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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 <asm/unaligned.h>
52
53#define HEADER_SIZE 4u
54#define CON_BUF_SIZE (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
76struct 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
84static int
85vcs_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
118static void
119vcs_poll_data_free(struct vcs_poll_data *poll)
120{
121 unregister_vt_notifier(&poll->notifier);
122 kfree(poll);
123}
124
125static struct vcs_poll_data *
126vcs_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 */
183static 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 */
209static 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
228static 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
248static 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
276static 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
296static 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
364static ssize_t
365vcs_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 ret = -ENXIO;
407 vc = vcs_vc(inode, &viewed);
408 if (!vc)
409 goto unlock_out;
410
411 /* Check whether we are above size each round,
412 * as copy_to_user at the end of this loop
413 * could sleep.
414 */
415 size = vcs_size(vc, attr, uni_mode);
416 if (size < 0) {
417 if (read)
418 break;
419 ret = size;
420 goto unlock_out;
421 }
422 if (pos >= size)
423 break;
424 if (count > size - pos)
425 count = size - pos;
426
427 this_round = count;
428 if (this_round > CON_BUF_SIZE)
429 this_round = CON_BUF_SIZE;
430
431 /* Perform the whole read into the local con_buf.
432 * Then we can drop the console spinlock and safely
433 * attempt to move it to userspace.
434 */
435
436 if (uni_mode) {
437 ret = vcs_read_buf_uni(vc, con_buf, pos, this_round,
438 viewed);
439 if (ret)
440 break;
441 } else if (!attr) {
442 vcs_read_buf_noattr(vc, con_buf, pos, this_round,
443 viewed);
444 } else {
445 this_round = vcs_read_buf(vc, con_buf, pos, this_round,
446 viewed, &skip);
447 }
448
449 /* Finally, release the console semaphore while we push
450 * all the data to userspace from our temporary buffer.
451 *
452 * AKPM: Even though it's a semaphore, we should drop it because
453 * the pagefault handling code may want to call printk().
454 */
455
456 console_unlock();
457 ret = copy_to_user(buf, con_buf + skip, this_round);
458 console_lock();
459
460 if (ret) {
461 read += this_round - ret;
462 ret = -EFAULT;
463 break;
464 }
465 buf += this_round;
466 pos += this_round;
467 read += this_round;
468 count -= this_round;
469 }
470 *ppos += read;
471 if (read)
472 ret = read;
473unlock_out:
474 console_unlock();
475 free_page((unsigned long) con_buf);
476 return ret;
477}
478
479static u16 *vcs_write_buf_noattr(struct vc_data *vc, const char *con_buf,
480 unsigned int pos, unsigned int count, bool viewed, u16 **org0)
481{
482 u16 *org;
483 unsigned int col, maxcol = vc->vc_cols;
484
485 *org0 = org = screen_pos(vc, pos, viewed);
486 col = pos % maxcol;
487 pos += maxcol - col;
488
489 while (count > 0) {
490 unsigned char c = *con_buf++;
491
492 count--;
493 vcs_scr_writew(vc,
494 (vcs_scr_readw(vc, org) & 0xff00) | c, org);
495 org++;
496 if (++col == maxcol) {
497 org = screen_pos(vc, pos, viewed);
498 col = 0;
499 pos += maxcol;
500 }
501 }
502
503 return org;
504}
505
506/*
507 * Compilers (gcc 10) are unable to optimize the swap in cpu_to_le16. So do it
508 * the poor man way.
