tty_io.c

Linux 1.0 内核C源代码 Linux最早版本代码 由Linus Torvalds亲自书写的

		{
			/*
			 * It worked. Mark the vt to switch to and
			 * return. The process needs to send us a
			 * VT_RELDISP ioctl to complete the switch.
			 */
			vt_cons[fg_console].vt_newvt = new_console;
			return;
		}

		/*
		 * The controlling process has died, so we revert back to
		 * normal operation. In this case, we'll also change back
		 * to KD_TEXT mode. I'm not sure if this is strictly correct
		 * but it saves the agony when the X server dies and the screen
		 * remains blanked due to KD_GRAPHICS! It would be nice to do
		 * this outside of VT_PROCESS but there is no single process
		 * to account for and tracking tty count may be undesirable.
		 */
		vt_cons[fg_console].vc_mode = KD_TEXT;
		clr_vc_kbd_mode(kbd_table + fg_console, VC_RAW);
		clr_vc_kbd_mode(kbd_table + fg_console, VC_MEDIUMRAW);
		vt_cons[fg_console].vt_mode.mode = VT_AUTO;
		vt_cons[fg_console].vt_mode.waitv = 0;
		vt_cons[fg_console].vt_mode.relsig = 0;
		vt_cons[fg_console].vt_mode.acqsig = 0;
		vt_cons[fg_console].vt_mode.frsig = 0;
		vt_cons[fg_console].vt_pid = -1;
		vt_cons[fg_console].vt_newvt = -1;
		/*
		 * Fall through to normal (VT_AUTO) handling of the switch...
		 */
	}

	/*
	 * Ignore all switches in KD_GRAPHICS+VT_AUTO mode
	 */
	if (vt_cons[fg_console].vc_mode == KD_GRAPHICS)
		return;

	complete_change_console(new_console);
}

void wait_for_keypress(void)
{
	sleep_on(&keypress_wait);
}

void stop_tty(struct tty_struct *tty)
{
	if (tty->stopped)
		return;
	tty->stopped = 1;
	if (tty->link && tty->link->packet) {
		tty->ctrl_status &= ~TIOCPKT_START;
		tty->ctrl_status |= TIOCPKT_STOP;
		wake_up_interruptible(&tty->link->secondary.proc_list);
	}
	if (tty->stop)
		(tty->stop)(tty);
	if (IS_A_CONSOLE(tty->line)) {
		set_vc_kbd_led(kbd_table + fg_console, VC_SCROLLOCK);
		set_leds();
	}
}

void start_tty(struct tty_struct *tty)
{
	if (!tty->stopped)
		return;
	tty->stopped = 0;
	if (tty->link && tty->link->packet) {
		tty->ctrl_status &= ~TIOCPKT_STOP;
		tty->ctrl_status |= TIOCPKT_START;
		wake_up_interruptible(&tty->link->secondary.proc_list);
	}
	if (tty->start)
		(tty->start)(tty);
	TTY_WRITE_FLUSH(tty);
	if (IS_A_CONSOLE(tty->line)) {
		clr_vc_kbd_led(kbd_table + fg_console, VC_SCROLLOCK);
		set_leds();
	}
}

/* Perform OPOST processing.  Returns -1 when the write_q becomes full
   and the character must be retried. */

static int opost(unsigned char c, struct tty_struct *tty)
{
	if (FULL(&tty->write_q))
		return -1;
	if (O_OPOST(tty)) {
		switch (c) {
		case '\n':
			if (O_ONLRET(tty))
				tty->column = 0;
			if (O_ONLCR(tty)) {
				if (LEFT(&tty->write_q) < 2)
					return -1;
				put_tty_queue('\r', &tty->write_q);
				tty->column = 0;
			}
			tty->canon_column = tty->column;
			break;
		case '\r':
			if (O_ONOCR(tty) && tty->column == 0)
				return 0;
			if (O_OCRNL(tty)) {
				c = '\n';
				if (O_ONLRET(tty))
					tty->canon_column = tty->column = 0;
				break;
			}
			tty->canon_column = tty->column = 0;
			break;
		case '\t':
			if (O_TABDLY(tty) == XTABS) {
				if (LEFT(&tty->write_q) < 8)
					return -1;
				do
					put_tty_queue(' ', &tty->write_q);
				while (++tty->column % 8);
				return 0;
			}
			tty->column = (tty->column | 7) + 1;
			break;
		case '\b':
			if (tty->column > 0)
				tty->column--;
			break;
		default:
			if (O_OLCUC(tty))
				c = toupper(c);
			if (!iscntrl(c))
				tty->column++;
			break;
		}
	}
	put_tty_queue(c, &tty->write_q);
	return 0;
}

