minix/drivers/tty/pty.c

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/* pty.c - pseudo terminal driver Author: Kees J. Bot
* 30 Dec 1995
* PTYs can be seen as a bidirectional pipe with TTY
* input and output processing. For example a simple rlogin session:
*
* keyboard -> rlogin -> in.rld -> /dev/ptypX -> /dev/ttypX -> shell
* shell -> /dev/ttypX -> /dev/ptypX -> in.rld -> rlogin -> screen
*
* This file takes care of copying data between the tty/pty device pairs and
* the open/read/write/close calls on the pty devices. The TTY task takes
* care of the input and output processing (interrupt, backspace, raw I/O,
* etc.) using the pty_read() and pty_write() functions as the "keyboard" and
* "screen" functions of the ttypX devices.
* Be careful when reading this code, the terms "reading" and "writing" are
* used both for the tty and the pty end of the pseudo tty. Writes to one
* end are to be read at the other end and vice-versa.
*/
#include "../drivers.h"
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#include <assert.h>
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#include <termios.h>
#include <signal.h>
#include <minix/com.h>
#include <minix/callnr.h>
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#include <sys/select.h>
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#include "tty.h"
#if NR_PTYS > 0
/* PTY bookkeeping structure, one per pty/tty pair. */
typedef struct pty {
tty_t *tty; /* associated TTY structure */
char state; /* flags: busy, closed, ... */
/* Read call on /dev/ptypX. */
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char rdsendreply; /* send a reply (instead of notify) */
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char rdcaller; /* process making the call (usually FS) */
char rdproc; /* process that wants to read from the pty */
vir_bytes rdvir; /* virtual address in readers address space */
int rdleft; /* # bytes yet to be read */
int rdcum; /* # bytes written so far */
/* Write call to /dev/ptypX. */
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char wrsendreply; /* send a reply (instead of notify) */
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char wrcaller; /* process making the call (usually FS) */
char wrproc; /* process that wants to write to the pty */
vir_bytes wrvir; /* virtual address in writers address space */
int wrleft; /* # bytes yet to be written */
int wrcum; /* # bytes written so far */
/* Output buffer. */
int ocount; /* # characters in the buffer */
char *ohead, *otail; /* head and tail of the circular buffer */
char obuf[128]; /* buffer for bytes going to the pty reader */
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/* select() data. */
int select_ops, /* Which operations do we want to know about? */
select_proc, /* Who wants to know about it? */
select_ready_ops; /* For callback. */
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} pty_t;
#define PTY_ACTIVE 0x01 /* pty is open/active */
#define TTY_CLOSED 0x02 /* tty side has closed down */
#define PTY_CLOSED 0x04 /* pty side has closed down */
PRIVATE pty_t pty_table[NR_PTYS]; /* PTY bookkeeping */
FORWARD _PROTOTYPE( int pty_write, (tty_t *tp, int try) );
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FORWARD _PROTOTYPE( void pty_echo, (tty_t *tp, int c) );
FORWARD _PROTOTYPE( void pty_start, (pty_t *pp) );
FORWARD _PROTOTYPE( void pty_finish, (pty_t *pp) );
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FORWARD _PROTOTYPE( int pty_read, (tty_t *tp, int try) );
FORWARD _PROTOTYPE( int pty_close, (tty_t *tp, int try) );
FORWARD _PROTOTYPE( int pty_icancel, (tty_t *tp, int try) );
FORWARD _PROTOTYPE( int pty_ocancel, (tty_t *tp, int try) );
FORWARD _PROTOTYPE( int pty_select, (tty_t *tp, message *m) );
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/*==========================================================================*
* do_pty *
*==========================================================================*/
PUBLIC void do_pty(tp, m_ptr)
tty_t *tp;
message *m_ptr;
{
/* Perform an open/close/read/write call on a /dev/ptypX device. */
pty_t *pp = tp->tty_priv;
int r;
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phys_bytes p;
