#include<stdio.h>
#include<stdarg.h>
#include<fcntl.h>

#define PERMS 0666

void error(char *, ...);

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

   int f1, f2, n;
   char buf[BUFSIZ];

   if (argc != 3) error("Usage: cp1 from to");
   if ((f1 = open(argv[1], O_RDONLY, 0)) == -1)
       error("cp1: can't open %s", argv[1]);
   if ((f2 = creat(argv[2], PERMS)) == -1)
       error("cp1: can't create %s, mode %03o", argv[2], PERMS);

   while ((n = read(f1, buf, BUFSIZ)) > 0)
     if (write(f2, buf, n) != n)
        error("cp1: write error on file %s", argv[2]);

   return 0;
}

void error(char *fmt, ...)
 {
    va_list args;

    va_start(args, fmt);

    fprintf(stderr, "error: ");
    vfprintf(stderr, fmt, args);
    fprintf(stderr, "\n");

    va_end(args);
    exit(1);
 }