allow select on exceptional to check control operations

[unix-history] / usr / src / sys / kern / tty_pty.c

/*
* Copyright (c) 1982 Regents of the University of California.
* All rights reserved.  The Berkeley software License Agreement
* specifies the terms and conditions for redistribution.
*
*      @(#)tty_pty.c   6.16 (Berkeley) %G%
*/

/*
* Pseudo-teletype Driver
* (Actually two drivers, requiring two entries in 'cdevsw')
*/
#include "pty.h"

#if NPTY > 0
#include "param.h"
#include "systm.h"
#include "ioctl.h"
#include "tty.h"
#include "dir.h"
#include "user.h"
#include "conf.h"
#include "file.h"
#include "proc.h"
#include "uio.h"
#include "kernel.h"

#if NPTY == 1
#undef NPTY
#define NPTY    32              /* crude XXX */
#endif

#define BUFSIZ 100              /* Chunk size iomoved to/from user */

/*
* pts == /dev/tty[pqrs]?
* ptc == /dev/pty[pqrs]?
*/
struct  tty pt_tty[NPTY];
struct  pt_ioctl {
       int     pt_flags;
       int     pt_gensym;
       struct  proc *pt_selr, *pt_selw;
       u_char  pt_send;
       u_char  pt_ucntl;
} pt_ioctl[NPTY];
int     npty = NPTY;            /* for pstat -t */

#define PF_RCOLL        0x01
#define PF_WCOLL        0x02
#define PF_NBIO         0x04
#define PF_PKT          0x08            /* packet mode */
#define PF_STOPPED      0x10            /* user told stopped */
#define PF_REMOTE       0x20            /* remote and flow controlled input */
#define PF_NOSTOP       0x40
#define PF_UCNTL        0x80            /* user control mode */

/*ARGSUSED*/
ptsopen(dev, flag)
       dev_t dev;
{
       register struct tty *tp;
       int error;

#ifdef lint
       npty = npty;
#endif
       if (minor(dev) >= NPTY)
               return (ENXIO);
       tp = &pt_tty[minor(dev)];
       if ((tp->t_state & TS_ISOPEN) == 0) {
               ttychars(tp);           /* Set up default chars */
               tp->t_ispeed = tp->t_ospeed = EXTB;
               tp->t_flags = 0;        /* No features (nor raw mode) */
       } else if (tp->t_state&TS_XCLUDE && u.u_uid != 0)
               return (EBUSY);
       if (tp->t_oproc)                        /* Ctrlr still around. */
               tp->t_state |= TS_CARR_ON;
       while ((tp->t_state & TS_CARR_ON) == 0) {
               tp->t_state |= TS_WOPEN;
               sleep((caddr_t)&tp->t_rawq, TTIPRI);
       }
       error = (*linesw[tp->t_line].l_open)(dev, tp);
       ptcwakeup(tp, FREAD|FWRITE);
       return (error);
}

ptsclose(dev)
       dev_t dev;
{
       register struct tty *tp;

       tp = &pt_tty[minor(dev)];
       (*linesw[tp->t_line].l_close)(tp);
       ttyclose(tp);
       ptcwakeup(tp, FREAD|FWRITE);
}

ptsread(dev, uio)
       dev_t dev;
       struct uio *uio;
{
       register struct tty *tp = &pt_tty[minor(dev)];
       register struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
       int error = 0;

again:
       if (pti->pt_flags & PF_REMOTE) {
               while (tp == u.u_ttyp && u.u_procp->p_pgrp != tp->t_pgrp) {
                       if ((u.u_procp->p_sigignore & sigmask(SIGTTIN)) ||
                           (u.u_procp->p_sigmask & sigmask(SIGTTIN)) ||
                           u.u_procp->p_flag&SVFORK)
                               return (EIO);
                       gsignal(u.u_procp->p_pgrp, SIGTTIN);
                       sleep((caddr_t)&lbolt, TTIPRI);
               }
               if (tp->t_canq.c_cc == 0) {
                       if (tp->t_state & TS_NBIO)
                               return (EWOULDBLOCK);
                       sleep((caddr_t)&tp->t_canq, TTIPRI);
                       goto again;
               }
               while (tp->t_canq.c_cc > 1 && uio->uio_resid > 0)
                       if (ureadc(getc(&tp->t_canq), uio) < 0) {
                               error = EFAULT;
                               break;
                       }
               if (tp->t_canq.c_cc == 1)
                       (void) getc(&tp->t_canq);
               if (tp->t_canq.c_cc)
                       return (error);
       } else
               if (tp->t_oproc)
                       error = (*linesw[tp->t_line].l_read)(tp, uio);
       ptcwakeup(tp, FWRITE);
       return (error);
}

