The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/kern/tty_ttydisc.c

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    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: releng/8.0/sys/kern/tty_ttydisc.c 196036 2009-08-02 14:25:26Z ed $");
   32 
   33 #include <sys/param.h>
   34 #include <sys/fcntl.h>
   35 #include <sys/filio.h>
   36 #include <sys/kernel.h>
   37 #include <sys/signal.h>
   38 #include <sys/sysctl.h>
   39 #include <sys/systm.h>
   40 #include <sys/tty.h>
   41 #include <sys/ttycom.h>
   42 #include <sys/ttydefaults.h>
   43 #include <sys/uio.h>
   44 #include <sys/vnode.h>
   45 
   46 /*
   47  * Standard TTYDISC `termios' line discipline.
   48  */
   49 
   50 /* Statistics. */
   51 static unsigned long tty_nin = 0;
   52 SYSCTL_ULONG(_kern, OID_AUTO, tty_nin, CTLFLAG_RD,
   53         &tty_nin, 0, "Total amount of bytes received");
   54 static unsigned long tty_nout = 0;
   55 SYSCTL_ULONG(_kern, OID_AUTO, tty_nout, CTLFLAG_RD,
   56         &tty_nout, 0, "Total amount of bytes transmitted");
   57 
   58 /* termios comparison macro's. */
   59 #define CMP_CC(v,c) (tp->t_termios.c_cc[v] != _POSIX_VDISABLE && \
   60                         tp->t_termios.c_cc[v] == (c))
   61 #define CMP_FLAG(field,opt) (tp->t_termios.c_ ## field ## flag & (opt))
   62 
   63 /* Characters that cannot be modified through c_cc. */
   64 #define CTAB    '\t'
   65 #define CNL     '\n'
   66 #define CCR     '\r'
   67 
   68 /* Character is a control character. */
   69 #define CTL_VALID(c)    ((c) == 0x7f || (unsigned char)(c) < 0x20)
   70 /* Control character should be processed on echo. */
   71 #define CTL_ECHO(c,q)   (!(q) && ((c) == CERASE2 || (c) == CTAB || \
   72     (c) == CNL || (c) == CCR))
   73 /* Control character should be printed using ^X notation. */
   74 #define CTL_PRINT(c,q)  ((c) == 0x7f || ((unsigned char)(c) < 0x20 && \
   75     ((q) || ((c) != CTAB && (c) != CNL))))
   76 /* Character is whitespace. */
   77 #define CTL_WHITE(c)    ((c) == ' ' || (c) == CTAB)
   78 /* Character is alphanumeric. */
   79 #define CTL_ALNUM(c)    (((c) >= '' && (c) <= '9') || \
   80     ((c) >= 'a' && (c) <= 'z') || ((c) >= 'A' && (c) <= 'Z'))
   81 
   82 #define TTY_STACKBUF    256
   83 
   84 void
   85 ttydisc_open(struct tty *tp)
   86 {
   87         ttydisc_optimize(tp);
   88 }
   89 
   90 void
   91 ttydisc_close(struct tty *tp)
   92 {
   93 
   94         /* Clean up our flags when leaving the discipline. */
   95         tp->t_flags &= ~(TF_STOPPED|TF_HIWAT|TF_ZOMBIE);
   96 
   97         /* POSIX states we should flush when close() is called. */
   98         ttyinq_flush(&tp->t_inq);
   99         ttyoutq_flush(&tp->t_outq);
  100 
  101         if (!tty_gone(tp)) {
  102                 ttydevsw_inwakeup(tp);
  103                 ttydevsw_outwakeup(tp);
  104         }
  105 
  106         if (ttyhook_hashook(tp, close))
  107                 ttyhook_close(tp);
  108 }
  109 
  110 static int
  111 ttydisc_read_canonical(struct tty *tp, struct uio *uio, int ioflag)
  112 {
  113         char breakc[4] = { CNL }; /* enough to hold \n, VEOF and VEOL. */
  114         int error;
  115         size_t clen, flen = 0, n = 1;
  116         unsigned char lastc = _POSIX_VDISABLE;
  117 
  118 #define BREAK_ADD(c) do { \
  119         if (tp->t_termios.c_cc[c] != _POSIX_VDISABLE)   \
  120                 breakc[n++] = tp->t_termios.c_cc[c];    \
  121 } while (0)
  122         /* Determine which characters we should trigger on. */
  123         BREAK_ADD(VEOF);
  124         BREAK_ADD(VEOL);
  125 #undef BREAK_ADD
  126         breakc[n] = '\0';
  127 
  128         do {
  129                 /*
  130                  * Quite a tricky case: unlike the old TTY
  131                  * implementation, this implementation copies data back
  132                  * to userspace in large chunks. Unfortunately, we can't
  133                  * calculate the line length on beforehand if it crosses
  134                  * ttyinq_block boundaries, because multiple reads could
  135                  * then make this code read beyond the newline.
  136                  *
  137                  * This is why we limit the read to:
  138                  * - The size the user has requested
  139                  * - The blocksize (done in tty_inq.c)
  140                  * - The amount of bytes until the newline
  141                  *
  142                  * This causes the line length to be recalculated after
  143                  * each block has been copied to userspace. This will
  144                  * cause the TTY layer to return data in chunks using
  145                  * the blocksize (except the first and last blocks).
