1/* 2 * linux/drivers/char/vc_screen.c 3 * 4 * Provide access to virtual console memory. 5 * /dev/vcs0: the screen as it is being viewed right now (possibly scrolled) 6 * /dev/vcsN: the screen of /dev/ttyN (1 <= N <= 63) 7 * [minor: N] 8 * 9 * /dev/vcsaN: idem, but including attributes, and prefixed with 10 * the 4 bytes lines,columns,x,y (as screendump used to give). 11 * Attribute/character pair is in native endianity. 12 * [minor: N+128] 13 * 14 * This replaces screendump and part of selection, so that the system 15 * administrator can control access using file system permissions. 16 * 17 * aeb@cwi.nl - efter Friedas begravelse - 950211 18 * 19 * machek@k332.feld.cvut.cz - modified not to send characters to wrong console 20 * - fixed some fatal off-by-one bugs (0-- no longer == -1 -> looping and looping and looping...) 21 * - making it shorter - scr_readw are macros which expand in PRETTY long code 22 */ 23 24#include <linux/kernel.h> 25#include <linux/major.h> 26#include <linux/errno.h> 27#include <linux/tty.h> 28#include <linux/interrupt.h> 29#include <linux/mm.h> 30#include <linux/init.h> 31#include <linux/mutex.h> 32#include <linux/vt_kern.h> 33#include <linux/selection.h> 34#include <linux/kbd_kern.h> 35#include <linux/console.h> 36#include <linux/device.h> 37#include <linux/smp_lock.h> 38 39#include <asm/uaccess.h> 40#include <asm/byteorder.h> 41#include <asm/unaligned.h> 42 43#undef attr 44#undef org 45#undef addr 46#define HEADER_SIZE 4 47 48static int 49vcs_size(struct inode *inode) 50{ 51 int size; 52 int minor = iminor(inode); 53 int currcons = minor & 127; 54 struct vc_data *vc; 55 56 if (currcons == 0) 57 currcons = fg_console; 58 else 59 currcons--; 60 if (!vc_cons_allocated(currcons)) 61 return -ENXIO; 62 vc = vc_cons[currcons].d; 63 64 size = vc->vc_rows * vc->vc_cols; 65 66 if (minor & 128) 67 size = 2*size + HEADER_SIZE; 68 return size; 69} 70 71static loff_t vcs_lseek(struct file *file, loff_t offset, int orig) 72{ 73 int size; 74 75 mutex_lock(&con_buf_mtx); 76 size = vcs_size(file->f_path.dentry->d_inode); 77 switch (orig) { 78 default: 79 mutex_unlock(&con_buf_mtx); 80 return -EINVAL; 81 case 2: 82 offset += size; 83 break; 84 case 1: 85 offset += file->f_pos; 86 case 0: 87 break; 88 } 89 if (offset < 0 || offset > size) { 90 mutex_unlock(&con_buf_mtx); 91 return -EINVAL; 92 } 93 file->f_pos = offset; 94 mutex_unlock(&con_buf_mtx); 95 return file->f_pos; 96} 97 98 99static ssize_t 100vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos) 101{ 102 struct inode *inode = file->f_path.dentry->d_inode; 103 unsigned int currcons = iminor(inode); 104 struct vc_data *vc; 105 long pos; 106 long viewed, attr, read; 107 int col, maxcol; 108 unsigned short *org = NULL; 109 ssize_t ret; 110 111 mutex_lock(&con_buf_mtx); 112 113 pos = *ppos; 114 115 /* Select the proper current console and verify 116 * sanity of the situation under the console lock. 117 */ 118 acquire_console_sem(); 119 120 attr = (currcons & 128); 121 currcons = (currcons & 127); 122 if (currcons == 0) { 123 currcons = fg_console; 124 viewed = 1; 125 } else { 126 currcons--; 127 viewed = 0; 128 } 129 ret = -ENXIO; 130 if (!vc_cons_allocated(currcons)) 131 goto unlock_out; 132 vc = vc_cons[currcons].d; 133 134 ret = -EINVAL; 135 if (pos < 0) 136 goto unlock_out; 137 read = 0; 138 ret = 0; 139 while (count) { 140 char *con_buf0, *con_buf_start; 141 long this_round, size; 142 ssize_t orig_count; 143 long p = pos; 144 145 /* Check whether we are above size each round, 146 * as copy_to_user at the end of this loop 147 * could sleep. 148 */ 149 size = vcs_size(inode); 150 if (pos >= size) 151 break; 152 if (count > size - pos) 153 count = size - pos; 154 155 this_round = count; 156 if (this_round > CON_BUF_SIZE) 157 this_round = CON_BUF_SIZE; 158 159 /* Perform the whole read into the local con_buf. 160 * Then we can drop the console spinlock and safely 161 * attempt to move it to userspace. 