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/*
* linux/drivers/char/vc_screen.c
*
* Provide access to virtual console memory.
* /dev/vcs0: the screen as it is being viewed right now (possibly scrolled)
* /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63)
* [minor: N]
*
* /dev/vcsaN: idem, but including attributes, and prefixed with
* the 4 bytes lines,columns,x,y (as screendump used to give).
* Attribute/character pair is in native endianity.
* [minor: N+128]
*
* This replaces screendump and part of selection, so that the system
* administrator can control access using file system permissions.
*
* aeb@cwi.nl - efter Friedas begravelse - 950211
*
* machek@k332.feld.cvut.cz - modified not to send characters to wrong console
* - fixed some fatal off-by-one bugs (0-- no longer == -1 -> looping and looping and looping...)
* - making it shorter - scr_readw are macros which expand in PRETTY long code
*/
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/errno.h>
#include <linux/tty.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/vt_kern.h>
#include <linux/console_struct.h>
#include <linux/selection.h>
#include <linux/kbd_kern.h>
#include <linux/console.h>
#include <asm/uaccess.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>
#undef attr
#undef org
#undef addr
#define HEADER_SIZE 4
static int
vcs_size(struct inode *inode)
{
int size;
int currcons = MINOR(inode->i_rdev) & 127;
if (currcons == 0)
currcons = fg_console;
else
currcons--;
if (!vc_cons_allocated(currcons))
return -ENXIO;
size = video_num_lines * video_num_columns;
if (MINOR(inode->i_rdev) & 128)
size = 2*size + HEADER_SIZE;
return size;
}
static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
{
int size = vcs_size(file->f_dentry->d_inode);
switch (orig) {
default:
return -EINVAL;
case 2:
offset += size;
break;
case 1:
offset += file->f_pos;
case 0:
break;
}
if (offset < 0 || offset > size)
return -EINVAL;
file->f_pos = offset;
return file->f_pos;
}
/* We share this temporary buffer with the console write code
* so that we can easily avoid touching user space while holding the
* console spinlock.
*/
extern char con_buf[PAGE_SIZE];
#define CON_BUF_SIZE PAGE_SIZE
extern struct semaphore con_buf_sem;
static ssize_t
vcs_read(struct file *file, char *buf, size_t count, loff_t *ppos)
{
struct inode *inode = file->f_dentry->d_inode;
unsigned int currcons = MINOR(inode->i_rdev);
long pos = *ppos;
long viewed, attr, read;
int col, maxcol;
unsigned short *org = NULL;
ssize_t ret;
down(&con_buf_sem);
/* Select the proper current console and verify
* sanity of the situation under the console lock.
*/
acquire_console_sem();
attr = (currcons & 128);
currcons = (currcons & 127);
if (currcons == 0) {
currcons = fg_console;
viewed = 1;
} else {
currcons--;
viewed = 0;
}
ret = -ENXIO;
if (!vc_cons_allocated(currcons))
goto unlock_out;
ret = -EINVAL;
if (pos < 0)
goto unlock_out;
read = 0;
ret = 0;
while (count) {
char *con_buf0, *con_buf_start;
long this_round, size;
ssize_t orig_count;
long p = pos;
/* Check whether we are above size each round,
* as copy_to_user at the end of this loop
* could sleep.
*/
size = vcs_size(inode);
if (pos >= size)
break;
if (count > size - pos)
count = size - pos;
this_round = count;
if (this_round > CON_BUF_SIZE)
this_round = CON_BUF_SIZE;
/* Perform the whole read into the local con_buf.
* Then we can drop the console spinlock and safely
* attempt to move it to userspace.
*/
con_buf_start = con_buf0 = con_buf;
orig_count = this_round;
maxcol = video_num_columns;
if (!attr) {
org = screen_pos(currcons, p, viewed);
col = p % maxcol;
p += maxcol - col;
while (this_round-- > 0) {
*con_buf0++ = (vcs_scr_readw(currcons, org++) & 0xff);
if (++col == maxcol) {
org = screen_pos(currcons, p, viewed);
col = 0;
p += maxcol;
}
}
} else {
if (p < HEADER_SIZE) {
size_t tmp_count;
con_buf0[0] = (char) video_num_lines;
con_buf0[1] = (char) video_num_columns;
getconsxy(currcons, con_buf0 + 2);
con_buf_start += p;
this_round += p;
if (this_round > CON_BUF_SIZE) {
this_round = CON_BUF_SIZE;
orig_count = this_round - p;
}
tmp_count = HEADER_SIZE;
if (tmp_count > this_round)
tmp_count = this_round;
/* Advance state pointers and move on. */
this_round -= tmp_count;
p = HEADER_SIZE;
con_buf0 = con_buf + HEADER_SIZE;
/* If this_round >= 0, then p is even... */
} else if (p & 1) {
/* Skip first byte for output if start address is odd
* Update region sizes up/down depending on free
* space in buffer.
