libuv/src/unix/tty.c

/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include "uv.h"
#include "internal.h"
#include "spinlock.h"

#include <assert.h>
#include <unistd.h>
#include <termios.h>
#include <errno.h>
#include <sys/ioctl.h>

static int orig_termios_fd = -1;
static struct termios orig_termios;
static uv_spinlock_t termios_spinlock = UV_SPINLOCK_INITIALIZER;


int uv_tty_init(uv_loop_t* loop, uv_tty_t* tty, int fd, int readable) {
  int flags;
  int newfd;
  int r;

  flags = 0;
  newfd = -1;

  uv__stream_init(loop, (uv_stream_t*) tty, UV_TTY);

  /* Reopen the file descriptor when it refers to a tty. This lets us put the
   * tty in non-blocking mode without affecting other processes that share it
   * with us.
   *
   * Example: `node | cat` - if we put our fd 0 in non-blocking mode, it also
   * affects fd 1 of `cat` because both file descriptors refer to the same
   * struct file in the kernel. When we reopen our fd 0, it points to a
   * different struct file, hence changing its properties doesn't affect
   * other processes.
   */
  if (isatty(fd)) {
    r = uv__open_cloexec("/dev/tty", O_RDWR);

    if (r < 0) {
      /* fallback to using blocking writes */
      if (!readable)
        flags |= UV_STREAM_BLOCKING;
      goto skip;
    }

    newfd = r;

    r = uv__dup2_cloexec(newfd, fd);
    if (r < 0 && r != -EINVAL) {
      /* EINVAL means newfd == fd which could conceivably happen if another
       * thread called close(fd) between our calls to isatty() and open().
       * That's a rather unlikely event but let's handle it anyway.
       */
      uv__close(newfd);
      return r;
    }

    fd = newfd;
  }

skip:
#if defined(__APPLE__)
  r = uv__stream_try_select((uv_stream_t*) tty, &fd);
  if (r) {
    if (newfd != -1)
      uv__close(newfd);
    return r;
  }
#endif

  if (readable)
    flags |= UV_STREAM_READABLE;
  else
    flags |= UV_STREAM_WRITABLE;

  if (!(flags & UV_STREAM_BLOCKING))
    uv__nonblock(fd, 1);

  uv__stream_open((uv_stream_t*) tty, fd, flags);
  tty->mode = 0;

  return 0;
}


int uv_tty_set_mode(uv_tty_t* tty, int mode) {
  struct termios raw;
  int fd;

  fd = uv__stream_fd(tty);

  if (mode && tty->mode == 0) {  /* on */
    if (tcgetattr(fd, &tty->orig_termios))
      return -errno;

    /* This is used for uv_tty_reset_mode() */
    uv_spinlock_lock(&termios_spinlock);
    if (orig_termios_fd == -1) {
      orig_termios = tty->orig_termios;
      orig_termios_fd = fd;
    }
    uv_spinlock_unlock(&termios_spinlock);

    raw = tty->orig_termios;
    cfmakeraw(&raw);

    /* Put terminal in raw mode after draining */
    if (tcsetattr(fd, TCSADRAIN, &raw))
      return -errno;

    tty->mode = 1;
  } else if (mode == 0 && tty->mode) {  /* off */
    /* Put terminal in original mode after flushing */
    if (tcsetattr(fd, TCSAFLUSH, &tty->orig_termios))
      return -errno;
    tty->mode = 0;
  }

  return 0;
}


int uv_tty_get_winsize(uv_tty_t* tty, int* width, int* height) {
  struct winsize ws;

  if (ioctl(uv__stream_fd(tty), TIOCGWINSZ, &ws))
    return -errno;

  *width = ws.ws_col;
  *height = ws.ws_row;

  return 0;
}


uv_handle_type uv_guess_handle(uv_file file) {
  struct sockaddr sa;
  struct stat s;
  socklen_t len;
  int type;

  if (file < 0)
    return UV_UNKNOWN_HANDLE;

  if (isatty(file))
    return UV_TTY;

  if (fstat(file, &s))
    return UV_UNKNOWN_HANDLE;

  if (S_ISREG(s.st_mode))
    return UV_FILE;

  if (S_ISCHR(s.st_mode))
    return UV_FILE;  /* XXX UV_NAMED_PIPE? */

  if (S_ISFIFO(s.st_mode))
    return UV_NAMED_PIPE;

  if (!S_ISSOCK(s.st_mode))
    return UV_UNKNOWN_HANDLE;

  len = sizeof(type);
  if (getsockopt(file, SOL_SOCKET, SO_TYPE, &type, &len))
    return UV_UNKNOWN_HANDLE;

  len = sizeof(sa);
  if (getsockname(file, &sa, &len))
    return UV_UNKNOWN_HANDLE;

  if (type == SOCK_DGRAM)
    if (sa.sa_family == AF_INET || sa.sa_family == AF_INET6)
      return UV_UDP;

  if (type == SOCK_STREAM) {
    if (sa.sa_family == AF_INET || sa.sa_family == AF_INET6)
      return UV_TCP;
    if (sa.sa_family == AF_UNIX)
      return UV_NAMED_PIPE;
  }

  return UV_UNKNOWN_HANDLE;
}


/* This function is async signal-safe, meaning that it's safe to call from
 * inside a signal handler _unless_ execution was inside uv_tty_set_mode()'s
 * critical section when the signal was raised.
 */
int uv_tty_reset_mode(void) {
  int err;

  if (!uv_spinlock_trylock(&termios_spinlock))
    return -EBUSY;  /* In uv_tty_set_mode(). */

  err = 0;
  if (orig_termios_fd != -1)
    if (tcsetattr(orig_termios_fd, TCSANOW, &orig_termios))
      err = -errno;

  uv_spinlock_unlock(&termios_spinlock);
  return err;
}