mercurial/pure/osutil.py
author Matt Harbison <matt_harbison@yahoo.com>
Sun, 29 Sep 2024 02:03:20 -0400
changeset 51934 09f3a6790e56
parent 51863 f4733654f144
permissions -rw-r--r--
interfaces: add the optional `bdiff.xdiffblocks()` method PyCharm flagged where this was called on the protocol class in `mdiff.py` in the previous commit, but pytype completely missed it. PyCharm is correct here, but I'm committing this separately to highlight this potential problem- some of the implementations don't implement _all_ of the methods the others do, and there's not a great way to indicate on a protocol class that a method or attribute is optional- that's kinda the opposite of what static typing is about. Making the method an `Optional[Callable]` attribute works here, and keeps both PyCharm and pytype happy, and the generated `mdiff.pyi` and `modules.pyi` look reasonable. We might be getting a little lucky, because the method isn't invoked directly- it is returned from another method that selects which block function to use. Except since it is declared on the protocol class, every module needs this attribute (in theory, but in practice this doesn't seem to be checked), so the check for it on the module has to change from `hasattr()` to `getattr(..., None)`. We defer defining the optional attrs to the type checking phase as an extra precaution- that way it isn't an attr with a `None` value at runtime if someone is still using `hasattr()`. As to why pytype missed this, I have no clue. The generated `mdiff.pyi` even has the global variable typed as `bdiff: intmod.BDiff`, so uses of it really should comply with what is on the class, protocol class or not.

# osutil.py - pure Python version of osutil.c
#
#  Copyright 2009 Olivia Mackall <olivia@selenic.com> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import annotations

import ctypes
import ctypes.util
import os
import stat as statmod

from .. import (
    encoding,
    pycompat,
)


def _mode_to_kind(mode):
    if statmod.S_ISREG(mode):
        return statmod.S_IFREG
    if statmod.S_ISDIR(mode):
        return statmod.S_IFDIR
    if statmod.S_ISLNK(mode):
        return statmod.S_IFLNK
    if statmod.S_ISBLK(mode):
        return statmod.S_IFBLK
    if statmod.S_ISCHR(mode):
        return statmod.S_IFCHR
    if statmod.S_ISFIFO(mode):
        return statmod.S_IFIFO
    if statmod.S_ISSOCK(mode):
        return statmod.S_IFSOCK
    return mode


def listdir(path, stat=False, skip=None):
    """listdir(path, stat=False) -> list_of_tuples

    Return a sorted list containing information about the entries
    in the directory.

    If stat is True, each element is a 3-tuple:

      (name, type, stat object)

    Otherwise, each element is a 2-tuple:

      (name, type)
    """
    result = []
    prefix = path
    if not prefix.endswith(pycompat.ossep):
        prefix += pycompat.ossep
    names = os.listdir(path)
    names.sort()
    for fn in names:
        st = os.lstat(prefix + fn)
        if fn == skip and statmod.S_ISDIR(st.st_mode):
            return []
        if stat:
            result.append((fn, _mode_to_kind(st.st_mode), st))
        else:
            result.append((fn, _mode_to_kind(st.st_mode)))
    return result


if not pycompat.iswindows:
    posixfile = open


else:
    import msvcrt

    _kernel32 = ctypes.windll.kernel32  # pytype: disable=module-attr

    _DWORD = ctypes.c_ulong
    _LPCSTR = _LPSTR = ctypes.c_char_p
    _HANDLE = ctypes.c_void_p

    _INVALID_HANDLE_VALUE = _HANDLE(-1).value

    # CreateFile
    _FILE_SHARE_READ = 0x00000001
    _FILE_SHARE_WRITE = 0x00000002
    _FILE_SHARE_DELETE = 0x00000004

    _CREATE_ALWAYS = 2
    _OPEN_EXISTING = 3
    _OPEN_ALWAYS = 4

    _GENERIC_READ = 0x80000000
    _GENERIC_WRITE = 0x40000000

    _FILE_ATTRIBUTE_NORMAL = 0x80

    # open_osfhandle flags
    _O_RDONLY = 0x0000
    _O_RDWR = 0x0002
    _O_APPEND = 0x0008

    _O_TEXT = 0x4000
    _O_BINARY = 0x8000

    # types of parameters of C functions used (required by pypy)

    _kernel32.CreateFileA.argtypes = [
        _LPCSTR,
        _DWORD,
        _DWORD,
        ctypes.c_void_p,
        _DWORD,
        _DWORD,
        _HANDLE,
    ]
    _kernel32.CreateFileA.restype = _HANDLE

    def _raiseioerror(name):
        err = ctypes.WinError()  # pytype: disable=module-attr
        raise IOError(
            err.errno, '%s: %s' % (encoding.strfromlocal(name), err.strerror)
        )

    class posixfile:
        """a file object aiming for POSIX-like semantics

        CPython's open() returns a file that was opened *without* setting the
        _FILE_SHARE_DELETE flag, which causes rename and unlink to abort.
        This even happens if any hardlinked copy of the file is in open state.
        We set _FILE_SHARE_DELETE here, so files opened with posixfile can be
        renamed and deleted while they are held open.
        Note that if a file opened with posixfile is unlinked, the file
        remains but cannot be opened again or be recreated under the same name,
        until all reading processes have closed the file."""

        def __init__(self, name, mode=b'r', bufsize=-1):
            if b'b' in mode:
                flags = _O_BINARY
            else:
                flags = _O_TEXT

            m0 = mode[0:1]
            if m0 == b'r' and b'+' not in mode:
                flags |= _O_RDONLY
                access = _GENERIC_READ
            else:
                # work around http://support.microsoft.com/kb/899149 and
                # set _O_RDWR for 'w' and 'a', even if mode has no '+'
                flags |= _O_RDWR
                access = _GENERIC_READ | _GENERIC_WRITE

            if m0 == b'r':
                creation = _OPEN_EXISTING
            elif m0 == b'w':
                creation = _CREATE_ALWAYS
            elif m0 == b'a':
                creation = _OPEN_ALWAYS
                flags |= _O_APPEND
            else:
                raise ValueError("invalid mode: %s" % pycompat.sysstr(mode))

            fh = _kernel32.CreateFileA(
                name,
                access,
                _FILE_SHARE_READ | _FILE_SHARE_WRITE | _FILE_SHARE_DELETE,
                None,
                creation,
                _FILE_ATTRIBUTE_NORMAL,
                None,
            )
            if fh == _INVALID_HANDLE_VALUE:
                _raiseioerror(name)

            fd = msvcrt.open_osfhandle(fh, flags)  # pytype: disable=module-attr
            if fd == -1:
                _kernel32.CloseHandle(fh)
                _raiseioerror(name)

            f = os.fdopen(fd, pycompat.sysstr(mode), bufsize)
            # unfortunately, f.name is '<fdopen>' at this point -- so we store
            # the name on this wrapper. We cannot just assign to f.name,
            # because that attribute is read-only.
            object.__setattr__(self, 'name', name)
            object.__setattr__(self, '_file', f)

        def __iter__(self):
            return self._file

        def __getattr__(self, name):
            return getattr(self._file, name)

        def __setattr__(self, name, value):
            """mimics the read-only attributes of Python file objects
            by raising 'TypeError: readonly attribute' if someone tries:
              f = posixfile('foo.txt')
              f.name = 'bla'
            """
            return self._file.__setattr__(name, value)

        def __enter__(self):
            self._file.__enter__()
            return self

        def __exit__(self, exc_type, exc_value, exc_tb):
            return self._file.__exit__(exc_type, exc_value, exc_tb)