*/
con_buf_start++;
if (this_round < CON_BUF_SIZE)
this_round++;
else
orig_count--;
}
if (this_round > 0) {
unsigned short *tmp_buf = (unsigned short *)con_buf0;
p -= HEADER_SIZE;
p /= 2;
col = p % maxcol;
org = screen_pos(currcons, p, viewed);
p += maxcol - col;
/* Buffer has even length, so we can always copy
* character + attribute. We do not copy last byte
* to userspace if this_round is odd.
*/
this_round = (this_round + 1) >> 1;
while (this_round) {
*tmp_buf++ = vcs_scr_readw(currcons, org++);
this_round --;
if (++col == maxcol) {
org = screen_pos(currcons, p, viewed);
col = 0;
p += maxcol;
}
}
}
}
/* Finally, release the console semaphore while we push
* all the data to userspace from our temporary buffer.
*
* AKPM: Even though it's a semaphore, we should drop it because
* the pagefault handling code may want to call printk().
*/
release_console_sem();
ret = copy_to_user(buf, con_buf_start, orig_count);
acquire_console_sem();
if (ret) {
read += (orig_count - ret);
ret = -EFAULT;
break;
}
buf += orig_count;
pos += orig_count;
read += orig_count;
count -= orig_count;
}
*ppos += read;
if (read)
ret = read;
unlock_out:
release_console_sem();
up(&con_buf_sem);
return ret;
}
static ssize_t
vcs_write(struct file *file, const char *buf, size_t count, loff_t *ppos)
{
struct inode *inode = file->f_dentry->d_inode;
unsigned int currcons = MINOR(inode->i_rdev);
long pos = *ppos;
long viewed, attr, size, written;
char *con_buf0;
int col, maxcol;
u16 *org0 = NULL, *org = NULL;
size_t ret;
down(&con_buf_sem);
/* Select the proper current console and verify
* sanity of the situation under the console lock.
*/
acquire_console_sem();
attr = (currcons & 128);
currcons = (currcons & 127);
if (currcons == 0) {
currcons = fg_console;
viewed = 1;
} else {
currcons--;
viewed = 0;
}
ret = -ENXIO;
if (!vc_cons_allocated(currcons))
goto unlock_out;
size = vcs_size(inode);
ret = -EINVAL;
if (pos < 0 || pos > size)
goto unlock_out;
if (count > size - pos)
count = size - pos;
written = 0;
while (count) {
long this_round = count;
size_t orig_count;
long p;
if (this_round > CON_BUF_SIZE)
this_round = CON_BUF_SIZE;
/* Temporarily drop the console lock so that we can read
* in the write data from userspace safely.
*/
release_console_sem();
ret = copy_from_user(con_buf, buf, this_round);
acquire_console_sem();
if (ret) {
this_round -= ret;
if (!this_round) {
/* Abort loop if no data were copied. Otherwise
* fail with -EFAULT.
*/
if (written)
break;
ret = -EFAULT;
goto unlock_out;
}
}
/* The vcs_size might have changed while we slept to grab
* the user buffer, so recheck.
* Return data written up to now on failure.
*/
size = vcs_size(inode);
if (pos >= size)
break;
if (this_round > size - pos)
this_round = size - pos;
/* OK, now actually push the write to the console
* under the lock using the local kernel buffer.
