3 files changed, 93 insertions, 15 deletions

diff --git a/sysklogd/Config.src b/sysklogd/Config.src
index b7a494eff..fcf993054 100644
--- a/sysklogd/Config.src
+++ b/sysklogd/Config.src
@@ -113,6 +113,19 @@ config FEATURE_LOGREAD_REDUCED_LOCKING
           from circular buffer, minimizing semaphore
           contention at some minor memory expense.
 
+config FEATURE_KMSG_SYSLOG
+        bool "Linux kernel printk buffer support"
+        default y
+        depends on SYSLOGD
+        select PLATFORM_LINUX
+        help
+          When you enable this feature, the syslogd utility will
+          write system log message to the Linux kernel's printk buffer.
+          This can be used as a smaller alternative to the syslogd IPC
+          support, as klogd and logread aren't needed.
+
+          NOTICE: Syslog facilities in log entries needs kernel 3.5+.
+
 config KLOGD
         bool "klogd"
         default y
@@ -123,6 +136,9 @@ config KLOGD
           you wish to record the messages produced by the kernel,
           you should enable this option.
 
+comment "klogd should not be used together with syslog to kernel printk buffer"
+        depends on KLOGD && FEATURE_KMSG_SYSLOG
+
 config FEATURE_KLOGD_KLOGCTL
         bool "Use the klogctl() interface"
         default y
diff --git a/sysklogd/klogd.c b/sysklogd/klogd.c
index efa0e537a..432ded153 100644
--- a/sysklogd/klogd.c
+++ b/sysklogd/klogd.c
@@ -195,6 +195,8 @@ int klogd_main(int argc UNUSED_PARAM, char **argv)
 
         syslog(LOG_NOTICE, "klogd started: %s", bb_banner);
 
+        write_pidfile(CONFIG_PID_FILE_PATH "/klogd.pid");
+
         used = 0;
         while (!bb_got_signal) {
                 int n;
@@ -238,11 +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++;
                         }
@@ -258,6 +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;
diff --git a/sysklogd/syslogd.c b/sysklogd/syslogd.c
index fc380d9f9..3fe3f5348 100644
--- a/sysklogd/syslogd.c
+++ b/sysklogd/syslogd.c
@@ -43,6 +43,9 @@
 //usage:     "\n        -f FILE         Use FILE as config (default:/etc/syslog.conf)"
 //usage:        )
 /* //usage:  "\n        -m MIN          Minutes between MARK lines (default:20, 0=off)" */
+//usage:        IF_FEATURE_KMSG_SYSLOG(
+//usage:     "\n        -K              Log to kernel printk buffer (use dmesg to read it)"
+//usage:        )
 //usage:
 //usage:#define syslogd_example_usage
 //usage:       "$ syslogd -R masterlog:514\n"
@@ -140,6 +143,10 @@ IF_FEATURE_IPC_SYSLOG( \
 ) \
 IF_FEATURE_SYSLOGD_CFG( \
         logRule_t *log_rules; \
+) \
+IF_FEATURE_KMSG_SYSLOG( \
+        int kmsgfd; \
+        int primask; \
 )
 
 struct init_globals {
@@ -212,6 +219,7 @@ enum {
         IF_FEATURE_IPC_SYSLOG(    OPTBIT_circularlog,)  // -C
         IF_FEATURE_SYSLOGD_DUP(   OPTBIT_dup        ,)  // -D
         IF_FEATURE_SYSLOGD_CFG(   OPTBIT_cfg        ,)  // -f
+        IF_FEATURE_KMSG_SYSLOG(   OPTBIT_kmsg       ,)  // -K
 
         OPT_mark        = 1 << OPTBIT_mark    ,
         OPT_nofork      = 1 << OPTBIT_nofork  ,
@@ -225,6 +233,8 @@ enum {
         OPT_circularlog = IF_FEATURE_IPC_SYSLOG(    (1 << OPTBIT_circularlog)) + 0,
         OPT_dup         = IF_FEATURE_SYSLOGD_DUP(   (1 << OPTBIT_dup        )) + 0,
         OPT_cfg         = IF_FEATURE_SYSLOGD_CFG(   (1 << OPTBIT_cfg        )) + 0,
+        OPT_kmsg        = IF_FEATURE_KMSG_SYSLOG(   (1 << OPTBIT_kmsg       )) + 0,
+
 };
 #define OPTION_STR "m:nO:l:S" \
         IF_FEATURE_ROTATE_LOGFILE("s:" ) \
@@ -233,7 +243,8 @@ enum {
         IF_FEATURE_REMOTE_LOG(    "L"  ) \
         IF_FEATURE_IPC_SYSLOG(    "C::") \
         IF_FEATURE_SYSLOGD_DUP(   "D"  ) \
-        IF_FEATURE_SYSLOGD_CFG(   "f:"  )
+        IF_FEATURE_SYSLOGD_CFG(   "f:" ) \
+        IF_FEATURE_KMSG_SYSLOG(   "K"  )
 #define OPTION_DECL *opt_m, *opt_l \
         IF_FEATURE_ROTATE_LOGFILE(,*opt_s) \
         IF_FEATURE_ROTATE_LOGFILE(,*opt_b) \
@@ -242,7 +253,7 @@ enum {
 #define OPTION_PARAM &opt_m, &(G.logFile.path), &opt_l \
         IF_FEATURE_ROTATE_LOGFILE(,&opt_s) \
         IF_FEATURE_ROTATE_LOGFILE(,&opt_b) \
-        IF_FEATURE_REMOTE_LOG(    ,&remoteAddrList) \
+        IF_FEATURE_REMOTE_LOG(    ,&remoteAddrList) \
         IF_FEATURE_IPC_SYSLOG(    ,&opt_C) \
         IF_FEATURE_SYSLOGD_CFG(   ,&opt_f)
 
