klogd: make help text more understandable

klogd: by using a register instead of global variable, shrink code a bit

function                                             old     new   delta
klogd_main                                           372     362     -10
packed_usage                                       24504   24486     -18
   text    data     bss     dec     hex filename
 808464     642    7180  816286   c749e busybox_old
 808422     642    7180  816244   c7474 busybox_unstripped

2 files changed, 19 insertions, 18 deletions

diff --git a/include/usage.h b/include/usage.h
index f9a831e85..44e618222 100644
--- a/include/usage.h
+++ b/include/usage.h
@@ -2063,11 +2063,11 @@
      "\n        -l      List all signal names and numbers" \
 
 #define klogd_trivial_usage \
-       "[-c n] [-n]"
+       "[-c N] [-n]"
 #define klogd_full_usage "\n\n" \
        "Kernel logger\n" \
      "\nOptions:" \
-     "\n        -c n    Set the default log level of console messages to n" \
+     "\n        -c N    Only messages with level < N are printed to console" \
      "\n        -n      Run in foreground" \
 
 #define length_trivial_usage \
diff --git a/sysklogd/klogd.c b/sysklogd/klogd.c
index 983a59784..e719001cf 100644
--- a/sysklogd/klogd.c
+++ b/sysklogd/klogd.c
@@ -21,10 +21,12 @@
 #include <syslog.h>
 #include <sys/klog.h>
 
-static void klogd_signal(int sig ATTRIBUTE_UNUSED)
+static void klogd_signal(int sig)
 {
-        klogctl(7, NULL, 0);
-        klogctl(0, NULL, 0);
+        /* FYI: cmd 7 is equivalent to setting console_loglevel to 7
+         * via klogctl(8, NULL, 7). */
+        klogctl(7, NULL, 0); /* "7 -- Enable printk's to console" */
+        klogctl(0, NULL, 0); /* "0 -- Close the log. Currently a NOP" */
         syslog(LOG_NOTICE, "klogd: exiting");
         kill_myself_with_sig(sig);
 }
@@ -39,35 +41,33 @@ enum {
 int klogd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int klogd_main(int argc ATTRIBUTE_UNUSED, char **argv)
 {
-        int i = i; /* silence gcc */
+        int i = 0;
         char *start;
+        int opt;
 
-        /* do normal option parsing */
-        getopt32(argv, "c:n", &start);
-
-        if (option_mask32 & OPT_LEVEL) {
+        opt = getopt32(argv, "c:n", &start);
+        if (opt & OPT_LEVEL) {
                 /* Valid levels are between 1 and 8 */
-                i = xatoul_range(start, 1, 8);
+                i = xatou_range(start, 1, 8);
         }
-
-        if (!(option_mask32 & OPT_FOREGROUND)) {
+        if (!(opt & OPT_FOREGROUND)) {
                 bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
         }
 
         openlog("kernel", 0, LOG_KERN);
 
-        /* Set up sig handlers */
         bb_signals(0
                 + (1 << SIGINT)
                 + (1 << SIGTERM)
                 , klogd_signal);
         signal(SIGHUP, SIG_IGN);
 
-        /* "Open the log. Currently a NOP." */
+        /* "Open the log. Currently a NOP" */
         klogctl(1, NULL, 0);
 
-        /* Set level of kernel console messaging. */
-        if (option_mask32 & OPT_LEVEL)
+        /* "printk() prints a message on the console only if it has a loglevel
+         * less than console_loglevel". Here we set console_loglevel = i. */
+        if (i)
                 klogctl(8, NULL, i);
 
         syslog(LOG_NOTICE, "klogd started: %s", bb_banner);
@@ -80,11 +80,12 @@ int klogd_main(int argc ATTRIBUTE_UNUSED, char **argv)
                 int n;
                 int priority;
 
+                /* "2 -- Read from the log." */
                 n = klogctl(2, log_buffer, KLOGD_LOGBUF_SIZE - 1);
                 if (n < 0) {
                         if (errno == EINTR)
                                 continue;
-                        syslog(LOG_ERR, "klogd: error from klogctl(2): %d - %m",
+                        syslog(LOG_ERR, "klogd: error %d in klogctl(2): %m",
                                         errno);
                         break;
                 }