xonsh/xontrib/free_cwd.py

""" This will release the lock on the current directory whenever the
    prompt is shown. Enabling this will allow other programs or
    Windows Explorer to delete or rename the current or parent
    directories. Internally, it is accomplished by temporarily resetting
    CWD to the root drive folder while waiting at the prompt. This only
    works with the prompt_toolkit backend and can cause cause issues
    if any extensions are enabled that hook the prompt and relies on
    ``os.getcwd()``.
"""
import os
import builtins
import functools
from pathlib import Path

from xonsh.tools import print_exception
from xonsh.platform import ON_WINDOWS, ON_CYGWIN, ON_MSYS


def _chdir_up(path):
    """ Change directory to path or if path does not exist
        the first valid parent.
    """
    path = Path(path)
    try:
        os.chdir(path)
        return str(path.absolute())
    except (FileNotFoundError, NotADirectoryError):
        path.resolve()
        return _chdir_up(path.parent)


def _cwd_release_wrapper(func):
    """ Decorator for Windows to wrap the prompt function and release
        the process lock on the current directory while the prompt is
        displayed. This works by temporarily setting
        the workdir to the users home directory.
    """
    env = builtins.__xonsh__.env
    if env.get('UPDATE_PROMPT_ON_KEYPRESS'):
        return func if not hasattr(func, '_orgfunc') else func._orgfunc

    if hasattr(func, '_orgfunc'):
        # Already wrapped
        return func
    else:
        @functools.wraps(func)
        def wrapper(*args, **kwargs):
            anchor = Path(os.getcwd()).anchor
            os.chdir(anchor)
            try:
                out = func(*args, **kwargs)
            finally:
                try:
                    pwd = env.get('PWD', anchor)
                    os.chdir(pwd)
                except (FileNotFoundError, NotADirectoryError):
                    print_exception()
                    newpath = _chdir_up(pwd)
                    builtins.__xonsh__.env['PWD'] = newpath
                    raise KeyboardInterrupt
            return out
        wrapper._orgfunc = func
        return wrapper


def _cwd_restore_wrapper(func):
    """ Decorator for Windows which will temporary restore the true working
        directory. Designed to wrap completer callbacks from the
        prompt_toolkit or readline.
    """
    env = builtins.__xonsh__.env
    if env.get('UPDATE_PROMPT_ON_KEYPRESS'):
        return func if not hasattr(func, '_orgfunc') else func._orgfunc

    if hasattr(func, '_orgfunc'):
        # Already wrapped
        return func
    else:
        @functools.wraps(func)
        def wrapper(*args, **kwargs):
            workdir = os.getcwd()
            _chdir_up(env.get('PWD', workdir))
            out = func(*args, **kwargs)
            _chdir_up(workdir)
            return out
        wrapper._orgfunc = func
        return wrapper


@events.on_ptk_create
def setup_release_cwd_hook(prompter, history, completer, bindings, **kw):
    if ON_WINDOWS and not ON_CYGWIN and not ON_MSYS:
        prompter.prompt = _cwd_release_wrapper(prompter.prompt)
        if completer.completer:
            # Temporarily restore cwd for callbacks to the completer
            completer.completer.complete = _cwd_restore_wrapper(completer.completer.complete)