tty_ioctl.c

LINUX1.0内核源代码,学习LINUX编程的一定要看。

/*
 *  linux/kernel/drivers/char/tty_ioctl.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
 * which can be dynamically activated and de-activated by the line
 * discipline handling modules (like SLIP).
 */

#include <linux/types.h>
#include <linux/termios.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/tty.h>
#include <linux/fcntl.h>
#include <linux/string.h>

#include <asm/io.h>
#include <asm/bitops.h>
#include <asm/segment.h>
#include <asm/system.h>

#undef	DEBUG
#ifdef DEBUG
# define	PRINTK(x)	printk (x)
#else
# define	PRINTK(x)	/**/
#endif

extern int session_of_pgrp(int pgrp);
extern int do_screendump(int arg);
extern int kill_pg(int pgrp, int sig, int priv);

#ifdef CONFIG_SELECTION
extern int set_selection(const int arg);
extern int paste_selection(struct tty_struct *tty);
#endif /* CONFIG_SELECTION */

static int tty_set_ldisc(struct tty_struct *tty, int ldisc);

void flush_input(struct tty_struct * tty)
{
	cli();
	tty->read_q.head = tty->read_q.tail = 0;
	tty->secondary.head = tty->secondary.tail = 0;
	tty->canon_head = tty->canon_data = tty->erasing = 0;
	memset(&tty->readq_flags, 0, sizeof tty->readq_flags);
	memset(&tty->secondary_flags, 0, sizeof tty->secondary_flags);
	sti();
	if (!tty->link)
		return;
	/* No cli() since ptys don't use interrupts. */
	tty->link->write_q.head = tty->link->write_q.tail = 0;
	wake_up_interruptible(&tty->link->write_q.proc_list);
	if (tty->link->packet) {
		tty->ctrl_status |= TIOCPKT_FLUSHREAD;
		wake_up_interruptible(&tty->link->secondary.proc_list);
	}
}

void flush_output(struct tty_struct * tty)
{
	cli();
	tty->write_q.head = tty->write_q.tail = 0;
	sti();
	wake_up_interruptible(&tty->write_q.proc_list);
	if (!tty->link)
		return;
	/* No cli() since ptys don't use interrupts. */
	tty->link->read_q.head = tty->link->read_q.tail = 0;
	tty->link->secondary.head = tty->link->secondary.tail = 0;
	tty->link->canon_head = tty->link->canon_data = tty->link->erasing = 0;
	memset(&tty->link->readq_flags, 0, sizeof tty->readq_flags);
	memset(&tty->link->secondary_flags, 0, sizeof tty->secondary_flags);
	if (tty->link->packet) {
		tty->ctrl_status |= TIOCPKT_FLUSHWRITE;
		wake_up_interruptible(&tty->link->secondary.proc_list);
	}
}

void wait_until_sent(struct tty_struct * tty, int timeout)
{
	struct wait_queue wait = { current, NULL };

	TTY_WRITE_FLUSH(tty);
	if (EMPTY(&tty->write_q))
		return;
	add_wait_queue(&tty->write_q.proc_list, &wait);
	current->counter = 0;	/* make us low-priority */
	if (timeout)
		current->timeout = timeout + jiffies;
	else
		current->timeout = (unsigned) -1;
	do {
		current->state = TASK_INTERRUPTIBLE;
		if (current->signal & ~current->blocked)
			break;
		TTY_WRITE_FLUSH(tty);
		if (EMPTY(&tty->write_q))
			break;
		schedule();
	} while (current->timeout);
	current->state = TASK_RUNNING;
	remove_wait_queue(&tty->write_q.proc_list, &wait);
}

static int do_get_ps_info(int arg)
{
	struct tstruct {
		int flag;
		int present[NR_TASKS];
		struct task_struct tasks[NR_TASKS];
	};
	struct tstruct *ts = (struct tstruct *)arg;
	struct task_struct **p;
	char *c, *d;
	int i, n = 0;
	
