blob: 273ab44cc91d7510e4e779da98c5e13ebbbbe867 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/drivers/char/vc_screen.c
3 *
4 * Provide access to virtual console memory.
5 * /dev/vcs0: the screen as it is being viewed right now (possibly scrolled)
6 * /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63)
7 * [minor: N]
8 *
9 * /dev/vcsaN: idem, but including attributes, and prefixed with
10 * the 4 bytes lines,columns,x,y (as screendump used to give).
11 * Attribute/character pair is in native endianity.
12 * [minor: N+128]
13 *
14 * This replaces screendump and part of selection, so that the system
15 * administrator can control access using file system permissions.
16 *
17 * aeb@cwi.nl - efter Friedas begravelse - 950211
18 *
19 * machek@k332.feld.cvut.cz - modified not to send characters to wrong console
20 * - fixed some fatal off-by-one bugs (0-- no longer == -1 -> looping and looping and looping...)
21 * - making it shorter - scr_readw are macros which expand in PRETTY long code
22 */
23
Linus Torvalds1da177e2005-04-16 15:20:36 -070024#include <linux/kernel.h>
25#include <linux/major.h>
26#include <linux/errno.h>
27#include <linux/tty.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070028#include <linux/interrupt.h>
29#include <linux/mm.h>
30#include <linux/init.h>
Matthias Kaehlckec831c332007-05-08 00:39:49 -070031#include <linux/mutex.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070032#include <linux/vt_kern.h>
33#include <linux/selection.h>
34#include <linux/kbd_kern.h>
35#include <linux/console.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070036#include <linux/device.h>
Jonathan Corbetf97259e2008-05-16 13:47:50 -060037#include <linux/smp_lock.h>
Nicolas Pitre47725ac2010-10-05 14:22:37 -040038#include <linux/sched.h>
39#include <linux/fs.h>
40#include <linux/poll.h>
41#include <linux/signal.h>
42#include <linux/slab.h>
43#include <linux/notifier.h>
Matthias Kaehlckec831c332007-05-08 00:39:49 -070044
Linus Torvalds1da177e2005-04-16 15:20:36 -070045#include <asm/uaccess.h>
46#include <asm/byteorder.h>
47#include <asm/unaligned.h>
48
49#undef attr
50#undef org
51#undef addr
52#define HEADER_SIZE 4
53
Nicolas Pitre47725ac2010-10-05 14:22:37 -040054struct 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
62static int
63vcs_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
87static void
88vcs_poll_data_free(struct vcs_poll_data *poll)
89{
90 unregister_vt_notifier(&poll->notifier);
91 kfree(poll);
92}
93
94static struct vcs_poll_data *
95vcs_poll_data_get(struct file *file)
96{
97 struct vcs_poll_data *poll = file->private_data;
98
99 if (poll)
100 return poll;
101
102 poll = kzalloc(sizeof(*poll), GFP_KERNEL);
103 if (!poll)
104 return NULL;
105 poll->cons_num = iminor(file->f_path.dentry->d_inode) & 127;
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 */
126 vcs_poll_data_free(poll);
127 poll = file->private_data;
128 }
129 spin_unlock(&file->f_lock);
130
131 return poll;
132}
133
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134static int
135vcs_size(struct inode *inode)
136{
137 int size;
138 int minor = iminor(inode);
139 int currcons = minor & 127;
140 struct vc_data *vc;
141
142 if (currcons == 0)
143 currcons = fg_console;
144 else
145 currcons--;
146 if (!vc_cons_allocated(currcons))
147 return -ENXIO;
148 vc = vc_cons[currcons].d;
149
150 size = vc->vc_rows * vc->vc_cols;
151
152 if (minor & 128)
153 size = 2*size + HEADER_SIZE;
154 return size;
155}
156
157static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
158{
159 int size;
160
Matthias Kaehlckec831c332007-05-08 00:39:49 -0700161 mutex_lock(&con_buf_mtx);
Josef Sipeka7113a92006-12-08 02:36:55 -0800162 size = vcs_size(file->f_path.dentry->d_inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 switch (orig) {