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switch (m_ptr->m_type) {
case DEV_READ:
/* Check, store information on the reader, do I/O. */
if (pp->state & TTY_CLOSED) {
r = 0;
break;
}
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if (pp->rdleft != 0 || pp->rdcum != 0) {
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r = EIO;
break;
}
if (m_ptr->COUNT <= 0) {
r = EINVAL;
break;
}
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#if DEAD_CODE
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if (numap_local(m_ptr->PROC_NR, (vir_bytes) m_ptr->ADDRESS,
m_ptr->COUNT) == 0) {
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#else
if ((r = sys_umap(m_ptr->PROC_NR, D, (vir_bytes) m_ptr->ADDRESS,
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m_ptr->COUNT, &p)) != OK) {
#endif
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break;
}
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pp->rdsendreply = TRUE;
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pp->rdcaller = m_ptr->m_source;
pp->rdproc = m_ptr->PROC_NR;
pp->rdvir = (vir_bytes) m_ptr->ADDRESS;
pp->rdleft = m_ptr->COUNT;
pty_start(pp);
handle_events(tp);
if (pp->rdleft == 0) return; /* already done */
if (m_ptr->TTY_FLAGS & O_NONBLOCK) {
r = EAGAIN; /* don't suspend */
pp->rdleft = pp->rdcum = 0;
} else {
r = SUSPEND; /* do suspend */
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pp->rdsendreply = FALSE;
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}
break;
case DEV_WRITE:
/* Check, store information on the writer, do I/O. */
if (pp->state & TTY_CLOSED) {
r = EIO;
break;
}
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if (pp->wrleft != 0 || pp->wrcum != 0) {
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r = EIO;
break;
}
if (m_ptr->COUNT <= 0) {
r = EINVAL;
break;
}
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#if DEAD_CODE
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if (numap_local(m_ptr->PROC_NR, (vir_bytes) m_ptr->ADDRESS,
m_ptr->COUNT) == 0) {
r = EFAULT;
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#else
if ((r = sys_umap(m_ptr->PROC_NR, D, (vir_bytes) m_ptr->ADDRESS,
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m_ptr->COUNT, &p)) != OK) {
#endif
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break;
}
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pp->wrsendreply = TRUE;
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pp->wrcaller = m_ptr->m_source;
pp->wrproc = m_ptr->PROC_NR;
pp->wrvir = (vir_bytes) m_ptr->ADDRESS;
pp->wrleft = m_ptr->COUNT;
handle_events(tp);
if (pp->wrleft == 0) return; /* already done */
if (m_ptr->TTY_FLAGS & O_NONBLOCK) { /* don't suspend */
r = pp->wrcum > 0 ? pp->wrcum : EAGAIN;
pp->wrleft = pp->wrcum = 0;
} else {
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pp->wrsendreply = FALSE; /* do suspend */
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r = SUSPEND;
}
break;
case DEV_OPEN:
r = pp->state != 0 ? EIO : OK;
pp->state |= PTY_ACTIVE;
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pp->rdcum = 0;
pp->wrcum = 0;
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break;
case DEV_CLOSE:
r = OK;
if (pp->state & TTY_CLOSED) {
pp->state = 0;
} else {
pp->state |= PTY_CLOSED;
sigchar(tp, SIGHUP);
}
break;
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case DEV_SELECT:
r = pty_select(tp, m_ptr);
break;
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case CANCEL:
if (m_ptr->PROC_NR == pp->rdproc) {
/* Cancel a read from a PTY. */
pp->rdleft = pp->rdcum = 0;
}
if (m_ptr->PROC_NR == pp->wrproc) {
/* Cancel a write to a PTY. */
pp->wrleft = pp->wrcum = 0;
}
r = EINTR;
break;
default:
r = EINVAL;
}
tty_reply(TASK_REPLY, m_ptr->m_source, m_ptr->PROC_NR, r);
}
/*==========================================================================*
* pty_write *
*==========================================================================*/
PRIVATE int pty_write(tp, try)
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tty_t *tp;
int try;
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{
/* (*dev_write)() routine for PTYs. Transfer bytes from the writer on
* /dev/ttypX to the output buffer.
