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/smp_lock.h>
36 #include <linux/device.h>
37 #include <asm/uaccess.h>
38 #include <asm/byteorder.h>
39 #include <asm/unaligned.h>
47 vcs_size(struct inode
*inode
)
50 int minor
= iminor(inode
);
51 int currcons
= minor
& 127;
55 currcons
= fg_console
;
58 if (!vc_cons_allocated(currcons
))
60 vc
= vc_cons
[currcons
].d
;
62 size
= vc
->vc_rows
* vc
->vc_cols
;
65 size
= 2*size
+ HEADER_SIZE
;
69 static loff_t
vcs_lseek(struct file
*file
, loff_t offset
, int orig
)
74 size
= vcs_size(file
->f_path
.dentry
->d_inode
);
83 offset
+= file
->f_pos
;
87 if (offset
< 0 || offset
> size
) {
98 vcs_read(struct file
*file
, char __user
*buf
, size_t count
, loff_t
*ppos
)
100 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
101 unsigned int currcons
= iminor(inode
);
104 long viewed
, attr
, read
;
106 unsigned short *org
= NULL
;
113 /* Select the proper current console and verify
114 * sanity of the situation under the console lock.
116 acquire_console_sem();
118 attr
= (currcons
& 128);
119 currcons
= (currcons
& 127);
121 currcons
= fg_console
;
128 if (!vc_cons_allocated(currcons
))
130 vc
= vc_cons
[currcons
].d
;
138 char *con_buf0
, *con_buf_start
;
139 long this_round
, size
;
143 /* Check whether we are above size each round,
144 * as copy_to_user at the end of this loop
147 size
= vcs_size(inode
);
150 if (count
> size
- pos
)
154 if (this_round
> CON_BUF_SIZE
)
155 this_round
= CON_BUF_SIZE
;
157 /* Perform the whole read into the local con_buf.
158 * Then we can drop the console spinlock and safely
159 * attempt to move it to userspace.
162 con_buf_start
= con_buf0
= con_buf
;
163 orig_count
= this_round
;
164 maxcol
= vc
->vc_cols
;
166 org
= screen_pos(vc
, p
, viewed
);
169 while (this_round
-- > 0) {
170 *con_buf0
++ = (vcs_scr_readw(vc
, org
++) & 0xff);
171 if (++col
== maxcol
) {
172 org
= screen_pos(vc
, p
, viewed
);
178 if (p
< HEADER_SIZE
) {
181 con_buf0
[0] = (char)vc
->vc_rows
;
182 con_buf0
[1] = (char)vc
->vc_cols
;
183 getconsxy(vc
, con_buf0
+ 2);
187 if (this_round
> CON_BUF_SIZE
) {
188 this_round
= CON_BUF_SIZE
;
189 orig_count
= this_round
- p
;
192 tmp_count
= HEADER_SIZE
;
193 if (tmp_count
> this_round
)
194 tmp_count
= this_round
;
196 /* Advance state pointers and move on. */
197 this_round
-= tmp_count
;
199 con_buf0
= con_buf
+ HEADER_SIZE
;
200 /* If this_round >= 0, then p is even... */
202 /* Skip first byte for output if start address is odd
203 * Update region sizes up/down depending on free
207 if (this_round
< CON_BUF_SIZE
)
212 if (this_round
> 0) {
213 unsigned short *tmp_buf
= (unsigned short *)con_buf0
;
219 org
= screen_pos(vc
, p
, viewed
);
222 /* Buffer has even length, so we can always copy
223 * character + attribute. We do not copy last byte
224 * to userspace if this_round is odd.
226 this_round
= (this_round
+ 1) >> 1;
229 *tmp_buf
++ = vcs_scr_readw(vc
, org
++);
231 if (++col
== maxcol
) {
232 org
= screen_pos(vc
, p
, viewed
);
240 /* Finally, release the console semaphore while we push
241 * all the data to userspace from our temporary buffer.
243 * AKPM: Even though it's a semaphore, we should drop it because
244 * the pagefault handling code may want to call printk().
247 release_console_sem();
248 ret
= copy_to_user(buf
, con_buf_start
, orig_count
);
249 acquire_console_sem();
252 read
+= (orig_count
- ret
);
265 release_console_sem();
271 vcs_write(struct file
*file
, const char __user
*buf
, size_t count
, loff_t
*ppos
)
273 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
274 unsigned int currcons
= iminor(inode
);
277 long viewed
, attr
, size
, written
;
280 u16
*org0
= NULL
, *org
= NULL
;
287 /* Select the proper current console and verify
288 * sanity of the situation under the console lock.
