Here's a revised cpio. I've reduced the use of malloc(), dropped an extra function call, and -at least in theory- allowed proper handling of non-regular files. (If we have a file we can't read, we still should record it when it's of a type where file content is ignored).

#include "toys.h"
#include "toynet.h"

int xsocket(int domain, int type, int protocol)
{
  int fd = socket(domain, type, protocol);

  if (fd < 0) perror_exit("socket %x %x", type, protocol);
  return fd;
}