1  // SPDX-License-Identifier: GPL-2.0
2  /*
3   * Provide access to virtual console memory.
4   * /dev/vcs: 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   * /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   *
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  
29  #include <linux/kernel.h>
30  #include <linux/major.h>
31  #include <linux/errno.h>
32  #include <linux/export.h>
33  #include <linux/tty.h>
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>
41  #include <linux/device.h>
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>
48  
49  #include <linux/uaccess.h>
50  #include <asm/byteorder.h>
51  #include <linux/unaligned.h>
52  
53  #define HEADER_SIZE	4u
54  #define CON_BUF_SIZE (IS_ENABLED(CONFIG_BASE_SMALL) ? 256 : PAGE_SIZE)
55  
56  /*
57   * Our minor space:
58   *
59   *   0 ... 63	glyph mode without attributes
60   *  64 ... 127	unicode mode without attributes
61   * 128 ... 191	glyph mode with attributes
62   * 192 ... 255	unused (reserved for unicode with attributes)
63   *
64   * This relies on MAX_NR_CONSOLES being  <= 63, meaning 63 actual consoles
65   * with minors 0, 64, 128 and 192 being proxies for the foreground console.
66   */
67  #if MAX_NR_CONSOLES > 63
68  #warning "/dev/vcs* devices may not accommodate more than 63 consoles"
69  #endif
70  
71  #define console(inode)		(iminor(inode) & 63)
72  #define use_unicode(inode)	(iminor(inode) & 64)
73  #define use_attributes(inode)	(iminor(inode) & 128)
74  
75  
76  struct vcs_poll_data {
77  	struct notifier_block notifier;
78  	unsigned int cons_num;
79  	int event;
80  	wait_queue_head_t waitq;
81  	struct fasync_struct *fasync;
82  };
83  
84  static int
vcs_notifier(struct notifier_block * nb,unsigned long code,void * _param)85  vcs_notifier(struct notifier_block *nb, unsigned long code, void *_param)
86  {
87  	struct vt_notifier_param *param = _param;
88  	struct vc_data *vc = param->vc;
89  	struct vcs_poll_data *poll =
90  		container_of(nb, struct vcs_poll_data, notifier);
91  	int currcons = poll->cons_num;
92  	int fa_band;
93  
94  	switch (code) {
95  	case VT_UPDATE:
96  		fa_band = POLL_PRI;
97  		break;
98  	case VT_DEALLOCATE:
99  		fa_band = POLL_HUP;
100  		break;
101  	default:
102  		return NOTIFY_DONE;
103  	}
104  
105  	if (currcons == 0)
106  		currcons = fg_console;
107  	else
108  		currcons--;
109  	if (currcons != vc->vc_num)
110  		return NOTIFY_DONE;
111  
112  	poll->event = code;
113  	wake_up_interruptible(&poll->waitq);
114  	kill_fasync(&poll->fasync, SIGIO, fa_band);
115  	return NOTIFY_OK;
116  }
117  
118  static void
vcs_poll_data_free(struct vcs_poll_data * poll)119  vcs_poll_data_free(struct vcs_poll_data *poll)
120  {
121  	unregister_vt_notifier(&poll->notifier);
122  	kfree(poll);
123  }
124  
125  static struct vcs_poll_data *
vcs_poll_data_get(struct file * file)126  vcs_poll_data_get(struct file *file)
127  {
128  	struct vcs_poll_data *poll = file->private_data, *kill = NULL;
129  
130  	if (poll)
131  		return poll;
132  
133  	poll = kzalloc(sizeof(*poll), GFP_KERNEL);
134  	if (!poll)
135  		return NULL;
136  	poll->cons_num = console(file_inode(file));
137  	init_waitqueue_head(&poll->waitq);
138  	poll->notifier.notifier_call = vcs_notifier;
139  	/*
140  	 * In order not to lose any update event, we must pretend one might
141  	 * have occurred before we have a chance to register our notifier.
142  	 * This is also how user space has come to detect which kernels
143  	 * support POLLPRI on /dev/vcs* devices i.e. using poll() with
144  	 * POLLPRI and a zero timeout.
145  	 */
146  	poll->event = VT_UPDATE;
147  
148  	if (register_vt_notifier(&poll->notifier) != 0) {
149  		kfree(poll);
150  		return NULL;
151  	}
152  
153  	/*
154  	 * This code may be called either through ->poll() or ->fasync().