509 */
510static inline u16 vc_compile_le16(u8 hi, u8 lo)
511{
512#ifdef __BIG_ENDIAN
513 return (lo << 8u) | hi;
514#else
515 return (hi << 8u) | lo;
516#endif
517}
518
519static u16 *vcs_write_buf(struct vc_data *vc, const char *con_buf,
520 unsigned int pos, unsigned int count, bool viewed, u16 **org0)
521{
522 u16 *org;
523 unsigned int col, maxcol = vc->vc_cols;
524 unsigned char c;
525
526 /* header */
527 if (pos < HEADER_SIZE) {
528 char header[HEADER_SIZE];
529
530 getconsxy(vc, header + 2);
531 while (pos < HEADER_SIZE && count > 0) {
532 count--;
533 header[pos++] = *con_buf++;
534 }
535 if (!viewed)
536 putconsxy(vc, header + 2);
537 }
538
539 if (!count)
540 return NULL;
541
542 pos -= HEADER_SIZE;
543 col = (pos/2) % maxcol;
544
545 *org0 = org = screen_pos(vc, pos/2, viewed);
546
547 /* odd pos -- the first single character */
548 if (pos & 1) {
549 count--;
550 c = *con_buf++;
551 vcs_scr_writew(vc, vc_compile_le16(c, vcs_scr_readw(vc, org)),
552 org);
553 org++;
554 pos++;
555 if (++col == maxcol) {
556 org = screen_pos(vc, pos/2, viewed);
557 col = 0;
558 }
559 }
560
561 pos /= 2;
562 pos += maxcol - col;
563
564 /* even pos -- handle attr+character pairs */
565 while (count > 1) {
566 unsigned short w;
567
568 w = get_unaligned(((unsigned short *)con_buf));
569 vcs_scr_writew(vc, w, org++);
570 con_buf += 2;
571 count -= 2;
572 if (++col == maxcol) {
573 org = screen_pos(vc, pos, viewed);
574 col = 0;
575 pos += maxcol;
576 }
577 }
578
579 if (!count)
580 return org;
581
582 /* odd pos -- the remaining character */
583 c = *con_buf++;
584 vcs_scr_writew(vc, vc_compile_le16(vcs_scr_readw(vc, org) >> 8, c),
585 org);
586
587 return org;
588}
589
590static ssize_t
591vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
592{
593 struct inode *inode = file_inode(file);
594 struct vc_data *vc;
595 char *con_buf;
596 u16 *org0, *org;
597 unsigned int written;
598 int size;
599 ssize_t ret;
600 loff_t pos;
601 bool viewed, attr;
602
603 if (use_unicode(inode))
604 return -EOPNOTSUPP;
605
606 con_buf = (char *) __get_free_page(GFP_KERNEL);
607 if (!con_buf)
608 return -ENOMEM;
609
610 pos = *ppos;
611
612 /* Select the proper current console and verify
613 * sanity of the situation under the console lock.
614 */
615 console_lock();
616
617 attr = use_attributes(inode);
618 ret = -ENXIO;
619 vc = vcs_vc(inode, &viewed);
620 if (!vc)
621 goto unlock_out;
622
623 size = vcs_size(vc, attr, false);
624 if (size < 0) {
625 ret = size;
626 goto unlock_out;
627 }
628 ret = -EINVAL;
629 if (pos < 0 || pos > size)
630 goto unlock_out;
631 if (count > size - pos)
632 count = size - pos;
633 written = 0;
634 while (count) {
635 unsigned int this_round = count;
636
637 if (this_round > CON_BUF_SIZE)
638 this_round = CON_BUF_SIZE;
639
640 /* Temporarily drop the console lock so that we can read
641 * in the write data from userspace safely.
642 */
643 console_unlock();
644 ret = copy_from_user(con_buf, buf, this_round);
645 console_lock();
646
647 if (ret) {
648 this_round -= ret;
649 if (!this_round) {
650 /* Abort loop if no data were copied. Otherwise
651 * fail with -EFAULT.
652 */
653 if (written)
654 break;
655 ret = -EFAULT;
656 goto unlock_out;
657 }
658 }
659
660 /* The vcs_size might have changed while we slept to grab
661 * the user buffer, so recheck.
662 * Return data written up to now on failure.
663 */
664 size = vcs_size(vc, attr, false);
665 if (size < 0) {
666 if (written)
667 break;
668 ret = size;
669 goto unlock_out;
670 }
671 if (pos >= size)
672 break;
673 if (this_round > size - pos)
674 this_round = size - pos;
675
676 /* OK, now actually push the write to the console
677 * under the lock using the local kernel buffer.
