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124 lines
3.4 KiB
C
124 lines
3.4 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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*
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* dmesg - display/control kernel ring buffer.
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*
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* Copyright 2006 Rob Landley <rob@landley.net>
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* Copyright 2006 Bernhard Reutner-Fischer <rep.nop@aon.at>
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*
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* Licensed under GPLv2, see file LICENSE in this source tree.
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*/
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//config:config DMESG
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//config: bool "dmesg (3.9 kb)"
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//config: default y
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//config: help
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//config: dmesg is used to examine or control the kernel ring buffer. When the
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//config: Linux kernel prints messages to the system log, they are stored in
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//config: the kernel ring buffer. You can use dmesg to print the kernel's ring
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//config: buffer, clear the kernel ring buffer, change the size of the kernel
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//config: ring buffer, and change the priority level at which kernel messages
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//config: are also logged to the system console. Enable this option if you
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//config: wish to enable the 'dmesg' utility.
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//config:
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//config:config FEATURE_DMESG_PRETTY
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//config: bool "Pretty output"
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//config: default y
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//config: depends on DMESG
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//config: help
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//config: If you wish to scrub the syslog level from the output, say 'Y' here.
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//config: The syslog level is a string prefixed to every line with the form
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//config: "<#>".
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//config:
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//config: With this option you will see:
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//config: # dmesg
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//config: Linux version 2.6.17.4 .....
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//config: BIOS-provided physical RAM map:
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//config: BIOS-e820: 0000000000000000 - 000000000009f000 (usable)
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//config:
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//config: Without this option you will see:
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//config: # dmesg
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//config: <5>Linux version 2.6.17.4 .....
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//config: <6>BIOS-provided physical RAM map:
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//config: <6> BIOS-e820: 0000000000000000 - 000000000009f000 (usable)
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//applet:IF_DMESG(APPLET(dmesg, BB_DIR_BIN, BB_SUID_DROP))
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//kbuild:lib-$(CONFIG_DMESG) += dmesg.o
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//usage:#define dmesg_trivial_usage
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//usage: "[-cr] [-n LEVEL] [-s SIZE]"
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//usage:#define dmesg_full_usage "\n\n"
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//usage: "Print or control the kernel ring buffer\n"
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//usage: "\n -c Clear ring buffer after printing"
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//usage: "\n -n LEVEL Set console logging level"
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//usage: "\n -s SIZE Buffer size"
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//usage: "\n -r Print raw message buffer"
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#include <sys/klog.h>
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#include "libbb.h"
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int dmesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int dmesg_main(int argc UNUSED_PARAM, char **argv)
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{
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int len, level;
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char *buf;
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unsigned opts;
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enum {
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OPT_c = 1 << 0,
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OPT_s = 1 << 1,
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OPT_n = 1 << 2,
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OPT_r = 1 << 3
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};
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opts = getopt32(argv, "cs:+n:+r", &len, &level);
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if (opts & OPT_n) {
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if (klogctl(8, NULL, (long) level))
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bb_simple_perror_msg_and_die("klogctl");
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return EXIT_SUCCESS;
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}
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if (!(opts & OPT_s))
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len = klogctl(10, NULL, 0); /* read ring buffer size */
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if (len < 16*1024)
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len = 16*1024;
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if (len > 16*1024*1024)
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len = 16*1024*1024;
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buf = xmalloc(len);
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len = klogctl(3 + (opts & OPT_c), buf, len); /* read ring buffer */
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if (len < 0)
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bb_simple_perror_msg_and_die("klogctl");
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if (len == 0)
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return EXIT_SUCCESS;
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if (ENABLE_FEATURE_DMESG_PRETTY && !(opts & OPT_r)) {
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int last = '\n';
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int in = 0;
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/* Skip <[0-9]+> at the start of lines */
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while (1) {
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if (last == '\n' && buf[in] == '<') {
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while (buf[in++] != '>' && in < len)
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;
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} else {
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last = buf[in++];
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putchar(last);
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}
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if (in >= len)
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break;
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}
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/* Make sure we end with a newline */
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if (last != '\n')
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bb_putchar('\n');
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} else {
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full_write(STDOUT_FILENO, buf, len);
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if (buf[len-1] != '\n')
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bb_putchar('\n');
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}
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if (ENABLE_FEATURE_CLEAN_UP) free(buf);
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return EXIT_SUCCESS;
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}
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