snipplets.dev/code/C/libserialport/listen.c

#include <libserialport.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <signal.h>

/* Helper function for error handling. */
int check(enum sp_return result);
void handle_sigint(int sig);

bool INTERRUPT = false;

int main(int argc, char **argv) {
  struct sp_port *serial_port;
  char *port_name;

  const int size = 256;
  char *buffer = malloc(size + 1);

  const unsigned int timeout = 1000;
  int result;

  /* Get the port name from the command line. */
  if (argc != 2) {
    printf("Usage: %s <port>\n\n", argv[0]);

    struct sp_port **port_list;
    enum sp_return result = sp_list_ports(&port_list);

    /* Getting the available ports. */
    if (result != SP_OK) {
      puts("Getting available ports failed!");
    } else {
      puts("Available ports:");

      int i;
      for (i = 0; port_list[i] != NULL; i++) {
        /* Get the name of the port. */
        struct sp_port *port = port_list[i];
        char *port_name = sp_get_port_name(port);

        printf("  * %s\n", port_name);
      }

      printf("\nAvailable %d ports.\n", i);

      sp_free_port_list(port_list);
    }

    return -1;
  } else {
    port_name = argv[1];
  }

  printf("Connecting to '%s'...\n", port_name);
  check(sp_get_port_by_name(port_name, &serial_port));
  check(sp_open(serial_port, SP_MODE_READ_WRITE));

  check(sp_set_baudrate(serial_port, 9600));
  check(sp_set_bits(serial_port, 8));
  check(sp_set_parity(serial_port, SP_PARITY_NONE));
  check(sp_set_stopbits(serial_port, 1));
  check(sp_set_flowcontrol(serial_port, SP_FLOWCONTROL_NONE));
  puts("Connected.");

  signal(SIGINT, handle_sigint);

  FILE *output_file;
  output_file = fopen("./abc.txt", "w");

  /* Reading lines from serial port. */
  bool reading = true;
  while (reading && !INTERRUPT) {
    int pos = 0;

    /* Character-by-character reading. */
    while (pos < size) {
      result = check(sp_blocking_read(serial_port, buffer + pos, 1, timeout));

      if (result == -1) {
        puts("Error reading from serial port");

        reading = false;
        break;
      } else if (result == 0) {
        puts("No more data");
        break;
      } else {
        if (buffer[pos] == '\n') {
          buffer[pos] = '\0';
          break;
        }

        pos++;
      }
    }

    puts(buffer);
    fputs(buffer, output_file);
  }

  fclose(output_file);
  free(buffer);

  return 0;
}

/* Helper function for error handling. */
int check(enum sp_return result) {
  char *error_message;

  switch (result) {
  case SP_ERR_ARG:
    puts("Error: Invalid argument.");
    abort();
  case SP_ERR_FAIL:
    error_message = sp_last_error_message();
    printf("Error: Failed: %s\n", error_message);
    sp_free_error_message(error_message);
    abort();
  case SP_ERR_SUPP:
    puts("Error: Not supported.");
    abort();
  case SP_ERR_MEM:
    puts("Error: Couldn't allocate memory.");
    abort();
  case SP_OK:
  default:
    return result;
  }
}

void handle_sigint(int sig) { INTERRUPT = true; }