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1 | /* | |
2 | * consoles.c Routines to detect the system consoles | |
3 | * | |
4 | * Copyright (c) 2011 SuSE LINUX Products GmbH, All rights reserved. | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify | |
7 | * it under the terms of the GNU General Public License as published by | |
8 | * the Free Software Foundation; either version 2, or (at your option) | |
9 | * any later version. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | * | |
16 | * You should have received a copy of the GNU General Public License | |
17 | * along with this program (see the file COPYING); if not, write to the | |
18 | * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, | |
19 | * MA 02110-1301, USA. | |
20 | * | |
21 | * Author: Werner Fink <werner@suse.de> | |
22 | */ | |
23 | ||
24 | #include <limits.h> | |
25 | #include <stdio.h> | |
26 | #include <stdlib.h> | |
27 | #include <string.h> | |
28 | #include <sys/types.h> | |
29 | #include <sys/stat.h> | |
30 | #include <sys/ioctl.h> | |
31 | #include <sys/ttydefaults.h> | |
32 | #ifdef __linux__ | |
33 | # include <sys/vt.h> | |
34 | # include <sys/kd.h> | |
35 | # include <linux/serial.h> | |
36 | #endif | |
37 | #include <fcntl.h> | |
38 | #include <dirent.h> | |
39 | #include <unistd.h> | |
40 | #include "consoles.h" | |
41 | ||
42 | #ifdef __linux__ | |
43 | # include <linux/major.h> | |
44 | #endif | |
45 | ||
46 | #if !defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L) | |
47 | # ifndef typeof | |
48 | # define typeof __typeof__ | |
49 | # endif | |
50 | # ifndef restrict | |
51 | # define restrict __restrict__ | |
52 | # endif | |
53 | #endif | |
54 | ||
55 | #define alignof(type) ((sizeof(type)+(sizeof(void*)-1)) & ~(sizeof(void*)-1)) | |
56 | ||
57 | struct console *consoles; | |
58 | ||
59 | /* | |
60 | * Read and allocate one line from file, | |
61 | * the caller has to free the result | |
62 | */ | |
63 | static | |
64 | #ifdef __GNUC__ | |
65 | __attribute__((__nonnull__)) | |
66 | #endif | |
67 | char *oneline(const char *file) | |
68 | { | |
69 | FILE *fp; | |
70 | char *ret = (char*)0, *nl; | |
71 | size_t len = 0; | |
72 | ||
73 | if ((fp = fopen(file, "re")) == (FILE*)0) | |
74 | goto err; | |
75 | if (getline(&ret, &len, fp) < 0) | |
76 | goto out; | |
77 | if (len) | |
78 | ret[len-1] = '\0'; | |
79 | if ((nl = strchr(ret, '\n'))) | |
80 | *nl = '\0'; | |
81 | out: | |
82 | fclose(fp); | |
83 | err: | |
84 | return ret; | |
85 | } | |
86 | ||
87 | #ifdef __linux__ | |
88 | /* | |
89 | * Read and determine active attribute for tty below | |
90 | * /sys/class/tty, the caller has to free the result. | |
91 | */ | |
92 | static | |
93 | __attribute__((__malloc__)) | |
94 | char *actattr(const char *tty) | |
95 | { | |
96 | char *ret = (char*)0; | |
97 | char *path; | |
98 | ||
99 | if (!tty || *tty == '\0') | |
100 | goto err; | |
101 | ||
102 | if (asprintf(&path, "/sys/class/tty/%s/active", tty) < 0) | |
103 | goto err; | |
104 | ||
105 | if ((ret = oneline(path)) == (char*)0) | |
106 | goto out; | |
107 | out: | |
108 | free(path); | |
109 | err: | |
110 | return ret; | |
111 | } | |
112 | ||
113 | /* | |
114 | * Read and determine device attribute for tty below | |
115 | * /sys/class/tty. | |
116 | */ | |
117 | static | |
118 | dev_t devattr(const char *tty) | |
119 | { | |
120 | unsigned int maj, min; | |
121 | dev_t dev = 0; | |
122 | char *path, *value; | |
123 | ||
124 | if (!tty || *tty == '\0') | |
125 | goto err; | |
126 | ||
127 | if (asprintf(&path, "/sys/class/tty/%s/dev", tty) < 0) | |