290 acquire_console_sem();
292 attr
= (currcons
& 128);
293 currcons
= (currcons
& 127);
296 currcons
= fg_console
;
303 if (!vc_cons_allocated(currcons
))
305 vc
= vc_cons
[currcons
].d
;
307 size
= vcs_size(inode
);
309 if (pos
< 0 || pos
> size
)
311 if (count
> size
- pos
)
315 long this_round
= count
;
319 if (this_round
> CON_BUF_SIZE
)
320 this_round
= CON_BUF_SIZE
;
322 /* Temporarily drop the console lock so that we can read
323 * in the write data from userspace safely.
325 release_console_sem();
326 ret
= copy_from_user(con_buf
, buf
, this_round
);
327 acquire_console_sem();
332 /* Abort loop if no data were copied. Otherwise
342 /* The vcs_size might have changed while we slept to grab
343 * the user buffer, so recheck.
344 * Return data written up to now on failure.
346 size
= vcs_size(inode
);
349 if (this_round
> size
- pos
)
350 this_round
= size
- pos
;
352 /* OK, now actually push the write to the console
353 * under the lock using the local kernel buffer.
357 orig_count
= this_round
;
358 maxcol
= vc
->vc_cols
;
361 org0
= org
= screen_pos(vc
, p
, viewed
);
365 while (this_round
> 0) {
366 unsigned char c
= *con_buf0
++;
370 (vcs_scr_readw(vc
, org
) & 0xff00) | c
, org
);
372 if (++col
== maxcol
) {
373 org
= screen_pos(vc
, p
, viewed
);
379 if (p
< HEADER_SIZE
) {
380 char header
[HEADER_SIZE
];
382 getconsxy(vc
, header
+ 2);
383 while (p
< HEADER_SIZE
&& this_round
> 0) {
385 header
[p
++] = *con_buf0
++;
388 putconsxy(vc
, header
+ 2);
391 col
= (p
/2) % maxcol
;
392 if (this_round
> 0) {
393 org0
= org
= screen_pos(vc
, p
/2, viewed
);
394 if ((p
& 1) && this_round
> 0) {
400 vcs_scr_writew(vc
, c
|
401 (vcs_scr_readw(vc
, org
) & 0xff00), org
);
403 vcs_scr_writew(vc
, (c
<< 8) |
404 (vcs_scr_readw(vc
, org
) & 0xff), org
);
408 if (++col
== maxcol
) {
409 org
= screen_pos(vc
, p
/2, viewed
);
416 while (this_round
> 1) {
419 w
= get_unaligned(((unsigned short *)con_buf0
));
420 vcs_scr_writew(vc
, w
, org
++);
423 if (++col
== maxcol
) {
424 org
= screen_pos(vc
, p
, viewed
);
429 if (this_round
> 0) {
434 vcs_scr_writew(vc
, (vcs_scr_readw(vc
, org
) & 0xff) | (c
<< 8), org
);
436 vcs_scr_writew(vc
, (vcs_scr_readw(vc
, org
) & 0xff00) | c
, org
);
441 written
+= orig_count
;
445 update_region(vc
, (unsigned long)(org0
), org
- org0
);
451 release_console_sem();
459 vcs_open(struct inode
*inode
, struct file
*filp
)
461 unsigned int currcons
= iminor(inode
) & 127;
462 if(currcons
&& !vc_cons_allocated(currcons
-1))
467 static const struct file_operations vcs_fops
= {
474 static struct class *vc_class
;
476 void vcs_make_sysfs(struct tty_struct
*tty
)
478 device_create(vc_class
, NULL
, MKDEV(VCS_MAJOR
, tty
->index
+ 1),
479 "vcs%u", tty
->index
+ 1);
480 device_create(vc_class
, NULL
, MKDEV(VCS_MAJOR
, tty
->index
+ 129),
481 "vcsa%u", tty
->index
+ 1);
484 void vcs_remove_sysfs(struct tty_struct
*tty
)
486 device_destroy(vc_class
, MKDEV(VCS_MAJOR
, tty
->index
+ 1));
487 device_destroy(vc_class
, MKDEV(VCS_MAJOR
, tty
->index
+ 129));
490 int __init
vcs_init(void)
492 if (register_chrdev(VCS_MAJOR
, "vcs", &vcs_fops
))
493 panic("unable to get major %d for vcs device", VCS_MAJOR
);
494 vc_class
= class_create(THIS_MODULE
, "vc");
496 device_create(vc_class
, NULL
, MKDEV(VCS_MAJOR
, 0), "vcs");
497 device_create(vc_class
, NULL
, MKDEV(VCS_MAJOR
, 128), "vcsa");
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