#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

#define READBUFSIZE 128

/* Copy a file one byte at a time */

int main(int argc, char **argv) {
  FILE *fin, *fout;
  char readbuf[READBUFSIZE];
  size_t readlen;

  // Take the filenames from command line arguments
  if (argc != 3) {
    fprintf(stderr, "usage: ./cp_example infile outfile\n");
    return EXIT_FAILURE;  // defined in stdlib.h
  }

  // Open the input file
  fin = fopen(argv[1], "rb");  // "rb" --> read, binary mode
  if (fin == NULL) {
    fprintf(stderr, "%s -- ", argv[1]);
    perror("fopen for read failed");
    return EXIT_FAILURE;
  }

  // Open the output file
  fout = fopen(argv[2], "wb");  // "wb" --> truncate & write, binary mode
  if (fout == NULL) {
    fprintf(stderr, "%s -- ", argv[2]);
    perror("fopen for write failed");
    return EXIT_FAILURE;
  }


  // Read from the file, write to fout.
  while ((readlen = fread(readbuf, 1, READBUFSIZE, fin)) > 0) {
    if (fwrite(readbuf, 1, readlen, fout) < readlen) {
      perror("fwrite failed");
      return EXIT_FAILURE;
    }
  }

  // Test to see if we encountered an error while reading.
  if (ferror(fin)) {
    perror("fread failed");
    return EXIT_FAILURE;
  }
  fclose(fin);
  fclose(fout);

  return EXIT_SUCCESS;  // defined in stdlib.h
}