xref: /illumos-gate/usr/src/lib/libkstat/common/kstat.c (revision c0e96d86)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  * Copyright 2015 Nexenta Systems, Inc. All rights reserved.
26  */
27 
28 #include <stdio.h>
29 #include <stdlib.h>
30 #include <stdarg.h>
31 #include <ctype.h>
32 #include <unistd.h>
33 #include <memory.h>
34 #include <strings.h>
35 #include <string.h>
36 #include <fcntl.h>
37 #include <errno.h>
38 #include <poll.h>
39 #include "kstat.h"
40 
41 /*LINTLIBRARY*/
42 
43 static void
kstat_zalloc(void ** ptr,size_t size,int free_first)44 kstat_zalloc(void **ptr, size_t size, int free_first)
45 {
46 	if (free_first)
47 		free(*ptr);
48 	*ptr = calloc(size, 1);
49 }
50 
51 static void
kstat_chain_free(kstat_ctl_t * kc)52 kstat_chain_free(kstat_ctl_t *kc)
53 {
54 	kstat_t *ksp, *nksp;
55 
56 	ksp = kc->kc_chain;
57 	while (ksp) {
58 		nksp = ksp->ks_next;
59 		free(ksp->ks_data);
60 		free(ksp);
61 		ksp = nksp;
62 	}
63 	kc->kc_chain = NULL;
64 	kc->kc_chain_id = 0;
65 }
66 
67 kstat_ctl_t *
kstat_open(void)68 kstat_open(void)
69 {
70 	kstat_ctl_t *kc;
71 	int kd;
72 
73 	kd = open("/dev/kstat", O_RDONLY);
74 	if (kd == -1)
75 		return (NULL);
76 	kstat_zalloc((void **)&kc, sizeof (kstat_ctl_t), 0);
77 	if (kc == NULL)
78 		return (NULL);
79 
80 	kc->kc_kd = kd;
81 	kc->kc_chain = NULL;
82 	kc->kc_chain_id = 0;
83 	if (kstat_chain_update(kc) == -1) {
84 		int saved_err = errno;
85 		(void) kstat_close(kc);
86 		errno = saved_err;
87 		return (NULL);
88 	}
89 	return (kc);
90 }
91 
92 int
kstat_close(kstat_ctl_t * kc)93 kstat_close(kstat_ctl_t *kc)
94 {
95 	int rc;
96 
97 	kstat_chain_free(kc);
98 	rc = close(kc->kc_kd);
99 	free(kc);
100 	return (rc);
101 }
102 
103 kid_t
kstat_read(kstat_ctl_t * kc,kstat_t * ksp,void * data)104 kstat_read(kstat_ctl_t *kc, kstat_t *ksp, void *data)
105 {
106 	kid_t kcid;
107 
108 	if (ksp->ks_data == NULL && ksp->ks_data_size > 0) {
109 		kstat_zalloc(&ksp->ks_data, ksp->ks_data_size, 0);
110 		if (ksp->ks_data == NULL)
111 			return (-1);
112 	}
113 	while ((kcid = (kid_t)ioctl(kc->kc_kd, KSTAT_IOC_READ, ksp)) == -1) {
114 		if (errno == EAGAIN) {
115 			(void) poll(NULL, 0, 100);	/* back off a moment */
116 			continue;			/* and try again */
117 		}
118 		/*
119 		 * Mating dance for variable-size kstats.
120 		 * You start with a buffer of a certain size,
121 		 * which you hope will hold all the data.
122 		 * If your buffer is too small, the kstat driver
123 		 * returns ENOMEM and sets ksp->ks_data_size to
124 		 * the current size of the kstat's data.  You then
125 		 * resize your buffer and try again.  In practice,
126 		 * this almost always converges in two passes.
127 		 */
128 		if (errno == ENOMEM && (ksp->ks_flags &
129 		    (KSTAT_FLAG_VAR_SIZE | KSTAT_FLAG_LONGSTRINGS))) {
130 			kstat_zalloc(&ksp->ks_data, ksp->ks_data_size, 1);
131 			if (ksp->ks_data != NULL)
132 				continue;
133 		}
134 		return (-1);
135 	}
136 	if (data != NULL) {
137 		(void) memcpy(data, ksp->ks_data, ksp->ks_data_size);
138 		if (ksp->ks_type == KSTAT_TYPE_NAMED &&
139 		    ksp->ks_data_size !=
140 		    ksp->ks_ndata * sizeof (kstat_named_t)) {
141 			/*
142 			 * Has KSTAT_DATA_STRING fields. Fix the pointers.