128 | goto err; | |
129 | ||
130 | if ((value = oneline(path)) == (char*)0) | |
131 | goto out; | |
132 | ||
133 | if (sscanf(value, "%u:%u", &maj, &min) == 2) | |
134 | dev = makedev(maj, min); | |
135 | free(value); | |
136 | out: | |
137 | free(path); | |
138 | err: | |
139 | return dev; | |
140 | } | |
141 | #endif /* __linux__ */ | |
142 | ||
143 | /* | |
144 | * Search below /dev for the characer device in | |
145 | * the local `dev_t comparedev' variable. | |
146 | */ | |
147 | static dev_t comparedev; | |
148 | static | |
149 | #ifdef __GNUC__ | |
150 | __attribute__((__nonnull__,__malloc__,__hot__)) | |
151 | #endif | |
152 | char* scandev(DIR *dir) | |
153 | { | |
154 | char *name = (char*)0; | |
155 | struct dirent *dent; | |
156 | int fd; | |
157 | ||
158 | fd = dirfd(dir); | |
159 | rewinddir(dir); | |
160 | while ((dent = readdir(dir))) { | |
161 | char path[PATH_MAX]; | |
162 | struct stat st; | |
163 | if (fstatat(fd, dent->d_name, &st, 0) < 0) | |
164 | continue; | |
165 | if (!S_ISCHR(st.st_mode)) | |
166 | continue; | |
167 | if (comparedev != st.st_rdev) | |
168 | continue; | |
169 | if ((size_t)snprintf(path, sizeof(path), "/dev/%s", dent->d_name) >= sizeof(path)) | |
170 | continue; | |
171 | name = realpath(path, NULL); | |
172 | break; | |
173 | } | |
174 | return name; | |
175 | } | |
176 | ||
177 | /* | |
178 | * Default control characters for an unknown terminal line. | |
179 | */ | |
180 | static | |
181 | struct chardata initcp = { | |
182 | CERASE, | |
183 | CKILL, | |
184 | CTRL('r'), | |
185 | 0 | |
186 | }; | |
187 | ||
188 | /* | |
189 | * Allocate an aligned `struct console' memory area, | |
190 | * initialize its default values, and append it to | |
191 | * the global linked list. | |
192 | */ | |
193 | ||
194 | static int concount; /* Counter for console IDs */ | |
195 | ||
196 | static | |
197 | #ifdef __GNUC__ | |
198 | __attribute__((__nonnull__,__hot__)) | |
199 | #endif | |
200 | void consalloc(char * name) | |
201 | { | |
202 | struct console *restrict tail; | |
203 | ||
204 | if (posix_memalign((void*)&tail, sizeof(void*), alignof(typeof(struct console))) != 0) | |
205 | perror("memory allocation"); | |
206 | ||
207 | tail->next = (struct console*)0; | |
208 | tail->tty = name; | |
209 | ||
210 | tail->file = (FILE*)0; | |
211 | tail->flags = 0; | |
212 | tail->fd = -1; | |
213 | tail->id = concount++; | |
214 | tail->pid = 0; | |
215 | memset(&tail->tio, 0, sizeof(tail->tio)); | |
216 | memcpy(&tail->cp, &initcp, sizeof(struct chardata)); | |
217 | ||
218 | if (!consoles) | |
219 | consoles = tail; | |
220 | else | |
221 | consoles->next = tail; | |
222 | } | |
223 | ||
224 | /* | |
225 | * Try to detect the real device(s) used for the system console | |
226 | * /dev/console if but only if /dev/console is used. On Linux | |
227 | * this can be more than one device, e.g. a serial line as well | |
228 | * as a virtual console as well as a simple printer. | |
229 | * | |
230 | * Returns 1 if stdout and stderr should be reconnected and 0 | |
231 | * otherwise. | |
232 | */ | |
233 | int detect_consoles(const char *device, int fallback) | |
234 | { | |
235 | int fd, ret = 0; | |
236 | #ifdef __linux__ | |
237 | char *attrib, *cmdline; | |
238 | FILE *fc; | |
239 | #endif | |
240 | if (!device || *device == '\0') | |
241 | fd = dup(fallback); | |
242 | else { | |
243 | fd = open(device, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC); | |
244 | ret = 1; | |
245 | } | |
246 | ||
247 | if (fd >= 0) { | |
248 | DIR *dir; | |
