python/py313/Lib/site-packages/py7zr/helpers.py

#!/usr/bin/python -u
#
# p7zr library
#
# Copyright (c) 2019-2024 Hiroshi Miura <miurahr@linux.com>
# Copyright (c) 2004-2015 by Joachim Bauch, mail@joachim-bauch.de
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
#
from __future__ import annotations

import ctypes
import hashlib
import os
import pathlib
import platform
import posixpath
import sys
import time as _time
import zlib
from datetime import datetime, timedelta, timezone, tzinfo
from typing import TYPE_CHECKING

from py7zr import Bad7zFile
from py7zr.win32compat import is_windows_native_python, is_windows_unc_path

if TYPE_CHECKING:
    from typing_extensions import Self

# String used at the beginning of relative paths
RELATIVE_PATH_MARKER = "./"


def calculate_crc32(data: bytes, value: int = 0, blocksize: int = 1024 * 1024) -> int:
    """Calculate CRC32 of strings with arbitrary lengths."""
    if len(data) <= blocksize:
        value = zlib.crc32(data, value)
    else:
        length = len(data)
        pos = blocksize
        value = zlib.crc32(data[:pos], value)
        while pos < length:
            value = zlib.crc32(data[pos : pos + blocksize], value)
            pos += blocksize
    return value & 0xFFFFFFFF


def _get_hash(digest: str):
    if digest not in hashlib.algorithms_available:
        raise ValueError("Unknown digest method for password protection.")
    if digest == "sha256":
        return hashlib.sha256()
    return hashlib.new(digest)


def _calculate_key1(password: bytes, cycles: int, salt: bytes, digest: str) -> bytes:
    """Calculate 7zip AES encryption key. Base implementation."""
    assert cycles <= 0x3F
    if cycles == 0x3F:
        ba = bytearray(salt + password + bytes(32))
        key: bytes = bytes(ba[:32])
    else:
        rounds = 1 << cycles
        m = _get_hash(digest)
        for round in range(rounds):
            m.update(salt + password + round.to_bytes(8, byteorder="little", signed=False))
        key = m.digest()[:32]
    return key


def _calculate_key2(password: bytes, cycles: int, salt: bytes, digest: str):
    """Calculate 7zip AES encryption key.
    It uses ctypes and memoryview buffer and zero-copy technology on Python."""
    assert cycles <= 0x3F
    if cycles == 0x3F:
        key: bytes = bytes(bytearray(salt + password + bytes(32))[:32])
    else:
        rounds = 1 << cycles
        m = _get_hash(digest)
        length = len(salt) + len(password)

        class RoundBuf(ctypes.LittleEndianStructure):
            _pack_ = 1
            _fields_ = [
                ("saltpassword", ctypes.c_ubyte * length),
                ("round", ctypes.c_uint64),
            ]

        buf = RoundBuf()
        for i, c in enumerate(salt + password):
            buf.saltpassword[i] = c
        buf.round = 0
        mv = memoryview(buf)
        while buf.round < rounds:
            m.update(mv)
            buf.round += 1
        key = m.digest()[:32]
    return key


def _calculate_key3(password: bytes, cycles: int, salt: bytes, digest: str) -> bytes:
    """Calculate 7zip AES encryption key.
    Concat values in order to reduce number of calls of Hash.update()."""
    assert cycles <= 0x3F
    if cycles == 0x3F:
        ba = bytearray(salt + password + bytes(32))
        key: bytes = bytes(ba[:32])
    else:
        cat_cycle = 6
        if cycles > cat_cycle:
            rounds = 1 << cat_cycle
            stages = 1 << (cycles - cat_cycle)
        else:
            rounds = 1 << cycles
            stages = 1 << 0
        m = _get_hash(digest)
        saltpassword = salt + password
        s = 0  # type: int  # (0..stages) * rounds
        if platform.python_implementation() == "PyPy":
            for _ in range(stages):
                m.update(
                    memoryview(
                        b"".join(
                            [saltpassword + (s + i).to_bytes(8, byteorder="little", signed=False) for i in range(rounds)]
                        )
                    )
                )
                s += rounds
        else:
            for _ in range(stages):
                m.update(
                    b"".join([saltpassword + (s + i).to_bytes(8, byteorder="little", signed=False) for i in range(rounds)])
                )
                s += rounds
        key = m.digest()[:32]

