[mirror_ubuntu-jammy-kernel.git] / drivers / tty / vt / vc_screen.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Provide access to virtual console memory.
 * /dev/vcs0: 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]
 *
 * 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)

struct vcs_poll_data {
	struct notifier_block notifier;
	unsigned int cons_num;
	bool seen_last_update;
	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;

	if (code != VT_UPDATE)
		return NOTIFY_DONE;

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

	poll->seen_last_update = false;
	wake_up_interruptible(&poll->waitq);
	kill_fasync(&poll->fasync, SIGIO, POLL_IN);
	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 = iminor(file_inode(file)) & 127;
	init_waitqueue_head(&poll->waitq);
	poll->notifier.notifier_call = vcs_notifier;
	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 = iminor(inode) & 127;

	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;
	int minor = iminor(inode);
	struct vc_data *vc;

	WARN_CONSOLE_UNLOCKED();

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

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

	if (minor & 128)
		size = 2*size + HEADER_SIZE;
	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);
	unsigned int currcons = iminor(inode);
	struct vc_data *vc;
	struct vcs_poll_data *poll;
	long pos;
	long attr, read;
	int 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();

	attr = (currcons & 128);
	ret = -ENXIO;
	vc = vcs_vc(inode, &viewed);
	if (!vc)
		goto unlock_out;

	ret = -EINVAL;
	if (pos < 0)
		goto unlock_out;
	poll = file->private_data;
	if (count && poll)
		poll->seen_last_update = true;
	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 (!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;

				con_buf0[0] = (char)vc->vc_rows;
				con_buf0[1] = (char)vc->vc_cols;
				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);
	unsigned int currcons = iminor(inode);
	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 = (currcons & 128);
	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|POLLERR|POLLPRI;

	if (poll) {
		poll_wait(file, &poll->waitq, wait);
		if (poll->seen_last_update)
			ret = DEFAULT_POLLMASK;
	}
	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 = iminor(inode) & 127;
	int ret = 0;
	
