#include <stdio.h>
#include <err.h>
#include <endian.h>
#include <stdint.h>
#include <sys/types.h>

#define ANSI_FG_RED "\033[0;31m"

/* This program pipes it's argument file to stdout prepending it */
/* with it's size (4 bytes, little endian). It is intended to be used */
/* with our bootloader (i.e. by piping kernel image to UART). */

int main(int argc, char **argv) {
  char *image_file_name = argc > 1 ? argv[1] : "kernel7.img";
  
  FILE *image_file_handle = fopen(image_file_name, "r");

  if (!image_file_handle)
    err(-1, "couldn't open" ANSI_FG_RED "%s", image_file_name);

  if (fseek(image_file_handle, 0, SEEK_END))
    err(-1, "error navigating through file");

  ssize_t image_size = ftell(image_file_handle);
  if (image_size < 0)
    err(-1, "couldn't get image file size");

  if (image_size >> 32)
    err(-1, "file to big (should be smaller than 4G)");

  if (fseek(image_file_handle, 0, SEEK_SET))
    err(-1, "error navigating through file");

  uint32_t image_size_le = htole32(image_size);

  if (fwrite(&image_size_le, 4, 1, stdout) != 1)
    err(-1, "couldn't write to stdout");

  ssize_t bytes_left = image_size;
  
  char buf[1024];

  while (bytes_left)
    {
      size_t bytes_read;
      if ((bytes_read = fread(buf, 1, sizeof(buf), image_file_handle))
	  < 1)
	err(-1, "error reading the file");

      if (fwrite(buf, bytes_read, 1, stdout) != 1)
	err(-1, "error writing to stdout");

      bytes_left -= bytes_read;
    }
}