sys/kern/tty_inq.c

   1 /*-
   2  * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
   3  * All rights reserved.
   4  *
   5  * Portions of this software were developed under sponsorship from Snow
   6  * B.V., the Netherlands.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #include <sys/cdefs.h>
  31 __FBSDID("$FreeBSD$");
  32
  33 #include <sys/param.h>
  34 #include <sys/kernel.h>
  35 #include <sys/lock.h>
  36 #include <sys/queue.h>
  37 #include <sys/sysctl.h>
  38 #include <sys/systm.h>
  39 #include <sys/tty.h>
  40 #include <sys/uio.h>
  41
  42 #include <vm/uma.h>
  43
  44 /*
  45  * TTY input queue buffering.
  46  *
  47  * Unlike the output queue, the input queue has more features that are
  48  * needed to properly implement various features offered by the TTY
  49  * interface:
  50  *
  51  * - Data can be removed from the tail of the queue, which is used to
  52  *   implement backspace.
  53  * - Once in a while, input has to be `canonicalized'. When ICANON is
  54  *   turned on, this will be done after a CR has been inserted.
  55  *   Otherwise, it should be done after any character has been inserted.
  56  * - The input queue can store one bit per byte, called the quoting bit.
  57  *   This bit is used by TTYDISC to make backspace work on quoted
  58  *   characters.
  59  *
  60  * In most cases, there is probably less input than output, so unlike
  61  * the outq, we'll stick to 128 byte blocks here.
  62  */
  63
  64 static int ttyinq_flush_secure = 1;
  65 SYSCTL_INT(_kern, OID_AUTO, tty_inq_flush_secure, CTLFLAG_RW,
  66         &ttyinq_flush_secure, 0, "Zero buffers while flushing");
  67
  68 #define TTYINQ_QUOTESIZE        (TTYINQ_DATASIZE / BMSIZE)
  69 #define BMSIZE                  32
  70 #define GETBIT(tib,boff) \
  71         ((tib)->tib_quotes[(boff) / BMSIZE] & (1 << ((boff) % BMSIZE)))
  72 #define SETBIT(tib,boff) \
  73         ((tib)->tib_quotes[(boff) / BMSIZE] |= (1 << ((boff) % BMSIZE)))
  74 #define CLRBIT(tib,boff) \
  75         ((tib)->tib_quotes[(boff) / BMSIZE] &= ~(1 << ((boff) % BMSIZE)))
  76
  77 struct ttyinq_block {
  78         struct ttyinq_block     *tib_prev;
  79         struct ttyinq_block     *tib_next;
  80         uint32_t                tib_quotes[TTYINQ_QUOTESIZE];
  81         char                    tib_data[TTYINQ_DATASIZE];
  82 };
  83
  84 static uma_zone_t ttyinq_zone;
  85
  86 #define TTYINQ_INSERT_TAIL(ti, tib) do {                                \
  87         if (ti->ti_end == 0) {                                          \
  88                 tib->tib_prev = NULL;                                   \
  89                 tib->tib_next = ti->ti_firstblock;                      \
  90                 ti->ti_firstblock = tib;                                \
  91         } else {                                                        \
  92                 tib->tib_prev = ti->ti_lastblock;                       \
  93                 tib->tib_next = ti->ti_lastblock->tib_next;             \
  94                 ti->ti_lastblock->tib_next = tib;                       \
  95         }                                                               \
  96         if (tib->tib_next != NULL)                                      \
  97                 tib->tib_next->tib_prev = tib;                          \
  98         ti->ti_nblocks++;                                               \
  99 } while (0)
 100
 101 #define TTYINQ_REMOVE_HEAD(ti) do {                                     \
 102         ti->ti_firstblock = ti->ti_firstblock->tib_next;                \
 103         if (ti->ti_firstblock != NULL)                                  \
 104                 ti->ti_firstblock->tib_prev = NULL;                     \
 105         ti->ti_nblocks--;                                               \
 106 } while (0)
 107
 108 #define TTYINQ_RECYCLE(ti, tib) do {                                    \
 109         if (ti->ti_quota <= ti->ti_nblocks)                             \
 110                 uma_zfree(ttyinq_zone, tib);                            \
 111         else                                                            \
 112                 TTYINQ_INSERT_TAIL(ti, tib);                            \
 113 } while (0)
 114
 115 int
 116 ttyinq_setsize(struct ttyinq *ti, struct tty *tp, size_t size)
 117 {
 118         struct ttyinq_block *tib;
 119
 120         ti->ti_quota = howmany(size, TTYINQ_DATASIZE);
 121
 122         while (ti->ti_quota > ti->ti_nblocks) {
 123                 /*
 124                  * List is getting bigger.
