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 void
 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                 TTYINQ_INSERT_TAIL(ti, tib);
 138         }
 139 }
 140
 141 void
 142 ttyinq_free(struct ttyinq *ti)
 143 {
 144         struct ttyinq_block *tib;
 145
 146         ttyinq_flush(ti);
 147         ti->ti_quota = 0;
 148
 149         while ((tib = ti->ti_firstblock) != NULL) {
 150                 TTYINQ_REMOVE_HEAD(ti);
 151                 uma_zfree(ttyinq_zone, tib);
 152         }
 153
 154         MPASS(ti->ti_nblocks == 0);
 155 }
 156
 157 int
 158 ttyinq_read_uio(struct ttyinq *ti, struct tty *tp, struct uio *uio,
 159     size_t rlen, size_t flen)
 160 {
 161
 162         MPASS(rlen <= uio->uio_resid);
 163
 164         while (rlen > 0) {
 165                 int error;
 166                 struct ttyinq_block *tib;
 167                 size_t cbegin, cend, clen;
 168
 169                 /* See if there still is data. */
 170                 if (ti->ti_begin == ti->ti_linestart)
 171                         return (0);
 172                 tib = ti->ti_firstblock;
 173                 if (tib == NULL)
 174                         return (0);
 175
 176                 /*
 177                  * The end address should be the lowest of these three:
 178                  * - The write pointer
 179                  * - The blocksize - we can't read beyond the block
 180                  * - The end address if we could perform the full read
 181                  */
 182                 cbegin = ti->ti_begin;
 183                 cend = MIN(MIN(ti->ti_linestart, ti->ti_begin + rlen),
 184                     TTYINQ_DATASIZE);
 185                 clen = cend - cbegin;
 186                 MPASS(clen >= flen);
 187                 rlen -= clen;
 188
 189                 /*
 190                  * We can prevent buffering in some cases:
 191                  * - We need to read the block until the end.
 192                  * - We don't need to read the block until the end, but
 193                  *   there is no data beyond it, which allows us to move
 194                  *   the write pointer to a new block.
 195                  */
 196                 if (cend == TTYINQ_DATASIZE || cend == ti->ti_end) {
 197                         /*
 198                          * Fast path: zero copy. Remove the first block,
 199                          * so we can unlock the TTY temporarily.
 200                          */
 201                         TTYINQ_REMOVE_HEAD(ti);
 202                         ti->ti_begin = 0;
 203
 204                         /*
 205                          * Because we remove the first block, we must
 206                          * fix up the block offsets.
 207                          */
 208 #define CORRECT_BLOCK(t) do {                   \
 209         if (t <= TTYINQ_DATASIZE)               \
 210                 t = 0;                          \
 211         else                                    \
 212                 t -= TTYINQ_DATASIZE;           \
 213 } while (0)
 214                         CORRECT_BLOCK(ti->ti_linestart);
 215                         CORRECT_BLOCK(ti->ti_reprint);
 216                         CORRECT_BLOCK(ti->ti_end);
 217 #undef CORRECT_BLOCK
 218
 219                         /*
 220                          * Temporary unlock and copy the data to
 221                          * userspace. We may need to flush trailing
 222                          * bytes, like EOF characters.
 223                          */
 224                         tty_unlock(tp);
 225                         error = uiomove(tib->tib_data + cbegin,
 226                             clen - flen, uio);
 227                         tty_lock(tp);
 228
 229                         /* Block can now be readded to the list. */
 230                         TTYINQ_RECYCLE(ti, tib);
 231                 } else {
 232                         char ob[TTYINQ_DATASIZE - 1];
 233
 234                         /*
 235                          * Slow path: store data in a temporary buffer.