/* Must be called only when L_ECHO(tty) is true. */

static void echo_char(unsigned char c, struct tty_struct *tty)
{
	if (L_ECHOCTL(tty) && iscntrl(c) && c != '\t') {
		opost('^', tty);
		opost(c ^ 0100, tty);
	} else
		opost(c, tty);
}

static void eraser(unsigned char c, struct tty_struct *tty)
{
	enum { ERASE, WERASE, KILL } kill_type;
	int seen_alnums;

	if (tty->secondary.head == tty->canon_head) {
		/* opost('\a', tty); */		/* what do you think? */
		return;
	}
	if (c == ERASE_CHAR(tty))
		kill_type = ERASE;
	else if (c == WERASE_CHAR(tty))
		kill_type = WERASE;
	else {
		if (!L_ECHO(tty)) {
			tty->secondary.head = tty->canon_head;
			return;
		}
		if (!L_ECHOK(tty) || !L_ECHOKE(tty)) {
			tty->secondary.head = tty->canon_head;
			if (tty->erasing) {
				opost('/', tty);
				tty->erasing = 0;
			}
			echo_char(KILL_CHAR(tty), tty);
			/* Add a newline if ECHOK is on and ECHOKE is off. */
			if (L_ECHOK(tty))
				opost('\n', tty);
			return;
		}
		kill_type = KILL;
	}

	seen_alnums = 0;
	while (tty->secondary.head != tty->canon_head) {
		c = LAST(&tty->secondary);
		if (kill_type == WERASE) {
			/* Equivalent to BSD's ALTWERASE. */
			if (isalnum(c) || c == '_')
				seen_alnums++;
			else if (seen_alnums)
				break;
		}
		DEC(tty->secondary.head);
		if (L_ECHO(tty)) {
			if (L_ECHOPRT(tty)) {
				if (!tty->erasing) {
					opost('\\', tty);
					tty->erasing = 1;
				}
				echo_char(c, tty);
			} else if (!L_ECHOE(tty)) {
				echo_char(ERASE_CHAR(tty), tty);
			} else if (c == '\t') {
				unsigned int col = tty->canon_column;
				unsigned long tail = tty->canon_head;

				/* Find the column of the last char. */
				while (tail != tty->secondary.head) {
					c = tty->secondary.buf[tail];
					if (c == '\t')
						col = (col | 7) + 1;
					else if (iscntrl(c)) {
						if (L_ECHOCTL(tty))
							col += 2;
					} else
						col++;
					INC(tail);
				}

				/* Now backup to that column. */
				while (tty->column > col) {
					/* Can't use opost here. */
					put_tty_queue('\b', &tty->write_q);
					tty->column--;
				}
			} else {
				if (iscntrl(c) && L_ECHOCTL(tty)) {
					opost('\b', tty);
					opost(' ', tty);
					opost('\b', tty);
				}
				if (!iscntrl(c) || L_ECHOCTL(tty)) {
					opost('\b', tty);
					opost(' ', tty);
					opost('\b', tty);
				}
			}
		}
		if (kill_type == ERASE)
			break;
	}
	if (tty->erasing && tty->secondary.head == tty->canon_head) {
		opost('/', tty);
		tty->erasing = 0;
	}
}

static void isig(int sig, struct tty_struct *tty)
{
	kill_pg(tty->pgrp, sig, 1);
	if (!L_NOFLSH(tty)) {
		flush_input(tty);
		flush_output(tty);
	}
}

static void copy_to_cooked(struct tty_struct * tty)
{
	int c, special_flag;
	unsigned long flags;

	if (!tty) {
		printk("copy_to_cooked: called with NULL tty\n");
		return;
	}
	if (!tty->write) {
		printk("copy_to_cooked: tty %d has null write routine\n",
		       tty->line);
	}
	while (1) {
		/*
		 * Check to see how much room we have left in the
		 * secondary queue.  Send a throttle command or abort
		 * if necessary.
		 */
		c = LEFT(&tty->secondary);
		if (tty->throttle && (c < SQ_THRESHOLD_LW)
		    && !set_bit(TTY_SQ_THROTTLED, &tty->flags))
			tty->throttle(tty, TTY_THROTTLE_SQ_FULL);
		if (c == 0)
			break;
		save_flags(flags); cli();
		if (!EMPTY(&tty->read_q)) {
			c = tty->read_q.buf[tty->read_q.tail];
			special_flag = clear_bit(tty->read_q.tail,
						 &tty->readq_flags);
			INC(tty->read_q.tail);
			restore_flags(flags);
		} else {
			restore_flags(flags);
			break;
		}
		if (special_flag) {
			tty->char_error = c;
			continue;
		}
		if (tty->char_error) {
			if (tty->char_error == TTY_BREAK) {
				tty->char_error = 0;
				if (I_IGNBRK(tty))
					continue;
				/* A break is handled by the lower levels. */
				if (I_BRKINT(tty))
					continue;
				if (I_PARMRK(tty)) {
					put_tty_queue('\377', &tty->secondary);
					put_tty_queue('\0', &tty->secondary);
				}
				put_tty_queue('\0', &tty->secondary);
				continue;
			}
			if (tty->char_error == TTY_OVERRUN) {
				tty->char_error = 0;
				printk("tty%d: input overrun\n", tty->line);
				continue;
			}
			/* Must be a parity or frame error */
			tty->char_error = 0;
			if (I_IGNPAR(tty)) {
				continue;
			}
			if (I_PARMRK(tty)) {
				put_tty_queue('\377', &tty->secondary);
				put_tty_queue('\0', &tty->secondary);
				put_tty_queue(c, &tty->secondary);
			} else
				put_tty_queue('\0', &tty->secondary);
			continue;
		}
		if (I_ISTRIP(tty))
			c &= 0x7f;
		if (!tty->lnext) {
			if (c == '\r') {
				if (I_IGNCR(tty))
					continue;
				if (I_ICRNL(tty))
					c = '\n';
			} else if (c == '\n' && I_INLCR(tty))
				c = '\r';
		}
		if (I_IUCLC(tty) && L_IEXTEN(tty))
			c=tolower(c);
		if (c == __DISABLED_CHAR)
			tty->lnext = 1;
		if (L_ICANON(tty) && !tty->lnext) {
			if (c == ERASE_CHAR(tty) || c == KILL_CHAR(tty) ||
			    (c == WERASE_CHAR(tty) && L_IEXTEN(tty))) {
				eraser(c, tty);
				continue;
			}
			if (c == LNEXT_CHAR(tty) && L_IEXTEN(tty)) {
				tty->lnext = 1;
				if (L_ECHO(tty)) {
					if (tty->erasing) {
						opost('/', tty);
						tty->erasing = 0;
					}
					if (L_ECHOCTL(tty)) {
						opost('^', tty);
						opost('\b', tty);
					}
				}
				continue;
			}
			if (c == REPRINT_CHAR(tty) && L_ECHO(tty) &&
			    L_IEXTEN(tty)) {
				unsigned long tail = tty->canon_head;

