[linux-2.6-block.git] / drivers / tty / vt / vc_screen.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Provide access to virtual console memory.
 * /dev/vcs: the screen as it is being viewed right now (possibly scrolled)
 * /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63)
 *            [minor: N]
 *
 * /dev/vcsaN: idem, but including attributes, and prefixed with
 *	the 4 bytes lines,columns,x,y (as screendump used to give).
 *	Attribute/character pair is in native endianity.
 *            [minor: N+128]
 *
 * /dev/vcsuN: similar to /dev/vcsaN but using 4-byte unicode values
 *	instead of 1-byte screen glyph values.
 *            [minor: N+64]
 *
 * /dev/vcsuaN: same idea as /dev/vcsaN for unicode (not yet implemented).
 *
 * This replaces screendump and part of selection, so that the system
 * administrator can control access using file system permissions.
 *
 * aeb@cwi.nl - efter Friedas begravelse - 950211
 *
 * machek@k332.feld.cvut.cz - modified not to send characters to wrong console
 *	 - fixed some fatal off-by-one bugs (0-- no longer == -1 -> looping and looping and looping...)
 *	 - making it shorter - scr_readw are macros which expand in PRETTY long code
 */

#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/tty.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/vt_kern.h>
#include <linux/selection.h>
#include <linux/kbd_kern.h>
#include <linux/console.h>
#include <linux/device.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/signal.h>
#include <linux/slab.h>
#include <linux/notifier.h>

#include <linux/uaccess.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>

#undef attr
#undef org
#undef addr
#define HEADER_SIZE	4

#define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE)

/*
 * Our minor space:
 *
 *   0 ... 63	glyph mode without attributes
 *  64 ... 127	unicode mode without attributes
 * 128 ... 191	glyph mode with attributes
 * 192 ... 255	unused (reserved for unicode with attributes)
 *
 * This relies on MAX_NR_CONSOLES being  <= 63, meaning 63 actual consoles
 * with minors 0, 64, 128 and 192 being proxies for the foreground console.
 */
#if MAX_NR_CONSOLES > 63
#warning "/dev/vcs* devices may not accommodate more than 63 consoles"
#endif

#define console(inode)		(iminor(inode) & 63)
#define use_unicode(inode)	(iminor(inode) & 64)
#define use_attributes(inode)	(iminor(inode) & 128)


struct vcs_poll_data {
	struct notifier_block notifier;
	unsigned int cons_num;
	int event;
	wait_queue_head_t waitq;
	struct fasync_struct *fasync;
};

static int
vcs_notifier(struct notifier_block *nb, unsigned long code, void *_param)
{
	struct vt_notifier_param *param = _param;
	struct vc_data *vc = param->vc;
	struct vcs_poll_data *poll =
		container_of(nb, struct vcs_poll_data, notifier);
	int currcons = poll->cons_num;
	int fa_band;

	switch (code) {
	case VT_UPDATE:
		fa_band = POLL_PRI;
		break;
	case VT_DEALLOCATE:
		fa_band = POLL_HUP;
		break;
	default:
		return NOTIFY_DONE;
	}

	if (currcons == 0)
		currcons = fg_console;
	else
		currcons--;
	if (currcons != vc->vc_num)
		return NOTIFY_DONE;

	poll->event = code;
	wake_up_interruptible(&poll->waitq);
	kill_fasync(&poll->fasync, SIGIO, fa_band);
	return NOTIFY_OK;
}

static void
vcs_poll_data_free(struct vcs_poll_data *poll)
{
	unregister_vt_notifier(&poll->notifier);
	kfree(poll);
}

static struct vcs_poll_data *
vcs_poll_data_get(struct file *file)
{
	struct vcs_poll_data *poll = file->private_data, *kill = NULL;

	if (poll)
		return poll;

	poll = kzalloc(sizeof(*poll), GFP_KERNEL);
	if (!poll)
		return NULL;
	poll->cons_num = console(file_inode(file));
	init_waitqueue_head(&poll->waitq);
	poll->notifier.notifier_call = vcs_notifier;
	/*
	 * In order not to lose any update event, we must pretend one might
	 * have occurred before we have a chance to register our notifier.
	 * This is also how user space has come to detect which kernels
	 * support POLLPRI on /dev/vcs* devices i.e. using poll() with
	 * POLLPRI and a zero timeout.
	 */
	poll->event = VT_UPDATE;

	if (register_vt_notifier(&poll->notifier) != 0) {
		kfree(poll);
		return NULL;
	}

	/*
	 * This code may be called either through ->poll() or ->fasync().
	 * If we have two threads using the same file descriptor, they could
	 * both enter this function, both notice that the structure hasn't
	 * been allocated yet and go ahead allocating it in parallel, but
	 * only one of them must survive and be shared otherwise we'd leak
	 * memory with a dangling notifier callback.
	 */
	spin_lock(&file->f_lock);
	if (!file->private_data) {
		file->private_data = poll;
	} else {
		/* someone else raced ahead of us */
		kill = poll;
		poll = file->private_data;
	}
	spin_unlock(&file->f_lock);
	if (kill)
		vcs_poll_data_free(kill);

	return poll;
}

/*
 * Returns VC for inode.
 * Must be called with console_lock.
 */
static struct vc_data*
vcs_vc(struct inode *inode, int *viewed)
{
	unsigned int currcons = console(inode);

	WARN_CONSOLE_UNLOCKED();

	if (currcons == 0) {
		currcons = fg_console;
		if (viewed)
			*viewed = 1;
	} else {
		currcons--;
		if (viewed)
			*viewed = 0;
	}
	return vc_cons[currcons].d;
}

/*
 * Returns size for VC carried by inode.
 * Must be called with console_lock.
 */
static int
vcs_size(struct inode *inode)
{
	int size;
	struct vc_data *vc;

