1/* 2 * n_tty.c --- implements the N_TTY line discipline. 3 * 4 * This code used to be in tty_io.c, but things are getting hairy 5 * enough that it made sense to split things off. (The N_TTY 6 * processing has changed so much that it's hardly recognizable, 7 * anyway...) 8 * 9 * Note that the open routine for N_TTY is guaranteed never to return 10 * an error. This is because Linux will fall back to setting a line 11 * to N_TTY if it can not switch to any other line discipline. 12 * 13 * Written by Theodore Ts'o, Copyright 1994. 14 * 15 * This file also contains code originally written by Linus Torvalds, 16 * Copyright 1991, 1992, 1993, and by Julian Cowley, Copyright 1994. 17 * 18 * This file may be redistributed under the terms of the GNU General Public 19 * License. 20 * 21 * Reduced memory usage for older ARM systems - Russell King. 22 * 23 * 2000/01/20 Fixed SMP locking on put_tty_queue using bits of 24 * the patch by Andrew J. Kroll <ag784@freenet.buffalo.edu> 25 * who actually finally proved there really was a race. 26 * 27 * 2002/03/18 Implemented n_tty_wakeup to send SIGIO POLL_OUTs to 28 * waiting writing processes-Sapan Bhatia <sapan@corewars.org>. 29 * Also fixed a bug in BLOCKING mode where n_tty_write returns 30 * EAGAIN 31 */ 32 33#include <linux/types.h> 34#include <linux/major.h> 35#include <linux/errno.h> 36#include <linux/signal.h> 37#include <linux/fcntl.h> 38#include <linux/sched.h> 39#include <linux/interrupt.h> 40#include <linux/tty.h> 41#include <linux/timer.h> 42#include <linux/ctype.h> 43#include <linux/mm.h> 44#include <linux/string.h> 45#include <linux/slab.h> 46#include <linux/poll.h> 47#include <linux/bitops.h> 48#include <linux/audit.h> 49#include <linux/file.h> 50#include <linux/uaccess.h> 51#include <linux/module.h> 52#include <linux/ratelimit.h> 53#include <linux/vmalloc.h> 54 55 56/* number of characters left in xmit buffer before select has we have room */ 57#define WAKEUP_CHARS 256 58 59/* 60 * This defines the low- and high-watermarks for throttling and 61 * unthrottling the TTY driver. These watermarks are used for 62 * controlling the space in the read buffer. 63 */ 64#define TTY_THRESHOLD_THROTTLE 128 /* now based on remaining room */ 65#define TTY_THRESHOLD_UNTHROTTLE 128 66 67/* 68 * Special byte codes used in the echo buffer to represent operations 69 * or special handling of characters. Bytes in the echo buffer that 70 * are not part of such special blocks are treated as normal character 71 * codes. 72 */ 73#define ECHO_OP_START 0xff 74#define ECHO_OP_MOVE_BACK_COL 0x80 75#define ECHO_OP_SET_CANON_COL 0x81 76#define ECHO_OP_ERASE_TAB 0x82 77 78#define ECHO_COMMIT_WATERMARK 256 79#define ECHO_BLOCK 256 80#define ECHO_DISCARD_WATERMARK N_TTY_BUF_SIZE - (ECHO_BLOCK + 32) 81 82 83#undef N_TTY_TRACE 84#ifdef N_TTY_TRACE 85# define n_tty_trace(f, args...) trace_printk(f, ##args) 86#else 87# define n_tty_trace(f, args...) 88#endif 89 90struct n_tty_data { 91 /* producer-published */ 92 size_t read_head; 93 size_t commit_head; 94 size_t canon_head; 95 size_t echo_head; 96 size_t echo_commit; 97 size_t echo_mark; 98 DECLARE_BITMAP(char_map, 256); 99 100 /* private to n_tty_receive_overrun (single-threaded) */ 101 unsigned long overrun_time; 102 int num_overrun; 103 104 /* non-atomic */ 105 bool no_room; 106 107 /* must hold exclusive termios_rwsem to reset these */ 108 unsigned char lnext:1, erasing:1, raw:1, real_raw:1, icanon:1; 109 unsigned char push:1; 110 111 /* shared by producer and consumer */ 112 char read_buf[N_TTY_BUF_SIZE]; 113 DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE); 114 unsigned char echo_buf[N_TTY_BUF_SIZE]; 115 116 int minimum_to_wake; 117 118 /* consumer-published */ 119 size_t read_tail; 120 size_t line_start; 121 122 /* protected by output lock */ 123 unsigned int column; 124 unsigned int canon_column; 125 size_t echo_tail; 126 127 struct mutex atomic_read_lock; 128 struct mutex output_lock; 129}; 130 131static inline size_t read_cnt(struct n_tty_data *ldata) 132{ 133 return ldata->read_head - ldata->read_tail; 134} 135 136static inline unsigned char read_buf(struct n_tty_data *ldata, size_t i) 137{ 138 return ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)]; 139} 140 141static inline unsigned char *read_buf_addr(struct n_tty_data *ldata, size_t i) 142{ 143 return &ldata->read_buf[i & (N_TTY_BUF_SIZE - 1)]; 144} 145 146static inline unsigned char echo_buf(struct n_tty_data *ldata, size_t i) 147{ 148 return ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)]; 149} 150 151static inline unsigned char *echo_buf_addr(struct n_tty_data *ldata, size_t i) 152{ 153 return &ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)]; 154} 155 156static inline int tty_put_user(struct tty_struct *tty, unsigned char x, 157 unsigned char __user *ptr) 158{ 159 struct n_tty_data *ldata = tty->disc_data; 160 161 tty_audit_add_data(tty, &x, 1, ldata->icanon); 162 return put_user(x, ptr); 163} 164 165static inline int tty_copy_to_user(struct tty_struct *tty, 166 void __user *to, 167 const void *from, 168 unsigned long n) 169{ 170 struct n_tty_data *ldata = tty->disc_data; 171 172 tty_audit_add_data(tty, from, n, ldata->icanon); 173 return copy_to_user(to, from, n); 174} 175 176/** 177 * n_tty_kick_worker - start input worker (if required) 178 * @tty: terminal 179 * 180 * Re-schedules the flip buffer work if it may have stopped 181 * 182 * Caller holds exclusive termios_rwsem 183 * or 184 * n_tty_read()/consumer path: 185 * holds non-exclusive termios_rwsem 186 */ 187 188static void n_tty_kick_worker(struct tty_struct *tty) 189{ 190 struct n_tty_data *ldata = tty->disc_data; 191 192 /* Did the input worker stop? Restart it */ 193 if (unlikely(ldata->no_room)) { 194 ldata->no_room = 0; 195 196 WARN_RATELIMIT(tty->port->itty == NULL, 197 "scheduling with invalid itty\n"); 198 /* see if ldisc has been killed - if so, this means that 199 * even though the ldisc has been halted and ->buf.work 200 * cancelled, ->buf.work is about to be rescheduled 201 */ 202 WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags), 203 "scheduling buffer work for halted ldisc\n"); 204 queue_work(system_unbound_wq, &tty->port->buf.work); 205 } 206} 207 208static ssize_t chars_in_buffer(struct tty_struct *tty) 209{ 210 struct n_tty_data *ldata = tty->disc_data; 211 ssize_t n = 0; 212 213 if (!ldata->icanon) 214 n = ldata->commit_head - ldata->read_tail; 215 else 216 n = ldata->canon_head - ldata->read_tail; 217 return n; 218} 219 220/** 221 * n_tty_write_wakeup - asynchronous I/O notifier 222 * @tty: tty device 223 * 224 * Required for the ptys, serial driver etc. since processes 225 * that attach themselves to the master and rely on ASYNC 226 * IO must be woken up 227 */ 228 229static void n_tty_write_wakeup(struct tty_struct *tty) 230{ 231 if (tty->fasync && test_and_clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags)) 232 kill_fasync(&tty->fasync, SIGIO, POLL_OUT); 233} 234 235static void n_tty_check_throttle(struct tty_struct *tty) 236{ 237 struct n_tty_data *ldata = tty->disc_data; 238 239 /* 240 * Check the remaining room for the input canonicalization 241 * mode. We don't want to throttle the driver if we're in 242 * canonical mode and don't have a newline yet! 243 */ 244 if (ldata->icanon && ldata->canon_head == ldata->read_tail) 245 return; 246 247 while (1) { 248 int throttled; 249 tty_set_flow_change(tty, TTY_THROTTLE_SAFE); 250 if (N_TTY_BUF_SIZE - read_cnt(ldata) >= TTY_THRESHOLD_THROTTLE) 251 break; 252 throttled = tty_throttle_safe(tty); 253 if (!throttled) 254 break; 255 } 256 __tty_set_flow_change(tty, 0); 257} 258 259static void n_tty_check_unthrottle(struct tty_struct *tty) 260{ 261 if (tty->driver->type == TTY_DRIVER_TYPE_PTY) { 262 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE) 263 return; 264 if (!tty->count) 265 return; 266 n_tty_kick_worker(tty); 267 tty_wakeup(tty->link); 268 return; 269 } 270 271 /* If there is enough space in the read buffer now, let the 272 * low-level driver know. We use chars_in_buffer() to 273 * check the buffer, as it now knows about canonical mode. 274 * Otherwise, if the driver is throttled and the line is 275 * longer than TTY_THRESHOLD_UNTHROTTLE in canonical mode, 276 * we won't get any more characters. 277 */ 278 279 while (1) { 280 int unthrottled; 281 tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE); 282 if (chars_in_buffer(tty) > TTY_THRESHOLD_UNTHROTTLE) 283 break; 284 if (!tty->count) 285 break; 286 n_tty_kick_worker(tty); 287 unthrottled = tty_unthrottle_safe(tty); 288 if (!unthrottled) 289 break; 290 } 291 __tty_set_flow_change(tty, 0); 292} 293 294/** 295 * put_tty_queue - add character to tty 296 * @c: character 297 * @ldata: n_tty data 298 * 299 * Add a character to the tty read_buf queue. 300 * 301 * n_tty_receive_buf()/producer path: 302 * caller holds non-exclusive termios_rwsem 303 */ 304 305static inline void put_tty_queue(unsigned char c, struct n_tty_data *ldata) 306{ 307 *read_buf_addr(ldata, ldata->read_head) = c; 308 ldata->read_head++; 309} 310 311/** 312 * reset_buffer_flags - reset buffer state 313 * @tty: terminal to reset 314 * 315 * Reset the read buffer counters and clear the flags. 