aboutsummaryrefslogtreecommitdiff
path: root/dmesg.c
blob: e88f549cafcc82eacbd171e1043374922d1a3092 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
/* vi: set sw=4 ts=4: */
/* dmesg.c -- Print out the contents of the kernel ring buffer
 * Created: Sat Oct  9 16:19:47 1993
 * Revised: Thu Oct 28 21:52:17 1993 by faith@cs.unc.edu
 * Copyright 1993 Theodore Ts'o (tytso@athena.mit.edu)
 * This program comes with ABSOLUTELY NO WARRANTY.
 * Modifications by Rick Sladkey (jrs@world.std.com)
 * Larger buffersize 3 June 1998 by Nicolai Langfeldt, based on a patch
 * by Peeter Joot.  This was also suggested by John Hudson.
 * 1999-02-22 Arkadiusz Mi�kiewicz <misiek@misiek.eu.org>
 * - added Native Language Support
 *
 * from util-linux -- adapted for busybox by 
 * Erik Andersen <andersee@debian.org>. I ripped out Native Language 
 * Support, replaced getopt, added some gotos for redundant stuff.
 */

#include "internal.h"
#include <stdio.h>
#include <stdlib.h>

#if __GNU_LIBRARY__ < 5

#ifndef __alpha__
# define __NR_klogctl __NR_syslog
#include <linux/unistd.h>
static inline _syscall3(int, klogctl, int, type, char *, b, int, len);
#else							/* __alpha__ */
#define klogctl syslog
#endif

#else
# include <sys/klog.h>
#endif

static const char dmesg_usage[] = "dmesg [-c] [-n LEVEL] [-s SIZE]\n"
#ifndef BB_FEATURE_TRIVIAL_HELP
	"\nPrints or controls the kernel ring buffer\n\n"
	"Options:\n"
	"\t-c\t\tClears the ring buffer's contents after printing\n"
	"\t-n LEVEL\tSets console logging level\n"
	"\t-s SIZE\t\tUse a buffer of size SIZE\n"
#endif
	;

int dmesg_main(int argc, char **argv)
{
	char *buf;
	int bufsize = 8196;
	int i;
	int n;
	int level = 0;
	int lastc;
	int cmd = 3;
	int stopDoingThat;

	argc--;
	argv++;

	/* Parse any options */
	while (argc && **argv == '-') {
		stopDoingThat = FALSE;
		while (stopDoingThat == FALSE && *++(*argv)) {
			switch (**argv) {
			case 'c':
				cmd = 4;
				break;
			case 'n':
				cmd = 8;
				if (--argc == 0)
					goto end;
				level = atoi(*(++argv));
				if (--argc > 0)
					++argv;
				stopDoingThat = TRUE;
				break;
			case 's':
				if (--argc == 0)
					goto end;
				bufsize = atoi(*(++argv));
				if (--argc > 0)
					++argv;
				stopDoingThat = TRUE;
				break;
			default:
				goto end;
			}
		}
	}

	if (argc > 1) {
		goto end;
	}

	if (cmd == 8) {
		n = klogctl(cmd, NULL, level);
		if (n < 0) {
			goto klogctl_error;
		}
		exit(TRUE);
	}

	if (bufsize < 4096)
		bufsize = 4096;
	buf = (char *) xmalloc(bufsize);
	n = klogctl(cmd, buf, bufsize);
	if (n < 0) {
		goto klogctl_error;
	}

	lastc = '\n';
	for (i = 0; i < n; i++) {
		if ((i == 0 || buf[i - 1] == '\n') && buf[i] == '<') {
			i++;
			while (buf[i] >= '0' && buf[i] <= '9')
				i++;
			if (buf[i] == '>')
				i++;
		}
		lastc = buf[i];
		putchar(lastc);
	}
	if (lastc != '\n')
		putchar('\n');
	exit(TRUE);
  end:
	usage(dmesg_usage);
	exit(FALSE);
  klogctl_error:
	perror("klogctl");
	return(FALSE);
}