249 | char *name; | |
250 | struct stat st; | |
251 | #ifdef TIOCGDEV | |
252 | unsigned int devnum; | |
253 | #endif | |
254 | ||
255 | if (fstat(fd, &st) < 0) { | |
256 | close(fd); | |
257 | goto fallback; | |
258 | } | |
259 | comparedev = st.st_rdev; | |
260 | ||
261 | if (ret && (fstat(fallback, &st) < 0 || comparedev != st.st_rdev)) | |
262 | dup2(fd, fallback); | |
263 | #ifdef __linux__ | |
264 | /* | |
265 | * Check if the device detection for Linux system console should be used. | |
266 | */ | |
267 | if (comparedev == makedev(TTYAUX_MAJOR, 0)) { /* /dev/tty */ | |
268 | close(fd); | |
269 | device = "/dev/tty"; | |
270 | goto fallback; | |
271 | } | |
272 | if (comparedev == makedev(TTYAUX_MAJOR, 1)) { /* /dev/console */ | |
273 | close(fd); | |
274 | goto console; | |
275 | } | |
276 | if (comparedev == makedev(TTYAUX_MAJOR, 2)) { /* /dev/ptmx */ | |
277 | close(fd); | |
278 | device = "/dev/tty"; | |
279 | goto fallback; | |
280 | } | |
281 | if (comparedev == makedev(TTY_MAJOR, 0)) { /* /dev/tty0 */ | |
282 | struct vt_stat vt; | |
283 | if (ioctl(fd, VT_GETSTATE, &vt) < 0) { | |
284 | close(fd); | |
285 | goto fallback; | |
286 | } | |
287 | comparedev = makedev(TTY_MAJOR, (int)vt.v_active); | |
288 | } | |
289 | #endif | |
290 | #ifdef TIOCGDEV | |
291 | if (ioctl (fd, TIOCGDEV, &devnum) < 0) { | |
292 | close(fd); | |
293 | goto fallback; | |
294 | } | |
295 | comparedev = (dev_t)devnum; | |
296 | #endif | |
297 | close(fd); | |
298 | dir = opendir("/dev"); | |
299 | if (!dir) | |
300 | goto fallback; | |
301 | name = scandev(dir); | |
302 | if (name) | |
303 | consalloc(name); | |
304 | closedir(dir); | |
305 | if (!consoles) | |
306 | goto fallback; | |
307 | return ret; | |
308 | } | |
309 | #ifdef __linux__ | |
310 | console: | |
311 | /* | |
312 | * Detection of devices used for Linux system consolei using | |
313 | * the /proc/consoles API with kernel 2.6.38 and higher. | |
314 | */ | |
315 | if ((fc = fopen("/proc/consoles", "re"))) { | |
316 | char fbuf[16]; | |
317 | int maj, min; | |
318 | DIR *dir; | |
319 | dir = opendir("/dev"); | |
320 | if (!dir) { | |
321 | fclose(fc); | |
322 | goto fallback; | |
323 | } | |
324 | while ((fscanf(fc, "%*s %*s (%[^)]) %d:%d", &fbuf[0], &maj, &min) == 3)) { | |
325 | char * name; | |
326 | ||
327 | if (!strchr(fbuf, 'E')) | |
328 | continue; | |
329 | comparedev = makedev(maj, min); | |
330 | ||
331 | name = scandev(dir); | |
332 | if (!name) | |
333 | continue; | |
334 | consalloc(name); | |
335 | } | |
336 | closedir(dir); | |
337 | fclose(fc); | |
338 | return ret; | |
339 | } | |
340 | /* | |
341 | * Detection of devices used for Linux system console using | |
342 | * the sysfs /sys/class/tty/ API with kernel 2.6.37 and higher. | |
343 | */ | |
344 | if ((attrib = actattr("console"))) { | |
345 | char *words = attrib, *token; | |
346 | DIR *dir; | |
347 | ||
348 | dir = opendir("/dev"); | |
349 | if (!dir) { | |
350 | free(attrib); | |
351 | goto fallback; | |
352 | } | |
353 | while ((token = strsep(&words, " \t\r\n"))) { | |
354 | char * name; | |
355 | ||
356 | if (*token == '\0') | |
357 | continue; | |
358 | comparedev = devattr(token); | |
359 | if (comparedev == makedev(TTY_MAJOR, 0)) { | |
360 | char *tmp = actattr(token); | |
361 | if (!tmp) | |
362 | continue; | |
363 | comparedev = devattr(tmp); | |
364 | free(tmp); | |
365 | } | |
366 | ||
367 | name = scandev(dir); | |
368 | if (!name) | |
369 | continue; | |
370 | consalloc(name); | |
371 | } | |
372 | closedir(dir); | |
373 | free(attrib); | |
