dmesg.c

   1 /* vi: set sw=4 ts=4: */
   2 /* dmesg.c -- Print out the contents of the kernel ring buffer
   3  * Created: Sat Oct  9 16:19:47 1993
   4  * Revised: Thu Oct 28 21:52:17 1993 by faith@cs.unc.edu
   5  * Copyright 1993 Theodore Ts'o (tytso@athena.mit.edu)
   6  * This program comes with ABSOLUTELY NO WARRANTY.
   7  * Modifications by Rick Sladkey (jrs@world.std.com)
   8  * Larger buffersize 3 June 1998 by Nicolai Langfeldt, based on a patch
   9  * by Peeter Joot.  This was also suggested by John Hudson.
  10  * 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@misiek.eu.org>
  11  * - added Native Language Support
  12  *
  13  * from util-linux -- adapted for busybox by
  14  * Erik Andersen <andersee@debian.org>. I ripped out Native Language
  15  * Support, replaced getopt, added some gotos for redundant stuff.
  16  */
  17
  18 #include "internal.h"
  19 #include <linux/unistd.h>
  20 #include <stdio.h>
  21 #include <getopt.h>
  22 #include <stdlib.h>
  23
  24 #if __GNU_LIBRARY__ < 5
  25
  26 #ifndef __alpha__
  27 # define __NR_klogctl __NR_syslog
  28 static inline _syscall3(int, klogctl, int, type, char *, b, int, len);
  29 #else                                                   /* __alpha__ */
  30 #define klogctl syslog
  31 #endif
  32
  33 #else
  34 # include <sys/klog.h>
  35 #endif
  36
  37 static const char dmesg_usage[] = "dmesg [-c] [-n level] [-s bufsize]\n";
  38
  39 int dmesg_main(int argc, char **argv)
  40 {
  41         char *buf;
  42         int bufsize = 8196;
  43         int i;
  44         int n;
  45         int level = 0;
  46         int lastc;
  47         int cmd = 3;
  48         int stopDoingThat;
  49
  50         argc--;
  51         argv++;
  52
  53         /* Parse any options */
  54         while (argc && **argv == '-') {
  55                 stopDoingThat = FALSE;
  56                 while (stopDoingThat == FALSE && *++(*argv)) {
  57                         switch (**argv) {
  58                         case 'c':
  59                                 cmd = 4;
  60                                 break;
  61                         case 'n':
  62                                 cmd = 8;
  63                                 if (--argc == 0)
  64                                         goto end;
  65                                 level = atoi(*(++argv));
  66                                 if (--argc > 0)
  67                                         ++argv;
  68                                 stopDoingThat = TRUE;
  69                                 break;
  70                         case 's':
  71                                 if (--argc == 0)
  72                                         goto end;
  73                                 bufsize = atoi(*(++argv));
  74                                 if (--argc > 0)
  75                                         ++argv;
  76                                 stopDoingThat = TRUE;
  77                                 break;
  78                         default:
  79                                 goto end;
  80                         }
  81                 }
  82         }
  83
  84         if (argc > 1) {
  85                 goto end;
  86         }
  87
  88         if (cmd == 8) {
  89                 n = klogctl(cmd, NULL, level);
  90                 if (n < 0) {
  91                         goto klogctl_error;
  92                 }
  93                 exit(TRUE);
  94         }
  95
  96         if (bufsize < 4096)
  97                 bufsize = 4096;
  98         buf = (char *) xmalloc(bufsize);
  99         n = klogctl(cmd, buf, bufsize);
 100         if (n < 0) {
 101                 goto klogctl_error;
 102         }
 103
 104         lastc = '\n';
 105         for (i = 0; i < n; i++) {
 106                 if ((i == 0 || buf[i - 1] == '\n') && buf[i] == '<') {
 107                         i++;
 108                         while (buf[i] >= '0' && buf[i] <= '9')
 109                                 i++;
 110                         if (buf[i] == '>')
 111                                 i++;
 112                 }
 113                 lastc = buf[i];
 114                 putchar(lastc);
 115         }
 116         if (lastc != '\n')
 117                 putchar('\n');
 118         exit(TRUE);
 119   end:
 120         usage(dmesg_usage);
 121         exit(FALSE);
 122   klogctl_error:
 123         perror("klogctl");
 124         exit(FALSE);
 125
 126 }