| # dockerpty: tty.py |
| # |
| # Copyright 2014 Chris Corbyn <chris@w3style.co.uk> |
| # |
| # Licensed under the Apache License, Version 2.0 (the "License"); |
| # you may not use this file except in compliance with the License. |
| # You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| |
| from __future__ import absolute_import |
| |
| import os |
| import termios |
| import tty |
| import fcntl |
| import struct |
| |
| |
| def size(fd): |
| """ |
| Return a tuple (rows,cols) representing the size of the TTY `fd`. |
| |
| The provided file descriptor should be the stdout stream of the TTY. |
| |
| If the TTY size cannot be determined, returns None. |
| """ |
| |
| if not os.isatty(fd.fileno()): |
| return None |
| |
| try: |
| dims = struct.unpack('hh', fcntl.ioctl(fd, termios.TIOCGWINSZ, 'hhhh')) |
| except: |
| try: |
| dims = (os.environ['LINES'], os.environ['COLUMNS']) |
| except: |
| return None |
| |
| return dims |
| |
| |
| class Terminal(object): |
| """ |
| Terminal provides wrapper functionality to temporarily make the tty raw. |
| |
| This is useful when streaming data from a pseudo-terminal into the tty. |
| |
| Example: |
| |
| with Terminal(sys.stdin, raw=True): |
| do_things_in_raw_mode() |
| """ |
| |
| def __init__(self, fd, raw=True): |
| """ |
| Initialize a terminal for the tty with stdin attached to `fd`. |
| |
| Initializing the Terminal has no immediate side effects. The `start()` |
| method must be invoked, or `with raw_terminal:` used before the |
| terminal is affected. |
| """ |
| |
| self.fd = fd |
| self.raw = raw |
| self.original_attributes = None |
| |
| |
| def __enter__(self): |
| """ |
| Invoked when a `with` block is first entered. |
| """ |
| |
| self.start() |
| return self |
| |
| |
| def __exit__(self, *_): |
| """ |
| Invoked when a `with` block is finished. |
| """ |
| |
| self.stop() |
| |
| |
| def israw(self): |
| """ |
| Returns True if the TTY should operate in raw mode. |
| """ |
| |
| return self.raw |
| |
| |
| def start(self): |
| """ |
| Saves the current terminal attributes and makes the tty raw. |
| |
| This method returns None immediately. |
| """ |
| |
| if os.isatty(self.fd.fileno()) and self.israw(): |
| self.original_attributes = termios.tcgetattr(self.fd) |
| tty.setraw(self.fd) |
| |
| |
| def stop(self): |
| """ |
| Restores the terminal attributes back to before setting raw mode. |
| |
| If the raw terminal was not started, does nothing. |
| """ |
| |
| if self.original_attributes is not None: |
| termios.tcsetattr( |
| self.fd, |
| termios.TCSADRAIN, |
| self.original_attributes, |
| ) |
| |
| def __repr__(self): |
| return "{cls}({fd}, raw={raw})".format( |
| cls=type(self).__name__, |
| fd=self.fd, |
| raw=self.raw) |
