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/* vi: set sw=4 ts=4: */
/*
*
* dmesg - display/control kernel ring buffer.
*
* 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 (3.7 kb)"
//config: default y
//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)
//applet:IF_DMESG(APPLET(dmesg, BB_DIR_BIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_DMESG) += dmesg.o
//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) MAIN_EXTERNALLY_VISIBLE;
int dmesg_main(int argc UNUSED_PARAM, char **argv)
{
int len, level;
char *buf;
unsigned opts;
enum {
OPT_c = 1 << 0,
OPT_s = 1 << 1,
OPT_n = 1 << 2,
OPT_r = 1 << 3
};
opts = getopt32(argv, "cs:+n:+r", &len, &level);
if (opts & OPT_n) {
if (klogctl(8, NULL, (long) level))
bb_simple_perror_msg_and_die("klogctl");
return EXIT_SUCCESS;
}
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_simple_perror_msg_and_die("klogctl");
if (len == 0)
return EXIT_SUCCESS;
if (ENABLE_FEATURE_DMESG_PRETTY && !(opts & OPT_r)) {
int last = '\n';
int in = 0;
/* 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;
}
/* 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;
}
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