build system: -fno-builtin-printf

[oweals/busybox.git] / sysklogd / klogd.c

diff --git a/sysklogd/klogd.c b/sysklogd/klogd.c
index 3468656cc19c5347d0e5af69fb48e8b26d82633c..432ded1530be3054bf1f3ee9130d025a803833ee 100644 (file)
--- a/sysklogd/klogd.c
+++ b/sysklogd/klogd.c
@@ -14,9 +14,16 @@
  *
  * 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.
+ * 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>
 
@@ -132,7 +139,7 @@ int klogd_main(int argc UNUSED_PARAM, char **argv)
        int i = 0;
        char *opt_c;
        int opt;
-       int used = 0;
+       int used;
 
        opt = getopt32(argv, "c:n", &opt_c);
        if (opt & OPT_LEVEL) {
@@ -150,15 +157,47 @@ 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);
 
+       write_pidfile(CONFIG_PID_FILE_PATH "/klogd.pid");
+
+       used = 0;
        while (!bb_got_signal) {
                int n;
                int priority;
@@ -175,22 +214,22 @@ int klogd_main(int argc UNUSED_PARAM, char **argv)
                }
                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 */
+                               /* This line is incomplete */
+
+                               /* move it to the front of the buffer */
+                               overlapping_strcpy(log_buffer, start);
+                               used = newline - start;
+                               if (used < KLOGD_LOGBUF_SIZE-1) {
+                                       /* buffer isn't full */
                                        break;
                                }
-                               /* ...but if buffer is full, log it anyway */
+                               /* buffer is full, log it anyway */
                                used = 0;
                                newline = NULL;
                        } else {
@@ -201,11 +240,8 @@ int klogd_main(int argc UNUSED_PARAM, char **argv)
                        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++;
                        }
@@ -221,6 +257,7 @@ int klogd_main(int argc UNUSED_PARAM, char **argv)
 
        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;