); 275 } 276 return -ENOIOCTLCMD; 277} 278 279#ifdef CONFIG_UNIX98_PTYS 280static int pty_unix98_ioctl(struct tty_struct *tty, struct file *file, 281 unsigned int cmd, unsigned long arg) 282{ 283 if (!tty) { 284 printk("pty_unix98_ioctl called with NULL tty!\n"); 285 return -EIO; 286 } 287 switch(cmd) { 288 case TIOCGPTN: /* Get PT Number */ 289 return pty_get_device_number(tty, (unsigned int *)arg); 290 } 291 292 return pty_bsd_ioctl(tty,file,cmd,arg); 293} 294#endif 295 296static void pty_flush_buffer(struct tty_struct *tty) 297{ 298 struct tty_struct *to = tty->link; 299 300 if (!to) 301 return; 302 303 if (to->ldisc.flush_buffer) 304 to->ldisc.flush_buffer(to); 305 306 if (to->packet) { 307 tty->ctrl_status |= TIOCPKT_FLUSHWRITE; 308 wake_up_interruptible(&to->read_wait); 309 } 310} 311 312static int pty_open(struct tty_struct *tty, struct file * filp) 313{ 314 int retval; 315 int line; 316 struct pty_struct *pty; 317 318 retval = -ENODEV; 319 if (!tty || !tty->link) 320 goto out; 321 line = MINOR(tty->device) - tty->driver.minor_start; 322 if ((line < 0) || (line >= NR_PTYS)) 323 goto out; 324 pty = (struct pty_struct *)(tty->driver.driver_state) + line; 325 tty->driver_data = pty; 326 327 retval = -EIO; 328 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) 329 goto out; 330 if (test_bit(TTY_PTY_LOCK, &tty->link->flags)) 331 goto out; 332 if (tty->link->count != 1) 333 goto out; 334 335 clear_bit(TTY_OTHER_CLOSED, &tty->link->flags); 336 wake_up_interruptible(&pty->open_wait); 337 set_bit(TTY_THROTTLED, &tty->flags); 338 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 339 340 /* Register a slave for the master */ 341 if (tty->driver.major == PTY_MASTER_MAJOR) 342 tty_register_devfs(&tty->link->driver, 343 DEVFS_FL_CURRENT_OWNER | DEVFS_FL_WAIT, 344 tty->link->driver.minor_start + 345 MINOR(tty->device)-tty->driver.minor_start); 346 retval = 0; 347out: 348 return retval; 349} 350 351static void pty_set_termios(struct tty_struct *tty, struct termios *old_termios) 352{ 353 tty->termios->c_cflag &= ~(CSIZE | PARENB); 354 tty->termios->c_cflag |= (CS8 | CREAD); 355} 356 357int __init pty_init(void) 358{ 359 int i; 360 361 /* Traditional BSD devices */ 362 363 memset(&pty_state, 0, sizeof(pty_state)); 364 for (i = 0; i < NR_PTYS; i++) 365 init_waitqueue_head(&pty_state[i].open_wait); 366 memset(&pty_driver, 0, sizeof(struct tty_driver)); 367 pty_driver.magic = TTY_DRIVER_MAGIC; 368 pty_driver.driver_name = "pty_master"; 369#ifdef CONFIG_DEVFS_FS 370 pty_driver.name = "pty/m%d"; 371#else 372 pty_driver.name = "pty"; 373#endif 374 pty_driver.major = PTY_MASTER_MAJOR; 375 pty_driver.minor_start = 0; 376 pty_driver.num = NR_PTYS; 377 pty_driver.type = TTY_DRIVER_TYPE_PTY; 378 pty_driver.subtype = PTY_TYPE_MASTER; 379 pty_driver.init_termios = tty_std_termios; 380 pty_driver.init_termios.c_iflag = 0; 381 pty_driver.init_termios.c_oflag = 0; 382 pty_driver.init_termios.c_cflag = B38400 | CS8 | CREAD; 383 pty_driver.init_termios.c_lflag = 0; 384 pty_driver.flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW; 385 pty_driver.refcount = &pty_refcount; 386 pty_driver.table = pty_table; 387 pty_driver.termios = pty_termios; 388 pty_driver.termios_locked = pty_termios_locked; 389 pty_driver.driver_state = pty_state; 390 pty_driver.other = &pty_slave_driver; 391 392 pty_driver.open = pty_open; 393 pty_driver.close = pty_close; 394 