Merge pull request #25 from tier4/feat/close_exist_port_on_start

feat: close GPIO port on node boot if is is already used

Author: drwnz

src/jetson_gpio.cpp

@@ -15,6 +15,7 @@
 #include <sensor_trigger/jetson_gpio.hpp>
 
 #include <cstdio>
+#include <sys/stat.h>
 
 namespace jetson_gpio
 {
@@ -65,6 +66,15 @@ bool JetsonGpio::export_gpio()
   int file_descriptor, buffer_length;
   char buffer[BUFFER_SIZE];
 
+  // Check target GPIO is available (not opened) first.
+  // If it is unavailable, close the port and try to open it.
+    std::string target_gpio = std::string(SYSFS_GPIO_DIR) + std::string("/gpio")
+                              + std::to_string(gpio_);
+  struct stat return_status;
+  if (stat(target_gpio.c_str(), &return_status) == 0) {
+       unexport_gpio();
+  }
+
   file_descriptor = open(SYSFS_GPIO_DIR "/export", O_WRONLY);
   if (file_descriptor < 0) {
     return false;