	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 + 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 + 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, 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 LT	3	* Provide access to virtual console memory.
	4	* /dev/vcs0: the screen as it is being viewed right now (possibly scrolled)
	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	*
	13	* This replaces screendump and part of selection, so that the system
	14	* administrator can control access using file system permissions.
	15	*
	16	* aeb@cwi.nl - efter Friedas begravelse - 950211
	17	*
	18	* machek@k332.feld.cvut.cz - modified not to send characters to wrong console
	19	* - fixed some fatal off-by-one bugs (0-- no longer == -1 -> looping and looping and looping...)
	20	* - making it shorter - scr_readw are macros which expand in PRETTY long code
	21	*/
	22
1da177e4 LT	23	#include <linux/kernel.h>
	24	#include <linux/major.h>
	25	#include <linux/errno.h>
0e648f42	26	#include <linux/export.h>
1da177e4	27	#include <linux/tty.h>
1da177e4 LT	28	#include <linux/interrupt.h>
	29	#include <linux/mm.h>
	30	#include <linux/init.h>
	31	#include <linux/vt_kern.h>
	32	#include <linux/selection.h>
	33	#include <linux/kbd_kern.h>
	34	#include <linux/console.h>
1da177e4	35	#include <linux/device.h>
47725ac7 NP	36	#include <linux/sched.h>
	37	#include <linux/fs.h>
	38	#include <linux/poll.h>
	39	#include <linux/signal.h>
	40	#include <linux/slab.h>
	41	#include <linux/notifier.h>
c831c338	42
7c0f6ba6	43	#include <linux/uaccess.h>
1da177e4 LT	44	#include <asm/byteorder.h>
	45	#include <asm/unaligned.h>
	46
	47	#undef attr
	48	#undef org
	49	#undef addr
	50	#define HEADER_SIZE 4
	51
fcdba07e JO	52	#define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE)
fcdba07e JO	53
47725ac7 NP	54	struct vcs_poll_data {
	55	struct notifier_block notifier;
	56	unsigned int cons_num;
	57	bool seen_last_update;
	58	wait_queue_head_t waitq;
	59	struct fasync_struct *fasync;
	60	};
	61
	62	static int
	63	vcs_notifier(struct notifier_block nb, unsigned long code, void _param)
	64	{
	65	struct vt_notifier_param *param = _param;
	66	struct vc_data *vc = param->vc;
	67	struct vcs_poll_data *poll =
	68	container_of(nb, struct vcs_poll_data, notifier);
	69	int currcons = poll->cons_num;
	70
	71	if (code != VT_UPDATE)
	72	return NOTIFY_DONE;
	73
	74	if (currcons == 0)
	75	currcons = fg_console;
	76	else
	77	currcons--;
	78	if (currcons != vc->vc_num)
	79	return NOTIFY_DONE;
	80
	81	poll->seen_last_update = false;
	82	wake_up_interruptible(&poll->waitq);
	83	kill_fasync(&poll->fasync, SIGIO, POLL_IN);
	84	return NOTIFY_OK;
	85	}
	86
	87	static void
	88	vcs_poll_data_free(struct vcs_poll_data *poll)
	89	{
	90	unregister_vt_notifier(&poll->notifier);
	91	kfree(poll);
	92	}
	93
	94	static struct vcs_poll_data *
	95	vcs_poll_data_get(struct file *file)
	96	{
e8cd8169	97	struct vcs_poll_data poll = file->private_data, kill = NULL;
47725ac7 NP	98
	99	if (poll)
	100	return poll;
	101
	102	poll = kzalloc(sizeof(*poll), GFP_KERNEL);
	103	if (!poll)
	104	return NULL;
496ad9aa	105	poll->cons_num = iminor(file_inode(file)) & 127;
47725ac7 NP	106	init_waitqueue_head(&poll->waitq);
	107	poll->notifier.notifier_call = vcs_notifier;
	108	if (register_vt_notifier(&poll->notifier) != 0) {
	109	kfree(poll);
	110	return NULL;
	111	}
	112
	113	/*
	114	* This code may be called either through ->poll() or ->fasync().
	115	* If we have two threads using the same file descriptor, they could
	116	* both enter this function, both notice that the structure hasn't
