/*
A different solution would read f1
into a dynamically allocated array,
then write the array to f2.
This solution is simpler and works for files that don't fit into memory.
*/

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

void die_usage(void)
{
  fprintf(stderr,"usage: copy f1 f2\n");
  exit(100);
}

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

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

int main(int argc,char **argv)
{
  FILE *f1;
  FILE *f2;
  char c;

  if (argc < 3) die_usage();
  f1 = fopen(argv[1],"r");
  if (!f1) die_read(argv[1]);
  f2 = fopen(argv[2],"w");
  if (!f2) die_write(argv[2]);

  while (fscanf(f1,"%c",&c) == 1)
    if (fprintf(f2,"%c",c) == -1) die_write(argv[2]);

  if (ferror(f1)) die_read(argv[1]);
  if (fflush(f2) == -1) die_write(argv[2]);

  exit(0);
}