162 */ 163 164 con_buf_start = con_buf0 = con_buf; 165 orig_count = this_round; 166 maxcol = vc->vc_cols; 167 if (!attr) { 168 org = screen_pos(vc, p, viewed); 169 col = p % maxcol; 170 p += maxcol - col; 171 while (this_round-- > 0) { 172 *con_buf0++ = (vcs_scr_readw(vc, org++) & 0xff); 173 if (++col == maxcol) { 174 org = screen_pos(vc, p, viewed); 175 col = 0; 176 p += maxcol; 177 } 178 } 179 } else { 180 if (p < HEADER_SIZE) { 181 size_t tmp_count; 182 183 con_buf0[0] = (char)vc->vc_rows; 184 con_buf0[1] = (char)vc->vc_cols; 185 getconsxy(vc, con_buf0 + 2); 186 187 con_buf_start += p; 188 this_round += p; 189 if (this_round > CON_BUF_SIZE) { 190 this_round = CON_BUF_SIZE; 191 orig_count = this_round - p; 192 } 193 194 tmp_count = HEADER_SIZE; 195 if (tmp_count > this_round) 196 tmp_count = this_round; 197 198 /* Advance state pointers and move on. */ 199 this_round -= tmp_count; 200 p = HEADER_SIZE; 201 con_buf0 = con_buf + HEADER_SIZE; 202 /* If this_round >= 0, then p is even... */ 203 } else if (p & 1) { 204 /* Skip first byte for output if start address is odd 205 * Update region sizes up/down depending on free 206 * space in buffer. 207 */ 208 con_buf_start++; 209 if (this_round < CON_BUF_SIZE) 210 this_round++; 211 else 212 orig_count--; 213 } 214 if (this_round > 0) { 215 unsigned short *tmp_buf = (unsigned short *)con_buf0; 216 217 p -= HEADER_SIZE; 218 p /= 2; 219 col = p % maxcol; 220 221 org = screen_pos(vc, p, viewed); 222 p += maxcol - col; 223 224 /* Buffer has even length, so we can always copy 225 * character + attribute. We do not copy last byte 226 * to userspace if this_round is odd. 227 */ 228 this_round = (this_round + 1) >> 1; 229 230 while (this_round) { 231 *tmp_buf++ = vcs_scr_readw(vc, org++); 232 this_round --; 233 if (++col == maxcol) { 234 org = screen_pos(vc, p, viewed); 235 col = 0; 236 p += maxcol; 237 } 238 } 239 } 240 } 241 242 /* Finally, release the console semaphore while we push 243 * all the data to userspace from our temporary buffer. 244 * 245 * AKPM: Even though it's a semaphore, we should drop it because 246 * the pagefault handling code may want to call printk(). 247 */ 248 249 release_console_sem(); 250 ret = copy_to_user(buf, con_buf_start, orig_count); 251 acquire_console_sem(); 252 253 if (ret) { 254 read += (orig_count - ret); 255 ret = -EFAULT; 256 break; 257 } 258 buf += orig_count; 259 pos += orig_count; 260 read += orig_count; 261 count -= orig_count; 262 } 263 *ppos += read; 264 if (read) 265 ret = read; 266unlock_out: 267 release_console_sem(); 268 mutex_unlock(&con_buf_mtx); 269 return ret; 270} 271 272static ssize_t 273vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 274{ 275 struct inode *inode = file->f_path.dentry->d_inode; 276 unsigned int currcons = iminor(inode); 277 struct vc_data *vc; 278 long pos; 279 long viewed, attr, size, written; 280 char *con_buf0; 281 int col, maxcol; 282 u16 *org0 = NULL, *org = NULL; 283 size_t ret; 284 285 mutex_lock(&con_buf_mtx); 286 287 pos = *ppos; 288 289 /* Select the proper current console and verify 290 * sanity of the situation under the console lock. 291 */ 292 acquire_console_sem(); 293 294 attr = (currcons & 128); 295 currcons = (currcons & 127); 296 297 if (currcons == 0) { 298 currcons = fg_console; 299 viewed = 1; 300 } else { 301 currcons--; 302 viewed = 0; 303 } 304 ret = -ENXIO; 305 if (!vc_cons_allocated(currcons)) 306 goto unlock_out; 307 vc = vc_cons[currcons].d; 308 309 size = vcs_size(inode); 310 ret = -EINVAL; 311 if (pos < 0 || pos > size) 312 goto unlock_out; 313 if (count > size - pos) 314 count = size - pos; 315 written = 0; 316 while (count) { 317 long this_round = count; 318 size_t orig_count; 319 long p; 320 321 if (this_round > CON_BUF_SIZE) 322 this_round = CON_BUF_SIZE; 323 324 /* Temporarily drop the console lock so that we can read 325 * in the write data from userspace safely. 326 */ 327 release_console_sem(); 328 ret = copy_from_user(con_buf, buf, this_round); 329 acquire_console_sem(); 330 331 if (ret) { 332 this_round -= ret; 333 if (!this_round) { 334 /* Abort loop if no data were copied. Otherwise 335 * fail with -EFAULT. 