	i = verify_area(VERIFY_WRITE, (void *)arg, sizeof(struct tstruct));
	if (i)
		return i;
	for (p = &FIRST_TASK ; p <= &LAST_TASK ; p++, n++)
		if (*p)
		{
			c = (char *)(*p);
			d = (char *)(ts->tasks+n);
			for (i=0 ; i<sizeof(struct task_struct) ; i++)
				put_fs_byte(*c++, d++);
			put_fs_long(1, (unsigned long *)(ts->present+n));
		}
		else	
			put_fs_long(0, (unsigned long *)(ts->present+n));
	return(0);			
}

static void unset_locked_termios(struct termios *termios,
				 struct termios *old,
				 struct termios *locked)
{
	int	i;
	
#define NOSET_MASK(x,y,z) (x = ((x) & ~(z)) | ((y) & (z)))

	if (!locked) {
		printk("Warning?!? termios_locked is NULL.\n");
		return;
	}

	NOSET_MASK(termios->c_iflag, old->c_iflag, locked->c_iflag);
	NOSET_MASK(termios->c_oflag, old->c_oflag, locked->c_oflag);
	NOSET_MASK(termios->c_cflag, old->c_cflag, locked->c_cflag);
	NOSET_MASK(termios->c_lflag, old->c_lflag, locked->c_lflag);
	termios->c_line = locked->c_line ? old->c_line : termios->c_line;
	for (i=0; i < NCCS; i++)
		termios->c_cc[i] = locked->c_cc[i] ?
			old->c_cc[i] : termios->c_cc[i];
}

int check_change(struct tty_struct * tty, int channel)
{
	/* If we try to set the state of terminal and we're not in the
	   foreground, send a SIGTTOU.  If the signal is blocked or
	   ignored, go ahead and perform the operation.  POSIX 7.2) */
	if (current->tty != channel)
		return 0;
	if (tty->pgrp <= 0) {
		printk("check_change: tty->pgrp <= 0!\n");
		return 0;
	}
	if (current->pgrp == tty->pgrp)
		return 0;
	if (is_ignored(SIGTTOU))
		return 0;
	if (is_orphaned_pgrp(current->pgrp))
		return -EIO;
	(void) kill_pg(current->pgrp,SIGTTOU,1);
	return -ERESTARTSYS;
}

static int set_termios_2(struct tty_struct * tty, struct termios * termios)
{
	struct termios old_termios = *tty->termios;
	int canon_change;

	canon_change = (old_termios.c_lflag ^ termios->c_lflag) & ICANON;
	cli();
	*tty->termios = *termios;
	if (canon_change) {
		memset(&tty->secondary_flags, 0, sizeof tty->secondary_flags);
		tty->canon_head = tty->secondary.tail;
		tty->canon_data = 0;
		tty->erasing = 0;
	}
	sti();
	if (canon_change && !L_ICANON(tty) && !EMPTY(&tty->secondary))
		/* Get characters left over from canonical mode. */
		wake_up_interruptible(&tty->secondary.proc_list);

	/* see if packet mode change of state */

	if (tty->link && tty->link->packet) {
		int old_flow = ((old_termios.c_iflag & IXON) &&
				(old_termios.c_cc[VSTOP] == '\023') &&
				(old_termios.c_cc[VSTART] == '\021'));
		int new_flow = (I_IXON(tty) &&
				STOP_CHAR(tty) == '\023' &&
				START_CHAR(tty) == '\021');
		if (old_flow != new_flow) {
			tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP);
			if (new_flow)
				tty->ctrl_status |= TIOCPKT_DOSTOP;
			else
				tty->ctrl_status |= TIOCPKT_NOSTOP;
			wake_up_interruptible(&tty->link->secondary.proc_list);
		}
	}

	unset_locked_termios(tty->termios, &old_termios,
			     termios_locked[tty->line]);

	if (tty->set_termios)
		(*tty->set_termios)(tty, &old_termios);

