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)
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.
12 * This replaces screendump and part of selection, so that the system
13 * administrator can control access using file system permissions.
15 * aeb@cwi.nl - efter Friedas begravelse - 950211
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
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>
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>
37 #include <linux/poll.h>
38 #include <linux/signal.h>
39 #include <linux/slab.h>
40 #include <linux/notifier.h>
42 #include <asm/uaccess.h>
43 #include <asm/byteorder.h>
44 #include <asm/unaligned.h>
51 #define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE)
53 struct 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;
62 vcs_notifier(struct notifier_block *nb, unsigned long code, void *_param)
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;
70 if (code != VT_UPDATE)
74 currcons = fg_console;
77 if (currcons != vc->vc_num)
80 poll->seen_last_update = false;
81 wake_up_interruptible(&poll->waitq);
82 kill_fasync(&poll->fasync, SIGIO, POLL_IN);
87 vcs_poll_data_free(struct vcs_poll_data *poll)
89 unregister_vt_notifier(&poll->notifier);
93 static struct vcs_poll_data *
94 vcs_poll_data_get(struct file *file)
96 struct vcs_poll_data *poll = file->private_data, *kill = NULL;
101 poll = kzalloc(sizeof(*poll), GFP_KERNEL);
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) {
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.
120 spin_lock(&file->f_lock);
121 if (!file->private_data) {
122 file->private_data = poll;
124 /* someone else raced ahead of us */
126 poll = file->private_data;
128 spin_unlock(&file->f_lock);
130 vcs_poll_data_free(kill);
136 * Returns VC for inode.
137 * Must be called with console_lock.
139 static struct vc_data*
140 vcs_vc(struct inode *inode, int *viewed)
142 unsigned int currcons = iminor(inode) & 127;
144 WARN_CONSOLE_UNLOCKED();
147 currcons = fg_console;
155 return vc_cons[currcons].d;
159 * Returns size for VC carried by inode.
160 * Must be called with console_lock.
163 vcs_size(struct inode *inode)
166 int minor = iminor(inode);
169 WARN_CONSOLE_UNLOCKED();
171 vc = vcs_vc(inode, NULL);
175 size = vc->vc_rows * vc->vc_cols;
178 size = 2*size + HEADER_SIZE;
182 static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
187 size = vcs_size(file_inode(file));
191 return fixed_size_llseek(file, offset, orig, size);
196 vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
198 struct inode *inode = file_inode(file);
199 unsigned int currcons = iminor(inode);
201 struct vcs_poll_data *poll;
204 int col, maxcol, viewed;
205 unsigned short *org = NULL;
209 con_buf = (char *) __get_free_page(GFP_KERNEL);
215 /* Select the proper current console and verify
216 * sanity of the situation under the console lock.
220 attr = (currcons & 128);
222 vc = vcs_vc(inode, &viewed);
229 poll = file->private_data;
231 poll->seen_last_update = true;
235 char *con_buf0, *con_buf_start;
236 long this_round, size;
240 /* Check whether we are above size each round,
241 * as copy_to_user at the end of this loop
244 size = vcs_size(inode);
253 if (count > size - pos)
257 if (this_round > CON_BUF_SIZE)
258 this_round = CON_BUF_SIZE;
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.
265 con_buf_start = con_buf0 = con_buf;
266 orig_count = this_round;
267 maxcol = vc->vc_cols;
269 org = screen_pos(vc, p, viewed);
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);
281 if (p < HEADER_SIZE) {
284 con_buf0[0] = (char)vc->vc_rows;
285 con_buf0[1] = (char)vc->vc_cols;
286 getconsxy(vc, con_buf0 + 2);
290 if (this_round > CON_BUF_SIZE) {
291 this_round = CON_BUF_SIZE;
292 orig_count = this_round - p;
295 tmp_count = HEADER_SIZE;
296 if (tmp_count > this_round)
297 tmp_count = this_round;
299 /* Advance state pointers and move on. */
300 this_round -= tmp_count;
302 con_buf0 = con_buf + HEADER_SIZE;
303 /* If this_round >= 0, then p is even... */
305 /* Skip first byte for output if start address is odd
306 * Update region sizes up/down depending on free
310 if (this_round < CON_BUF_SIZE)
315 if (this_round > 0) {
316 unsigned short *tmp_buf = (unsigned short *)con_buf0;
322 org = screen_pos(vc, p, viewed);
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.