	117	* been allocated yet and go ahead allocating it in parallel, but
	118	* only one of them must survive and be shared otherwise we'd leak
	119	* memory with a dangling notifier callback.
	120	*/
	121	spin_lock(&file->f_lock);
	122	if (!file->private_data) {
	123	file->private_data = poll;
	124	} else {
	125	/* someone else raced ahead of us */
e8cd8169	126	kill = poll;
47725ac7 NP	127	poll = file->private_data;
	128	}
	129	spin_unlock(&file->f_lock);
e8cd8169 AV	130	if (kill)
e8cd8169 AV	131	vcs_poll_data_free(kill);
47725ac7 NP	132
	133	return poll;
	134	}
	135
fcdba07e JO	136	/*
	137	* Returns VC for inode.
	138	* Must be called with console_lock.
	139	*/
	140	static struct vc_data*
	141	vcs_vc(struct inode inode, int viewed)
	142	{
	143	unsigned int currcons = iminor(inode) & 127;
	144
	145	WARN_CONSOLE_UNLOCKED();
	146
	147	if (currcons == 0) {
	148	currcons = fg_console;
	149	if (viewed)
	150	*viewed = 1;
	151	} else {
	152	currcons--;
	153	if (viewed)
	154	*viewed = 0;
	155	}
	156	return vc_cons[currcons].d;
	157	}
	158
	159	/*
	160	* Returns size for VC carried by inode.
	161	* Must be called with console_lock.
	162	*/
1da177e4 LT	163	static int
	164	vcs_size(struct inode *inode)
	165	{
	166	int size;
	167	int minor = iminor(inode);
1da177e4 LT	168	struct vc_data *vc;
1da177e4 LT	169
fcdba07e JO	170	WARN_CONSOLE_UNLOCKED();
	171
	172	vc = vcs_vc(inode, NULL);
	173	if (!vc)
1da177e4	174	return -ENXIO;
1da177e4 LT	175
	176	size = vc->vc_rows * vc->vc_cols;
	177
	178	if (minor & 128)
	179	size = 2*size + HEADER_SIZE;
	180	return size;
	181	}
	182
	183	static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
	184	{
	185	int size;
	186
dc1892c4	187	console_lock();
496ad9aa	188	size = vcs_size(file_inode(file));
dc1892c4	189	console_unlock();
fcdba07e	190	if (size < 0)
dc1892c4	191	return size;
65004276	192	return fixed_size_llseek(file, offset, orig, size);
1da177e4 LT	193	}
	194
	195
	196	static ssize_t
	197	vcs_read(struct file file, char __user buf, size_t count, loff_t *ppos)
	198	{
496ad9aa	199	struct inode *inode = file_inode(file);
1da177e4 LT	200	unsigned int currcons = iminor(inode);
1da177e4 LT	201	struct vc_data *vc;
47725ac7	202	struct vcs_poll_data *poll;
1da177e4	203	long pos;
fcdba07e JO	204	long attr, read;
fcdba07e JO	205	int col, maxcol, viewed;
1da177e4 LT	206	unsigned short *org = NULL;
1da177e4 LT	207	ssize_t ret;
fcdba07e	208	char *con_buf;
1da177e4	209
fcdba07e JO	210	con_buf = (char *) __get_free_page(GFP_KERNEL);
	211	if (!con_buf)
	212	return -ENOMEM;
1da177e4 LT	213
	214	pos = *ppos;
	215
	216	/* Select the proper current console and verify
	217	* sanity of the situation under the console lock.
	218	*/
ac751efa	219	console_lock();
1da177e4 LT	220
1da177e4 LT	221	attr = (currcons & 128);
1da177e4	222	ret = -ENXIO;
fcdba07e JO	223	vc = vcs_vc(inode, &viewed);
fcdba07e JO	224	if (!vc)
1da177e4	225	goto unlock_out;
1da177e4 LT	226
	227	ret = -EINVAL;
	228	if (pos < 0)
	229	goto unlock_out;
47725ac7 NP	230	poll = file->private_data;
	231	if (count && poll)
	232	poll->seen_last_update = true;
1da177e4 LT	233	read = 0;
	234	ret = 0;
	235	while (count) {
	236	char con_buf0, con_buf_start;
	237	long this_round, size;
	238	ssize_t orig_count;
	239	long p = pos;
	240
	241	/* Check whether we are above size each round,
	242	* as copy_to_user at the end of this loop
	243	* could sleep.
	244	*/
	245	size = vcs_size(inode);
dc1892c4 JO	246	if (size < 0) {
	247	if (read)
	248	break;
	249	ret = size;
	250	goto unlock_out;
	251	}
1da177e4 LT	252	if (pos >= size)
