kern_environment.c revision 105354 
1/*-
2 * Copyright (c) 1998 Michael Smith
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: head/sys/kern/kern_environment.c 105354 2002-10-17 20:03:38Z robert $
27 */
28
29/*
30 * The unified bootloader passes us a pointer to a preserved copy of
31 * bootstrap/kernel environment variables.  We convert them to a
32 * dynamic array of strings later when the VM subsystem is up.
33 *
34 * We make these available through the kenv(2) syscall for userland
35 * and through getenv()/freeenv() setenv() unsetenv() testenv() for
36 * the kernel.
37 */
38
39#include <sys/types.h>
40#include <sys/param.h>
41#include <sys/proc.h>
42#include <sys/queue.h>
43#include <sys/lock.h>
44#include <sys/malloc.h>
45#include <sys/mutex.h>
46#include <sys/kernel.h>
47#include <sys/sx.h>
48#include <sys/systm.h>
49#include <sys/sysent.h>
50#include <sys/sysproto.h>
51#include <sys/libkern.h>
52#include <sys/kenv.h>
53
54MALLOC_DEFINE(M_KENV, "kenv", "kernel environment");
55
56#define KENV_SIZE	512	/* Maximum number of environment strings */
57
58/* pointer to the static environment */
59char		*kern_envp;
60static char	*kernenv_next(char *);
61
62/* dynamic environment variables */
63char		**kenvp;
64struct sx	kenv_lock;
65
66/*
67 * No need to protect this with a mutex
68 * since SYSINITS are single threaded.
69 */
70int	dynamic_kenv = 0;
71
72#define KENV_CHECK	if (!dynamic_kenv) \
73			    panic("%s: called before SI_SUB_KMEM", __func__)
74
75int
76kenv(td, uap)
77	struct thread *td;
78	struct kenv_args /* {
79		syscallarg(int) what;
80		syscallarg(const char *) name;
81		syscallarg(char *) value;
82		syscallarg(int) len;
83	} */ *uap;
84{
85	char *name, *value;
86	size_t len, done;
87	int error, i;
88
89	KASSERT(dynamic_kenv, ("kenv: dynamic_kenv = 0"));
90
91	error = 0;
92	if (SCARG(uap, what) == KENV_DUMP) {
93		len = 0;
94		/* Return the size if called with a NULL buffer */
95		if (SCARG(uap, value) == NULL) {
96			sx_slock(&kenv_lock);
97			for (i = 0; kenvp[i] != NULL; i++)
98				len += strlen(kenvp[i]) + 1;
99			sx_sunlock(&kenv_lock);
100			td->td_retval[0] = len;
101			return (0);
102		}
103		done = 0;
104		sx_slock(&kenv_lock);
105		for (i = 0; kenvp[i] != NULL && done < SCARG(uap, len); i++) {
106			len = min(strlen(kenvp[i]) + 1, SCARG(uap, len) - done);
107			error = copyout(kenvp[i], SCARG(uap, value) + done,
108			    len);
109			if (error) {
110				sx_sunlock(&kenv_lock);
111				return (error);
112			}
113			done += len;
114		}
115		sx_sunlock(&kenv_lock);
116		return (0);
117	}
118
119	if ((SCARG(uap, what) == KENV_SET) ||
120	    (SCARG(uap, what) == KENV_UNSET)) {
121		error = suser(td);
122		if (error)
123			return (error);
124	}
125
126	name = malloc(KENV_MNAMELEN, M_TEMP, M_WAITOK);
127
128	error = copyinstr(SCARG(uap, name), name, KENV_MNAMELEN, NULL);
129	if (error)
130		goto done;
131
132	switch (SCARG(uap, what)) {
133	case KENV_GET:
134		value = getenv(name);
135		if (value == NULL) {
136			error = ENOENT;
137			goto done;
138		}
139		len = strlen(value) + 1;
140		if (len > SCARG(uap, len))
141			len = SCARG(uap, len);
142		error = copyout(value, SCARG(uap, value), len);
143		freeenv(value);
144		if (error)
145			goto done;
146		td->td_retval[0] = len;
147		break;
148	case KENV_SET:
149		len = SCARG(uap, len);
150		if (len < 1) {
151			error = EINVAL;
152			goto done;
153		}
154		if (len > KENV_MVALLEN)
155			len = KENV_MVALLEN;
156		value = malloc(len, M_TEMP, M_WAITOK);
157		error = copyinstr(SCARG(uap, value), value, len, NULL);
158		if (error) {
159			free(value, M_TEMP);
160			goto done;
161		}
162		setenv(name, value);
163		free(value, M_TEMP);
164		break;
165	case KENV_UNSET:
166		error = unsetenv(name);
167		if (error)
168			error = ENOENT;
169		break;
170	default:
171		error = EINVAL;
172		break;
173	}
174done:
175	free(name, M_TEMP);
176	return (error);
177}
178
179/*
180 * Setup the dynamic kernel environment.
