LXR 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
  24static 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
  35enum {
  36        KLOGD_LOGBUF_SIZE = sizeof(log_buffer),
  37        OPT_LEVEL      = (1 << 0),
  38        OPT_FOREGROUND = (1 << 1),
  39};
  40
  41int klogd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  42int 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}
 136