155  	 * If we have two threads using the same file descriptor, they could
156  	 * both enter this function, both notice that the structure hasn't
157  	 * been allocated yet and go ahead allocating it in parallel, but
158  	 * only one of them must survive and be shared otherwise we'd leak
159  	 * memory with a dangling notifier callback.
160  	 */
161  	spin_lock(&file->f_lock);
162  	if (!file->private_data) {
163  		file->private_data = poll;
164  	} else {
165  		/* someone else raced ahead of us */
166  		kill = poll;
167  		poll = file->private_data;
168  	}
169  	spin_unlock(&file->f_lock);
170  	if (kill)
171  		vcs_poll_data_free(kill);
172  
173  	return poll;
174  }
175  
176  /**
177   * vcs_vc - return VC for @inode
178   * @inode: inode for which to return a VC
179   * @viewed: returns whether this console is currently foreground (viewed)
180   *
181   * Must be called with console_lock.
182   */
vcs_vc(struct inode * inode,bool * viewed)183  static struct vc_data *vcs_vc(struct inode *inode, bool *viewed)
184  {
185  	unsigned int currcons = console(inode);
186  
187  	WARN_CONSOLE_UNLOCKED();
188  
189  	if (currcons == 0) {
190  		currcons = fg_console;
191  		if (viewed)
192  			*viewed = true;
193  	} else {
194  		currcons--;
195  		if (viewed)
196  			*viewed = false;
197  	}
198  	return vc_cons[currcons].d;
199  }
200  
201  /**
202   * vcs_size - return size for a VC in @vc
203   * @vc: which VC
204   * @attr: does it use attributes?
205   * @unicode: is it unicode?
206   *
207   * Must be called with console_lock.
208   */
vcs_size(const struct vc_data * vc,bool attr,bool unicode)209  static int vcs_size(const struct vc_data *vc, bool attr, bool unicode)
210  {
211  	int size;
212  
213  	WARN_CONSOLE_UNLOCKED();
214  
215  	size = vc->vc_rows * vc->vc_cols;
216  
217  	if (attr) {
218  		if (unicode)
219  			return -EOPNOTSUPP;
220  
221  		size = 2 * size + HEADER_SIZE;
222  	} else if (unicode)
223  		size *= 4;
224  
225  	return size;
226  }
227  
vcs_lseek(struct file * file,loff_t offset,int orig)228  static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
229  {
230  	struct inode *inode = file_inode(file);
231  	struct vc_data *vc;
232  	int size;
233  
234  	console_lock();
235  	vc = vcs_vc(inode, NULL);
236  	if (!vc) {
237  		console_unlock();
238  		return -ENXIO;
239  	}
240  
241  	size = vcs_size(vc, use_attributes(inode), use_unicode(inode));
242  	console_unlock();
243  	if (size < 0)
244  		return size;
245  	return fixed_size_llseek(file, offset, orig, size);
246  }
247  
vcs_read_buf_uni(struct vc_data * vc,char * con_buf,unsigned int pos,unsigned int count,bool viewed)248  static int vcs_read_buf_uni(struct vc_data *vc, char *con_buf,
249  		unsigned int pos, unsigned int count, bool viewed)
250  {
251  	unsigned int nr, row, col, maxcol = vc->vc_cols;
252  	int ret;
253  
254  	ret = vc_uniscr_check(vc);
255  	if (ret)
256  		return ret;
257  
258  	pos /= 4;
259  	row = pos / maxcol;
260  	col = pos % maxcol;
261  	nr = maxcol - col;
262  	do {
263  		if (nr > count / 4)
264  			nr = count / 4;
265  		vc_uniscr_copy_line(vc, con_buf, viewed, row, col, nr);
266  		con_buf += nr * 4;
267  		count -= nr * 4;
268  		row++;
269  		col = 0;
270  		nr = maxcol;
271  	} while (count);
272  
273  	return 0;
274  }
275  
vcs_read_buf_noattr(const struct vc_data * vc,char * con_buf,unsigned int pos,unsigned int count,bool viewed)276  static void vcs_read_buf_noattr(const struct vc_data *vc, char *con_buf,
277  		unsigned int pos, unsigned int count, bool viewed)
278  {
279  	u16 *org;
280  	unsigned int col, maxcol = vc->vc_cols;
281  
