/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8                               :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
│                                                                              │
│ Permission to use, copy, modify, and/or distribute this software for         │
│ any purpose with or without fee is hereby granted, provided that the         │
│ above copyright notice and this permission notice appear in all copies.      │
│                                                                              │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
│ PERFORMANCE OF THIS SOFTWARE.                                                │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/internal.h"
#include "libc/calls/struct/winsize.h"
#include "libc/calls/syscall-nt.internal.h"
#include "libc/calls/syscall-sysv.internal.h"
#include "libc/calls/syscall_support-sysv.internal.h"
#include "libc/errno.h"
#include "libc/intrin/strace.h"
#include "libc/sysv/consts/termios.h"
#include "libc/sysv/errfuns.h"

/**
 * Tells if file descriptor is a terminal.
 *
 * @param fd is file descriptor
 * @return 1 if is terminal, otherwise 0 w/ errno
 * @raise EBADF if fd isn't a valid file descriptor
 * @raise ENOTTY if fd is something other than a terminal
 * @raise EPERM if pledge() was used without tty
 */
bool32 isatty(int fd) {
  bool32 res;
  struct winsize ws;
  if (__isfdkind(fd, kFdZip)) {
    enotty();
    res = false;
  } else if (IsWindows() || IsMetal()) {
    res = sys_isatty(fd);
  } else if (!sys_ioctl(fd, TIOCGWINSZ, &ws)) {
    res = true;
  } else {
    res = false;
    if (errno != EBADF && errno != EPERM) {
      enotty();
    }
  }
  STRACE("isatty(%d) → %hhhd% m", fd, res);
  return res;
}