 236                          */
 237                         memcpy(ob, tib->tib_data + cbegin, clen - flen);
 238                         ti->ti_begin += clen;
 239                         MPASS(ti->ti_begin < TTYINQ_DATASIZE);
 240
 241                         /* Temporary unlock and copy the data to userspace. */
 242                         tty_unlock(tp);
 243                         error = uiomove(ob, clen - flen, uio);
 244                         tty_lock(tp);
 245                 }
 246
 247                 if (error != 0)
 248                         return (error);
 249                 if (tty_gone(tp))
 250                         return (ENXIO);
 251         }
 252
 253         return (0);
 254 }
 255
 256 static __inline void
 257 ttyinq_set_quotes(struct ttyinq_block *tib, size_t offset,
 258     size_t length, int value)
 259 {
 260
 261         if (value) {
 262                 /* Set the bits. */
 263                 for (; length > 0; length--, offset++)
 264                         SETBIT(tib, offset);
 265         } else {
 266                 /* Unset the bits. */
 267                 for (; length > 0; length--, offset++)
 268                         CLRBIT(tib, offset);
 269         }
 270 }
 271
 272 size_t
 273 ttyinq_write(struct ttyinq *ti, const void *buf, size_t nbytes, int quote)
 274 {
 275         const char *cbuf = buf;
 276         struct ttyinq_block *tib;
 277         unsigned int boff;
 278         size_t l;
 279
 280         while (nbytes > 0) {
 281                 boff = ti->ti_end % TTYINQ_DATASIZE;
 282
 283                 if (ti->ti_end == 0) {
 284                         /* First time we're being used or drained. */
 285                         MPASS(ti->ti_begin == 0);
 286                         tib = ti->ti_firstblock;
 287                         if (tib == NULL) {
 288                                 /* Queue has no blocks. */
 289                                 break;
 290                         }
 291                         ti->ti_lastblock = tib;
 292                 } else if (boff == 0) {
 293                         /* We reached the end of this block on last write. */
 294                         tib = ti->ti_lastblock->tib_next;
 295                         if (tib == NULL) {
 296                                 /* We've reached the watermark. */
 297                                 break;
 298                         }
 299                         ti->ti_lastblock = tib;
 300                 } else {
 301                         tib = ti->ti_lastblock;
 302                 }
 303
 304                 /* Don't copy more than was requested. */
 305                 l = MIN(nbytes, TTYINQ_DATASIZE - boff);
 306                 MPASS(l > 0);
 307                 memcpy(tib->tib_data + boff, cbuf, l);
 308
 309                 /* Set the quoting bits for the proper region. */
 310                 ttyinq_set_quotes(tib, boff, l, quote);
 311
 312                 cbuf += l;
 313                 nbytes -= l;
 314                 ti->ti_end += l;
 315         }
 316
 317         return (cbuf - (const char *)buf);
 318 }
 319
 320 int
 321 ttyinq_write_nofrag(struct ttyinq *ti, const void *buf, size_t nbytes, int quote)
 322 {
 323         size_t ret;
 324
 325         if (ttyinq_bytesleft(ti) < nbytes)
 326                 return (-1);
 327
 328         /* We should always be able to write it back. */
 329         ret = ttyinq_write(ti, buf, nbytes, quote);
 330         MPASS(ret == nbytes);
 331
 332         return (0);
 333 }
 334
 335 void
 336 ttyinq_canonicalize(struct ttyinq *ti)
 337 {
 338
 339         ti->ti_linestart = ti->ti_reprint = ti->ti_end;
 340         ti->ti_startblock = ti->ti_reprintblock = ti->ti_lastblock;
 341 }
 342
 343 size_t
 344 ttyinq_findchar(struct ttyinq *ti, const char *breakc, size_t maxlen,
 345     char *lastc)
 346 {
 347         struct ttyinq_block *tib = ti->ti_firstblock;
 348         unsigned int boff = ti->ti_begin;
 349         unsigned int bend = MIN(MIN(TTYINQ_DATASIZE, ti->ti_linestart),
 350             ti->ti_begin + maxlen);
 351
 352         MPASS(maxlen > 0);
 353
 354         if (tib == NULL)
