sensord: Reload config on SIGHUP rather than automatically.

Reloading the configuration on SIGHUP is common for daemons. Reloading
automatically is less efficient and can be confusing or even racy.


git-svn-id: http://lm-sensors.org/svn/lm-sensors/branches/lm-sensors-3.0.0@4969 7894878c-1315-0410-8ee3-d5d059ff63e0

CHANGES

@@ -2,6 +2,7 @@ lm-sensors CHANGES file
 -----------------------
 
 SVN HEAD
+  sensord: Reload config on SIGHUP rather than automatically
   sensors-detect: Fix SMSC LPC47B357/M967 detection
                   Select the right driver for FSC chips
 

prog/sensord/lib.c

@@ -31,8 +31,6 @@
 #include "sensord.h"
 #include "lib/error.h"
 
-static time_t cfgLastModified;
-
 static int
 loadConfig
 (const char *cfgPath, int reload) {
@@ -51,7 +49,7 @@ loadConfig
   } else if (stat (cfgPath, &stats) < 0) {
     sensorLog (LOG_ERR, "Error stating sensors configuration file: %s", cfgPath);
     ret = 10;
-  } else if (!reload || (difftime (stats.st_mtime, cfgLastModified) > 0.0)) {
+  } else {
     if (reload) {
       sensorLog (LOG_INFO, "configuration reloading");
       sensors_cleanup ();
@@ -63,8 +61,6 @@ loadConfig
       sensorLog (LOG_ERR, "Error loading sensors configuration file %s: %s",
                  cfgPath, sensors_strerror (ret));
       ret = 11;
-    } else {
-      cfgLastModified = stats.st_mtime;
     }
     if (cfg)
       fclose (cfg);

prog/sensord/sensord.8

@@ -133,6 +133,9 @@ modules for chips in which you have no interest.
 Upon receipt of a SIGTERM (see
 .BR signal (7)
 for details) this daemon should gracefully shut down.
+
+Upon receipt of a SIGHUP, this daemon will rescan the kernel interface
+for chips and features, and reload the libsensors configuration file.
 .SH LOGGING
 All messages from this daemon are logged to
 .BR syslog (3)

prog/sensord/sensord.c

@@ -37,6 +37,7 @@
 static int logOpened = 0;
 
 static volatile sig_atomic_t done = 0;
+static volatile sig_atomic_t reload = 0;
 
 #define LOG_BUFFER 4096
 
@@ -69,6 +70,9 @@ signalHandler
     case SIGTERM:
       done = 1;
       break;
+    case SIGHUP:
+      reload = 1;
+      break;
   }
 }
 
@@ -86,8 +90,10 @@ sensord
   sensorLog (LOG_INFO, "sensord started");
 
   while (!done && (ret == 0)) {
-    if (ret == 0)
+    if (reload) {
       ret = reloadLib (sensorsCfgFile);
+      reload = 0;
+    }
     if ((ret == 0) && scanTime) { /* should I scan on the read cycle? */
       ret = scanChips ();
       if (scanValue <= 0)
@@ -156,8 +162,9 @@ daemonize
   }
   
   /* I should use sigaction but... */
-  if (signal (SIGTERM, signalHandler) == SIG_ERR) {
-    perror ("signal(SIGTERM)");
+  if (signal (SIGTERM, signalHandler) == SIG_ERR ||
+      signal (SIGHUP, signalHandler) == SIG_ERR) {
+    perror ("signal");
     exit (EXIT_FAILURE);
   }