	WARN_CONSOLE_UNLOCKED();

	vc = vcs_vc(inode, NULL);
	if (!vc)
		return -ENXIO;

	size = vc->vc_rows * vc->vc_cols;

	if (use_attributes(inode)) {
		if (use_unicode(inode))
			return -EOPNOTSUPP;
		size = 2*size + HEADER_SIZE;
	} else if (use_unicode(inode))
		size *= 4;
	return size;
}

static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
{
	int size;

	console_lock();
	size = vcs_size(file_inode(file));
	console_unlock();
	if (size < 0)
		return size;
	return fixed_size_llseek(file, offset, orig, size);
}


static ssize_t
vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
	struct inode *inode = file_inode(file);
	struct vc_data *vc;
	struct vcs_poll_data *poll;
	long pos, read;
	int attr, uni_mode, row, col, maxcol, viewed;
	unsigned short *org = NULL;
	ssize_t ret;
	char *con_buf;

	con_buf = (char *) __get_free_page(GFP_KERNEL);
	if (!con_buf)
		return -ENOMEM;

	pos = *ppos;

	/* Select the proper current console and verify
	 * sanity of the situation under the console lock.
	 */
	console_lock();

	uni_mode = use_unicode(inode);
	attr = use_attributes(inode);
	ret = -ENXIO;
	vc = vcs_vc(inode, &viewed);
	if (!vc)
		goto unlock_out;

	ret = -EINVAL;
	if (pos < 0)
		goto unlock_out;
	/* we enforce 32-bit alignment for pos and count in unicode mode */
	if (uni_mode && (pos | count) & 3)
		goto unlock_out;

	poll = file->private_data;
	if (count && poll)
		poll->event = 0;
	read = 0;
	ret = 0;
	while (count) {
		char *con_buf0, *con_buf_start;
		long this_round, size;
		ssize_t orig_count;
		long p = pos;

		/* Check whether we are above size each round,
		 * as copy_to_user at the end of this loop
		 * could sleep.
		 */
		size = vcs_size(inode);
		if (size < 0) {
			if (read)
				break;
			ret = size;
			goto unlock_out;
		}
		if (pos >= size)
			break;
		if (count > size - pos)
			count = size - pos;

		this_round = count;
		if (this_round > CON_BUF_SIZE)
			this_round = CON_BUF_SIZE;

		/* Perform the whole read into the local con_buf.
		 * Then we can drop the console spinlock and safely
		 * attempt to move it to userspace.
		 */

		con_buf_start = con_buf0 = con_buf;
		orig_count = this_round;
		maxcol = vc->vc_cols;
		if (uni_mode) {
			unsigned int nr;

			ret = vc_uniscr_check(vc);
			if (ret)
				break;
			p /= 4;
			row = p / vc->vc_cols;
			col = p % maxcol;
			nr = maxcol - col;
			do {
				if (nr > this_round/4)
					nr = this_round/4;
				vc_uniscr_copy_line(vc, con_buf0, viewed,
						    row, col, nr);
				con_buf0 += nr * 4;
				this_round -= nr * 4;
				row++;
				col = 0;
				nr = maxcol;
			} while (this_round);
		} else if (!attr) {
			org = screen_pos(vc, p, viewed);
			col = p % maxcol;
			p += maxcol - col;
			while (this_round-- > 0) {
				*con_buf0++ = (vcs_scr_readw(vc, org++) & 0xff);
				if (++col == maxcol) {
					org = screen_pos(vc, p, viewed);
					col = 0;
					p += maxcol;
				}
			}
		} else {
			if (p < HEADER_SIZE) {
				size_t tmp_count;

				/* clamp header values if they don't fit */
				con_buf0[0] = min(vc->vc_rows, 0xFFu);
				con_buf0[1] = min(vc->vc_cols, 0xFFu);
				getconsxy(vc, con_buf0 + 2);

				con_buf_start += p;
				this_round += p;
				if (this_round > CON_BUF_SIZE) {
					this_round = CON_BUF_SIZE;
					orig_count = this_round - p;
				}

				tmp_count = HEADER_SIZE;
				if (tmp_count > this_round)
					tmp_count = this_round;

				/* Advance state pointers and move on. */
				this_round -= tmp_count;
				p = HEADER_SIZE;
				con_buf0 = con_buf + HEADER_SIZE;
				/* If this_round >= 0, then p is even... */
			} else if (p & 1) {
				/* Skip first byte for output if start address is odd
				 * Update region sizes up/down depending on free
				 * space in buffer.
				 */
				con_buf_start++;
				if (this_round < CON_BUF_SIZE)
					this_round++;
				else
					orig_count--;
			}
			if (this_round > 0) {
				unsigned short *tmp_buf = (unsigned short *)con_buf0;

				p -= HEADER_SIZE;
				p /= 2;
				col = p % maxcol;

				org = screen_pos(vc, p, viewed);
				p += maxcol - col;

				/* Buffer has even length, so we can always copy
				 * character + attribute. We do not copy last byte
				 * to userspace if this_round is odd.
				 */
				this_round = (this_round + 1) >> 1;

				while (this_round) {
					*tmp_buf++ = vcs_scr_readw(vc, org++);
					this_round --;
					if (++col == maxcol) {
						org = screen_pos(vc, p, viewed);
						col = 0;
						p += maxcol;
					}
				}
			}
		}