	253	break;
	254	if (count > size - pos)
	255	count = size - pos;
	256
	257	this_round = count;
	258	if (this_round > CON_BUF_SIZE)
	259	this_round = CON_BUF_SIZE;
	260
	261	/* Perform the whole read into the local con_buf.
	262	* Then we can drop the console spinlock and safely
	263	* attempt to move it to userspace.
	264	*/
	265
	266	con_buf_start = con_buf0 = con_buf;
	267	orig_count = this_round;
	268	maxcol = vc->vc_cols;
	269	if (!attr) {
	270	org = screen_pos(vc, p, viewed);
	271	col = p % maxcol;
	272	p += maxcol - col;
	273	while (this_round-- > 0) {
	274	*con_buf0++ = (vcs_scr_readw(vc, org++) & 0xff);
	275	if (++col == maxcol) {
	276	org = screen_pos(vc, p, viewed);
	277	col = 0;
	278	p += maxcol;
	279	}
	280	}
	281	} else {
	282	if (p < HEADER_SIZE) {
	283	size_t tmp_count;
	284
	285	con_buf0[0] = (char)vc->vc_rows;
	286	con_buf0[1] = (char)vc->vc_cols;
	287	getconsxy(vc, con_buf0 + 2);
	288
	289	con_buf_start += p;
	290	this_round += p;
	291	if (this_round > CON_BUF_SIZE) {
	292	this_round = CON_BUF_SIZE;
	293	orig_count = this_round - p;
	294	}
	295
	296	tmp_count = HEADER_SIZE;
	297	if (tmp_count > this_round)
	298	tmp_count = this_round;
	299
	300	/* Advance state pointers and move on. */
	301	this_round -= tmp_count;
	302	p = HEADER_SIZE;
	303	con_buf0 = con_buf + HEADER_SIZE;
	304	/* If this_round >= 0, then p is even... */
	305	} else if (p & 1) {
	306	/* Skip first byte for output if start address is odd
	307	* Update region sizes up/down depending on free
	308	* space in buffer.
	309	*/
	310	con_buf_start++;
	311	if (this_round < CON_BUF_SIZE)
	312	this_round++;
	313	else
	314	orig_count--;
	315	}
316	if (this_round > 0) {
317	unsigned short tmp_buf = (unsigned short )con_buf0;
318
319	p -= HEADER_SIZE;
320	p /= 2;
321	col = p % maxcol;
322
323	org = screen_pos(vc, p, viewed);
324	p += maxcol - col;
325
326	/* Buffer has even length, so we can always copy
327	* character + attribute. We do not copy last byte
328	* to userspace if this_round is odd.
329	*/
330	this_round = (this_round + 1) >> 1;
331
332	while (this_round) {
333	*tmp_buf++ = vcs_scr_readw(vc, org++);
334	this_round --;
335	if (++col == maxcol) {
336	org = screen_pos(vc, p, viewed);
337	col = 0;
338	p += maxcol;
339	}
340	}
341	}
342	}
343
344	/* Finally, release the console semaphore while we push
345	* all the data to userspace from our temporary buffer.
346	*
347	* AKPM: Even though it's a semaphore, we should drop it because
348	* the pagefault handling code may want to call printk().
349	*/
350
ac751efa	351	console_unlock();
1da177e4	352	ret = copy_to_user(buf, con_buf_start, orig_count);
ac751efa	353	console_lock();
1da177e4 LT	354
	355	if (ret) {
	356	read += (orig_count - ret);
	357	ret = -EFAULT;
	358	break;
	359	}
	360	buf += orig_count;
	361	pos += orig_count;
	362	read += orig_count;
	363	count -= orig_count;
	364	}
	365	*ppos += read;
	366	if (read)
	367	ret = read;
	368	unlock_out:
ac751efa	369	console_unlock();
fcdba07e	370	free_page((unsigned long) con_buf);
1da177e4 LT	371	return ret;
	372	}
	373
	374	static ssize_t
	375	vcs_write(struct file file, const char __user buf, size_t count, loff_t *ppos)
	376	{
496ad9aa	377	struct inode *inode = file_inode(file);
1da177e4 LT	378	unsigned int currcons = iminor(inode);
	379	struct vc_data *vc;
	380	long pos;
fcdba07e	381	long attr, size, written;
1da177e4	382	char *con_buf0;
fcdba07e	383	int col, maxcol, viewed;
1da177e4 LT	384	u16 org0 = NULL, org = NULL;
1da177e4 LT	385	size_t ret;
fcdba07e	386	char *con_buf;
1da177e4	387
fcdba07e JO	388	con_buf = (char *) __get_free_page(GFP_KERNEL);
