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klogd: fix the problem of delayed handling of ^C and SIGTERM

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Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2011-03-07 10:57:26 +01:00
parent e6bb8d339f
commit 8b6b472f4e
1 changed files with 30 additions and 1 deletions
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31
sysklogd/klogd.c
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@ -150,12 +150,41 @@ int klogd_main(int argc UNUSED_PARAM, char **argv)
*/
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);