/* * 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/vt_kern.h> #include <linux/selection.h> #include <linux/kbd_kern.h> #include <linux/console.h> #include <linux/smp_lock.h> #include <linux/device.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 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; down(&con_buf_sem); size = vcs_size(file->f_path.dentry->d_inode); switch (orig) { default: up(&con_buf_sem); return -EINVAL; case 2: offset += size; break; case 1: offset += file->f_pos; case 0: break; } if (offset < 0 || offset > size) { up(&con_buf_sem); return -EINVAL; } file->f_pos = offset; up(&con_buf_sem); 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; long pos; long viewed, attr, read; int col, maxcol; unsigned short *org = NULL; ssize_t ret; down(&con_buf_sem); 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; 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(); up(&con_buf_sem); 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; down(&con_buf_sem); 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; unlock_out: release_console_sem(); up(&con_buf_sem); return ret; } static int vcs_open(struct inode *inode, struct file *filp) { unsigned int currcons = iminor(inode) & 127; if(currcons && !vc_cons_allocated(currcons-1)) return -ENXIO; return 0; } static const struct file_operations vcs_fops = { .llseek = vcs_lseek, .read = vcs_read, .write = vcs_write, .open = vcs_open, }; static struct class *vc_class; void vcs_make_sysfs(struct tty_struct *tty) { device_create(vc_class, NULL, MKDEV(VCS_MAJOR, tty->index + 1), "vcs%u", tty->index + 1); device_create(vc_class, NULL, MKDEV(VCS_MAJOR, tty->index + 129), "vcsa%u", tty->index + 1); } void vcs_remove_sysfs(struct tty_struct *tty) { device_destroy(vc_class, MKDEV(VCS_MAJOR, tty->index + 1)); device_destroy(vc_class, MKDEV(VCS_MAJOR, tty->index + 129)); } int __init vcs_init(void) { 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), "vcs"); device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), "vcsa"); return 0; }