2 * linux/drivers/char/vc_screen.c
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)
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.
14 * This replaces screendump and part of selection, so that the system
15 * administrator can control access using file system permissions.
17 * aeb@cwi.nl - efter Friedas begravelse - 950211
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
24 #include <linux/kernel.h>
25 #include <linux/major.h>
26 #include <linux/errno.h>
27 #include <linux/tty.h>
28 #include <linux/interrupt.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>
35 #include <linux/device.h>
36 #include <asm/uaccess.h>
37 #include <asm/byteorder.h>
38 #include <asm/unaligned.h>
46 vcs_size(struct inode
*inode
)
49 int minor
= iminor(inode
);
50 int currcons
= minor
& 127;
54 currcons
= fg_console
;
57 if (!vc_cons_allocated(currcons
))
59 vc
= vc_cons
[currcons
].d
;
61 size
= vc
->vc_rows
* vc
->vc_cols
;
64 size
= 2*size
+ HEADER_SIZE
;
68 static loff_t
vcs_lseek(struct file
*file
, loff_t offset
, int orig
)
73 size
= vcs_size(file
->f_path
.dentry
->d_inode
);
82 offset
+= file
->f_pos
;
86 if (offset
< 0 || offset
> size
) {
97 vcs_read(struct file
*file
, char __user
*buf
, size_t count
, loff_t
*ppos
)
99 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
100 unsigned int currcons
= iminor(inode
);
103 long viewed
, attr
, read
;
105 unsigned short *org
= NULL
;
112 /* Select the proper current console and verify
113 * sanity of the situation under the console lock.
115 acquire_console_sem();
117 attr
= (currcons
& 128);
118 currcons
= (currcons
& 127);
120 currcons
= fg_console
;
127 if (!vc_cons_allocated(currcons
))
129 vc
= vc_cons
[currcons
].d
;
137 char *con_buf0
, *con_buf_start
;
138 long this_round
, size
;
142 /* Check whether we are above size each round,
143 * as copy_to_user at the end of this loop
146 size
= vcs_size(inode
);
149 if (count
> size
- pos
)
153 if (this_round
> CON_BUF_SIZE
)
154 this_round
= CON_BUF_SIZE
;
156 /* Perform the whole read into the local con_buf.
157 * Then we can drop the console spinlock and safely
158 * attempt to move it to userspace.
161 con_buf_start
= con_buf0
= con_buf
;
162 orig_count
= this_round
;
163 maxcol
= vc
->vc_cols
;
165 org
= screen_pos(vc
, p
, viewed
);
168 while (this_round
-- > 0) {
169 *con_buf0
++ = (vcs_scr_readw(vc
, org
++) & 0xff);
170 if (++col
== maxcol
) {
171 org
= screen_pos(vc
, p
, viewed
);
177 if (p
< HEADER_SIZE
) {
180 con_buf0
[0] = (char)vc
->vc_rows
;
181 con_buf0
[1] = (char)vc
->vc_cols
;
182 getconsxy(vc
, con_buf0
+ 2);
186 if (this_round
> CON_BUF_SIZE
) {
187 this_round
= CON_BUF_SIZE
;
188 orig_count
= this_round
- p
;
191 tmp_count
= HEADER_SIZE
;
192 if (tmp_count
> this_round
)
193 tmp_count
= this_round
;
195 /* Advance state pointers and move on. */
196 this_round
-= tmp_count
;
198 con_buf0
= con_buf
+ HEADER_SIZE
;
199 /* If this_round >= 0, then p is even... */
201 /* Skip first byte for output if start address is odd
202 * Update region sizes up/down depending on free
206 if (this_round
< CON_BUF_SIZE
)
211 if (this_round
> 0) {
212 unsigned short *tmp_buf
= (unsigned short *)con_buf0
;
218 org
= screen_pos(vc
, p
, viewed
);
221 /* Buffer has even length, so we can always copy
222 * character + attribute. We do not copy last byte
223 * to userspace if this_round is odd.
225 this_round
= (this_round
+ 1) >> 1;
228 *tmp_buf
++ = vcs_scr_readw(vc
, org
++);
230 if (++col
== maxcol
) {
231 org
= screen_pos(vc
, p
, viewed
);
239 /* Finally, release the console semaphore while we push
240 * all the data to userspace from our temporary buffer.
242 * AKPM: Even though it's a semaphore, we should drop it because
243 * the pagefault handling code may want to call printk().
246 release_console_sem();
247 ret
= copy_to_user(buf
, con_buf_start
, orig_count
);
248 acquire_console_sem();
251 read
+= (orig_count
- ret
);
264 release_console_sem();
270 vcs_write(struct file
*file
, const char __user
*buf
, size_t count
, loff_t
*ppos
)
272 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
273 unsigned int currcons
= iminor(inode
);
276 long viewed
, attr
, size
, written
;
279 u16
*org0
= NULL
, *org
= NULL
;
286 /* Select the proper current console and verify
287 * sanity of the situation under the console lock.