		/* Finally, release the console semaphore while we push
		 * all the data to userspace from our temporary buffer.
		 *
		 * AKPM: Even though it's a semaphore, we should drop it because
		 * the pagefault handling code may want to call printk().
		 */

		console_unlock();
		ret = copy_to_user(buf, con_buf_start, orig_count);
		console_lock();

		if (ret) {
			read += (orig_count - ret);
			ret = -EFAULT;
			break;
		}
		buf += orig_count;
		pos += orig_count;
		read += orig_count;
		count -= orig_count;
	}
	*ppos += read;
	if (read)
		ret = read;
unlock_out:
	console_unlock();
	free_page((unsigned long) con_buf);
	return ret;
}

static ssize_t
vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
	struct inode *inode = file_inode(file);
	struct vc_data *vc;
	long pos;
	long attr, size, written;
	char *con_buf0;
	int col, maxcol, viewed;
	u16 *org0 = NULL, *org = NULL;
	size_t ret;
	char *con_buf;

	con_buf = (char *) __get_free_page(GFP_KERNEL);
	if (!con_buf)
		return -ENOMEM;

	pos = *ppos;

	/* Select the proper current console and verify
	 * sanity of the situation under the console lock.
	 */
	console_lock();

	attr = use_attributes(inode);
	ret = -ENXIO;
	vc = vcs_vc(inode, &viewed);
	if (!vc)
		goto unlock_out;

	size = vcs_size(inode);
	ret = -EINVAL;
	if (pos < 0 || pos > size)
		goto unlock_out;
	if (count > size - pos)
		count = size - pos;
	written = 0;
	while (count) {
		long this_round = count;
		size_t orig_count;
		long p;

		if (this_round > CON_BUF_SIZE)
			this_round = CON_BUF_SIZE;

		/* Temporarily drop the console lock so that we can read
		 * in the write data from userspace safely.
		 */
		console_unlock();
		ret = copy_from_user(con_buf, buf, this_round);
		console_lock();

		if (ret) {
			this_round -= ret;
			if (!this_round) {
				/* Abort loop if no data were copied. Otherwise
				 * fail with -EFAULT.
				 */
				if (written)
					break;
				ret = -EFAULT;
				goto unlock_out;
			}
		}

		/* The vcs_size might have changed while we slept to grab
		 * the user buffer, so recheck.
		 * Return data written up to now on failure.
		 */
		size = vcs_size(inode);
		if (size < 0) {
			if (written)
				break;
			ret = size;
			goto unlock_out;
		}
		if (pos >= size)
			break;
		if (this_round > size - pos)
			this_round = size - pos;

		/* OK, now actually push the write to the console
		 * under the lock using the local kernel buffer.
		 */

		con_buf0 = con_buf;
		orig_count = this_round;
		maxcol = vc->vc_cols;
		p = pos;
		if (!attr) {
			org0 = org = screen_pos(vc, p, viewed);
			col = p % maxcol;
			p += maxcol - col;

			while (this_round > 0) {
				unsigned char c = *con_buf0++;

				this_round--;
				vcs_scr_writew(vc,
					       (vcs_scr_readw(vc, org) & 0xff00) | c, org);
				org++;
				if (++col == maxcol) {
					org = screen_pos(vc, p, viewed);
					col = 0;
					p += maxcol;
				}
			}
		} else {
			if (p < HEADER_SIZE) {
				char header[HEADER_SIZE];

				getconsxy(vc, header + 2);
				while (p < HEADER_SIZE && this_round > 0) {
					this_round--;
					header[p++] = *con_buf0++;
				}
				if (!viewed)
					putconsxy(vc, header + 2);
			}
			p -= HEADER_SIZE;
			col = (p/2) % maxcol;
			if (this_round > 0) {
				org0 = org = screen_pos(vc, p/2, viewed);
				if ((p & 1) && this_round > 0) {
					char c;

					this_round--;
					c = *con_buf0++;
#ifdef __BIG_ENDIAN
					vcs_scr_writew(vc, c |
					     (vcs_scr_readw(vc, org) & 0xff00), org);
#else
					vcs_scr_writew(vc, (c << 8) |
					     (vcs_scr_readw(vc, org) & 0xff), org);
#endif
					org++;
					p++;
					if (++col == maxcol) {
						org = screen_pos(vc, p/2, viewed);
						col = 0;
					}
				}
				p /= 2;
				p += maxcol - col;
			}
			while (this_round > 1) {
				unsigned short w;

				w = get_unaligned(((unsigned short *)con_buf0));
				vcs_scr_writew(vc, w, org++);
				con_buf0 += 2;
				this_round -= 2;
				if (++col == maxcol) {
					org = screen_pos(vc, p, viewed);
					col = 0;
					p += maxcol;
				}
			}
			if (this_round > 0) {
				unsigned char c;

				c = *con_buf0++;
#ifdef __BIG_ENDIAN
				vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) | (c << 8), org);
#else
				vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) | c, org);
#endif
			}
		}
		count -= orig_count;
		written += orig_count;
		buf += orig_count;
		pos += orig_count;
		if (org0)
			update_region(vc, (unsigned long)(org0), org - org0);
	}
	*ppos += written;
	ret = written;
	if (written)
		vcs_scr_updated(vc);

unlock_out:
	console_unlock();
	free_page((unsigned long) con_buf);
	return ret;
}

static __poll_t
vcs_poll(struct file *file, poll_table *wait)
{
	struct vcs_poll_data *poll = vcs_poll_data_get(file);
	__poll_t ret = DEFAULT_POLLMASK|EPOLLERR;

	if (poll) {
		poll_wait(file, &poll->waitq, wait);
		switch (poll->event) {
		case VT_UPDATE:
			ret = DEFAULT_POLLMASK|EPOLLPRI;
			break;
		case VT_DEALLOCATE:
			ret = DEFAULT_POLLMASK|EPOLLHUP|EPOLLERR;
			break;
		case 0:
			ret = DEFAULT_POLLMASK;
			break;
		}
	}
	return ret;
}

static int
vcs_fasync(int fd, struct file *file, int on)
{
	struct vcs_poll_data *poll = file->private_data;

	if (!poll) {
		/* don't allocate anything if all we want is disable fasync */
		if (!on)
			return 0;
		poll = vcs_poll_data_get(file);
		if (!poll)
			return -ENOMEM;
	}

	return fasync_helper(fd, file, on, &poll->fasync);
}

static int
vcs_open(struct inode *inode, struct file *filp)
{
	unsigned int currcons = console(inode);
	bool attr = use_attributes(inode);
	bool uni_mode = use_unicode(inode);
	int ret = 0;