164 default:
Matthias Kaehlckec831c332007-05-08 00:39:49 -0700165 mutex_unlock(&con_buf_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 return -EINVAL;
167 case 2:
168 offset += size;
169 break;
170 case 1:
171 offset += file->f_pos;
172 case 0:
173 break;
174 }
175 if (offset < 0 || offset > size) {
Matthias Kaehlckec831c332007-05-08 00:39:49 -0700176 mutex_unlock(&con_buf_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177 return -EINVAL;
178 }
179 file->f_pos = offset;
Matthias Kaehlckec831c332007-05-08 00:39:49 -0700180 mutex_unlock(&con_buf_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 return file->f_pos;
182}
183
184
185static ssize_t
186vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
187{
Josef Sipeka7113a92006-12-08 02:36:55 -0800188 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 unsigned int currcons = iminor(inode);
190 struct vc_data *vc;
Nicolas Pitre47725ac2010-10-05 14:22:37 -0400191 struct vcs_poll_data *poll;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 long pos;
193 long viewed, attr, read;
194 int col, maxcol;
195 unsigned short *org = NULL;
196 ssize_t ret;
197
Matthias Kaehlckec831c332007-05-08 00:39:49 -0700198 mutex_lock(&con_buf_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199
200 pos = *ppos;
201
202 /* Select the proper current console and verify
203 * sanity of the situation under the console lock.
204 */
205 acquire_console_sem();
206
207 attr = (currcons & 128);
208 currcons = (currcons & 127);
209 if (currcons == 0) {
210 currcons = fg_console;
211 viewed = 1;
212 } else {
213 currcons--;
214 viewed = 0;
215 }
216 ret = -ENXIO;
217 if (!vc_cons_allocated(currcons))
218 goto unlock_out;
219 vc = vc_cons[currcons].d;
220
221 ret = -EINVAL;
222 if (pos < 0)
223 goto unlock_out;
Nicolas Pitre47725ac2010-10-05 14:22:37 -0400224 poll = file->private_data;
225 if (count && poll)
226 poll->seen_last_update = true;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 read = 0;
228 ret = 0;
229 while (count) {
230 char *con_buf0, *con_buf_start;
231 long this_round, size;
232 ssize_t orig_count;
233 long p = pos;
234
235 /* Check whether we are above size each round,
236 * as copy_to_user at the end of this loop
237 * could sleep.
238 */
239 size = vcs_size(inode);
240 if (pos >= size)
241 break;
242 if (count > size - pos)
243 count = size - pos;
244
245 this_round = count;
246 if (this_round > CON_BUF_SIZE)
247 this_round = CON_BUF_SIZE;
248
249 /* Perform the whole read into the local con_buf.
250 * Then we can drop the console spinlock and safely
251 * attempt to move it to userspace.
252 */
253
254 con_buf_start = con_buf0 = con_buf;
255 orig_count = this_round;
256 maxcol = vc->vc_cols;
257 if (!attr) {
258 org = screen_pos(vc, p, viewed);
259 col = p % maxcol;
260 p += maxcol - col;
261 while (this_round-- > 0) {
262 *con_buf0++ = (vcs_scr_readw(vc, org++) & 0xff);
263 if (++col == maxcol) {
264 org = screen_pos(vc, p, viewed);
265 col = 0;
266 p += maxcol;
267 }
268 }
269 } else {
270 if (p < HEADER_SIZE) {
271 size_t tmp_count;
272
273 con_buf0[0] = (char)vc->vc_rows;
274 con_buf0[1] = (char)vc->vc_cols;
275 getconsxy(vc, con_buf0 + 2);
276
277 con_buf_start += p;
278 this_round += p;
279 if (this_round > CON_BUF_SIZE) {
280 this_round = CON_BUF_SIZE;
281 orig_count = this_round - p;
282 }
283
284 tmp_count = HEADER_SIZE;
285 if (tmp_count > this_round)
286 tmp_count = this_round;
287
288 /* Advance state pointers and move on. */
289 this_round -= tmp_count;
290 p = HEADER_SIZE;
291 con_buf0 = con_buf + HEADER_SIZE;
292 /* If this_round >= 0, then p is even... */
293 } else if (p & 1) {
294 /* Skip first byte for output if start address is odd
295 * Update region sizes up/down depending on free
296 * space in buffer.
