path: root/util-linux/dmesg.c (plain)
blob: ba52036a701f744a88bbcd834053b4ebb43d5927

1	/* vi: set sw=4 ts=4: */
2	/*
3	*
4	* dmesg - display/control kernel ring buffer.
5	*
6	* Copyright 2006 Rob Landley <rob@landley.net>
7	* Copyright 2006 Bernhard Reutner-Fischer <rep.nop@aon.at>
8	*
9	* Licensed under GPLv2, see file LICENSE in this source tree.
10	*/
11
12	//usage:#define dmesg_trivial_usage
13	//usage: "[-c] [-n LEVEL] [-s SIZE]"
14	//usage: IF_FEATURE_DMESG_PRETTY(" [-r]")
15	//usage: IF_FEATURE_DMESG_COLOR(" [-C]")
16	//usage:#define dmesg_full_usage "\n\n"
17	//usage: "Print or control the kernel ring buffer\n"
18	//usage: "\n -c Clear ring buffer after printing"
19	//usage: "\n -n LEVEL Set console logging level"
20	//usage: "\n -s SIZE Buffer size"
21	//usage: IF_FEATURE_DMESG_PRETTY(
22	//usage: "\n -r Show level prefix")
23	//usage: IF_FEATURE_DMESG_COLOR(
24	//usage: "\n -C Colored output")
25
26	#include <sys/klog.h>
27	#include "libbb.h"
28
29	#if ENABLE_FEATURE_DMESG_COLOR
30	#define COLOR_DEFAULT 0
31	#define COLOR_WHITE 97
32	#define COLOR_YELLOW 93
33	#define COLOR_ORANGE 33
34	#define COLOR_RED 91
35
36	static void set_color(int color)
37	{
38	printf("%c[%dm", 0x1B, color);
39	}
40
41	#else
42	#define set_color(c) {}
43	#endif
44
45	int dmesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
46	int dmesg_main(int argc UNUSED_PARAM, char **argv)
47	{
48	int len, level;
49	char *buf;
50	unsigned opts;
51	int color = 0;
52	enum {
53	OPT_c = 1 << 0,
54	OPT_s = 1 << 1,
55	OPT_n = 1 << 2,
56	OPT_r = 1 << 3,
57	OPT_C = 1 << 4,
58	OPT_end
59	};
60
61	opt_complementary = "s+:n+"; /* numeric */
62	opts = getopt32(argv, "cs:n:rC", &len, &level);
63	if (opts & OPT_n) {
64	if (klogctl(8, NULL, (long) level))
65	bb_perror_msg_and_die("klogctl");
66	return EXIT_SUCCESS;
67	}
68
69	if (!(opts & OPT_s))
70	len = klogctl(10, NULL, 0); /* read ring buffer size */
71	if (len < 16*1024)
72	len = 16*1024;
73	if (len > 16*1024*1024)
74	len = 16*1024*1024;
75
76	buf = xmalloc(len);
77	len = klogctl(3 + (opts & OPT_c), buf, len); /* read ring buffer */
78	if (len < 0)
79	bb_perror_msg_and_die("klogctl");
80	if (len == 0)
81	return EXIT_SUCCESS;
82
83
84	if ((ENABLE_FEATURE_DMESG_PRETTY || (opts & OPT_C)) && !(opts & OPT_r)) {
85	int last = '\n';
86	int in = 0;
87
88	/* Skip <[0-9]+> at the start of lines */
89	while (1) {
90	if (last == '\n' && buf[in] == '<') {
91
92	#if ENABLE_FEATURE_DMESG_COLOR
93	if (opts & OPT_C) {
94	char *lvl = buf + in + 1;
95	sscanf(lvl, "%d", &level);
96
97	switch (level) {
98	case 1:
99	case 2:
100	case 3: color = COLOR_RED; break;
101	case 4: color = COLOR_ORANGE; break;
102	case 5: color = COLOR_YELLOW; break;
103	case 7: color = COLOR_WHITE; break;
104	case 6: /* common dmesg info */
105	default:
106	color = COLOR_DEFAULT;
107	}
108
109	set_color(color);
110	}
111	#endif
112	while (buf[in++] != '>' && in < len)
113	;
114	} else {
115	last = buf[in++];
116	putchar(last);
117	}
118	if (in >= len)
119	break;
120	}
121	/* Make sure we end with a newline */
122	if (last != '\n')
123	bb_putchar('\n');
124	} else {
125	full_write(STDOUT_FILENO, buf, len);
126	if (buf[len-1] != '\n')
127	bb_putchar('\n');
128	}
129
130	if (ENABLE_FEATURE_CLEAN_UP) free(buf);
131
132	/* Reset default terminal color */
133	if (color)
134	set_color(0);
135
136	return EXIT_SUCCESS;
137	}
138