  146                  */
  147                 clen = ttyinq_findchar(&tp->t_inq, breakc, uio->uio_resid,
  148                     &lastc);
  149 
  150                 /* No more data. */
  151                 if (clen == 0) {
  152                         if (ioflag & IO_NDELAY)
  153                                 return (EWOULDBLOCK);
  154                         else if (tp->t_flags & TF_ZOMBIE)
  155                                 return (0);
  156 
  157                         error = tty_wait(tp, &tp->t_inwait);
  158                         if (error)
  159                                 return (error);
  160                         continue;
  161                 }
  162 
  163                 /* Don't send the EOF char back to userspace. */
  164                 if (CMP_CC(VEOF, lastc))
  165                         flen = 1;
  166 
  167                 MPASS(flen <= clen);
  168 
  169                 /* Read and throw away the EOF character. */
  170                 error = ttyinq_read_uio(&tp->t_inq, tp, uio, clen, flen);
  171                 if (error)
  172                         return (error);
  173 
  174         } while (uio->uio_resid > 0 && lastc == _POSIX_VDISABLE);
  175 
  176         return (0);
  177 }
  178 
  179 static int
  180 ttydisc_read_raw_no_timer(struct tty *tp, struct uio *uio, int ioflag)
  181 {
  182         size_t vmin = tp->t_termios.c_cc[VMIN];
  183         int oresid = uio->uio_resid;
  184         int error;
  185 
  186         MPASS(tp->t_termios.c_cc[VTIME] == 0);
  187 
  188         /*
  189          * This routine implements the easy cases of read()s while in
  190          * non-canonical mode, namely case B and D, where we don't have
  191          * any timers at all.
  192          */
  193 
  194         for (;;) {
  195                 error = ttyinq_read_uio(&tp->t_inq, tp, uio,
  196                     uio->uio_resid, 0);
  197                 if (error)
  198                         return (error);
  199                 if (uio->uio_resid == 0 || (oresid - uio->uio_resid) >= vmin)
  200                         return (0);
  201 
  202                 /* We have to wait for more. */
  203                 if (ioflag & IO_NDELAY)
  204                         return (EWOULDBLOCK);
  205                 else if (tp->t_flags & TF_ZOMBIE)
  206                         return (0);
  207 
  208                 error = tty_wait(tp, &tp->t_inwait);
  209                 if (error)
  210                         return (error);
  211         }
  212 }
  213 
  214 static int
  215 ttydisc_read_raw_read_timer(struct tty *tp, struct uio *uio, int ioflag,
  216     int oresid)
  217 {
  218         size_t vmin = MAX(tp->t_termios.c_cc[VMIN], 1);
  219         unsigned int vtime = tp->t_termios.c_cc[VTIME];
  220         struct timeval end, now, left;
  221         int error, hz;
  222 
  223         MPASS(tp->t_termios.c_cc[VTIME] != 0);
  224 
  225         /* Determine when the read should be expired. */
  226         end.tv_sec = vtime / 10;
  227         end.tv_usec = (vtime % 10) * 100000;
  228         getmicrotime(&now);
  229         timevaladd(&end, &now);
  230 
  231         for (;;) {
  232                 error = ttyinq_read_uio(&tp->t_inq, tp, uio,
  233                     uio->uio_resid, 0);
  234                 if (error)
  235                         return (error);
  236                 if (uio->uio_resid == 0 || (oresid - uio->uio_resid) >= vmin)
  237                         return (0);
  238 
  239                 /* Calculate how long we should wait. */
  240                 getmicrotime(&now);
  241                 if (timevalcmp(&now, &end, >))
  242                         return (0);
  243                 left = end;
  244                 timevalsub(&left, &now);
  245                 hz = tvtohz(&left);
  246 
  247                 /*
  248                  * We have to wait for more. If the timer expires, we
  249                  * should return a 0-byte read.
  250                  */
  251                 if (ioflag & IO_NDELAY)
  252                         return (EWOULDBLOCK);
  253                 else if (tp->t_flags & TF_ZOMBIE)
  254                         return (0);
  255 
  256                 error = tty_timedwait(tp, &tp->t_inwait, hz);
  257                 if (error)
  258                         return (error == EWOULDBLOCK ? 0 : error);
  259         }
  260 
  261         return (0);
  262 }
  263 
  264 static int
  265 ttydisc_read_raw_interbyte_timer(struct tty *tp, struct uio *uio, int ioflag)
  266 {
  267         size_t vmin = tp->t_termios.c_cc[VMIN];
  268         int oresid = uio->uio_resid;
  269         int error;
  270 
  271         MPASS(tp->t_termios.c_cc[VMIN] != 0);
  272         MPASS(tp->t_termios.c_cc[VTIME] != 0);
  273         
  274         /*
  275          * When using the interbyte timer, the timer should be started
  276          * after the first byte has been received. We just call into the
  277          * generic read timer code after we've received the first byte.
  278          */
  279         
  280         for (;;) {
  281                 error = ttyinq_read_uio(&tp->t_inq, tp, uio,
  282                     uio->uio_resid, 0);
  283                 if (error)
  284                         return (error);
  285                 if (uio->uio_resid == 0 || (oresid - uio->uio_resid) >= vmin)
  286                         return (0);
  287 
  288                 /*
  289                  * Not enough data, but we did receive some, which means
  290                  * we'll now start using the interbyte timer.
