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Erik Andersene49d5ec2000-02-08 19:58:47 +00001/* vi: set sw=4 ts=4: */
Eric Andersencc8ed391999-10-05 16:24:54 +00002/* dmesg.c -- Print out the contents of the kernel ring buffer
3 * Created: Sat Oct 9 16:19:47 1993
4 * Revised: Thu Oct 28 21:52:17 1993 by faith@cs.unc.edu
5 * Copyright 1993 Theodore Ts'o (tytso@athena.mit.edu)
6 * This program comes with ABSOLUTELY NO WARRANTY.
7 * Modifications by Rick Sladkey (jrs@world.std.com)
Eric Andersene77ae3a1999-10-19 20:03:34 +00008 * Larger buffersize 3 June 1998 by Nicolai Langfeldt, based on a patch
9 * by Peeter Joot. This was also suggested by John Hudson.
10 * 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@misiek.eu.org>
11 * - added Native Language Support
12 *
13 * from util-linux -- adapted for busybox by
14 * Erik Andersen <andersee@debian.org>. I ripped out Native Language
15 * Support, replaced getopt, added some gotos for redundant stuff.
Eric Andersencc8ed391999-10-05 16:24:54 +000016 */
17
Eric Andersene77ae3a1999-10-19 20:03:34 +000018#include "internal.h"
Eric Andersencc8ed391999-10-05 16:24:54 +000019#include <linux/unistd.h>
20#include <stdio.h>
Eric Andersene77ae3a1999-10-19 20:03:34 +000021#include <stdlib.h>
Eric Andersencc8ed391999-10-05 16:24:54 +000022
Eric Andersene77ae3a1999-10-19 20:03:34 +000023#if __GNU_LIBRARY__ < 5
Eric Andersencc8ed391999-10-05 16:24:54 +000024
Eric Andersene77ae3a1999-10-19 20:03:34 +000025#ifndef __alpha__
26# define __NR_klogctl __NR_syslog
Erik Andersene49d5ec2000-02-08 19:58:47 +000027static inline _syscall3(int, klogctl, int, type, char *, b, int, len);
28#else /* __alpha__ */
Eric Andersene77ae3a1999-10-19 20:03:34 +000029#define klogctl syslog
30#endif
31
Eric Andersencc8ed391999-10-05 16:24:54 +000032#else
Eric Andersene77ae3a1999-10-19 20:03:34 +000033# include <sys/klog.h>
34#endif
Eric Andersencc8ed391999-10-05 16:24:54 +000035
Erik Andersen59b9e872000-05-10 05:05:45 +000036static const char dmesg_usage[] = "dmesg [-c] [-n LEVEL] [-s SIZE]\n"
37#ifndef BB_FEATURE_TRIVIAL_HELP
38 "\nPrints or controls the kernel ring buffer\n\n"
39 "Options:\n"
40 "\t-c\t\tClears the ring buffer's contents after printing\n"
41 "\t-n LEVEL\tSets console logging level\n"
42 "\t-s SIZE\t\tUse a buffer of size SIZE\n"
43#endif
44 ;
Eric Andersencc8ed391999-10-05 16:24:54 +000045
Erik Andersene49d5ec2000-02-08 19:58:47 +000046int dmesg_main(int argc, char **argv)
Eric Andersencc8ed391999-10-05 16:24:54 +000047{
Erik Andersene49d5ec2000-02-08 19:58:47 +000048 char *buf;
49 int bufsize = 8196;
50 int i;
51 int n;
52 int level = 0;
53 int lastc;
54 int cmd = 3;
55 int stopDoingThat;
Erik Andersen1266a131999-12-29 22:19:46 +000056
Erik Andersene49d5ec2000-02-08 19:58:47 +000057 argc--;
58 argv++;
Eric Andersencc8ed391999-10-05 16:24:54 +000059
Erik Andersene49d5ec2000-02-08 19:58:47 +000060 /* Parse any options */
61 while (argc && **argv == '-') {
62 stopDoingThat = FALSE;
63 while (stopDoingThat == FALSE && *++(*argv)) {
64 switch (**argv) {
65 case 'c':
66 cmd = 4;
67 break;
68 case 'n':
69 cmd = 8;
70 if (--argc == 0)
71 goto end;
72 level = atoi(*(++argv));
73 if (--argc > 0)
74 ++argv;
75 stopDoingThat = TRUE;
76 break;
77 case 's':
78 if (--argc == 0)
79 goto end;
80 bufsize = atoi(*(++argv));
81 if (--argc > 0)
82 ++argv;
83 stopDoingThat = TRUE;
84 break;
85 default:
86 goto end;
87 }
88 }
Erik Andersen1266a131999-12-29 22:19:46 +000089 }
Eric Andersencc8ed391999-10-05 16:24:54 +000090
Erik Andersene49d5ec2000-02-08 19:58:47 +000091 if (argc > 1) {
92 goto end;
93 }
Eric Andersencc8ed391999-10-05 16:24:54 +000094
Erik Andersene49d5ec2000-02-08 19:58:47 +000095 if (cmd == 8) {
96 n = klogctl(cmd, NULL, level);
97 if (n < 0) {
98 goto klogctl_error;
99 }
100 exit(TRUE);
101 }
Eric Andersen3cf52d11999-10-12 22:26:06 +0000102
Erik Andersene49d5ec2000-02-08 19:58:47 +0000103 if (bufsize < 4096)
104 bufsize = 4096;
Erik Andersen0d068a22000-03-21 22:32:57 +0000105 buf = (char *) xmalloc(bufsize);
Erik Andersene49d5ec2000-02-08 19:58:47 +0000106 n = klogctl(cmd, buf, bufsize);
107 if (n < 0) {
108 goto klogctl_error;
109 }
110
111 lastc = '\n';
112 for (i = 0; i < n; i++) {
113 if ((i == 0 || buf[i - 1] == '\n') && buf[i] == '<') {
114 i++;
115 while (buf[i] >= '0' && buf[i] <= '9')
116 i++;
117 if (buf[i] == '>')
118 i++;
119 }
120 lastc = buf[i];
121 putchar(lastc);
122 }
123 if (lastc != '\n')
124 putchar('\n');
125 exit(TRUE);
126 end:
127 usage(dmesg_usage);
128 exit(FALSE);
129 klogctl_error:
130 perror("klogctl");
Eric Andersenb6106152000-06-19 17:25:40 +0000131 return(FALSE);
Eric Andersencc8ed391999-10-05 16:24:54 +0000132}