316 * Called from n_tty_open() and n_tty_flush_buffer(). 317 * 318 * Locking: caller holds exclusive termios_rwsem 319 * (or locking is not required) 320 */ 321 322static void reset_buffer_flags(struct n_tty_data *ldata) 323{ 324 ldata->read_head = ldata->canon_head = ldata->read_tail = 0; 325 ldata->echo_head = ldata->echo_tail = ldata->echo_commit = 0; 326 ldata->commit_head = 0; 327 ldata->echo_mark = 0; 328 ldata->line_start = 0; 329 330 ldata->erasing = 0; 331 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE); 332 ldata->push = 0; 333} 334 335static void n_tty_packet_mode_flush(struct tty_struct *tty) 336{ 337 unsigned long flags; 338 339 if (tty->link->packet) { 340 spin_lock_irqsave(&tty->ctrl_lock, flags); 341 tty->ctrl_status |= TIOCPKT_FLUSHREAD; 342 spin_unlock_irqrestore(&tty->ctrl_lock, flags); 343 wake_up_interruptible(&tty->link->read_wait); 344 } 345} 346 347/** 348 * n_tty_flush_buffer - clean input queue 349 * @tty: terminal device 350 * 351 * Flush the input buffer. Called when the tty layer wants the 352 * buffer flushed (eg at hangup) or when the N_TTY line discipline 353 * internally has to clean the pending queue (for example some signals). 354 * 355 * Holds termios_rwsem to exclude producer/consumer while 356 * buffer indices are reset. 357 * 358 * Locking: ctrl_lock, exclusive termios_rwsem 359 */ 360 361static void n_tty_flush_buffer(struct tty_struct *tty) 362{ 363 down_write(&tty->termios_rwsem); 364 reset_buffer_flags(tty->disc_data); 365 n_tty_kick_worker(tty); 366 367 if (tty->link) 368 n_tty_packet_mode_flush(tty); 369 up_write(&tty->termios_rwsem); 370} 371 372/** 373 * n_tty_chars_in_buffer - report available bytes 374 * @tty: tty device 375 * 376 * Report the number of characters buffered to be delivered to user 377 * at this instant in time. 378 * 379 * Locking: exclusive termios_rwsem 380 */ 381 382static ssize_t n_tty_chars_in_buffer(struct tty_struct *tty) 383{ 384 ssize_t n; 385 386 WARN_ONCE(1, "%s is deprecated and scheduled for removal.", __func__); 387 388 down_write(&tty->termios_rwsem); 389 n = chars_in_buffer(tty); 390 up_write(&tty->termios_rwsem); 391 return n; 392} 393 394/** 395 * is_utf8_continuation - utf8 multibyte check 396 * @c: byte to check 397 * 398 * Returns true if the utf8 character 'c' is a multibyte continuation 399 * character. We use this to correctly compute the on screen size 400 * of the character when printing 401 */ 402 403static inline int is_utf8_continuation(unsigned char c) 404{ 405 return (c & 0xc0) == 0x80; 406} 407 408/** 409 * is_continuation - multibyte check 410 * @c: byte to check 411 * 412 * Returns true if the utf8 character 'c' is a multibyte continuation 413 * character and the terminal is in unicode mode. 414 */ 415 416static inline int is_continuation(unsigned char c, struct tty_struct *tty) 417{ 418 return I_IUTF8(tty) && is_utf8_continuation(c); 419} 420 421/** 422 * do_output_char - output one character 423 * @c: character (or partial unicode symbol) 424 * @tty: terminal device 425 * @space: space available in tty driver write buffer 426 * 427 * This is a helper function that handles one output character 428 * (including special characters like TAB, CR, LF, etc.), 429 * doing OPOST processing and putting the results in the 430 * tty driver's write buffer. 431 * 432 * Note that Linux currently ignores TABDLY, CRDLY, VTDLY, FFDLY 433 * and NLDLY. They simply aren't relevant in the world today. 434 * If you ever need them, add them here. 435 * 436 * Returns the number of bytes of buffer space used or -1 if 437 * no space left. 438 * 439 * Locking: should be called under the output_lock to protect 440 * the column state and space left in the buffer 441 */ 442 443static int do_output_char(unsigned char c, struct tty_struct *tty, int space) 444{ 445 struct n_tty_data *ldata = tty->disc_data; 446 int spaces; 447 448 if (!space) 449 return -1; 450 451 switch (c) { 452 case '\n': 453 if (O_ONLRET(tty)) 454 ldata->column = 0; 455 if (O_ONLCR(tty)) { 456 if (space < 2) 457 return -1; 458 ldata->canon_column = ldata->column = 0; 459 tty->ops->write(tty, "\r\n", 2); 460 return 2; 461 } 462 ldata->canon_column = ldata->column; 463 break; 464 case '\r': 465 if (O_ONOCR(tty) && ldata->column == 0) 466 return 0; 467 if (O_OCRNL(tty)) { 468 c = '\n'; 469 if (O_ONLRET(tty)) 470 ldata->canon_column = ldata->column = 0; 471 break; 472 } 473 ldata->canon_column = ldata->column = 0; 474 break; 475 case '\t': 476 spaces = 8 - (ldata->column & 7); 477 if (O_TABDLY(tty) == XTABS) { 478 if (space < spaces) 479 return -1; 480 ldata->column += spaces; 481 tty->ops->write(tty, " ", spaces); 482 return spaces; 483 } 484 ldata->column += spaces; 485 break; 486 case '\b': 487 if (ldata->column > 0) 488 ldata->column--; 489 break; 490 default: 491 if (!iscntrl(c)) { 492 if (O_OLCUC(tty)) 493 c = toupper(c); 494 if (!is_continuation(c, tty)) 495 ldata->column++; 496 } 497 break; 498 } 499 500 tty_put_char(tty, c); 501 return 1; 502} 503 504/** 505 * process_output - output post processor 506 * @c: character (or partial unicode symbol) 507 * @tty: terminal device 508 * 509 * Output one character with OPOST processing. 510 * Returns -1 when the output device is full and the character 511 * must be retried. 512 * 513 * Locking: output_lock to protect column state and space left 514 * (also, this is called from n_tty_write under the 515 * tty layer write lock) 516 */ 517 518static int process_output(unsigned char c, struct tty_struct *tty) 519{ 520 struct n_tty_data *ldata = tty->disc_data; 521 int space, retval; 522 523 mutex_lock(&ldata->output_lock); 524 525 space = tty_write_room(tty); 526 retval = do_output_char(c, tty, space); 527 528 mutex_unlock(&ldata->output_lock); 529 if (retval < 0) 530 return -1; 531 else 532 return 0; 533} 534 535/** 536 * process_output_block - block post processor 537 * @tty: terminal device 538 * @buf: character buffer 539 * @nr: number of bytes to output 540 * 541 * Output a block of characters with OPOST processing. 542 * Returns the number of characters output. 543 * 544 * This path is used to speed up block console writes, among other 545 * things when processing blocks of output data. It handles only 546 * the simple cases normally found and helps to generate blocks of 547 * symbols for the console driver and thus improve performance. 548 * 549 * Locking: output_lock to protect column state and space left 550 * (also, this is called from n_tty_write under the 551 * tty layer write lock) 552 */ 553 554static ssize_t process_output_block(struct tty_struct *tty, 555 const unsigned char *buf, unsigned int nr) 556{ 557 struct n_tty_data *ldata = tty->disc_data; 558 int space; 559 int i; 560 const unsigned char *cp; 561 562 mutex_lock(&ldata->output_lock); 563 564 space = tty_write_room(tty); 565 if (!space) { 566 mutex_unlock(&ldata->output_lock); 567 return 0; 568 } 569 if (nr > space) 570 nr = space; 571 572 for (i = 0, cp = buf; i < nr; i++, cp++) { 573 unsigned char c = *cp; 574 575 switch (c) { 576 case '\n': 577 if (O_ONLRET(tty)) 578 ldata->column = 0; 579 if (O_ONLCR(tty)) 580 goto break_out; 581 ldata->canon_column = ldata->column; 582 break; 583 case '\r': 584 if (O_ONOCR(tty) && ldata->column == 0) 585 goto break_out; 586 if (O_OCRNL(tty)) 587 goto break_out; 588 ldata->canon_column = ldata->column = 0; 589 break; 590 case '\t': 591 goto break_out; 592 case '\b': 593 if (ldata->column > 0) 594 ldata->column--; 595 break; 596 default: 597 if (!iscntrl(c)) { 598 if (O_OLCUC(tty)) 599 goto break_out; 600 if (!is_continuation(c, tty)) 601 ldata->column++; 602 } 603 break; 604 } 605 } 606break_out: 607 i = tty->ops->write(tty, buf, i); 608 609 mutex_unlock(&ldata->output_lock); 610 return i; 611} 612 613/** 614 * process_echoes - write pending echo characters 615 * @tty: terminal device 616 * 617 * Write previously buffered echo (and other ldisc-generated) 618 * characters to the tty. 619 * 620 * Characters generated by the ldisc (including echoes) need to 621 * be buffered because the driver's write buffer can fill during 622 * heavy program output. Echoing straight to the driver will 623 * often fail under these conditions, causing lost characters and 624 * resulting mismatches of ldisc state information. 625 * 626 * Since the ldisc state must represent the characters actually sent 627 * to the driver at the time of the write, operations like certain 628 * changes in column state are also saved in the buffer and executed 629 * here. 630 * 631 * A circular fifo buffer is used so that the most recent characters 632 * are prioritized. Also, when control characters are echoed with a 633 * prefixed "^", the pair is treated atomically and thus not separated. 