282  	org = screen_pos(vc, pos, viewed);
283  	col = pos % maxcol;
284  	pos += maxcol - col;
285  
286  	while (count-- > 0) {
287  		*con_buf++ = (vcs_scr_readw(vc, org++) & 0xff);
288  		if (++col == maxcol) {
289  			org = screen_pos(vc, pos, viewed);
290  			col = 0;
291  			pos += maxcol;
292  		}
293  	}
294  }
295  
vcs_read_buf(const struct vc_data * vc,char * con_buf,unsigned int pos,unsigned int count,bool viewed,unsigned int * skip)296  static unsigned int vcs_read_buf(const struct vc_data *vc, char *con_buf,
297  		unsigned int pos, unsigned int count, bool viewed,
298  		unsigned int *skip)
299  {
300  	u16 *org, *con_buf16;
301  	unsigned int col, maxcol = vc->vc_cols;
302  	unsigned int filled = count;
303  
304  	if (pos < HEADER_SIZE) {
305  		/* clamp header values if they don't fit */
306  		con_buf[0] = min(vc->vc_rows, 0xFFu);
307  		con_buf[1] = min(vc->vc_cols, 0xFFu);
308  		getconsxy(vc, con_buf + 2);
309  
310  		*skip += pos;
311  		count += pos;
312  		if (count > CON_BUF_SIZE) {
313  			count = CON_BUF_SIZE;
314  			filled = count - pos;
315  		}
316  
317  		/* Advance state pointers and move on. */
318  		count -= min(HEADER_SIZE, count);
319  		pos = HEADER_SIZE;
320  		con_buf += HEADER_SIZE;
321  		/* If count >= 0, then pos is even... */
322  	} else if (pos & 1) {
323  		/*
324  		 * Skip first byte for output if start address is odd. Update
325  		 * region sizes up/down depending on free space in buffer.
326  		 */
327  		(*skip)++;
328  		if (count < CON_BUF_SIZE)
329  			count++;
330  		else
331  			filled--;
332  	}
333  
334  	if (!count)
335  		return filled;
336  
337  	pos -= HEADER_SIZE;
338  	pos /= 2;
339  	col = pos % maxcol;
340  
341  	org = screen_pos(vc, pos, viewed);
342  	pos += maxcol - col;
343  
344  	/*
345  	 * Buffer has even length, so we can always copy character + attribute.
346  	 * We do not copy last byte to userspace if count is odd.
347  	 */
348  	count = (count + 1) / 2;
349  	con_buf16 = (u16 *)con_buf;
350  
351  	while (count) {
352  		*con_buf16++ = vcs_scr_readw(vc, org++);
353  		count--;
354  		if (++col == maxcol) {
355  			org = screen_pos(vc, pos, viewed);
356  			col = 0;
357  			pos += maxcol;
358  		}
359  	}
360  
361  	return filled;
362  }
363  
364  static ssize_t
vcs_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)365  vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
366  {
367  	struct inode *inode = file_inode(file);
368  	struct vc_data *vc;
369  	struct vcs_poll_data *poll;
370  	unsigned int read;
371  	ssize_t ret;
372  	char *con_buf;
373  	loff_t pos;
374  	bool viewed, attr, uni_mode;
375  
376  	con_buf = (char *) __get_free_page(GFP_KERNEL);
377  	if (!con_buf)
378  		return -ENOMEM;
379  
380  	pos = *ppos;
381  
382  	/* Select the proper current console and verify
383  	 * sanity of the situation under the console lock.
384  	 */
385  	console_lock();
386  
387  	uni_mode = use_unicode(inode);
388  	attr = use_attributes(inode);
389  
390  	ret = -EINVAL;
391  	if (pos < 0)
392  		goto unlock_out;
393  	/* we enforce 32-bit alignment for pos and count in unicode mode */
394  	if (uni_mode && (pos | count) & 3)
395  		goto unlock_out;
396  
397  	poll = file->private_data;
398  	if (count && poll)
399  		poll->event = 0;
400  	read = 0;
401  	ret = 0;
402  	while (count) {
403  		unsigned int this_round, skip = 0;
404  		int size;
405  
406  		vc = vcs_vc(inode, &viewed);
407  		if (!vc) {
408  			ret = -ENXIO;
409  			break;
410  		}
411  
412  		/* Check whether we are above size each round,
413  		 * as copy_to_user at the end of this loop
414  		 * could sleep.