143 			 */
144 			uint_t i;
145 			kstat_named_t *knp = data;
146 
147 			for (i = 0; i < ksp->ks_ndata; i++, knp++) {
148 				if (knp->data_type != KSTAT_DATA_STRING)
149 					continue;
150 				if (KSTAT_NAMED_STR_PTR(knp) == NULL)
151 					continue;
152 				/*
153 				 * The offsets of the strings within the
154 				 * buffers are the same, so add the offset of
155 				 * the string to the beginning of 'data' to fix
156 				 * the pointer so that strings in 'data' don't
157 				 * point at memory in 'ksp->ks_data'.
158 				 */
159 				KSTAT_NAMED_STR_PTR(knp) = (char *)data +
160 				    (KSTAT_NAMED_STR_PTR(knp) -
161 				    (char *)ksp->ks_data);
162 			}
163 		}
164 	}
165 	return (kcid);
166 }
167 
168 kid_t
kstat_write(kstat_ctl_t * kc,kstat_t * ksp,void * data)169 kstat_write(kstat_ctl_t *kc, kstat_t *ksp, void *data)
170 {
171 	kid_t kcid;
172 
173 	if (ksp->ks_data == NULL && ksp->ks_data_size > 0) {
174 		kstat_zalloc(&ksp->ks_data, ksp->ks_data_size, 0);
175 		if (ksp->ks_data == NULL)
176 			return (-1);
177 	}
178 	if (data != NULL) {
179 		(void) memcpy(ksp->ks_data, data, ksp->ks_data_size);
180 		if (ksp->ks_type == KSTAT_TYPE_NAMED) {
181 			kstat_named_t *oknp = data;
182 			kstat_named_t *nknp = KSTAT_NAMED_PTR(ksp);
183 			uint_t i;
184 
185 			for (i = 0; i < ksp->ks_ndata; i++, oknp++, nknp++) {
186 				if (nknp->data_type != KSTAT_DATA_STRING)
187 					continue;
188 				if (KSTAT_NAMED_STR_PTR(nknp) == NULL)
189 					continue;
190 				/*
191 				 * The buffer passed in as 'data' has string
192 				 * pointers that point within 'data'.  Fix the
193 				 * pointers so they point into the same offset
194 				 * within the newly allocated buffer.
195 				 */
196 				KSTAT_NAMED_STR_PTR(nknp) =
197 				    (char *)ksp->ks_data +
198 				    (KSTAT_NAMED_STR_PTR(oknp) - (char *)data);
199 			}
200 		}
201 
202 	}
203 	while ((kcid = (kid_t)ioctl(kc->kc_kd, KSTAT_IOC_WRITE, ksp)) == -1) {
204 		if (errno == EAGAIN) {
205 			(void) poll(NULL, 0, 100);	/* back off a moment */
206 			continue;			/* and try again */
207 		}
208 		break;
209 	}
210 	return (kcid);
211 }
212 
213 /*
214  * If the current KCID is the same as kc->kc_chain_id, return 0;
215  * if different, update the chain and return the new KCID.
216  * This operation is non-destructive for unchanged kstats.
217  */
218 kid_t
kstat_chain_update(kstat_ctl_t * kc)219 kstat_chain_update(kstat_ctl_t *kc)
220 {
221 	kstat_t k0, *headers, *oksp, *nksp, **okspp, *next;
222 	int i;
223 	kid_t kcid;
224 
225 	kcid = (kid_t)ioctl(kc->kc_kd, KSTAT_IOC_CHAIN_ID, NULL);
226 	if (kcid == -1)
227 		return (-1);
228 	if (kcid == kc->kc_chain_id)
229 		return (0);
230 
231 	/*
232 	 * kstat 0's data is the kstat chain, so we can get the chain
233 	 * by doing a kstat_read() of this kstat.  The only fields the
234 	 * kstat driver needs are ks_kid (this identifies the kstat),
235 	 * ks_data (the pointer to our buffer), and ks_data_size (the
236 	 * size of our buffer).  By zeroing the struct we set ks_data = NULL
237 	 * and ks_data_size = 0, so that kstat_read() will automatically
238 	 * determine the size and allocate space for us.  We also fill in the
239 	 * name, so that truss can print something meaningful.
