dmesg.c

/* 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 <andersee@debian.org>. I ripped out Native Language 
 * Support, replaced getopt, added some gotos for redundant stuff.
 */

#include "internal.h"
#include <linux/unistd.h>
#include <stdio.h>
#include <getopt.h>
#include <stdlib.h>

#if __GNU_LIBRARY__ < 5

#ifndef __alpha__
# define __NR_klogctl __NR_syslog
  static inline _syscall3(int, klogctl, int, type, char *, b, int, len);
#else /* __alpha__ */
#define klogctl syslog
#endif

#else
# include <sys/klog.h>
#endif

static const char dmesg_usage[] = "dmesg [-c] [-n level] [-s bufsize]\n";

int dmesg_main( int argc, char** argv )
{
   char *buf;
   int	bufsize=8196;
   int  i;
   int  n;
   int  level = 0;
   int  lastc;
   int  cmd = 3;
   int stopDoingThat;

   argc--;
   argv++;

    /* Parse any options */
    while (argc && **argv == '-') {
	stopDoingThat = FALSE;
	while (stopDoingThat == FALSE && *++(*argv)) {
	    switch (**argv) {
	    case 'c':
		cmd = 4;
		break;
	    case 'n':
		cmd = 8;
		if (--argc == 0)
		    goto end;
		level = atoi (*(++argv));
		if (--argc > 0)
		    ++argv;
		stopDoingThat = TRUE;
		break;
	    case 's':
		if (--argc == 0)
		    goto end;
		bufsize = atoi (*(++argv));
		if (--argc > 0)
		    ++argv;
		stopDoingThat = TRUE;
		break;
	    default:
		goto end;
	    }
	}
    }
   
   if (argc > 1) {
	goto end;
   }

   if (cmd == 8) {
      n = klogctl( cmd, NULL, level );
      if (n < 0) {
	  goto klogctl_error;
      }
      exit( TRUE );
   }

   if (bufsize < 4096) bufsize = 4096;
   buf = (char*)malloc(bufsize);
   n = klogctl( cmd, buf, bufsize );
   if (n < 0) {
       goto klogctl_error;
   }

   lastc = '\n';
   for (i = 0; i < n; i++) {
      if ((i == 0 || buf[i - 1] == '\n') && buf[i] == '<') {
	 i++;
	 while (buf[i] >= '0' && buf[i] <= '9')
	    i++;
	 if (buf[i] == '>')
	    i++;
      }
      lastc = buf[i];
      putchar( lastc );
   }
   if (lastc != '\n')
      putchar( '\n' );
   exit( TRUE);
end:
    usage( dmesg_usage);
    exit (FALSE);
klogctl_error:
    perror( "klogctl" );
    exit( FALSE );

}