tty: simplify calling of put_pid.
[linux-2.6] / drivers / char / vc_screen.c
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/vt_kern.h>
32 #include <linux/selection.h>
33 #include <linux/kbd_kern.h>
34 #include <linux/console.h>
35 #include <linux/smp_lock.h>
36 #include <linux/device.h>
37 #include <asm/uaccess.h>
38 #include <asm/byteorder.h>
39 #include <asm/unaligned.h>
40
41 #undef attr
42 #undef org
43 #undef addr
44 #define HEADER_SIZE     4
45
46 static int
47 vcs_size(struct inode *inode)
48 {
49         int size;
50         int minor = iminor(inode);
51         int currcons = minor & 127;
52         struct vc_data *vc;
53
54         if (currcons == 0)
55                 currcons = fg_console;
56         else
57                 currcons--;
58         if (!vc_cons_allocated(currcons))
59                 return -ENXIO;
60         vc = vc_cons[currcons].d;
61
62         size = vc->vc_rows * vc->vc_cols;
63
64         if (minor & 128)
65                 size = 2*size + HEADER_SIZE;
66         return size;
67 }
68
69 static loff_t vcs_lseek(struct file *file, loff_t offset, int orig)
70 {
71         int size;
72
73         down(&con_buf_sem);
74         size = vcs_size(file->f_path.dentry->d_inode);
75         switch (orig) {
76                 default:
77                         up(&con_buf_sem);
78                         return -EINVAL;
79                 case 2:
80                         offset += size;
81                         break;
82                 case 1:
83                         offset += file->f_pos;
84                 case 0:
85                         break;
86         }
87         if (offset < 0 || offset > size) {
88                 up(&con_buf_sem);
89                 return -EINVAL;
90         }
91         file->f_pos = offset;
92         up(&con_buf_sem);
93         return file->f_pos;
94 }
95
96
97 static ssize_t
98 vcs_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
99 {
100         struct inode *inode = file->f_path.dentry->d_inode;
101         unsigned int currcons = iminor(inode);
102         struct vc_data *vc;
103         long pos;
104         long viewed, attr, read;
105         int col, maxcol;
106         unsigned short *org = NULL;
107         ssize_t ret;
108
109         down(&con_buf_sem);
110
111         pos = *ppos;
112
113         /* Select the proper current console and verify
114          * sanity of the situation under the console lock.
115          */
116         acquire_console_sem();
117
118         attr = (currcons & 128);
119         currcons = (currcons & 127);
120         if (currcons == 0) {
121                 currcons = fg_console;
122                 viewed = 1;
123         } else {
124                 currcons--;
125                 viewed = 0;
126         }
127         ret = -ENXIO;
128         if (!vc_cons_allocated(currcons))
129                 goto unlock_out;
130         vc = vc_cons[currcons].d;
131
132         ret = -EINVAL;
133         if (pos < 0)
134                 goto unlock_out;
135         read = 0;
136         ret = 0;
137         while (count) {
138                 char *con_buf0, *con_buf_start;
139                 long this_round, size;
140                 ssize_t orig_count;
141                 long p = pos;
142
143                 /* Check whether we are above size each round,
144                  * as copy_to_user at the end of this loop
145                  * could sleep.
146                  */
147                 size = vcs_size(inode);
148                 if (pos >= size)
149                         break;
150                 if (count > size - pos)
151                         count = size - pos;
152
153                 this_round = count;
154                 if (this_round > CON_BUF_SIZE)
155                         this_round = CON_BUF_SIZE;
156
157                 /* Perform the whole read into the local con_buf.
158                  * Then we can drop the console spinlock and safely
159                  * attempt to move it to userspace.
160                  */
161
162                 con_buf_start = con_buf0 = con_buf;
163                 orig_count = this_round;
164                 maxcol = vc->vc_cols;
165                 if (!attr) {
166                         org = screen_pos(vc, p, viewed);
167                         col = p % maxcol;
168                         p += maxcol - col;
169                         while (this_round-- > 0) {
170                                 *con_buf0++ = (vcs_scr_readw(vc, org++) & 0xff);
171                                 if (++col == maxcol) {
172                                         org = screen_pos(vc, p, viewed);
173                                         col = 0;
174                                         p += maxcol;
175                                 }
176                         }
177                 } else {
178                         if (p < HEADER_SIZE) {
179                                 size_t tmp_count;
180
181                                 con_buf0[0] = (char)vc->vc_rows;
182                                 con_buf0[1] = (char)vc->vc_cols;
183                                 getconsxy(vc, con_buf0 + 2);
184
185                                 con_buf_start += p;
186                                 this_round += p;
187                                 if (this_round > CON_BUF_SIZE) {
188                                         this_round = CON_BUF_SIZE;
189                                         orig_count = this_round - p;
190                                 }
191
192                                 tmp_count = HEADER_SIZE;
193                                 if (tmp_count > this_round)
194                                         tmp_count = this_round;
195
196                                 /* Advance state pointers and move on. */
197                                 this_round -= tmp_count;
198                                 p = HEADER_SIZE;
199                                 con_buf0 = con_buf + HEADER_SIZE;
200                                 /* If this_round >= 0, then p is even... */
201                         } else if (p & 1) {
202                                 /* Skip first byte for output if start address is odd
203                                  * Update region sizes up/down depending on free
204                                  * space in buffer.