*/
pty_t *pp = tp->tty_priv;
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int count, ocount, s;
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phys_bytes user_phys;
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/* PTY closed down? */
if (pp->state & PTY_CLOSED) {
if(try) return 1;
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if (tp->tty_outleft > 0) {
tty_reply(tp->tty_outrepcode, tp->tty_outcaller,
tp->tty_outproc, EIO);
tp->tty_outleft = tp->tty_outcum = 0;
}
return;
}
/* While there is something to do. */
for (;;) {
ocount = buflen(pp->obuf) - pp->ocount;
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if(try) return (ocount > 0);
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count = bufend(pp->obuf) - pp->ohead;
if (count > ocount) count = ocount;
if (count > tp->tty_outleft) count = tp->tty_outleft;
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if (count == 0 || tp->tty_inhibited)
break;
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/* Copy from user space to the PTY output buffer. */
if((s = sys_vircopy(tp->tty_outproc, D, (vir_bytes) tp->tty_out_vir,
SELF, D, (vir_bytes) pp->ohead, (phys_bytes) count)) != OK) {
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printf("pty tty%d: copy failed (error %d)\n", s);
break;
}
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/* Perform output processing on the output buffer. */
out_process(tp, pp->obuf, pp->ohead, bufend(pp->obuf), &count, &ocount);
if (count == 0) break;
/* Assume echoing messed up by output. */
tp->tty_reprint = TRUE;
/* Bookkeeping. */
pp->ocount += ocount;
if ((pp->ohead += ocount) >= bufend(pp->obuf))
pp->ohead -= buflen(pp->obuf);
pty_start(pp);
tp->tty_out_vir += count;
tp->tty_outcum += count;
if ((tp->tty_outleft -= count) == 0) {
/* Output is finished, reply to the writer. */
tty_reply(tp->tty_outrepcode, tp->tty_outcaller,
tp->tty_outproc, tp->tty_outcum);
tp->tty_outcum = 0;
}
}
pty_finish(pp);
return 1;
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}
/*==========================================================================*
* pty_echo *
*==========================================================================*/
PRIVATE void pty_echo(tp, c)
tty_t *tp;
int c;
{
/* Echo one character. (Like pty_write, but only one character, optionally.) */
pty_t *pp = tp->tty_priv;
int count, ocount;
ocount = buflen(pp->obuf) - pp->ocount;
if (ocount == 0) return; /* output buffer full */
count = 1;
*pp->ohead = c; /* add one character */
out_process(tp, pp->obuf, pp->ohead, bufend(pp->obuf), &count, &ocount);
if (count == 0) return;
pp->ocount += ocount;
if ((pp->ohead += ocount) >= bufend(pp->obuf)) pp->ohead -= buflen(pp->obuf);
pty_start(pp);
}
/*==========================================================================*
* pty_start *
*==========================================================================*/
PRIVATE void pty_start(pp)
pty_t *pp;
{
/* Transfer bytes written to the output buffer to the PTY reader. */
int count;
/* While there are things to do. */
for (;;) {
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int s;
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count = bufend(pp->obuf) - pp->otail;
if (count > pp->ocount) count = pp->ocount;
if (count > pp->rdleft) count = pp->rdleft;
if (count == 0) break;
/* Copy from the output buffer to the readers address space. */
if((s = sys_vircopy(SELF, D, (vir_bytes)pp->otail,
(vir_bytes) pp->rdproc, D, (vir_bytes) pp->rdvir, (phys_bytes) count)) != OK) {
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printf("pty tty%d: copy failed (error %d)\n", s);
break;
}
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/* Bookkeeping. */
pp->ocount -= count;
if ((pp->otail += count) == bufend(pp->obuf)) pp->otail = pp->obuf;
pp->rdvir += count;
pp->rdcum += count;
pp->rdleft -= count;
}
}
/*==========================================================================*
* pty_finish *
*==========================================================================*/
PRIVATE void pty_finish(pp)
pty_t *pp;
{
/* Finish the read request of a PTY reader if there is at least one byte
* transferred.