 355                 return (0);
 356
 357         while (boff < bend) {
 358                 if (strchr(breakc, tib->tib_data[boff]) && !GETBIT(tib, boff)) {
 359                         *lastc = tib->tib_data[boff];
 360                         return (boff - ti->ti_begin + 1);
 361                 }
 362                 boff++;
 363         }
 364
 365         /* Not found - just process the entire block. */
 366         return (bend - ti->ti_begin);
 367 }
 368
 369 void
 370 ttyinq_flush(struct ttyinq *ti)
 371 {
 372         struct ttyinq_block *tib;
 373
 374         ti->ti_begin = 0;
 375         ti->ti_linestart = 0;
 376         ti->ti_reprint = 0;
 377         ti->ti_end = 0;
 378
 379         /* Zero all data in the input queue to get rid of passwords. */
 380         if (ttyinq_flush_secure) {
 381                 for (tib = ti->ti_firstblock; tib != NULL; tib = tib->tib_next)
 382                         bzero(&tib->tib_data, sizeof tib->tib_data);
 383         }
 384 }
 385
 386 int
 387 ttyinq_peekchar(struct ttyinq *ti, char *c, int *quote)
 388 {
 389         unsigned int boff;
 390         struct ttyinq_block *tib = ti->ti_lastblock;
 391
 392         if (ti->ti_linestart == ti->ti_end)
 393                 return (-1);
 394
 395         MPASS(ti->ti_end > 0);
 396         boff = (ti->ti_end - 1) % TTYINQ_DATASIZE;
 397
 398         *c = tib->tib_data[boff];
 399         *quote = GETBIT(tib, boff);
 400
 401         return (0);
 402 }
 403
 404 void
 405 ttyinq_unputchar(struct ttyinq *ti)
 406 {
 407
 408         MPASS(ti->ti_linestart < ti->ti_end);
 409
 410         if (--ti->ti_end % TTYINQ_DATASIZE == 0) {
 411                 /* Roll back to the previous block. */
 412                 ti->ti_lastblock = ti->ti_lastblock->tib_prev;
 413                 /*
 414                  * This can only fail if we are unputchar()'ing the
 415                  * first character in the queue.
 416                  */
 417                 MPASS((ti->ti_lastblock == NULL) == (ti->ti_end == 0));
 418         }
 419 }
 420
 421 void
 422 ttyinq_reprintpos_set(struct ttyinq *ti)
 423 {
 424
 425         ti->ti_reprint = ti->ti_end;
 426         ti->ti_reprintblock = ti->ti_lastblock;
 427 }
 428
 429 void
 430 ttyinq_reprintpos_reset(struct ttyinq *ti)
 431 {
 432
 433         ti->ti_reprint = ti->ti_linestart;
 434         ti->ti_reprintblock = ti->ti_startblock;
 435 }
 436
 437 static void
 438 ttyinq_line_iterate(struct ttyinq *ti,
 439     ttyinq_line_iterator_t *iterator, void *data,
 440     unsigned int offset, struct ttyinq_block *tib)
 441 {
 442         unsigned int boff;
 443
 444         /* Use the proper block when we're at the queue head. */
 445         if (offset == 0)
 446                 tib = ti->ti_firstblock;
 447
 448         /* Iterate all characters and call the iterator function. */
 449         for (; offset < ti->ti_end; offset++) {
 450                 boff = offset % TTYINQ_DATASIZE;
 451                 MPASS(tib != NULL);
 452
 453                 /* Call back the iterator function. */
 454                 iterator(data, tib->tib_data[boff], GETBIT(tib, boff));
 455
 456                 /* Last byte iterated - go to the next block. */
 457                 if (boff == TTYINQ_DATASIZE - 1)
 458                         tib = tib->tib_next;
 459                 MPASS(tib != NULL);
 460         }
 461 }
 462
 463 void
 464 ttyinq_line_iterate_from_linestart(struct ttyinq *ti,
 465     ttyinq_line_iterator_t *iterator, void *data)
 466 {
 467
 468         ttyinq_line_iterate(ti, iterator, data,
 469             ti->ti_linestart, ti->ti_startblock);
 470 }
 471
 472 void
 473 ttyinq_line_iterate_from_reprintpos(struct ttyinq *ti,
 474     ttyinq_line_iterator_t *iterator, void *data)
 475 {
 476
 477         ttyinq_line_iterate(ti, iterator, data,
 478             ti->ti_reprint, ti->ti_reprintblock);
 479 }
 480
 481 static void
 482 ttyinq_startup(void *dummy)
 483 {
 484
 485         ttyinq_zone = uma_zcreate("ttyinq", sizeof(struct ttyinq_block),
 486             NULL, NULL, NULL, NULL, UMA_ALIGN_PTR, 0);
 487 }
 488
 489 SYSINIT(ttyinq, SI_SUB_DRIVERS, SI_ORDER_FIRST, ttyinq_startup, NULL);