vt.c

来自「linux 内核源代码」· C语言 代码 · 共 2,565 行 · 第 1/5 页

	unsigned long draw_from = 0, draw_to = 0;
	struct vc_data *vc;
	unsigned char vc_attr;
	uint8_t rescan;
	uint8_t inverse;
	uint8_t width;
	u16 himask, charmask;
	const unsigned char *orig_buf = NULL;
	int orig_count;

	if (in_interrupt())
		return count;

	might_sleep();

	acquire_console_sem();
	vc = tty->driver_data;
	if (vc == NULL) {
		printk(KERN_ERR "vt: argh, driver_data is NULL !\n");
		release_console_sem();
		return 0;
	}

	currcons = vc->vc_num;
	if (!vc_cons_allocated(currcons)) {
	    /* could this happen? */
	    static int error = 0;
	    if (!error) {
		error = 1;
		printk("con_write: tty %d not allocated\n", currcons+1);
	    }
	    release_console_sem();
	    return 0;
	}
	release_console_sem();

	orig_buf = buf;
	orig_count = count;

	/* At this point 'buf' is guaranteed to be a kernel buffer
	 * and therefore no access to userspace (and therefore sleeping)
	 * will be needed.  The con_buf_mtx serializes all tty based
	 * console rendering and vcs write/read operations.  We hold
	 * the console spinlock during the entire write.
	 */

	acquire_console_sem();

	vc = tty->driver_data;
	if (vc == NULL) {
		printk(KERN_ERR "vt: argh, driver_data _became_ NULL !\n");
		release_console_sem();
		goto out;
	}

	himask = vc->vc_hi_font_mask;
	charmask = himask ? 0x1ff : 0xff;

	/* undraw cursor first */
	if (IS_FG(vc))
		hide_cursor(vc);

	while (!tty->stopped && count) {
		int orig = *buf;
		c = orig;
		buf++;
		n++;
		count--;
		rescan = 0;
		inverse = 0;
		width = 1;

		/* Do no translation at all in control states */
		if (vc->vc_state != ESnormal) {
			tc = c;
		} else if (vc->vc_utf && !vc->vc_disp_ctrl) {
		    /* Combine UTF-8 into Unicode in vc_utf_char.
		     * vc_utf_count is the number of continuation bytes still
		     * expected to arrive.
		     * vc_npar is the number of continuation bytes arrived so
		     * far
		     */
rescan_last_byte:
		    if ((c & 0xc0) == 0x80) {
			/* Continuation byte received */
			static const uint32_t utf8_length_changes[] = { 0x0000007f, 0x000007ff, 0x0000ffff, 0x001fffff, 0x03ffffff, 0x7fffffff };
			if (vc->vc_utf_count) {
			    vc->vc_utf_char = (vc->vc_utf_char << 6) | (c & 0x3f);
			    vc->vc_npar++;
			    if (--vc->vc_utf_count) {
				/* Still need some bytes */
				continue;
			    }
			    /* Got a whole character */
			    c = vc->vc_utf_char;
			    /* Reject overlong sequences */
			    if (c <= utf8_length_changes[vc->vc_npar - 1] ||
					c > utf8_length_changes[vc->vc_npar])
				c = 0xfffd;
			} else {
			    /* Unexpected continuation byte */
			    vc->vc_utf_count = 0;
			    c = 0xfffd;
			}
		    } else {
			/* Single ASCII byte or first byte of a sequence received */
			if (vc->vc_utf_count) {
			    /* Continuation byte expected */
			    rescan = 1;
			    vc->vc_utf_count = 0;
			    c = 0xfffd;
			} else if (c > 0x7f) {
			    /* First byte of a multibyte sequence received */
			    vc->vc_npar = 0;
			    if ((c & 0xe0) == 0xc0) {
				vc->vc_utf_count = 1;
				vc->vc_utf_char = (c & 0x1f);
			    } else if ((c & 0xf0) == 0xe0) {
				vc->vc_utf_count = 2;
				vc->vc_utf_char = (c & 0x0f);
			    } else if ((c & 0xf8) == 0xf0) {
				vc->vc_utf_count = 3;
				vc->vc_utf_char = (c & 0x07);
			    } else if ((c & 0xfc) == 0xf8) {
				vc->vc_utf_count = 4;
				vc->vc_utf_char = (c & 0x03);
			    } else if ((c & 0xfe) == 0xfc) {
				vc->vc_utf_count = 5;
				vc->vc_utf_char = (c & 0x01);
			    } else {
				/* 254 and 255 are invalid */
				c = 0xfffd;
			    }
			    if (vc->vc_utf_count) {
				/* Still need some bytes */
				continue;
			    }
			}
			/* Nothing to do if an ASCII byte was received */
		    }
		    /* End of UTF-8 decoding. */
		    /* c is the received character, or U+FFFD for invalid sequences. */
		    /* Replace invalid Unicode code points with U+FFFD too */
		    if ((c >= 0xd800 && c <= 0xdfff) || c == 0xfffe || c == 0xffff)
			c = 0xfffd;
		    tc = c;
		} else {	/* no utf or alternate charset mode */
		    tc = vc->vc_translate[vc->vc_toggle_meta ? (c | 0x80) : c];
		}

