1 files changed, 644 insertions, 0 deletions

diff --git a/drivers/tty/vt/vc_screen.c b/drivers/tty/vt/vc_screen.c
new file mode 100644
index 000000000000..273ab44cc91d
--- /dev/null
+++ b/drivers/tty/vt/vc_screen.c
@@ -0,0 +1,644 @@
+/*
+ * 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/kernel.h>
+#include <linux/major.h>
+#include <linux/errno.h>
+#include <linux/tty.h>
+#include <linux/interrupt.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+#include <linux/mutex.h>
+#include <linux/vt_kern.h>
+#include <linux/selection.h>
+#include <linux/kbd_kern.h>
+#include <linux/console.h>
+#include <linux/device.h>
+#include <linux/smp_lock.h>
+#include <linux/sched.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/signal.h>
+#include <linux/slab.h>
+#include <linux/notifier.h>
+
+#include <asm/uaccess.h>
+#include <asm/byteorder.h>
+#include <asm/unaligned.h>
+
+#undef attr
+#undef org
+#undef addr
+#define HEADER_SIZE     4
+
+struct vcs_poll_data {
+        struct notifier_block notifier;
+        unsigned int cons_num;
+        bool seen_last_update;
+        wait_queue_head_t waitq;
+        struct fasync_struct *fasync;
+};
+
+static int
+vcs_notifier(struct notifier_block *nb, unsigned long code, void *_param)
+{
+        struct vt_notifier_param *param = _param;
+        struct vc_data *vc = param->vc;
+        struct vcs_poll_data *poll =
+                container_of(nb, struct vcs_poll_data, notifier);
+        int currcons = poll->cons_num;
+
+        if (code != VT_UPDATE)
+                return NOTIFY_DONE;
+
+        if (currcons == 0)
+                currcons = fg_console;
+        else
+                currcons--;
+        if (currcons != vc->vc_num)
+                return NOTIFY_DONE;
+
+        poll->seen_last_update = false;
+        wake_up_interruptible(&poll->waitq);
+        kill_fasync(&poll->fasync, SIGIO, POLL_IN);
+        return NOTIFY_OK;
+}
+
+static void
+vcs_poll_data_free(struct vcs_poll_data *poll)
+{
+        unregister_vt_notifier(&poll->notifier);
+        kfree(poll);
+}
+
+static struct vcs_poll_data *
+vcs_poll_data_get(struct file *file)
+{
+        struct vcs_poll_data *poll = file->private_data;
+
+        if (poll)
+                return poll;
+
+        poll = kzalloc(sizeof(*poll), GFP_KERNEL);
+        if (!poll)
+                return NULL;
+        poll->cons_num = iminor(file->f_path.dentry->d_inode) & 127;
+        init_waitqueue_head(&poll->waitq);
+        poll->notifier.notifier_call = vcs_notifier;
+        if (register_vt_notifier(&poll->notifier) != 0) {
+                kfree(poll);
+                return NULL;
+        }
+
+        /*
+         * This code may be called either through ->poll() or ->fasync().
+         * If we have two threads using the same file descriptor, they could
+         * both enter this function, both notice that the structure hasn't
+         * been allocated yet and go ahead allocating it in parallel, but
+         * only one of them must survive and be shared otherwise we'd leak
+         * memory with a dangling notifier callback.