	/* we currently don't support attributes in unicode mode */
	if (attr && uni_mode)
		return -EOPNOTSUPP;

	console_lock();
	if(currcons && !vc_cons_allocated(currcons-1))
		ret = -ENXIO;
	console_unlock();
	return ret;
}

static int vcs_release(struct inode *inode, struct file *file)
{
	struct vcs_poll_data *poll = file->private_data;

	if (poll)
		vcs_poll_data_free(poll);
	return 0;
}

static const struct file_operations vcs_fops = {
	.llseek		= vcs_lseek,
	.read		= vcs_read,
	.write		= vcs_write,
	.poll		= vcs_poll,
	.fasync		= vcs_fasync,
	.open		= vcs_open,
	.release	= vcs_release,
};

static struct class *vc_class;

void vcs_make_sysfs(int index)
{
	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
		      "vcs%u", index + 1);
	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 65), NULL,
		      "vcsu%u", index + 1);
	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
		      "vcsa%u", index + 1);
}

void vcs_remove_sysfs(int index)
{
	device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
	device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 65));
	device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
}

int __init vcs_init(void)
{
	unsigned int i;

	if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
		panic("unable to get major %d for vcs device", VCS_MAJOR);
	vc_class = class_create(THIS_MODULE, "vc");

	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 64), NULL, "vcsu");
	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
	for (i = 0; i < MIN_NR_CONSOLES; i++)
		vcs_make_sysfs(i);
	return 0;
}
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
1da177e4	2	/*
1da177e4	3	* Provide access to virtual console memory.
67fbfc39	4	* /dev/vcs: the screen as it is being viewed right now (possibly scrolled)
1da177e4 LT	5	* /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63)
	6	* [minor: N]
	7	*
	8	* /dev/vcsaN: idem, but including attributes, and prefixed with
	9	* the 4 bytes lines,columns,x,y (as screendump used to give).
	10	* Attribute/character pair is in native endianity.
	11	* [minor: N+128]
	12	*
d21b0be2 NP	13	* /dev/vcsuN: similar to /dev/vcsaN but using 4-byte unicode values
	14	* instead of 1-byte screen glyph values.
	15	* [minor: N+64]
	16	*
	17	* /dev/vcsuaN: same idea as /dev/vcsaN for unicode (not yet implemented).
	18	*
1da177e4 LT	19	* This replaces screendump and part of selection, so that the system
	20	* administrator can control access using file system permissions.
	21	*
	22	* aeb@cwi.nl - efter Friedas begravelse - 950211
	23	*
	24	* machek@k332.feld.cvut.cz - modified not to send characters to wrong console
	25	* - fixed some fatal off-by-one bugs (0-- no longer == -1 -> looping and looping and looping...)
	26	* - making it shorter - scr_readw are macros which expand in PRETTY long code
	27	*/
	28
1da177e4 LT	29	#include <linux/kernel.h>
	30	#include <linux/major.h>
	31	#include <linux/errno.h>
0e648f42	32	#include <linux/export.h>
1da177e4	33	#include <linux/tty.h>
1da177e4 LT	34	#include <linux/interrupt.h>
	35	#include <linux/mm.h>
	36	#include <linux/init.h>
	37	#include <linux/vt_kern.h>
	38	#include <linux/selection.h>
	39	#include <linux/kbd_kern.h>
	40	#include <linux/console.h>
1da177e4	41	#include <linux/device.h>
47725ac7 NP	42	#include <linux/sched.h>
	43	#include <linux/fs.h>
	44	#include <linux/poll.h>
	45	#include <linux/signal.h>
	46	#include <linux/slab.h>
	47	#include <linux/notifier.h>
c831c338	48
7c0f6ba6	49	#include <linux/uaccess.h>
1da177e4 LT	50	#include <asm/byteorder.h>
	51	#include <asm/unaligned.h>
	52
	53	#undef attr
	54	#undef org
	55	#undef addr
	56	#define HEADER_SIZE 4
	57
fcdba07e JO	58	#define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE)
fcdba07e JO	59
d21b0be2 NP	60	/*
	61	* Our minor space:
	62	*
	63	* 0 ... 63 glyph mode without attributes
	64	* 64 ... 127 unicode mode without attributes
	65	* 128 ... 191 glyph mode with attributes
	66	* 192 ... 255 unused (reserved for unicode with attributes)
	67	*
	68	* This relies on MAX_NR_CONSOLES being <= 63, meaning 63 actual consoles
	69	* with minors 0, 64, 128 and 192 being proxies for the foreground console.
	70	*/
	71	#if MAX_NR_CONSOLES > 63
	72	#warning "/dev/vcs* devices may not accommodate more than 63 consoles"
	73	#endif
	74
	75	#define console(inode) (iminor(inode) & 63)
	76	#define use_unicode(inode) (iminor(inode) & 64)
	77	#define use_attributes(inode) (iminor(inode) & 128)
	78
	79
47725ac7 NP	80	struct vcs_poll_data {
	81	struct notifier_block notifier;
	82	unsigned int cons_num;