634 * 635 * Locking: callers must hold output_lock 636 */ 637 638static size_t __process_echoes(struct tty_struct *tty) 639{ 640 struct n_tty_data *ldata = tty->disc_data; 641 int space, old_space; 642 size_t tail; 643 unsigned char c; 644 645 old_space = space = tty_write_room(tty); 646 647 tail = ldata->echo_tail; 648 while (ldata->echo_commit != tail) { 649 c = echo_buf(ldata, tail); 650 if (c == ECHO_OP_START) { 651 unsigned char op; 652 int no_space_left = 0; 653 654 /* 655 * If the buffer byte is the start of a multi-byte 656 * operation, get the next byte, which is either the 657 * op code or a control character value. 658 */ 659 op = echo_buf(ldata, tail + 1); 660 661 switch (op) { 662 unsigned int num_chars, num_bs; 663 664 case ECHO_OP_ERASE_TAB: 665 num_chars = echo_buf(ldata, tail + 2); 666 667 /* 668 * Determine how many columns to go back 669 * in order to erase the tab. 670 * This depends on the number of columns 671 * used by other characters within the tab 672 * area. If this (modulo 8) count is from 673 * the start of input rather than from a 674 * previous tab, we offset by canon column. 675 * Otherwise, tab spacing is normal. 676 */ 677 if (!(num_chars & 0x80)) 678 num_chars += ldata->canon_column; 679 num_bs = 8 - (num_chars & 7); 680 681 if (num_bs > space) { 682 no_space_left = 1; 683 break; 684 } 685 space -= num_bs; 686 while (num_bs--) { 687 tty_put_char(tty, '\b'); 688 if (ldata->column > 0) 689 ldata->column--; 690 } 691 tail += 3; 692 break; 693 694 case ECHO_OP_SET_CANON_COL: 695 ldata->canon_column = ldata->column; 696 tail += 2; 697 break; 698 699 case ECHO_OP_MOVE_BACK_COL: 700 if (ldata->column > 0) 701 ldata->column--; 702 tail += 2; 703 break; 704 705 case ECHO_OP_START: 706 /* This is an escaped echo op start code */ 707 if (!space) { 708 no_space_left = 1; 709 break; 710 } 711 tty_put_char(tty, ECHO_OP_START); 712 ldata->column++; 713 space--; 714 tail += 2; 715 break; 716 717 default: 718 /* 719 * If the op is not a special byte code, 720 * it is a ctrl char tagged to be echoed 721 * as "^X" (where X is the letter 722 * representing the control char). 723 * Note that we must ensure there is 724 * enough space for the whole ctrl pair. 725 * 726 */ 727 if (space < 2) { 728 no_space_left = 1; 729 break; 730 } 731 tty_put_char(tty, '^'); 732 tty_put_char(tty, op ^ 0100); 733 ldata->column += 2; 734 space -= 2; 735 tail += 2; 736 } 737 738 if (no_space_left) 739 break; 740 } else { 741 if (O_OPOST(tty)) { 742 int retval = do_output_char(c, tty, space); 743 if (retval < 0) 744 break; 745 space -= retval; 746 } else { 747 if (!space) 748 break; 749 tty_put_char(tty, c); 750 space -= 1; 751 } 752 tail += 1; 753 } 754 } 755 756 /* If the echo buffer is nearly full (so that the possibility exists 757 * of echo overrun before the next commit), then discard enough 758 * data at the tail to prevent a subsequent overrun */ 759 while (ldata->echo_commit - tail >= ECHO_DISCARD_WATERMARK) { 760 if (echo_buf(ldata, tail) == ECHO_OP_START) { 761 if (echo_buf(ldata, tail + 1) == ECHO_OP_ERASE_TAB) 762 tail += 3; 763 else 764 tail += 2; 765 } else 766 tail++; 767 } 768 769 ldata->echo_tail = tail; 770 return old_space - space; 771} 772 773static void commit_echoes(struct tty_struct *tty) 774{ 775 struct n_tty_data *ldata = tty->disc_data; 776 size_t nr, old, echoed; 777 size_t head; 778 779 head = ldata->echo_head; 780 ldata->echo_mark = head; 781 old = ldata->echo_commit - ldata->echo_tail; 782 783 /* Process committed echoes if the accumulated # of bytes 784 * is over the threshold (and try again each time another 785 * block is accumulated) */ 786 nr = head - ldata->echo_tail; 787 if (nr < ECHO_COMMIT_WATERMARK || (nr % ECHO_BLOCK > old % ECHO_BLOCK)) 788 return; 789 790 mutex_lock(&ldata->output_lock); 791 ldata->echo_commit = head; 792 echoed = __process_echoes(tty); 793 mutex_unlock(&ldata->output_lock); 794 795 if (echoed && tty->ops->flush_chars) 796 tty->ops->flush_chars(tty); 797} 798 799static void process_echoes(struct tty_struct *tty) 800{ 801 struct n_tty_data *ldata = tty->disc_data; 802 size_t echoed; 803 804 if (ldata->echo_mark == ldata->echo_tail) 805 return; 806 807 mutex_lock(&ldata->output_lock); 808 ldata->echo_commit = ldata->echo_mark; 809 echoed = __process_echoes(tty); 810 mutex_unlock(&ldata->output_lock); 811 812 if (echoed && tty->ops->flush_chars) 813 tty->ops->flush_chars(tty); 814} 815 816/* NB: echo_mark and echo_head should be equivalent here */ 817static void flush_echoes(struct tty_struct *tty) 818{ 819 struct n_tty_data *ldata = tty->disc_data; 820 821 if ((!L_ECHO(tty) && !L_ECHONL(tty)) || 822 ldata->echo_commit == ldata->echo_head) 823 return; 824 825 mutex_lock(&ldata->output_lock); 826 ldata->echo_commit = ldata->echo_head; 827 __process_echoes(tty); 828 mutex_unlock(&ldata->output_lock); 829} 830 831/** 832 * add_echo_byte - add a byte to the echo buffer 833 * @c: unicode byte to echo 834 * @ldata: n_tty data 835 * 836 * Add a character or operation byte to the echo buffer. 837 */ 838 839static inline void add_echo_byte(unsigned char c, struct n_tty_data *ldata) 840{ 841 *echo_buf_addr(ldata, ldata->echo_head++) = c; 842} 843 844/** 845 * echo_move_back_col - add operation to move back a column 846 * @ldata: n_tty data 847 * 848 * Add an operation to the echo buffer to move back one column. 849 */ 850 851static void echo_move_back_col(struct n_tty_data *ldata) 852{ 853 add_echo_byte(ECHO_OP_START, ldata); 854 add_echo_byte(ECHO_OP_MOVE_BACK_COL, ldata); 855} 856 857/** 858 * echo_set_canon_col - add operation to set the canon column 859 * @ldata: n_tty data 860 * 861 * Add an operation to the echo buffer to set the canon column 862 * to the current column. 863 */ 864 865static void echo_set_canon_col(struct n_tty_data *ldata) 866{ 867 add_echo_byte(ECHO_OP_START, ldata); 868 add_echo_byte(ECHO_OP_SET_CANON_COL, ldata); 869} 870 871/** 872 * echo_erase_tab - add operation to erase a tab 873 * @num_chars: number of character columns already used 874 * @after_tab: true if num_chars starts after a previous tab 875 * @ldata: n_tty data 876 * 877 * Add an operation to the echo buffer to erase a tab. 878 * 879 * Called by the eraser function, which knows how many character 880 * columns have been used since either a previous tab or the start 881 * of input. This information will be used later, along with 882 * canon column (if applicable), to go back the correct number 883 * of columns. 884 */ 885 886static void echo_erase_tab(unsigned int num_chars, int after_tab, 887 struct n_tty_data *ldata) 888{ 889 add_echo_byte(ECHO_OP_START, ldata); 890 add_echo_byte(ECHO_OP_ERASE_TAB, ldata); 891 892 /* We only need to know this modulo 8 (tab spacing) */ 893 num_chars &= 7; 894 895 /* Set the high bit as a flag if num_chars is after a previous tab */ 896 if (after_tab) 897 num_chars |= 0x80; 898 899 add_echo_byte(num_chars, ldata); 900} 901 902/** 903 * echo_char_raw - echo a character raw 904 * @c: unicode byte to echo 905 * @tty: terminal device 906 * 907 * Echo user input back onto the screen. This must be called only when 908 * L_ECHO(tty) is true. Called from the driver receive_buf path. 909 * 910 * This variant does not treat control characters specially. 911 */ 912 913static void echo_char_raw(unsigned char c, struct n_tty_data *ldata) 914{ 915 if (c == ECHO_OP_START) { 916 add_echo_byte(ECHO_OP_START, ldata); 917 add_echo_byte(ECHO_OP_START, ldata); 918 } else { 919 add_echo_byte(c, ldata); 920 } 921} 922 923/** 924 * echo_char - echo a character 925 * @c: unicode byte to echo 926 * @tty: terminal device 927 * 928 * Echo user input back onto the screen. This must be called only when 929 * L_ECHO(tty) is true. Called from the driver receive_buf path. 930 * 931 * This variant tags control characters to be echoed as "^X" 932 * (where X is the letter representing the control char). 933 */ 934 935static void echo_char(unsigned char c, struct tty_struct *tty) 936{ 937 struct n_tty_data *ldata = tty->disc_data; 938 939 if (c == ECHO_OP_START) { 940 add_echo_byte(ECHO_OP_START, ldata); 941 add_echo_byte(ECHO_OP_START, ldata); 942 } else { 943 if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') 944 add_echo_byte(ECHO_OP_START, ldata); 945 add_echo_byte(c, ldata); 946 } 947} 948 949/** 950 * finish_erasing - complete erase 951 * @ldata: n_tty data 952 */ 953 954static inline void finish_erasing(struct n_tty_data *ldata) 955{ 956 if (ldata->erasing) { 957 echo_char_raw('/', ldata); 958 ldata->erasing = 0; 959 } 960} 961 962/** 963 * eraser - handle erase function 964 * @c: character input 965 * @tty: terminal device 966 * 967 * Perform erase and necessary output when an erase character is 968 * present in the stream from the driver layer. Handles the complexities 969 * of UTF-8 multibyte symbols. 