336 */ 337 if (written) 338 break; 339 ret = -EFAULT; 340 goto unlock_out; 341 } 342 } 343 344 /* The vcs_size might have changed while we slept to grab 345 * the user buffer, so recheck. 346 * Return data written up to now on failure. 347 */ 348 size = vcs_size(inode); 349 if (pos >= size) 350 break; 351 if (this_round > size - pos) 352 this_round = size - pos; 353 354 /* OK, now actually push the write to the console 355 * under the lock using the local kernel buffer. 356 */ 357 358 con_buf0 = con_buf; 359 orig_count = this_round; 360 maxcol = vc->vc_cols; 361 p = pos; 362 if (!attr) { 363 org0 = org = screen_pos(vc, p, viewed); 364 col = p % maxcol; 365 p += maxcol - col; 366 367 while (this_round > 0) { 368 unsigned char c = *con_buf0++; 369 370 this_round--; 371 vcs_scr_writew(vc, 372 (vcs_scr_readw(vc, org) & 0xff00) | c, org); 373 org++; 374 if (++col == maxcol) { 375 org = screen_pos(vc, p, viewed); 376 col = 0; 377 p += maxcol; 378 } 379 } 380 } else { 381 if (p < HEADER_SIZE) { 382 char header[HEADER_SIZE]; 383 384 getconsxy(vc, header + 2); 385 while (p < HEADER_SIZE && this_round > 0) { 386 this_round--; 387 header[p++] = *con_buf0++; 388 } 389 if (!viewed) 390 putconsxy(vc, header + 2); 391 } 392 p -= HEADER_SIZE; 393 col = (p/2) % maxcol; 394 if (this_round > 0) { 395 org0 = org = screen_pos(vc, p/2, viewed); 396 if ((p & 1) && this_round > 0) { 397 char c; 398 399 this_round--; 400 c = *con_buf0++; 401#ifdef __BIG_ENDIAN 402 vcs_scr_writew(vc, c | 403 (vcs_scr_readw(vc, org) & 0xff00), org); 404#else 405 vcs_scr_writew(vc, (c << 8) | 406 (vcs_scr_readw(vc, org) & 0xff), org); 407#endif 408 org++; 409 p++; 410 if (++col == maxcol) { 411 org = screen_pos(vc, p/2, viewed); 412 col = 0; 413 } 414 } 415 p /= 2; 416 p += maxcol - col; 417 } 418 while (this_round > 1) { 419 unsigned short w; 420 421 w = get_unaligned(((unsigned short *)con_buf0)); 422 vcs_scr_writew(vc, w, org++); 423 con_buf0 += 2; 424 this_round -= 2; 425 if (++col == maxcol) { 426 org = screen_pos(vc, p, viewed); 427 col = 0; 428 p += maxcol; 429 } 430 } 431 if (this_round > 0) { 432 unsigned char c; 433 434 c = *con_buf0++; 435#ifdef __BIG_ENDIAN 436 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) | (c << 8), org); 437#else 438 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) | c, org); 439#endif 440 } 441 } 442 count -= orig_count; 443 written += orig_count; 444 buf += orig_count; 445 pos += orig_count; 446 if (org0) 447 update_region(vc, (unsigned long)(org0), org - org0); 448 } 449 *ppos += written; 450 ret = written; 451 452unlock_out: 453 release_console_sem(); 454 455 mutex_unlock(&con_buf_mtx); 456 457 return ret; 458} 459 460static int 461vcs_open(struct inode *inode, struct file *filp) 462{ 463 unsigned int currcons = iminor(inode) & 127; 464 int ret = 0; 465 466 tty_lock(); 467 if(currcons && !vc_cons_allocated(currcons-1)) 468 ret = -ENXIO; 469 tty_unlock(); 470 return ret; 471} 472 473static const struct file_operations vcs_fops = { 474 .llseek = vcs_lseek, 475 .read = vcs_read, 476 .write = vcs_write, 477 .open = vcs_open, 478}; 479 480static struct class *vc_class; 481 482void vcs_make_sysfs(int index) 483{ 484 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 1), NULL, 485 "vcs%u", index + 1); 486 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, index + 129), NULL, 487 "vcsa%u", index + 1); 488} 489 490void vcs_remove_sysfs(int index) 491{ 492 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 1)); 493 device_destroy(vc_class, MKDEV(VCS_MAJOR, index + 129)); 494} 495 496int __init vcs_init(void) 497{ 498 unsigned int i; 499 500 if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops)) 501 panic("unable to get major %d for vcs device", VCS_MAJOR); 502 vc_class = class_create(THIS_MODULE, "vc"); 503 504 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), NULL, "vcs"); 505 device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), NULL, "vcsa"); 506 for (i = 0; i < MIN_NR_CONSOLES; i++) 507 vcs_make_sysfs(i); 508 return 0; 509} 510