util: fix reading sysfs

src/configfsisomanager.cpp

@@ -25,7 +25,7 @@ char *get_gadget_root()
 			{
 				gadgetRoot = strjin(usbGadgetRoot, entry->d_name);
 				udc = sysfs_read(strjin(gadgetRoot, "/UDC"));
-				if (strcmp(udc, getprop("sys.usb.controller")) == 1)
+				if (strcmp(udc, getprop("sys.usb.controller")) == 0)
 					break;
 			}
 		}

src/util.cpp

@@ -65,13 +65,19 @@ void sysfs_write(char *path, char *content)
 
 char *sysfs_read(char *path)
 {
-	char *value = nullptr;
+	std::string value;
 	std::ifstream sysfsFile(path);
-	sysfsFile >> path;
+	if (!sysfsFile.is_open())
+	{
+		return nullptr;
+	}
+	sysfsFile >> value;
 	sysfsFile.close();
-	return value;
+	char *result = new char[value.length() + 1];
-}
+	strcpy(result, value.c_str());
+	return result;
 	
+}
 
 char *getprop(char *key)
 {