1/*-
2 * Copyright (c) 2008 Robert N. M. Watson
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
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD$");
29
30#include <sys/types.h>
31#include <sys/sysctl.h>
32
33#include <err.h>
34#include <errno.h>
35#include <fcntl.h>
36#include <kvm.h>
37#include <limits.h>
38#include <stdio.h>
39#include <stdlib.h>
40#include <string.h>
41#include <sysexits.h>
42#include <unistd.h>
43
44#include "ddb.h"
45
46/*
47 * Interface with the ddb(4) capture buffer of a live kernel using sysctl, or
48 * for a crash dump using libkvm.
49 */
50#define	SYSCTL_DDB_CAPTURE_BUFOFF	"debug.ddb.capture.bufoff"
51#define	SYSCTL_DDB_CAPTURE_BUFSIZE	"debug.ddb.capture.bufsize"
52#define	SYSCTL_DDB_CAPTURE_MAXBUFSIZE	"debug.ddb.capture.maxbufsize"
53#define	SYSCTL_DDB_CAPTURE_DATA		"debug.ddb.capture.data"
54#define	SYSCTL_DDB_CAPTURE_INPROGRESS	"debug.ddb.capture.inprogress"
55
56static struct nlist namelist[] = {
57#define X_DB_CAPTURE_BUF	0
58	{ .n_name = "_db_capture_buf" },
59#define X_DB_CAPTURE_BUFSIZE	1
60	{ .n_name = "_db_capture_bufsize" },
61#define X_DB_CAPTURE_MAXBUFSIZE	2
62	{ .n_name = "_db_capture_maxbufsize" },
63#define X_DB_CAPTURE_BUFOFF	3
64	{ .n_name = "_db_capture_bufoff" },
65#define	X_DB_CAPTURE_INPROGRESS	4
66	{ .n_name = "_db_capture_inprogress" },
67	{ .n_name = "" },
68};
69
70static int
71kread(kvm_t *kvm, void *kvm_pointer, void *address, size_t size,
72    size_t offset)
73{
74	ssize_t ret;
75
76	ret = kvm_read(kvm, (unsigned long)kvm_pointer + offset, address,
77	    size);
78	if (ret < 0 || (size_t)ret != size)
79		return (-1);
80	return (0);
81}
82
83static int
84kread_symbol(kvm_t *kvm, int index, void *address, size_t size,
85    size_t offset)
86{
87	ssize_t ret;
88
89	ret = kvm_read(kvm, namelist[index].n_value + offset, address, size);
90	if (ret < 0 || (size_t)ret != size)
91		return (-1);
92	return (0);
93}
94
95static void
96ddb_capture_print_kvm(kvm_t *kvm)
97{
98	u_int db_capture_bufoff;
99	char *buffer, *db_capture_buf;
100
101	if (kread_symbol(kvm, X_DB_CAPTURE_BUF, &db_capture_buf,
102	    sizeof(db_capture_buf), 0) < 0)
103		errx(-1, "kvm: unable to read db_capture_buf");
104
105	if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
106	    sizeof(db_capture_bufoff), 0) < 0)
107		errx(-1, "kvm: unable to read db_capture_bufoff");
108
109	buffer = malloc(db_capture_bufoff + 1);
110	if (buffer == NULL)
111		err(-1, "malloc: db_capture_bufoff (%u)",
112		    db_capture_bufoff);
113	bzero(buffer, db_capture_bufoff + 1);
114
115	if (kread(kvm, db_capture_buf, buffer, db_capture_bufoff, 0) < 0)
116		errx(-1, "kvm: unable to read buffer");
117
118	printf("%s\n", buffer);
119	free(buffer);
120}
121
122static void
123ddb_capture_print_sysctl(void)
124{
125	size_t buflen, len;
126	char *buffer;
127	int ret;
128
129repeat:
130	if (sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, NULL, &buflen, NULL, 0) < 0)
131		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
132	if (buflen == 0)
133		return;
134	buffer = malloc(buflen);
135	if (buffer == NULL)
136		err(EX_OSERR, "malloc");
137	bzero(buffer, buflen);
138	len = buflen;