678 */
679
680 if (attr)
681 org = vcs_write_buf(vc, con_buf, pos, this_round,
682 viewed, &org0);
683 else
684 org = vcs_write_buf_noattr(vc, con_buf, pos, this_round,
685 viewed, &org0);
686
687 count -= this_round;
688 written += this_round;
689 buf += this_round;
690 pos += this_round;
691 if (org)
692 update_region(vc, (unsigned long)(org0), org - org0);
693 }
694 *ppos += written;
695 ret = written;
696 if (written)
697 vcs_scr_updated(vc);
698
699unlock_out:
700 console_unlock();
701 free_page((unsigned long) con_buf);
702 return ret;
703}
704
705static __poll_t
706vcs_poll(struct file *file, poll_table *wait)
707{
708 struct vcs_poll_data *poll = vcs_poll_data_get(file);
709 __poll_t ret = DEFAULT_POLLMASK|EPOLLERR;
710
711 if (poll) {
712 poll_wait(file, &poll->waitq, wait);
713 switch (poll->event) {
714 case VT_UPDATE:
715 ret = DEFAULT_POLLMASK|EPOLLPRI;
716 break;
717 case VT_DEALLOCATE:
718 ret = DEFAULT_POLLMASK|EPOLLHUP|EPOLLERR;
719 break;
720 case 0:
721 ret = DEFAULT_POLLMASK;
722 break;
723 }
724 }
725 return ret;
726}
727
728static int
729vcs_fasync(int fd, struct file *file, int on)
730{
731 struct vcs_poll_data *poll = file->private_data;
732
733 if (!poll) {
734 /* don't allocate anything if all we want is disable fasync */
735 if (!on)
736 return 0;
737 poll = vcs_poll_data_get(file);
738 if (!poll)
739 return -ENOMEM;
740 }
741
742 return fasync_helper(fd, file, on, &poll->fasync);
743}
744
745static int
746vcs_open(struct inode *inode, struct file *filp)
747{
748 unsigned int currcons = console(inode);
749 bool attr = use_attributes(inode);
750 bool uni_mode = use_unicode(inode);
751 int ret = 0;
752
753 /* we currently don't support attributes in unicode mode */
754 if (attr && uni_mode)
755 return -EOPNOTSUPP;
756
757 console_lock();
758 if(currcons && !vc_cons_allocated(currcons-1))
759 ret = -ENXIO;
760 console_unlock();
761 return ret;
762}
763
764static int vcs_release(struct inode *inode, struct file *file)
765{
766 struct vcs_poll_data *poll = file->private_data;
767
768 if (poll)
769 vcs_poll_data_free(poll);
770 return 0;
771}
772
773static const struct file_operations vcs_fops = {
774 .llseek = vcs_lseek,
775 .read = vcs_read,
776 .write = vcs_write,
777 .poll = vcs_poll,
778 .fasync = vcs_fasync,
779 .open = vcs_open,
780 .release = vcs_release,
781};
782
783static struct class *vc_class;
784
785void vcs_make_sysfs(int index)
786{
787 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
788 "vcs%u", index + 1);
789 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 65), NULL,
790 "vcsu%u", index + 1);
791 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
792 "vcsa%u", index + 1);
793}
794
795void vcs_remove_sysfs(int index)
796{
797 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
798 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 65));
799 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
800}
801
802int __init vcs_init(void)
803{
804 unsigned int i;
805
806 if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
807 panic("unable to get major %d for vcs device", VCS_MAJOR);
808 vc_class = class_create(THIS_MODULE, "vc");
809
810 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
811 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 64), NULL, "vcsu");
812 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
813 for (i = 0; i < MIN_NR_CONSOLES; i++)
814 vcs_make_sysfs(i);
815 return 0;
816}
1/*
2 * Provide access to virtual console memory.
3 * /dev/vcs0: the screen as it is being viewed right now (possibly scrolled)
4 * /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63)
5 * [minor: N]
6 *
7 * /dev/vcsaN: idem, but including attributes, and prefixed with
8 * the 4 bytes lines,columns,x,y (as screendump used to give).
9 * Attribute/character pair is in native endianity.
10 * [minor: N+128]
11 *
12 * This replaces screendump and part of selection, so that the system
13 * administrator can control access using file system permissions.
14 *
15 * aeb@cwi.nl - efter Friedas begravelse - 950211
16 *
17 * machek@k332.feld.cvut.cz - modified not to send characters to wrong console
18 * - fixed some fatal off-by-one bugs (0-- no longer == -1 -> looping and looping and looping...)