374 | if (!consoles) | |
375 | goto fallback; | |
376 | return ret; | |
377 | ||
378 | } | |
379 | /* | |
380 | * Detection of devices used for Linux system console using | |
381 | * kernel parameter on the kernels command line. | |
382 | */ | |
383 | if ((cmdline = oneline("/proc/cmdline"))) { | |
384 | char *words= cmdline, *token; | |
385 | DIR *dir; | |
386 | ||
387 | dir = opendir("/dev"); | |
388 | if (!dir) { | |
389 | free(cmdline); | |
390 | goto fallback; | |
391 | } | |
392 | while ((token = strsep(&words, " \t\r\n"))) { | |
393 | #ifdef TIOCGDEV | |
394 | unsigned int devnum; | |
395 | #else | |
396 | struct vt_stat vt; | |
397 | struct stat st; | |
398 | #endif | |
399 | char *colon, *name; | |
400 | ||
401 | if (*token != 'c') | |
402 | continue; | |
403 | ||
404 | if (strncmp(token, "console=", 8) != 0) | |
405 | continue; | |
406 | token += 8; | |
407 | ||
408 | if (strcmp(token, "brl") == 0) | |
409 | token += 4; | |
410 | if ((colon = strchr(token, ','))) | |
411 | *colon = '\0'; | |
412 | ||
413 | if (asprintf(&name, "/dev/%s", token) < 0) | |
414 | continue; | |
415 | ||
416 | if ((fd = open(name, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC)) < 0) { | |
417 | free(name); | |
418 | continue; | |
419 | } | |
420 | free(name); | |
421 | #ifdef TIOCGDEV | |
422 | if (ioctl (fd, TIOCGDEV, &devnum) < 0) { | |
423 | close(fd); | |
424 | continue; | |
425 | } | |
426 | comparedev = (dev_t)devnum; | |
427 | #else | |
428 | if (fstat(fd, &st) < 0) { | |
429 | close(fd); | |
430 | continue; | |
431 | } | |
432 | comparedev = st.st_rdev; | |
433 | if (comparedev == makedev(TTY_MAJOR, 0)) { | |
434 | if (ioctl(fd, VT_GETSTATE, &vt) < 0) { | |
435 | close(fd); | |
436 | continue; | |
437 | } | |
438 | comparedev = makedev(TTY_MAJOR, (int)vt.v_active); | |
439 | } | |
440 | #endif | |
441 | close(fd); | |
442 | ||
443 | name = scandev(dir); | |
444 | if (!name) | |
445 | continue; | |
446 | consalloc(name); | |
447 | } | |
448 | closedir(dir); | |
449 | free(cmdline); | |
450 | /* | |
451 | * Detection of the device used for Linux system console using | |
452 | * the ioctl TIOCGDEV if available (e.g. official 2.6.38). | |
453 | */ | |
454 | if (!consoles) { | |
455 | #ifdef TIOCGDEV | |
456 | unsigned int devnum; | |
457 | const char *name; | |
458 | ||
459 | if (!device || *device == '\0') | |
460 | fd = dup(fallback); | |
461 | else fd = open(device, O_RDWR|O_NONBLOCK|O_NOCTTY|O_CLOEXEC); | |
462 | ||
463 | if (fd < 0) | |
464 | goto fallback; | |
465 | ||
466 | if (ioctl (fd, TIOCGDEV, &devnum) < 0) { | |
467 | close(fd); | |
468 | goto fallback; | |
469 | } | |
470 | comparedev = (dev_t)devnum; | |
471 | close(fd); | |
472 | ||
473 | if (device && *device != '\0') | |
474 | name = device; | |
475 | else name = ttyname(fallback); | |
476 | ||
477 | if (!name) | |
478 | name = "/dev/tty1"; | |
479 | ||
480 | consalloc(strdup(name)); | |
481 | if (consoles) { | |
482 | if (!device || *device == '\0') | |
483 | consoles->fd = fallback; | |
484 | return ret; | |
485 | } | |
486 | #endif | |
487 | goto fallback; | |
488 | } | |
489 | return ret; | |
490 | } | |
491 | #endif /* __linux __ */ | |
492 | fallback: | |
493 | if (fallback >= 0) { | |
494 | const char *name; | |
495 | ||
496 | if (device && *device != '\0') | |
497 | name = device; | |
498 | else name = ttyname(fallback); | |
499 | ||
500 | if (!name) | |
501 | name = "/dev/tty"; | |
502 | ||
503 | consalloc(strdup(name)); | |
504 | if (consoles) | |
505 | consoles->fd = fallback; | |
506 | } | |
507 | return ret; | |
508 | } |