 125                  * Add new blocks to the tail of the list.
 126                  *
 127                  * We must unlock the TTY temporarily, because we need
 128                  * to allocate memory. This won't be a problem, because
 129                  * in the worst case, another thread ends up here, which
 130                  * may cause us to allocate too many blocks, but this
 131                  * will be caught by the loop below.
 132                  */
 133                 tty_unlock(tp);
 134                 tib = uma_zalloc(ttyinq_zone, M_WAITOK);
 135                 tty_lock(tp);
 136
 137                 if (tty_gone(tp)) {
 138                         uma_zfree(ttyinq_zone, tib);
 139                         return (ENXIO);
 140                 }
 141
 142                 TTYINQ_INSERT_TAIL(ti, tib);
 143         }
 144         return (0);
 145 }
 146
 147 void
 148 ttyinq_free(struct ttyinq *ti)
 149 {
 150         struct ttyinq_block *tib;
 151
 152         ttyinq_flush(ti);
 153         ti->ti_quota = 0;
 154
 155         while ((tib = ti->ti_firstblock) != NULL) {
 156                 TTYINQ_REMOVE_HEAD(ti);
 157                 uma_zfree(ttyinq_zone, tib);
 158         }
 159
 160         MPASS(ti->ti_nblocks == 0);
 161 }
 162
 163 int
 164 ttyinq_read_uio(struct ttyinq *ti, struct tty *tp, struct uio *uio,
 165     size_t rlen, size_t flen)
 166 {
 167
 168         MPASS(rlen <= uio->uio_resid);
 169
 170         while (rlen > 0) {
 171                 int error;
 172                 struct ttyinq_block *tib;
 173                 size_t cbegin, cend, clen;
 174
 175                 /* See if there still is data. */
 176                 if (ti->ti_begin == ti->ti_linestart)
 177                         return (0);
 178                 tib = ti->ti_firstblock;
 179                 if (tib == NULL)
 180                         return (0);
 181
 182                 /*
 183                  * The end address should be the lowest of these three:
 184                  * - The write pointer
 185                  * - The blocksize - we can't read beyond the block
 186                  * - The end address if we could perform the full read
 187                  */
 188                 cbegin = ti->ti_begin;
 189                 cend = MIN(MIN(ti->ti_linestart, ti->ti_begin + rlen),
 190                     TTYINQ_DATASIZE);
 191                 clen = cend - cbegin;
 192                 MPASS(clen >= flen);
 193                 rlen -= clen;
 194
 195                 /*
 196                  * We can prevent buffering in some cases:
 197                  * - We need to read the block until the end.
 198                  * - We don't need to read the block until the end, but
 199                  *   there is no data beyond it, which allows us to move
 200                  *   the write pointer to a new block.
 201                  */
 202                 if (cend == TTYINQ_DATASIZE || cend == ti->ti_end) {
 203                         /*
 204                          * Fast path: zero copy. Remove the first block,
 205                          * so we can unlock the TTY temporarily.
 206                          */
 207                         TTYINQ_REMOVE_HEAD(ti);
 208                         ti->ti_begin = 0;
 209
 210                         /*
 211                          * Because we remove the first block, we must
 212                          * fix up the block offsets.
 213                          */
 214 #define CORRECT_BLOCK(t) do {                   \
 215         if (t <= TTYINQ_DATASIZE)               \
 216                 t = 0;                          \
 217         else                                    \
 218                 t -= TTYINQ_DATASIZE;           \
 219 } while (0)
 220                         CORRECT_BLOCK(ti->ti_linestart);
 221                         CORRECT_BLOCK(ti->ti_reprint);
 222                         CORRECT_BLOCK(ti->ti_end);
 223 #undef CORRECT_BLOCK
 224
 225                         /*
 226                          * Temporary unlock and copy the data to
 227                          * userspace. We may need to flush trailing
 228                          * bytes, like EOF characters.
 229                          */
 230                         tty_unlock(tp);
 231                         error = uiomove(tib->tib_data + cbegin,
 232                             clen - flen, uio);
 233                         tty_lock(tp);
 234
 235                         /* Block can now be readded to the list. */
 236                         TTYINQ_RECYCLE(ti, tib);
 237                 } else {
 238                         char ob[TTYINQ_DATASIZE - 1];
 239
 240                         /*
 241                          * Slow path: store data in a temporary buffer.