	389	if (!con_buf)
	390	return -ENOMEM;
1da177e4 LT	391
	392	pos = *ppos;
	393
	394	/* Select the proper current console and verify
	395	* sanity of the situation under the console lock.
	396	*/
ac751efa	397	console_lock();
1da177e4 LT	398
1da177e4 LT	399	attr = (currcons & 128);
1da177e4	400	ret = -ENXIO;
fcdba07e JO	401	vc = vcs_vc(inode, &viewed);
fcdba07e JO	402	if (!vc)
1da177e4	403	goto unlock_out;
1da177e4 LT	404
	405	size = vcs_size(inode);
	406	ret = -EINVAL;
	407	if (pos < 0 \|\| pos > size)
	408	goto unlock_out;
	409	if (count > size - pos)
	410	count = size - pos;
	411	written = 0;
	412	while (count) {
	413	long this_round = count;
	414	size_t orig_count;
	415	long p;
	416
	417	if (this_round > CON_BUF_SIZE)
	418	this_round = CON_BUF_SIZE;
	419
	420	/* Temporarily drop the console lock so that we can read
	421	* in the write data from userspace safely.
	422	*/
ac751efa	423	console_unlock();
1da177e4	424	ret = copy_from_user(con_buf, buf, this_round);
ac751efa	425	console_lock();
1da177e4 LT	426
	427	if (ret) {
	428	this_round -= ret;
	429	if (!this_round) {
	430	/* Abort loop if no data were copied. Otherwise
	431	* fail with -EFAULT.
	432	*/
	433	if (written)
	434	break;
	435	ret = -EFAULT;
	436	goto unlock_out;
	437	}
	438	}
	439
	440	/* The vcs_size might have changed while we slept to grab
	441	* the user buffer, so recheck.
	442	* Return data written up to now on failure.
	443	*/
	444	size = vcs_size(inode);
dc1892c4 JO	445	if (size < 0) {
	446	if (written)
	447	break;
	448	ret = size;
	449	goto unlock_out;
	450	}
1da177e4 LT	451	if (pos >= size)
	452	break;
	453	if (this_round > size - pos)
	454	this_round = size - pos;
	455
	456	/* OK, now actually push the write to the console
	457	* under the lock using the local kernel buffer.
	458	*/
	459
	460	con_buf0 = con_buf;
	461	orig_count = this_round;
	462	maxcol = vc->vc_cols;
	463	p = pos;
	464	if (!attr) {
	465	org0 = org = screen_pos(vc, p, viewed);
	466	col = p % maxcol;
	467	p += maxcol - col;
	468
	469	while (this_round > 0) {
	470	unsigned char c = *con_buf0++;
	471
	472	this_round--;
	473	vcs_scr_writew(vc,
	474	(vcs_scr_readw(vc, org) & 0xff00) \| c, org);
	475	org++;
	476	if (++col == maxcol) {
	477	org = screen_pos(vc, p, viewed);
	478	col = 0;
	479	p += maxcol;
	480	}
	481	}
	482	} else {
	483	if (p < HEADER_SIZE) {
	484	char header[HEADER_SIZE];
	485
	486	getconsxy(vc, header + 2);
	487	while (p < HEADER_SIZE && this_round > 0) {
	488	this_round--;
	489	header[p++] = *con_buf0++;
	490	}
	491	if (!viewed)
	492	putconsxy(vc, header + 2);
	493	}
	494	p -= HEADER_SIZE;
	495	col = (p/2) % maxcol;
	496	if (this_round > 0) {
	497	org0 = org = screen_pos(vc, p/2, viewed);
	498	if ((p & 1) && this_round > 0) {
	499	char c;
	500
	501	this_round--;
	502	c = *con_buf0++;
	503	#ifdef __BIG_ENDIAN
	504	vcs_scr_writew(vc, c \|
	505	(vcs_scr_readw(vc, org) & 0xff00), org);
	506	#else
	507	vcs_scr_writew(vc, (c << 8) \|
	508	(vcs_scr_readw(vc, org) & 0xff), org);
	509	#endif
	510	org++;
	511	p++;
	512	if (++col == maxcol) {
	513	org = screen_pos(vc, p/2, viewed);
	514	col = 0;
515	}
516	}
517	p /= 2;
518	p += maxcol - col;
519	}
520	while (this_round > 1) {
521	unsigned short w;
522
ee025949	523	w = get_unaligned(((unsigned short *)con_buf0));
1da177e4 LT	524	vcs_scr_writew(vc, w, org++);
	525	con_buf0 += 2;
	526	this_round -= 2;
	527	if (++col == maxcol) {
	528	org = screen_pos(vc, p, viewed);
	529	col = 0;
	530	p += maxcol;
	531	}
	532	}
	533	if (this_round > 0) {
	534	unsigned char c;
	535
	536	c = *con_buf0++;