289 acquire_console_sem();
291 attr
= (currcons
& 128);
292 currcons
= (currcons
& 127);
295 currcons
= fg_console
;
302 if (!vc_cons_allocated(currcons
))
304 vc
= vc_cons
[currcons
].d
;
306 size
= vcs_size(inode
);
308 if (pos
< 0 || pos
> size
)
310 if (count
> size
- pos
)
314 long this_round
= count
;
318 if (this_round
> CON_BUF_SIZE
)
319 this_round
= CON_BUF_SIZE
;
321 /* Temporarily drop the console lock so that we can read
322 * in the write data from userspace safely.
324 release_console_sem();
325 ret
= copy_from_user(con_buf
, buf
, this_round
);
326 acquire_console_sem();
331 /* Abort loop if no data were copied. Otherwise
341 /* The vcs_size might have changed while we slept to grab
342 * the user buffer, so recheck.
343 * Return data written up to now on failure.
345 size
= vcs_size(inode
);
348 if (this_round
> size
- pos
)
349 this_round
= size
- pos
;
351 /* OK, now actually push the write to the console
352 * under the lock using the local kernel buffer.
356 orig_count
= this_round
;
357 maxcol
= vc
->vc_cols
;
360 org0
= org
= screen_pos(vc
, p
, viewed
);
364 while (this_round
> 0) {
365 unsigned char c
= *con_buf0
++;
369 (vcs_scr_readw(vc
, org
) & 0xff00) | c
, org
);
371 if (++col
== maxcol
) {
372 org
= screen_pos(vc
, p
, viewed
);
378 if (p
< HEADER_SIZE
) {
379 char header
[HEADER_SIZE
];
381 getconsxy(vc
, header
+ 2);
382 while (p
< HEADER_SIZE
&& this_round
> 0) {
384 header
[p
++] = *con_buf0
++;
387 putconsxy(vc
, header
+ 2);
390 col
= (p
/2) % maxcol
;
391 if (this_round
> 0) {
392 org0
= org
= screen_pos(vc
, p
/2, viewed
);
393 if ((p
& 1) && this_round
> 0) {
399 vcs_scr_writew(vc
, c
|
400 (vcs_scr_readw(vc
, org
) & 0xff00), org
);
402 vcs_scr_writew(vc
, (c
<< 8) |
403 (vcs_scr_readw(vc
, org
) & 0xff), org
);
407 if (++col
== maxcol
) {
408 org
= screen_pos(vc
, p
/2, viewed
);
415 while (this_round
> 1) {
418 w
= get_unaligned(((unsigned short *)con_buf0
));
419 vcs_scr_writew(vc
, w
, org
++);
422 if (++col
== maxcol
) {
423 org
= screen_pos(vc
, p
, viewed
);
428 if (this_round
> 0) {
433 vcs_scr_writew(vc
, (vcs_scr_readw(vc
, org
) & 0xff) | (c
<< 8), org
);
435 vcs_scr_writew(vc
, (vcs_scr_readw(vc
, org
) & 0xff00) | c
, org
);
440 written
+= orig_count
;
444 update_region(vc
, (unsigned long)(org0
), org
- org0
);
450 release_console_sem();
458 vcs_open(struct inode
*inode
, struct file
*filp
)
460 unsigned int currcons
= iminor(inode
) & 127;
461 if(currcons
&& !vc_cons_allocated(currcons
-1))
466 static const struct file_operations vcs_fops
= {
473 static struct class *vc_class
;
475 void vcs_make_sysfs(struct tty_struct
*tty
)
477 device_create(vc_class
, NULL
, MKDEV(VCS_MAJOR
, tty
->index
+ 1),
478 "vcs%u", tty
->index
+ 1);
479 device_create(vc_class
, NULL
, MKDEV(VCS_MAJOR
, tty
->index
+ 129),
480 "vcsa%u", tty
->index
+ 1);
483 void vcs_remove_sysfs(struct tty_struct
*tty
)
485 device_destroy(vc_class
, MKDEV(VCS_MAJOR
, tty
->index
+ 1));
486 device_destroy(vc_class
, MKDEV(VCS_MAJOR
, tty
->index
+ 129));
489 int __init
vcs_init(void)
491 if (register_chrdev(VCS_MAJOR
, "vcs", &vcs_fops
))
492 panic("unable to get major %d for vcs device", VCS_MAJOR
);
493 vc_class
= class_create(THIS_MODULE
, "vc");
495 device_create(vc_class
, NULL
, MKDEV(VCS_MAJOR
, 0), "vcs");
496 device_create(vc_class
, NULL
, MKDEV(VCS_MAJOR
, 128), "vcsa");