Added automatic reopen of underlying device in case of libsml read 0. (…

…#370)

* Added automatic reopen of underlying device in case of libsml read 0.

As a workaround for #362 added an automatic reopen if
sml_transport_read returns 0 bytes.
Issue: #362

* Fix GTEST_LIBS_DIR for gmock.

Don't really know why this has changed. Might be that
gmock changed it.

* Added reopen as well to read to prevent use of invalid fd.

If reopen fails the fd might be invalid and the next read call
does a write or pass an invalid fd to sml_transport_read.
Now reopen gets triggered again and if it fails a sleep of 1s
is done to prevent busy loopings.

gmock/CMakeLists.txt

@@ -19,6 +19,6 @@ set(GTEST_INCLUDE_DIRS ${source_dir}/googletest/include PARENT_SCOPE)
 
 # Specify MainTest's link libraries
 ExternalProject_Get_Property(googlemock binary_dir)
-set(GTEST_LIBS_DIR ${binary_dir}/googlemock/gtest PARENT_SCOPE)
-set(GMOCK_LIBS_DIR ${binary_dir}/googlemock PARENT_SCOPE)
+set(GTEST_LIBS_DIR ${binary_dir}/lib PARENT_SCOPE)
+set(GMOCK_LIBS_DIR ${binary_dir}/lib PARENT_SCOPE)
 

include/protocols/MeterSML.hpp

@@ -8,7 +8,7 @@
  * @author Steffen Vogel <info@steffenvogel.de>
  * @author Juri Glass
  * @author Mathias Runge
- * @author Nadim El Sayed 
+ * @author Nadim El Sayed
  */
 /*
  * This file is part of volkzaehler.org
@@ -26,7 +26,7 @@
  * You should have received a copy of the GNU General Public License
  * along with volkszaehler.org. If not, see <http://www.gnu.org/licenses/>.
  */
- 
+
 #ifndef _SML_H_
 #define _SML_H_
 
@@ -54,20 +54,26 @@ class MeterSML : public vz::protocol::Protocol {
 
 	const char *host() const { return _host.c_str(); }
 	const char *device() const { return _device.c_str(); }
-  
+
 protected:
 	std::string _host;
 	std::string _device;
 	speed_t _baudrate;
 	parity_type_t _parity;
 	std::string _pull;
 	bool _use_local_time;
-	
+
 	int _fd;	/* file descriptor of port */
 	struct termios _old_tio;	/* required to reset port */
 
 	const int BUFFER_LEN;
 
+	/**
+	 * @brief reopen the underlying device. We do this to workaround issue #362
+	 * @return true if reopen was successful. False otherwise.
+	 * */
+	bool reopen();
+
 	/**
 	 * Parses SML list entry and stores it in reading pointed by rd
 	 *

src/protocols/MeterSML.cpp

@@ -166,6 +166,7 @@ MeterSML::MeterSML(std::list<Option> options)
 
 MeterSML::MeterSML(const MeterSML &proto)
 		: Protocol(proto)
+		,_fd(ERR)
 		, BUFFER_LEN(SML_BUFFER_LEN)
 {
 }
@@ -182,7 +183,10 @@ int MeterSML::open() {
 		char *addr = strdup(host());
 		const char *node = strsep(&addr, ":");
 		const char *service = strsep(&addr, ":");
-		if (node == NULL && service == NULL) return -1;
+		if (node == NULL && service == NULL) {
+			free(addr);
+			return -1;
+		}
 		_fd = _openSocket(node, service);
 		free(addr);
 	}
@@ -199,6 +203,16 @@ int MeterSML::close() {
 	return ::close(_fd);
 }
 
+bool MeterSML::reopen() {
+	print(log_warning, "reopen called. current fd=%d", name().c_str(), _fd);
+	if (_fd != ERR) {
+		(void)close(); // we ignore errors on close
+	}
+	(void)open();
+	print(log_info, "after reopen fd=%d", name().c_str(), _fd);
+	return _fd != ERR;
+}
+
 ssize_t MeterSML::read(std::vector<Reading> &rds, size_t n) {
 
 	unsigned char buffer[SML_BUFFER_LEN];
@@ -208,6 +222,14 @@ ssize_t MeterSML::read(std::vector<Reading> &rds, size_t n) {
 	sml_get_list_response *body;
 	sml_list *entry;
 
+	if (_fd < 0) {
+		if (!reopen()) {
+			// sleep a little bit to prevent busy looping
+			sleep(1);
+			return 0;
+		}
+	}
+
 	if (_pull.size()) {
 		int wlen = write(_fd,_pull.c_str(),_pull.size());
 		print(log_debug,"sending pullsequenz send (len:%d is:%d).", name().c_str(), _pull.size(), wlen);
@@ -216,6 +238,14 @@ ssize_t MeterSML::read(std::vector<Reading> &rds, size_t n) {
 	/* wait until we receive a new datagram from the meter (blocking read) */
 	bytes = sml_transport_read(_fd, buffer, SML_BUFFER_LEN);
 
+	if (0 == bytes) {
+		// try to reopen. see issue #362
+		if (reopen()) {
+			bytes = sml_transport_read(_fd, buffer, SML_BUFFER_LEN);
+			print(log_info, "sml_transport_read returned len=%d after reopen", name().c_str(), bytes);
+		}
+	}
+
 	if (bytes < 16) {
 		print(log_error, "short message from sml_transport_read len=%d", name().c_str(), bytes);
 		return(0);