970 * 971 * n_tty_receive_buf()/producer path: 972 * caller holds non-exclusive termios_rwsem 973 */ 974 975static void eraser(unsigned char c, struct tty_struct *tty) 976{ 977 struct n_tty_data *ldata = tty->disc_data; 978 enum { ERASE, WERASE, KILL } kill_type; 979 size_t head; 980 size_t cnt; 981 int seen_alnums; 982 983 if (ldata->read_head == ldata->canon_head) { 984 /* process_output('\a', tty); */ /* what do you think? */ 985 return; 986 } 987 if (c == ERASE_CHAR(tty)) 988 kill_type = ERASE; 989 else if (c == WERASE_CHAR(tty)) 990 kill_type = WERASE; 991 else { 992 if (!L_ECHO(tty)) { 993 ldata->read_head = ldata->canon_head; 994 return; 995 } 996 if (!L_ECHOK(tty) || !L_ECHOKE(tty) || !L_ECHOE(tty)) { 997 ldata->read_head = ldata->canon_head; 998 finish_erasing(ldata); 999 echo_char(KILL_CHAR(tty), tty); 1000 /* Add a newline if ECHOK is on and ECHOKE is off. */ 1001 if (L_ECHOK(tty)) 1002 echo_char_raw('\n', ldata); 1003 return; 1004 } 1005 kill_type = KILL; 1006 } 1007 1008 seen_alnums = 0; 1009 while (ldata->read_head != ldata->canon_head) { 1010 head = ldata->read_head; 1011 1012 /* erase a single possibly multibyte character */ 1013 do { 1014 head--; 1015 c = read_buf(ldata, head); 1016 } while (is_continuation(c, tty) && head != ldata->canon_head); 1017 1018 /* do not partially erase */ 1019 if (is_continuation(c, tty)) 1020 break; 1021 1022 if (kill_type == WERASE) { 1023 /* Equivalent to BSD's ALTWERASE. */ 1024 if (isalnum(c) || c == '_') 1025 seen_alnums++; 1026 else if (seen_alnums) 1027 break; 1028 } 1029 cnt = ldata->read_head - head; 1030 ldata->read_head = head; 1031 if (L_ECHO(tty)) { 1032 if (L_ECHOPRT(tty)) { 1033 if (!ldata->erasing) { 1034 echo_char_raw('\\', ldata); 1035 ldata->erasing = 1; 1036 } 1037 /* if cnt > 1, output a multi-byte character */ 1038 echo_char(c, tty); 1039 while (--cnt > 0) { 1040 head++; 1041 echo_char_raw(read_buf(ldata, head), ldata); 1042 echo_move_back_col(ldata); 1043 } 1044 } else if (kill_type == ERASE && !L_ECHOE(tty)) { 1045 echo_char(ERASE_CHAR(tty), tty); 1046 } else if (c == '\t') { 1047 unsigned int num_chars = 0; 1048 int after_tab = 0; 1049 size_t tail = ldata->read_head; 1050 1051 /* 1052 * Count the columns used for characters 1053 * since the start of input or after a 1054 * previous tab. 1055 * This info is used to go back the correct 1056 * number of columns. 1057 */ 1058 while (tail != ldata->canon_head) { 1059 tail--; 1060 c = read_buf(ldata, tail); 1061 if (c == '\t') { 1062 after_tab = 1; 1063 break; 1064 } else if (iscntrl(c)) { 1065 if (L_ECHOCTL(tty)) 1066 num_chars += 2; 1067 } else if (!is_continuation(c, tty)) { 1068 num_chars++; 1069 } 1070 } 1071 echo_erase_tab(num_chars, after_tab, ldata); 1072 } else { 1073 if (iscntrl(c) && L_ECHOCTL(tty)) { 1074 echo_char_raw('\b', ldata); 1075 echo_char_raw(' ', ldata); 1076 echo_char_raw('\b', ldata); 1077 } 1078 if (!iscntrl(c) || L_ECHOCTL(tty)) { 1079 echo_char_raw('\b', ldata); 1080 echo_char_raw(' ', ldata); 1081 echo_char_raw('\b', ldata); 1082 } 1083 } 1084 } 1085 if (kill_type == ERASE) 1086 break; 1087 } 1088 if (ldata->read_head == ldata->canon_head && L_ECHO(tty)) 1089 finish_erasing(ldata); 1090} 1091 1092/** 1093 * isig - handle the ISIG optio 1094 * @sig: signal 1095 * @tty: terminal 1096 * 1097 * Called when a signal is being sent due to terminal input. 1098 * Called from the driver receive_buf path so serialized. 1099 * 1100 * Performs input and output flush if !NOFLSH. In this context, the echo 1101 * buffer is 'output'. The signal is processed first to alert any current 1102 * readers or writers to discontinue and exit their i/o loops. 1103 * 1104 * Locking: ctrl_lock 1105 */ 1106 1107static void __isig(int sig, struct tty_struct *tty) 1108{ 1109 struct pid *tty_pgrp = tty_get_pgrp(tty); 1110 if (tty_pgrp) { 1111 kill_pgrp(tty_pgrp, sig, 1); 1112 put_pid(tty_pgrp); 1113 } 1114} 1115 1116static void isig(int sig, struct tty_struct *tty) 1117{ 1118 struct n_tty_data *ldata = tty->disc_data; 1119 1120 if (L_NOFLSH(tty)) { 1121 /* signal only */ 1122 __isig(sig, tty); 1123 1124 } else { /* signal and flush */ 1125 up_read(&tty->termios_rwsem); 1126 down_write(&tty->termios_rwsem); 1127 1128 __isig(sig, tty); 1129 1130 /* clear echo buffer */ 1131 mutex_lock(&ldata->output_lock); 1132 ldata->echo_head = ldata->echo_tail = 0; 1133 ldata->echo_mark = ldata->echo_commit = 0; 1134 mutex_unlock(&ldata->output_lock); 1135 1136 /* clear output buffer */ 1137 tty_driver_flush_buffer(tty); 1138 1139 /* clear input buffer */ 1140 reset_buffer_flags(tty->disc_data); 1141 1142 /* notify pty master of flush */ 1143 if (tty->link) 1144 n_tty_packet_mode_flush(tty); 1145 1146 up_write(&tty->termios_rwsem); 1147 down_read(&tty->termios_rwsem); 1148 } 1149} 1150 1151/** 1152 * n_tty_receive_break - handle break 1153 * @tty: terminal 1154 * 1155 * An RS232 break event has been hit in the incoming bitstream. This 1156 * can cause a variety of events depending upon the termios settings. 1157 * 1158 * n_tty_receive_buf()/producer path: 1159 * caller holds non-exclusive termios_rwsem 1160 * 1161 * Note: may get exclusive termios_rwsem if flushing input buffer 1162 */ 1163 1164static void n_tty_receive_break(struct tty_struct *tty) 1165{ 1166 struct n_tty_data *ldata = tty->disc_data; 1167 1168 if (I_IGNBRK(tty)) 1169 return; 1170 if (I_BRKINT(tty)) { 1171 isig(SIGINT, tty); 1172 return; 1173 } 1174 if (I_PARMRK(tty)) { 1175 put_tty_queue('\377', ldata); 1176 put_tty_queue('\0', ldata); 1177 } 1178 put_tty_queue('\0', ldata); 1179 if (waitqueue_active(&tty->read_wait)) 1180 wake_up_interruptible_poll(&tty->read_wait, POLLIN); 1181} 1182 1183/** 1184 * n_tty_receive_overrun - handle overrun reporting 1185 * @tty: terminal 1186 * 1187 * Data arrived faster than we could process it. While the tty 1188 * driver has flagged this the bits that were missed are gone 1189 * forever. 1190 * 1191 * Called from the receive_buf path so single threaded. Does not 1192 * need locking as num_overrun and overrun_time are function 1193 * private. 1194 */ 1195 1196static void n_tty_receive_overrun(struct tty_struct *tty) 1197{ 1198 struct n_tty_data *ldata = tty->disc_data; 1199 char buf[64]; 1200 1201 ldata->num_overrun++; 1202 if (time_after(jiffies, ldata->overrun_time + HZ) || 1203 time_after(ldata->overrun_time, jiffies)) { 1204 printk(KERN_WARNING "%s: %d input overrun(s)\n", 1205 tty_name(tty, buf), 1206 ldata->num_overrun); 1207 ldata->overrun_time = jiffies; 1208 ldata->num_overrun = 0; 1209 } 1210} 1211 1212/** 1213 * n_tty_receive_parity_error - error notifier 1214 * @tty: terminal device 1215 * @c: character 1216 * 1217 * Process a parity error and queue the right data to indicate 1218 * the error case if necessary. 1219 * 1220 * n_tty_receive_buf()/producer path: 1221 * caller holds non-exclusive termios_rwsem 1222 */ 1223static void n_tty_receive_parity_error(struct tty_struct *tty, unsigned char c) 1224{ 1225 struct n_tty_data *ldata = tty->disc_data; 1226 1227 if (I_INPCK(tty)) { 1228 if (I_IGNPAR(tty)) 1229 return; 1230 if (I_PARMRK(tty)) { 1231 put_tty_queue('\377', ldata); 1232 put_tty_queue('\0', ldata); 1233 put_tty_queue(c, ldata); 1234 } else 1235 put_tty_queue('\0', ldata); 1236 } else 1237 put_tty_queue(c, ldata); 1238 if (waitqueue_active(&tty->read_wait)) 1239 wake_up_interruptible_poll(&tty->read_wait, POLLIN); 1240} 1241 1242static void 1243n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c) 1244{ 1245 isig(signal, tty); 1246 if (I_IXON(tty)) 1247 start_tty(tty); 1248 if (L_ECHO(tty)) { 1249 echo_char(c, tty); 1250 commit_echoes(tty); 1251 } else 1252 process_echoes(tty); 1253 return; 1254} 1255 1256/** 1257 * n_tty_receive_char - perform processing 1258 * @tty: terminal device 1259 * @c: character 1260 * 1261 * Process an individual character of input received from the driver. 1262 * This is serialized with respect to itself by the rules for the 1263 * driver above. 1264 * 1265 * n_tty_receive_buf()/producer path: 1266 * caller holds non-exclusive termios_rwsem 1267 * publishes canon_head if canonical mode is active 1268 * 1269 * Returns 1 if LNEXT was received, else returns 0 1270 */ 1271 1272static int 1273n_tty_receive_char_special(struct tty_struct *tty, unsigned char c) 1274{ 1275 struct n_tty_data *ldata = tty->disc_data; 1276 1277 if (I_IXON(tty)) { 1278 if (c == START_CHAR(tty)) { 1279 start_tty(tty); 1280 process_echoes(tty); 1281 return 0; 1282 } 1283 if (c == STOP_CHAR(tty)) { 1284 stop_tty(tty); 1285 return 0; 1286 } 1287 } 1288 1289 if (L_ISIG(tty)) { 1290 if (c == INTR_CHAR(tty)) { 1291 n_tty_receive_signal_char(tty, SIGINT, c); 1292 return 0; 1293 } else if (c == QUIT_CHAR(tty)) { 1294 n_tty_receive_signal_char(tty, SIGQUIT, c); 1295 return 0; 1296 } else if (c == SUSP_CHAR(tty)) { 1297 n_tty_receive_signal_char(tty, SIGTSTP, c); 1298 return 0; 1299 } 1300 } 1301 1302 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) { 1303 start_tty(tty); 1304 process_echoes(tty); 1305 } 1306 1307 if (c == '\r') { 1308 if (I_IGNCR(tty)) 1309 return 0; 1310 if (I_ICRNL(tty)) 1311 c = '\n'; 1312 } else if (c == '\n' && I_INLCR(tty)) 1313 c = '\r'; 1314 1315 if (ldata->icanon) { 1316 if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) || 1317 (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) { 1318 eraser(c, tty); 1319 commit_echoes(tty); 1320 return 0; 1321 } 1322 if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) { 1323 ldata->lnext = 1; 1324 if (L_ECHO(tty)) { 1325 finish_erasing(ldata); 1326 if (L_ECHOCTL(tty)) { 1327 echo_char_raw('^', ldata); 1328 echo_char_raw('\b', ldata); 1329 commit_echoes(tty); 1330 } 1331 } 1332 return 1; 1333 } 1334 if (c == REPRINT_CHAR(tty) && L_ECHO(tty) && L_IEXTEN(tty)) { 1335 size_t tail = ldata->canon_head; 1336 1337 finish_erasing(ldata); 1338 echo_char(c, tty); 1339 echo_char_raw('\n', ldata); 1340 while (tail != ldata->read_head) { 1341 echo_char(read_buf(ldata, tail), tty); 1342 tail++; 1343 } 1344 commit_echoes(tty); 1345 return 0; 1346 } 1347 if (c == '\n') { 1348 if (L_ECHO(tty) || L_ECHONL(tty)) { 1349 echo_char_raw('\n', ldata); 1350 commit_echoes(tty); 1351 } 1352 goto handle_newline; 1353 } 1354 if (c == EOF_CHAR(tty)) { 1355 c = __DISABLED_CHAR; 1356 goto handle_newline; 1357 } 1358 if ((c == EOL_CHAR(tty)) || 1359 (c == EOL2_CHAR(tty) && L_IEXTEN(tty))) { 1360 /* 1361 * XXX are EOL_CHAR and EOL2_CHAR echoed?!? 