139	ret = sysctlbyname(SYSCTL_DDB_CAPTURE_DATA, buffer, &len, NULL, 0);
140	if (ret < 0 && errno != ENOMEM)
141		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_DATA);
142	if (ret < 0) {
143		free(buffer);
144		goto repeat;
145	}
146
147	printf("%s\n", buffer);
148	free(buffer);
149}
150
151static void
152ddb_capture_status_kvm(kvm_t *kvm)
153{
154	u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
155
156	if (kread_symbol(kvm, X_DB_CAPTURE_BUFOFF, &db_capture_bufoff,
157	    sizeof(db_capture_bufoff), 0) < 0)
158		errx(-1, "kvm: unable to read db_capture_bufoff");
159	if (kread_symbol(kvm, X_DB_CAPTURE_BUFSIZE, &db_capture_bufsize,
160	    sizeof(db_capture_bufsize), 0) < 0)
161		errx(-1, "kvm: unable to read db_capture_bufsize");
162	if (kread_symbol(kvm, X_DB_CAPTURE_INPROGRESS,
163	    &db_capture_inprogress, sizeof(db_capture_inprogress), 0) < 0)
164		err(-1, "kvm: unable to read db_capture_inprogress");
165	printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
166	if (db_capture_inprogress)
167		printf("capture is on\n");
168	else
169		printf("capture is off\n");
170
171}
172
173static void
174ddb_capture_status_sysctl(void)
175{
176	u_int db_capture_bufoff, db_capture_bufsize, db_capture_inprogress;
177	size_t len;
178
179	len = sizeof(db_capture_bufoff);
180	if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFOFF, &db_capture_bufoff, &len,
181	    NULL, 0) < 0)
182		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFOFF);
183	len = sizeof(db_capture_bufoff);
184	if (sysctlbyname(SYSCTL_DDB_CAPTURE_BUFSIZE, &db_capture_bufsize,
185	    &len, NULL, 0) < 0)
186		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_BUFSIZE);
187	len = sizeof(db_capture_inprogress);
188	if (sysctlbyname(SYSCTL_DDB_CAPTURE_INPROGRESS,
189	    &db_capture_inprogress, &len, NULL, 0) < 0)
190		err(EX_OSERR, "sysctl: %s", SYSCTL_DDB_CAPTURE_INPROGRESS);
191	printf("%u/%u bytes used\n", db_capture_bufoff, db_capture_bufsize);
192	if (db_capture_inprogress)
193		printf("capture is on\n");
194	else
195		printf("capture is off\n");
196}
197
198void
199ddb_capture(int argc, char *argv[])
200{
201	char *mflag, *nflag, errbuf[_POSIX2_LINE_MAX];
202	kvm_t *kvm;
203	int ch;
204
205	mflag = NULL;
206	nflag = NULL;
207	kvm = NULL;
208	while ((ch = getopt(argc, argv, "M:N:")) != -1) {
209		switch (ch) {
210		case 'M':
211			mflag = optarg;
212			break;
213
214		case 'N':
215			nflag = optarg;
216			break;
217
218		default:
219			usage();
220		}
221	}
222	argc -= optind;
223	argv += optind;
224
225	if (argc != 1)
226		usage();
227
228	if (mflag != NULL) {
229		kvm = kvm_openfiles(nflag, mflag, NULL, O_RDONLY, errbuf);
230		if (kvm == NULL)
231			errx(-1, "ddb_capture: kvm_openfiles: %s", errbuf);
232		if (kvm_nlist(kvm, namelist) != 0)
233			errx(-1, "ddb_capture: kvm_nlist");
234	} else if (nflag != NULL)
235		usage();
236	if (strcmp(argv[0], "print") == 0) {
237		if (kvm != NULL)
238			ddb_capture_print_kvm(kvm);
239		else
240			ddb_capture_print_sysctl();
241	} else if (strcmp(argv[0], "status") == 0) {
242		if (kvm != NULL)
243			ddb_capture_status_kvm(kvm);
244		else
245			ddb_capture_status_sysctl();
246	} else
247		usage();
248}
249