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