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