Robotd/robotd.c

#include <Python.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include <syslog.h>
#include <stdbool.h>
#include <mraa.h>

#define GPIO_PIN_4 4
#define GPIO_PIN_13 13

#define MRAA_CHECK_RESULT(X, Y, Z, Q)		\
  if (X == MRAA_SUCCESS) {			\
    syslog(LOG_DAEMON | LOG_NOTICE, Y);		\
  } else {					\
    syslog(LOG_DAEMON | LOG_ERR, Z);		\
    if (Q) {					\
      clean_up();				\
      exit(EXIT_FAILURE);			\
    }						\
  }

#define PYTHON_CHECK_RESULT(X, Y, Z, W)				\
  if (X == 0) {							\
    syslog(LOG_DAEMON | LOG_NOTICE, Y);				\
  } else if (X == 1) {						\
    syslog(LOG_DAEMON | LOG_ERR, Z);				\
    clean_up();							\
    exit(EXIT_FAILURE);						\
  } else if (X == 2) {						\
    syslog(LOG_DAEMON | LOG_ERR, W);				\
    clean_up();							\
    exit(EXIT_FAILURE);						\
  } else {							\
    syslog(LOG_DAEMON | LOG_ERR, "Python returned %d", X);	\
    clean_up();							\
    exit(EXIT_FAILURE);						\
  }

mraa_result_t     mr;
mraa_gpio_context pin13, pin4;

void clean_up() {
  syslog(LOG_DAEMON | LOG_WARNING, "Cleaning up.");
  mr = mraa_gpio_write(pin4, 0);
  MRAA_CHECK_RESULT(mr, "Red LED turned off.", "Failed to turn off the red LED.", false)
  closelog();
}

void sig_handler(int signal) {
  syslog(LOG_DAEMON | LOG_WARNING, "Robot daemon interrupted.");
  clean_up();
  exit(EXIT_FAILURE);
}

int main(int argc, char ** argv) {
  int          rv;
  bool         done = false;
  sighandler_t sh;

  // Turn the process into a daemon.
  rv = daemon(0, 1);

  if (rv != 0) {
    perror("daemon(0, 1)");
    return EXIT_FAILURE;
  }

  // Set SIGINT signal handler
  sh = signal(SIGINT, sig_handler);

  if (sh == SIG_ERR) {
    perror("sh = signal(SIGINT, sig_handler)");
    return EXIT_FAILURE;
  }

  // Create PID file
  FILE * pid = fopen("/var/run/robot.pid", "w");

  if (pid == NULL) {
    perror("FILE * pid = fopen(\"/var/run/robot.pid\", \"w\")");
    syslog(LOG_DAEMON | LOG_ERR, "Failed to create PID file.");
    return EXIT_FAILURE;
  }

  fprintf(pid, "%d", getpid());
  fclose(pid);
  
  // Open a syslog connection
  openlog(argv[0], LOG_NDELAY | LOG_PID, LOG_DAEMON);
  syslog(LOG_DAEMON | LOG_NOTICE, "Started robot daemon.");

  // Open PIN 13 as a PULLUP input pin for the push button
  pin13 = mraa_gpio_init(GPIO_PIN_13);
  mr = mraa_gpio_dir(pin13, MRAA_GPIO_IN);
  MRAA_CHECK_RESULT(mr, "Opened push button pin.", "Failed to open push button pin.", true);
  mr = mraa_gpio_mode(pin13, MRAA_GPIO_PULLUP);
  MRAA_CHECK_RESULT(mr, "Push button ready.", "Failed to set push button mode.", true);

  // Open PIN 4 as an output pin for the red indicator LED
  pin4 = mraa_gpio_init(GPIO_PIN_4);
  mr = mraa_gpio_dir(pin4, MRAA_GPIO_OUT);
  MRAA_CHECK_RESULT(mr, "Red LED ready.", "Failed to open red LED pin.", true);

  // Start pin processing loop
  while (!done) {
    // Keep the red LED on and read from the push button pin
    mr = mraa_gpio_write(pin4, 1);

    if (mr != MRAA_SUCCESS) {
      syslog(LOG_DAEMON | LOG_ERR, "Failed to write to the red LED.");
    }
    
    rv = mraa_gpio_read(pin13);

    if (rv == 0) {
      // If the button is pressed then stop reading and go on with the program
      syslog(LOG_DAEMON | LOG_NOTICE, "Button push detected.");
      done = true;
    }
  }

  // Open the source code file for the Python script
  syslog(LOG_DAEMON | LOG_NOTICE, "Opening Python source code.");
  FILE * code = fopen("/home/root/Robotd/robot.py", "r");

  if (code == NULL) {
    perror("FILE * code = fopen(\"/home/root/Robotd/robot.py\", \"r\")");
    syslog(LOG_DAEMON | LOG_NOTICE, "Failed to load Python program.");
    clean_up();
    return EXIT_FAILURE;
  }

  // Return SIGINT handler to it's default state
  sh = signal(SIGINT, SIG_DFL);

  if (sh == SIG_ERR) {
    perror("sh = signal(SIGINT, SIG_DLF)");
    syslog(LOG_DAEMON | LOG_NOTICE, "Failed to disable signal handler.");
    clean_up();
    return EXIT_FAILURE;
  }
  
  // Execute the Python code
  syslog(LOG_DAEMON | LOG_NOTICE, "Performing Python call.");  
  Py_SetProgramName(argv[0]);
  Py_Initialize();
  rv = PyRun_SimpleFile(code, "/home/root/Robotd/robot.py");
  PYTHON_CHECK_RESULT(rv, "robot.py success", "robot.py exception", "robot.py failure")
  Py_Finalize();

  // Close the source code file
  fclose(code);
  
  // Clean up and leave
  syslog(LOG_DAEMON | LOG_NOTICE, "Finishing.");
  closelog();
  //execlp("shutdown", "shutdown", "-Ph", "now", (char *)NULL);

  return EXIT_SUCCESS;
}