 242                          */
 243                         memcpy(ob, tib->tib_data + cbegin, clen - flen);
 244                         ti->ti_begin += clen;
 245                         MPASS(ti->ti_begin < TTYINQ_DATASIZE);
 246
 247                         /* Temporary unlock and copy the data to userspace. */
 248                         tty_unlock(tp);
 249                         error = uiomove(ob, clen - flen, uio);
 250                         tty_lock(tp);
 251                 }
 252
 253                 if (error != 0)
 254                         return (error);
 255                 if (tty_gone(tp))
 256                         return (ENXIO);
 257         }
 258
 259         return (0);
 260 }
 261
 262 static __inline void
 263 ttyinq_set_quotes(struct ttyinq_block *tib, size_t offset,
 264     size_t length, int value)
 265 {
 266
 267         if (value) {
 268                 /* Set the bits. */
 269                 for (; length > 0; length--, offset++)
 270                         SETBIT(tib, offset);
 271         } else {
 272                 /* Unset the bits. */
 273                 for (; length > 0; length--, offset++)
 274                         CLRBIT(tib, offset);
 275         }
 276 }
 277
 278 size_t
 279 ttyinq_write(struct ttyinq *ti, const void *buf, size_t nbytes, int quote)
 280 {
 281         const char *cbuf = buf;
 282         struct ttyinq_block *tib;
 283         unsigned int boff;
 284         size_t l;
 285
 286         while (nbytes > 0) {
 287                 boff = ti->ti_end % TTYINQ_DATASIZE;
 288
 289                 if (ti->ti_end == 0) {
 290                         /* First time we're being used or drained. */
 291                         MPASS(ti->ti_begin == 0);
 292                         tib = ti->ti_firstblock;
 293                         if (tib == NULL) {
 294                                 /* Queue has no blocks. */
 295                                 break;
 296                         }
 297                         ti->ti_lastblock = tib;
 298                 } else if (boff == 0) {
 299                         /* We reached the end of this block on last write. */
 300                         tib = ti->ti_lastblock->tib_next;
 301                         if (tib == NULL) {
 302                                 /* We've reached the watermark. */
 303                                 break;
 304                         }
 305                         ti->ti_lastblock = tib;
 306                 } else {
 307                         tib = ti->ti_lastblock;
 308                 }
 309
 310                 /* Don't copy more than was requested. */
 311                 l = MIN(nbytes, TTYINQ_DATASIZE - boff);
 312                 MPASS(l > 0);
 313                 memcpy(tib->tib_data + boff, cbuf, l);
 314
 315                 /* Set the quoting bits for the proper region. */
 316                 ttyinq_set_quotes(tib, boff, l, quote);
 317
 318                 cbuf += l;
 319                 nbytes -= l;
 320                 ti->ti_end += l;
 321         }
 322
 323         return (cbuf - (const char *)buf);
 324 }
 325
 326 int
 327 ttyinq_write_nofrag(struct ttyinq *ti, const void *buf, size_t nbytes, int quote)
 328 {
 329         size_t ret;
 330
 331         if (ttyinq_bytesleft(ti) < nbytes)
 332                 return (-1);
 333
 334         /* We should always be able to write it back. */
 335         ret = ttyinq_write(ti, buf, nbytes, quote);
 336         MPASS(ret == nbytes);
 337
 338         return (0);
 339 }
 340
 341 void
 342 ttyinq_canonicalize(struct ttyinq *ti)
 343 {
 344
 345         ti->ti_linestart = ti->ti_reprint = ti->ti_end;
 346         ti->ti_startblock = ti->ti_reprintblock = ti->ti_lastblock;
 347 }
 348
 349 size_t
 350 ttyinq_findchar(struct ttyinq *ti, const char *breakc, size_t maxlen,
 351     char *lastc)
 352 {
 353         struct ttyinq_block *tib = ti->ti_firstblock;
 354         unsigned int boff = ti->ti_begin;
 355         unsigned int bend = MIN(MIN(TTYINQ_DATASIZE, ti->ti_linestart),
 356             ti->ti_begin + maxlen);
 357
 358         MPASS(maxlen > 0);
 359
 360         if (tib == NULL)
 361                 return (0);