297 */
298 con_buf_start++;
299 if (this_round < CON_BUF_SIZE)
300 this_round++;
301 else
302 orig_count--;
303 }
304 if (this_round > 0) {
305 unsigned short *tmp_buf = (unsigned short *)con_buf0;
306
307 p -= HEADER_SIZE;
308 p /= 2;
309 col = p % maxcol;
310
311 org = screen_pos(vc, p, viewed);
312 p += maxcol - col;
313
314 /* Buffer has even length, so we can always copy
315 * character + attribute. We do not copy last byte
316 * to userspace if this_round is odd.
317 */
318 this_round = (this_round + 1) >> 1;
319
320 while (this_round) {
321 *tmp_buf++ = vcs_scr_readw(vc, org++);
322 this_round --;
323 if (++col == maxcol) {
324 org = screen_pos(vc, p, viewed);
325 col = 0;
326 p += maxcol;
327 }
328 }
329 }
330 }
331
332 /* Finally, release the console semaphore while we push
333 * all the data to userspace from our temporary buffer.
334 *
335 * AKPM: Even though it's a semaphore, we should drop it because
336 * the pagefault handling code may want to call printk().
337 */
338
339 release_console_sem();
340 ret = copy_to_user(buf, con_buf_start, orig_count);
341 acquire_console_sem();
342
343 if (ret) {
344 read += (orig_count - ret);
345 ret = -EFAULT;
346 break;
347 }
348 buf += orig_count;
349 pos += orig_count;
350 read += orig_count;
351 count -= orig_count;
352 }
353 *ppos += read;
354 if (read)
355 ret = read;
356unlock_out:
357 release_console_sem();
Matthias Kaehlckec831c332007-05-08 00:39:49 -0700358 mutex_unlock(&con_buf_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 return ret;
360}
361
362static ssize_t
363vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
364{
Josef Sipeka7113a92006-12-08 02:36:55 -0800365 struct inode *inode = file->f_path.dentry->d_inode;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700366 unsigned int currcons = iminor(inode);
367 struct vc_data *vc;
368 long pos;
369 long viewed, attr, size, written;
370 char *con_buf0;
371 int col, maxcol;
372 u16 *org0 = NULL, *org = NULL;
373 size_t ret;
374
Matthias Kaehlckec831c332007-05-08 00:39:49 -0700375 mutex_lock(&con_buf_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376
377 pos = *ppos;
378
379 /* Select the proper current console and verify
380 * sanity of the situation under the console lock.
381 */
382 acquire_console_sem();
383
384 attr = (currcons & 128);
385 currcons = (currcons & 127);
386
387 if (currcons == 0) {
388 currcons = fg_console;
389 viewed = 1;
390 } else {
391 currcons--;
392 viewed = 0;
393 }
394 ret = -ENXIO;
395 if (!vc_cons_allocated(currcons))
396 goto unlock_out;
397 vc = vc_cons[currcons].d;
398
399 size = vcs_size(inode);
400 ret = -EINVAL;
401 if (pos < 0 || pos > size)
402 goto unlock_out;
403 if (count > size - pos)
404 count = size - pos;
405 written = 0;
406 while (count) {
407 long this_round = count;
408 size_t orig_count;
409 long p;
410
411 if (this_round > CON_BUF_SIZE)
412 this_round = CON_BUF_SIZE;
413
414 /* Temporarily drop the console lock so that we can read
415 * in the write data from userspace safely.
