Lib/zipfile.py

"""
Read and write ZIP files.

XXX references to utf-8 need further investigation.
"""
import io
import os
import re
import imp
import sys
import time
import stat
import shutil
import struct
import binascii


try:
    import zlib # We may need its compression method
    crc32 = zlib.crc32
except ImportError:
    zlib = None
    crc32 = binascii.crc32

__all__ = ["BadZipfile", "error", "ZIP_STORED", "ZIP_DEFLATED", "is_zipfile",
           "ZipInfo", "ZipFile", "PyZipFile", "LargeZipFile" ]

class BadZipfile(Exception):
    pass


class LargeZipFile(Exception):
    """
    Raised when writing a zipfile, the zipfile requires ZIP64 extensions
    and those extensions are disabled.
    """

error = BadZipfile      # The exception raised by this module

ZIP64_LIMIT = (1 << 31) - 1
ZIP_FILECOUNT_LIMIT = 1 << 16
ZIP_MAX_COMMENT = (1 << 16) - 1

# constants for Zip file compression methods
ZIP_STORED = 0
ZIP_DEFLATED = 8
# Other ZIP compression methods not supported

# Below are some formats and associated data for reading/writing headers using
# the struct module.  The names and structures of headers/records are those used
# in the PKWARE description of the ZIP file format:
#     http://www.pkware.com/documents/casestudies/APPNOTE.TXT
# (URL valid as of January 2008)

# The "end of central directory" structure, magic number, size, and indices
# (section V.I in the format document)
structEndArchive = b"<4s4H2LH"
stringEndArchive = b"PK\005\006"
sizeEndCentDir = struct.calcsize(structEndArchive)

_ECD_SIGNATURE = 0
_ECD_DISK_NUMBER = 1
_ECD_DISK_START = 2
_ECD_ENTRIES_THIS_DISK = 3
_ECD_ENTRIES_TOTAL = 4
_ECD_SIZE = 5
_ECD_OFFSET = 6
_ECD_COMMENT_SIZE = 7
# These last two indices are not part of the structure as defined in the
# spec, but they are used internally by this module as a convenience
_ECD_COMMENT = 8
_ECD_LOCATION = 9

# The "central directory" structure, magic number, size, and indices
# of entries in the structure (section V.F in the format document)
structCentralDir = "<4s4B4HL2L5H2L"
stringCentralDir = b"PK\001\002"
sizeCentralDir = struct.calcsize(structCentralDir)

# indexes of entries in the central directory structure
_CD_SIGNATURE = 0
_CD_CREATE_VERSION = 1
_CD_CREATE_SYSTEM = 2
_CD_EXTRACT_VERSION = 3
_CD_EXTRACT_SYSTEM = 4
_CD_FLAG_BITS = 5
_CD_COMPRESS_TYPE = 6
_CD_TIME = 7
_CD_DATE = 8
_CD_CRC = 9
_CD_COMPRESSED_SIZE = 10
_CD_UNCOMPRESSED_SIZE = 11
_CD_FILENAME_LENGTH = 12
_CD_EXTRA_FIELD_LENGTH = 13
_CD_COMMENT_LENGTH = 14
_CD_DISK_NUMBER_START = 15
_CD_INTERNAL_FILE_ATTRIBUTES = 16
_CD_EXTERNAL_FILE_ATTRIBUTES = 17
_CD_LOCAL_HEADER_OFFSET = 18

# The "local file header" structure, magic number, size, and indices
# (section V.A in the format document)
structFileHeader = "<4s2B4HL2L2H"
stringFileHeader = b"PK\003\004"
sizeFileHeader = struct.calcsize(structFileHeader)

_FH_SIGNATURE = 0
_FH_EXTRACT_VERSION = 1
_FH_EXTRACT_SYSTEM = 2
_FH_GENERAL_PURPOSE_FLAG_BITS = 3
_FH_COMPRESSION_METHOD = 4
_FH_LAST_MOD_TIME = 5
_FH_LAST_MOD_DATE = 6
_FH_CRC = 7
_FH_COMPRESSED_SIZE = 8
_FH_UNCOMPRESSED_SIZE = 9
_FH_FILENAME_LENGTH = 10
_FH_EXTRA_FIELD_LENGTH = 11

# The "Zip64 end of central directory locator" structure, magic number, and size
structEndArchive64Locator = "<4sLQL"
stringEndArchive64Locator = b"PK\x06\x07"
sizeEndCentDir64Locator = struct.calcsize(structEndArchive64Locator)

# The "Zip64 end of central directory" record, magic number, size, and indices
# (section V.G in the format document)
structEndArchive64 = "<4sQ2H2L4Q"
stringEndArchive64 = b"PK\x06\x06"
sizeEndCentDir64 = struct.calcsize(structEndArchive64)

_CD64_SIGNATURE = 0
_CD64_DIRECTORY_RECSIZE = 1
_CD64_CREATE_VERSION = 2
_CD64_EXTRACT_VERSION = 3
_CD64_DISK_NUMBER = 4
_CD64_DISK_NUMBER_START = 5
_CD64_NUMBER_ENTRIES_THIS_DISK = 6
_CD64_NUMBER_ENTRIES_TOTAL = 7
_CD64_DIRECTORY_SIZE = 8
_CD64_OFFSET_START_CENTDIR = 9

def _check_zipfile(fp):
    try:
        if _EndRecData(fp):
            return True         # file has correct magic number
    except IOError:
        pass
    return False

def is_zipfile(filename):
    """Quickly see if a file is a ZIP file by checking the magic number.