/*
* Write to pseudo-tty.
* Wakeups of controlling tty will happen
* indirectly, when tty driver calls ptsstart.
*/
ptswrite(dev, uio)
       dev_t dev;
       struct uio *uio;
{
       register struct tty *tp;

       tp = &pt_tty[minor(dev)];
       if (tp->t_oproc == 0)
               return (EIO);
       return ((*linesw[tp->t_line].l_write)(tp, uio));
}

/*
* Start output on pseudo-tty.
* Wake up process selecting or sleeping for input from controlling tty.
*/
ptsstart(tp)
       struct tty *tp;
{
       register struct pt_ioctl *pti = &pt_ioctl[minor(tp->t_dev)];

       if (tp->t_state & TS_TTSTOP)
               return;
       if (pti->pt_flags & PF_STOPPED) {
               pti->pt_flags &= ~PF_STOPPED;
               pti->pt_send = TIOCPKT_START;
       }
       ptcwakeup(tp, FREAD);
}

ptcwakeup(tp, flag)
       struct tty *tp;
{
       struct pt_ioctl *pti = &pt_ioctl[minor(tp->t_dev)];

       if (flag & FREAD) {
               if (pti->pt_selr) {
                       selwakeup(pti->pt_selr, pti->pt_flags & PF_RCOLL);
                       pti->pt_selr = 0;
                       pti->pt_flags &= ~PF_RCOLL;
               }
               wakeup((caddr_t)&tp->t_outq.c_cf);
       }
       if (flag & FWRITE) {
               if (pti->pt_selw) {
                       selwakeup(pti->pt_selw, pti->pt_flags & PF_WCOLL);
                       pti->pt_selw = 0;
                       pti->pt_flags &= ~PF_WCOLL;
               }
               wakeup((caddr_t)&tp->t_rawq.c_cf);
       }
}

/*ARGSUSED*/
ptcopen(dev, flag)
       dev_t dev;
       int flag;
{
       register struct tty *tp;
       struct pt_ioctl *pti;

       if (minor(dev) >= NPTY)
               return (ENXIO);
       tp = &pt_tty[minor(dev)];
       if (tp->t_oproc)
               return (EIO);
       tp->t_oproc = ptsstart;
       (void)(*linesw[tp->t_line].l_modem)(tp, 1);
       tp->t_state |= TS_CARR_ON;
       pti = &pt_ioctl[minor(dev)];
       pti->pt_flags = 0;
       pti->pt_send = 0;
       pti->pt_ucntl = 0;
       return (0);
}

ptcclose(dev)
       dev_t dev;
{
       register struct tty *tp;

       tp = &pt_tty[minor(dev)];
       (void)(*linesw[tp->t_line].l_modem)(tp, 0);
       tp->t_oproc = 0;                /* mark closed */
}

ptcread(dev, uio)
       dev_t dev;
       struct uio *uio;
{
       register struct tty *tp = &pt_tty[minor(dev)];
       struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
       char buf[BUFSIZ];
       int error = 0, cc;

       /*
        * We want to block until the slave
        * is open, and there's something to read;
        * but if we lost the slave or we're NBIO,
        * then return the appropriate error instead.
        */
       for (;;) {
               if (tp->t_state&TS_ISOPEN) {
                       if (pti->pt_flags&PF_PKT && pti->pt_send) {
                               error = ureadc(pti->pt_send, uio);
                               if (error)
                                       return (error);
                               pti->pt_send = 0;
                               return (0);
                       }
                       if (pti->pt_flags&PF_UCNTL && pti->pt_ucntl) {
                               error = ureadc(pti->pt_ucntl, uio);
                               if (error)
                                       return (error);
                               pti->pt_ucntl = 0;
                               return (0);
                       }
                       if (tp->t_outq.c_cc && (tp->t_state&TS_TTSTOP) == 0)
                               break;
               }
               if ((tp->t_state&TS_CARR_ON) == 0)
                       return (EIO);
               if (pti->pt_flags&PF_NBIO)
                       return (EWOULDBLOCK);
               sleep((caddr_t)&tp->t_outq.c_cf, TTIPRI);
       }
       if (pti->pt_flags & (PF_PKT|PF_UCNTL))
               error = ureadc(0, uio);
       while (uio->uio_resid > 0 && error == 0) {
               cc = q_to_b(&tp->t_outq, buf, MIN(uio->uio_resid, BUFSIZ));
               if (cc <= 0)
                       break;
               error = uiomove(buf, cc, UIO_READ, uio);
       }
       if (tp->t_outq.c_cc <= TTLOWAT(tp)) {
               if (tp->t_state&TS_ASLEEP) {
                       tp->t_state &= ~TS_ASLEEP;
                       wakeup((caddr_t)&tp->t_outq);
               }
               if (tp->t_wsel) {
                       selwakeup(tp->t_wsel, tp->t_state & TS_WCOLL);
                       tp->t_wsel = 0;
                       tp->t_state &= ~TS_WCOLL;
               }
       }
       return (error);
}

ptsstop(tp, flush)
       register struct tty *tp;
       int flush;
{
       struct pt_ioctl *pti = &pt_ioctl[minor(tp->t_dev)];
       int flag;