*/
if (pp->rdcum > 0) {
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if (pp->rdsendreply) {
tty_reply(TASK_REPLY, pp->rdcaller, pp->rdproc, pp->rdcum);
pp->rdleft = pp->rdcum = 0;
}
else
notify(pp->rdcaller);
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}
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}
/*==========================================================================*
* pty_read *
*==========================================================================*/
PRIVATE int pty_read(tp, try)
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tty_t *tp;
int try;
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{
/* Offer bytes from the PTY writer for input on the TTY. (Do it one byte at
* a time, 99% of the writes will be for one byte, so no sense in being smart.)
*/
pty_t *pp = tp->tty_priv;
char c;
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if (pp->state & PTY_CLOSED) {
if(try) return 1;
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if (tp->tty_inleft > 0) {
tty_reply(tp->tty_inrepcode, tp->tty_incaller, tp->tty_inproc,
tp->tty_incum);
tp->tty_inleft = tp->tty_incum = 0;
}
return 1;
}
if(try) {
if(pp->wrleft > 0)
return 1;
return 0;
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}
while (pp->wrleft > 0) {
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int s;
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/* Transfer one character to 'c'. */
if((s = sys_vircopy(pp->wrproc, D, (vir_bytes) pp->wrvir,
SELF, D, (vir_bytes) &c, (phys_bytes) 1)) != OK) {
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printf("pty: copy failed (error %d)\n", s);
break;
}
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/* Input processing. */
if (in_process(tp, &c, 1) == 0) break;
/* PTY writer bookkeeping. */
pp->wrvir++;
pp->wrcum++;
if (--pp->wrleft == 0) {
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if (pp->wrsendreply) {
tty_reply(TASK_REPLY, pp->wrcaller, pp->wrproc,
pp->wrcum);
pp->wrcum = 0;
}
else
notify(pp->wrcaller);
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}
}
}
/*==========================================================================*
* pty_close *
*==========================================================================*/
PRIVATE int pty_close(tp, try)
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tty_t *tp;
int try;
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{
/* The tty side has closed, so shut down the pty side. */
pty_t *pp = tp->tty_priv;
if (!(pp->state & PTY_ACTIVE)) return;
if (pp->rdleft > 0) {
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assert(!pp->rdsendreply);
notify(pp->rdcaller);
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}
if (pp->wrleft > 0) {
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assert(!pp->wrsendreply);
notify(pp->wrcaller);
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}
if (pp->state & PTY_CLOSED) pp->state = 0; else pp->state |= TTY_CLOSED;
}
/*==========================================================================*
* pty_icancel *
*==========================================================================*/
PRIVATE int pty_icancel(tp, try)
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tty_t *tp;
int try;
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{
/* Discard waiting input. */
pty_t *pp = tp->tty_priv;
if (pp->wrleft > 0) {
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assert(!pp->wrsendreply);
pp->wrcum += pp->wrleft;
pp->wrleft= 0;
notify(pp->wrcaller);
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}
}
/*==========================================================================*
* pty_ocancel *
*==========================================================================*/
PRIVATE int pty_ocancel(tp, try)
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tty_t *tp;
int try;
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{
/* Drain the output buffer. */
pty_t *pp = tp->tty_priv;
pp->ocount = 0;
pp->otail = pp->ohead;
}
/*==========================================================================*