    return key


if platform.python_implementation() == "PyPy" or sys.version_info > (3, 6):
    calculate_key = _calculate_key3
else:
    calculate_key = _calculate_key2  # it is faster when CPython 3.6.x


def filetime_to_dt(ft):
    """Convert Windows NTFS file time into python datetime object."""
    EPOCH_AS_FILETIME = 116444736000000000
    us = (ft - EPOCH_AS_FILETIME) // 10
    return datetime(1970, 1, 1, tzinfo=timezone.utc) + timedelta(microseconds=us)


ZERO = timedelta(0)
HOUR = timedelta(hours=1)
SECOND = timedelta(seconds=1)

# A class capturing the platform's idea of local time.
# (May result in wrong values on historical times in
#  timezones where UTC offset and/or the DST rules had
#  changed in the past.)

STDOFFSET = timedelta(seconds=-_time.timezone)
if _time.daylight:
    DSTOFFSET = timedelta(seconds=-_time.altzone)
else:
    DSTOFFSET = STDOFFSET

DSTDIFF = DSTOFFSET - STDOFFSET


class LocalTimezone(tzinfo):
    def fromutc(self, dt):
        assert dt.tzinfo is self
        stamp = (dt - datetime(1970, 1, 1, tzinfo=self)) // SECOND
        args = _time.localtime(stamp)[:6]
        # dst_diff = DSTDIFF // SECOND
        # Detect fold
        # fold = args == _time.localtime(stamp - dst_diff)
        return datetime(*args, microsecond=dt.microsecond, tzinfo=self)

    def utcoffset(self, dt):
        if self._isdst(dt):
            return DSTOFFSET
        else:
            return STDOFFSET

    def dst(self, dt):
        if self._isdst(dt):
            return DSTDIFF
        else:
            return ZERO

    def tzname(self, dt):
        return _time.tzname[self._isdst(dt)]

    def _isdst(self, dt):
        tt = (
            dt.year,
            dt.month,
            dt.day,
            dt.hour,
            dt.minute,
            dt.second,
            dt.weekday(),
            0,
            0,
        )
        stamp = _time.mktime(tt)
        tt = _time.localtime(stamp)
        return tt.tm_isdst > 0


Local = LocalTimezone()
TIMESTAMP_ADJUST = -11644473600


class UTC(tzinfo):
    """UTC"""

    def utcoffset(self, dt):
        return ZERO

    def tzname(self, dt):
        return "UTC"

    def dst(self, dt):
        return ZERO

    def _call__(self):
        return self


class ArchiveTimestamp(int):
    """Windows FILETIME timestamp."""

    def __repr__(self):
        return f"{type(self).__name__}({self})"

    def __index__(self):
        return self.__int__()

    def totimestamp(self) -> float:
        """Convert 7z FILETIME to Python timestamp."""
        # FILETIME is 100-nanosecond intervals since 1601/01/01 (UTC)
        return (self / 10000000.0) + TIMESTAMP_ADJUST

    def as_datetime(self) -> datetime:
        """Convert FILETIME to Python datetime object."""
        return datetime.fromtimestamp(self.totimestamp(), UTC())

    @classmethod
    def from_datetime(cls, val: float | int) -> Self:
        return cls((val - TIMESTAMP_ADJUST) * 10000000.0)