       /* note: FLUSHREAD and FLUSHWRITE already ok */
       if (flush == 0) {
               flush = TIOCPKT_STOP;
               pti->pt_flags |= PF_STOPPED;
       } else
               pti->pt_flags &= ~PF_STOPPED;
       pti->pt_send |= flush;
       /* change of perspective */
       flag = 0;
       if (flush & FREAD)
               flag |= FWRITE;
       if (flush & FWRITE)
               flag |= FREAD;
       ptcwakeup(tp, flag);
}

ptcselect(dev, rw)
       dev_t dev;
       int rw;
{
       register struct tty *tp = &pt_tty[minor(dev)];
       struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
       struct proc *p;
       int s;

       if ((tp->t_state&TS_CARR_ON) == 0)
               return (1);
       s = spl5();
       switch (rw) {

       case FREAD:
               if ((tp->t_state&TS_ISOPEN) &&
                    tp->t_outq.c_cc && (tp->t_state&TS_TTSTOP) == 0) {
                       splx(s);
                       return (1);
               }
               /* FALLTHROUGH */

       case 0:                                 /* exceptional */
               if ((tp->t_state&TS_ISOPEN) &&
                   (pti->pt_flags&PF_PKT && pti->pt_send ||
                    pti->pt_flags&PF_UCNTL && pti->pt_ucntl)) {
                       splx(s);
                       return (1);
               }
               if ((p = pti->pt_selr) && p->p_wchan == (caddr_t)&selwait)
                       pti->pt_flags |= PF_RCOLL;
               else
                       pti->pt_selr = u.u_procp;
               break;


       case FWRITE:
               if ((tp->t_state&TS_ISOPEN) &&
                   ((pti->pt_flags&PF_REMOTE) == 0 || tp->t_canq.c_cc == 0)) {
                       splx(s);
                       return (1);
               }
               if ((p = pti->pt_selw) && p->p_wchan == (caddr_t)&selwait)
                       pti->pt_flags |= PF_WCOLL;
               else
                       pti->pt_selw = u.u_procp;
               break;

       }
       splx(s);
       return (0);
}

ptcwrite(dev, uio)
       dev_t dev;
       register struct uio *uio;
{
       register struct tty *tp = &pt_tty[minor(dev)];
       register struct iovec *iov;
       register char *cp;
       register int cc = 0;
       char locbuf[BUFSIZ];
       int cnt = 0;
       struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
       int error = 0;

again:
       if ((tp->t_state&TS_ISOPEN) == 0)
               goto block;
       if (pti->pt_flags & PF_REMOTE) {
               if (tp->t_canq.c_cc)
                       goto block;
               while (uio->uio_iovcnt > 0 && tp->t_canq.c_cc < TTYHOG - 1) {
                       iov = uio->uio_iov;
                       if (iov->iov_len == 0) {
                               uio->uio_iovcnt--;      
                               uio->uio_iov++;
                               continue;
                       }
                       if (cc == 0) {
                               cc = MIN(iov->iov_len, BUFSIZ);
                               cc = MIN(cc, TTYHOG - 1 - tp->t_canq.c_cc);
                               cp = locbuf;
                               error = uiomove(cp, cc, UIO_WRITE, uio);
                               if (error)
                                       return (error);
                               /* check again for safety */
                               if ((tp->t_state&TS_ISOPEN) == 0)
                                       return (EIO);
                       }
                       if (cc)
                               (void) b_to_q(cp, cc, &tp->t_canq);
                       cc = 0;
               }
               (void) putc(0, &tp->t_canq);
               ttwakeup(tp);
               wakeup((caddr_t)&tp->t_canq);
               return (0);
       }
       while (uio->uio_iovcnt > 0) {
               iov = uio->uio_iov;
               if (cc == 0) {
                       if (iov->iov_len == 0) {
                               uio->uio_iovcnt--;      
                               uio->uio_iov++;
                               continue;
                       }
                       cc = MIN(iov->iov_len, BUFSIZ);
                       cp = locbuf;
                       error = uiomove(cp, cc, UIO_WRITE, uio);
                       if (error)
                               return (error);
                       /* check again for safety */
                       if ((tp->t_state&TS_ISOPEN) == 0)
                               return (EIO);
               }
               while (cc > 0) {
                       if ((tp->t_rawq.c_cc + tp->t_canq.c_cc) >= TTYHOG - 2 &&
                           (tp->t_canq.c_cc > 0)) {
                               wakeup((caddr_t)&tp->t_rawq);
                               goto block;
                       }
                       (*linesw[tp->t_line].l_rint)(*cp++, tp);
                       cnt++;
                       cc--;
               }
               cc = 0;
       }
       return (0);
block:
       /*
        * Come here to wait for slave to open, for space
        * in outq, or space in rawq.
        */
       if ((tp->t_state&TS_CARR_ON) == 0)
               return (EIO);
       if (pti->pt_flags & PF_NBIO) {
               iov->iov_base -= cc;
               iov->iov_len += cc;
               uio->uio_resid += cc;
               uio->uio_offset -= cc;
               if (cnt == 0)
                       return (EWOULDBLOCK);
               return (0);
       }
       sleep((caddr_t)&tp->t_rawq.c_cf, TTOPRI);
       goto again;
}