                /* If the original code was a control character we
                 * only allow a glyph to be displayed if the code is
                 * not normally used (such as for cursor movement) or
                 * if the disp_ctrl mode has been explicitly enabled.
                 * Certain characters (as given by the CTRL_ALWAYS
                 * bitmap) are always displayed as control characters,
                 * as the console would be pretty useless without
                 * them; to display an arbitrary font position use the
                 * direct-to-font zone in UTF-8 mode.
                 */
                ok = tc && (c >= 32 ||
			    !(vc->vc_disp_ctrl ? (CTRL_ALWAYS >> c) & 1 :
				  vc->vc_utf || ((CTRL_ACTION >> c) & 1)))
			&& (c != 127 || vc->vc_disp_ctrl)
			&& (c != 128+27);

		if (vc->vc_state == ESnormal && ok) {
			if (vc->vc_utf && !vc->vc_disp_ctrl) {
				if (is_double_width(c))
					width = 2;
			}
			/* Now try to find out how to display it */
			tc = conv_uni_to_pc(vc, tc);
			if (tc & ~charmask) {
				if (tc == -1 || tc == -2) {
				    continue; /* nothing to display */
				}
				/* Glyph not found */
				if ((!(vc->vc_utf && !vc->vc_disp_ctrl) || c < 128) && !(c & ~charmask)) {
				    /* In legacy mode use the glyph we get by a 1:1 mapping.
				       This would make absolutely no sense with Unicode in mind,
				       but do this for ASCII characters since a font may lack
				       Unicode mapping info and we don't want to end up with
				       having question marks only. */
				    tc = c;
				} else {
				    /* Display U+FFFD. If it's not found, display an inverse question mark. */
				    tc = conv_uni_to_pc(vc, 0xfffd);
				    if (tc < 0) {
					inverse = 1;
					tc = conv_uni_to_pc(vc, '?');
					if (tc < 0) tc = '?';
				    }
				}
			}

			if (!inverse) {
				vc_attr = vc->vc_attr;
			} else {
				/* invert vc_attr */
				if (!vc->vc_can_do_color) {
					vc_attr = (vc->vc_attr) ^ 0x08;
				} else if (vc->vc_hi_font_mask == 0x100) {
					vc_attr = ((vc->vc_attr) & 0x11) | (((vc->vc_attr) & 0xe0) >> 4) | (((vc->vc_attr) & 0x0e) << 4);
				} else {
					vc_attr = ((vc->vc_attr) & 0x88) | (((vc->vc_attr) & 0x70) >> 4) | (((vc->vc_attr) & 0x07) << 4);
				}
				FLUSH
			}

