sanchayanmaity/minix
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

TTY: fix for PTY open/close logic

Browse source 
Opening and closing the master side of a pseudo terminal without
opening the slave side would result in the pseudo terminal becoming
permanently unavailable.  In addition, reopening the slave side
would be possible but not allow for I/O.  Finally, attempting to
open an in-use master would wipe its I/O state.  These issues have
been resolved.

Change-Id: I9235e3d9aba321803f9280b86b6b5e3646ad5ef3
This commit is contained in:
David van Moolenbroek 2013-08-31 16:08:25 +02:00 committed by Lionel Sambuc
parent 836894a219
commit 20173cb5d7
1 changed files with 34 additions and 9 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

37
drivers/tty/pty.c
View file

@ -59,9 +59,10 @@ typedef struct pty {
dev_t select_minor; /* sanity check only, can be removed */
} 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 */
#define TTY_ACTIVE 0x01 /* tty is open/active */
#define PTY_ACTIVE 0x02 /* pty is open/active */
#define TTY_CLOSED 0x04 /* tty side has closed down */
#define PTY_CLOSED 0x08 /* pty side has closed down */
static pty_t pty_table[NR_PTYS]; /* PTY bookkeeping */
@ -164,16 +165,20 @@ void do_pty(tty_t *tp, message *m_ptr)
break;
case DEV_OPEN:
r = pp->state != 0 ? EIO : OK;
if (!(pp->state & PTY_ACTIVE)) {
pp->state |= PTY_ACTIVE;
pp->rdcum = 0;
pp->wrcum = 0;
r = OK;
} else {
r = EIO;
}
tty_reply(DEV_OPEN_REPL, m_ptr->m_source, m_ptr->USER_ENDPT,
(cp_grant_id_t) m_ptr->IO_GRANT, r);
return;
case DEV_CLOSE:
if (pp->state & TTY_CLOSED) {
if ((pp->state & (TTY_ACTIVE | TTY_CLOSED)) != TTY_ACTIVE) {
pp->state = 0;
} else {
pp->state |= PTY_CLOSED;
@ -411,6 +416,24 @@ static int pty_read(tty_t *tp, int try)
return 0;
}
/*===========================================================================*
* pty_open *
*===========================================================================*/
static int pty_open(tty_t *tp, int UNUSED(try))
{
/* The tty side has been opened. */
pty_t *pp = tp->tty_priv;
/* TTY_ACTIVE may already be set, which would indicate that the slave is
* reopened after being fully closed while the master is still open. In that
* case TTY_CLOSED will also be set, so clear that one.
*/
pp->state |= TTY_ACTIVE;
pp->state &= ~TTY_CLOSED;
return 0;
}
/*===========================================================================*
* pty_close *
*===========================================================================*/
@ -435,7 +458,8 @@ static int pty_close(tty_t *tp, int UNUSED(try))
pp->wrgrant = GRANT_INVALID;
}
if (pp->state & PTY_CLOSED) pp->state = 0; else pp->state |= TTY_CLOSED;
if (pp->state & PTY_CLOSED) pp->state = 0;
else pp->state |= TTY_CLOSED;
return 0;
}
@ -497,6 +521,7 @@ void pty_init(tty_t *tp)
tp->tty_echo = pty_echo;
tp->tty_icancel = pty_icancel;
tp->tty_ocancel = pty_ocancel;
tp->tty_open = pty_open;
tp->tty_close = pty_close;
tp->tty_select_ops = 0;
}