416 */
417 release_console_sem();
418 ret = copy_from_user(con_buf, buf, this_round);
419 acquire_console_sem();
420
421 if (ret) {
422 this_round -= ret;
423 if (!this_round) {
424 /* Abort loop if no data were copied. Otherwise
425 * fail with -EFAULT.
426 */
427 if (written)
428 break;
429 ret = -EFAULT;
430 goto unlock_out;
431 }
432 }
433
434 /* The vcs_size might have changed while we slept to grab
435 * the user buffer, so recheck.
436 * Return data written up to now on failure.
437 */
438 size = vcs_size(inode);
439 if (pos >= size)
440 break;
441 if (this_round > size - pos)
442 this_round = size - pos;
443
444 /* OK, now actually push the write to the console
445 * under the lock using the local kernel buffer.
446 */
447
448 con_buf0 = con_buf;
449 orig_count = this_round;
450 maxcol = vc->vc_cols;
451 p = pos;
452 if (!attr) {
453 org0 = org = screen_pos(vc, p, viewed);
454 col = p % maxcol;
455 p += maxcol - col;
456
457 while (this_round > 0) {
458 unsigned char c = *con_buf0++;
459
460 this_round--;
461 vcs_scr_writew(vc,
462 (vcs_scr_readw(vc, org) & 0xff00) | c, org);
463 org++;
464 if (++col == maxcol) {
465 org = screen_pos(vc, p, viewed);
466 col = 0;
467 p += maxcol;
468 }
469 }
470 } else {
471 if (p < HEADER_SIZE) {
472 char header[HEADER_SIZE];
473
474 getconsxy(vc, header + 2);
475 while (p < HEADER_SIZE && this_round > 0) {
476 this_round--;
477 header[p++] = *con_buf0++;
478 }
479 if (!viewed)
480 putconsxy(vc, header + 2);
481 }
482 p -= HEADER_SIZE;
483 col = (p/2) % maxcol;
484 if (this_round > 0) {
485 org0 = org = screen_pos(vc, p/2, viewed);
486 if ((p & 1) && this_round > 0) {
487 char c;
488
489 this_round--;
490 c = *con_buf0++;
491#ifdef __BIG_ENDIAN
492 vcs_scr_writew(vc, c |
493 (vcs_scr_readw(vc, org) & 0xff00), org);
494#else
495 vcs_scr_writew(vc, (c << 8) |
496 (vcs_scr_readw(vc, org) & 0xff), org);
497#endif
498 org++;
499 p++;
500 if (++col == maxcol) {
501 org = screen_pos(vc, p/2, viewed);
502 col = 0;
503 }
504 }
505 p /= 2;
506 p += maxcol - col;
507 }
508 while (this_round > 1) {
509 unsigned short w;
510
Dave Jonesee025942005-12-28 20:01:04 -0500511 w = get_unaligned(((unsigned short *)con_buf0));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512 vcs_scr_writew(vc, w, org++);
513 con_buf0 += 2;
514 this_round -= 2;
515 if (++col == maxcol) {
516 org = screen_pos(vc, p, viewed);
517 col = 0;
518 p += maxcol;
519 }
520 }
521 if (this_round > 0) {
522 unsigned char c;
523
524 c = *con_buf0++;
525#ifdef __BIG_ENDIAN
526 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) | (c << 8), org);
527#else
528 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) | c, org);
529#endif
530 }
531 }
532 count -= orig_count;
533 written += orig_count;
534 buf += orig_count;
535 pos += orig_count;
536 if (org0)
537 update_region(vc, (unsigned long)(org0), org - org0);
538 }
539 *ppos += written;
540 ret = written;
Nicolas Pitre432c9ed2010-10-01 00:10:44 -0400541 if (written)
542 vcs_scr_updated(vc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543
544unlock_out:
545 release_console_sem();
546
Matthias Kaehlckec831c332007-05-08 00:39:49 -0700547 mutex_unlock(&con_buf_mtx);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548
549 return ret;
550}
551
Nicolas Pitre47725ac2010-10-05 14:22:37 -0400552static unsigned int
553vcs_poll(struct file *file, poll_table *wait)
554{
555 struct vcs_poll_data *poll = vcs_poll_data_get(file);
556 int ret = 0;
557
558 if (poll) {
559 poll_wait(file, &poll->waitq, wait);