    The filename argument may be a file or file-like object too.
    """
    result = False
    try:
        if hasattr(filename, "read"):
            result = _check_zipfile(fp=filename)
        else:
            with open(filename, "rb") as fp:
                result = _check_zipfile(fp)
    except IOError:
        pass
    return result

def _EndRecData64(fpin, offset, endrec):
    """
    Read the ZIP64 end-of-archive records and use that to update endrec
    """
    fpin.seek(offset - sizeEndCentDir64Locator, 2)
    data = fpin.read(sizeEndCentDir64Locator)
    sig, diskno, reloff, disks = struct.unpack(structEndArchive64Locator, data)
    if sig != stringEndArchive64Locator:
        return endrec

    if diskno != 0 or disks != 1:
        raise BadZipfile("zipfiles that span multiple disks are not supported")

    # Assume no 'zip64 extensible data'
    fpin.seek(offset - sizeEndCentDir64Locator - sizeEndCentDir64, 2)
    data = fpin.read(sizeEndCentDir64)
    sig, sz, create_version, read_version, disk_num, disk_dir, \
            dircount, dircount2, dirsize, diroffset = \
            struct.unpack(structEndArchive64, data)
    if sig != stringEndArchive64:
        return endrec

    # Update the original endrec using data from the ZIP64 record
    endrec[_ECD_SIGNATURE] = sig
    endrec[_ECD_DISK_NUMBER] = disk_num
    endrec[_ECD_DISK_START] = disk_dir
    endrec[_ECD_ENTRIES_THIS_DISK] = dircount
    endrec[_ECD_ENTRIES_TOTAL] = dircount2
    endrec[_ECD_SIZE] = dirsize
    endrec[_ECD_OFFSET] = diroffset
    return endrec


def _EndRecData(fpin):
    """Return data from the "End of Central Directory" record, or None.

    The data is a list of the nine items in the ZIP "End of central dir"
    record followed by a tenth item, the file seek offset of this record."""

    # Determine file size
    fpin.seek(0, 2)
    filesize = fpin.tell()

    # Check to see if this is ZIP file with no archive comment (the
    # "end of central directory" structure should be the last item in the
    # file if this is the case).
    try:
        fpin.seek(-sizeEndCentDir, 2)
    except IOError:
        return None
    data = fpin.read()
    if data[0:4] == stringEndArchive and data[-2:] == b"\000\000":
        # the signature is correct and there's no comment, unpack structure
        endrec = struct.unpack(structEndArchive, data)
        endrec=list(endrec)

        # Append a blank comment and record start offset
        endrec.append(b"")
        endrec.append(filesize - sizeEndCentDir)

        # Try to read the "Zip64 end of central directory" structure
        return _EndRecData64(fpin, -sizeEndCentDir, endrec)

    # Either this is not a ZIP file, or it is a ZIP file with an archive
    # comment.  Search the end of the file for the "end of central directory"
    # record signature. The comment is the last item in the ZIP file and may be
    # up to 64K long.  It is assumed that the "end of central directory" magic
    # number does not appear in the comment.
    maxCommentStart = max(filesize - (1 << 16) - sizeEndCentDir, 0)
    fpin.seek(maxCommentStart, 0)
    data = fpin.read()
    start = data.rfind(stringEndArchive)
    if start >= 0:
        # found the magic number; attempt to unpack and interpret
        recData = data[start:start+sizeEndCentDir]
        endrec = list(struct.unpack(structEndArchive, recData))
        comment = data[start+sizeEndCentDir:]
        # check that comment length is correct
        if endrec[_ECD_COMMENT_SIZE] == len(comment):
            # Append the archive comment and start offset
            endrec.append(comment)
            endrec.append(maxCommentStart + start)

            # Try to read the "Zip64 end of central directory" structure
            return _EndRecData64(fpin, maxCommentStart + start - filesize,
                                 endrec)

    # Unable to find a valid end of central directory structure
    return


class ZipInfo (object):
    """Class with attributes describing each file in the ZIP archive."""