1bf931ab	83	int event;
47725ac7 NP	84	wait_queue_head_t waitq;
	85	struct fasync_struct *fasync;
	86	};
	87
	88	static int
	89	vcs_notifier(struct notifier_block nb, unsigned long code, void _param)
	90	{
	91	struct vt_notifier_param *param = _param;
	92	struct vc_data *vc = param->vc;
	93	struct vcs_poll_data *poll =
	94	container_of(nb, struct vcs_poll_data, notifier);
	95	int currcons = poll->cons_num;
fad08b20	96	int fa_band;
47725ac7	97
fad08b20 NP	98	switch (code) {
	99	case VT_UPDATE:
	100	fa_band = POLL_PRI;
	101	break;
	102	case VT_DEALLOCATE:
	103	fa_band = POLL_HUP;
	104	break;
	105	default:
47725ac7	106	return NOTIFY_DONE;
fad08b20	107	}
47725ac7 NP	108
	109	if (currcons == 0)
	110	currcons = fg_console;
	111	else
	112	currcons--;
	113	if (currcons != vc->vc_num)
	114	return NOTIFY_DONE;
	115
1bf931ab	116	poll->event = code;
47725ac7	117	wake_up_interruptible(&poll->waitq);
fad08b20	118	kill_fasync(&poll->fasync, SIGIO, fa_band);
47725ac7 NP	119	return NOTIFY_OK;
	120	}
	121
	122	static void
	123	vcs_poll_data_free(struct vcs_poll_data *poll)
	124	{
	125	unregister_vt_notifier(&poll->notifier);
	126	kfree(poll);
	127	}
	128
	129	static struct vcs_poll_data *
	130	vcs_poll_data_get(struct file *file)
	131	{
e8cd8169	132	struct vcs_poll_data poll = file->private_data, kill = NULL;
47725ac7 NP	133
	134	if (poll)
	135	return poll;
	136
	137	poll = kzalloc(sizeof(*poll), GFP_KERNEL);
	138	if (!poll)
	139	return NULL;
d21b0be2	140	poll->cons_num = console(file_inode(file));
47725ac7 NP	141	init_waitqueue_head(&poll->waitq);
47725ac7 NP	142	poll->notifier.notifier_call = vcs_notifier;
95252f9c NP	143	/*
	144	* In order not to lose any update event, we must pretend one might
	145	* have occurred before we have a chance to register our notifier.
	146	* This is also how user space has come to detect which kernels
	147	* support POLLPRI on /dev/vcs* devices i.e. using poll() with
	148	* POLLPRI and a zero timeout.
	149	*/
	150	poll->event = VT_UPDATE;
	151
47725ac7 NP	152	if (register_vt_notifier(&poll->notifier) != 0) {
	153	kfree(poll);
	154	return NULL;
	155	}
	156
	157	/*
	158	* This code may be called either through ->poll() or ->fasync().
	159	* If we have two threads using the same file descriptor, they could
	160	* both enter this function, both notice that the structure hasn't
	161	* been allocated yet and go ahead allocating it in parallel, but
	162	* only one of them must survive and be shared otherwise we'd leak
	163	* memory with a dangling notifier callback.
	164	*/
	165	spin_lock(&file->f_lock);
	166	if (!file->private_data) {
	167	file->private_data = poll;
	168	} else {
	169	/* someone else raced ahead of us */
e8cd8169	170	kill = poll;
47725ac7 NP	171	poll = file->private_data;
	172	}
	173	spin_unlock(&file->f_lock);
e8cd8169 AV	174	if (kill)
e8cd8169 AV	175	vcs_poll_data_free(kill);
47725ac7 NP	176
	177	return poll;
	178	}
	179
fcdba07e JO	180	/*
	181	* Returns VC for inode.
	182	* Must be called with console_lock.
	183	*/
	184	static struct vc_data*
	185	vcs_vc(struct inode inode, int viewed)
	186	{
d21b0be2	187	unsigned int currcons = console(inode);
fcdba07e JO	188
	189	WARN_CONSOLE_UNLOCKED();
	190
	191	if (currcons == 0) {
	192	currcons = fg_console;
	193	if (viewed)
	194	*viewed = 1;
	195	} else {
	196	currcons--;
	197	if (viewed)
	198	*viewed = 0;
	199	}
	200	return vc_cons[currcons].d;
	201	}
	202
	203	/*
	204	* Returns size for VC carried by inode.
	205	* Must be called with console_lock.
	206	*/
1da177e4 LT	207	static int
	208	vcs_size(struct inode *inode)
	209	{
	210	int size;
1da177e4 LT	211	struct vc_data *vc;
1da177e4 LT	212
fcdba07e JO	213	WARN_CONSOLE_UNLOCKED();
	214
	215	vc = vcs_vc(inode, NULL);
	216	if (!vc)
1da177e4	217	return -ENXIO;
1da177e4 LT	218
	219	size = vc->vc_rows * vc->vc_cols;
	220
d21b0be2 NP	221	if (use_attributes(inode)) {
	222	if (use_unicode(inode))
	223	return -EOPNOTSUPP;
1da177e4	224	size = 2*size + HEADER_SIZE;
d21b0be2 NP	225	} else if (use_unicode(inode))
d21b0be2 NP	226	size *= 4;
1da177e4 LT	227	return size;
	228	}
	229
	230	static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
	231	{
	232	int size;
	233
dc1892c4	234	console_lock();
496ad9aa	235	size = vcs_size(file_inode(file));
dc1892c4	236	console_unlock();
fcdba07e	237	if (size < 0)
dc1892c4	238	return size;
65004276	239	return fixed_size_llseek(file, offset, orig, size);
1da177e4 LT	240	}
	241
	242
	243	static ssize_t
	244	vcs_read(struct file file, char __user buf, size_t count, loff_t *ppos)
	245	{
496ad9aa	246	struct inode *inode = file_inode(file);
