Minor changes to SysFS "retain" option

dcdbpusher/sensors/sysfs/SysfsSensorGroup.cpp

@@ -85,9 +85,10 @@ void SysfsSensorGroup::read() {
 			LOG(error) << "Error opening file " << _path << ":" << strerror(errno);
 			return;
 		}
+	} else {
+		fseek(_file, 0, SEEK_SET);
 	}
 	
-	fseek(_file, 0, SEEK_SET);
 	size_t nelem = fread(buf, 1, 1024, _file);
 	reading.timestamp = getTimestamp();
 
@@ -133,4 +134,5 @@ void SysfsSensorGroup::read() {
 void SysfsSensorGroup::printGroupConfig(LOG_LEVEL ll, unsigned int leadingSpaces) {
 	std::string leading(leadingSpaces, ' ');
 	LOG_VAR(ll) << leading << "File path: " << _path;
+	LOG_VAR(ll) << leading << "Retain:    " << (_retain ? "true" : "false");
 }