560 if (!poll->seen_last_update)
561 ret = POLLIN | POLLRDNORM;
562 }
563 return ret;
564}
565
566static int
567vcs_fasync(int fd, struct file *file, int on)
568{
569 struct vcs_poll_data *poll = file->private_data;
570
571 if (!poll) {
572 /* don't allocate anything if all we want is disable fasync */
573 if (!on)
574 return 0;
575 poll = vcs_poll_data_get(file);
576 if (!poll)
577 return -ENOMEM;
578 }
579
580 return fasync_helper(fd, file, on, &poll->fasync);
581}
582
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583static int
584vcs_open(struct inode *inode, struct file *filp)
585{
586 unsigned int currcons = iminor(inode) & 127;
Jonathan Corbetf97259e2008-05-16 13:47:50 -0600587 int ret = 0;
588
Arnd Bergmannec79d602010-06-01 22:53:01 +0200589 tty_lock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700590 if(currcons && !vc_cons_allocated(currcons-1))
Jonathan Corbetf97259e2008-05-16 13:47:50 -0600591 ret = -ENXIO;
Arnd Bergmannec79d602010-06-01 22:53:01 +0200592 tty_unlock();
Jonathan Corbetf97259e2008-05-16 13:47:50 -0600593 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700594}
595
Nicolas Pitre47725ac2010-10-05 14:22:37 -0400596static int vcs_release(struct inode *inode, struct file *file)
597{
598 struct vcs_poll_data *poll = file->private_data;
599
600 if (poll)
601 vcs_poll_data_free(poll);
602 return 0;
603}
604
Arjan van de Ven62322d22006-07-03 00:24:21 -0700605static const struct file_operations vcs_fops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700606 .llseek = vcs_lseek,
607 .read = vcs_read,
608 .write = vcs_write,
Nicolas Pitre47725ac2010-10-05 14:22:37 -0400609 .poll = vcs_poll,
610 .fasync = vcs_fasync,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611 .open = vcs_open,
Nicolas Pitre47725ac2010-10-05 14:22:37 -0400612 .release = vcs_release,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613};
614
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800615static struct class *vc_class;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616
Kay Sievers4995f8e2009-03-09 14:18:52 +0100617void vcs_make_sysfs(int index)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618{
Kay Sievers4995f8e2009-03-09 14:18:52 +0100619 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
620 "vcs%u", index + 1);
621 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
622 "vcsa%u", index + 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700623}
Alan Coxd09d7dd2006-09-29 01:59:47 -0700624
Kay Sievers4995f8e2009-03-09 14:18:52 +0100625void vcs_remove_sysfs(int index)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700626{
Kay Sievers4995f8e2009-03-09 14:18:52 +0100627 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
628 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700629}
630
631int __init vcs_init(void)
632{
Kay Sieversc46a7ae2009-07-20 16:04:55 +0100633 unsigned int i;
634
Linus Torvalds1da177e2005-04-16 15:20:36 -0700635 if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
636 panic("unable to get major %d for vcs device", VCS_MAJOR);
gregkh@suse.deca8eca62005-03-23 09:53:09 -0800637 vc_class = class_create(THIS_MODULE, "vc");
Linus Torvalds1da177e2005-04-16 15:20:36 -0700638
Greg Kroah-Hartman03457cd2008-07-21 20:03:34 -0700639 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
640 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
Kay Sieversc46a7ae2009-07-20 16:04:55 +0100641 for (i = 0; i < MIN_NR_CONSOLES; i++)
642 vcs_make_sysfs(i);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643 return 0;
644}