			while (1) {
				if (vc->vc_need_wrap || vc->vc_decim)
					FLUSH
				if (vc->vc_need_wrap) {
					cr(vc);
					lf(vc);
				}
				if (vc->vc_decim)
					insert_char(vc, 1);
				scr_writew(himask ?
					     ((vc_attr << 8) & ~himask) + ((tc & 0x100) ? himask : 0) + (tc & 0xff) :
					     (vc_attr << 8) + tc,
					   (u16 *) vc->vc_pos);
				if (DO_UPDATE(vc) && draw_x < 0) {
					draw_x = vc->vc_x;
					draw_from = vc->vc_pos;
				}
				if (vc->vc_x == vc->vc_cols - 1) {
					vc->vc_need_wrap = vc->vc_decawm;
					draw_to = vc->vc_pos + 2;
				} else {
					vc->vc_x++;
					draw_to = (vc->vc_pos += 2);
				}

				if (!--width) break;

				tc = conv_uni_to_pc(vc, ' '); /* A space is printed in the second column */
				if (tc < 0) tc = ' ';
			}
			notify_write(vc, c);

			if (inverse) {
				FLUSH
			}

			if (rescan) {
				rescan = 0;
				inverse = 0;
				width = 1;
				c = orig;
				goto rescan_last_byte;
			}
			continue;
		}
		FLUSH
		do_con_trol(tty, vc, orig);
	}
	FLUSH
	console_conditional_schedule();
	release_console_sem();

out:
	notify_update(vc);
	return n;
#undef FLUSH
}

/*
 * This is the console switching callback.
 *
 * Doing console switching in a process context allows
 * us to do the switches asynchronously (needed when we want
 * to switch due to a keyboard interrupt).  Synchronization
 * with other console code and prevention of re-entrancy is
 * ensured with console_sem.
 */
static void console_callback(struct work_struct *ignored)
{
	acquire_console_sem();

	if (want_console >= 0) {
		if (want_console != fg_console &&
		    vc_cons_allocated(want_console)) {
			hide_cursor(vc_cons[fg_console].d);
			change_console(vc_cons[want_console].d);
			/* we only changed when the console had already
			   been allocated - a new console is not created
			   in an interrupt routine */
		}
		want_console = -1;
	}
	if (do_poke_blanked_console) { /* do not unblank for a LED change */
		do_poke_blanked_console = 0;
		poke_blanked_console();
	}
	if (scrollback_delta) {
		struct vc_data *vc = vc_cons[fg_console].d;
		clear_selection();
		if (vc->vc_mode == KD_TEXT)
			vc->vc_sw->con_scrolldelta(vc, scrollback_delta);
		scrollback_delta = 0;
	}
	if (blank_timer_expired) {
		do_blank_screen(0);
		blank_timer_expired = 0;
	}
	notify_update(vc_cons[fg_console].d);

	release_console_sem();
}

int set_console(int nr)
{
	struct vc_data *vc = vc_cons[fg_console].d;

	if (!vc_cons_allocated(nr) || vt_dont_switch ||
		(vc->vt_mode.mode == VT_AUTO && vc->vc_mode == KD_GRAPHICS)) {

		/*
		 * Console switch will fail in console_callback() or
		 * change_console() so there is no point scheduling
		 * the callback
		 *
		 * Existing set_console() users don't check the return
		 * value so this shouldn't break anything
		 */
		return -EINVAL;
	}

	want_console = nr;
	schedule_console_callback();

	return 0;
}

struct tty_driver *console_driver;

#ifdef CONFIG_VT_CONSOLE

/*
 *	Console on virtual terminal
 *
 * The console must be locked when we get here.
 */

static void vt_console_print(struct console *co, const char *b, unsigned count)
{
	struct vc_data *vc = vc_cons[fg_console].d;
	unsigned char c;
	static unsigned long printing;
	const ushort *start;
	ushort cnt = 0;
	ushort myx;

	/* console busy or not yet initialized */
	if (!printable || test_and_set_bit(0, &printing))
		return;

	if (kmsg_redirect && vc_cons_allocated(kmsg_redirect - 1))
		vc = vc_cons[kmsg_redirect - 1].d;

	/* read `x' only after setting currcons properly (otherwise
	   the `x' macro will read the x of the foreground console). */
	myx = vc->vc_x;

	if (!vc_cons_allocated(fg_console)) {
		/* impossible */
		/* printk("vt_console_print: tty %d not allocated ??\n", currcons+1); */
		goto quit;
	}

	if (vc->vc_mode != KD_TEXT)
		goto quit;

