_compat.py

import codecs
import io
import os
import re
import sys
import typing as t
from weakref import WeakKeyDictionary

CYGWIN = sys.platform.startswith("cygwin")
WIN = sys.platform.startswith("win")
auto_wrap_for_ansi: t.Optional[t.Callable[[t.TextIO], t.TextIO]] = None
_ansi_re = re.compile(r"\033\[[;?0-9]*[a-zA-Z]")


def _make_text_stream(
    stream: t.BinaryIO,
    encoding: t.Optional[str],
    errors: t.Optional[str],
    force_readable: bool = False,
    force_writable: bool = False,
) -> t.TextIO:
    if encoding is None:
        encoding = get_best_encoding(stream)
    if errors is None:
        errors = "replace"
    return _NonClosingTextIOWrapper(
        stream,
        encoding,
        errors,
        line_buffering=True,
        force_readable=force_readable,
        force_writable=force_writable,
    )


def is_ascii_encoding(encoding: str) -> bool:
    """Checks if a given encoding is ascii."""
    try:
        return codecs.lookup(encoding).name == "ascii"
    except LookupError:
        return False


def get_best_encoding(stream: t.IO[t.Any]) -> str:
    """Returns the default stream encoding if not found."""
    rv = getattr(stream, "encoding", None) or sys.getdefaultencoding()
    if is_ascii_encoding(rv):
        return "utf-8"
    return rv


class _NonClosingTextIOWrapper(io.TextIOWrapper):
    def __init__(
        self,
        stream: t.BinaryIO,
        encoding: t.Optional[str],
        errors: t.Optional[str],
        force_readable: bool = False,
        force_writable: bool = False,
        **extra: t.Any,
    ) -> None:
        self._stream = stream = t.cast(
            t.BinaryIO, _FixupStream(stream, force_readable, force_writable)
        )
        super().__init__(stream, encoding, errors, **extra)

    def __del__(self) -> None:
        try:
            self.detach()
        except Exception:
            pass

    def isatty(self) -> bool:
        # https://bitbucket.org/pypy/pypy/issue/1803
        return self._stream.isatty()


class _FixupStream:
    """The new io interface needs more from streams than streams
    traditionally implement.  As such, this fix-up code is necessary in
    some circumstances.

    The forcing of readable and writable flags are there because some tools
    put badly patched objects on sys (one such offender are certain version
    of jupyter notebook).
    """

    def __init__(
        self,
        stream: t.BinaryIO,
        force_readable: bool = False,
        force_writable: bool = False,
    ):
        self._stream = stream
        self._force_readable = force_readable
        self._force_writable = force_writable

    def __getattr__(self, name: str) -> t.Any:
        return getattr(self._stream, name)

    def read1(self, size: int) -> bytes:
        f = getattr(self._stream, "read1", None)

        if f is not None:
            return t.cast(bytes, f(size))

        return self._stream.read(size)

    def readable(self) -> bool:
        if self._force_readable:
            return True
        x = getattr(self._stream, "readable", None)
        if x is not None:
            return t.cast(bool, x())
        try:
            self._stream.read(0)
        except Exception:
            return False
        return True

    def writable(self) -> bool:
        if self._force_writable:
            return True
        x = getattr(self._stream, "writable", None)
        if x is not None:
            return t.cast(bool, x())
        try:
            self._stream.write("")  # type: ignore
        except Exception:
            try:
                self._stream.write(b"")
            except Exception:
                return False
        return True

    def seekable(self) -> bool:
        x = getattr(self._stream, "seekable", None)
        if x is not None:
            return t.cast(bool, x())
        try:
            self._stream.seek(self._stream.tell())
        except Exception:
            return False
        return True


def _is_binary_reader(stream: t.IO[t.Any], default: bool = False) -> bool:
    try:
        return isinstance(stream.read(0), bytes)
    except Exception:
        return default
        # This happens in some cases where the stream was already
        # closed.  In this case, we assume the default.


def _is_binary_writer(stream: t.IO[t.Any], default: bool = False) -> bool:
    try:
        stream.write(b"")
    except Exception:
        try:
            stream.write("")
            return False
        except Exception:
            pass
        return default
    return True


def _find_binary_reader(stream: t.IO[t.Any]) -> t.Optional[t.BinaryIO]:
    # We need to figure out if the given stream is already binary.
    # This can happen because the official docs recommend detaching
    # the streams to get binary streams.  Some code might do this, so
    # we need to deal with this case explicitly.
    if _is_binary_reader(stream, False):
        return t.cast(t.BinaryIO, stream)

    buf = getattr(stream, "buffer", None)