	537	#ifdef __BIG_ENDIAN
	538	vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) \| (c << 8), org);
	539	#else
	540	vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) \| c, org);
	541	#endif
	542	}
	543	}
	544	count -= orig_count;
	545	written += orig_count;
	546	buf += orig_count;
	547	pos += orig_count;
	548	if (org0)
	549	update_region(vc, (unsigned long)(org0), org - org0);
	550	}
	551	*ppos += written;
	552	ret = written;
432c9ed2 NP	553	if (written)
432c9ed2 NP	554	vcs_scr_updated(vc);
1da177e4 LT	555
1da177e4 LT	556	unlock_out:
ac751efa	557	console_unlock();
fcdba07e	558	free_page((unsigned long) con_buf);
1da177e4 LT	559	return ret;
	560	}
	561
afc9a42b	562	static __poll_t
47725ac7 NP	563	vcs_poll(struct file file, poll_table wait)
	564	{
	565	struct vcs_poll_data *poll = vcs_poll_data_get(file);
afc9a42b	566	__poll_t ret = DEFAULT_POLLMASK\|POLLERR\|POLLPRI;
47725ac7 NP	567
	568	if (poll) {
	569	poll_wait(file, &poll->waitq, wait);
47c344d0 NP	570	if (poll->seen_last_update)
47c344d0 NP	571	ret = DEFAULT_POLLMASK;
47725ac7 NP	572	}
	573	return ret;
	574	}
	575
	576	static int
	577	vcs_fasync(int fd, struct file *file, int on)
	578	{
	579	struct vcs_poll_data *poll = file->private_data;
	580
	581	if (!poll) {
	582	/* don't allocate anything if all we want is disable fasync */
	583	if (!on)
	584	return 0;
	585	poll = vcs_poll_data_get(file);
	586	if (!poll)
	587	return -ENOMEM;
	588	}
	589
	590	return fasync_helper(fd, file, on, &poll->fasync);
	591	}
	592
1da177e4 LT	593	static int
	594	vcs_open(struct inode inode, struct file filp)
	595	{
	596	unsigned int currcons = iminor(inode) & 127;
f97259e3 JC	597	int ret = 0;
f97259e3 JC	598
4001d7b7	599	console_lock();
1da177e4	600	if(currcons && !vc_cons_allocated(currcons-1))
f97259e3	601	ret = -ENXIO;
4001d7b7	602	console_unlock();
f97259e3	603	return ret;
1da177e4 LT	604	}
1da177e4 LT	605
47725ac7 NP	606	static int vcs_release(struct inode inode, struct file file)
	607	{
	608	struct vcs_poll_data *poll = file->private_data;
	609
	610	if (poll)
	611	vcs_poll_data_free(poll);
	612	return 0;
	613	}
	614
62322d25	615	static const struct file_operations vcs_fops = {
1da177e4 LT	616	.llseek = vcs_lseek,
	617	.read = vcs_read,
	618	.write = vcs_write,
47725ac7 NP	619	.poll = vcs_poll,
47725ac7 NP	620	.fasync = vcs_fasync,
1da177e4	621	.open = vcs_open,
47725ac7	622	.release = vcs_release,
1da177e4 LT	623	};
1da177e4 LT	624
ca8eca68	625	static struct class *vc_class;
1da177e4	626
4995f8ef	627	void vcs_make_sysfs(int index)
1da177e4	628	{
4995f8ef KS	629	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
	630	"vcs%u", index + 1);
	631	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
	632	"vcsa%u", index + 1);
1da177e4	633	}
d09d7ddf	634
4995f8ef	635	void vcs_remove_sysfs(int index)
1da177e4	636	{
4995f8ef KS	637	device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
4995f8ef KS	638	device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
1da177e4 LT	639	}
	640
	641	int __init vcs_init(void)
	642	{
c46a7aec KS	643	unsigned int i;
c46a7aec KS	644
1da177e4 LT	645	if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
1da177e4 LT	646	panic("unable to get major %d for vcs device", VCS_MAJOR);
ca8eca68	647	vc_class = class_create(THIS_MODULE, "vc");
1da177e4	648
03457cd4 GKH	649	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
03457cd4 GKH	650	device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
c46a7aec KS	651	for (i = 0; i < MIN_NR_CONSOLES; i++)
c46a7aec KS	652	vcs_make_sysfs(i);
1da177e4 LT	653	return 0;
1da177e4 LT	654	}