	/* undraw cursor first */
	if (IS_FG(vc))
		hide_cursor(vc);

	start = (ushort *)vc->vc_pos;

	/* Contrived structure to try to emulate original need_wrap behaviour
	 * Problems caused when we have need_wrap set on '\n' character */
	while (count--) {
		c = *b++;
		if (c == 10 || c == 13 || c == 8 || vc->vc_need_wrap) {
			if (cnt > 0) {
				if (CON_IS_VISIBLE(vc))
					vc->vc_sw->con_putcs(vc, start, cnt, vc->vc_y, vc->vc_x);
				vc->vc_x += cnt;
				if (vc->vc_need_wrap)
					vc->vc_x--;
				cnt = 0;
			}
			if (c == 8) {		/* backspace */
				bs(vc);
				start = (ushort *)vc->vc_pos;
				myx = vc->vc_x;
				continue;
			}
			if (c != 13)
				lf(vc);
			cr(vc);
			start = (ushort *)vc->vc_pos;
			myx = vc->vc_x;
			if (c == 10 || c == 13)
				continue;
		}
		scr_writew((vc->vc_attr << 8) + c, (unsigned short *)vc->vc_pos);
		notify_write(vc, c);
		cnt++;
		if (myx == vc->vc_cols - 1) {
			vc->vc_need_wrap = 1;
			continue;
		}
		vc->vc_pos += 2;
		myx++;
	}
	if (cnt > 0) {
		if (CON_IS_VISIBLE(vc))
			vc->vc_sw->con_putcs(vc, start, cnt, vc->vc_y, vc->vc_x);
		vc->vc_x += cnt;
		if (vc->vc_x == vc->vc_cols) {
			vc->vc_x--;
			vc->vc_need_wrap = 1;
		}
	}
	set_cursor(vc);
	notify_update(vc);

quit:
	clear_bit(0, &printing);
}

static struct tty_driver *vt_console_device(struct console *c, int *index)
{
	*index = c->index ? c->index-1 : fg_console;
	return console_driver;
}

static struct console vt_console_driver = {
	.name		= "tty",
	.write		= vt_console_print,
	.device		= vt_console_device,
	.unblank	= unblank_screen,
	.flags		= CON_PRINTBUFFER,
	.index		= -1,
};
#endif

/*
 *	Handling of Linux-specific VC ioctls
 */

/*
 * Generally a bit racy with respect to console_sem().
 *
 * There are some functions which don't need it.
 *
 * There are some functions which can sleep for arbitrary periods
 * (paste_selection) but we don't need the lock there anyway.
 *
 * set_selection has locking, and definitely needs it
 */

int tioclinux(struct tty_struct *tty, unsigned long arg)
{
	char type, data;
	char __user *p = (char __user *)arg;
	int lines;
	int ret;

	if (tty->driver->type != TTY_DRIVER_TYPE_CONSOLE)
		return -EINVAL;
	if (current->signal->tty != tty && !capable(CAP_SYS_ADMIN))
		return -EPERM;
	if (get_user(type, p))
		return -EFAULT;
	ret = 0;
	switch (type)
	{
		case TIOCL_SETSEL:
			acquire_console_sem();
			ret = set_selection((struct tiocl_selection __user *)(p+1), tty);
			release_console_sem();
			break;
		case TIOCL_PASTESEL:
			ret = paste_selection(tty);
			break;
		case TIOCL_UNBLANKSCREEN:
			acquire_console_sem();
			unblank_screen();
			release_console_sem();
			break;
		case TIOCL_SELLOADLUT:
			ret = sel_loadlut(p);
			break;
		case TIOCL_GETSHIFTSTATE:
			
	/*
	 * Make it possible to react to Shift+Mousebutton.
	 * Note that 'shift_state' is an undocumented
	 * kernel-internal variable; programs not closely
	 * related to the kernel should not use this.
	 */
	 		data = shift_state;
			ret = __put_user(data, p);
			break;
		case TIOCL_GETMOUSEREPORTING:
			data = mouse_reporting();
			ret = __put_user(data, p);
			break;
		case TIO