*/
con_buf0 = con_buf;
orig_count = this_round;
maxcol = video_num_columns;
p = pos;
if (!attr) {
org0 = org = screen_pos(currcons, p, viewed);
col = p % maxcol;
p += maxcol - col;
while (this_round > 0) {
unsigned char c = *con_buf0++;
this_round--;
vcs_scr_writew(currcons,
(vcs_scr_readw(currcons, org) & 0xff00) | c, org);
org++;
if (++col == maxcol) {
org = screen_pos(currcons, p, viewed);
col = 0;
p += maxcol;
}
}
} else {
if (p < HEADER_SIZE) {
char header[HEADER_SIZE];
getconsxy(currcons, header + 2);
while (p < HEADER_SIZE && this_round > 0) {
this_round--;
header[p++] = *con_buf0++;
}
if (!viewed)
putconsxy(currcons, header + 2);
}
p -= HEADER_SIZE;
col = (p/2) % maxcol;
if (this_round > 0) {
org0 = org = screen_pos(currcons, p/2, viewed);
if ((p & 1) && this_round > 0) {
char c;
this_round--;
c = *con_buf0++;
#ifdef __BIG_ENDIAN
vcs_scr_writew(currcons, c |
(vcs_scr_readw(currcons, org) & 0xff00), org);
#else
vcs_scr_writew(currcons, (c << 8) |
(vcs_scr_readw(currcons, org) & 0xff), org);
#endif
org++;
p++;
if (++col == maxcol) {
org = screen_pos(currcons, p/2, viewed);
col = 0;
}
}
p /= 2;
p += maxcol - col;
}
while (this_round > 1) {
unsigned short w;
w = get_unaligned(((const unsigned short *)con_buf0));
vcs_scr_writew(currcons, w, org++);
con_buf0 += 2;
this_round -= 2;
if (++col == maxcol) {
org = screen_pos(currcons, p, viewed);
col = 0;
p += maxcol;
}
}
if (this_round > 0) {
unsigned char c;
c = *con_buf0++;
#ifdef __BIG_ENDIAN
vcs_scr_writew(currcons, (vcs_scr_readw(currcons, org) & 0xff) | (c << 8), org);
#else
vcs_scr_writew(currcons, (vcs_scr_readw(currcons, org) & 0xff00) | c, org);
#endif
}
}
count -= orig_count;
written += orig_count;
buf += orig_count;
pos += orig_count;
if (org0)
update_region(currcons, (unsigned long)(org0), org-org0);
}
*ppos += written;
ret = written;
unlock_out:
release_console_sem();
up(&con_buf_sem);
return ret;
}
static int
vcs_open(struct inode *inode, struct file *filp)
{
unsigned int currcons = (MINOR(inode->i_rdev) & 127);
if(currcons && !vc_cons_allocated(currcons-1))
return -ENXIO;
return 0;
}
static struct file_operations vcs_fops = {
llseek: vcs_lseek,
read: vcs_read,
write: vcs_write,
open: vcs_open,
};
static devfs_handle_t devfs_handle;
void vcs_make_devfs (unsigned int index, int unregister)
{
#ifdef CONFIG_DEVFS_FS
char name[8];
sprintf (name, "a%u", index + 1);
if (unregister)
{
devfs_unregister ( devfs_find_handle (devfs_handle, name + 1, 0, 0,
DEVFS_SPECIAL_CHR, 0) );
devfs_unregister ( devfs_find_handle (devfs_handle, name, 0, 0,
DEVFS_SPECIAL_CHR, 0) );
}
else
{
devfs_register (devfs_handle, name + 1, DEVFS_FL_DEFAULT,
VCS_MAJOR, index + 1,
S_IFCHR | S_IRUSR | S_IWUSR, &vcs_fops, NULL);
devfs_register (devfs_handle, name, DEVFS_FL_DEFAULT,
VCS_MAJOR, index + 129,
S_IFCHR | S_IRUSR | S_IWUSR, &vcs_fops, NULL);
}
#endif /* CONFIG_DEVFS_FS */
}
int __init vcs_init(void)
{
int error;
error = devfs_register_chrdev(VCS_MAJOR, "vcs", &vcs_fops);
if (error)
printk("unable to get major %d for vcs device", VCS_MAJOR);
devfs_handle = devfs_mk_dir (NULL, "vcc", NULL);
devfs_register (devfs_handle, "0", DEVFS_FL_DEFAULT,
VCS_MAJOR, 0,
S_IFCHR | S_IRUSR | S_IWUSR, &vcs_fops, NULL);
devfs_register (devfs_handle, "a", DEVFS_FL_DEFAULT,
VCS_MAJOR, 128,
S_IFCHR | S_IRUSR | S_IWUSR, &vcs_fops, NULL);
return error;
}
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