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

void die_read(char *fn)
{
  fprintf(stderr,"bytestodecimal: fatal: unable to read %s: %s\n"
    ,fn,strerror(errno));
  exit(111);
}

void die_write(void)
{
  fprintf(stderr,"bytestodecimal: fatal: unable to write output: %s\n"
    ,strerror(errno));
  exit(111);
}

int main(int argc,char **argv)
{
  FILE *f;
  int bytes = 0;
  int c;

  if (!argv[1]) {
    fprintf(stderr,"usage: bytestodecimal f\n");
    exit(100);
  }

  f = fopen(argv[1],"r");
  if (!f) die_read(argv[1]);

  while ((c = fgetc(f)) != -1) {
    if (printf("%4d",c) == -1) die_write();
    if (++bytes == 10) {
      if (printf("\n") == -1) die_write();
      bytes = 0;
    }
  }
  if (ferror(f)) die_read(argv[1]);

  if (bytes)
    if (printf("\n") == -1) die_write();

  if (fflush(stdout) == -1) die_write();

  exit(0);
}