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/* vi: set sw=4 ts=4: */
/*
* Mini klogd implementation for busybox
*
* Copyright (C) 2001 by Gennady Feldman <gfeldman@gena01.com>.
* Changes: Made this a standalone busybox module which uses standalone
* syslog() client interface.
*
* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
*
* Copyright (C) 2000 by Karl M. Hegbloom <karlheg@debian.org>
*
* "circular buffer" Copyright (C) 2000 by Gennady Feldman <gfeldman@gena01.com>
*
* Maintainer: Gennady Feldman <gfeldman@gena01.com> as of Mar 12, 2001
*
* Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
*/
#include "libbb.h"
#include <syslog.h>
/* The Linux-specific klogctl(3) interface does not rely on the filesystem and
* allows us to change the console loglevel. Alternatively, we read the
* messages from _PATH_KLOG. */
#if ENABLE_FEATURE_KLOGD_KLOGCTL
# include <sys/klog.h>
static void klogd_open(void)
{
/* "Open the log. Currently a NOP" */
klogctl(1, NULL, 0);
}
static void klogd_setloglevel(int lvl)
{
/* "printk() prints a message on the console only if it has a loglevel
* less than console_loglevel". Here we set console_loglevel = lvl. */
klogctl(8, NULL, lvl);
}
static int klogd_read(char *bufp, int len)
{
return klogctl(2, bufp, len);
}
# define READ_ERROR "klogctl(2) error"
static void klogd_close(void)
{
/* FYI: cmd 7 is equivalent to setting console_loglevel to 7
* via klogctl(8, NULL, 7). */
klogctl(7, NULL, 0); /* "7 -- Enable printk's to console" */
klogctl(0, NULL, 0); /* "0 -- Close the log. Currently a NOP" */
}
#else
# include <paths.h>
# ifndef _PATH_KLOG
# ifdef __GNU__
# define _PATH_KLOG "/dev/klog"
# else
# error "your system's _PATH_KLOG is unknown"
# endif
# endif
# define PATH_PRINTK "/proc/sys/kernel/printk"
enum { klogfd = 3 };
static void klogd_open(void)
{
int fd = xopen(_PATH_KLOG, O_RDONLY);
xmove_fd(fd, klogfd);
}
static void klogd_setloglevel(int lvl)
{
FILE *fp = fopen_or_warn(PATH_PRINTK, "w");
if (fp) {
/* This changes only first value:
* "messages with a higher priority than this
* [that is, with numerically lower value]
* will be printed to the console".
* The other three values in this pseudo-file aren't changed.
*/
fprintf(fp, "%u\n", lvl);
fclose(fp);
}
}
static int klogd_read(char *bufp, int len)
{
return read(klogfd, bufp, len);
}
# define READ_ERROR "read error"
static void klogd_close(void)
{
klogd_setloglevel(7);
if (ENABLE_FEATURE_CLEAN_UP)
close(klogfd);
}
#endif
#define log_buffer bb_common_bufsiz1
enum {
KLOGD_LOGBUF_SIZE = sizeof(log_buffer),
OPT_LEVEL = (1 << 0),
OPT_FOREGROUND = (1 << 1),
};
/* TODO: glibc openlog(LOG_KERN) reverts to LOG_USER instead,
* because that's how they interpret word "default"
* in the openlog() manpage:
* LOG_USER (default)
* generic user-level messages
* and the fact that LOG_KERN is a constant 0.
* glibc interprets it as "0 in openlog() call means 'use default'".
* I think it means "if openlog wasn't called before syslog() is called,
* use default".
* Convincing glibc maintainers otherwise is, as usual, nearly impossible.
* Should we open-code syslog() here to use correct facility?
*/
int klogd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int klogd_main(int argc UNUSED_PARAM, char **argv)
{
int i = 0;
char *opt_c;
int opt;
int used = 0;
opt = getopt32(argv, "c:n", &opt_c);
if (opt & OPT_LEVEL) {
/* Valid levels are between 1 and 8 */
i = xatou_range(opt_c, 1, 8);
}
if (!(opt & OPT_FOREGROUND)) {
bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
}
logmode = LOGMODE_SYSLOG;
/* klogd_open() before openlog(), since it might use fixed fd 3,
* and openlog() also may use the same fd 3 if we swap them:
*/
klogd_open();
openlog("kernel", 0, LOG_KERN);
if (i)
klogd_setloglevel(i);
bb_signals(BB_FATAL_SIGS, record_signo);
signal(SIGHUP, SIG_IGN);
syslog(LOG_NOTICE, "klogd started: %s", bb_banner);
while (!bb_got_signal) {
int n;
int priority;
char *start;
/* "2 -- Read from the log." */
start = log_buffer + used;
n = klogd_read(start, KLOGD_LOGBUF_SIZE-1 - used);
if (n < 0) {
if (errno == EINTR)
continue;
bb_perror_msg(READ_ERROR);
break;
}
start[n] = '\0';
/* klogctl buffer parsing modelled after code in dmesg.c */
/* Process each newline-terminated line in the buffer */
start = log_buffer;
while (1) {
char *newline = strchrnul(start, '\n');
if (*newline == '\0') {
/* This line is incomplete... */
if (start != log_buffer) {
/* move it to the front of the buffer */
overlapping_strcpy(log_buffer, start);
used = newline - start;
/* don't log it yet */
break;
}
/* ...but if buffer is full, log it anyway */
used = 0;
newline = NULL;
} else {
*newline++ = '\0';
}
/* Extract the priority */
priority = LOG_INFO;
if (*start == '<') {
start++;
if (*start) {
/* kernel never generates multi-digit prios */
priority = (*start - '0');
start++;
}
if (*start == '>')
start++;
}
/* Log (only non-empty lines) */
if (*start)
syslog(priority, "%s", start);
if (!newline)
break;
start = newline;
}
}
klogd_close();
syslog(LOG_NOTICE, "klogd: exiting");
if (bb_got_signal)
kill_myself_with_sig(bb_got_signal);
return EXIT_FAILURE;
}
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