FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_hints.c
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2000,2001 Peter Wemm <peter@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD: releng/12.0/sys/kern/subr_hints.c 338020 2018-08-18 19:45:56Z kevans $");
31
32 #include <sys/param.h>
33 #include <sys/lock.h>
34 #include <sys/kernel.h>
35 #include <sys/malloc.h>
36 #include <sys/mutex.h>
37 #include <sys/sysctl.h>
38 #include <sys/systm.h>
39 #include <sys/bus.h>
40
41 #define FBACK_MDENV 0 /* MD env (e.g. loader.conf) */
42 #define FBACK_STENV 1 /* Static env */
43 #define FBACK_STATIC 2 /* static_hints */
44
45 /*
46 * We'll use hintenv_merged to indicate that the dynamic environment has been
47 * properly prepared for hint usage. This implies that the dynamic environment
48 * has already been setup (dynamic_kenv) and that we have added any supplied
49 * static_hints to the dynamic environment.
50 */
51 static bool hintenv_merged;
52 /* Static environment and static hints cannot change, so we'll skip known bad */
53 static bool stenv_skip;
54 static bool sthints_skip;
55 /*
56 * Access functions for device resources.
57 */
58
59 static void
60 static_hints_to_env(void *data __unused)
61 {
62 const char *cp;
63 char *line, *eq;
64 int eqidx, i;
65
66 cp = static_hints;
67 while (cp && *cp != '\0') {
68 eq = strchr(cp, '=');
69 if (eq == NULL)
70 /* Bad hint value */
71 continue;
72 eqidx = eq - cp;
73
74 i = strlen(cp);
75 line = malloc(i + 1, M_TEMP, M_WAITOK);
76 strcpy(line, cp);
77 line[eqidx] = line[i] = '\0';
78 /*
79 * Before adding a hint to the dynamic environment, check if
80 * another value for said hint has already been added. This is
81 * needed because static environment overrides static hints and
82 * dynamic environment overrides all.
83 */
84 if (testenv(line) == 0)
85 kern_setenv(line, line + eqidx + 1);
86 free(line, M_TEMP);
87 cp += i + 1;
88 }
89 hintenv_merged = true;
90 }
91
92 /* Any time after dynamic env is setup */
93 SYSINIT(hintenv, SI_SUB_KMEM + 1, SI_ORDER_SECOND, static_hints_to_env, NULL);
94
95 /*
96 * Checks the environment to see if we even have any hints. If it has no hints,
97 * then res_find can take the hint that there's no point in searching it and
98 * either move on to the next environment or fail early.
99 */
100 static bool
101 _res_checkenv(char *envp)
102 {
103 char *cp;
104
105 cp = envp;
106 while (cp) {
107 if (strncmp(cp, "hint.", 5) == 0)
108 return (true);
109 while (*cp != '\0')
110 cp++;
111 cp++;
112 if (*cp == '\0')
113 break;
114 }
115 return (false);
116 }
117
118 /*
119 * Evil wildcarding resource string lookup.
120 * This walks the supplied env string table and returns a match.
121 * The start point can be remembered for incremental searches.
122 */
123 static int
124 res_find(char **hintp_cookie, int *line, int *startln,
125 const char *name, int *unit, const char *resname, const char *value,
126 const char **ret_name, int *ret_namelen, int *ret_unit,
127 const char **ret_resname, int *ret_resnamelen, const char **ret_value)
128 {
129 int fbacklvl = FBACK_MDENV, i = 0, n = 0;
130 char r_name[32];
131 int r_unit;
132 char r_resname[32];
133 char r_value[128];
134 const char *s, *cp;
135 char *hintp, *p;
136 bool dyn_used = false;
137
138
139 /*
140 * We are expecting that the caller will pass us a hintp_cookie that
141 * they are tracking. Upon entry, if *hintp_cookie is *not* set, this
142 * indicates to us that we should be figuring out based on the current
143 * environment where to search. This keeps us sane throughout the
144 * entirety of a single search.
145 */
146 if (*hintp_cookie == NULL) {
147 hintp = NULL;
148 if (hintenv_merged) {
149 /*
150 * static_hints, if it was previously used, has
151 * already been folded in to the environment
152 * by this point.
153 */
154 mtx_lock(&kenv_lock);
155 cp = kenvp[0];
156 for (i = 0; cp != NULL; cp = kenvp[++i]) {
157 if (!strncmp(cp, "hint.", 5)) {
158 hintp = kenvp[0];
159 break;
160 }
161 }
162 mtx_unlock(&kenv_lock);
163 dyn_used = true;
164 } else {
165 /*
166 * We'll have a chance to keep coming back here until
167 * we've actually exhausted all of our possibilities.
168 * We might have chosen the MD/Static env because it
169 * had some kind of hints, but perhaps it didn't have
170 * the hint we are looking for. We don't provide any
171 * fallback when searching the dynamic environment.