@@ -418,7 +429,9 @@ static void parse_syslogdcfg(const char *file)
         return;
 
  cfgerr:
-        bb_error_msg_and_die("error in '%s' at line %d", file, parser->lineno);
+        bb_error_msg_and_die("error in '%s' at line %d",
+                        file ? file : "/etc/syslog.conf",
+                        parser->lineno);
 }
 #endif
 
@@ -518,11 +531,49 @@ static void log_to_shmem(const char *msg)
                 printf("tail:%d\n", G.shbuf->tail);
 }
 #else
-void ipcsyslog_cleanup(void);
-void ipcsyslog_init(void);
+static void ipcsyslog_cleanup(void) {}
+static void ipcsyslog_init(void) {}
 void log_to_shmem(const char *msg);
 #endif /* FEATURE_IPC_SYSLOG */
 
+#if ENABLE_FEATURE_KMSG_SYSLOG
+static void kmsg_init(void)
+{
+        G.kmsgfd = xopen("/dev/kmsg", O_WRONLY);
+
+        /*
+         * kernel < 3.5 expects single char printk KERN_* priority prefix,
+         * from 3.5 onwards the full syslog facility/priority format is supported
+         */
+        if (get_linux_version_code() < KERNEL_VERSION(3,5,0))
+                G.primask = LOG_PRIMASK;
+        else
+                G.primask = -1;
+}
+
+static void kmsg_cleanup(void)
+{
+        if (ENABLE_FEATURE_CLEAN_UP)
+                close(G.kmsgfd);
+}
+
+/* Write message to /dev/kmsg */
+static void log_to_kmsg(int pri, const char *msg)
+{
+        /*
+         * kernel < 3.5 expects single char printk KERN_* priority prefix,
+         * from 3.5 onwards the full syslog facility/priority format is supported
+         */
+        pri &= G.primask;
+
+        write(G.kmsgfd, G.printbuf, sprintf(G.printbuf, "<%d>%s\n", pri, msg));
+}
+#else
+static void kmsg_init(void) {}
+static void kmsg_cleanup(void) {}
+static void log_to_kmsg(int pri UNUSED_PARAM, const char *msg UNUSED_PARAM) {}
+#endif /* FEATURE_KMSG_SYSLOG */
+
 /* Print a message to the log file. */
 static void log_locally(time_t now, char *msg, logFile_t *log_file)
 {
@@ -657,6 +708,11 @@ static void timestamp_and_log(int pri, char *msg, int len)
         }
         timestamp[15] = '\0';
 
+        if (option_mask32 & OPT_kmsg) {
+                log_to_kmsg(pri, msg);
+                return;
+        }
+
         if (option_mask32 & OPT_small)
                 sprintf(G.printbuf, "%s %s\n", timestamp, msg);
         else {
@@ -827,9 +883,11 @@ static void do_syslogd(void)
 #endif
         sock_fd = create_socket();
 
-        if (ENABLE_FEATURE_IPC_SYSLOG && (option_mask32 & OPT_circularlog)) {
+        if (option_mask32 & OPT_circularlog)
                 ipcsyslog_init();
-        }
+
+        if (option_mask32 & OPT_kmsg)
+                kmsg_init();
 
         timestamp_and_log_internal("syslogd started: BusyBox v" BB_VER);
 
@@ -916,8 +974,10 @@ static void do_syslogd(void)
 
         timestamp_and_log_internal("syslogd exiting");
         puts("syslogd exiting");
-        if (ENABLE_FEATURE_IPC_SYSLOG)
-                ipcsyslog_cleanup();
+        remove_pidfile(CONFIG_PID_FILE_PATH "/syslogd.pid");
+        ipcsyslog_cleanup();
+        if (option_mask32 & OPT_kmsg)
+                kmsg_cleanup();
         kill_myself_with_sig(bb_got_signal);
 #undef recvbuf
 }
@@ -979,8 +1039,10 @@ int syslogd_main(int argc UNUSED_PARAM, char **argv)
         if (!(opts & OPT_nofork)) {
                 bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
         }
+
         //umask(0); - why??
-        write_pidfile("/var/run/syslogd.pid");
+        write_pidfile(CONFIG_PID_FILE_PATH "/syslogd.pid");
+
         do_syslogd();
         /* return EXIT_SUCCESS; */
 }