1362 */ 1363 if (L_ECHO(tty)) { 1364 /* Record the column of first canon char. */ 1365 if (ldata->canon_head == ldata->read_head) 1366 echo_set_canon_col(ldata); 1367 echo_char(c, tty); 1368 commit_echoes(tty); 1369 } 1370 /* 1371 * XXX does PARMRK doubling happen for 1372 * EOL_CHAR and EOL2_CHAR? 1373 */ 1374 if (c == (unsigned char) '\377' && I_PARMRK(tty)) 1375 put_tty_queue(c, ldata); 1376 1377handle_newline: 1378 set_bit(ldata->read_head & (N_TTY_BUF_SIZE - 1), ldata->read_flags); 1379 put_tty_queue(c, ldata); 1380 smp_store_release(&ldata->canon_head, ldata->read_head); 1381 kill_fasync(&tty->fasync, SIGIO, POLL_IN); 1382 wake_up_interruptible_poll(&tty->read_wait, POLLIN); 1383 return 0; 1384 } 1385 } 1386 1387 if (L_ECHO(tty)) { 1388 finish_erasing(ldata); 1389 if (c == '\n') 1390 echo_char_raw('\n', ldata); 1391 else { 1392 /* Record the column of first canon char. */ 1393 if (ldata->canon_head == ldata->read_head) 1394 echo_set_canon_col(ldata); 1395 echo_char(c, tty); 1396 } 1397 commit_echoes(tty); 1398 } 1399 1400 /* PARMRK doubling check */ 1401 if (c == (unsigned char) '\377' && I_PARMRK(tty)) 1402 put_tty_queue(c, ldata); 1403 1404 put_tty_queue(c, ldata); 1405 return 0; 1406} 1407 1408static inline void 1409n_tty_receive_char_inline(struct tty_struct *tty, unsigned char c) 1410{ 1411 struct n_tty_data *ldata = tty->disc_data; 1412 1413 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) { 1414 start_tty(tty); 1415 process_echoes(tty); 1416 } 1417 if (L_ECHO(tty)) { 1418 finish_erasing(ldata); 1419 /* Record the column of first canon char. */ 1420 if (ldata->canon_head == ldata->read_head) 1421 echo_set_canon_col(ldata); 1422 echo_char(c, tty); 1423 commit_echoes(tty); 1424 } 1425 /* PARMRK doubling check */ 1426 if (c == (unsigned char) '\377' && I_PARMRK(tty)) 1427 put_tty_queue(c, ldata); 1428 put_tty_queue(c, ldata); 1429} 1430 1431static void n_tty_receive_char(struct tty_struct *tty, unsigned char c) 1432{ 1433 n_tty_receive_char_inline(tty, c); 1434} 1435 1436static inline void 1437n_tty_receive_char_fast(struct tty_struct *tty, unsigned char c) 1438{ 1439 struct n_tty_data *ldata = tty->disc_data; 1440 1441 if (tty->stopped && !tty->flow_stopped && I_IXON(tty) && I_IXANY(tty)) { 1442 start_tty(tty); 1443 process_echoes(tty); 1444 } 1445 if (L_ECHO(tty)) { 1446 finish_erasing(ldata); 1447 /* Record the column of first canon char. */ 1448 if (ldata->canon_head == ldata->read_head) 1449 echo_set_canon_col(ldata); 1450 echo_char(c, tty); 1451 commit_echoes(tty); 1452 } 1453 put_tty_queue(c, ldata); 1454} 1455 1456static void n_tty_receive_char_closing(struct tty_struct *tty, unsigned char c) 1457{ 1458 if (I_ISTRIP(tty)) 1459 c &= 0x7f; 1460 if (I_IUCLC(tty) && L_IEXTEN(tty)) 1461 c = tolower(c); 1462 1463 if (I_IXON(tty)) { 1464 if (c == STOP_CHAR(tty)) 1465 stop_tty(tty); 1466 else if (c == START_CHAR(tty) || 1467 (tty->stopped && !tty->flow_stopped && I_IXANY(tty) && 1468 c != INTR_CHAR(tty) && c != QUIT_CHAR(tty) && 1469 c != SUSP_CHAR(tty))) { 1470 start_tty(tty); 1471 process_echoes(tty); 1472 } 1473 } 1474} 1475 1476static void 1477n_tty_receive_char_flagged(struct tty_struct *tty, unsigned char c, char flag) 1478{ 1479 char buf[64]; 1480 1481 switch (flag) { 1482 case TTY_BREAK: 1483 n_tty_receive_break(tty); 1484 break; 1485 case TTY_PARITY: 1486 case TTY_FRAME: 1487 n_tty_receive_parity_error(tty, c); 1488 break; 1489 case TTY_OVERRUN: 1490 n_tty_receive_overrun(tty); 1491 break; 1492 default: 1493 printk(KERN_ERR "%s: unknown flag %d\n", 1494 tty_name(tty, buf), flag); 1495 break; 1496 } 1497} 1498 1499static void 1500n_tty_receive_char_lnext(struct tty_struct *tty, unsigned char c, char flag) 1501{ 1502 struct n_tty_data *ldata = tty->disc_data; 1503 1504 ldata->lnext = 0; 1505 if (likely(flag == TTY_NORMAL)) { 1506 if (I_ISTRIP(tty)) 1507 c &= 0x7f; 1508 if (I_IUCLC(tty) && L_IEXTEN(tty)) 1509 c = tolower(c); 1510 n_tty_receive_char(tty, c); 1511 } else 1512 n_tty_receive_char_flagged(tty, c, flag); 1513} 1514 1515static void 1516n_tty_receive_buf_real_raw(struct tty_struct *tty, const unsigned char *cp, 1517 char *fp, int count) 1518{ 1519 struct n_tty_data *ldata = tty->disc_data; 1520 size_t n, head; 1521 1522 head = ldata->read_head & (N_TTY_BUF_SIZE - 1); 1523 n = min_t(size_t, count, N_TTY_BUF_SIZE - head); 1524 memcpy(read_buf_addr(ldata, head), cp, n); 1525 ldata->read_head += n; 1526 cp += n; 1527 count -= n; 1528 1529 head = ldata->read_head & (N_TTY_BUF_SIZE - 1); 1530 n = min_t(size_t, count, N_TTY_BUF_SIZE - head); 1531 memcpy(read_buf_addr(ldata, head), cp, n); 1532 ldata->read_head += n; 1533} 1534 1535static void 1536n_tty_receive_buf_raw(struct tty_struct *tty, const unsigned char *cp, 1537 char *fp, int count) 1538{ 1539 struct n_tty_data *ldata = tty->disc_data; 1540 char flag = TTY_NORMAL; 1541 1542 while (count--) { 1543 if (fp) 1544 flag = *fp++; 1545 if (likely(flag == TTY_NORMAL)) 1546 put_tty_queue(*cp++, ldata); 1547 else 1548 n_tty_receive_char_flagged(tty, *cp++, flag); 1549 } 1550} 1551 1552static void 1553n_tty_receive_buf_closing(struct tty_struct *tty, const unsigned char *cp, 1554 char *fp, int count) 1555{ 1556 char flag = TTY_NORMAL; 1557 1558 while (count--) { 1559 if (fp) 1560 flag = *fp++; 1561 if (likely(flag == TTY_NORMAL)) 1562 n_tty_receive_char_closing(tty, *cp++); 1563 else 1564 n_tty_receive_char_flagged(tty, *cp++, flag); 1565 } 1566} 1567 1568static void 1569n_tty_receive_buf_standard(struct tty_struct *tty, const unsigned char *cp, 1570 char *fp, int count) 1571{ 1572 struct n_tty_data *ldata = tty->disc_data; 1573 char flag = TTY_NORMAL; 1574 1575 while (count--) { 1576 if (fp) 1577 flag = *fp++; 1578 if (likely(flag == TTY_NORMAL)) { 1579 unsigned char c = *cp++; 1580 1581 if (I_ISTRIP(tty)) 1582 c &= 0x7f; 1583 if (I_IUCLC(tty) && L_IEXTEN(tty)) 1584 c = tolower(c); 1585 if (L_EXTPROC(tty)) { 1586 put_tty_queue(c, ldata); 1587 continue; 1588 } 1589 if (!test_bit(c, ldata->char_map)) 1590 n_tty_receive_char_inline(tty, c); 1591 else if (n_tty_receive_char_special(tty, c) && count) { 1592 if (fp) 1593 flag = *fp++; 1594 n_tty_receive_char_lnext(tty, *cp++, flag); 1595 count--; 1596 } 1597 } else 1598 n_tty_receive_char_flagged(tty, *cp++, flag); 1599 } 1600} 1601 1602static void 1603n_tty_receive_buf_fast(struct tty_struct *tty, const unsigned char *cp, 1604 char *fp, int count) 1605{ 1606 struct n_tty_data *ldata = tty->disc_data; 1607 char flag = TTY_NORMAL; 1608 1609 while (count--) { 1610 if (fp) 1611 flag = *fp++; 1612 if (likely(flag == TTY_NORMAL)) { 1613 unsigned char c = *cp++; 1614 1615 if (!test_bit(c, ldata->char_map)) 1616 n_tty_receive_char_fast(tty, c); 1617 else if (n_tty_receive_char_special(tty, c) && count) { 1618 if (fp) 1619 flag = *fp++; 1620 n_tty_receive_char_lnext(tty, *cp++, flag); 1621 count--; 1622 } 1623 } else 1624 n_tty_receive_char_flagged(tty, *cp++, flag); 1625 } 1626} 1627 1628static void __receive_buf(struct tty_struct *tty, const unsigned char *cp, 1629 char *fp, int count) 1630{ 1631 struct n_tty_data *ldata = tty->disc_data; 1632 bool preops = I_ISTRIP(tty) || (I_IUCLC(tty) && L_IEXTEN(tty)); 1633 1634 if (ldata->real_raw) 1635 n_tty_receive_buf_real_raw(tty, cp, fp, count); 1636 else if (ldata->raw || (L_EXTPROC(tty) && !preops)) 1637 n_tty_receive_buf_raw(tty, cp, fp, count); 1638 else if (tty->closing && !L_EXTPROC(tty)) 1639 n_tty_receive_buf_closing(tty, cp, fp, count); 1640 else { 1641 if (ldata->lnext) { 1642 char flag = TTY_NORMAL; 1643 1644 if (fp) 1645 flag = *fp++; 1646 n_tty_receive_char_lnext(tty, *cp++, flag); 1647 count--; 1648 } 1649 1650 if (!preops && !I_PARMRK(tty)) 1651 n_tty_receive_buf_fast(tty, cp, fp, count); 1652 else 1653 n_tty_receive_buf_standard(tty, cp, fp, count); 1654 1655 flush_echoes(tty); 1656 if (tty->ops->flush_chars) 1657 tty->ops->flush_chars(tty); 1658 } 1659 1660 if (ldata->icanon && !L_EXTPROC(tty)) 1661 return; 1662 1663 /* publish read_head to consumer */ 1664 smp_store_release(&ldata->commit_head, ldata->read_head); 1665 1666 if ((read_cnt(ldata) >= ldata->minimum_to_wake) || L_EXTPROC(tty)) { 1667 kill_fasync(&tty->fasync, SIGIO, POLL_IN); 1668 wake_up_interruptible_poll(&tty->read_wait, POLLIN); 1669 } 1670} 1671 1672/** 1673 * n_tty_receive_buf_common - process input 1674 * @tty: device to receive input 1675 * @cp: input chars 1676 * @fp: flags for each char (if NULL, all chars are TTY_NORMAL) 1677 * @count: number of input chars in @cp 1678 * 1679 * Called by the terminal driver when a block of characters has 1680 * been received. This function must be called from soft contexts 1681 * not from interrupt context. The driver is responsible for making 1682 * calls one at a time and in order (or using flush_to_ldisc) 1683 * 1684 * Returns the # of input chars from @cp which were processed. 