text: /* 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"
  //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 dmesg 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_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_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;
  }
  