415  		 */
416  		size = vcs_size(vc, attr, uni_mode);
417  		if (size < 0) {
418  			ret = size;
419  			break;
420  		}
421  		if (pos >= size)
422  			break;
423  		if (count > size - pos)
424  			count = size - pos;
425  
426  		this_round = count;
427  		if (this_round > CON_BUF_SIZE)
428  			this_round = CON_BUF_SIZE;
429  
430  		/* Perform the whole read into the local con_buf.
431  		 * Then we can drop the console spinlock and safely
432  		 * attempt to move it to userspace.
433  		 */
434  
435  		if (uni_mode) {
436  			ret = vcs_read_buf_uni(vc, con_buf, pos, this_round,
437  					viewed);
438  			if (ret)
439  				break;
440  		} else if (!attr) {
441  			vcs_read_buf_noattr(vc, con_buf, pos, this_round,
442  					viewed);
443  		} else {
444  			this_round = vcs_read_buf(vc, con_buf, pos, this_round,
445  					viewed, &skip);
446  		}
447  
448  		/* Finally, release the console semaphore while we push
449  		 * all the data to userspace from our temporary buffer.
450  		 *
451  		 * AKPM: Even though it's a semaphore, we should drop it because
452  		 * the pagefault handling code may want to call printk().
453  		 */
454  
455  		console_unlock();
456  		ret = copy_to_user(buf, con_buf + skip, this_round);
457  		console_lock();
458  
459  		if (ret) {
460  			read += this_round - ret;
461  			ret = -EFAULT;
462  			break;
463  		}
464  		buf += this_round;
465  		pos += this_round;
466  		read += this_round;
467  		count -= this_round;
468  	}
469  	*ppos += read;
470  	if (read)
471  		ret = read;
472  unlock_out:
473  	console_unlock();
474  	free_page((unsigned long) con_buf);
475  	return ret;
476  }
477  
vcs_write_buf_noattr(struct vc_data * vc,const char * con_buf,unsigned int pos,unsigned int count,bool viewed,u16 ** org0)478  static u16 *vcs_write_buf_noattr(struct vc_data *vc, const char *con_buf,
479  		unsigned int pos, unsigned int count, bool viewed, u16 **org0)
480  {
481  	u16 *org;
482  	unsigned int col, maxcol = vc->vc_cols;
483  
484  	*org0 = org = screen_pos(vc, pos, viewed);
485  	col = pos % maxcol;
486  	pos += maxcol - col;
487  
488  	while (count > 0) {
489  		unsigned char c = *con_buf++;
490  
491  		count--;
492  		vcs_scr_writew(vc,
493  			       (vcs_scr_readw(vc, org) & 0xff00) | c, org);
494  		org++;
495  		if (++col == maxcol) {
496  			org = screen_pos(vc, pos, viewed);
497  			col = 0;
498  			pos += maxcol;
499  		}
500  	}
501  
502  	return org;
503  }
504  
505  /*
506   * Compilers (gcc 10) are unable to optimize the swap in cpu_to_le16. So do it
507   * the poor man way.
508   */
vc_compile_le16(u8 hi,u8 lo)509  static inline u16 vc_compile_le16(u8 hi, u8 lo)
510  {
511  #ifdef __BIG_ENDIAN
512  	return (lo << 8u) | hi;
513  #else
514  	return (hi << 8u) | lo;
515  #endif
516  }
517  
vcs_write_buf(struct vc_data * vc,const char * con_buf,unsigned int pos,unsigned int count,bool viewed,u16 ** org0)518  static u16 *vcs_write_buf(struct vc_data *vc, const char *con_buf,
519  		unsigned int pos, unsigned int count, bool viewed, u16 **org0)
520  {
521  	u16 *org;
522  	unsigned int col, maxcol = vc->vc_cols;
523  	unsigned char c;
524  
525  	/* header */
526  	if (pos < HEADER_SIZE) {
527  		char header[HEADER_SIZE];
528  
529  		getconsxy(vc, header + 2);
530  		while (pos < HEADER_SIZE && count > 0) {
531  			count--;
532  			header[pos++] = *con_buf++;
533  		}
534  		if (!viewed)
535  			putconsxy(vc, header + 2);
536  	}
537  
538  	if (!count)
539  		return NULL;
540  
541  	pos -= HEADER_SIZE;
542  	col = (pos/2) % maxcol;
543  
