/* * 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 49 vcs_size(struct inode *inode) { int size; int currcons = MINOR(inode->i_rdev) & 127; 53 if (currcons == 0) currcons = fg_console; 55 else currcons--; 57 if (!vc_cons_allocated(currcons)) 58 return -ENXIO; size = video_num_lines * video_num_columns; 62 if (MINOR(inode->i_rdev) & 128) size = 2*size + HEADER_SIZE; 64 return size; } 67 static loff_t vcs_lseek(struct file *file, loff_t offset, int orig) { int size = vcs_size(file->f_dentry->d_inode); 71 switch (orig) { 72 default: 73 return -EINVAL; 74 case 2: offset += size; 76 break; 77 case 1: offset += file->f_pos; 79 case 0: 80 break; } 82 if (offset < 0 || offset > size) 83 return -EINVAL; file->f_pos = offset; 85 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 97 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. */ 112 spin_lock_irq(&console_lock); attr = (currcons & 128); currcons = (currcons & 127); 116 if (currcons == 0) { currcons = fg_console; viewed = 1; 119 } else { currcons--; viewed = 0; } ret = -ENXIO; 124 if (!vc_cons_allocated(currcons)) 125 goto unlock_out; ret = -EINVAL; 128 if (pos < 0) 129 goto unlock_out; read = 0; ret = 0; 132 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); 143 if (pos >= size) 144 break; 145 if (count > size - pos) count = size - pos; this_round = count; 149 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; 160 if (!attr) { org = screen_pos(currcons, p, viewed); col = p % maxcol; p += maxcol - col; 164 while (this_round-- > 0) { *con_buf0++ = (vcs_scr_readw(currcons, org++) & 0xff); 166 if (++col == maxcol) { org = screen_pos(currcons, p, viewed); col = 0; p += maxcol; } } 172 } else { 173 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; 182 if (this_round > CON_BUF_SIZE) { this_round = CON_BUF_SIZE; orig_count = this_round - p; } tmp_count = HEADER_SIZE; 188 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... */ 196 } 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++; 202 if (this_round < CON_BUF_SIZE) this_round++; 204 else orig_count--; } 207 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; 223 while (this_round) { *tmp_buf++ = vcs_scr_readw(currcons, org++); this_round --; 226 if (++col == maxcol) { org = screen_pos(currcons, p, viewed); col = 0; p += maxcol; } } } } /* Finally, temporarily drop the console lock and push * all the data to userspace from our temporary buffer. */ 239 spin_unlock_irq(&console_lock); ret = copy_to_user(buf, con_buf_start, orig_count); 241 spin_lock_irq(&console_lock); 243 if (ret) { read += (orig_count - ret); ret = -EFAULT; 246 break; } buf += orig_count; pos += orig_count; read += orig_count; count -= orig_count; } *ppos += read; 254 if (read) ret = read; unlock_out: 257 spin_unlock_irq(&console_lock); up(&con_buf_sem); 259 return ret; } static ssize_t 263 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. */ 279 spin_lock_irq(&console_lock); attr = (currcons & 128); currcons = (currcons & 127); 284 if (currcons == 0) { currcons = fg_console; viewed = 1; 287 } else { currcons--; viewed = 0; } ret = -ENXIO; 292 if (!vc_cons_allocated(currcons)) 293 goto unlock_out; size = vcs_size(inode); ret = -EINVAL; 297 if (pos < 0 || pos > size) 298 goto unlock_out; 299 if (count > size - pos) count = size - pos; written = 0; 302 while (count) { long this_round = count; size_t orig_count; long p; 307 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. */ 313 spin_unlock_irq(&console_lock); ret = copy_from_user(con_buf, buf, this_round); 315 spin_lock_irq(&console_lock); 317 if (ret) { this_round -= ret; 319 if (!this_round) { /* Abort loop if no data were copied. Otherwise * fail with -EFAULT. */ 323 if (written) 324 break; ret = -EFAULT; 326 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); 335 if (pos >= size) 336 break; 337 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; 348 if (!attr) { org0 = org = screen_pos(currcons, p, viewed); col = p % maxcol; p += maxcol - col; 353 while (this_round > 0) { unsigned char c = *con_buf0++; this_round--; vcs_scr_writew(currcons, (vcs_scr_readw(currcons, org) & 0xff00) | c, org); org++; 360 if (++col == maxcol) { org = screen_pos(currcons, p, viewed); col = 0; p += maxcol; } } 366 } else { 367 if (p < HEADER_SIZE) { char header[HEADER_SIZE]; getconsxy(currcons, header + 2); 371 while (p < HEADER_SIZE && this_round > 0) { this_round--; header[p++] = *con_buf0++; } 375 if (!viewed) putconsxy(currcons, header + 2); } p -= HEADER_SIZE; col = (p/2) % maxcol; 380 if (this_round > 0) { org0 = org = screen_pos(currcons, p/2, viewed); 382 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++; 396 if (++col == maxcol) { org = screen_pos(currcons, p/2, viewed); col = 0; } } p /= 2; p += maxcol - col; } 404 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; 411 if (++col == maxcol) { org = screen_pos(currcons, p, viewed); col = 0; p += maxcol; } } 417 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; 432 if (org0) update_region(currcons, (unsigned long)(org0), org-org0); } *ppos += written; ret = written; unlock_out: 439 spin_unlock_irq(&console_lock); up(&con_buf_sem); 443 return ret; } static int 447 vcs_open(struct inode *inode, struct file *filp) { unsigned int currcons = (MINOR(inode->i_rdev) & 127); 450 if(currcons && !vc_cons_allocated(currcons-1)) 451 return -ENXIO; 452 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; 464 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 */ } 489 int __init vcs_init(void) { int error; error = devfs_register_chrdev(VCS_MAJOR, "vcs", &vcs_fops); 495 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); 506 return error; }