release/src/router/busybox/sysklogd/klogd.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini klogd implementation for busybox
   4  *
   5  * Copyright (C) 2001 by Gennady Feldman <gfeldman@gena01.com>.
   6  * Changes: Made this a standalone busybox module which uses standalone
   7  *                                      syslog() client interface.
   8  *
   9  * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
  10  *
  11  * Copyright (C) 2000 by Karl M. Hegbloom <karlheg@debian.org>
  12  *
  13  * "circular buffer" Copyright (C) 2000 by Gennady Feldman <gfeldman@gena01.com>
  14  *
  15  * Maintainer: Gennady Feldman <gfeldman@gena01.com> as of Mar 12, 2001
  16  *
  17  * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
  18  */
  19
  20 #include "libbb.h"
  21 #include <syslog.h>
  22 #include <sys/klog.h>
  23
  24 static void klogd_signal(int sig)
  25 {
  26         /* FYI: cmd 7 is equivalent to setting console_loglevel to 7
  27          * via klogctl(8, NULL, 7). */
  28         klogctl(7, NULL, 0); /* "7 -- Enable printk's to console" */
  29         klogctl(0, NULL, 0); /* "0 -- Close the log. Currently a NOP" */
  30         syslog(LOG_NOTICE, "klogd: exiting");
  31         kill_myself_with_sig(sig);
  32 }
  33
  34 #define log_buffer bb_common_bufsiz1
  35 enum {
  36         KLOGD_LOGBUF_SIZE = sizeof(log_buffer),
  37         OPT_LEVEL      = (1 << 0),
  38         OPT_FOREGROUND = (1 << 1),
  39 };
  40
  41 int klogd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  42 int klogd_main(int argc UNUSED_PARAM, char **argv)
  43 {
  44         int i = 0;
  45         char *opt_c;
  46         int opt;
  47         int used = 0;
  48
  49         opt = getopt32(argv, "c:n", &opt_c);
  50         if (opt & OPT_LEVEL) {
  51                 /* Valid levels are between 1 and 8 */
  52                 i = xatou_range(opt_c, 1, 8);
  53         }
  54         if (!(opt & OPT_FOREGROUND)) {
  55                 bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
  56         }
  57
  58         openlog("kernel", 0, LOG_KERN);
  59
  60         bb_signals(BB_FATAL_SIGS, klogd_signal);
  61         signal(SIGHUP, SIG_IGN);
  62
  63         /* "Open the log. Currently a NOP" */
  64         klogctl(1, NULL, 0);
  65
  66         /* "printk() prints a message on the console only if it has a loglevel
  67          * less than console_loglevel". Here we set console_loglevel = i. */
  68         if (i)
  69                 klogctl(8, NULL, i);
  70
  71         syslog(LOG_NOTICE, "klogd started: %s", bb_banner);
  72
  73         while (1) {
  74                 int n;
  75                 int priority;
  76                 char *start;
  77
  78                 /* "2 -- Read from the log." */
  79                 start = log_buffer + used;
  80                 n = klogctl(2, start, KLOGD_LOGBUF_SIZE-1 - used);
  81                 if (n < 0) {
  82                         if (errno == EINTR)
  83                                 continue;
  84                         syslog(LOG_ERR, "klogd: error %d in klogctl(2): %m",
  85                                         errno);
  86                         break;
  87                 }
  88                 start[n] = '\0';
  89
  90                 /* klogctl buffer parsing modelled after code in dmesg.c */
  91                 /* Process each newline-terminated line in the buffer */
  92                 start = log_buffer;
  93                 while (1) {
  94                         char *newline = strchrnul(start, '\n');
  95
  96                         if (*newline == '\0') {
  97                                 /* This line is incomplete... */
  98                                 if (start != log_buffer) {
  99                                         /* move it to the front of the buffer */
 100                                         overlapping_strcpy(log_buffer, start);
 101                                         used = newline - start;
 102                                         /* don't log it yet */
 103                                         break;
 104                                 }
 105                                 /* ...but if buffer is full, log it anyway */
 106                                 used = 0;
 107                                 newline = NULL;
 108                         } else {
 109                                 *newline++ = '\0';
 110                         }
 111
 112                         /* Extract the priority */
 113                         priority = LOG_INFO;
 114                         if (*start == '<') {
 115                                 start++;
 116                                 if (*start) {
 117                                         /* kernel never generates multi-digit prios */
 118                                         priority = (*start - '0');
 119                                         start++;
 120                                 }
 121                                 if (*start == '>')
 122                                         start++;
 123                         }
 124                         /* Log (only non-empty lines) */
 125                         if (*start)
 126                                 syslog(priority, "%s", start);
 127
 128                         if (!newline)
 129                                 break;
 130                         start = newline;
 131                 }
 132         }
 133
 134         return EXIT_FAILURE;
 135 }