19 * - making it shorter - scr_readw are macros which expand in PRETTY long code
20 */
21
22#include <linux/kernel.h>
23#include <linux/major.h>
24#include <linux/errno.h>
25#include <linux/export.h>
26#include <linux/tty.h>
27#include <linux/interrupt.h>
28#include <linux/mm.h>
29#include <linux/init.h>
30#include <linux/vt_kern.h>
31#include <linux/selection.h>
32#include <linux/kbd_kern.h>
33#include <linux/console.h>
34#include <linux/device.h>
35#include <linux/sched.h>
36#include <linux/fs.h>
37#include <linux/poll.h>
38#include <linux/signal.h>
39#include <linux/slab.h>
40#include <linux/notifier.h>
41
42#include <asm/uaccess.h>
43#include <asm/byteorder.h>
44#include <asm/unaligned.h>
45
46#undef attr
47#undef org
48#undef addr
49#define HEADER_SIZE 4
50
51#define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE)
52
53struct vcs_poll_data {
54 struct notifier_block notifier;
55 unsigned int cons_num;
56 bool seen_last_update;
57 wait_queue_head_t waitq;
58 struct fasync_struct *fasync;
59};
60
61static int
62vcs_notifier(struct notifier_block *nb, unsigned long code, void *_param)
63{
64 struct vt_notifier_param *param = _param;
65 struct vc_data *vc = param->vc;
66 struct vcs_poll_data *poll =
67 container_of(nb, struct vcs_poll_data, notifier);
68 int currcons = poll->cons_num;
69
70 if (code != VT_UPDATE)
71 return NOTIFY_DONE;
72
73 if (currcons == 0)
74 currcons = fg_console;
75 else
76 currcons--;
77 if (currcons != vc->vc_num)
78 return NOTIFY_DONE;
79
80 poll->seen_last_update = false;
81 wake_up_interruptible(&poll->waitq);
82 kill_fasync(&poll->fasync, SIGIO, POLL_IN);
83 return NOTIFY_OK;
84}
85
86static void
87vcs_poll_data_free(struct vcs_poll_data *poll)
88{
89 unregister_vt_notifier(&poll->notifier);
90 kfree(poll);
91}
92
93static struct vcs_poll_data *
94vcs_poll_data_get(struct file *file)
95{
96 struct vcs_poll_data *poll = file->private_data, *kill = NULL;
97
98 if (poll)
99 return poll;
100
101 poll = kzalloc(sizeof(*poll), GFP_KERNEL);
102 if (!poll)
103 return NULL;
104 poll->cons_num = iminor(file_inode(file)) & 127;
105 init_waitqueue_head(&poll->waitq);
106 poll->notifier.notifier_call = vcs_notifier;
107 if (register_vt_notifier(&poll->notifier) != 0) {
108 kfree(poll);
109 return NULL;
110 }
111
112 /*
113 * This code may be called either through ->poll() or ->fasync().
114 * If we have two threads using the same file descriptor, they could
115 * both enter this function, both notice that the structure hasn't
116 * been allocated yet and go ahead allocating it in parallel, but
117 * only one of them must survive and be shared otherwise we'd leak
118 * memory with a dangling notifier callback.
119 */
120 spin_lock(&file->f_lock);
121 if (!file->private_data) {
122 file->private_data = poll;
123 } else {
124 /* someone else raced ahead of us */
125 kill = poll;
126 poll = file->private_data;
127 }
128 spin_unlock(&file->f_lock);
129 if (kill)
130 vcs_poll_data_free(kill);
131
132 return poll;
133}
134
135/*
136 * Returns VC for inode.
137 * Must be called with console_lock.
138 */
139static struct vc_data*
140vcs_vc(struct inode *inode, int *viewed)
141{
142 unsigned int currcons = iminor(inode) & 127;
143
144 WARN_CONSOLE_UNLOCKED();
145
146 if (currcons == 0) {
147 currcons = fg_console;
148 if (viewed)
149 *viewed = 1;
150 } else {
151 currcons--;
152 if (viewed)
153 *viewed = 0;
154 }
155 return vc_cons[currcons].d;
156}
157
158/*
159 * Returns size for VC carried by inode.
160 * Must be called with console_lock.