1685 * 1686 * In canonical mode, the maximum line length is 4096 chars (including 1687 * the line termination char); lines longer than 4096 chars are 1688 * truncated. After 4095 chars, input data is still processed but 1689 * not stored. Overflow processing ensures the tty can always 1690 * receive more input until at least one line can be read. 1691 * 1692 * In non-canonical mode, the read buffer will only accept 4095 chars; 1693 * this provides the necessary space for a newline char if the input 1694 * mode is switched to canonical. 1695 * 1696 * Note it is possible for the read buffer to _contain_ 4096 chars 1697 * in non-canonical mode: the read buffer could already contain the 1698 * maximum canon line of 4096 chars when the mode is switched to 1699 * non-canonical. 1700 * 1701 * n_tty_receive_buf()/producer path: 1702 * claims non-exclusive termios_rwsem 1703 * publishes commit_head or canon_head 1704 */ 1705static int 1706n_tty_receive_buf_common(struct tty_struct *tty, const unsigned char *cp, 1707 char *fp, int count, int flow) 1708{ 1709 struct n_tty_data *ldata = tty->disc_data; 1710 int room, n, rcvd = 0, overflow; 1711 1712 down_read(&tty->termios_rwsem); 1713 1714 while (1) { 1715 /* 1716 * When PARMRK is set, each input char may take up to 3 chars 1717 * in the read buf; reduce the buffer space avail by 3x 1718 * 1719 * If we are doing input canonicalization, and there are no 1720 * pending newlines, let characters through without limit, so 1721 * that erase characters will be handled. Other excess 1722 * characters will be beeped. 1723 * 1724 * paired with store in *_copy_from_read_buf() -- guarantees 1725 * the consumer has loaded the data in read_buf up to the new 1726 * read_tail (so this producer will not overwrite unread data) 1727 */ 1728 size_t tail = smp_load_acquire(&ldata->read_tail); 1729 1730 room = N_TTY_BUF_SIZE - (ldata->read_head - tail); 1731 if (I_PARMRK(tty)) 1732 room = (room + 2) / 3; 1733 room--; 1734 if (room <= 0) { 1735 overflow = ldata->icanon && ldata->canon_head == tail; 1736 if (overflow && room < 0) 1737 ldata->read_head--; 1738 room = overflow; 1739 ldata->no_room = flow && !room; 1740 } else 1741 overflow = 0; 1742 1743 n = min(count, room); 1744 if (!n) 1745 break; 1746 1747 /* ignore parity errors if handling overflow */ 1748 if (!overflow || !fp || *fp != TTY_PARITY) 1749 __receive_buf(tty, cp, fp, n); 1750 1751 cp += n; 1752 if (fp) 1753 fp += n; 1754 count -= n; 1755 rcvd += n; 1756 } 1757 1758 tty->receive_room = room; 1759 1760 /* Unthrottle if handling overflow on pty */ 1761 if (tty->driver->type == TTY_DRIVER_TYPE_PTY) { 1762 if (overflow) { 1763 tty_set_flow_change(tty, TTY_UNTHROTTLE_SAFE); 1764 tty_unthrottle_safe(tty); 1765 __tty_set_flow_change(tty, 0); 1766 } 1767 } else 1768 n_tty_check_throttle(tty); 1769 1770 up_read(&tty->termios_rwsem); 1771 1772 return rcvd; 1773} 1774 1775static void n_tty_receive_buf(struct tty_struct *tty, const unsigned char *cp, 1776 char *fp, int count) 1777{ 1778 n_tty_receive_buf_common(tty, cp, fp, count, 0); 1779} 1780 1781static int n_tty_receive_buf2(struct tty_struct *tty, const unsigned char *cp, 1782 char *fp, int count) 1783{ 1784 return n_tty_receive_buf_common(tty, cp, fp, count, 1); 1785} 1786 1787int is_ignored(int sig) 1788{ 1789 return (sigismember(¤t->blocked, sig) || 1790 current->sighand->action[sig-1].sa.sa_handler == SIG_IGN); 1791} 1792 1793/** 1794 * n_tty_set_termios - termios data changed 1795 * @tty: terminal 1796 * @old: previous data 1797 * 1798 * Called by the tty layer when the user changes termios flags so 1799 * that the line discipline can plan ahead. This function cannot sleep 1800 * and is protected from re-entry by the tty layer. The user is 1801 * guaranteed that this function will not be re-entered or in progress 1802 * when the ldisc is closed. 1803 * 1804 * Locking: Caller holds tty->termios_rwsem 1805 */ 1806 1807static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old) 1808{ 1809 struct n_tty_data *ldata = tty->disc_data; 1810 1811 if (!old || (old->c_lflag ^ tty->termios.c_lflag) & ICANON) { 1812 bitmap_zero(ldata->read_flags, N_TTY_BUF_SIZE); 1813 ldata->line_start = ldata->read_tail; 1814 if (!L_ICANON(tty) || !read_cnt(ldata)) { 1815 ldata->canon_head = ldata->read_tail; 1816 ldata->push = 0; 1817 } else { 1818 set_bit((ldata->read_head - 1) & (N_TTY_BUF_SIZE - 1), 1819 ldata->read_flags); 1820 ldata->canon_head = ldata->read_head; 1821 ldata->push = 1; 1822 } 1823 ldata->commit_head = ldata->read_head; 1824 ldata->erasing = 0; 1825 ldata->lnext = 0; 1826 } 1827 1828 ldata->icanon = (L_ICANON(tty) != 0); 1829 1830 if (I_ISTRIP(tty) || I_IUCLC(tty) || I_IGNCR(tty) || 1831 I_ICRNL(tty) || I_INLCR(tty) || L_ICANON(tty) || 1832 I_IXON(tty) || L_ISIG(tty) || L_ECHO(tty) || 1833 I_PARMRK(tty)) { 1834 bitmap_zero(ldata->char_map, 256); 1835 1836 if (I_IGNCR(tty) || I_ICRNL(tty)) 1837 set_bit('\r', ldata->char_map); 1838 if (I_INLCR(tty)) 1839 set_bit('\n', ldata->char_map); 1840 1841 if (L_ICANON(tty)) { 1842 set_bit(ERASE_CHAR(tty), ldata->char_map); 1843 set_bit(KILL_CHAR(tty), ldata->char_map); 1844 set_bit(EOF_CHAR(tty), ldata->char_map); 1845 set_bit('\n', ldata->char_map); 1846 set_bit(EOL_CHAR(tty), ldata->char_map); 1847 if (L_IEXTEN(tty)) { 1848 set_bit(WERASE_CHAR(tty), ldata->char_map); 1849 set_bit(LNEXT_CHAR(tty), ldata->char_map); 1850 set_bit(EOL2_CHAR(tty), ldata->char_map); 1851 if (L_ECHO(tty)) 1852 set_bit(REPRINT_CHAR(tty), 1853 ldata->char_map); 1854 } 1855 } 1856 if (I_IXON(tty)) { 1857 set_bit(START_CHAR(tty), ldata->char_map); 1858 set_bit(STOP_CHAR(tty), ldata->char_map); 1859 } 1860 if (L_ISIG(tty)) { 1861 set_bit(INTR_CHAR(tty), ldata->char_map); 1862 set_bit(QUIT_CHAR(tty), ldata->char_map); 1863 set_bit(SUSP_CHAR(tty), ldata->char_map); 1864 } 1865 clear_bit(__DISABLED_CHAR, ldata->char_map); 1866 ldata->raw = 0; 1867 ldata->real_raw = 0; 1868 } else { 1869 ldata->raw = 1; 1870 if ((I_IGNBRK(tty) || (!I_BRKINT(tty) && !I_PARMRK(tty))) && 1871 (I_IGNPAR(tty) || !I_INPCK(tty)) && 1872 (tty->driver->flags & TTY_DRIVER_REAL_RAW)) 1873 ldata->real_raw = 1; 1874 else 1875 ldata->real_raw = 0; 1876 } 1877 /* 1878 * Fix tty hang when I_IXON(tty) is cleared, but the tty 1879 * been stopped by STOP_CHAR(tty) before it. 1880 */ 1881 if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) { 1882 start_tty(tty); 1883 process_echoes(tty); 1884 } 1885 1886 /* The termios change make the tty ready for I/O */ 1887 wake_up_interruptible(&tty->write_wait); 1888 wake_up_interruptible(&tty->read_wait); 1889} 1890 1891/** 1892 * n_tty_close - close the ldisc for this tty 1893 * @tty: device 1894 * 1895 * Called from the terminal layer when this line discipline is 1896 * being shut down, either because of a close or becsuse of a 1897 * discipline change. The function will not be called while other 1898 * ldisc methods are in progress. 1899 */ 1900 1901static void n_tty_close(struct tty_struct *tty) 1902{ 1903 struct n_tty_data *ldata = tty->disc_data; 1904 1905 if (tty->link) 1906 n_tty_packet_mode_flush(tty); 1907 1908 vfree(ldata); 1909 tty->disc_data = NULL; 1910} 1911 1912/** 1913 * n_tty_open - open an ldisc 1914 * @tty: terminal to open 1915 * 1916 * Called when this line discipline is being attached to the 1917 * terminal device. Can sleep. Called serialized so that no 1918 * other events will occur in parallel. No further open will occur 1919 * until a close. 