205                                  */
206                                 con_buf_start++;
207                                 if (this_round < CON_BUF_SIZE)
208                                         this_round++;
209                                 else
210                                         orig_count--;
211                         }
212                         if (this_round > 0) {
213                                 unsigned short *tmp_buf = (unsigned short *)con_buf0;
214
215                                 p -= HEADER_SIZE;
216                                 p /= 2;
217                                 col = p % maxcol;
218
219                                 org = screen_pos(vc, p, viewed);
220                                 p += maxcol - col;
221
222                                 /* Buffer has even length, so we can always copy
223                                  * character + attribute. We do not copy last byte
224                                  * to userspace if this_round is odd.
225                                  */
226                                 this_round = (this_round + 1) >> 1;
227
228                                 while (this_round) {
229                                         *tmp_buf++ = vcs_scr_readw(vc, org++);
230                                         this_round --;
231                                         if (++col == maxcol) {
232                                                 org = screen_pos(vc, p, viewed);
233                                                 col = 0;
234                                                 p += maxcol;
235                                         }
236                                 }
237                         }
238                 }
239
240                 /* Finally, release the console semaphore while we push
241                  * all the data to userspace from our temporary buffer.
242                  *
243                  * AKPM: Even though it's a semaphore, we should drop it because
244                  * the pagefault handling code may want to call printk().
245                  */
246
247                 release_console_sem();
248                 ret = copy_to_user(buf, con_buf_start, orig_count);
249                 acquire_console_sem();
250
251                 if (ret) {
252                         read += (orig_count - ret);
253                         ret = -EFAULT;
254                         break;
255                 }
256                 buf += orig_count;
257                 pos += orig_count;
258                 read += orig_count;
259                 count -= orig_count;
260         }
261         *ppos += read;
262         if (read)
263                 ret = read;
264 unlock_out:
265         release_console_sem();
266         up(&con_buf_sem);
267         return ret;
268 }
269
270 static ssize_t
271 vcs_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
272 {
273         struct inode *inode = file->f_path.dentry->d_inode;
274         unsigned int currcons = iminor(inode);
275         struct vc_data *vc;
276         long pos;
277         long viewed, attr, size, written;
278         char *con_buf0;
279         int col, maxcol;
280         u16 *org0 = NULL, *org = NULL;
281         size_t ret;
282
283         down(&con_buf_sem);
284
285         pos = *ppos;
286
287         /* Select the proper current console and verify
288          * sanity of the situation under the console lock.
289          */
290         acquire_console_sem();
291
292         attr = (currcons & 128);
293         currcons = (currcons & 127);
294
295         if (currcons == 0) {
296                 currcons = fg_console;
297                 viewed = 1;
298         } else {
299                 currcons--;
300                 viewed = 0;
301         }
302         ret = -ENXIO;
303         if (!vc_cons_allocated(currcons))
304                 goto unlock_out;
305         vc = vc_cons[currcons].d;
306
307         size = vcs_size(inode);
308         ret = -EINVAL;
309         if (pos < 0 || pos > size)
310                 goto unlock_out;
311         if (count > size - pos)
312                 count = size - pos;
313         written = 0;
314         while (count) {
315                 long this_round = count;
316                 size_t orig_count;
317                 long p;
318
319                 if (this_round > CON_BUF_SIZE)
320                         this_round = CON_BUF_SIZE;
321
322                 /* Temporarily drop the console lock so that we can read
323                  * in the write data from userspace safely.
324                  */
325                 release_console_sem();
326                 ret = copy_from_user(con_buf, buf, this_round);
327                 acquire_console_sem();
328
329                 if (ret) {
330                         this_round -= ret;
331                         if (!this_round) {
332                                 /* Abort loop if no data were copied. Otherwise
333                                  * fail with -EFAULT.
334                                  */
335                                 if (written)
336                                         break;
337                                 ret = -EFAULT;
338                                 goto unlock_out;
339                         }
340                 }
341
342                 /* The vcs_size might have changed while we slept to grab
343                  * the user buffer, so recheck.
344                  * Return data written up to now on failure.
345                  */
346                 size = vcs_size(inode);
347                 if (pos >= size)
348                         break;
349                 if (this_round > size - pos)
350                         this_round = size - pos;
351
352                 /* OK, now actually push the write to the console
353                  * under the lock using the local kernel buffer.
