Ensure port still exists when trying to gain elevated access

src/main/c/Posix/PosixHelperFunctions.c

@@ -1640,37 +1640,41 @@ int verifyAndSetUserPortGroup(const char *portFile)
 	// Attempt to acquire access if not available
 	if (!userCanAccess)
 	{
-		// Check if the user is part of the group that owns the port
+		// Ensure that the port still exists
 		struct stat fileStats;
-		gid_t *userGroups = (gid_t*)malloc(numGroups * sizeof(gid_t));
-		if ((stat(portFile, &fileStats) == 0) && (getgroups(numGroups, userGroups) >= 0))
-			for (int i = 0; i < numGroups; ++i)
-				if (userGroups[i] == fileStats.st_gid)
-				{
-					userPartOfPortGroup = 1;
-					break;
-				}
-
-		// Attempt to add the user to the group that owns the port
-		char *addUserToGroupCmd = (char*)malloc(256);
-		if (!userPartOfPortGroup)
+		if (stat(portFile, &fileStats) == 0)
 		{
-			struct group *portGroup;
-			struct passwd *userDetails;
-			if ((portGroup = getgrgid(fileStats.st_gid)) && (userDetails = getpwuid(geteuid())))
+			// Check if the user is part of the group that owns the port
+			gid_t *userGroups = (gid_t*)malloc(numGroups * sizeof(gid_t));
+			if (getgroups(numGroups, userGroups) >= 0)
+				for (int i = 0; i < numGroups; ++i)
+					if (userGroups[i] == fileStats.st_gid)
+					{
+						userPartOfPortGroup = 1;
+						break;
+					}
+
+			// Attempt to add the user to the group that owns the port
+			char *addUserToGroupCmd = (char*)malloc(256);
+			if (!userPartOfPortGroup)
 			{
-				snprintf(addUserToGroupCmd, 256, "sudo usermod -a -G %s %s", portGroup->gr_name, userDetails->pw_name);
-				userCanAccess = (system(addUserToGroupCmd) == 0);
+				struct group *portGroup;
+				struct passwd *userDetails;
+				if ((portGroup = getgrgid(fileStats.st_gid)) && (userDetails = getpwuid(geteuid())))
+				{
+					snprintf(addUserToGroupCmd, 256, "sudo usermod -a -G %s %s", portGroup->gr_name, userDetails->pw_name);
+					userCanAccess = (system(addUserToGroupCmd) == 0);
+				}
 			}
-		}
 
-		// Attempt to enable all read/write port permissions
-		snprintf(addUserToGroupCmd, 256, "sudo chmod 666 %s", portFile);
-		userCanAccess = (system(addUserToGroupCmd) == 0) || userCanAccess;
+			// Attempt to enable all read/write port permissions
+			snprintf(addUserToGroupCmd, 256, "sudo chmod 666 %s", portFile);
+			userCanAccess = (system(addUserToGroupCmd) == 0) || userCanAccess;
 
-		// Clean up memory
-		free(addUserToGroupCmd);
-		free(userGroups);
+			// Clean up memory
+			free(addUserToGroupCmd);
+			free(userGroups);
+		}
 	}
 
 	// Return whether the user can currently access the serial port

src/test/java/com/fazecast/jSerialComm/SerialPortTest.java

@@ -268,18 +268,22 @@ public void run()
 		ubxPort.addDataListener(new SerialPortDataListener() {
 			@Override
 			public int getListeningEvents() { return SerialPort.LISTENING_EVENT_PARITY_ERROR | SerialPort.LISTENING_EVENT_DATA_WRITTEN | SerialPort.LISTENING_EVENT_BREAK_INTERRUPT |
-					SerialPort.LISTENING_EVENT_CARRIER_DETECT | SerialPort.LISTENING_EVENT_CTS | SerialPort.LISTENING_EVENT_DSR | SerialPort.LISTENING_EVENT_RING_INDICATOR | 
+					SerialPort.LISTENING_EVENT_CARRIER_DETECT | SerialPort.LISTENING_EVENT_CTS | SerialPort.LISTENING_EVENT_DSR | SerialPort.LISTENING_EVENT_RING_INDICATOR | SerialPort.LISTENING_EVENT_PORT_DISCONNECTED |
 					SerialPort.LISTENING_EVENT_FRAMING_ERROR | SerialPort.LISTENING_EVENT_FIRMWARE_OVERRUN_ERROR | SerialPort.LISTENING_EVENT_SOFTWARE_OVERRUN_ERROR | SerialPort.LISTENING_EVENT_DATA_AVAILABLE; }
 			@Override
 			public void serialEvent(SerialPortEvent event)
 			{
-				System.out.println("Received event type: " + event.getEventType());
 				if (event.getEventType() == SerialPort.LISTENING_EVENT_DATA_AVAILABLE)
 				{
+					System.out.println("Received event type: LISTENING_EVENT_DATA_AVAILABLE");
 					byte[] buffer = new byte[event.getSerialPort().bytesAvailable()];
 					event.getSerialPort().readBytes(buffer, buffer.length);
 					System.out.println("   Reading " + buffer.length + " bytes");
 				}
+				else if (event.getEventType() == SerialPort.LISTENING_EVENT_PORT_DISCONNECTED)
+					System.out.println("Received event type: LISTENING_EVENT_PORT_DISCONNECTED");
+				else
+					System.out.println("Received event type: " + event.getEventType());
 			}
 		});
 		try { Thread.sleep(5000); } catch (Exception e) {}
@@ -311,29 +315,6 @@ public void serialEvent(SerialPortEvent event)
 		ubxPort.removeDataListener();
 		System.out.println("\nClosing " + ubxPort.getDescriptivePortName() + ": " + ubxPort.closePort());
 
-		/*System.out.println("\nPhysically unplug device within the next 10 seconds to see if the disconnect event fires...");
-		ubxPort.addDataListener(new SerialPortDataListener() {
-			@Override
-			public int getListeningEvents() { return SerialPort.LISTENING_EVENT_PORT_DISCONNECTED | SerialPort.LISTENING_EVENT_DATA_AVAILABLE; }
-			@Override
-			public void serialEvent(SerialPortEvent event)
-			{
-				if (event.getEventType() == SerialPort.LISTENING_EVENT_DATA_AVAILABLE)
-				{
-					System.out.println("Received event type: LISTENING_EVENT_DATA_AVAILABLE");
-					byte[] buffer = new byte[event.getSerialPort().bytesAvailable()];
-					event.getSerialPort().readBytes(buffer, buffer.length);
-					System.out.println("   Reading " + buffer.length + " bytes");
-				}
-				else
-				{
-					System.out.println("Received event type: LISTENING_EVENT_PORT_DISCONNECTED");
-				}
-			}
-		});
-		try { Thread.sleep(10000); } catch (Exception e) {}
-		ubxPort.closePort();*/
-
 		/*System.out.println("\n\nAttempting to read from two serial ports simultaneously\n");
 		System.out.println("\nAvailable Ports:\n");
 		for (int i = 0; i < ports.length; ++i)