/* 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 <andersen@codepoet.org>. I ripped out Native Language
- * Support, replaced getopt, added some gotos for redundant stuff.
+ * dmesg - display/control kernel ring buffer.
*
- * Audited and cleaned up on 7 March 2003 to reduce size of
- * check error handling by Erik Andersen <andersen@codepoet.org>
+ * Copyright 2006 Rob Landley <rob@landley.net>
+ * Copyright 2006 Bernhard Reutner-Fischer <rep.nop@aon.at>
+ *
+ * Licensed under GPLv2, see file LICENSE in this source tree.
*/
+//config:config DMESG
+//config: bool "dmesg"
+//config: default y
+//config: select PLATFORM_LINUX
+//config: help
+//config: dmesg is used to examine or control the kernel ring buffer. When the
+//config: Linux kernel prints messages to the system log, they are stored in
+//config: the kernel ring buffer. You can use dmesg to print the kernel's ring
+//config: buffer, clear the kernel ring buffer, change the size of the kernel
+//config: ring buffer, and change the priority level at which kernel messages
+//config: are also logged to the system console. Enable this option if you
+//config: wish to enable the 'dmesg' utility.
+//config:
+//config:config FEATURE_DMESG_PRETTY
+//config: bool "Pretty output"
+//config: default y
+//config: depends on DMESG
+//config: help
+//config: If you wish to scrub the syslog level from the output, say 'Y' here.
+//config: The syslog level is a string prefixed to every line with the form
+//config: "<#>".
+//config:
+//config: With this option you will see:
+//config: # dmesg
+//config: Linux version 2.6.17.4 .....
+//config: BIOS-provided physical RAM map:
+//config: BIOS-e820: 0000000000000000 - 000000000009f000 (usable)
+//config:
+//config: Without this option you will see:
+//config: # dmesg
+//config: <5>Linux version 2.6.17.4 .....
+//config: <6>BIOS-provided physical RAM map:
+//config: <6> BIOS-e820: 0000000000000000 - 000000000009f000 (usable)
-#include <stdio.h>
-#include <stdlib.h>
-#include <errno.h>
-#include <sys/klog.h>
+//applet:IF_DMESG(APPLET(dmesg, BB_DIR_BIN, BB_SUID_DROP))
+
+//kbuild:lib-$(CONFIG_DMESG) += dmesg.o
-#include "busybox.h"
+//usage:#define dmesg_trivial_usage
+//usage: "[-c] [-n LEVEL] [-s SIZE]"
+//usage:#define dmesg_full_usage "\n\n"
+//usage: "Print or control the kernel ring buffer\n"
+//usage: "\n -c Clear ring buffer after printing"
+//usage: "\n -n LEVEL Set console logging level"
+//usage: "\n -s SIZE Buffer size"
+//usage: "\n -r Print raw message buffer"
+
+#include <sys/klog.h>
+#include "libbb.h"
-int dmesg_main(int argc, char **argv)
+int dmesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int dmesg_main(int argc UNUSED_PARAM, char **argv)
{
- char *buf, *tmp;
- int bufsize = 8196;
- int i, n = 0;
- int c = 3;
+ int len, level;
+ char *buf;
+ unsigned opts;
+ enum {
+ OPT_c = 1 << 0,
+ OPT_s = 1 << 1,
+ OPT_n = 1 << 2,
+ OPT_r = 1 << 3
+ };
- i = bb_getopt_ulflags(argc, argv, "cn:s:", &buf, &tmp);
- if (i & 1)
- c = 4;
- if (i & 2) {
- c = 8;
- n = bb_xgetlarg(buf, 10, 0, 10);
+ opts = getopt32(argv, "cs:+n:+r", &len, &level);
+ if (opts & OPT_n) {
+ if (klogctl(8, NULL, (long) level))
+ bb_perror_msg_and_die("klogctl");
+ return EXIT_SUCCESS;
}
- if (i & 4)
- /* I think a 512k max kernel ring buffer is big enough for
- * anybody, as the default is 16k... Could be wrong though.
- * If so I'm sure I'll hear about it by the enraged masses*/
- bufsize = bb_xgetlarg(tmp, 10, 4096, 512*1024);
- if (c == 8) {
- if (klogctl(c, NULL, n) < 0)
- goto die_the_death;
- goto all_done;
- }
+ if (!(opts & OPT_s))
+ len = klogctl(10, NULL, 0); /* read ring buffer size */
+ if (len < 16*1024)
+ len = 16*1024;
+ if (len > 16*1024*1024)
+ len = 16*1024*1024;
+
+ buf = xmalloc(len);
+ len = klogctl(3 + (opts & OPT_c), buf, len); /* read ring buffer */
+ if (len < 0)
+ bb_perror_msg_and_die("klogctl");
+ if (len == 0)
+ return EXIT_SUCCESS;
+
- buf = xmalloc(bufsize);
- if ((n = klogctl(c, buf, bufsize)) < 0)
- goto die_the_death;
+ if (ENABLE_FEATURE_DMESG_PRETTY && !(opts & OPT_r)) {
+ int last = '\n';
+ int in = 0;
- c = '\n';
- for (i = 0; i < n; i++) {
- if (c == '\n' && buf[i] == '<') {
- i++;
- while (buf[i] >= '0' && buf[i] <= '9')
- i++;
- if (buf[i] == '>')
- i++;
+ /* Skip <[0-9]+> at the start of lines */
+ while (1) {
+ if (last == '\n' && buf[in] == '<') {
+ while (buf[in++] != '>' && in < len)
+ ;
+ } else {
+ last = buf[in++];
+ putchar(last);
+ }
+ if (in >= len)
+ break;
}
- c = buf[i];
- putchar(c);
- }
- if (c != '\n')
- putchar('\n');
-all_done:
- if (ENABLE_FEATURE_CLEAN_UP) {
- free(buf);
+ /* Make sure we end with a newline */
+ if (last != '\n')
+ bb_putchar('\n');
+ } else {
+ full_write(STDOUT_FILENO, buf, len);
+ if (buf[len-1] != '\n')
+ bb_putchar('\n');
}
+ if (ENABLE_FEATURE_CLEAN_UP) free(buf);
+
return EXIT_SUCCESS;
-die_the_death:
- bb_perror_nomsg_and_die();
}
projects / oweals / busybox.git / blobdiff