240 	 */
241 	bzero(&k0, sizeof (k0));
242 	(void) strcpy(k0.ks_name, "kstat_headers");
243 
244 	kcid = kstat_read(kc, &k0, NULL);
245 	if (kcid == -1) {
246 		free(k0.ks_data);
247 		/* errno set by kstat_read() */
248 		return (-1);
249 	}
250 	headers = k0.ks_data;
251 
252 	/*
253 	 * Chain the new headers together
254 	 */
255 	for (i = 1; i < k0.ks_ndata; i++)
256 		headers[i - 1].ks_next = &headers[i];
257 
258 	headers[k0.ks_ndata - 1].ks_next = NULL;
259 
260 	/*
261 	 * Remove all deleted kstats from the chain.
262 	 */
263 	nksp = headers;
264 	okspp = &kc->kc_chain;
265 	oksp = kc->kc_chain;
266 	while (oksp != NULL) {
267 		next = oksp->ks_next;
268 		if (nksp != NULL && oksp->ks_kid == nksp->ks_kid) {
269 			okspp = &oksp->ks_next;
270 			nksp = nksp->ks_next;
271 		} else {
272 			*okspp = oksp->ks_next;
273 			free(oksp->ks_data);
274 			free(oksp);
275 		}
276 		oksp = next;
277 	}
278 
279 	/*
280 	 * Add all new kstats to the chain.
281 	 */
282 	while (nksp != NULL) {
283 		kstat_zalloc((void **)okspp, sizeof (kstat_t), 0);
284 		if ((oksp = *okspp) == NULL) {
285 			free(headers);
286 			return (-1);
287 		}
288 		*oksp = *nksp;
289 		okspp = &oksp->ks_next;
290 		oksp->ks_next = NULL;
291 		oksp->ks_data = NULL;
292 		nksp = nksp->ks_next;
293 	}
294 
295 	free(headers);
296 	kc->kc_chain_id = kcid;
297 	return (kcid);
298 }
299 
300 kstat_t *
kstat_lookup(kstat_ctl_t * kc,char * ks_module,int ks_instance,char * ks_name)301 kstat_lookup(kstat_ctl_t *kc, char *ks_module, int ks_instance, char *ks_name)
302 {
303 	kstat_t *ksp;
304 
305 	for (ksp = kc->kc_chain; ksp; ksp = ksp->ks_next) {
306 		if ((ks_module == NULL ||
307 		    strcmp(ksp->ks_module, ks_module) == 0) &&
308 		    (ks_instance == -1 || ksp->ks_instance == ks_instance) &&
309 		    (ks_name == NULL || strcmp(ksp->ks_name, ks_name) == 0))
310 			return (ksp);
311 	}
312 
313 	errno = ENOENT;
314 	return (NULL);
315 }
316 
317 void *
kstat_data_lookup(kstat_t * ksp,char * name)318 kstat_data_lookup(kstat_t *ksp, char *name)
319 {
320 	int i, size;
321 	char *namep, *datap;
322 
323 	switch (ksp->ks_type) {
324 
325 	case KSTAT_TYPE_NAMED:
326 		size = sizeof (kstat_named_t);
327 		namep = KSTAT_NAMED_PTR(ksp)->name;
328 		break;
329 
330 	case KSTAT_TYPE_TIMER:
331 		size = sizeof (kstat_timer_t);
332 		namep = KSTAT_TIMER_PTR(ksp)->name;
333 		break;
334 
335 	default:
336 		errno = EINVAL;
337 		return (NULL);
338 	}
339 
340 	datap = ksp->ks_data;
341 	for (i = 0; i < ksp->ks_ndata; i++) {
342 		if (strcmp(name, namep) == 0)
343 			return (datap);
344 		namep += size;
345 		datap += size;
346 	}
347 	errno = ENOENT;
348 	return (NULL);
349 }
350