  291                  */
  292                 if (oresid != uio->uio_resid)
  293                         break;
  294 
  295                 /* We have to wait for more. */
  296                 if (ioflag & IO_NDELAY)
  297                         return (EWOULDBLOCK);
  298                 else if (tp->t_flags & TF_ZOMBIE)
  299                         return (0);
  300 
  301                 error = tty_wait(tp, &tp->t_inwait);
  302                 if (error)
  303                         return (error);
  304         }
  305 
  306         return ttydisc_read_raw_read_timer(tp, uio, ioflag, oresid);
  307 }
  308 
  309 int
  310 ttydisc_read(struct tty *tp, struct uio *uio, int ioflag)
  311 {
  312         int error;
  313 
  314         tty_lock_assert(tp, MA_OWNED);
  315 
  316         if (uio->uio_resid == 0)
  317                 return (0);
  318 
  319         if (CMP_FLAG(l, ICANON))
  320                 error = ttydisc_read_canonical(tp, uio, ioflag);
  321         else if (tp->t_termios.c_cc[VTIME] == 0)
  322                 error = ttydisc_read_raw_no_timer(tp, uio, ioflag);
  323         else if (tp->t_termios.c_cc[VMIN] == 0)
  324                 error = ttydisc_read_raw_read_timer(tp, uio, ioflag,
  325                     uio->uio_resid);
  326         else
  327                 error = ttydisc_read_raw_interbyte_timer(tp, uio, ioflag);
  328 
  329         if (ttyinq_bytesleft(&tp->t_inq) >= tp->t_inlow ||
  330             ttyinq_bytescanonicalized(&tp->t_inq) == 0) {
  331                 /* Unset the input watermark when we've got enough space. */
  332                 tty_hiwat_in_unblock(tp);
  333         }
  334         
  335         return (error);
  336 }
  337 
  338 static __inline unsigned int
  339 ttydisc_findchar(const char *obstart, unsigned int oblen)
  340 {
  341         const char *c = obstart;
  342 
  343         while (oblen--) {
  344                 if (CTL_VALID(*c))
  345                         break;
  346                 c++;
  347         }
  348 
  349         return (c - obstart);
  350 }
  351 
  352 static int
  353 ttydisc_write_oproc(struct tty *tp, char c)
  354 {
  355         unsigned int scnt, error;
  356 
  357         MPASS(CMP_FLAG(o, OPOST));
  358         MPASS(CTL_VALID(c));
  359 
  360 #define PRINT_NORMAL() ttyoutq_write_nofrag(&tp->t_outq, &c, 1)
  361         switch (c) {
  362         case CEOF:
  363                 /* End-of-text dropping. */
  364                 if (CMP_FLAG(o, ONOEOT))
  365                         return (0);
  366                 return PRINT_NORMAL();
  367 
  368         case CERASE2:
  369                 /* Handle backspace to fix tab expansion. */
  370                 if (PRINT_NORMAL() != 0)
  371                         return (-1);
  372                 if (tp->t_column > 0)
  373                         tp->t_column--;
  374                 return (0);
  375 
  376         case CTAB:
  377                 /* Tab expansion. */
  378                 scnt = 8 - (tp->t_column & 7);
  379                 if (CMP_FLAG(o, TAB3)) {
  380                         error = ttyoutq_write_nofrag(&tp->t_outq,
  381                             "        ", scnt);
  382                 } else {
  383                         error = PRINT_NORMAL();
  384                 }
  385                 if (error)
  386                         return (-1);
  387 
  388                 tp->t_column += scnt;
  389                 MPASS((tp->t_column % 8) == 0);
  390                 return (0);
  391 
  392         case CNL:
  393                 /* Newline conversion. */
  394                 if (CMP_FLAG(o, ONLCR)) {
  395                         /* Convert \n to \r\n. */
  396                         error = ttyoutq_write_nofrag(&tp->t_outq, "\r\n", 2);
  397                 } else {
  398                         error = PRINT_NORMAL();
  399                 }
  400                 if (error)
  401                         return (-1);
  402 
  403                 if (CMP_FLAG(o, ONLCR|ONLRET)) {
  404                         tp->t_column = tp->t_writepos = 0;
  405                         ttyinq_reprintpos_set(&tp->t_inq);
  406                 }
  407                 return (0);
  408 
  409         case CCR:
  410                 /* Carriage return to newline conversion. */
  411                 if (CMP_FLAG(o, OCRNL))
  412                         c = CNL;
  413                 /* Omit carriage returns on column 0. */
  414                 if (CMP_FLAG(o, ONOCR) && tp->t_column == 0)
  415                         return (0);
  416                 if (PRINT_NORMAL() != 0)
  417                         return (-1);
  418 
  419                 tp->t_column = tp->t_writepos = 0;
  420                 ttyinq_reprintpos_set(&tp->t_inq);
  421                 return (0);
  422         }
  423 
  424         /*
  425          * Invisible control character. Print it, but don't
  426          * increase the column count.
  427          */
  428         return PRINT_NORMAL();
  429 #undef PRINT_NORMAL
  430 }
  431 
  432 /*
  433  * Just like the old TTY implementation, we need to copy data in chunks
  434  * into a temporary buffer. One of the reasons why we need to do this,
  435  * is because output processing (only TAB3 though) may allow the buffer
  436  * to grow eight times.
  437  */
  438 int
  439 ttydisc_write(struct tty *tp, struct uio *uio, int ioflag)
  440 {
  441         char ob[TTY_STACKBUF];
  442         char *obstart;
  443         int error = 0;
  444         unsigned int oblen = 0;
  445 
  446         tty_lock_assert(tp, MA_OWNED);
  447 
  448         if (tp->t_flags & TF_ZOMBIE)
  449                 return (EIO);
  450 
  451         /*
  452          * We don't need to check whether the process is the foreground
  453          * process group or if we have a carrier. This is already done
  454          * in ttydev_write().
