sapling/eden/fs/cli/util.py

#!/usr/bin/env python3
#
# Copyright (c) 2016, Facebook, Inc.
# All rights reserved.
#
# This source code is licensed under the BSD-style license found in the
# LICENSE file in the root directory of this source tree. An additional grant
# of patent rights can be found in the PATENTS file in the same directory.

import errno
import os
import pwd
import subprocess
import time


class TimeoutError(Exception):
    pass


def poll_until(function, timeout, interval=0.2, timeout_ex=None):
    '''
    Call the specified function repeatedly until it returns non-None.
    Returns the function result.

    Sleep 'interval' seconds between calls.  If 'timeout' seconds passes
    before the function returns a non-None result, raise an exception.
    If a 'timeout_ex' argument is supplied, that exception object is
    raised, otherwise a TimeoutError is raised.
    '''
    end_time = time.time() + timeout
    while True:
        result = function()
        if result is not None:
            return result

        if time.time() >= end_time:
            if timeout_ex is not None:
                raise timeout_ex
            raise TimeoutError('timed out waiting on function {}'.format(
                function.__name__))

        time.sleep(interval)


def get_home_dir():
    home_dir = None
    if os.name == 'nt':
        home_dir = os.getenv('USERPROFILE')
    else:
        home_dir = os.getenv('HOME')
    if not home_dir:
        home_dir = pwd.getpwuid(os.getuid()).pw_dir
    return home_dir


def mkdir_p(path):
    '''Performs `mkdir -p <path>` and returns the path.'''
    try:
        os.makedirs(path)
    except OSError as e:
        if e.errno != errno.EEXIST:
            raise
    return path


def is_git_dir(path):
    return (os.path.isdir(os.path.join(path, 'objects')) and
            os.path.isdir(os.path.join(path, 'refs')) and
            os.path.exists(os.path.join(path, 'HEAD')))


def get_git_dir(path):
    '''
    If path points to a git repository, return the path to the repository .git
    directory.  Otherwise, if the path is not a git repository, return None.
    '''
    path = os.path.realpath(path)
    if path.endswith('.git') and is_git_dir(path):
        return path

    git_subdir = os.path.join(path, '.git')
    if is_git_dir(git_subdir):
        return git_subdir

    return None


def get_git_commit(git_dir):
    cmd = ['git', 'rev-parse', 'HEAD']
    out = subprocess.check_output(cmd, cwd=git_dir)
    return out.strip().decode('utf-8', errors='surrogateescape')


def get_hg_repo(path):
    '''
    If path points to a mercurial repository, return a normalized path to the
    repository root.  Otherwise, if path is not a mercurial repository, return
    None.
    '''
    repo_path = os.path.realpath(path)
    hg_dir = os.path.join(repo_path, '.hg')
    if not os.path.isdir(hg_dir):
        return None

    # Check to see if this is a shared working directory from another
    # repository
    try:
        with open(os.path.join(hg_dir, 'sharedpath'), 'r') as f:
            hg_dir = f.readline().rstrip('\n')
            hg_dir = os.path.realpath(hg_dir)
            repo_path = os.path.dirname(hg_dir)
    except EnvironmentError as ex:
        if ex.errno != errno.ENOENT:
            raise

    if not os.path.isdir(os.path.join(hg_dir, 'store')):
        return None

    return repo_path


def get_hg_commit(repo):
    env = os.environ.copy()
    env['HGPLAIN'] = '1'
    cmd = ['hg', '--cwd', repo, 'log', '-T{node}\\n', '-r.']
    out = subprocess.check_output(cmd, env=env)
    return out.strip().decode('utf-8', errors='surrogateescape')


def get_repo_source_and_type(path):
    repo_source = ''
    repo_type = None
    git_dir = get_git_dir(path)
    if git_dir:
        repo_source = git_dir
        repo_type = 'git'
    else:
        hg_repo = get_hg_repo(path)
        if hg_repo:
            repo_source = hg_repo
            repo_type = 'hg'
    return (repo_source, repo_type)