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# dockerpty: tty.py
#
# Copyright 2014 Chris Corbyn <[email protected]>
#
# 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)
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