Tooltron

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <termios.h>

#include <unistd.h>

#include <stdio.h>

#include <stdarg.h>

#include <stdlib.h>

#include <string.h>

#define RFID_OK 1

static char read_cmd[] = {'!', 'R', 'W', 1, 32};

static int serno;

void init_tty(int fd) {

  struct termios ios;

  bzero(&ios, sizeof(ios));

  ios.c_cflag = B9600 | CS8 | CREAD;

  tcsetattr(fd, TCSAFLUSH, &ios);

}

int bswap(int x) {

  return ((x&0xff) << 24) | ((x&0xff00) << 8)

    | ((x>>8) & 0xff00) | ((x>>24) & 0xff);

}

void read_all(int fd, void *buf, int n) {

  int nread;

  while (n > 0) {

    nread = read(fd, buf, n);

    buf += nread;

    n -= nread;

    usleep(10000);

  }

}

void write_all(int fd, void *buf, int n) {

  int nwritten;

  while (n > 0) {

    nwritten = write(fd, buf, n);

    buf += nwritten;

    n -= nwritten;

    usleep(10000);

  }

}

void fail_error(const char *error, ...) {

  va_list args;

  va_start(args, error);

  printf("Status: 500 Internal Server Error\n");

  printf("Content-type: text/plain\n\n");

  vprintf(error, args);

  va_end(args);

  exit(0);

}

int main(int argc, char **argv) {

  int fd;

  char status;

  fd = open("/dev/ttyUSB0", O_RDWR | O_NOCTTY);

  if (fd < 0)

    fail_error("Could not open /dev/ttyUSB0\n");

  init_tty(fd);

  tcflush(fd, TCIFLUSH);

  write_all(fd, read_cmd, sizeof(read_cmd));

  read_all(fd, &status, 1);

  if (status == RFID_OK) {

    read_all(fd, &serno, 4);

    serno = bswap(serno);

    printf("Content-type: text/plain\n\n");

    printf("%08x\n", serno);

  } else {

    fail_error("Reader gave error %d\n", (int)(unsigned char)status);

  }

  close(fd);

  return 0;

}