    # Same situation here; this time we assume that the buffer is
    # actually binary in case it's closed.
    if buf is not None and _is_binary_reader(buf, True):
        return t.cast(t.BinaryIO, buf)

    return None


def _find_binary_writer(stream: t.IO[t.Any]) -> t.Optional[t.BinaryIO]:
    # We need to figure out if the given stream is already binary.
    # This can happen because the official docs recommend detaching
    # the streams to get binary streams.  Some code might do this, so
    # we need to deal with this case explicitly.
    if _is_binary_writer(stream, False):
        return t.cast(t.BinaryIO, stream)

    buf = getattr(stream, "buffer", None)

    # Same situation here; this time we assume that the buffer is
    # actually binary in case it's closed.
    if buf is not None and _is_binary_writer(buf, True):
        return t.cast(t.BinaryIO, buf)

    return None


def _stream_is_misconfigured(stream: t.TextIO) -> bool:
    """A stream is misconfigured if its encoding is ASCII."""
    # If the stream does not have an encoding set, we assume it's set
    # to ASCII.  This appears to happen in certain unittest
    # environments.  It's not quite clear what the correct behavior is
    # but this at least will force Click to recover somehow.
    return is_ascii_encoding(getattr(stream, "encoding", None) or "ascii")


def _is_compat_stream_attr(stream: t.TextIO, attr: str, value: t.Optional[str]) -> bool:
    """A stream attribute is compatible if it is equal to the
    desired value or the desired value is unset and the attribute
    has a value.
    """
    stream_value = getattr(stream, attr, None)
    return stream_value == value or (value is None and stream_value is not None)


def _is_compatible_text_stream(
    stream: t.TextIO, encoding: t.Optional[str], errors: t.Optional[str]
) -> bool:
    """Check if a stream's encoding and errors attributes are
    compatible with the desired values.
    """
    return _is_compat_stream_attr(
        stream, "encoding", encoding
    ) and _is_compat_stream_attr(stream, "errors", errors)


def _force_correct_text_stream(
    text_stream: t.IO[t.Any],
    encoding: t.Optional[str],
    errors: t.Optional[str],
    is_binary: t.Callable[[t.IO[t.Any], bool], bool],
    find_binary: t.Callable[[t.IO[t.Any]], t.Optional[t.BinaryIO]],
    force_readable: bool = False,
    force_writable: bool = False,
) -> t.TextIO:
    if is_binary(text_stream, False):
        binary_reader = t.cast(t.BinaryIO, text_stream)
    else:
        text_stream = t.cast(t.TextIO, text_stream)
        # If the stream looks compatible, and won't default to a
        # misconfigured ascii encoding, return it as-is.
        if _is_compatible_text_stream(text_stream, encoding, errors) and not (
            encoding is None and _stream_is_misconfigured(text_stream)
        ):
            return text_stream

        # Otherwise, get the underlying binary reader.
        possible_binary_reader = find_binary(text_stream)

        # If that's not possible, silently use the original reader
        # and get mojibake instead of exceptions.
        if possible_binary_reader is None:
            return text_stream

        binary_reader = possible_binary_reader

    # Default errors to replace instead of strict in order to get
    # something that works.
    if errors is None:
        errors = "replace"

    # Wrap the binary stream in a text stream with the correct
    # encoding parameters.
    return _make_text_stream(
        binary_reader,
        encoding,
        errors,
        force_readable=force_readable,
        force_writable=force_writable,
    )


def _force_correct_text_reader(
    text_reader: t.IO[t.Any],
    encoding: t.Optional[str],
    errors: t.Optional[str],
    force_readable: bool = False,
) -> t.TextIO:
    return _force_correct_text_stream(
        text_reader,
        encoding,
        errors,
        _is_binary_reader,
        _find_binary_reader,
        force_readable=force_readable,
    )


def _force_correct_text_writer(
    text_writer: t.IO[t.Any],
    encoding: t.Optional[str],
    errors: t.Optional[str],
    force_writable: bool = False,
) -> t.TextIO:
    return _force_correct_text_stream(
        text_writer,
        encoding,
        errors,
        _is_binary_writer,
        _find_binary_writer,
        force_writable=force_writable,
    )


def get_binary_stdin() -> t.BinaryIO:
    reader = _find_binary_reader(sys.stdin)
    if reader is None:
        raise RuntimeError("Was not able to determine binary stream for sys.stdin.")
    return reader


def get_binary_stdout() -> t.BinaryIO:
    writer = _find_binary_writer(sys.stdout)
    if writer is None:
        raise RuntimeError("Was not able to determine binary stream for sys.stdout.")
    return writer


