* Licensed under GPLv2 or later, see file LICENSE in this source tree.
*/
+//usage:#define klogd_trivial_usage
+//usage: "[-c N] [-n]"
+//usage:#define klogd_full_usage "\n\n"
+//usage: "Kernel logger\n"
+//usage: "\n -c N Print to console messages more urgent than prio N (1-8)"
+//usage: "\n -n Run in foreground"
+
#include "libbb.h"
#include <syslog.h>
*/
klogd_open();
openlog("kernel", 0, LOG_KERN);
+ /*
+ * glibc problem: for some reason, glibc changes LOG_KERN to LOG_USER
+ * above. The logic behind this is that standard
+ * http://pubs.opengroup.org/onlinepubs/9699919799/functions/syslog.html
+ * says the following about openlog and syslog:
+ * "LOG_USER
+ * Messages generated by arbitrary processes.
+ * This is the default facility identifier if none is specified."
+ *
+ * I believe glibc misinterpreted this text as "if openlog's
+ * third parameter is 0 (=LOG_KERN), treat it as LOG_USER".
+ * Whereas it was meant to say "if *syslog* is called with facility
+ * 0 in its 1st parameter without prior call to openlog, then perform
+ * implicit openlog(LOG_USER)".
+ *
+ * As a result of this, eh, feature, standard klogd was forced
+ * to open-code its own openlog and syslog implementation (!).
+ *
+ * Note that prohibiting openlog(LOG_KERN) on libc level does not
+ * add any security: any process can open a socket to "/dev/log"
+ * and write a string "<0>Voila, a LOG_KERN + LOG_EMERG message"
+ *
+ * Google code search tells me there is no widespread use of
+ * openlog("foo", 0, 0), thus fixing glibc won't break userspace.
+ *
+ * The bug against glibc was filed:
+ * bugzilla.redhat.com/show_bug.cgi?id=547000
+ */
if (i)
klogd_setloglevel(i);
- bb_signals(BB_FATAL_SIGS, record_signo);
signal(SIGHUP, SIG_IGN);
+ /* We want klogd_read to not be restarted, thus _norestart: */
+ bb_signals_recursive_norestart(BB_FATAL_SIGS, record_signo);
syslog(LOG_NOTICE, "klogd started: %s", bb_banner);
+ write_pidfile(CONFIG_PID_FILE_PATH "/klogd.pid");
+
used = 0;
while (!bb_got_signal) {
int n;
priority = LOG_INFO;
if (*start == '<') {
start++;
- if (*start) {
- /* kernel never generates multi-digit prios */
- priority = (*start - '0');
- start++;
- }
+ if (*start)
+ priority = strtoul(start, &start, 10);
if (*start == '>')
start++;
}
klogd_close();
syslog(LOG_NOTICE, "klogd: exiting");
+ remove_pidfile(CONFIG_PID_FILE_PATH "/klogd.pid");
if (bb_got_signal)
kill_myself_with_sig(bb_got_signal);
return EXIT_FAILURE;