8b6b472f4
Denys Vlasenko
2011-03-07
Subject
klogd: fix the problem of delayed handling of ^C and SIGTERM
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sysklogd/klogd.c+30 -1
| @@ -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); | |