1da177e4	247	struct vc_data *vc;
47725ac7	248	struct vcs_poll_data *poll;
d21b0be2 NP	249	long pos, read;
d21b0be2 NP	250	int attr, uni_mode, row, col, maxcol, viewed;
1da177e4 LT	251	unsigned short *org = NULL;
1da177e4 LT	252	ssize_t ret;
fcdba07e	253	char *con_buf;
1da177e4	254
fcdba07e JO	255	con_buf = (char *) __get_free_page(GFP_KERNEL);
	256	if (!con_buf)
	257	return -ENOMEM;
1da177e4 LT	258
	259	pos = *ppos;
	260
	261	/* Select the proper current console and verify
	262	* sanity of the situation under the console lock.
	263	*/
ac751efa	264	console_lock();
1da177e4	265
d21b0be2 NP	266	uni_mode = use_unicode(inode);
d21b0be2 NP	267	attr = use_attributes(inode);
1da177e4	268	ret = -ENXIO;
fcdba07e JO	269	vc = vcs_vc(inode, &viewed);
fcdba07e JO	270	if (!vc)
1da177e4	271	goto unlock_out;
1da177e4 LT	272
	273	ret = -EINVAL;
	274	if (pos < 0)
	275	goto unlock_out;
d21b0be2 NP	276	/* we enforce 32-bit alignment for pos and count in unicode mode */
	277	if (uni_mode && (pos \| count) & 3)
	278	goto unlock_out;
	279
47725ac7 NP	280	poll = file->private_data;
47725ac7 NP	281	if (count && poll)
1bf931ab	282	poll->event = 0;
1da177e4 LT	283	read = 0;
	284	ret = 0;
	285	while (count) {
	286	char con_buf0, con_buf_start;
	287	long this_round, size;
	288	ssize_t orig_count;
	289	long p = pos;
	290
	291	/* Check whether we are above size each round,
	292	* as copy_to_user at the end of this loop
	293	* could sleep.
	294	*/
	295	size = vcs_size(inode);
dc1892c4 JO	296	if (size < 0) {
	297	if (read)
	298	break;
	299	ret = size;
	300	goto unlock_out;
	301	}
1da177e4 LT	302	if (pos >= size)
	303	break;
	304	if (count > size - pos)
	305	count = size - pos;
	306
	307	this_round = count;
	308	if (this_round > CON_BUF_SIZE)
	309	this_round = CON_BUF_SIZE;
	310
	311	/* Perform the whole read into the local con_buf.
	312	* Then we can drop the console spinlock and safely
	313	* attempt to move it to userspace.
	314	*/
	315
	316	con_buf_start = con_buf0 = con_buf;
	317	orig_count = this_round;
	318	maxcol = vc->vc_cols;
d21b0be2 NP	319	if (uni_mode) {
	320	unsigned int nr;
	321
	322	ret = vc_uniscr_check(vc);
	323	if (ret)
	324	break;
	325	p /= 4;
	326	row = p / vc->vc_cols;
	327	col = p % maxcol;
	328	nr = maxcol - col;
	329	do {
	330	if (nr > this_round/4)
	331	nr = this_round/4;
708d0bff NP	332	vc_uniscr_copy_line(vc, con_buf0, viewed,
708d0bff NP	333	row, col, nr);
d21b0be2 NP	334	con_buf0 += nr * 4;
	335	this_round -= nr * 4;
	336	row++;
	337	col = 0;
	338	nr = maxcol;
	339	} while (this_round);
	340	} else if (!attr) {
1da177e4 LT	341	org = screen_pos(vc, p, viewed);
	342	col = p % maxcol;
	343	p += maxcol - col;
	344	while (this_round-- > 0) {
	345	*con_buf0++ = (vcs_scr_readw(vc, org++) & 0xff);
	346	if (++col == maxcol) {
	347	org = screen_pos(vc, p, viewed);
	348	col = 0;
	349	p += maxcol;
	350	}
	351	}
	352	} else {
	353	if (p < HEADER_SIZE) {
	354	size_t tmp_count;
	355
8a085494 NP	356	/* clamp header values if they don't fit */
	357	con_buf0[0] = min(vc->vc_rows, 0xFFu);
	358	con_buf0[1] = min(vc->vc_cols, 0xFFu);
1da177e4 LT	359	getconsxy(vc, con_buf0 + 2);
	360
	361	con_buf_start += p;
	362	this_round += p;
	363	if (this_round > CON_BUF_SIZE) {
	364	this_round = CON_BUF_SIZE;
	365	orig_count = this_round - p;
	366	}
	367
	368	tmp_count = HEADER_SIZE;
	369	if (tmp_count > this_round)
	370	tmp_count = this_round;
	371
	372	/* Advance state pointers and move on. */
	373	this_round -= tmp_count;
	374	p = HEADER_SIZE;
	375	con_buf0 = con_buf + HEADER_SIZE;
	376	/* If this_round >= 0, then p is even... */
	377	} else if (p & 1) {
	378	/* Skip first byte for output if start address is odd
	379	* Update region sizes up/down depending on free
	380	* space in buffer.
	381	*/
	382	con_buf_start++;
	383	if (this_round < CON_BUF_SIZE)
	384	this_round++;
	385	else
	386	orig_count--;
	387	}
	388	if (this_round > 0) {
	389	unsigned short tmp_buf = (unsigned short )con_buf0;
	390
	391	p -= HEADER_SIZE;
	392	p /= 2;
	393	col = p % maxcol;
	394
	395	org = screen_pos(vc, p, viewed);
	396	p += maxcol - col;
	397
	398	/* Buffer has even length, so we can always copy
	399	* character + attribute. We do not copy last byte
	400	* to userspace if this_round is odd.
	401	*/
	402	this_round = (this_round + 1) >> 1;
	403
	404	while (this_round) {
	405	*tmp_buf++ = vcs_scr_readw(vc, org++);
	406	this_round --;
	407	if (++col == maxcol) {
	408	org = screen_pos(vc, p, viewed);
	409	col = 0;
	410	p += maxcol;
	411	}
	412	}
	413	}
	414	}
	415