  455          */
  456 
  457         while (uio->uio_resid > 0) {
  458                 unsigned int nlen;
  459 
  460                 MPASS(oblen == 0);
  461 
  462                 /* Step 1: read data. */
  463                 obstart = ob;
  464                 nlen = MIN(uio->uio_resid, sizeof ob);
  465                 tty_unlock(tp);
  466                 error = uiomove(ob, nlen, uio);
  467                 tty_lock(tp);
  468                 if (error != 0)
  469                         break;
  470                 oblen = nlen;
  471 
  472                 if (tty_gone(tp)) {
  473                         error = ENXIO;
  474                         break;
  475                 }
  476 
  477                 MPASS(oblen > 0);
  478 
  479                 /* Step 2: process data. */
  480                 do {
  481                         unsigned int plen, wlen;
  482 
  483                         /* Search for special characters for post processing. */
  484                         if (CMP_FLAG(o, OPOST)) {
  485                                 plen = ttydisc_findchar(obstart, oblen);
  486                         } else {
  487                                 plen = oblen;
  488                         }
  489 
  490                         if (plen == 0) {
  491                                 /*
  492                                  * We're going to process a character
  493                                  * that needs processing
  494                                  */
  495                                 if (ttydisc_write_oproc(tp, *obstart) == 0) {
  496                                         obstart++;
  497                                         oblen--;
  498 
  499                                         tp->t_writepos = tp->t_column;
  500                                         ttyinq_reprintpos_set(&tp->t_inq);
  501                                         continue;
  502                                 }
  503                         } else {
  504                                 /* We're going to write regular data. */
  505                                 wlen = ttyoutq_write(&tp->t_outq, obstart, plen);
  506                                 obstart += wlen;
  507                                 oblen -= wlen;
  508                                 tp->t_column += wlen;
  509 
  510                                 tp->t_writepos = tp->t_column;
  511                                 ttyinq_reprintpos_set(&tp->t_inq);
  512 
  513                                 if (wlen == plen)
  514                                         continue;
  515                         }
  516 
  517                         /* Watermark reached. Try to sleep. */
  518                         tp->t_flags |= TF_HIWAT_OUT;
  519 
  520                         if (ioflag & IO_NDELAY) {
  521                                 error = EWOULDBLOCK;
  522                                 goto done;
  523                         }
  524                         
  525                         /*
  526                          * The driver may write back the data
  527                          * synchronously. Be sure to check the high
  528                          * water mark before going to sleep.
  529                          */
  530                         ttydevsw_outwakeup(tp);
  531                         if ((tp->t_flags & TF_HIWAT_OUT) == 0)
  532                                 continue;
  533 
  534                         error = tty_wait(tp, &tp->t_outwait);
  535                         if (error)
  536                                 goto done;
  537 
  538                         if (tp->t_flags & TF_ZOMBIE) {
  539                                 error = EIO;
  540                                 goto done;
  541                         }
  542                 } while (oblen > 0);
  543         }
  544 
  545 done:
  546         if (!tty_gone(tp))
  547                 ttydevsw_outwakeup(tp);
  548 
  549         /*
  550          * Add the amount of bytes that we didn't process back to the
  551          * uio counters. We need to do this to make sure write() doesn't
  552          * count the bytes we didn't store in the queue.
  553          */
  554         uio->uio_resid += oblen;
  555         return (error);
  556 }
  557 
  558 void
  559 ttydisc_optimize(struct tty *tp)
  560 {
  561         tty_lock_assert(tp, MA_OWNED);
  562 
  563         if (ttyhook_hashook(tp, rint_bypass)) {
  564                 tp->t_flags |= TF_BYPASS;
  565         } else if (ttyhook_hashook(tp, rint)) {
  566                 tp->t_flags &= ~TF_BYPASS;
  567         } else if (!CMP_FLAG(i, ICRNL|IGNCR|IMAXBEL|INLCR|ISTRIP|IXON) &&
  568             (!CMP_FLAG(i, BRKINT) || CMP_FLAG(i, IGNBRK)) &&
  569             (!CMP_FLAG(i, PARMRK) ||
  570                 CMP_FLAG(i, IGNPAR|IGNBRK) == (IGNPAR|IGNBRK)) &&
  571             !CMP_FLAG(l, ECHO|ICANON|IEXTEN|ISIG|PENDIN)) {
  572                 tp->t_flags |= TF_BYPASS;
  573         } else {
  574                 tp->t_flags &= ~TF_BYPASS;
  575         }
  576 }
  577 
  578 void
  579 ttydisc_modem(struct tty *tp, int open)
  580 {
  581 
  582         tty_lock_assert(tp, MA_OWNED);
  583 
  584         if (open)
  585                 cv_broadcast(&tp->t_dcdwait);
  586         
  587         /*
  588          * Ignore modem status lines when CLOCAL is turned on, but don't
  589          * enter the zombie state when the TTY isn't opened, because
  590          * that would cause the TTY to be in zombie state after being
  591          * opened.
  592          */
  593         if (!tty_opened(tp) || CMP_FLAG(c, CLOCAL))
  594                 return;
  595 
  596         if (open == 0) {
  597                 /*
  598                  * Lost carrier.
  599                  */
  600                 tp->t_flags |= TF_ZOMBIE;
  601 
  602                 tty_signal_sessleader(tp, SIGHUP);
  603                 tty_flush(tp, FREAD|FWRITE);
  604         } else {
  605                 /*
  606                  * Carrier is back again.
  607                  */
  608 
  609                 /* XXX: what should we do here? */
  610         }
  611 }
  612 
  613 static int
  614 ttydisc_echo_force(struct tty *tp, char c, int quote)
  615 {
  616 
  617         if (CMP_FLAG(o, OPOST) && CTL_ECHO(c, quote)) {
  618                 /*
  619                  * Only perform postprocessing when OPOST is turned on
  620                  * and the character is an unquoted BS/TB/NL/CR.