+         */
+        spin_lock(&file->f_lock);
+        if (!file->private_data) {
+                file->private_data = poll;
+        } else {
+                /* someone else raced ahead of us */
+                vcs_poll_data_free(poll);
+                poll = file->private_data;
+        }
+        spin_unlock(&file->f_lock);
+
+        return poll;
+}
+
+static int
+vcs_size(struct inode *inode)
+{
+        int size;
+        int minor = iminor(inode);
+        int currcons = minor & 127;
+        struct vc_data *vc;
+
+        if (currcons == 0)
+                currcons = fg_console;
+        else
+                currcons--;
+        if (!vc_cons_allocated(currcons))
+                return -ENXIO;
+        vc = vc_cons[currcons].d;
+
+        size = vc->vc_rows * vc->vc_cols;
+
+        if (minor & 128)
+                size = 2*size + HEADER_SIZE;
+        return size;
+}
+
+static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
+{
+        int size;
+
+        mutex_lock(&con_buf_mtx);
+        size = vcs_size(file->f_path.dentry->d_inode);
+        switch (orig) {
+                default:
+                        mutex_unlock(&con_buf_mtx);
+                        return -EINVAL;
+                case 2:
+                        offset += size;
+                        break;
+                case 1:
+                        offset += file->f_pos;
+                case 0:
+                        break;
+        }
+        if (offset < 0 || offset > size) {
+                mutex_unlock(&con_buf_mtx);
+                return -EINVAL;
+        }
+        file->f_pos = offset;
+        mutex_unlock(&con_buf_mtx);
+        return file->f_pos;
+}
+
+
+static ssize_t
+vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+        struct inode *inode = file->f_path.dentry->d_inode;
+        unsigned int currcons = iminor(inode);
+        struct vc_data *vc;
+        struct vcs_poll_data *poll;
+        long pos;
+        long viewed, attr, read;
+        int col, maxcol;
+        unsigned short *org = NULL;
+        ssize_t ret;
+
+        mutex_lock(&con_buf_mtx);
+
+        pos = *ppos;
+
+        /* 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;
+        vc = vc_cons[currcons].d;
+
+        ret = -EINVAL;
+        if (pos < 0)
+                goto unlock_out;
+        poll = file->private_data;
+        if (count && poll)
+                poll->seen_last_update = true;
+        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 = vc->vc_cols;
+                if (!attr) {
+                        org = screen_pos(vc, p, viewed);
+                        col = p % maxcol;
+                        p += maxcol - col;
+                        while (this_round-- > 0) {
+                                *con_buf0++ = (vcs_scr_readw(vc, org++) & 0xff);
+                                if (++col == maxcol) {
+                                        org = screen_pos(vc, p, viewed);
+                                        col = 0;
+                                        p += maxcol;
+                                }
+                        }
+                } else {
+                        if (p < HEADER_SIZE) {
+                                size_t tmp_count;
+
+                                con_buf0[0] = (char)vc->vc_rows;
+                                con_buf0[1] = (char)vc->vc_cols;
+                                getconsxy(vc, 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(vc, 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(vc, org++);
+                                        this_round --;
+                                        if (++col == maxcol) {
+                                                org = screen_pos(vc, 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();
+        mutex_unlock(&con_buf_mtx);
+        return ret;
+}
+
+static ssize_t
+vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+{
+        struct inode *inode = file->f_path.dentry->d_inode;
+        unsigned int currcons = iminor(inode);
+        struct vc_data *vc;
+        long pos;
+        long viewed, attr, size, written;
+        char *con_buf0;
+        int col, maxcol;
+        u16 *org0 = NULL, *org = NULL;
+        size_t ret;
+
+        mutex_lock(&con_buf_mtx);
+
+        pos = *ppos;
+
+        /* 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;
+        vc = vc_cons[currcons].d;
+
+        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 = vc->vc_cols;
+                p = pos;
+                if (!attr) {
+                        org0 = org = screen_pos(vc, p, viewed);
+                        col = p % maxcol;
+                        p += maxcol - col;
+
+                        while (this_round > 0) {
+                                unsigned char c = *con_buf0++;
+
+                                this_round--;
+                                vcs_scr_writew(vc,
+                                               (vcs_scr_readw(vc, org) & 0xff00) | c, org);
+                                org++;
+                                if (++col == maxcol) {
+                                        org = screen_pos(vc, p, viewed);
+                                        col = 0;
+                                        p += maxcol;
+                                }
+                        }
+                } else {
+                        if (p < HEADER_SIZE) {
+                                char header[HEADER_SIZE];
+
+                                getconsxy(vc, header + 2);
+                                while (p < HEADER_SIZE && this_round > 0) {
+                                        this_round--;
+                                        header[p++] = *con_buf0++;
