#include <unistd.h>
#include <errno.h>

void __procfdname(char*, unsigned);

int ttyname_r(int fd, char* name, size_t size) {
  char procname[sizeof "/proc/self/fd/" + 3 * sizeof(int) + 2];
  ssize_t l;

  if (!isatty(fd))
    return ENOTTY;

  __procfdname(procname, fd);
  l = readlink(procname, name, size);

  if (l < 0)
    return errno;
  else if (l == size)
    return ERANGE;
  else {
    name[l] = 0;
    return 0;
  }
}