1920 */ 1921 1922static int n_tty_open(struct tty_struct *tty) 1923{ 1924 struct n_tty_data *ldata; 1925 1926 /* Currently a malloc failure here can panic */ 1927 ldata = vmalloc(sizeof(*ldata)); 1928 if (!ldata) 1929 goto err; 1930 1931 ldata->overrun_time = jiffies; 1932 mutex_init(&ldata->atomic_read_lock); 1933 mutex_init(&ldata->output_lock); 1934 1935 tty->disc_data = ldata; 1936 reset_buffer_flags(tty->disc_data); 1937 ldata->column = 0; 1938 ldata->canon_column = 0; 1939 ldata->minimum_to_wake = 1; 1940 ldata->num_overrun = 0; 1941 ldata->no_room = 0; 1942 ldata->lnext = 0; 1943 tty->closing = 0; 1944 /* indicate buffer work may resume */ 1945 clear_bit(TTY_LDISC_HALTED, &tty->flags); 1946 n_tty_set_termios(tty, NULL); 1947 tty_unthrottle(tty); 1948 1949 return 0; 1950err: 1951 return -ENOMEM; 1952} 1953 1954static inline int input_available_p(struct tty_struct *tty, int poll) 1955{ 1956 struct n_tty_data *ldata = tty->disc_data; 1957 int amt = poll && !TIME_CHAR(tty) && MIN_CHAR(tty) ? MIN_CHAR(tty) : 1; 1958 1959 if (ldata->icanon && !L_EXTPROC(tty)) 1960 return ldata->canon_head != ldata->read_tail; 1961 else 1962 return ldata->commit_head - ldata->read_tail >= amt; 1963} 1964 1965/** 1966 * copy_from_read_buf - copy read data directly 1967 * @tty: terminal device 1968 * @b: user data 1969 * @nr: size of data 1970 * 1971 * Helper function to speed up n_tty_read. It is only called when 1972 * ICANON is off; it copies characters straight from the tty queue to 1973 * user space directly. It can be profitably called twice; once to 1974 * drain the space from the tail pointer to the (physical) end of the 1975 * buffer, and once to drain the space from the (physical) beginning of 1976 * the buffer to head pointer. 1977 * 1978 * Called under the ldata->atomic_read_lock sem 1979 * 1980 * n_tty_read()/consumer path: 1981 * caller holds non-exclusive termios_rwsem 1982 * read_tail published 1983 */ 1984 1985static int copy_from_read_buf(struct tty_struct *tty, 1986 unsigned char __user **b, 1987 size_t *nr) 1988 1989{ 1990 struct n_tty_data *ldata = tty->disc_data; 1991 int retval; 1992 size_t n; 1993 bool is_eof; 1994 size_t head = smp_load_acquire(&ldata->commit_head); 1995 size_t tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1); 1996 1997 retval = 0; 1998 n = min(head - ldata->read_tail, N_TTY_BUF_SIZE - tail); 1999 n = min(*nr, n); 2000 if (n) { 2001 retval = copy_to_user(*b, read_buf_addr(ldata, tail), n); 2002 n -= retval; 2003 is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty); 2004 tty_audit_add_data(tty, read_buf_addr(ldata, tail), n, 2005 ldata->icanon); 2006 smp_store_release(&ldata->read_tail, ldata->read_tail + n); 2007 /* Turn single EOF into zero-length read */ 2008 if (L_EXTPROC(tty) && ldata->icanon && is_eof && 2009 (head == ldata->read_tail)) 2010 n = 0; 2011 *b += n; 2012 *nr -= n; 2013 } 2014 return retval; 2015} 2016 2017/** 2018 * canon_copy_from_read_buf - copy read data in canonical mode 2019 * @tty: terminal device 2020 * @b: user data 2021 * @nr: size of data 2022 * 2023 * Helper function for n_tty_read. It is only called when ICANON is on; 2024 * it copies one line of input up to and including the line-delimiting 2025 * character into the user-space buffer. 2026 * 2027 * NB: When termios is changed from non-canonical to canonical mode and 2028 * the read buffer contains data, n_tty_set_termios() simulates an EOF 2029 * push (as if C-d were input) _without_ the DISABLED_CHAR in the buffer. 2030 * This causes data already processed as input to be immediately available 2031 * as input although a newline has not been received. 2032 * 2033 * Called under the atomic_read_lock mutex 2034 * 2035 * n_tty_read()/consumer path: 2036 * caller holds non-exclusive termios_rwsem 2037 * read_tail published 2038 */ 2039 2040static int canon_copy_from_read_buf(struct tty_struct *tty, 2041 unsigned char __user **b, 2042 size_t *nr) 2043{ 2044 struct n_tty_data *ldata = tty->disc_data; 2045 size_t n, size, more, c; 2046 size_t eol; 2047 size_t tail; 2048 int ret, found = 0; 2049 bool eof_push = 0; 2050 2051 /* N.B. avoid overrun if nr == 0 */ 2052 n = min(*nr, smp_load_acquire(&ldata->canon_head) - ldata->read_tail); 2053 if (!n) 2054 return 0; 2055 2056 tail = ldata->read_tail & (N_TTY_BUF_SIZE - 1); 2057 size = min_t(size_t, tail + n, N_TTY_BUF_SIZE); 2058 2059 n_tty_trace("%s: nr:%zu tail:%zu n:%zu size:%zu\n", 2060 __func__, *nr, tail, n, size); 2061 2062 eol = find_next_bit(ldata->read_flags, size, tail); 2063 more = n - (size - tail); 2064 if (eol == N_TTY_BUF_SIZE && more) { 2065 /* scan wrapped without finding set bit */ 2066 eol = find_next_bit(ldata->read_flags, more, 0); 2067 if (eol != more) 2068 found = 1; 2069 } else if (eol != size) 2070 found = 1; 2071 2072 size = N_TTY_BUF_SIZE - tail; 2073 n = eol - tail; 2074 if (n > N_TTY_BUF_SIZE) 2075 n += N_TTY_BUF_SIZE; 2076 n += found; 2077 c = n; 2078 2079 if (found && !ldata->push && read_buf(ldata, eol) == __DISABLED_CHAR) { 2080 n--; 2081 eof_push = !n && ldata->read_tail != ldata->line_start; 2082 } 2083 2084 n_tty_trace("%s: eol:%zu found:%d n:%zu c:%zu size:%zu more:%zu\n", 2085 __func__, eol, found, n, c, size, more); 2086 2087 if (n > size) { 2088 ret = tty_copy_to_user(tty, *b, read_buf_addr(ldata, tail), size); 2089 if (ret) 2090 return -EFAULT; 2091 ret = tty_copy_to_user(tty, *b + size, ldata->read_buf, n - size); 2092 } else 2093 ret = tty_copy_to_user(tty, *b, read_buf_addr(ldata, tail), n); 2094 2095 if (ret) 2096 return -EFAULT; 2097 *b += n; 2098 *nr -= n; 2099 2100 if (found) 2101 clear_bit(eol, ldata->read_flags); 2102 smp_store_release(&ldata->read_tail, ldata->read_tail + c); 2103 2104 if (found) { 2105 if (!ldata->push) 2106 ldata->line_start = ldata->read_tail; 2107 else 2108 ldata->push = 0; 2109 tty_audit_push(tty); 2110 } 2111 return eof_push ? -EAGAIN : 0; 2112} 2113 2114extern ssize_t redirected_tty_write(struct file *, const char __user *, 2115 size_t, loff_t *); 2116 2117/** 2118 * job_control - check job control 2119 * @tty: tty 2120 * @file: file handle 2121 * 2122 * Perform job control management checks on this file/tty descriptor 2123 * and if appropriate send any needed signals and return a negative 2124 * error code if action should be taken. 2125 * 2126 * Locking: redirected write test is safe 2127 * current->signal->tty check is safe 2128 * ctrl_lock to safely reference tty->pgrp 2129 */ 2130 2131static int job_control(struct tty_struct *tty, struct file *file) 2132{ 2133 /* Job control check -- must be done at start and after 2134 every sleep (POSIX.1 7.1.1.4). */ 2135 /* NOTE: not yet done after every sleep pending a thorough 2136 check of the logic of this change. -- jlc */ 2137 /* don't stop on /dev/console */ 2138 if (file->f_op->write == redirected_tty_write || 2139 current->signal->tty != tty) 2140 return 0; 2141 2142 spin_lock_irq(&tty->ctrl_lock); 2143 if (!tty->pgrp) 2144 printk(KERN_ERR "n_tty_read: no tty->pgrp!\n"); 2145 else if (task_pgrp(current) != tty->pgrp) { 2146 spin_unlock_irq(&tty->ctrl_lock); 2147 if (is_ignored(SIGTTIN) || is_current_pgrp_orphaned()) 2148 return -EIO; 2149 kill_pgrp(task_pgrp(current), SIGTTIN, 1); 2150 set_thread_flag(TIF_SIGPENDING); 2151 return -ERESTARTSYS; 2152 } 2153 spin_unlock_irq(&tty->ctrl_lock); 2154 return 0; 2155} 2156 2157 2158/** 2159 * n_tty_read - read function for tty 2160 * @tty: tty device 2161 * @file: file object 2162 * @buf: userspace buffer pointer 2163 * @nr: size of I/O 2164 * 2165 * Perform reads for the line discipline. We are guaranteed that the 2166 * line discipline will not be closed under us but we may get multiple 2167 * parallel readers and must handle this ourselves. We may also get 2168 * a hangup. Always called in user context, may sleep. 2169 * 2170 * This code must be sure never to sleep through a hangup. 2171 * 2172 * n_tty_read()/consumer path: 2173 * claims non-exclusive termios_rwsem 2174 * publishes read_tail 2175 */ 2176 2177static ssize_t n_tty_read(struct tty_struct *tty, struct file *file, 2178 unsigned char __user *buf, size_t nr) 2179{ 2180 struct n_tty_data *ldata = tty->disc_data; 2181 unsigned char __user *b = buf; 2182 DEFINE_WAIT_FUNC(wait, woken_wake_function); 2183 int c; 2184 int minimum, time; 2185 ssize_t retval = 0; 2186 long timeout; 2187 int packet; 2188 size_t tail; 2189 2190 c = job_control(tty, file); 2191 if (c < 0) 2192 return c; 2193 2194 /* 2195 * Internal serialization of reads. 