115 lines
4.2 KiB
Python
115 lines
4.2 KiB
Python
# -*- coding: utf-8 -*- #
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# Copyright 2013 Google LLC. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""General console printing utilities used by the Cloud SDK."""
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from __future__ import absolute_import
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from __future__ import division
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from __future__ import print_function
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import os
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import signal
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import subprocess
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import sys
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from fire.console import console_attr
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from fire.console import console_pager
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from fire.console import encoding
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from fire.console import files
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def IsInteractive(output=False, error=False, heuristic=False):
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"""Determines if the current terminal session is interactive.
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sys.stdin must be a terminal input stream.
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Args:
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output: If True then sys.stdout must also be a terminal output stream.
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error: If True then sys.stderr must also be a terminal output stream.
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heuristic: If True then we also do some additional heuristics to check if
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we are in an interactive context. Checking home path for example.
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Returns:
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True if the current terminal session is interactive.
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"""
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if not sys.stdin.isatty():
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return False
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if output and not sys.stdout.isatty():
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return False
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if error and not sys.stderr.isatty():
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return False
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if heuristic:
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# Check the home path. Most startup scripts for example are executed by
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# users that don't have a home path set. Home is OS dependent though, so
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# check everything.
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# *NIX OS usually sets the HOME env variable. It is usually '/home/user',
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# but can also be '/root'. If it's just '/' we are most likely in an init
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# script.
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# Windows usually sets HOMEDRIVE and HOMEPATH. If they don't exist we are
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# probably being run from a task scheduler context. HOMEPATH can be '\'
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# when a user has a network mapped home directory.
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# Cygwin has it all! Both Windows and Linux. Checking both is perfect.
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home = os.getenv('HOME')
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homepath = os.getenv('HOMEPATH')
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if not homepath and (not home or home == '/'):
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return False
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return True
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def More(contents, out, prompt=None, check_pager=True):
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"""Run a user specified pager or fall back to the internal pager.
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Args:
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contents: The entire contents of the text lines to page.
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out: The output stream.
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prompt: The page break prompt.
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check_pager: Checks the PAGER env var and uses it if True.
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"""
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if not IsInteractive(output=True):
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out.write(contents)
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return
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if check_pager:
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pager = encoding.GetEncodedValue(os.environ, 'PAGER', None)
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if pager == '-':
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# Use the fallback Pager.
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pager = None
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elif not pager:
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# Search for a pager that handles ANSI escapes.
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for command in ('less', 'pager'):
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if files.FindExecutableOnPath(command):
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pager = command
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break
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if pager:
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# If the pager is less(1) then instruct it to display raw ANSI escape
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# sequences to enable colors and font embellishments.
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less_orig = encoding.GetEncodedValue(os.environ, 'LESS', None)
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less = '-R' + (less_orig or '')
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encoding.SetEncodedValue(os.environ, 'LESS', less)
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# Ignore SIGINT while the pager is running.
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# We don't want to terminate the parent while the child is still alive.
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signal.signal(signal.SIGINT, signal.SIG_IGN)
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p = subprocess.Popen(pager, stdin=subprocess.PIPE, shell=True)
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enc = console_attr.GetConsoleAttr().GetEncoding()
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p.communicate(input=contents.encode(enc))
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p.wait()
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# Start using default signal handling for SIGINT again.
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signal.signal(signal.SIGINT, signal.SIG_DFL)
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if less_orig is None:
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encoding.SetEncodedValue(os.environ, 'LESS', None)
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return
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# Fall back to the internal pager.
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console_pager.Pager(contents, out, prompt).Run()
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