544  	*org0 = org = screen_pos(vc, pos/2, viewed);
545  
546  	/* odd pos -- the first single character */
547  	if (pos & 1) {
548  		count--;
549  		c = *con_buf++;
550  		vcs_scr_writew(vc, vc_compile_le16(c, vcs_scr_readw(vc, org)),
551  				org);
552  		org++;
553  		pos++;
554  		if (++col == maxcol) {
555  			org = screen_pos(vc, pos/2, viewed);
556  			col = 0;
557  		}
558  	}
559  
560  	pos /= 2;
561  	pos += maxcol - col;
562  
563  	/* even pos -- handle attr+character pairs */
564  	while (count > 1) {
565  		unsigned short w;
566  
567  		w = get_unaligned(((unsigned short *)con_buf));
568  		vcs_scr_writew(vc, w, org++);
569  		con_buf += 2;
570  		count -= 2;
571  		if (++col == maxcol) {
572  			org = screen_pos(vc, pos, viewed);
573  			col = 0;
574  			pos += maxcol;
575  		}
576  	}
577  
578  	if (!count)
579  		return org;
580  
581  	/* odd pos -- the remaining character */
582  	c = *con_buf++;
583  	vcs_scr_writew(vc, vc_compile_le16(vcs_scr_readw(vc, org) >> 8, c),
584  				org);
585  
586  	return org;
587  }
588  
589  static ssize_t
vcs_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)590  vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
591  {
592  	struct inode *inode = file_inode(file);
593  	struct vc_data *vc;
594  	char *con_buf;
595  	u16 *org0, *org;
596  	unsigned int written;
597  	int size;
598  	ssize_t ret;
599  	loff_t pos;
600  	bool viewed, attr;
601  
602  	if (use_unicode(inode))
603  		return -EOPNOTSUPP;
604  
605  	con_buf = (char *) __get_free_page(GFP_KERNEL);
606  	if (!con_buf)
607  		return -ENOMEM;
608  
609  	pos = *ppos;
610  
611  	/* Select the proper current console and verify
612  	 * sanity of the situation under the console lock.
613  	 */
614  	console_lock();
615  
616  	attr = use_attributes(inode);
617  	ret = -ENXIO;
618  	vc = vcs_vc(inode, &viewed);
619  	if (!vc)
620  		goto unlock_out;
621  
622  	size = vcs_size(vc, attr, false);
623  	if (size < 0) {
624  		ret = size;
625  		goto unlock_out;
626  	}
627  	ret = -EINVAL;
628  	if (pos < 0 || pos > size)
629  		goto unlock_out;
630  	if (count > size - pos)
631  		count = size - pos;
632  	written = 0;
633  	while (count) {
634  		unsigned int this_round = count;
635  
636  		if (this_round > CON_BUF_SIZE)
637  			this_round = CON_BUF_SIZE;
638  
639  		/* Temporarily drop the console lock so that we can read
640  		 * in the write data from userspace safely.
641  		 */
642  		console_unlock();
643  		ret = copy_from_user(con_buf, buf, this_round);
644  		console_lock();
645  
646  		if (ret) {
647  			this_round -= ret;
648  			if (!this_round) {
649  				/* Abort loop if no data were copied. Otherwise
650  				 * fail with -EFAULT.
651  				 */
652  				if (written)
653  					break;
654  				ret = -EFAULT;
655  				goto unlock_out;
656  			}
657  		}
658  
659  		/* The vc might have been freed or vcs_size might have changed
660  		 * while we slept to grab the user buffer, so recheck.
661  		 * Return data written up to now on failure.
662  		 */
663  		vc = vcs_vc(inode, &viewed);
664  		if (!vc) {
665  			if (written)
666  				break;
667  			ret = -ENXIO;
668  			goto unlock_out;
669  		}
670  		size = vcs_size(vc, attr, false);
671  		if (size < 0) {
672  			if (written)
673  				break;
674  			ret = size;
675  			goto unlock_out;
676  		}
677  		if (pos >= size)
678  			break;
679  		if (this_round > size - pos)
680  			this_round = size - pos;
681  
682  		/* OK, now actually push the write to the console
683  		 * under the lock using the local kernel buffer.
