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Filename : unpacking.py
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"""Utilities related archives."""

import logging
import os
import shutil
import stat
import sys
import tarfile
import zipfile
from typing import Iterable, List, Optional
from zipfile import ZipInfo

from pip._internal.exceptions import InstallationError
from pip._internal.utils.filetypes import (
    BZ2_EXTENSIONS,
    TAR_EXTENSIONS,
    XZ_EXTENSIONS,
    ZIP_EXTENSIONS,
)
from pip._internal.utils.misc import ensure_dir

logger = logging.getLogger(__name__)


SUPPORTED_EXTENSIONS = ZIP_EXTENSIONS + TAR_EXTENSIONS

try:
    import bz2  # noqa

    SUPPORTED_EXTENSIONS += BZ2_EXTENSIONS
except ImportError:
    logger.debug("bz2 module is not available")

try:
    # Only for Python 3.3+
    import lzma  # noqa

    SUPPORTED_EXTENSIONS += XZ_EXTENSIONS
except ImportError:
    logger.debug("lzma module is not available")


def current_umask() -> int:
    """Get the current umask which involves having to set it temporarily."""
    mask = os.umask(0)
    os.umask(mask)
    return mask


def split_leading_dir(path: str) -> List[str]:
    path = path.lstrip("/").lstrip("\\")
    if "/" in path and (
        ("\\" in path and path.find("/") < path.find("\\")) or "\\" not in path
    ):
        return path.split("/", 1)
    elif "\\" in path:
        return path.split("\\", 1)
    else:
        return [path, ""]


def has_leading_dir(paths: Iterable[str]) -> bool:
    """Returns true if all the paths have the same leading path name
    (i.e., everything is in one subdirectory in an archive)"""
    common_prefix = None
    for path in paths:
        prefix, rest = split_leading_dir(path)
        if not prefix:
            return False
        elif common_prefix is None:
            common_prefix = prefix
        elif prefix != common_prefix:
            return False
    return True


def is_within_directory(directory: str, target: str) -> bool:
    """
    Return true if the absolute path of target is within the directory
    """
    abs_directory = os.path.abspath(directory)
    abs_target = os.path.abspath(target)

    prefix = os.path.commonprefix([abs_directory, abs_target])
    return prefix == abs_directory


def _get_default_mode_plus_executable() -> int:
    return 0o777 & ~current_umask() | 0o111


def set_extracted_file_to_default_mode_plus_executable(path: str) -> None:
    """
    Make file present at path have execute for user/group/world
    (chmod +x) is no-op on windows per python docs
    """
    os.chmod(path, _get_default_mode_plus_executable())


def zip_item_is_executable(info: ZipInfo) -> bool:
    mode = info.external_attr >> 16
    # if mode and regular file and any execute permissions for
    # user/group/world?
    return bool(mode and stat.S_ISREG(mode) and mode & 0o111)


def unzip_file(filename: str, location: str, flatten: bool = True) -> None:
    """
    Unzip the file (with path `filename`) to the destination `location`.  All
    files are written based on system defaults and umask (i.e. permissions are
    not preserved), except that regular file members with any execute
    permissions (user, group, or world) have "chmod +x" applied after being
    written. Note that for windows, any execute changes using os.chmod are
    no-ops per the python docs.
    """
    ensure_dir(location)
    zipfp = open(filename, "rb")
    try:
        zip = zipfile.ZipFile(zipfp, allowZip64=True)
        leading = has_leading_dir(zip.namelist()) and flatten
        for info in zip.infolist():
            name = info.filename
            fn = name
            if leading:
                fn = split_leading_dir(name)[1]
            fn = os.path.join(location, fn)
            dir = os.path.dirname(fn)
            if not is_within_directory(location, fn):
                message = (
                    "The zip file ({}) has a file ({}) trying to install "
                    "outside target directory ({})"
                )
                raise InstallationError(message.format(filename, fn, location))
            if fn.endswith("/") or fn.endswith("\\"):
                # A directory
                ensure_dir(fn)
            else:
                ensure_dir(dir)
                # Don't use read() to avoid allocating an arbitrarily large
                # chunk of memory for the file's content
                fp = zip.open(name)
                try:
                    with open(fn, "wb") as destfp:
                        shutil.copyfileobj(fp, destfp)
                finally:
                    fp.close()
                    if zip_item_is_executable(info):
                        set_extracted_file_to_default_mode_plus_executable(fn)
    finally:
        zipfp.close()


def untar_file(filename: str, location: str) -> None:
    """
    Untar the file (with path `filename`) to the destination `location`.
    All files are written based on system defaults and umask (i.e. permissions
    are not preserved), except that regular file members with any execute
    permissions (user, group, or world) have "chmod +x" applied on top of the
    default.  Note that for windows, any execute changes using os.chmod are
    no-ops per the python docs.
    """
    ensure_dir(location)
    if filename.lower().endswith(".gz") or filename.lower().endswith(".tgz"):
        mode = "r:gz"
    elif filename.lower().endswith(BZ2_EXTENSIONS):
        mode = "r:bz2"
    elif filename.lower().endswith(XZ_EXTENSIONS):
        mode = "r:xz"
    elif filename.lower().endswith(".tar"):
        mode = "r"
    else:
        logger.warning(
            "Cannot determine compression type for file %s",
            filename,
        )
        mode = "r:*"

    tar = tarfile.open(filename, mode, encoding="utf-8")  # type: ignore
    try:
        leading = has_leading_dir([member.name for member in tar.getmembers()])