181 */
182static void
183init_dynamic_kenv(void *data __unused)
184{
185	char *cp;
186	int len, i;
187
188	kenvp = malloc(KENV_SIZE * sizeof(char *), M_KENV, M_WAITOK | M_ZERO);
189	i = 0;
190	for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
191		len = strlen(cp) + 1;
192		kenvp[i] = malloc(len, M_KENV, M_WAITOK);
193		strcpy(kenvp[i++], cp);
194	}
195	kenvp[i] = NULL;
196
197	sx_init(&kenv_lock, "kernel environment");
198	dynamic_kenv = 1;
199}
200SYSINIT(kenv, SI_SUB_KMEM, SI_ORDER_ANY, init_dynamic_kenv, NULL);
201
202void
203freeenv(char *env)
204{
205
206	if (dynamic_kenv)
207		free(env, M_KENV);
208}
209
210/*
211 * Internal functions for string lookup.
212 */
213static char *
214_getenv_dynamic(const char *name, int *idx)
215{
216	char *cp;
217	int len, i;
218
219	sx_assert(&kenv_lock, SX_LOCKED);
220	len = strlen(name);
221	for (cp = kenvp[0], i = 0; cp != NULL; cp = kenvp[++i]) {
222		if ((cp[len] == '=') &&
223		    (strncmp(cp, name, len) == 0)) {
224			if (idx != NULL)
225				*idx = i;
226			return (cp + len + 1);
227		}
228	}
229	return (NULL);
230}
231
232static char *
233_getenv_static(const char *name)
234{
235	char *cp, *ep;
236	int len;
237
238	for (cp = kern_envp; cp != NULL; cp = kernenv_next(cp)) {
239		for (ep = cp; (*ep != '=') && (*ep != 0); ep++)
240			;
241		if (*ep != '=')
242			continue;
243		len = ep - cp;
244		ep++;
245		if (!strncmp(name, cp, len) && name[len] == 0)
246			return (ep);
247	}
248	return (NULL);
249}
250
251/*
252 * Look up an environment variable by name.
253 * Return a pointer to the string if found.
254 * The pointer has to be freed with freeenv()
255 * after use.
256 */
257char *
258getenv(const char *name)
259{
260	char buf[KENV_MNAMELEN + 1 + KENV_MVALLEN + 1];
261	char *ret, *cp;
262	int len;
263
264	if (dynamic_kenv) {
265		sx_slock(&kenv_lock);
266		cp = _getenv_dynamic(name, NULL);
267		if (cp != NULL) {
268			strcpy(buf, cp);
269			sx_sunlock(&kenv_lock);
270			len = strlen(buf) + 1;
271			ret = malloc(len, M_KENV, M_WAITOK);
272			strcpy(ret, buf);
273		} else {
274			sx_sunlock(&kenv_lock);
275			ret = NULL;
276		}
277	} else
278		ret = _getenv_static(name);
279	return (ret);
280}
281
282/*
283 * Test if an environment variable is defined.
284 */
285int
286testenv(const char *name)
287{
288	char *cp;
289
290	if (dynamic_kenv) {
291		sx_slock(&kenv_lock);
292		cp = _getenv_dynamic(name, NULL);
293		sx_sunlock(&kenv_lock);
294	} else
295		cp = _getenv_static(name);
296	if (cp != NULL)
297		return (1);
298	return (0);
299}
300
301/*
302 * Set an environment variable by name.