				if (tty->erasing) {
					opost('/', tty);
					tty->erasing = 0;
				}
				echo_char(c, tty);
				opost('\n', tty);
				while (tail != tty->secondary.head) {
					echo_char(tty->secondary.buf[tail],
						  tty);
					INC(tail);
				}
				continue;
			}
		}
		if (I_IXON(tty) && !tty->lnext) {
			if ((tty->stopped && I_IXANY(tty) && L_IEXTEN(tty)) ||
			    c == START_CHAR(tty)) {
				start_tty(tty);
				continue;
			}
			if (c == STOP_CHAR(tty)) {
				stop_tty(tty);
				continue;
			}
		}
		if (L_ISIG(tty) && !tty->lnext) {
			if (c == INTR_CHAR(tty)) {
				isig(SIGINT, tty);
				continue;
			}
			if (c == QUIT_CHAR(tty)) {
				isig(SIGQUIT, tty);
				continue;
			}
			if (c == SUSP_CHAR(tty)) {
				if (!is_orphaned_pgrp(tty->pgrp))
					isig(SIGTSTP, tty);
				continue;
			}
		}

		if (tty->erasing) {
			opost('/', tty);
			tty->erasing = 0;
		}
		if (c == '\n' && !tty->lnext) {
			if (L_ECHO(tty) || (L_ICANON(tty) && L_ECHONL(tty)))
				opost('\n', tty);
		} else if (L_ECHO(tty)) {
			/* Don't echo the EOF char in canonical mode.  Sun
			   handles this differently by echoing the char and
			   then backspacing, but that's a hack. */
			if (c != EOF_CHAR(tty) || !L_ICANON(tty) ||
			    tty->lnext) {
				/* Record the column of first canon char. */
				if (tty->canon_head == tty->secondary.head)
					tty->canon_column = tty->column;
				echo_char(c, tty);
			}
		}

		if (I_PARMRK(tty) && c == (unsigned char) '\377' &&
		    (c != EOF_CHAR(tty) || !L_ICANON(tty) || tty->lnext))
			put_tty_queue(c, &tty->secondary);

		if (L_ICANON(tty) && !tty->lnext &&
		    (c == '\n' || c == EOF_CHAR(tty) || c == EOL_CHAR(tty) ||
		     (c == EOL2_CHAR(tty) && L_IEXTEN(tty)))) {
			if (c == EOF_CHAR(tty))
				c = __DISABLED_CHAR;
			set_bit(tty->secondary.head, &tty->secondary_flags);
			put_tty_queue(c, &tty->secondary);
			tty->canon_head = tty->secondary.head;
			tty->canon_data++;
		} else
			put_tty_queue(c, &tty->secondary);
		tty->lnext = 0;
	}
	if (!EMPTY(&tty->write_q))
		TTY_WRITE_FLUSH(tty);
	if (L_ICANON(tty) ? tty->canon_data : !EMPTY(&tty->secondary))
		wake_up_interruptible(&tty->secondary.proc_list);

	if (tty->throttle && (LEFT(&tty->read_q) >= RQ_THRESHOLD_HW)
	    && clear_bit(TTY_RQ_THROTTLED, &tty->flags))
		tty->throttle(tty, TTY_THROTTLE_RQ_AVAIL);
}

int is_ignored(int sig)