	return 0;
}

static int set_termios(struct tty_struct * tty, struct termios * termios,
		       int channel)
{
	struct termios tmp_termios;

	memcpy_fromfs(&tmp_termios, termios, sizeof (struct termios));
	return set_termios_2(tty, &tmp_termios);
}

static int get_termio(struct tty_struct * tty, struct termio * termio)
{
	int i;
	struct termio tmp_termio;

	i = verify_area(VERIFY_WRITE, termio, sizeof (struct termio));
	if (i)
		return i;
	tmp_termio.c_iflag = tty->termios->c_iflag;
	tmp_termio.c_oflag = tty->termios->c_oflag;
	tmp_termio.c_cflag = tty->termios->c_cflag;
	tmp_termio.c_lflag = tty->termios->c_lflag;
	tmp_termio.c_line = tty->termios->c_line;
	for(i=0 ; i < NCC ; i++)
		tmp_termio.c_cc[i] = tty->termios->c_cc[i];
	memcpy_tofs(termio, &tmp_termio, sizeof (struct termio));
	return 0;
}

static int set_termio(struct tty_struct * tty, struct termio * termio,
		      int channel)
{
	struct termio tmp_termio;
	struct termios tmp_termios;

	tmp_termios = *tty->termios;
	memcpy_fromfs(&tmp_termio, termio, sizeof (struct termio));

#define SET_LOW_BITS(x,y)	((x) = (0xffff0000 & (x)) | (y))

	SET_LOW_BITS(tmp_termios.c_iflag, tmp_termio.c_iflag);
	SET_LOW_BITS(tmp_termios.c_oflag, tmp_termio.c_oflag);
	SET_LOW_BITS(tmp_termios.c_cflag, tmp_termio.c_cflag);
	SET_LOW_BITS(tmp_termios.c_lflag, tmp_termio.c_lflag);
	memcpy(&tmp_termios.c_cc, &tmp_termio.c_cc, NCC);

#undef SET_LOW_BITS

	return set_termios_2(tty, &tmp_termios);
}

static int set_window_size(struct tty_struct * tty, struct winsize * ws)
{
	struct winsize tmp_ws;

	memcpy_fromfs(&tmp_ws, ws, sizeof (struct winsize));
	if (memcmp(&tmp_ws, &tty->winsize, sizeof (struct winsize)) &&
	    tty->pgrp > 0)
		kill_pg(tty->pgrp, SIGWINCH, 1);
	tty->winsize = tmp_ws;
	return 0;
}

/* Set the discipline of a tty line. */
static int tty_set_ldisc(struct tty_struct *tty, int ldisc)
{
	if ((ldisc < N_TTY) || (ldisc >= NR_LDISCS) ||
	    !(ldiscs[ldisc].flags & LDISC_FLAG_DEFINED))
		return -EINVAL;

	if (tty->disc == ldisc)
		return 0;	/* We are already in the desired discipline */

	/* Shutdown the current discipline. */
	wait_until_sent(tty, 0);
	flush_input(tty);
	if (ldiscs[tty->disc].close)
		ldiscs[tty->disc].close(tty);

	/* Now set up the new line discipline. */
	tty->disc = ldisc;
	tty->termios->c_line = ldisc;
	if (ldiscs[tty->disc].open)
		return(ldiscs[tty->disc].open(tty));
	else
		return 0;
}

static unsigned long inq_canon(struct tty_struct * tty)
{
	int nr, head, tail;

	if (!tty->canon_data)
		return 0;
	head = tty->canon_head;
	tail = tty->secondary.tail;
	nr = (head - tail) & (TTY_BUF_SIZE-1);
	/* Skip EOF-chars.. */
	while (head != tail) {
		if (test_bit(tail, &tty->secondary_flags) &&
		    tty->secondary.buf[tail] == __DISABLED_CHAR)
			nr--;
		INC(tail);
	}
	return nr;
}