2196 */ 2197 if (file->f_flags & O_NONBLOCK) { 2198 if (!mutex_trylock(&ldata->atomic_read_lock)) 2199 return -EAGAIN; 2200 } else { 2201 if (mutex_lock_interruptible(&ldata->atomic_read_lock)) 2202 return -ERESTARTSYS; 2203 } 2204 2205 down_read(&tty->termios_rwsem); 2206 2207 minimum = time = 0; 2208 timeout = MAX_SCHEDULE_TIMEOUT; 2209 if (!ldata->icanon) { 2210 minimum = MIN_CHAR(tty); 2211 if (minimum) { 2212 time = (HZ / 10) * TIME_CHAR(tty); 2213 if (time) 2214 ldata->minimum_to_wake = 1; 2215 else if (!waitqueue_active(&tty->read_wait) || 2216 (ldata->minimum_to_wake > minimum)) 2217 ldata->minimum_to_wake = minimum; 2218 } else { 2219 timeout = (HZ / 10) * TIME_CHAR(tty); 2220 ldata->minimum_to_wake = minimum = 1; 2221 } 2222 } 2223 2224 packet = tty->packet; 2225 tail = ldata->read_tail; 2226 2227 add_wait_queue(&tty->read_wait, &wait); 2228 while (nr) { 2229 /* First test for status change. */ 2230 if (packet && tty->link->ctrl_status) { 2231 unsigned char cs; 2232 if (b != buf) 2233 break; 2234 spin_lock_irq(&tty->link->ctrl_lock); 2235 cs = tty->link->ctrl_status; 2236 tty->link->ctrl_status = 0; 2237 spin_unlock_irq(&tty->link->ctrl_lock); 2238 if (tty_put_user(tty, cs, b++)) { 2239 retval = -EFAULT; 2240 b--; 2241 break; 2242 } 2243 nr--; 2244 break; 2245 } 2246 2247 if (((minimum - (b - buf)) < ldata->minimum_to_wake) && 2248 ((minimum - (b - buf)) >= 1)) 2249 ldata->minimum_to_wake = (minimum - (b - buf)); 2250 2251 if (!input_available_p(tty, 0)) { 2252 up_read(&tty->termios_rwsem); 2253 tty_buffer_flush_work(tty->port); 2254 down_read(&tty->termios_rwsem); 2255 if (!input_available_p(tty, 0)) { 2256 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) { 2257 retval = -EIO; 2258 break; 2259 } 2260 if (tty_hung_up_p(file)) 2261 break; 2262 if (!timeout) 2263 break; 2264 if (file->f_flags & O_NONBLOCK) { 2265 retval = -EAGAIN; 2266 break; 2267 } 2268 if (signal_pending(current)) { 2269 retval = -ERESTARTSYS; 2270 break; 2271 } 2272 up_read(&tty->termios_rwsem); 2273 2274 timeout = wait_woken(&wait, TASK_INTERRUPTIBLE, 2275 timeout); 2276 2277 down_read(&tty->termios_rwsem); 2278 continue; 2279 } 2280 } 2281 2282 if (ldata->icanon && !L_EXTPROC(tty)) { 2283 retval = canon_copy_from_read_buf(tty, &b, &nr); 2284 if (retval == -EAGAIN) { 2285 retval = 0; 2286 continue; 2287 } else if (retval) 2288 break; 2289 } else { 2290 int uncopied; 2291 2292 /* Deal with packet mode. */ 2293 if (packet && b == buf) { 2294 if (tty_put_user(tty, TIOCPKT_DATA, b++)) { 2295 retval = -EFAULT; 2296 b--; 2297 break; 2298 } 2299 nr--; 2300 } 2301 2302 uncopied = copy_from_read_buf(tty, &b, &nr); 2303 uncopied += copy_from_read_buf(tty, &b, &nr); 2304 if (uncopied) { 2305 retval = -EFAULT; 2306 break; 2307 } 2308 } 2309 2310 n_tty_check_unthrottle(tty); 2311 2312 if (b - buf >= minimum) 2313 break; 2314 if (time) 2315 timeout = time; 2316 } 2317 if (tail != ldata->read_tail) 2318 n_tty_kick_worker(tty); 2319 up_read(&tty->termios_rwsem); 2320 2321 remove_wait_queue(&tty->read_wait, &wait); 2322 if (!waitqueue_active(&tty->read_wait)) 2323 ldata->minimum_to_wake = minimum; 2324 2325 mutex_unlock(&ldata->atomic_read_lock); 2326 2327 if (b - buf) 2328 retval = b - buf; 2329 2330 return retval; 2331} 2332 2333/** 2334 * n_tty_write - write function for tty 2335 * @tty: tty device 2336 * @file: file object 2337 * @buf: userspace buffer pointer 2338 * @nr: size of I/O 2339 * 2340 * Write function of the terminal device. This is serialized with 2341 * respect to other write callers but not to termios changes, reads 2342 * and other such events. Since the receive code will echo characters, 2343 * thus calling driver write methods, the output_lock is used in 2344 * the output processing functions called here as well as in the 2345 * echo processing function to protect the column state and space 2346 * left in the buffer. 2347 * 2348 * This code must be sure never to sleep through a hangup. 2349 * 2350 * Locking: output_lock to protect column state and space left 2351 * (note that the process_output*() functions take this 2352 * lock themselves) 2353 */ 2354 2355static ssize_t n_tty_write(struct tty_struct *tty, struct file *file, 2356 const unsigned char *buf, size_t nr) 2357{ 2358 const unsigned char *b = buf; 2359 DEFINE_WAIT_FUNC(wait, woken_wake_function); 2360 int c; 2361 ssize_t retval = 0; 2362 2363 /* Job control check -- must be done at start (POSIX.1 7.1.1.4). */ 2364 if (L_TOSTOP(tty) && file->f_op->write != redirected_tty_write) { 2365 retval = tty_check_change(tty); 2366 if (retval) 2367 return retval; 2368 } 2369 2370 down_read(&tty->termios_rwsem); 2371 2372 /* Write out any echoed characters that are still pending */ 2373 process_echoes(tty); 2374 2375 add_wait_queue(&tty->write_wait, &wait); 2376 while (1) { 2377 if (signal_pending(current)) { 2378 retval = -ERESTARTSYS; 2379 break; 2380 } 2381 if (tty_hung_up_p(file) || (tty->link && !tty->link->count)) { 2382 retval = -EIO; 2383 break; 2384 } 2385 if (O_OPOST(tty)) { 2386 while (nr > 0) { 2387 ssize_t num = process_output_block(tty, b, nr); 2388 if (num < 0) { 2389 if (num == -EAGAIN) 2390 break; 2391 retval = num; 2392 goto break_out; 2393 } 2394 b += num; 2395 nr -= num; 2396 if (nr == 0) 2397 break; 2398 c = *b; 2399 if (process_output(c, tty) < 0) 2400 break; 2401 b++; nr--; 2402 } 2403 if (tty->ops->flush_chars) 2404 tty->ops->flush_chars(tty); 2405 } else { 2406 struct n_tty_data *ldata = tty->disc_data; 2407 2408 while (nr > 0) { 2409 mutex_lock(&ldata->output_lock); 2410 c = tty->ops->write(tty, b, nr); 2411 mutex_unlock(&ldata->output_lock); 2412 if (c < 0) { 2413 retval = c; 2414 goto break_out; 2415 } 2416 if (!c) 2417 break; 2418 b += c; 2419 nr -= c; 2420 } 2421 } 2422 if (!nr) 2423 break; 2424 if (file->f_flags & O_NONBLOCK) { 2425 retval = -EAGAIN; 2426 break; 2427 } 2428 up_read(&tty->termios_rwsem); 2429 2430 wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT); 2431 2432 down_read(&tty->termios_rwsem); 2433 } 2434break_out: 2435 remove_wait_queue(&tty->write_wait, &wait); 2436 if (b - buf != nr && tty->fasync) 2437 set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 2438 up_read(&tty->termios_rwsem); 2439 return (b - buf) ? b - buf : retval; 2440} 2441 2442/** 2443 * n_tty_poll - poll method for N_TTY 2444 * @tty: terminal device 2445 * @file: file accessing it 2446 * @wait: poll table 2447 * 2448 * Called when the line discipline is asked to poll() for data or 2449 * for special events. This code is not serialized with respect to 2450 * other events save open/close. 2451 * 2452 * This code must be sure never to sleep through a hangup. 2453 * Called without the kernel lock held - fine 2454 */ 2455 2456static unsigned int n_tty_poll(struct tty_struct *tty, struct file *file, 2457 poll_table *wait) 2458{ 2459 struct n_tty_data *ldata = tty->disc_data; 2460 unsigned int mask = 0; 2461 2462 poll_wait(file, &tty->read_wait, wait); 2463 poll_wait(file, &tty->write_wait, wait); 2464 if (input_available_p(tty, 1)) 2465 mask |= POLLIN | POLLRDNORM; 2466 else { 2467 tty_buffer_flush_work(tty->port); 2468 if (input_available_p(tty, 1)) 2469 mask |= POLLIN | POLLRDNORM; 2470 } 2471 if (tty->packet && tty->link->ctrl_status) 2472 mask |= POLLPRI | POLLIN | POLLRDNORM; 2473 if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) 2474 mask |= POLLHUP; 2475 if (tty_hung_up_p(file)) 2476 mask |= POLLHUP; 2477 if (!(mask & (POLLHUP | POLLIN | POLLRDNORM))) { 2478 if (MIN_CHAR(tty) && !TIME_CHAR(tty)) 2479 ldata->minimum_to_wake = MIN_CHAR(tty); 2480 else 2481 ldata->minimum_to_wake = 1; 2482 } 2483 if (tty->ops->write && !tty_is_writelocked(tty) && 2484 tty_chars_in_buffer(tty) < WAKEUP_CHARS && 2485 tty_write_room(tty) > 0) 2486 mask |= POLLOUT | POLLWRNORM; 2487 return mask; 2488} 2489 2490static unsigned long inq_canon(struct n_tty_data *ldata) 2491{ 2492 size_t nr, head, tail; 2493 2494 if (ldata->canon_head == ldata->read_tail) 2495 return 0; 2496 head = ldata->canon_head; 2497 tail = ldata->read_tail; 2498 nr = head - tail; 2499 /* Skip EOF-chars.. */ 2500 while (head != tail) { 2501 if (test_bit(tail & (N_TTY_BUF_SIZE - 1), ldata->read_flags) && 2502 read_buf(ldata, tail) == __DISABLED_CHAR) 2503 nr--; 2504 tail++; 2505 } 2506 return nr; 2507} 2508 2509static int n_tty_ioctl(struct tty_struct *tty, struct file *file, 2510 unsigned int cmd, unsigned long arg) 2511{ 2512 struct n_tty_data *ldata = tty->disc_data; 2513 int retval; 2514 2515 switch (cmd) { 2516 case TIOCOUTQ: 2517 return put_user(tty_chars_in_buffer(tty), (int __user *) arg); 2518 case TIOCINQ: 2519 down_write(&tty->termios_rwsem); 2520 if (L_ICANON(tty)) 2521 retval = inq_canon(ldata); 2522 else 2523 retval = read_cnt(ldata); 2524 up_write(&tty->termios_rwsem); 2525 return put_user(retval, (unsigned int __user *) arg); 2526 default: 2527 return n_tty_ioctl_helper(tty, file, cmd, arg); 2528 } 2529} 2530 2531static void n_tty_fasync(struct tty_struct *tty, int on) 2532{ 2533 struct n_tty_data *ldata = tty->disc_data; 2534 2535 if (!waitqueue_active(&tty->read_wait)) { 2536 if (on) 2537 ldata->minimum_to_wake = 1; 2538 else if (!tty->fasync) 2539 ldata->minimum_to_wake = N_TTY_BUF_SIZE; 2540 } 2541} 2542 2543struct tty_ldisc_ops tty_ldisc_N_TTY = { 2544 .magic = TTY_LDISC_MAGIC, 2545 .name = "n_tty", 2546 .open = n_tty_open, 2547 .close = n_tty_close, 2548 .flush_buffer = n_tty_flush_buffer, 2549 .chars_in_buffer = n_tty_chars_in_buffer, 2550 .read = n_tty_read, 2551 .write = n_tty_write, 2552 .ioctl = n_tty_ioctl, 2553 .set_termios = n_tty_set_termios, 2554 .poll = n_tty_poll, 2555 .receive_buf = n_tty_receive_buf, 2556 .write_wakeup = n_tty_write_wakeup, 2557 .fasync = n_tty_fasync, 2558 .receive_buf2 = n_tty_receive_buf2, 2559}; 2560 2561/** 2562 * n_tty_inherit_ops - inherit N_TTY methods 2563 * @ops: struct tty_ldisc_ops where to save N_TTY methods 2564 * 2565 * Enables a 'subclass' line discipline to 'inherit' N_TTY 2566 * methods. 2567 */ 2568 2569void n_tty_inherit_ops(struct tty_ldisc_ops *ops) 2570{ 2571 *ops = tty_ldisc_N_TTY; 2572 ops->owner = NULL; 2573 ops->refcount = ops->flags = 0; 2574} 2575EXPORT_SYMBOL_GPL(n_tty_inherit_ops); 2576