161 */
162static int
163vcs_size(struct inode *inode)
164{
165 int size;
166 int minor = iminor(inode);
167 struct vc_data *vc;
168
169 WARN_CONSOLE_UNLOCKED();
170
171 vc = vcs_vc(inode, NULL);
172 if (!vc)
173 return -ENXIO;
174
175 size = vc->vc_rows * vc->vc_cols;
176
177 if (minor & 128)
178 size = 2*size + HEADER_SIZE;
179 return size;
180}
181
182static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
183{
184 int size;
185
186 console_lock();
187 size = vcs_size(file_inode(file));
188 console_unlock();
189 if (size < 0)
190 return size;
191 return fixed_size_llseek(file, offset, orig, size);
192}
193
194
195static ssize_t
196vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
197{
198 struct inode *inode = file_inode(file);
199 unsigned int currcons = iminor(inode);
200 struct vc_data *vc;
201 struct vcs_poll_data *poll;
202 long pos;
203 long attr, read;
204 int col, maxcol, viewed;
205 unsigned short *org = NULL;
206 ssize_t ret;
207 char *con_buf;
208
209 con_buf = (char *) __get_free_page(GFP_KERNEL);
210 if (!con_buf)
211 return -ENOMEM;
212
213 pos = *ppos;
214
215 /* Select the proper current console and verify
216 * sanity of the situation under the console lock.
217 */
218 console_lock();
219
220 attr = (currcons & 128);
221 ret = -ENXIO;
222 vc = vcs_vc(inode, &viewed);
223 if (!vc)
224 goto unlock_out;
225
226 ret = -EINVAL;
227 if (pos < 0)
228 goto unlock_out;
229 poll = file->private_data;
230 if (count && poll)
231 poll->seen_last_update = true;
232 read = 0;
233 ret = 0;
234 while (count) {
235 char *con_buf0, *con_buf_start;
236 long this_round, size;
237 ssize_t orig_count;
238 long p = pos;
239
240 /* Check whether we are above size each round,
241 * as copy_to_user at the end of this loop
242 * could sleep.
243 */
244 size = vcs_size(inode);
245 if (size < 0) {
246 if (read)
247 break;
248 ret = size;
249 goto unlock_out;
250 }
251 if (pos >= size)
252 break;
253 if (count > size - pos)
254 count = size - pos;
255
256 this_round = count;
257 if (this_round > CON_BUF_SIZE)
258 this_round = CON_BUF_SIZE;
259
260 /* Perform the whole read into the local con_buf.
261 * Then we can drop the console spinlock and safely
262 * attempt to move it to userspace.
263 */
264
265 con_buf_start = con_buf0 = con_buf;
266 orig_count = this_round;
267 maxcol = vc->vc_cols;
268 if (!attr) {
269 org = screen_pos(vc, p, viewed);
270 col = p % maxcol;
271 p += maxcol - col;
272 while (this_round-- > 0) {
273 *con_buf0++ = (vcs_scr_readw(vc, org++) & 0xff);
274 if (++col == maxcol) {
275 org = screen_pos(vc, p, viewed);
276 col = 0;
277 p += maxcol;
278 }
279 }
280 } else {
281 if (p < HEADER_SIZE) {
282 size_t tmp_count;
283
284 con_buf0[0] = (char)vc->vc_rows;
285 con_buf0[1] = (char)vc->vc_cols;
286 getconsxy(vc, con_buf0 + 2);
287
288 con_buf_start += p;
289 this_round += p;
290 if (this_round > CON_BUF_SIZE) {
291 this_round = CON_BUF_SIZE;
292 orig_count = this_round - p;
293 }
294
295 tmp_count = HEADER_SIZE;
296 if (tmp_count > this_round)
297 tmp_count = this_round;
298
299 /* Advance state pointers and move on. */
300 this_round -= tmp_count;
301 p = HEADER_SIZE;
302 con_buf0 = con_buf + HEADER_SIZE;
303 /* If this_round >= 0, then p is even... */
304 } else if (p & 1) {
305 /* Skip first byte for output if start address is odd
306 * Update region sizes up/down depending on free
307 * space in buffer.
308 */
309 con_buf_start++;
310 if (this_round < CON_BUF_SIZE)
311 this_round++;
312 else
313 orig_count--;
314 }
315 if (this_round > 0) {
316 unsigned short *tmp_buf = (unsigned short *)con_buf0;
317
318 p -= HEADER_SIZE;
319 p /= 2;
320 col = p % maxcol;
321
322 org = screen_pos(vc, p, viewed);
323 p += maxcol - col;
324
325 /* Buffer has even length, so we can always copy
326 * character + attribute. We do not copy last byte
327 * to userspace if this_round is odd.