	416	/* Finally, release the console semaphore while we push
	417	* all the data to userspace from our temporary buffer.
	418	*
	419	* AKPM: Even though it's a semaphore, we should drop it because
	420	* the pagefault handling code may want to call printk().
	421	*/
	422
ac751efa	423	console_unlock();
1da177e4	424	ret = copy_to_user(buf, con_buf_start, orig_count);
ac751efa	425	console_lock();
1da177e4 LT	426
	427	if (ret) {
	428	read += (orig_count - ret);
	429	ret = -EFAULT;
	430	break;
	431	}
	432	buf += orig_count;
	433	pos += orig_count;
	434	read += orig_count;
	435	count -= orig_count;
	436	}
	437	*ppos += read;
	438	if (read)
	439	ret = read;
	440	unlock_out:
ac751efa	441	console_unlock();
fcdba07e	442	free_page((unsigned long) con_buf);
1da177e4 LT	443	return ret;
	444	}
	445
	446	static ssize_t
	447	vcs_write(struct file file, const char __user buf, size_t count, loff_t *ppos)
	448	{
496ad9aa	449	struct inode *inode = file_inode(file);
1da177e4 LT	450	struct vc_data *vc;
1da177e4 LT	451	long pos;
fcdba07e	452	long attr, size, written;
1da177e4	453	char *con_buf0;
fcdba07e	454	int col, maxcol, viewed;
1da177e4 LT	455	u16 org0 = NULL, org = NULL;
1da177e4 LT	456	size_t ret;
fcdba07e	457	char *con_buf;
1da177e4	458
fcdba07e JO	459	con_buf = (char *) __get_free_page(GFP_KERNEL);
	460	if (!con_buf)
	461	return -ENOMEM;
1da177e4 LT	462
	463	pos = *ppos;
	464
	465	/* Select the proper current console and verify
	466	* sanity of the situation under the console lock.
	467	*/
ac751efa	468	console_lock();
1da177e4	469
d21b0be2	470	attr = use_attributes(inode);
1da177e4	471	ret = -ENXIO;
fcdba07e JO	472	vc = vcs_vc(inode, &viewed);
fcdba07e JO	473	if (!vc)
1da177e4	474	goto unlock_out;
1da177e4 LT	475
	476	size = vcs_size(inode);
	477	ret = -EINVAL;
	478	if (pos < 0 \|\| pos > size)
	479	goto unlock_out;
	480	if (count > size - pos)
	481	count = size - pos;
	482	written = 0;
	483	while (count) {
	484	long this_round = count;
	485	size_t orig_count;
	486	long p;
	487
	488	if (this_round > CON_BUF_SIZE)
	489	this_round = CON_BUF_SIZE;
	490
	491	/* Temporarily drop the console lock so that we can read
	492	* in the write data from userspace safely.
	493	*/
ac751efa	494	console_unlock();
1da177e4	495	ret = copy_from_user(con_buf, buf, this_round);
ac751efa	496	console_lock();
1da177e4 LT	497
	498	if (ret) {
	499	this_round -= ret;
	500	if (!this_round) {
	501	/* Abort loop if no data were copied. Otherwise
	502	* fail with -EFAULT.
	503	*/
	504	if (written)
	505	break;
	506	ret = -EFAULT;
	507	goto unlock_out;
	508	}
	509	}
	510
	511	/* The vcs_size might have changed while we slept to grab
	512	* the user buffer, so recheck.
	513	* Return data written up to now on failure.
	514	*/
	515	size = vcs_size(inode);
dc1892c4 JO	516	if (size < 0) {
	517	if (written)
	518	break;
	519	ret = size;
	520	goto unlock_out;
	521	}
1da177e4 LT	522	if (pos >= size)
	523	break;
	524	if (this_round > size - pos)
	525	this_round = size - pos;
	526
	527	/* OK, now actually push the write to the console
	528	* under the lock using the local kernel buffer.
	529	*/
	530
	531	con_buf0 = con_buf;
	532	orig_count = this_round;
	533	maxcol = vc->vc_cols;
	534	p = pos;
	535	if (!attr) {
	536	org0 = org = screen_pos(vc, p, viewed);
	537	col = p % maxcol;
	538	p += maxcol - col;
	539
	540	while (this_round > 0) {
	541	unsigned char c = *con_buf0++;
	542
	543	this_round--;
	544	vcs_scr_writew(vc,
	545	(vcs_scr_readw(vc, org) & 0xff00) \| c, org);
	546	org++;
	547	if (++col == maxcol) {
	548	org = screen_pos(vc, p, viewed);
	549	col = 0;
	550	p += maxcol;
	551	}
	552	}
	553	} else {
	554	if (p < HEADER_SIZE) {
	555	char header[HEADER_SIZE];
	556
	557	getconsxy(vc, header + 2);
	558	while (p < HEADER_SIZE && this_round > 0) {
	559	this_round--;
	560	header[p++] = *con_buf0++;
	561	}
	562	if (!viewed)
	563	putconsxy(vc, header + 2);
	564	}
	565	p -= HEADER_SIZE;
	566	col = (p/2) % maxcol;
	567	if (this_round > 0) {
	568	org0 = org = screen_pos(vc, p/2, viewed);
	569	if ((p & 1) && this_round > 0) {
	570	char c;
	571
	572	this_round--;
	573	c = *con_buf0++;
	574	#ifdef __BIG_ENDIAN
	575	vcs_scr_writew(vc, c \|
	576	(vcs_scr_readw(vc, org) & 0xff00), org);
	577	#else
	578	vcs_scr_writew(vc, (c << 8) \|
	579	(vcs_scr_readw(vc, org) & 0xff), org);
	580	#endif
	581	org++;
	582	p++;
	583	if (++col == maxcol) {
	584	org = screen_pos(vc, p/2, viewed);
	585	col = 0;
586	}
587	}
588	p /= 2;
589	p += maxcol - col;
590	}
591	while (this_round > 1) {
592	unsigned short w;
593
ee025949	594	w = get_unaligned(((unsigned short *)con_buf0));