        # PEP 706 added `tarfile.data_filter`, and made some other changes to
        # Python's tarfile module (see below). The features were backported to
        # security releases.
        try:
            data_filter = tarfile.data_filter
        except AttributeError:
            _untar_without_filter(filename, location, tar, leading)
        else:
            default_mode_plus_executable = _get_default_mode_plus_executable()

            if leading:
                # Strip the leading directory from all files in the archive,
                # including hardlink targets (which are relative to the
                # unpack location).
                for member in tar.getmembers():
                    name_lead, name_rest = split_leading_dir(member.name)
                    member.name = name_rest
                    if member.islnk():
                        lnk_lead, lnk_rest = split_leading_dir(member.linkname)
                        if lnk_lead == name_lead:
                            member.linkname = lnk_rest

            def pip_filter(member: tarfile.TarInfo, path: str) -> tarfile.TarInfo:
                orig_mode = member.mode
                try:
                    try:
                        member = data_filter(member, location)
                    except tarfile.LinkOutsideDestinationError:
                        if sys.version_info[:3] in {
                            (3, 9, 17),
                            (3, 10, 12),
                            (3, 11, 4),
                        }:
                            # The tarfile filter in specific Python versions
                            # raises LinkOutsideDestinationError on valid input
                            # (https://github.com/python/cpython/issues/107845)
                            # Ignore the error there, but do use the
                            # more lax `tar_filter`
                            member = tarfile.tar_filter(member, location)
                        else:
                            raise
                except tarfile.TarError as exc:
                    message = "Invalid member in the tar file {}: {}"
                    # Filter error messages mention the member name.
                    # No need to add it here.
                    raise InstallationError(
                        message.format(
                            filename,
                            exc,
                        )
                    )
                if member.isfile() and orig_mode & 0o111:
                    member.mode = default_mode_plus_executable
                else:
                    # See PEP 706 note above.
                    # The PEP changed this from `int` to `Optional[int]`,
                    # where None means "use the default". Mypy doesn't
                    # know this yet.
                    member.mode = None  # type: ignore [assignment]
                return member

            tar.extractall(location, filter=pip_filter)

    finally:
        tar.close()


def _untar_without_filter(
    filename: str,
    location: str,
    tar: tarfile.TarFile,
    leading: bool,
) -> None:
    """Fallback for Python without tarfile.data_filter"""
    for member in tar.getmembers():
        fn = member.name
        if leading:
            fn = split_leading_dir(fn)[1]
        path = os.path.join(location, fn)
        if not is_within_directory(location, path):
            message = (
                "The tar file ({}) has a file ({}) trying to install "
                "outside target directory ({})"
            )
            raise InstallationError(message.format(filename, path, location))
        if member.isdir():
            ensure_dir(path)
        elif member.issym():
            try:
                tar._extract_member(member, path)
            except Exception as exc:
                # Some corrupt tar files seem to produce this
                # (specifically bad symlinks)
                logger.warning(
                    "In the tar file %s the member %s is invalid: %s",
                    filename,
                    member.name,
                    exc,
                )
                continue
        else:
            try:
                fp = tar.extractfile(member)
            except (KeyError, AttributeError) as exc:
                # Some corrupt tar files seem to produce this
                # (specifically bad symlinks)
                logger.warning(
                    "In the tar file %s the member %s is invalid: %s",
                    filename,
                    member.name,
                    exc,
                )
                continue
            ensure_dir(os.path.dirname(path))
            assert fp is not None
            with open(path, "wb") as destfp:
                shutil.copyfileobj(fp, destfp)
            fp.close()
            # Update the timestamp (useful for cython compiled files)
            tar.utime(member, path)
            # member have any execute permissions for user/group/world?
            if member.mode & 0o111:
                set_extracted_file_to_default_mode_plus_executable(path)


def unpack_file(
    filename: str,
    location: str,
    content_type: Optional[str] = None,
) -> None:
    filename = os.path.realpath(filename)
    if (
        content_type == "application/zip"
        or filename.lower().endswith(ZIP_EXTENSIONS)
        or zipfile.is_zipfile(filename)
    ):
        unzip_file(filename, location, flatten=not filename.endswith(".whl"))
    elif (
        content_type == "application/x-gzip"
        or tarfile.is_tarfile(filename)
        or filename.lower().endswith(TAR_EXTENSIONS + BZ2_EXTENSIONS + XZ_EXTENSIONS)
    ):
        untar_file(filename, location)
    else:
        # FIXME: handle?
        # FIXME: magic signatures?
        logger.critical(
            "Cannot unpack file %s (downloaded from %s, content-type: %s); "
            "cannot detect archive format",
            filename,
            location,
            content_type,
        )
        raise InstallationError(f"Cannot determine archive format of {location}")