328 */
329 this_round = (this_round + 1) >> 1;
330
331 while (this_round) {
332 *tmp_buf++ = vcs_scr_readw(vc, org++);
333 this_round --;
334 if (++col == maxcol) {
335 org = screen_pos(vc, p, viewed);
336 col = 0;
337 p += maxcol;
338 }
339 }
340 }
341 }
342
343 /* Finally, release the console semaphore while we push
344 * all the data to userspace from our temporary buffer.
345 *
346 * AKPM: Even though it's a semaphore, we should drop it because
347 * the pagefault handling code may want to call printk().
348 */
349
350 console_unlock();
351 ret = copy_to_user(buf, con_buf_start, orig_count);
352 console_lock();
353
354 if (ret) {
355 read += (orig_count - ret);
356 ret = -EFAULT;
357 break;
358 }
359 buf += orig_count;
360 pos += orig_count;
361 read += orig_count;
362 count -= orig_count;
363 }
364 *ppos += read;
365 if (read)
366 ret = read;
367unlock_out:
368 console_unlock();
369 free_page((unsigned long) con_buf);
370 return ret;
371}
372
373static ssize_t
374vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
375{
376 struct inode *inode = file_inode(file);
377 unsigned int currcons = iminor(inode);
378 struct vc_data *vc;
379 long pos;
380 long attr, size, written;
381 char *con_buf0;
382 int col, maxcol, viewed;
383 u16 *org0 = NULL, *org = NULL;
384 size_t ret;
385 char *con_buf;
386
387 con_buf = (char *) __get_free_page(GFP_KERNEL);
388 if (!con_buf)
389 return -ENOMEM;
390
391 pos = *ppos;
392
393 /* Select the proper current console and verify
394 * sanity of the situation under the console lock.
395 */
396 console_lock();
397
398 attr = (currcons & 128);
399 ret = -ENXIO;
400 vc = vcs_vc(inode, &viewed);
401 if (!vc)
402 goto unlock_out;
403
404 size = vcs_size(inode);
405 ret = -EINVAL;
406 if (pos < 0 || pos > size)
407 goto unlock_out;
408 if (count > size - pos)
409 count = size - pos;
410 written = 0;
411 while (count) {
412 long this_round = count;
413 size_t orig_count;
414 long p;
415
416 if (this_round > CON_BUF_SIZE)
417 this_round = CON_BUF_SIZE;
418
419 /* Temporarily drop the console lock so that we can read
420 * in the write data from userspace safely.
421 */
422 console_unlock();
423 ret = copy_from_user(con_buf, buf, this_round);
424 console_lock();
425
426 if (ret) {
427 this_round -= ret;
428 if (!this_round) {
429 /* Abort loop if no data were copied. Otherwise
430 * fail with -EFAULT.
431 */
432 if (written)
433 break;
434 ret = -EFAULT;
435 goto unlock_out;
436 }
437 }
438
439 /* The vcs_size might have changed while we slept to grab
440 * the user buffer, so recheck.
441 * Return data written up to now on failure.
442 */
443 size = vcs_size(inode);
444 if (size < 0) {
445 if (written)
446 break;
447 ret = size;
448 goto unlock_out;
449 }
450 if (pos >= size)
451 break;
452 if (this_round > size - pos)
453 this_round = size - pos;
454
455 /* OK, now actually push the write to the console
456 * under the lock using the local kernel buffer.