  621                  */
  622                 return ttydisc_write_oproc(tp, c);
  623         } else if (CMP_FLAG(l, ECHOCTL) && CTL_PRINT(c, quote)) {
  624                 /*
  625                  * Only use ^X notation when ECHOCTL is turned on and
  626                  * we've got an quoted control character.
  627                  */
  628                 char ob[2] = { '^', '?' };
  629 
  630                 /* Print ^X notation. */
  631                 if (c != 0x7f)
  632                         ob[1] = c + 'A' - 1;
  633 
  634                 tp->t_column += 2;
  635                 return ttyoutq_write_nofrag(&tp->t_outq, ob, 2);
  636         } else {
  637                 /* Can just be printed. */
  638                 tp->t_column++;
  639                 return ttyoutq_write_nofrag(&tp->t_outq, &c, 1);
  640         }
  641 }
  642 
  643 static int
  644 ttydisc_echo(struct tty *tp, char c, int quote)
  645 {
  646 
  647         /*
  648          * Only echo characters when ECHO is turned on, or ECHONL when
  649          * the character is an unquoted newline.
  650          */
  651         if (!CMP_FLAG(l, ECHO) &&
  652             (!CMP_FLAG(l, ECHONL) || c != CNL || quote))
  653                 return (0);
  654 
  655         return ttydisc_echo_force(tp, c, quote);
  656 }
  657 
  658 
  659 static void
  660 ttydisc_reprint_char(void *d, char c, int quote)
  661 {
  662         struct tty *tp = d;
  663 
  664         ttydisc_echo(tp, c, quote);
  665 }
  666 
  667 static void
  668 ttydisc_reprint(struct tty *tp)
  669 {
  670         cc_t c;
  671 
  672         /* Print  ^R\n, followed by the line. */
  673         c = tp->t_termios.c_cc[VREPRINT];
  674         if (c != _POSIX_VDISABLE)
  675                 ttydisc_echo(tp, c, 0);
  676         ttydisc_echo(tp, CNL, 0);
  677         ttyinq_reprintpos_reset(&tp->t_inq);
  678 
  679         ttyinq_line_iterate_from_linestart(&tp->t_inq, ttydisc_reprint_char, tp);
  680 }
  681 
  682 struct ttydisc_recalc_length {
  683         struct tty *tp;
  684         unsigned int curlen;
  685 };
  686 
  687 static void
  688 ttydisc_recalc_charlength(void *d, char c, int quote)
  689 {
  690         struct ttydisc_recalc_length *data = d;
  691         struct tty *tp = data->tp;
  692 
  693         if (CTL_PRINT(c, quote)) {
  694                 if (CMP_FLAG(l, ECHOCTL))
  695                         data->curlen += 2;
  696         } else if (c == CTAB) {
  697                 data->curlen += 8 - (data->curlen & 7);
  698         } else {
  699                 data->curlen++;
  700         }
  701 }
  702 
  703 static unsigned int
  704 ttydisc_recalc_linelength(struct tty *tp)
  705 {
  706         struct ttydisc_recalc_length data = { tp, tp->t_writepos };
  707 
  708         ttyinq_line_iterate_from_reprintpos(&tp->t_inq,
  709             ttydisc_recalc_charlength, &data);
  710         return (data.curlen);
  711 }
  712 
  713 static int
  714 ttydisc_rubchar(struct tty *tp)
  715 {
  716         char c;
  717         int quote;
  718         unsigned int prevpos, tablen;
  719 
  720         if (ttyinq_peekchar(&tp->t_inq, &c, &quote) != 0)
  721                 return (-1);
  722         ttyinq_unputchar(&tp->t_inq);
  723 
  724         if (CMP_FLAG(l, ECHO)) {
  725                 /*
  726                  * Remove the character from the screen. This is even
  727                  * safe for characters that span multiple characters
  728                  * (tabs, quoted, etc).
  729                  */
  730                 if (tp->t_writepos >= tp->t_column) {
  731                         /* Retype the sentence. */
  732                         ttydisc_reprint(tp);
  733                 } else if (CMP_FLAG(l, ECHOE)) {
  734                         if (CTL_PRINT(c, quote)) {
  735                                 /* Remove ^X formatted chars. */
  736                                 if (CMP_FLAG(l, ECHOCTL)) {
  737                                         tp->t_column -= 2;
  738                                         ttyoutq_write_nofrag(&tp->t_outq,
  739                                             "\b\b  \b\b", 6);
  740                                 }
  741                         } else if (c == ' ') {
  742                                 /* Space character needs no rubbing. */
  743                                 tp->t_column -= 1;
  744                                 ttyoutq_write_nofrag(&tp->t_outq, "\b", 1);
  745                         } else if (c == CTAB) {
  746                                 /*
  747                                  * Making backspace work with tabs is
  748                                  * quite hard. Recalculate the length of
  749                                  * this character and remove it.
  750                                  *
  751                                  * Because terminal settings could be
  752                                  * changed while the line is being
  753                                  * inserted, the calculations don't have
  754                                  * to be correct. Make sure we keep the
  755                                  * tab length within proper bounds.
  756                                  */
  757                                 prevpos = ttydisc_recalc_linelength(tp);
  758                                 if (prevpos >= tp->t_column)
  759                                         tablen = 1;
  760                                 else
  761                                         tablen = tp->t_column - prevpos;
  762                                 if (tablen > 8)
  763                                         tablen = 8;
  764 
  765                                 tp->t_column = prevpos;
  766                                 ttyoutq_write_nofrag(&tp->t_outq,
  767                                     "\b\b\b\b\b\b\b\b", tablen);
  768                                 return (0);
  769                         } else {
  770                                 /*
  771                                  * Remove a regular character by
  772                                  * punching a space over it.