pty_driver.write = pty_write; 395 pty_driver.write_room = pty_write_room; 396 pty_driver.flush_buffer = pty_flush_buffer; 397 pty_driver.chars_in_buffer = pty_chars_in_buffer; 398 pty_driver.unthrottle = pty_unthrottle; 399 pty_driver.set_termios = pty_set_termios; 400 401 pty_slave_driver = pty_driver; 402 pty_slave_driver.driver_name = "pty_slave"; 403 pty_slave_driver.proc_entry = 0; 404#ifdef CONFIG_DEVFS_FS 405 pty_slave_driver.name = "pty/s%d"; 406#else 407 pty_slave_driver.name = "ttyp"; 408#endif 409 pty_slave_driver.subtype = PTY_TYPE_SLAVE; 410 pty_slave_driver.major = PTY_SLAVE_MAJOR; 411 pty_slave_driver.minor_start = 0; 412 pty_slave_driver.init_termios = tty_std_termios; 413 pty_slave_driver.init_termios.c_cflag = B38400 | CS8 | CREAD; 414 /* Slave ptys are registered when their corresponding master pty 415 * is opened, and unregistered when the pair is closed. 416 */ 417 pty_slave_driver.flags |= TTY_DRIVER_NO_DEVFS; 418 pty_slave_driver.table = ttyp_table; 419 pty_slave_driver.termios = ttyp_termios; 420 pty_slave_driver.termios_locked = ttyp_termios_locked; 421 pty_slave_driver.driver_state = pty_state; 422 pty_slave_driver.other = &pty_driver; 423 424 if (tty_register_driver(&pty_driver)) 425 panic("Couldn't register pty driver"); 426 if (tty_register_driver(&pty_slave_driver)) 427 panic("Couldn't register pty slave driver"); 428 429 /* 430 * only the master pty gets this ioctl (which is why we 431 * assign it here, instead of up with the rest of the 432 * pty_driver initialization. <cananian@alumni.princeton.edu> 433 */ 434 pty_driver.ioctl = pty_bsd_ioctl; 435 436 /* Unix98 devices */ 437#ifdef CONFIG_UNIX98_PTYS 438 devfs_mk_dir (NULL, "pts", NULL); 439 printk("pty: %d Unix98 ptys configured\n", UNIX98_NR_MAJORS*NR_PTYS); 440 for ( i = 0 ; i < UNIX98_NR_MAJORS ; i++ ) { 441 int j; 442 443 ptm_driver[i] = pty_driver; 444 ptm_driver[i].name = "ptm"; 445 ptm_driver[i].proc_entry = 0; 446 ptm_driver[i].major = UNIX98_PTY_MASTER_MAJOR+i; 447 ptm_driver[i].minor_start = 0; 448 ptm_driver[i].name_base = i*NR_PTYS; 449 ptm_driver[i].num = NR_PTYS; 450 ptm_driver[i].other = &pts_driver[i]; 451 ptm_driver[i].flags |= TTY_DRIVER_NO_DEVFS; 452 ptm_driver[i].table = ptm_table[i]; 453 ptm_driver[i].termios = ptm_termios[i]; 454 ptm_driver[i].termios_locked = ptm_termios_locked[i]; 455 ptm_driver[i].driver_state = ptm_state[i]; 456 457 for (j = 0; j < NR_PTYS; j++) 458 init_waitqueue_head(&ptm_state[i][j].open_wait); 459 460 pts_driver[i] = pty_slave_driver; 461#ifdef CONFIG_DEVFS_FS 462 pts_driver[i].name = "pts/%d"; 463#else 464 pts_driver[i].name = "pts"; 465#endif 466 pts_driver[i].proc_entry = 0; 467 pts_driver[i].major = UNIX98_PTY_SLAVE_MAJOR+i; 468 pts_driver[i].minor_start = 0; 469 pts_driver[i].name_base = i*NR_PTYS; 470 pts_driver[i].num = ptm_driver[i].num; 471 pts_driver[i].other = &ptm_driver[i]; 472 pts_driver[i].table = pts_table[i]; 473 pts_driver[i].termios = pts_termios[i]; 474 pts_driver[i].termios_locked = pts_termios_locked[i]; 475 pts_driver[i].driver_state = ptm_state[i]; 476 477 ptm_driver[i].ioctl = pty_unix98_ioctl; 478 479 if (tty_register_driver(&ptm_driver[i])) 480 panic("Couldn't register Unix98 ptm driver major %d", 481 ptm_driver[i].major); 482 if (tty_register_driver(&pts_driver[i])) 483 panic("Couldn't register Unix98 pts driver major %d", 484 pts_driver[i].major); 485 } 486#endif 487 return 0; 488} 489