    @classmethod
    def from_now(cls) -> Self:
        return cls((_time.time() - TIMESTAMP_ADJUST) * 10000000.0)


def islink(path: str | pathlib.Path) -> bool:
    """
    Cross-platform islink implementation.
    Support Windows NT symbolic links and reparse points.
    """
    return os.path.islink(path)


def readlink(path: str | pathlib.Path, *, dir_fd=None) -> str | pathlib.Path:
    """
    Cross-platform compat implementation of os.readlink and Path.readlink().
    Support Windows NT symbolic links and reparse points.
    When called with path argument as pathlike(str), return result as a pathlike(str).
    When called with Path object, return also Path object.
    When called with path argument as bytes, return result as a bytes.
    """
    if not os.path.exists(str(path)):
        raise OSError(22, "Invalid argument", path)

    if isinstance(path, pathlib.Path) and dir_fd is None:
        return path.readlink()
    else:
        return os.readlink(path, dir_fd=dir_fd)


def remove_relative_path_marker(path: str) -> str:
    """
    Removes './' from the beginning of a path-like string
    """
    processed_path = path

    if path.startswith(RELATIVE_PATH_MARKER):
        processed_path = path[len(RELATIVE_PATH_MARKER) :]

    return processed_path


def remove_trailing_slash(path: str) -> str:
    """
    Removes '/' from the end of a path-like string
    """
    if path.endswith(posixpath.sep):
        return path[:-1]
    return path


def canonical_path(target: pathlib.Path) -> pathlib.Path:
    """Return a canonical path of target argument."""
    stack: list[str] = []
    for p in target.parts:
        if p != ".." or len(stack) == 0:
            stack.append(p)
            continue
        # treat '..'
        if stack[-1] == "..":
            stack.append(p)  # '../' + '../' -> '../../'
        elif stack[-1] == "/":
            pass  # '/' + '../' -> '/'
        else:
            stack.pop()  # 'foo/boo/' + '..' -> 'foo/'
    return pathlib.Path(*stack)


def is_relative_to(my: pathlib.Path, *other) -> bool:
    """Return True when path is relative to other path, otherwise False."""
    try:
        my.relative_to(canonical_path(*other))
    except ValueError:
        return False
    return True


def get_sanitized_output_path(fname: str, path: pathlib.Path | None) -> pathlib.Path:
    """
    check f.filename has invalid directory traversals
    When condition is not satisfied, raise Bad7zFile
    """
    if fname.startswith("/"):
        fname = fname.lstrip("/")

    if path is None:
        target_path = canonical_path(pathlib.Path.cwd().joinpath(fname))
        if is_relative_to(target_path, pathlib.Path.cwd()):
            return pathlib.Path(remove_relative_path_marker(fname))
    else:
        outfile = canonical_path(path.joinpath(remove_relative_path_marker(fname)))
        if is_relative_to(outfile, path):
            return pathlib.Path(outfile)
    raise Bad7zFile(f"Specified path is bad: {fname}")


def check_archive_path(arcname: str) -> bool:
    """
    Check arcname argument is valid for archive.
    It should not be absolute, if so it returns False.
    It should not be evil traversal attack path.
    Otherwise, returns True.
    """
    if pathlib.Path(arcname).is_absolute():
        return False
    # test against dummy parent path
    if sys.platform == "win32":
        path = pathlib.Path("C:/foo/boo/fuga/hoge/a90sufoiasj09/dafj08sajfa/")
    else:
        path = pathlib.Path("/foo/boo/fuga/hoge/a90sufoiasj09/dafj08sajfa/")
    return is_path_valid(path.joinpath(arcname), path)


def is_path_valid(target: pathlib.Path, parent: pathlib.Path) -> bool:
    """
    Check if target path is valid against parent path.
    It returns False when target path has '..' and point out of parent path.
    Otherwise, returns True.
    """
    if parent.is_absolute():
        return is_relative_to(canonical_path(target), parent)
    else:
        return is_relative_to(canonical_path(target), pathlib.Path.cwd().joinpath(parent))


def check_win32_file_namespace(pathname: pathlib.Path) -> pathlib.Path:
    # When python on Windows and not python on Cygwin,
    # Add win32 file namespace to exceed Microsoft Windows
    # path length limitation to 260 bytes
    # ref.
    # https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file
    # In editions of Windows before Windows 10 version 1607,
    # the maximum length for a path is MAX_PATH, which is defined as
    # 260 characters. In later versions of Windows, changing a registry key
    # or select option when python installation is required to remove the limit.
    if is_windows_native_python() and pathname.is_absolute() and not is_windows_unc_path(pathname):
        pathname = pathlib.WindowsPath("\\\\?\\" + str(pathname))
    return pathname