172 */
173 fallback:
174 if (dyn_used || fbacklvl >= FBACK_STATIC)
175 return (ENOENT);
176
177 switch (fbacklvl) {
178 case FBACK_MDENV:
179 fbacklvl++;
180 if (_res_checkenv(md_envp)) {
181 hintp = md_envp;
182 break;
183 }
184
185 /* FALLTHROUGH */
186 case FBACK_STENV:
187 fbacklvl++;
188 if (!stenv_skip && _res_checkenv(kern_envp)) {
189 hintp = kern_envp;
190 break;
191 } else
192 stenv_skip = true;
193
194 /* FALLTHROUGH */
195 case FBACK_STATIC:
196 fbacklvl++;
197 /* We'll fallback to static_hints if needed/can */
198 if (!sthints_skip &&
199 _res_checkenv(static_hints))
200 hintp = static_hints;
201 else
202 sthints_skip = true;
203
204 break;
205 default:
206 return (ENOENT);
207 }
208 }
209
210 if (hintp == NULL)
211 return (ENOENT);
212 *hintp_cookie = hintp;
213 } else {
214 hintp = *hintp_cookie;
215 if (hintenv_merged && hintp == kenvp[0])
216 dyn_used = true;
217 else
218 /*
219 * If we aren't using the dynamic environment, we need
220 * to run through the proper fallback procedure again.
221 * This is so that we do continuations right if we're
222 * working with *line and *startln.
223 */
224 goto fallback;
225 }
226
227 if (dyn_used) {
228 mtx_lock(&kenv_lock);
229 i = 0;
230 }
231
232 cp = hintp;
233 while (cp) {
234 (*line)++;
235 if (strncmp(cp, "hint.", 5) != 0)
236 goto nexthint;
237 n = sscanf(cp, "hint.%32[^.].%d.%32[^=]=%127s", r_name, &r_unit,
238 r_resname, r_value);
239 if (n != 4) {
240 printf("CONFIG: invalid hint '%s'\n", cp);
241 p = strchr(cp, 'h');
242 *p = 'H';
243 goto nexthint;
244 }
245 if (startln && *startln >= 0 && *line < *startln)
246 goto nexthint;
247 if (name && strcmp(name, r_name) != 0)
248 goto nexthint;
249 if (unit && *unit != r_unit)
250 goto nexthint;
251 if (resname && strcmp(resname, r_resname) != 0)
252 goto nexthint;
253 if (value && strcmp(value, r_value) != 0)
254 goto nexthint;
255 /* Successfully found a hint matching all criteria */
256 break;
257 nexthint:
258 if (dyn_used) {
259 cp = kenvp[++i];
260 if (cp == NULL)
261 break;
262 } else {
263 while (*cp != '\0')
264 cp++;
265 cp++;
266 if (*cp == '\0') {
267 cp = NULL;
268 break;
269 }
270 }
271 }
272 if (dyn_used)
273 mtx_unlock(&kenv_lock);
274 if (cp == NULL)
275 goto fallback;
276
277 s = cp;
278 /* This is a bit of a hack, but at least is reentrant */
279 /* Note that it returns some !unterminated! strings. */
280 s = strchr(s, '.') + 1; /* start of device */
281 if (ret_name)
282 *ret_name = s;
283 s = strchr(s, '.') + 1; /* start of unit */
284 if (ret_namelen && ret_name)
285 *ret_namelen = s - *ret_name - 1; /* device length */
286 if (ret_unit)
287 *ret_unit = r_unit;
288 s = strchr(s, '.') + 1; /* start of resname */
289 if (ret_resname)
290 *ret_resname = s;
291 s = strchr(s, '=') + 1; /* start of value */
292 if (ret_resnamelen && ret_resname)
293 *ret_resnamelen = s - *ret_resname - 1; /* value len */
294 if (ret_value)
295 *ret_value = s;
296 if (startln) /* line number for anchor */
297 *startln = *line + 1;
298 return 0;
299 }
300
301 /*
302 * Search all the data sources for matches to our query. We look for
303 * dynamic hints first as overrides for static or fallback hints.
