release/src/router/busybox/util-linux/dmesg.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  *
   4  * dmesg - display/control kernel ring buffer.
   5  *
   6  * Copyright 2006 Rob Landley <rob@landley.net>
   7  * Copyright 2006 Bernhard Reutner-Fischer <rep.nop@aon.at>
   8  *
   9  * Licensed under GPLv2, see file LICENSE in this source tree.
  10  */
  11 #include <sys/klog.h>
  12 #include "libbb.h"
  13
  14 int dmesg_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  15 int dmesg_main(int argc UNUSED_PARAM, char **argv)
  16 {
  17         int len, level;
  18         char *buf;
  19         unsigned opts;
  20         enum {
  21                 OPT_c = 1 << 0,
  22                 OPT_s = 1 << 1,
  23                 OPT_n = 1 << 2
  24         };
  25
  26         opt_complementary = "s+:n+"; /* numeric */
  27         opts = getopt32(argv, "cs:n:", &len, &level);
  28         if (opts & OPT_n) {
  29                 if (klogctl(8, NULL, (long) level))
  30                         bb_perror_msg_and_die("klogctl");
  31                 return EXIT_SUCCESS;
  32         }
  33
  34         if (!(opts & OPT_s))
  35                 len = klogctl(10, NULL, 0); /* read ring buffer size */
  36         if (len < 16*1024)
  37                 len = 16*1024;
  38         if (len > 16*1024*1024)
  39                 len = 16*1024*1024;
  40
  41         buf = xmalloc(len);
  42         len = klogctl(3 + (opts & OPT_c), buf, len); /* read ring buffer */
  43         if (len < 0)
  44                 bb_perror_msg_and_die("klogctl");
  45         if (len == 0)
  46                 return EXIT_SUCCESS;
  47
  48
  49         if (ENABLE_FEATURE_DMESG_PRETTY) {
  50                 int last = '\n';
  51                 int in = 0;
  52
  53                 /* Skip <#> at the start of lines */
  54                 while (1) {
  55                         if (last == '\n' && buf[in] == '<') {
  56                                 in += 3;
  57                                 if (in >= len)
  58                                         break;
  59                         }
  60                         last = buf[in];
  61                         putchar(last);
  62                         in++;
  63                         if (in >= len)
  64                                 break;
  65                 }
  66                 /* Make sure we end with a newline */
  67                 if (last != '\n')
  68                         bb_putchar('\n');
  69         } else {
  70                 full_write(STDOUT_FILENO, buf, len);
  71                 if (buf[len-1] != '\n')
  72                         bb_putchar('\n');
  73         }
  74
  75         if (ENABLE_FEATURE_CLEAN_UP) free(buf);
  76
  77         return EXIT_SUCCESS;
  78 }