  773                                  */
  774                                 tp->t_column -= 1;
  775                                 ttyoutq_write_nofrag(&tp->t_outq, "\b \b", 3);
  776                         }
  777                 } else {
  778                         /* Don't print spaces. */
  779                         ttydisc_echo(tp, tp->t_termios.c_cc[VERASE], 0);
  780                 }
  781         }
  782 
  783         return (0);
  784 }
  785 
  786 static void
  787 ttydisc_rubword(struct tty *tp)
  788 {
  789         char c;
  790         int quote, alnum;
  791 
  792         /* Strip whitespace first. */
  793         for (;;) {
  794                 if (ttyinq_peekchar(&tp->t_inq, &c, &quote) != 0)
  795                         return;
  796                 if (!CTL_WHITE(c))
  797                         break;
  798                 ttydisc_rubchar(tp);
  799         }
  800 
  801         /*
  802          * Record whether the last character from the previous iteration
  803          * was alphanumeric or not. We need this to implement ALTWERASE.
  804          */
  805         alnum = CTL_ALNUM(c);
  806         for (;;) {
  807                 ttydisc_rubchar(tp);
  808 
  809                 if (ttyinq_peekchar(&tp->t_inq, &c, &quote) != 0)
  810                         return;
  811                 if (CTL_WHITE(c))
  812                         return;
  813                 if (CMP_FLAG(l, ALTWERASE) && CTL_ALNUM(c) != alnum)
  814                         return;
  815         }
  816 }
  817 
  818 int
  819 ttydisc_rint(struct tty *tp, char c, int flags)
  820 {
  821         int signal, quote = 0;
  822         char ob[3] = { 0xff, 0x00 };
  823         size_t ol;
  824 
  825         tty_lock_assert(tp, MA_OWNED);
  826 
  827         atomic_add_long(&tty_nin, 1);
  828 
  829         if (ttyhook_hashook(tp, rint))
  830                 return ttyhook_rint(tp, c, flags);
  831         
  832         if (tp->t_flags & TF_BYPASS)
  833                 goto processed;
  834 
  835         if (flags) {
  836                 if (flags & TRE_BREAK) {
  837                         if (CMP_FLAG(i, IGNBRK)) {
  838                                 /* Ignore break characters. */
  839                                 return (0);
  840                         } else if (CMP_FLAG(i, BRKINT)) {
  841                                 /* Generate SIGINT on break. */
  842                                 tty_flush(tp, FREAD|FWRITE);
  843                                 tty_signal_pgrp(tp, SIGINT);
  844                                 return (0);
  845                         } else {
  846                                 /* Just print it. */
  847                                 goto parmrk;
  848                         }
  849                 } else if (flags & TRE_FRAMING ||
  850                     (flags & TRE_PARITY && CMP_FLAG(i, INPCK))) {
  851                         if (CMP_FLAG(i, IGNPAR)) {
  852                                 /* Ignore bad characters. */
  853                                 return (0);
  854                         } else {
  855                                 /* Just print it. */
  856                                 goto parmrk;
  857                         }
  858                 }
  859         }
  860 
  861         /* Allow any character to perform a wakeup. */
  862         if (CMP_FLAG(i, IXANY))
  863                 tp->t_flags &= ~TF_STOPPED;
  864 
  865         /* Remove the top bit. */
  866         if (CMP_FLAG(i, ISTRIP))
  867                 c &= ~0x80;
  868 
  869         /* Skip input processing when we want to print it literally. */
  870         if (tp->t_flags & TF_LITERAL) {
  871                 tp->t_flags &= ~TF_LITERAL;
  872                 quote = 1;
  873                 goto processed;
  874         }
  875 
  876         /* Special control characters that are implementation dependent. */
  877         if (CMP_FLAG(l, IEXTEN)) {
  878                 /* Accept the next character as literal. */
  879                 if (CMP_CC(VLNEXT, c)) {
  880                         if (CMP_FLAG(l, ECHO)) {
  881                                 if (CMP_FLAG(l, ECHOE))
  882                                         ttyoutq_write_nofrag(&tp->t_outq, "^\b", 2);
  883                                 else
  884                                         ttydisc_echo(tp, c, 0);
  885                         }
  886                         tp->t_flags |= TF_LITERAL;
  887                         return (0);
  888                 }
  889         }
  890 
  891         /*
  892          * Handle signal processing.
  893          */
  894         if (CMP_FLAG(l, ISIG)) {
  895                 if (CMP_FLAG(l, ICANON|IEXTEN) == (ICANON|IEXTEN)) {
  896                         if (CMP_CC(VSTATUS, c)) {
  897                                 tty_signal_pgrp(tp, SIGINFO);
  898                                 return (0);
  899                         }
  900                 }
  901 
  902                 /*
  903                  * When compared to the old implementation, this
  904                  * implementation also flushes the output queue. POSIX
  905                  * is really brief about this, but does makes us assume
  906                  * we have to do so.
  907                  */
  908                 signal = 0;
  909                 if (CMP_CC(VINTR, c)) {
  910                         signal = SIGINT;
  911                 } else if (CMP_CC(VQUIT, c)) {
  912                         signal = SIGQUIT;
  913                 } else if (CMP_CC(VSUSP, c)) {
  914                         signal = SIGTSTP;
  915                 }
  916 
  917                 if (signal != 0) {
  918                         /*
  919                          * Echo the character before signalling the
  920                          * processes.