* pty_init *
*==========================================================================*/
PUBLIC void pty_init(tp)
tty_t *tp;
{
pty_t *pp;
int line;
/* Associate PTY and TTY structures. */
line = tp - &tty_table[NR_CONS + NR_RS_LINES];
pp = tp->tty_priv = &pty_table[line];
pp->tty = tp;
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pp->select_ops = 0;
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/* Set up output queue. */
pp->ohead = pp->otail = pp->obuf;
/* Fill in TTY function hooks. */
tp->tty_devread = pty_read;
tp->tty_devwrite = pty_write;
tp->tty_echo = pty_echo;
tp->tty_icancel = pty_icancel;
tp->tty_ocancel = pty_ocancel;
tp->tty_close = pty_close;
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tp->tty_select_ops = 0;
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}
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/*==========================================================================*
* pty_status *
*==========================================================================*/
PUBLIC int pty_status(message *m_ptr)
{
int i, event_found;
pty_t *pp;
event_found = 0;
for (i= 0, pp = pty_table; i<NR_PTYS; i++, pp++) {
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if ((((pp->state & TTY_CLOSED) && pp->rdleft > 0) ||
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pp->rdcum > 0) &&
pp->rdcaller == m_ptr->m_source)
{
m_ptr->m_type = DEV_REVIVE;
m_ptr->REP_PROC_NR = pp->rdproc;
m_ptr->REP_STATUS = pp->rdcum;
pp->rdleft = pp->rdcum = 0;
event_found = 1;
break;
}
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if ((((pp->state & TTY_CLOSED) && pp->wrleft > 0) ||
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pp->wrcum > 0) &&
pp->wrcaller == m_ptr->m_source)
{
m_ptr->m_type = DEV_REVIVE;
m_ptr->REP_PROC_NR = pp->wrproc;
if (pp->wrcum == 0)
m_ptr->REP_STATUS = EIO;
else
m_ptr->REP_STATUS = pp->wrcum;
pp->wrleft = pp->wrcum = 0;
event_found = 1;
break;
}
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if(pp->select_ready_ops && pp->select_proc == m_ptr->m_source) {
m_ptr->m_type = DEV_IO_READY;
m_ptr->DEV_MINOR = PTYPX_MINOR + i;
m_ptr->DEV_SEL_OPS = pp->select_ready_ops;
pp->select_ready_ops = 0;
event_found = 1;
break;
}
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}
return event_found;
}
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/*==========================================================================*
* select_try_pty *
*==========================================================================*/
PRIVATE int select_try_pty(tty_t *tp, int ops)
{
pty_t *pp = tp->tty_priv;
int r = 0;
if(ops & SEL_WR) {
/* Write won't block on error. */
if (pp->state & TTY_CLOSED) r |= SEL_WR;
else if (pp->wrleft != 0 || pp->wrcum != 0) r |= SEL_WR;
else r |= SEL_WR;
}
if(ops & SEL_RD) {
/* Read won't block on error. */
if (pp->state & TTY_CLOSED) r |= SEL_RD;
else if(pp->rdleft != 0 || pp->rdcum != 0) r |= SEL_RD;
else if(pp->ocount > 0) r |= SEL_RD; /* Actual data. */
}
return r;
}
/*==========================================================================*
* select_retry_pty *
*==========================================================================*/
PUBLIC void select_retry_pty(tty_t *tp)
{
pty_t *pp = tp->tty_priv;
int r;
/* See if the pty side of a pty is ready to return a select. */
if(pp->select_ops && (r=select_try_pty(tp, pp->select_ops))) {
pp->select_ops &= ~r;
pp->select_ready_ops |= r;
notify(pp->select_proc);
}
}
/*==========================================================================*
* pty_select *
*==========================================================================*/
PRIVATE int pty_select(tty_t *tp, message *m)
{
pty_t *pp = tp->tty_priv;
int ops, ready_ops = 0, watch;
ops = m->PROC_NR & (SEL_RD|SEL_WR|SEL_ERR);
watch = (m->PROC_NR & SEL_NOTIFY) ? 1 : 0;
ready_ops = select_try_pty(tp, ops);
if(!ready_ops && ops && watch) {
pp->select_ops |= ops;
pp->select_proc = m->m_source;
}
return ready_ops;
}
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#endif /* NR_PTYS > 0 */