684  		 */
685  
686  		if (attr)
687  			org = vcs_write_buf(vc, con_buf, pos, this_round,
688  					viewed, &org0);
689  		else
690  			org = vcs_write_buf_noattr(vc, con_buf, pos, this_round,
691  					viewed, &org0);
692  
693  		count -= this_round;
694  		written += this_round;
695  		buf += this_round;
696  		pos += this_round;
697  		if (org)
698  			update_region(vc, (unsigned long)(org0), org - org0);
699  	}
700  	*ppos += written;
701  	ret = written;
702  	if (written)
703  		vcs_scr_updated(vc);
704  
705  unlock_out:
706  	console_unlock();
707  	free_page((unsigned long) con_buf);
708  	return ret;
709  }
710  
711  static __poll_t
vcs_poll(struct file * file,poll_table * wait)712  vcs_poll(struct file *file, poll_table *wait)
713  {
714  	struct vcs_poll_data *poll = vcs_poll_data_get(file);
715  	__poll_t ret = DEFAULT_POLLMASK|EPOLLERR;
716  
717  	if (poll) {
718  		poll_wait(file, &poll->waitq, wait);
719  		switch (poll->event) {
720  		case VT_UPDATE:
721  			ret = DEFAULT_POLLMASK|EPOLLPRI;
722  			break;
723  		case VT_DEALLOCATE:
724  			ret = DEFAULT_POLLMASK|EPOLLHUP|EPOLLERR;
725  			break;
726  		case 0:
727  			ret = DEFAULT_POLLMASK;
728  			break;
729  		}
730  	}
731  	return ret;
732  }
733  
734  static int
vcs_fasync(int fd,struct file * file,int on)735  vcs_fasync(int fd, struct file *file, int on)
736  {
737  	struct vcs_poll_data *poll = file->private_data;
738  
739  	if (!poll) {
740  		/* don't allocate anything if all we want is disable fasync */
741  		if (!on)
742  			return 0;
743  		poll = vcs_poll_data_get(file);
744  		if (!poll)
745  			return -ENOMEM;
746  	}
747  
748  	return fasync_helper(fd, file, on, &poll->fasync);
749  }
750  
751  static int
vcs_open(struct inode * inode,struct file * filp)752  vcs_open(struct inode *inode, struct file *filp)
753  {
754  	unsigned int currcons = console(inode);
755  	bool attr = use_attributes(inode);
756  	bool uni_mode = use_unicode(inode);
757  	int ret = 0;
758  
759  	/* we currently don't support attributes in unicode mode */
760  	if (attr && uni_mode)
761  		return -EOPNOTSUPP;
762  
763  	console_lock();
764  	if(currcons && !vc_cons_allocated(currcons-1))
765  		ret = -ENXIO;
766  	console_unlock();
767  	return ret;
768  }
769  
vcs_release(struct inode * inode,struct file * file)770  static int vcs_release(struct inode *inode, struct file *file)
771  {
772  	struct vcs_poll_data *poll = file->private_data;
773  
774  	if (poll)
775  		vcs_poll_data_free(poll);
776  	return 0;
777  }
778  
779  static const struct file_operations vcs_fops = {
780  	.llseek		= vcs_lseek,
781  	.read		= vcs_read,
782  	.write		= vcs_write,
783  	.poll		= vcs_poll,
784  	.fasync		= vcs_fasync,
785  	.open		= vcs_open,
786  	.release	= vcs_release,
787  };
788  
789  static const struct class vc_class = {
790  	.name = "vc",
791  };
792  
vcs_make_sysfs(int index)793  void vcs_make_sysfs(int index)
794  {
795  	device_create(&vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL, "vcs%u", index + 1);
796  	device_create(&vc_class, NULL, MKDEV(VCS_MAJOR, index + 65), NULL, "vcsu%u", index + 1);
797  	device_create(&vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL, "vcsa%u", index + 1);
798  }
799  
vcs_remove_sysfs(int index)800  void vcs_remove_sysfs(int index)
801  {
802  	device_destroy(&vc_class, MKDEV(VCS_MAJOR, index + 1));
803  	device_destroy(&vc_class, MKDEV(VCS_MAJOR, index + 65));
804  	device_destroy(&vc_class, MKDEV(VCS_MAJOR, index + 129));
805  }
806  
vcs_init(void)807  int __init vcs_init(void)
808  {
809  	unsigned int i;
810  
811  	if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
812  		panic("unable to get major %d for vcs device", VCS_MAJOR);
813  	if (class_register(&vc_class))
814  		panic("unable to create vc_class");
815  
816  	device_create(&vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
817  	device_create(&vc_class, NULL, MKDEV(VCS_MAJOR, 64), NULL, "vcsu");
818  	device_create(&vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
819  	for (i = 0; i < MIN_NR_CONSOLES; i++)
820  		vcs_make_sysfs(i);
821  	return 0;
822  }
823