+                                }
+                                if (!viewed)
+                                        putconsxy(vc, header + 2);
+                        }
+                        p -= HEADER_SIZE;
+                        col = (p/2) % maxcol;
+                        if (this_round > 0) {
+                                org0 = org = screen_pos(vc, p/2, viewed);
+                                if ((p & 1) && this_round > 0) {
+                                        char c;
+
+                                        this_round--;
+                                        c = *con_buf0++;
+#ifdef __BIG_ENDIAN
+                                        vcs_scr_writew(vc, c |
+                                             (vcs_scr_readw(vc, org) & 0xff00), org);
+#else
+                                        vcs_scr_writew(vc, (c << 8) |
+                                             (vcs_scr_readw(vc, org) & 0xff), org);
+#endif
+                                        org++;
+                                        p++;
+                                        if (++col == maxcol) {
+                                                org = screen_pos(vc, p/2, viewed);
+                                                col = 0;
+                                        }
+                                }
+                                p /= 2;
+                                p += maxcol - col;
+                        }
+                        while (this_round > 1) {
+                                unsigned short w;
+
+                                w = get_unaligned(((unsigned short *)con_buf0));
+                                vcs_scr_writew(vc, w, org++);
+                                con_buf0 += 2;
+                                this_round -= 2;
+                                if (++col == maxcol) {
+                                        org = screen_pos(vc, p, viewed);
+                                        col = 0;
+                                        p += maxcol;
+                                }
+                        }
+                        if (this_round > 0) {
+                                unsigned char c;
+
+                                c = *con_buf0++;
+#ifdef __BIG_ENDIAN
+                                vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) | (c << 8), org);
+#else
+                                vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) | c, org);
+#endif
+                        }
+                }
+                count -= orig_count;
+                written += orig_count;
+                buf += orig_count;
+                pos += orig_count;
+                if (org0)
+                        update_region(vc, (unsigned long)(org0), org - org0);
+        }
+        *ppos += written;
+        ret = written;
+        if (written)
+                vcs_scr_updated(vc);
+
+unlock_out:
+        release_console_sem();
+
+        mutex_unlock(&con_buf_mtx);
+
+        return ret;
+}
+
+static unsigned int
+vcs_poll(struct file *file, poll_table *wait)
+{
+        struct vcs_poll_data *poll = vcs_poll_data_get(file);
+        int ret = 0;
+
+        if (poll) {
+                poll_wait(file, &poll->waitq, wait);
+                if (!poll->seen_last_update)
+                        ret = POLLIN | POLLRDNORM;
+        }
+        return ret;
+}
+
+static int
+vcs_fasync(int fd, struct file *file, int on)
+{
+        struct vcs_poll_data *poll = file->private_data;
+
+        if (!poll) {
+                /* don't allocate anything if all we want is disable fasync */
+                if (!on)
+                        return 0;
+                poll = vcs_poll_data_get(file);
+                if (!poll)
+                        return -ENOMEM;
+        }
+
+        return fasync_helper(fd, file, on, &poll->fasync);
+}
+
+static int
+vcs_open(struct inode *inode, struct file *filp)
+{
+        unsigned int currcons = iminor(inode) & 127;
+        int ret = 0;
+        
+        tty_lock();
+        if(currcons && !vc_cons_allocated(currcons-1))
+                ret = -ENXIO;
+        tty_unlock();
+        return ret;
+}
+
+static int vcs_release(struct inode *inode, struct file *file)
+{
+        struct vcs_poll_data *poll = file->private_data;
+
+        if (poll)
+                vcs_poll_data_free(poll);
+        return 0;
+}
+
+static const struct file_operations vcs_fops = {
+        .llseek         = vcs_lseek,
+        .read           = vcs_read,
+        .write          = vcs_write,
+        .poll           = vcs_poll,
+        .fasync         = vcs_fasync,
+        .open           = vcs_open,
+        .release        = vcs_release,
+};
+
+static struct class *vc_class;
+
+void vcs_make_sysfs(int index)
+{
+        device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL,
+                      "vcs%u", index + 1);
+        device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL,
+                      "vcsa%u", index + 1);
+}
+
+void vcs_remove_sysfs(int index)
+{
+        device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1));
+        device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129));
+}
+
+int __init vcs_init(void)
+{
+        unsigned int i;
+
+        if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
+                panic("unable to get major %d for vcs device", VCS_MAJOR);
+        vc_class = class_create(THIS_MODULE, "vc");
+
+        device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs");
+        device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa");
+        for (i = 0; i < MIN_NR_CONSOLES; i++)
+                vcs_make_sysfs(i);
+        return 0;
+}