def get_binary_stderr() -> t.BinaryIO:
    writer = _find_binary_writer(sys.stderr)
    if writer is None:
        raise RuntimeError("Was not able to determine binary stream for sys.stderr.")
    return writer


def get_text_stdin(
    encoding: t.Optional[str] = None, errors: t.Optional[str] = None
) -> t.TextIO:
    rv = _get_windows_console_stream(sys.stdin, encoding, errors)
    if rv is not None:
        return rv
    return _force_correct_text_reader(sys.stdin, encoding, errors, force_readable=True)


def get_text_stdout(
    encoding: t.Optional[str] = None, errors: t.Optional[str] = None
) -> t.TextIO:
    rv = _get_windows_console_stream(sys.stdout, encoding, errors)
    if rv is not None:
        return rv
    return _force_correct_text_writer(sys.stdout, encoding, errors, force_writable=True)


def get_text_stderr(
    encoding: t.Optional[str] = None, errors: t.Optional[str] = None
) -> t.TextIO:
    rv = _get_windows_console_stream(sys.stderr, encoding, errors)
    if rv is not None:
        return rv
    return _force_correct_text_writer(sys.stderr, encoding, errors, force_writable=True)


def _wrap_io_open(
    file: t.Union[str, "os.PathLike[str]", int],
    mode: str,
    encoding: t.Optional[str],
    errors: t.Optional[str],
) -> t.IO[t.Any]:
    """Handles not passing ``encoding`` and ``errors`` in binary mode."""
    if "b" in mode:
        return open(file, mode)

    return open(file, mode, encoding=encoding, errors=errors)


def open_stream(
    filename: "t.Union[str, os.PathLike[str]]",
    mode: str = "r",
    encoding: t.Optional[str] = None,
    errors: t.Optional[str] = "strict",
    atomic: bool = False,
) -> t.Tuple[t.IO[t.Any], bool]:
    binary = "b" in mode
    filename = os.fspath(filename)

    # Standard streams first. These are simple because they ignore the
    # atomic flag. Use fsdecode to handle Path("-").
    if os.fsdecode(filename) == "-":
        if any(m in mode for m in ["w", "a", "x"]):
            if binary:
                return get_binary_stdout(), False
            return get_text_stdout(encoding=encoding, errors=errors), False
        if binary:
            return get_binary_stdin(), False
        return get_text_stdin(encoding=encoding, errors=errors), False

    # Non-atomic writes directly go out through the regular open functions.
    if not atomic:
        return _wrap_io_open(filename, mode, encoding, errors), True

    # Some usability stuff for atomic writes
    if "a" in mode:
        raise ValueError(
            "Appending to an existing file is not supported, because that"
            " would involve an expensive `copy`-operation to a temporary"
            " file. Open the file in normal `w`-mode and copy explicitly"
            " if that's what you're after."
        )
    if "x" in mode:
        raise ValueError("Use the `overwrite`-parameter instead.")
    if "w" not in mode:
        raise ValueError("Atomic writes only make sense with `w`-mode.")

    # Atomic writes are more complicated.  They work by opening a file
    # as a proxy in the same folder and then using the fdopen
    # functionality to wrap it in a Python file.  Then we wrap it in an
    # atomic file that moves the file over on close.
    import errno
    import random

    try:
        perm: t.Optional[int] = os.stat(filename).st_mode
    except OSError:
        perm = None

    flags = os.O_RDWR | os.O_CREAT | os.O_EXCL

    if binary:
        flags |= getattr(os, "O_BINARY", 0)

    while True:
        tmp_filename = os.path.join(
            os.path.dirname(filename),
            f".__atomic-write{random.randrange(1 << 32):08x}",
        )
        try:
            fd = os.open(tmp_filename, flags, 0o666 if perm is None else perm)
            break
        except OSError as e:
            if e.errno == errno.EEXIST or (
                os.name == "nt"
                and e.errno == errno.EACCES
                and os.path.isdir(e.filename)
                and os.access(e.filename, os.W_OK)
            ):
                continue
            raise

    if perm is not None:
        os.chmod(tmp_filename, perm)  # in case perm includes bits in umask

    f = _wrap_io_open(fd, mode, encoding, errors)
    af = _AtomicFile(f, tmp_filename, os.path.realpath(filename))
    return t.cast(t.IO[t.Any], af), True


class _AtomicFile:
    def __init__(self, f: t.IO[t.Any], tmp_filename: str, real_filename: str) -> None:
        self._f = f
        self._tmp_filename = tmp_filename
        self._real_filename = real_filename
        self.closed = False