354                  */
355
356                 con_buf0 = con_buf;
357                 orig_count = this_round;
358                 maxcol = vc->vc_cols;
359                 p = pos;
360                 if (!attr) {
361                         org0 = org = screen_pos(vc, p, viewed);
362                         col = p % maxcol;
363                         p += maxcol - col;
364
365                         while (this_round > 0) {
366                                 unsigned char c = *con_buf0++;
367
368                                 this_round--;
369                                 vcs_scr_writew(vc,
370                                                (vcs_scr_readw(vc, org) & 0xff00) | c, org);
371                                 org++;
372                                 if (++col == maxcol) {
373                                         org = screen_pos(vc, p, viewed);
374                                         col = 0;
375                                         p += maxcol;
376                                 }
377                         }
378                 } else {
379                         if (p < HEADER_SIZE) {
380                                 char header[HEADER_SIZE];
381
382                                 getconsxy(vc, header + 2);
383                                 while (p < HEADER_SIZE && this_round > 0) {
384                                         this_round--;
385                                         header[p++] = *con_buf0++;
386                                 }
387                                 if (!viewed)
388                                         putconsxy(vc, header + 2);
389                         }
390                         p -= HEADER_SIZE;
391                         col = (p/2) % maxcol;
392                         if (this_round > 0) {
393                                 org0 = org = screen_pos(vc, p/2, viewed);
394                                 if ((p & 1) && this_round > 0) {
395                                         char c;
396
397                                         this_round--;
398                                         c = *con_buf0++;
399 #ifdef __BIG_ENDIAN
400                                         vcs_scr_writew(vc, c |
401                                              (vcs_scr_readw(vc, org) & 0xff00), org);
402 #else
403                                         vcs_scr_writew(vc, (c << 8) |
404                                              (vcs_scr_readw(vc, org) & 0xff), org);
405 #endif
406                                         org++;
407                                         p++;
408                                         if (++col == maxcol) {
409                                                 org = screen_pos(vc, p/2, viewed);
410                                                 col = 0;
411                                         }
412                                 }
413                                 p /= 2;
414                                 p += maxcol - col;
415                         }
416                         while (this_round > 1) {
417                                 unsigned short w;
418
419                                 w = get_unaligned(((unsigned short *)con_buf0));
420                                 vcs_scr_writew(vc, w, org++);
421                                 con_buf0 += 2;
422                                 this_round -= 2;
423                                 if (++col == maxcol) {
424                                         org = screen_pos(vc, p, viewed);
425                                         col = 0;
426                                         p += maxcol;
427                                 }
428                         }
429                         if (this_round > 0) {
430                                 unsigned char c;
431
432                                 c = *con_buf0++;
433 #ifdef __BIG_ENDIAN
434                                 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff) | (c << 8), org);
435 #else
436                                 vcs_scr_writew(vc, (vcs_scr_readw(vc, org) & 0xff00) | c, org);
437 #endif
438                         }
439                 }
440                 count -= orig_count;
441                 written += orig_count;
442                 buf += orig_count;
443                 pos += orig_count;
444                 if (org0)
445                         update_region(vc, (unsigned long)(org0), org - org0);
446         }
447         *ppos += written;
448         ret = written;
449
450 unlock_out:
451         release_console_sem();
452
453         up(&con_buf_sem);
454
455         return ret;
456 }
457
458 static int
459 vcs_open(struct inode *inode, struct file *filp)
460 {
461         unsigned int currcons = iminor(inode) & 127;
462         if(currcons && !vc_cons_allocated(currcons-1))
463                 return -ENXIO;
464         return 0;
465 }
466
467 static const struct file_operations vcs_fops = {
468         .llseek         = vcs_lseek,
469         .read           = vcs_read,
470         .write          = vcs_write,
471         .open           = vcs_open,
472 };
473
474 static struct class *vc_class;
475
476 void vcs_make_sysfs(struct tty_struct *tty)
477 {
478         device_create(vc_class, NULL, MKDEV(VCS_MAJOR, tty->index + 1),
479                         "vcs%u", tty->index + 1);
480         device_create(vc_class, NULL, MKDEV(VCS_MAJOR, tty->index + 129),
481                         "vcsa%u", tty->index + 1);
482 }
483
484 void vcs_remove_sysfs(struct tty_struct *tty)
485 {
486         device_destroy(vc_class, MKDEV(VCS_MAJOR, tty->index + 1));
487         device_destroy(vc_class, MKDEV(VCS_MAJOR, tty->index + 129));
488 }
489
490 int __init vcs_init(void)
491 {
492         if (register_chrdev(VCS_MAJOR, "vcs", &vcs_fops))
493                 panic("unable to get major %d for vcs device", VCS_MAJOR);
494         vc_class = class_create(THIS_MODULE, "vc");
495
496         device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 0), "vcs");
497         device_create(vc_class, NULL, MKDEV(VCS_MAJOR, 128), "vcsa");
498         return 0;
499 }