  921                          */
  922                         if (!CMP_FLAG(l, NOFLSH))
  923                                 tty_flush(tp, FREAD|FWRITE);
  924                         ttydisc_echo(tp, c, 0);
  925                         tty_signal_pgrp(tp, signal);
  926                         return (0);
  927                 }
  928         }
  929 
  930         /*
  931          * Handle start/stop characters.
  932          */
  933         if (CMP_FLAG(i, IXON)) {
  934                 if (CMP_CC(VSTOP, c)) {
  935                         /* Stop it if we aren't stopped yet. */
  936                         if ((tp->t_flags & TF_STOPPED) == 0) {
  937                                 tp->t_flags |= TF_STOPPED;
  938                                 return (0);
  939                         }
  940                         /*
  941                          * Fallthrough:
  942                          * When VSTART == VSTOP, we should make this key
  943                          * toggle it.
  944                          */
  945                         if (!CMP_CC(VSTART, c))
  946                                 return (0);
  947                 }
  948                 if (CMP_CC(VSTART, c)) {
  949                         tp->t_flags &= ~TF_STOPPED;
  950                         return (0);
  951                 }
  952         }
  953 
  954         /* Conversion of CR and NL. */
  955         switch (c) {
  956         case CCR:
  957                 if (CMP_FLAG(i, IGNCR))
  958                         return (0);
  959                 if (CMP_FLAG(i, ICRNL))
  960                         c = CNL;
  961                 break;
  962         case CNL:
  963                 if (CMP_FLAG(i, INLCR))
  964                         c = CCR;
  965                 break;
  966         }
  967 
  968         /* Canonical line editing. */
  969         if (CMP_FLAG(l, ICANON)) {
  970                 if (CMP_CC(VERASE, c) || CMP_CC(VERASE2, c)) {
  971                         ttydisc_rubchar(tp);
  972                         return (0);
  973                 } else if (CMP_CC(VKILL, c)) {
  974                         while (ttydisc_rubchar(tp) == 0);
  975                         return (0);
  976                 } else if (CMP_FLAG(l, IEXTEN)) {
  977                         if (CMP_CC(VWERASE, c)) {
  978                                 ttydisc_rubword(tp);
  979                                 return (0);
  980                         } else if (CMP_CC(VREPRINT, c)) {
  981                                 ttydisc_reprint(tp);
  982                                 return (0);
  983                         }
  984                 }
  985         }
  986 
  987 processed:
  988         if (CMP_FLAG(i, PARMRK) && (unsigned char)c == 0xff) {
  989                 /* Print 0xff 0xff. */
  990                 ob[1] = 0xff;
  991                 ol = 2;
  992                 quote = 1;
  993         } else {
  994                 ob[0] = c;
  995                 ol = 1;
  996         }
  997 
  998         goto print;
  999 
 1000 parmrk:
 1001         if (CMP_FLAG(i, PARMRK)) {
 1002                 /* Prepend 0xff 0x00 0x.. */
 1003                 ob[2] = c;
 1004                 ol = 3;
 1005                 quote = 1;
 1006         } else {
 1007                 ob[0] = c;
 1008                 ol = 1;
 1009         }
 1010 
 1011 print:
 1012         /* See if we can store this on the input queue. */
 1013         if (ttyinq_write_nofrag(&tp->t_inq, ob, ol, quote) != 0) {
 1014                 if (CMP_FLAG(i, IMAXBEL))
 1015                         ttyoutq_write_nofrag(&tp->t_outq, "\a", 1);
 1016 
 1017                 /*
 1018                  * Prevent a deadlock here. It may be possible that a
 1019                  * user has entered so much data, there is no data
 1020                  * available to read(), but the buffers are full anyway.
 1021                  *
 1022                  * Only enter the high watermark if the device driver
 1023                  * can actually transmit something.
 1024                  */
 1025                 if (ttyinq_bytescanonicalized(&tp->t_inq) == 0)
 1026                         return (0);
 1027 
 1028                 tty_hiwat_in_block(tp);
 1029                 return (-1);
 1030         }
 1031 
 1032         /*
 1033          * In raw mode, we canonicalize after receiving a single
 1034          * character. Otherwise, we canonicalize when we receive a
 1035          * newline, VEOL or VEOF, but only when it isn't quoted.
 1036          */
 1037         if (!CMP_FLAG(l, ICANON) ||
 1038             (!quote && (c == CNL || CMP_CC(VEOL, c) || CMP_CC(VEOF, c)))) {
 1039                 ttyinq_canonicalize(&tp->t_inq);
 1040         }
 1041 
 1042         ttydisc_echo(tp, c, quote);
 1043 
 1044         return (0);
 1045 }
 1046 
 1047 size_t
 1048 ttydisc_rint_bypass(struct tty *tp, const void *buf, size_t len)
 1049 {
 1050         size_t ret;
 1051 
 1052         tty_lock_assert(tp, MA_OWNED);
 1053         
 1054         MPASS(tp->t_flags & TF_BYPASS);
 1055 
 1056         atomic_add_long(&tty_nin, len);
 1057 
 1058         if (ttyhook_hashook(tp, rint_bypass))
 1059                 return ttyhook_rint_bypass(tp, buf, len);
 1060 
 1061         ret = ttyinq_write(&tp->t_inq, buf, len, 0);
 1062         ttyinq_canonicalize(&tp->t_inq);
 1063         if (ret < len)
 1064                 tty_hiwat_in_block(tp);
 1065 
 1066         return (ret);
 1067 }
 1068 
 1069 void
 1070 ttydisc_rint_done(struct tty *tp)
 1071 {
 1072 
 1073         tty_lock_assert(tp, MA_OWNED);
 1074 
 1075         if (ttyhook_hashook(tp, rint_done))
 1076                 ttyhook_rint_done(tp);
 1077 
 1078         /* Wake up readers. */
 1079         tty_wakeup(tp, FREAD);
 1080         /* Wake up driver for echo. */
 1081         ttydevsw_outwakeup(tp);
 1082 }
 1083 
 1084 size_t
 1085 ttydisc_rint_poll(struct tty *tp)
 1086 {
 1087         size_t l;
 1088 
 1089         tty_lock_assert(tp, MA_OWNED);
 1090 
 1091         if (ttyhook_hashook(tp, rint_poll))
 1092                 return ttyhook_rint_poll(tp);
 1093 
 1094         /*
 1095          * XXX: Still allow character input when there's no space in the
 1096          * buffers, but we haven't entered the high watermark. This is
 1097          * to allow backspace characters to be inserted when in
 1098          * canonical mode.