304 */
305 static int
306 resource_find(int *line, int *startln,
307 const char *name, int *unit, const char *resname, const char *value,
308 const char **ret_name, int *ret_namelen, int *ret_unit,
309 const char **ret_resname, int *ret_resnamelen, const char **ret_value)
310 {
311 int i;
312 int un;
313 char *hintp;
314
315 *line = 0;
316 hintp = NULL;
317
318 /* Search for exact unit matches first */
319 i = res_find(&hintp, line, startln, name, unit, resname, value,
320 ret_name, ret_namelen, ret_unit, ret_resname, ret_resnamelen,
321 ret_value);
322 if (i == 0)
323 return 0;
324 if (unit == NULL)
325 return ENOENT;
326 /* If we are still here, search for wildcard matches */
327 un = -1;
328 i = res_find(&hintp, line, startln, name, &un, resname, value,
329 ret_name, ret_namelen, ret_unit, ret_resname, ret_resnamelen,
330 ret_value);
331 if (i == 0)
332 return 0;
333 return ENOENT;
334 }
335
336 int
337 resource_int_value(const char *name, int unit, const char *resname, int *result)
338 {
339 int error;
340 const char *str;
341 char *op;
342 unsigned long val;
343 int line;
344
345 line = 0;
346 error = resource_find(&line, NULL, name, &unit, resname, NULL,
347 NULL, NULL, NULL, NULL, NULL, &str);
348 if (error)
349 return error;
350 if (*str == '\0')
351 return EFTYPE;
352 val = strtoul(str, &op, 0);
353 if (*op != '\0')
354 return EFTYPE;
355 *result = val;
356 return 0;
357 }
358
359 int
360 resource_long_value(const char *name, int unit, const char *resname,
361 long *result)
362 {
363 int error;
364 const char *str;
365 char *op;
366 unsigned long val;
367 int line;
368
369 line = 0;
370 error = resource_find(&line, NULL, name, &unit, resname, NULL,
371 NULL, NULL, NULL, NULL, NULL, &str);
372 if (error)
373 return error;
374 if (*str == '\0')
375 return EFTYPE;
376 val = strtoul(str, &op, 0);
377 if (*op != '\0')
378 return EFTYPE;
379 *result = val;
380 return 0;
381 }
382
383 int
384 resource_string_value(const char *name, int unit, const char *resname,
385 const char **result)
386 {
387 int error;
388 const char *str;
389 int line;
390
391 line = 0;
392 error = resource_find(&line, NULL, name, &unit, resname, NULL,
393 NULL, NULL, NULL, NULL, NULL, &str);
394 if (error)
395 return error;
396 *result = str;
397 return 0;
398 }
399
400 /*
401 * This is a bit nasty, but allows us to not modify the env strings.
402 */
403 static const char *
404 resource_string_copy(const char *s, int len)
405 {
406 static char stringbuf[256];
407 static int offset = 0;
408 const char *ret;
409
410 if (len == 0)
411 len = strlen(s);
412 if (len > 255)
413 return NULL;
414 if ((offset + len + 1) > 255)
415 offset = 0;
416 bcopy(s, &stringbuf[offset], len);
417 stringbuf[offset + len] = '\0';
418 ret = &stringbuf[offset];
419 offset += len + 1;
420 return ret;
421 }
422
423 /*
424 * err = resource_find_match(&anchor, &name, &unit, resname, value)
425 * Iteratively fetch a list of devices wired "at" something
426 * res and value are restrictions. eg: "at", "scbus0".
427 * For practical purposes, res = required, value = optional.
428 * *name and *unit are set.
429 * set *anchor to zero before starting.
430 */
431 int
432 resource_find_match(int *anchor, const char **name, int *unit,
433 const char *resname, const char *value)
434 {
435 const char *found_name;
436 int found_namelen;
437 int found_unit;
438 int ret;
439 int newln;
440
441 newln = *anchor;
442 ret = resource_find(anchor, &newln, NULL, NULL, resname, value,
443 &found_name, &found_namelen, &found_unit, NULL, NULL, NULL);
444 if (ret == 0) {
445 *name = resource_string_copy(found_name, found_namelen);
446 *unit = found_unit;
447 }
448 *anchor = newln;
449 return ret;
450 }
451
452
453 /*
454 * err = resource_find_dev(&anchor, name, &unit, res, value);
455 * Iterate through a list of devices, returning their unit numbers.
456 * res and value are optional restrictions. eg: "at", "scbus0".
457 * *unit is set to the value.
458 * set *anchor to zero before starting.
459 */
460 int
461 resource_find_dev(int *anchor, const char *name, int *unit,
462 const char *resname, const char *value)
463 {
464 int found_unit;
465 int newln;
466 int ret;
467
468 newln = *anchor;
469 ret = resource_find(anchor, &newln, name, NULL, resname, value,
470 NULL, NULL, &found_unit, NULL, NULL, NULL);
471 if (ret == 0) {
472 *unit = found_unit;
473 }
474 *anchor = newln;
475 return ret;
476 }
477
478 /*
479 * Check to see if a device is disabled via a disabled hint.
480 */
481 int
482 resource_disabled(const char *name, int unit)
483 {
484 int error, value;
485
486 error = resource_int_value(name, unit, "disabled", &value);
487 if (error)
488 return (0);
489 return (value);
490 }
491
492 /*
493 * Clear a value associated with a device by removing it from
494 * the kernel environment. This only removes a hint for an
495 * exact unit.
496 */
497 int
498 resource_unset_value(const char *name, int unit, const char *resname)
499 {
500 char varname[128];
501 const char *retname, *retvalue;
502 int error, line;
503 size_t len;
504
505 line = 0;
506 error = resource_find(&line, NULL, name, &unit, resname, NULL,
507 &retname, NULL, NULL, NULL, NULL, &retvalue);
508 if (error)
509 return (error);
510
511 retname -= strlen("hint.");
512 len = retvalue - retname - 1;
513 if (len > sizeof(varname) - 1)
514 return (ENAMETOOLONG);
515 memcpy(varname, retname, len);
516 varname[len] = '\0';
517 return (kern_unsetenv(varname));
518 }
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