/*ARGSUSED*/
ptyioctl(dev, cmd, data, flag)
       caddr_t data;
       dev_t dev;
{
       register struct tty *tp = &pt_tty[minor(dev)];
       register struct pt_ioctl *pti = &pt_ioctl[minor(dev)];
       int stop, error;
       extern ttyinput();

       /*
        * IF CONTROLLER STTY THEN MUST FLUSH TO PREVENT A HANG.
        * ttywflush(tp) will hang if there are characters in the outq.
        */
       if (cdevsw[major(dev)].d_open == ptcopen)
               switch (cmd) {

               case TIOCPKT:
                       if (*(int *)data) {
                               if (pti->pt_flags & PF_UCNTL)
                                       return (EINVAL);
                               pti->pt_flags |= PF_PKT;
                       } else
                               pti->pt_flags &= ~PF_PKT;
                       return (0);

               case TIOCUCNTL:
                       if (*(int *)data) {
                               if (pti->pt_flags & PF_PKT)
                                       return (EINVAL);
                               pti->pt_flags |= PF_UCNTL;
                       } else
                               pti->pt_flags &= ~PF_UCNTL;
                       return (0);

               case TIOCREMOTE:
                       if (*(int *)data)
                               pti->pt_flags |= PF_REMOTE;
                       else
                               pti->pt_flags &= ~PF_REMOTE;
                       ttyflush(tp, FREAD|FWRITE);
                       return (0);

               case FIONBIO:
                       if (*(int *)data)
                               pti->pt_flags |= PF_NBIO;
                       else
                               pti->pt_flags &= ~PF_NBIO;
                       return (0);

               case TIOCSETP:
               case TIOCSETN:
               case TIOCSETD:
                       while (getc(&tp->t_outq) >= 0)
                               ;
                       break;
               }
       error = ttioctl(tp, cmd, data, flag);
       /*
        * Since we use the tty queues internally,
        * pty's can't be switched to disciplines which overwrite
        * the queues.  We can't tell anything about the discipline
        * from here...
        */
       if (linesw[tp->t_line].l_rint != ttyinput) {
               (*linesw[tp->t_line].l_close)(tp);
               tp->t_line = 0;
               (void)(*linesw[tp->t_line].l_open)(dev, tp);
               error = ENOTTY;
       }
       if (error < 0) {
               if (pti->pt_flags & PF_UCNTL &&
                   (cmd & ~0xff) == _IO(u,0)) {
                       if (cmd & 0xff) {
                               pti->pt_ucntl = (u_char)cmd;
                               ptcwakeup(tp, FREAD);
                       }
                       return (0);
               }
               error = ENOTTY;
       }
       stop = (tp->t_flags & RAW) == 0 &&
           tp->t_stopc == CTRL(s) && tp->t_startc == CTRL(q);
       if (pti->pt_flags & PF_NOSTOP) {
               if (stop) {
                       pti->pt_send &= TIOCPKT_NOSTOP;
                       pti->pt_send |= TIOCPKT_DOSTOP;
                       pti->pt_flags &= ~PF_NOSTOP;
                       ptcwakeup(tp, FREAD);
               }
       } else {
               if (!stop) {
                       pti->pt_send &= ~TIOCPKT_DOSTOP;
                       pti->pt_send |= TIOCPKT_NOSTOP;
                       pti->pt_flags |= PF_NOSTOP;
                       ptcwakeup(tp, FREAD);
               }
       }
       return (error);
}
#endif