 1099          */
 1100         l = ttyinq_bytesleft(&tp->t_inq);
 1101         if (l == 0 && (tp->t_flags & TF_HIWAT_IN) == 0)
 1102                 return (1);
 1103         
 1104         return (l);
 1105 }
 1106 
 1107 static void
 1108 ttydisc_wakeup_watermark(struct tty *tp)
 1109 {
 1110         size_t c;
 1111 
 1112         c = ttyoutq_bytesleft(&tp->t_outq);
 1113         if (tp->t_flags & TF_HIWAT_OUT) {
 1114                 /* Only allow us to run when we're below the watermark. */
 1115                 if (c < tp->t_outlow)
 1116                         return;
 1117 
 1118                 /* Reset the watermark. */
 1119                 tp->t_flags &= ~TF_HIWAT_OUT;
 1120         } else {
 1121                 /* Only run when we have data at all. */
 1122                 if (c == 0)
 1123                         return;
 1124         }
 1125         tty_wakeup(tp, FWRITE);
 1126 }
 1127 
 1128 size_t
 1129 ttydisc_getc(struct tty *tp, void *buf, size_t len)
 1130 {
 1131 
 1132         tty_lock_assert(tp, MA_OWNED);
 1133 
 1134         if (tp->t_flags & TF_STOPPED)
 1135                 return (0);
 1136 
 1137         if (ttyhook_hashook(tp, getc_inject))
 1138                 return ttyhook_getc_inject(tp, buf, len);
 1139 
 1140         len = ttyoutq_read(&tp->t_outq, buf, len);
 1141 
 1142         if (ttyhook_hashook(tp, getc_capture))
 1143                 ttyhook_getc_capture(tp, buf, len);
 1144 
 1145         ttydisc_wakeup_watermark(tp);
 1146         atomic_add_long(&tty_nout, len);
 1147 
 1148         return (len);
 1149 }
 1150 
 1151 int
 1152 ttydisc_getc_uio(struct tty *tp, struct uio *uio)
 1153 {
 1154         int error = 0;
 1155         int obytes = uio->uio_resid;
 1156         size_t len;
 1157         char buf[TTY_STACKBUF];
 1158 
 1159         tty_lock_assert(tp, MA_OWNED);
 1160 
 1161         if (tp->t_flags & TF_STOPPED)
 1162                 return (0);
 1163 
 1164         /*
 1165          * When a TTY hook is attached, we cannot perform unbuffered
 1166          * copying to userspace. Just call ttydisc_getc() and
 1167          * temporarily store data in a shadow buffer.
 1168          */
 1169         if (ttyhook_hashook(tp, getc_capture) ||
 1170             ttyhook_hashook(tp, getc_inject)) {
 1171                 while (uio->uio_resid > 0) {
 1172                         /* Read to shadow buffer. */
 1173                         len = ttydisc_getc(tp, buf,
 1174                             MIN(uio->uio_resid, sizeof buf));
 1175                         if (len == 0)
 1176                                 break;
 1177 
 1178                         /* Copy to userspace. */
 1179                         tty_unlock(tp);
 1180                         error = uiomove(buf, len, uio);
 1181                         tty_lock(tp);
 1182                         
 1183                         if (error != 0)
 1184                                 break;
 1185                 }
 1186         } else {
 1187                 error = ttyoutq_read_uio(&tp->t_outq, tp, uio);
 1188 
 1189                 ttydisc_wakeup_watermark(tp);
 1190                 atomic_add_long(&tty_nout, obytes - uio->uio_resid);
 1191         }
 1192 
 1193         return (error);
 1194 }
 1195 
 1196 size_t
 1197 ttydisc_getc_poll(struct tty *tp)
 1198 {
 1199 
 1200         tty_lock_assert(tp, MA_OWNED);
 1201 
 1202         if (tp->t_flags & TF_STOPPED)
 1203                 return (0);
 1204 
 1205         if (ttyhook_hashook(tp, getc_poll))
 1206                 return ttyhook_getc_poll(tp);
 1207 
 1208         return ttyoutq_bytesused(&tp->t_outq);
 1209 }
 1210 
 1211 /*
 1212  * XXX: not really related to the TTYDISC, but we'd better put
 1213  * tty_putchar() here, because we need to perform proper output
 1214  * processing.
 1215  */
 1216 
 1217 int
 1218 tty_putchar(struct tty *tp, char c)
 1219 {
 1220         tty_lock_assert(tp, MA_OWNED);
 1221 
 1222         if (tty_gone(tp))
 1223                 return (-1);
 1224 
 1225         ttydisc_echo_force(tp, c, 0);
 1226         tp->t_writepos = tp->t_column;
 1227         ttyinq_reprintpos_set(&tp->t_inq);
 1228 
 1229         ttydevsw_outwakeup(tp);
 1230         return (0);
 1231 }

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