329 this_round = (this_round + 1) >> 1;
332 *tmp_buf++ = vcs_scr_readw(vc, org++);
334 if (++col == maxcol) {
335 org = screen_pos(vc, p, viewed);
343 /* Finally, release the console semaphore while we push
344 * all the data to userspace from our temporary buffer.
346 * AKPM: Even though it's a semaphore, we should drop it because
347 * the pagefault handling code may want to call printk().
351 ret = copy_to_user(buf, con_buf_start, orig_count);
355 read += (orig_count - ret);
369 free_page((unsigned long) con_buf);
374 vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
376 struct inode *inode = file_inode(file);
377 unsigned int currcons = iminor(inode);
380 long attr, size, written;
382 int col, maxcol, viewed;
383 u16 *org0 = NULL, *org = NULL;
387 con_buf = (char *) __get_free_page(GFP_KERNEL);
393 /* Select the proper current console and verify
394 * sanity of the situation under the console lock.
398 attr = (currcons & 128);
400 vc = vcs_vc(inode, &viewed);
404 size = vcs_size(inode);
406 if (pos < 0 || pos > size)
408 if (count > size - pos)
412 long this_round = count;
416 if (this_round > CON_BUF_SIZE)
417 this_round = CON_BUF_SIZE;
419 /* Temporarily drop the console lock so that we can read
420 * in the write data from userspace safely.
423 ret = copy_from_user(con_buf, buf, this_round);
429 /* Abort loop if no data were copied. Otherwise
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.
443 size = vcs_size(inode);
452 if (this_round > size - pos)
453 this_round = size - pos;
455 /* OK, now actually push the write to the console
456 * under the lock using the local kernel buffer.
460 orig_count = this_round;
461 maxcol = vc->vc_cols;
464 org0 = org = screen_pos(vc, p, viewed);
468 while (this_round > 0) {
469 unsigned char c = *con_buf0++;
473 (vcs_scr_readw(vc, org) & 0xff00) | c, org);
475 if (++col == maxcol) {
476 org = screen_pos(vc, p, viewed);
482 if (p < HEADER_SIZE) {
483 char header[HEADER_SIZE];
485 getconsxy(vc, header + 2);
486 while (p < HEADER_SIZE && this_round > 0) {
488 header[p++] = *con_buf0++;
491 putconsxy(vc, header + 2);
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) {
503 vcs_scr_writew(vc, c |
504 (vcs_scr_readw(vc, org) & 0xff00), org);
506 vcs_scr_writew(vc, (c << 8) |
507 (vcs_scr_readw(vc, org) & 0xff), org);
511 if (++col == maxcol) {
512 org = screen_pos(vc, p/2, viewed);
519 while (this_round > 1) {
522 w = get_unaligned(((unsigned short *)con_buf0));
523 vcs_scr_writew(vc, w, org++);
526 if (++col == maxcol) {
527 org = screen_pos(vc, p, viewed);
532 if (this_round > 0) {
537 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) | (c << 8), org);
539 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) | c, org);
544 written += orig_count;
548 update_region(vc, (unsigned long)(org0), org - org0);
557 free_page((unsigned long) con_buf);
562 vcs_poll(struct file *file, poll_table *wait)
564 struct vcs_poll_data *poll = vcs_poll_data_get(file);
565 int ret = DEFAULT_POLLMASK|POLLERR|POLLPRI;
568 poll_wait(file, &poll->waitq, wait);
569 if (poll->seen_last_update)
570 ret = DEFAULT_POLLMASK;
576 vcs_fasync(int fd, struct file *file, int on)
578 struct vcs_poll_data *poll = file->private_data;
581 /* don't allocate anything if all we want is disable fasync */
584 poll = vcs_poll_data_get(file);
589 return fasync_helper(fd, file, on, &poll->fasync);
593 vcs_open(struct inode *inode, struct file *filp)
595 unsigned int currcons = iminor(inode) & 127;
599 if(currcons && !vc_cons_allocated(currcons-1))
605 static int vcs_release(struct inode *inode, struct file *file)
607 struct vcs_poll_data *poll = file->private_data;
610 vcs_poll_data_free(poll);
614 static const struct file_operations vcs_fops = {
619 .fasync = vcs_fasync,
621 .release = vcs_release,
624 static struct class *vc_class;
626 void vcs_make_sysfs(int index)
628 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
630 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
631 "vcsa%u", index + 1);
634 void vcs_remove_sysfs(int index)
636 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
637 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
640 int __init vcs_init(void)
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");
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++)