    @property
    def name(self) -> str:
        return self._real_filename

    def close(self, delete: bool = False) -> None:
        if self.closed:
            return
        self._f.close()
        os.replace(self._tmp_filename, self._real_filename)
        self.closed = True

    def __getattr__(self, name: str) -> t.Any:
        return getattr(self._f, name)

    def __enter__(self) -> "_AtomicFile":
        return self

    def __exit__(self, exc_type: t.Optional[t.Type[BaseException]], *_: t.Any) -> None:
        self.close(delete=exc_type is not None)

    def __repr__(self) -> str:
        return repr(self._f)


def strip_ansi(value: str) -> str:
    return _ansi_re.sub("", value)


def _is_jupyter_kernel_output(stream: t.IO[t.Any]) -> bool:
    while isinstance(stream, (_FixupStream, _NonClosingTextIOWrapper)):
        stream = stream._stream

    return stream.__class__.__module__.startswith("ipykernel.")


def should_strip_ansi(
    stream: t.Optional[t.IO[t.Any]] = None, color: t.Optional[bool] = None
) -> bool:
    if color is None:
        if stream is None:
            stream = sys.stdin
        return not isatty(stream) and not _is_jupyter_kernel_output(stream)
    return not color


# On Windows, wrap the output streams with colorama to support ANSI
# color codes.
# NOTE: double check is needed so mypy does not analyze this on Linux
if sys.platform.startswith("win") and WIN:
    from ._winconsole import _get_windows_console_stream

    def _get_argv_encoding() -> str:
        import locale

        return locale.getpreferredencoding()

    _ansi_stream_wrappers: t.MutableMapping[t.TextIO, t.TextIO] = WeakKeyDictionary()

    def auto_wrap_for_ansi(  # noqa: F811
        stream: t.TextIO, color: t.Optional[bool] = None
    ) -> t.TextIO:
        """Support ANSI color and style codes on Windows by wrapping a
        stream with colorama.
        """
        try:
            cached = _ansi_stream_wrappers.get(stream)
        except Exception:
            cached = None

        if cached is not None:
            return cached

        import colorama

        strip = should_strip_ansi(stream, color)
        ansi_wrapper = colorama.AnsiToWin32(stream, strip=strip)
        rv = t.cast(t.TextIO, ansi_wrapper.stream)
        _write = rv.write

        def _safe_write(s):
            try:
                return _write(s)
            except BaseException:
                ansi_wrapper.reset_all()
                raise

        rv.write = _safe_write

        try:
            _ansi_stream_wrappers[stream] = rv
        except Exception:
            pass

        return rv

else:

    def _get_argv_encoding() -> str:
        return getattr(sys.stdin, "encoding", None) or sys.getfilesystemencoding()

    def _get_windows_console_stream(
        f: t.TextIO, encoding: t.Optional[str], errors: t.Optional[str]
    ) -> t.Optional[t.TextIO]:
        return None


def term_len(x: str) -> int:
    return len(strip_ansi(x))


def isatty(stream: t.IO[t.Any]) -> bool:
    try:
        return stream.isatty()
    except Exception:
        return False


def _make_cached_stream_func(
    src_func: t.Callable[[], t.Optional[t.TextIO]],
    wrapper_func: t.Callable[[], t.TextIO],
) -> t.Callable[[], t.Optional[t.TextIO]]:
    cache: t.MutableMapping[t.TextIO, t.TextIO] = WeakKeyDictionary()

    def func() -> t.Optional[t.TextIO]:
        stream = src_func()

        if stream is None:
            return None

        try:
            rv = cache.get(stream)
        except Exception:
            rv = None
        if rv is not None:
            return rv
        rv = wrapper_func()
        try:
            cache[stream] = rv
        except Exception:
            pass
        return rv

    return func


_default_text_stdin = _make_cached_stream_func(lambda: sys.stdin, get_text_stdin)
_default_text_stdout = _make_cached_stream_func(lambda: sys.stdout, get_text_stdout)
_default_text_stderr = _make_cached_stream_func(lambda: sys.stderr, get_text_stderr)


binary_streams: t.Mapping[str, t.Callable[[], t.BinaryIO]] = {
    "stdin": get_binary_stdin,
    "stdout": get_binary_stdout,
    "stderr": get_binary_stderr,
}

text_streams: t.Mapping[
    str, t.Callable[[t.Optional[str], t.Optional[str]], t.TextIO]
] = {
    "stdin": get_text_stdin,
    "stdout": get_text_stdout,
    "stderr": get_text_stderr,
}