457 */
458
459 con_buf0 = con_buf;
460 orig_count = this_round;
461 maxcol = vc->vc_cols;
462 p = pos;
463 if (!attr) {
464 org0 = org = screen_pos(vc, p, viewed);
465 col = p % maxcol;
466 p += maxcol - col;
467
468 while (this_round > 0) {
469 unsigned char c = *con_buf0++;
470
471 this_round--;
472 vcs_scr_writew(vc,
473 (vcs_scr_readw(vc, org) & 0xff00) | c, org);
474 org++;
475 if (++col == maxcol) {
476 org = screen_pos(vc, p, viewed);
477 col = 0;
478 p += maxcol;
479 }
480 }
481 } else {
482 if (p < HEADER_SIZE) {
483 char header[HEADER_SIZE];
484
485 getconsxy(vc, header + 2);
486 while (p < HEADER_SIZE && this_round > 0) {
487 this_round--;
488 header[p++] = *con_buf0++;
489 }
490 if (!viewed)
491 putconsxy(vc, header + 2);
492 }
493 p -= HEADER_SIZE;
494 col = (p/2) % maxcol;
495 if (this_round > 0) {
496 org0 = org = screen_pos(vc, p/2, viewed);
497 if ((p & 1) && this_round > 0) {
498 char c;
499
500 this_round--;
501 c = *con_buf0++;
502#ifdef __BIG_ENDIAN
503 vcs_scr_writew(vc, c |
504 (vcs_scr_readw(vc, org) & 0xff00), org);
505#else
506 vcs_scr_writew(vc, (c << 8) |
507 (vcs_scr_readw(vc, org) & 0xff), org);
508#endif
509 org++;
510 p++;
511 if (++col == maxcol) {
512 org = screen_pos(vc, p/2, viewed);
513 col = 0;
514 }
515 }
516 p /= 2;
517 p += maxcol - col;
518 }
519 while (this_round > 1) {
520 unsigned short w;
521
522 w = get_unaligned(((unsigned short *)con_buf0));
523 vcs_scr_writew(vc, w, org++);
524 con_buf0 += 2;
525 this_round -= 2;
526 if (++col == maxcol) {
527 org = screen_pos(vc, p, viewed);
528 col = 0;
529 p += maxcol;
530 }
531 }
532 if (this_round > 0) {
533 unsigned char c;
534
535 c = *con_buf0++;
536#ifdef __BIG_ENDIAN
537 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) | (c << 8), org);
538#else
539 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) | c, org);
540#endif
541 }
542 }
543 count -= orig_count;
544 written += orig_count;
545 buf += orig_count;
546 pos += orig_count;
547 if (org0)
548 update_region(vc, (unsigned long)(org0), org - org0);
549 }
550 *ppos += written;
551 ret = written;
552 if (written)
553 vcs_scr_updated(vc);
554
555unlock_out:
556 console_unlock();
557 free_page((unsigned long) con_buf);
558 return ret;
559}
560
561static unsigned int
562vcs_poll(struct file *file, poll_table *wait)
563{
564 struct vcs_poll_data *poll = vcs_poll_data_get(file);
565 int ret = DEFAULT_POLLMASK|POLLERR|POLLPRI;
566
567 if (poll) {
568 poll_wait(file, &poll->waitq, wait);
569 if (poll->seen_last_update)
570 ret = DEFAULT_POLLMASK;
571 }
572 return ret;
573}
574
575static int
576vcs_fasync(int fd, struct file *file, int on)
577{
578 struct vcs_poll_data *poll = file->private_data;
579
580 if (!poll) {
581 /* don't allocate anything if all we want is disable fasync */
582 if (!on)
583 return 0;
584 poll = vcs_poll_data_get(file);
585 if (!poll)
586 return -ENOMEM;
587 }
588
589 return fasync_helper(fd, file, on, &poll->fasync);
590}
591
592static int
593vcs_open(struct inode *inode, struct file *filp)
594{
595 unsigned int currcons = iminor(inode) & 127;
596 int ret = 0;
597
598 console_lock();
599 if(currcons && !vc_cons_allocated(currcons-1))
600 ret = -ENXIO;
601 console_unlock();
602 return ret;
603}
604
605static int vcs_release(struct inode *inode, struct file *file)
606{
607 struct vcs_poll_data *poll = file->private_data;
608
609 if (poll)
610 vcs_poll_data_free(poll);
611 return 0;
612}
613
614static const struct file_operations vcs_fops = {
615 .llseek = vcs_lseek,
616 .read = vcs_read,
617 .write = vcs_write,
618 .poll = vcs_poll,
619 .fasync = vcs_fasync,
620 .open = vcs_open,
621 .release = vcs_release,
622};
623
624static struct class *vc_class;
625
626void vcs_make_sysfs(int index)
627{
628 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
629 "vcs%u", index + 1);
630 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
631 "vcsa%u", index + 1);
632}
633
634void vcs_remove_sysfs(int index)
635{
636 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
637 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
638}
639
640int __init vcs_init(void)
641{
642 unsigned int i;
643
644 if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
645 panic("unable to get major %d for vcs device", VCS_MAJOR);
646 vc_class = class_create(THIS_MODULE, "vc");
647
648 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
649 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
650 for (i = 0; i < MIN_NR_CONSOLES; i++)
651 vcs_make_sysfs(i);
652 return 0;
653}