1da177e4 LT	595	vcs_scr_writew(vc, w, org++);
	596	con_buf0 += 2;
	597	this_round -= 2;
	598	if (++col == maxcol) {
	599	org = screen_pos(vc, p, viewed);
	600	col = 0;
	601	p += maxcol;
	602	}
	603	}
	604	if (this_round > 0) {
	605	unsigned char c;
	606
	607	c = *con_buf0++;
	608	#ifdef __BIG_ENDIAN
	609	vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) \| (c << 8), org);
	610	#else
	611	vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) \| c, org);
	612	#endif
	613	}
	614	}
	615	count -= orig_count;
	616	written += orig_count;
	617	buf += orig_count;
	618	pos += orig_count;
	619	if (org0)
	620	update_region(vc, (unsigned long)(org0), org - org0);
	621	}
	622	*ppos += written;
	623	ret = written;
432c9ed2 NP	624	if (written)
432c9ed2 NP	625	vcs_scr_updated(vc);
1da177e4 LT	626
1da177e4 LT	627	unlock_out:
ac751efa	628	console_unlock();
fcdba07e	629	free_page((unsigned long) con_buf);
1da177e4 LT	630	return ret;
	631	}
	632
afc9a42b	633	static __poll_t
47725ac7 NP	634	vcs_poll(struct file file, poll_table wait)
	635	{
	636	struct vcs_poll_data *poll = vcs_poll_data_get(file);
1bf931ab	637	__poll_t ret = DEFAULT_POLLMASK\|EPOLLERR;
47725ac7 NP	638
	639	if (poll) {
	640	poll_wait(file, &poll->waitq, wait);
1bf931ab NP	641	switch (poll->event) {
	642	case VT_UPDATE:
	643	ret = DEFAULT_POLLMASK\|EPOLLPRI;
	644	break;
	645	case VT_DEALLOCATE:
	646	ret = DEFAULT_POLLMASK\|EPOLLHUP\|EPOLLERR;
	647	break;
	648	case 0:
47c344d0	649	ret = DEFAULT_POLLMASK;
1bf931ab NP	650	break;
1bf931ab NP	651	}
47725ac7 NP	652	}
	653	return ret;
	654	}
	655
	656	static int
	657	vcs_fasync(int fd, struct file *file, int on)
	658	{
	659	struct vcs_poll_data *poll = file->private_data;
	660
	661	if (!poll) {
	662	/* don't allocate anything if all we want is disable fasync */
	663	if (!on)
	664	return 0;
	665	poll = vcs_poll_data_get(file);
	666	if (!poll)
	667	return -ENOMEM;
	668	}
	669
	670	return fasync_helper(fd, file, on, &poll->fasync);
	671	}
	672
1da177e4 LT	673	static int
	674	vcs_open(struct inode inode, struct file filp)
	675	{
d21b0be2 NP	676	unsigned int currcons = console(inode);
	677	bool attr = use_attributes(inode);
	678	bool uni_mode = use_unicode(inode);
f97259e3	679	int ret = 0;
d21b0be2 NP	680
	681	/* we currently don't support attributes in unicode mode */
	682	if (attr && uni_mode)
	683	return -EOPNOTSUPP;
	684
4001d7b7	685	console_lock();
1da177e4	686	if(currcons && !vc_cons_allocated(currcons-1))
f97259e3	687	ret = -ENXIO;
4001d7b7	688	console_unlock();
f97259e3	689	return ret;
1da177e4 LT	690	}
1da177e4 LT	691
47725ac7 NP	692	static int vcs_release(struct inode inode, struct file file)
	693	{
	694	struct vcs_poll_data *poll = file->private_data;
	695
	696	if (poll)
	697	vcs_poll_data_free(poll);
	698	return 0;
	699	}
	700
62322d25	701	static const struct file_operations vcs_fops = {
1da177e4 LT	702	.llseek = vcs_lseek,
	703	.read = vcs_read,
	704	.write = vcs_write,
47725ac7 NP	705	.poll = vcs_poll,
47725ac7 NP	706	.fasync = vcs_fasync,
1da177e4	707	.open = vcs_open,
47725ac7	708	.release = vcs_release,
1da177e4 LT	709	};
1da177e4 LT	710
ca8eca68	711	static struct class *vc_class;
1da177e4	712
4995f8ef	713	void vcs_make_sysfs(int index)
1da177e4	714	{
4995f8ef KS	715	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
4995f8ef KS	716	"vcs%u", index + 1);
d21b0be2 NP	717	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 65), NULL,
d21b0be2 NP	718	"vcsu%u", index + 1);
4995f8ef KS	719	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
4995f8ef KS	720	"vcsa%u", index + 1);
1da177e4	721	}
d09d7ddf	722
4995f8ef	723	void vcs_remove_sysfs(int index)
1da177e4	724	{
4995f8ef	725	device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
d21b0be2	726	device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 65));
4995f8ef	727	device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
1da177e4 LT	728	}
	729
	730	int __init vcs_init(void)
	731	{
c46a7aec KS	732	unsigned int i;
c46a7aec KS	733
1da177e4 LT	734	if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
1da177e4 LT	735	panic("unable to get major %d for vcs device", VCS_MAJOR);
ca8eca68	736	vc_class = class_create(THIS_MODULE, "vc");
1da177e4	737
03457cd4	738	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
d21b0be2	739	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 64), NULL, "vcsu");
03457cd4	740	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
c46a7aec KS	741	for (i = 0; i < MIN_NR_CONSOLES; i++)
c46a7aec KS	742	vcs_make_sysfs(i);
1da177e4 LT	743	return 0;
1da177e4 LT	744	}