303 */
304int
305setenv(const char *name, const char *value)
306{
307	char *buf, *cp, *oldenv;
308	int namelen, vallen, i;
309
310	KENV_CHECK;
311
312	namelen = strlen(name) + 1;
313	if (namelen > KENV_MNAMELEN)
314		return (-1);
315	vallen = strlen(value) + 1;
316	if (vallen > KENV_MVALLEN)
317		return (-1);
318	buf = malloc(namelen + vallen, M_KENV, M_WAITOK);
319	sprintf(buf, "%s=%s", name, value);
320
321	sx_xlock(&kenv_lock);
322	cp = _getenv_dynamic(name, &i);
323	if (cp != NULL) {
324		oldenv = kenvp[i];
325		kenvp[i] = buf;
326		sx_xunlock(&kenv_lock);
327		free(oldenv, M_KENV);
328	} else {
329		/* We add the option if it wasn't found */
330		for (i = 0; (cp = kenvp[i]) != NULL; i++)
331			;
332		kenvp[i] = buf;
333		kenvp[i + 1] = NULL;
334		sx_xunlock(&kenv_lock);
335	}
336	return (0);
337}
338
339/*
340 * Unset an environment variable string.
341 */
342int
343unsetenv(const char *name)
344{
345	char *cp, *oldenv;
346	int i, j;
347
348	KENV_CHECK;
349
350	sx_xlock(&kenv_lock);
351	cp = _getenv_dynamic(name, &i);
352	if (cp != NULL) {
353		oldenv = kenvp[i];
354		for (j = i + 1; kenvp[j] != NULL; j++)
355			kenvp[i++] = kenvp[j];
356		kenvp[i] = NULL;
357		sx_xunlock(&kenv_lock);
358		free(oldenv, M_KENV);
359		return (0);
360	}
361	sx_xunlock(&kenv_lock);
362	return (-1);
363}
364
365/*
366 * Return a string value from an environment variable.
367 */
368int
369getenv_string(const char *name, char *data, int size)
370{
371	char *tmp;
372
373	tmp = getenv(name);
374	if (tmp != NULL) {
375		strlcpy(data, tmp, size);
376		freeenv(tmp);
377		return (1);
378	} else
379		return (0);
380}
381
382/*
383 * Return an integer value from an environment variable.
384 */
385int
386getenv_int(const char *name, int *data)
387{
388	quad_t tmp;
389	int rval;
390
391	rval = getenv_quad(name, &tmp);
392	if (rval)
393		*data = (int) tmp;
394	return (rval);
395}
396
397/*
398 * Return a quad_t value from an environment variable.
399 */
400int
401getenv_quad(const char *name, quad_t *data)
402{
403	char	*value;
404	char	*vtp;
405	quad_t	iv;
406
407	value = getenv(name);
408	if (value == NULL)
409		return (0);
410	iv = strtoq(value, &vtp, 0);
411	if ((vtp == value) || (*vtp != '\0')) {
412		freeenv(value);
413		return (0);
414	}
415	freeenv(value);
416	*data = iv;
417	return (1);
418}
419
420/*
421 * Find the next entry after the one which (cp) falls within, return a
422 * pointer to its start or NULL if there are no more.
423 */
424static char *
425kernenv_next(char *cp)
426{
427
428	if (cp != NULL) {
429		while (*cp != 0)
430			cp++;
431		cp++;
432		if (*cp == 0)
433			cp = NULL;
434	}
435	return (cp);
436}
437
438void
439tunable_int_init(void *data)
440{
441	struct tunable_int *d = (struct tunable_int *)data;
442
443	TUNABLE_INT_FETCH(d->path, d->var);
444}
445
446void
447tunable_quad_init(void *data)
448{
449	struct tunable_quad *d = (struct tunable_quad *)data;
450
451	TUNABLE_QUAD_FETCH(d->path, d->var);
452}
453
454void
455tunable_str_init(void *data)
456{
457	struct tunable_str *d = (struct tunable_str *)data;
458
459	TUNABLE_STR_FETCH(d->path, d->var, d->size);
460}
461