 362
 363         while (boff < bend) {
 364                 if (strchr(breakc, tib->tib_data[boff]) && !GETBIT(tib, boff)) {
 365                         *lastc = tib->tib_data[boff];
 366                         return (boff - ti->ti_begin + 1);
 367                 }
 368                 boff++;
 369         }
 370
 371         /* Not found - just process the entire block. */
 372         return (bend - ti->ti_begin);
 373 }
 374
 375 void
 376 ttyinq_flush(struct ttyinq *ti)
 377 {
 378         struct ttyinq_block *tib;
 379
 380         ti->ti_begin = 0;
 381         ti->ti_linestart = 0;
 382         ti->ti_reprint = 0;
 383         ti->ti_end = 0;
 384
 385         /* Zero all data in the input queue to get rid of passwords. */
 386         if (ttyinq_flush_secure) {
 387                 for (tib = ti->ti_firstblock; tib != NULL; tib = tib->tib_next)
 388                         bzero(&tib->tib_data, sizeof tib->tib_data);
 389         }
 390 }
 391
 392 int
 393 ttyinq_peekchar(struct ttyinq *ti, char *c, int *quote)
 394 {
 395         unsigned int boff;
 396         struct ttyinq_block *tib = ti->ti_lastblock;
 397
 398         if (ti->ti_linestart == ti->ti_end)
 399                 return (-1);
 400
 401         MPASS(ti->ti_end > 0);
 402         boff = (ti->ti_end - 1) % TTYINQ_DATASIZE;
 403
 404         *c = tib->tib_data[boff];
 405         *quote = GETBIT(tib, boff);
 406
 407         return (0);
 408 }
 409
 410 void
 411 ttyinq_unputchar(struct ttyinq *ti)
 412 {
 413
 414         MPASS(ti->ti_linestart < ti->ti_end);
 415
 416         if (--ti->ti_end % TTYINQ_DATASIZE == 0) {
 417                 /* Roll back to the previous block. */
 418                 ti->ti_lastblock = ti->ti_lastblock->tib_prev;
 419                 /*
 420                  * This can only fail if we are unputchar()'ing the
 421                  * first character in the queue.
 422                  */
 423                 MPASS((ti->ti_lastblock == NULL) == (ti->ti_end == 0));
 424         }
 425 }
 426
 427 void
 428 ttyinq_reprintpos_set(struct ttyinq *ti)
 429 {
 430
 431         ti->ti_reprint = ti->ti_end;
 432         ti->ti_reprintblock = ti->ti_lastblock;
 433 }
 434
 435 void
 436 ttyinq_reprintpos_reset(struct ttyinq *ti)
 437 {
 438
 439         ti->ti_reprint = ti->ti_linestart;
 440         ti->ti_reprintblock = ti->ti_startblock;
 441 }
 442
 443 static void
 444 ttyinq_line_iterate(struct ttyinq *ti,
 445     ttyinq_line_iterator_t *iterator, void *data,
 446     unsigned int offset, struct ttyinq_block *tib)
 447 {
 448         unsigned int boff;
 449
 450         /* Use the proper block when we're at the queue head. */
 451         if (offset == 0)
 452                 tib = ti->ti_firstblock;
 453
 454         /* Iterate all characters and call the iterator function. */
 455         for (; offset < ti->ti_end; offset++) {
 456                 boff = offset % TTYINQ_DATASIZE;
 457                 MPASS(tib != NULL);
 458
 459                 /* Call back the iterator function. */
 460                 iterator(data, tib->tib_data[boff], GETBIT(tib, boff));
 461
 462                 /* Last byte iterated - go to the next block. */
 463                 if (boff == TTYINQ_DATASIZE - 1)
 464                         tib = tib->tib_next;
 465                 MPASS(tib != NULL);
 466         }
 467 }
 468
 469 void
 470 ttyinq_line_iterate_from_linestart(struct ttyinq *ti,
 471     ttyinq_line_iterator_t *iterator, void *data)
 472 {
 473
 474         ttyinq_line_iterate(ti, iterator, data,
 475             ti->ti_linestart, ti->ti_startblock);
 476 }
 477
 478 void
 479 ttyinq_line_iterate_from_reprintpos(struct ttyinq *ti,
 480     ttyinq_line_iterator_t *iterator, void *data)
 481 {
 482
 483         ttyinq_line_iterate(ti, iterator, data,
 484             ti->ti_reprint, ti->ti_reprintblock);
 485 }
 486
 487 static void
 488 ttyinq_startup(void *dummy)
 489 {
 490
 491         ttyinq_zone = uma_zcreate("ttyinq", sizeof(struct ttyinq_block),
 492             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 493 }
 494
 495 SYSINIT(ttyinq, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyinq_startup, NULL);