Source code for Exscript.util.tty

#
# Copyright (C) 2010-2017 Samuel Abels
# The MIT License (MIT)
#
# 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.
"""
TTY utilities.
"""
import os
import sys
import struct
from subprocess import Popen, PIPE
from builtins import int

def _get_terminal_size(fd):
    try:
        import fcntl
        import termios
    except ImportError:
        return None
    s = struct.pack('HHHH', 0, 0, 0, 0)
    try:
        x = fcntl.ioctl(fd, termios.TIOCGWINSZ, s)
    except IOError:  # Window size ioctl not supported.
        return None
    try:
        rows, cols, x_pixels, y_pixels = struct.unpack('HHHH', x)
    except struct.error:
        return None
    return rows, cols


[docs]def get_terminal_size(default_rows=25, default_cols=80): """ Returns the number of lines and columns of the current terminal. It attempts several strategies to determine the size and if all fail, it returns (80, 25). :rtype: int, int :return: The rows and columns of the terminal. """ # Collect a list of viable input channels that may tell us something # about the terminal dimensions. fileno_list = [] try: fileno_list.append(sys.stdout.fileno()) except AttributeError: # Channel was redirected to an object that has no fileno() pass except ValueError: # Channel was closed while attempting to read it pass try: fileno_list.append(sys.stdin.fileno()) except AttributeError: pass except ValueError: # Channel was closed while attempting to read it pass try: fileno_list.append(sys.stderr.fileno()) except AttributeError: pass except ValueError: # Channel was closed while attempting to read it pass # Ask each channel for the terminal window size. for fd in fileno_list: try: rows, cols = _get_terminal_size(fd) except TypeError: # _get_terminal_size() returned None. pass else: return rows, cols # Try os.ctermid() try: fd = os.open(os.ctermid(), os.O_RDONLY) except AttributeError: # os.ctermid does not exist on Windows. pass except OSError: # The device pointed to by os.ctermid() does not exist. pass else: try: rows, cols = _get_terminal_size(fd) except TypeError: # _get_terminal_size() returned None. pass else: return rows, cols finally: os.close(fd) # Try `stty size` with open(os.devnull, 'w') as devnull: try: process = Popen(['stty', 'size'], stderr=devnull, stdout=PIPE, close_fds=True) except (OSError, ValueError): pass else: errcode = process.wait() output = process.stdout.read() try: rows, cols = output.split() return int(rows), int(cols) except (ValueError, TypeError): pass # Try environment variables. try: return tuple(int(os.getenv(var)) for var in ('LINES', 'COLUMNS')) except (ValueError, TypeError): pass # Give up. return default_rows, default_cols