    __slots__ = (
            'orig_filename',
            'filename',
            'date_time',
            'compress_type',
            'comment',
            'extra',
            'create_system',
            'create_version',
            'extract_version',
            'reserved',
            'flag_bits',
            'volume',
            'internal_attr',
            'external_attr',
            'header_offset',
            'CRC',
            'compress_size',
            'file_size',
            '_raw_time',
        )

    def __init__(self, filename="NoName", date_time=(1980,1,1,0,0,0)):
        self.orig_filename = filename   # Original file name in archive

        # Terminate the file name at the first null byte.  Null bytes in file
        # names are used as tricks by viruses in archives.
        null_byte = filename.find(chr(0))
        if null_byte >= 0:
            filename = filename[0:null_byte]
        # This is used to ensure paths in generated ZIP files always use
        # forward slashes as the directory separator, as required by the
        # ZIP format specification.
        if os.sep != "/" and os.sep in filename:
            filename = filename.replace(os.sep, "/")

        self.filename = filename        # Normalized file name
        self.date_time = date_time      # year, month, day, hour, min, sec
        # Standard values:
        self.compress_type = ZIP_STORED # Type of compression for the file
        self.comment = b""              # Comment for each file
        self.extra = b""                # ZIP extra data
        if sys.platform == 'win32':
            self.create_system = 0          # System which created ZIP archive
        else:
            # Assume everything else is unix-y
            self.create_system = 3          # System which created ZIP archive
        self.create_version = 20        # Version which created ZIP archive
        self.extract_version = 20       # Version needed to extract archive
        self.reserved = 0               # Must be zero
        self.flag_bits = 0              # ZIP flag bits
        self.volume = 0                 # Volume number of file header
        self.internal_attr = 0          # Internal attributes
        self.external_attr = 0          # External file attributes
        # Other attributes are set by class ZipFile:
        # header_offset         Byte offset to the file header
        # CRC                   CRC-32 of the uncompressed file
        # compress_size         Size of the compressed file
        # file_size             Size of the uncompressed file

    def FileHeader(self):
        """Return the per-file header as a string."""
        dt = self.date_time
        dosdate = (dt[0] - 1980) << 9 | dt[1] << 5 | dt[2]
        dostime = dt[3] << 11 | dt[4] << 5 | (dt[5] // 2)
        if self.flag_bits & 0x08:
            # Set these to zero because we write them after the file data
            CRC = compress_size = file_size = 0
        else:
            CRC = self.CRC
            compress_size = self.compress_size
            file_size = self.file_size

        extra = self.extra

        if file_size > ZIP64_LIMIT or compress_size > ZIP64_LIMIT:
            # File is larger than what fits into a 4 byte integer,
            # fall back to the ZIP64 extension
            fmt = '<HHQQ'
            extra = extra + struct.pack(fmt,
                    1, struct.calcsize(fmt)-4, file_size, compress_size)
            file_size = 0xffffffff
            compress_size = 0xffffffff
            self.extract_version = max(45, self.extract_version)
            self.create_version = max(45, self.extract_version)

        filename, flag_bits = self._encodeFilenameFlags()
        header = struct.pack(structFileHeader, stringFileHeader,
                 self.extract_version, self.reserved, flag_bits,
                 self.compress_type, dostime, dosdate, CRC,
                 compress_size, file_size,
                 len(filename), len(extra))
        return header + filename + extra

    def _encodeFilenameFlags(self):
        try:
            return self.filename.encode('ascii'), self.flag_bits
        except UnicodeEncodeError:
            return self.filename.encode('utf-8'), self.flag_bits | 0x800

    def _decodeExtra(self):
        # Try to decode the extra field.
        extra = self.extra
        unpack = struct.unpack
        while extra:
            tp, ln = unpack('<HH', extra[:4])
            if tp == 1:
                if ln >= 24:
                    counts = unpack('<QQQ', extra[4:28])
                elif ln == 16:
                    counts = unpack('<QQ', extra[4:20])
                elif ln == 8:
                    counts = unpack('<Q', extra[4:12])
                elif ln == 0:
                    counts = ()
                else:
                    raise RuntimeError("Corrupt extra field %s"%(ln,))

                idx = 0

                # ZIP64 extension (large files and/or large archives)
                if self.file_size in (0xffffffffffffffff, 0xffffffff):
                    self.file_size = counts[idx]
                    idx += 1

                if self.compress_size == 0xFFFFFFFF:
                    self.compress_size = counts[idx]
                    idx += 1

                if self.header_offset == 0xffffffff:
                    old = self.header_offset
                    self.header_offset = counts[idx]
                    idx+=1

            extra = extra[ln+4:]


class _ZipDecrypter:
    """Class to handle decryption of files stored within a ZIP archive.

    ZIP supports a password-based form of encryption. Even though known
    plaintext attacks have been found against it, it is still useful
    to be able to get data out of such a file.

    Usage:
        zd = _ZipDecrypter(mypwd)
        plain_char = zd(cypher_char)
        plain_text = map(zd, cypher_text)
    """

    def _GenerateCRCTable():
        """Generate a CRC-32 table.

        ZIP encryption uses the CRC32 one-byte primitive for scrambling some
        internal keys. We noticed that a direct implementation is faster than
        relying on binascii.crc32().
        """
        poly = 0xedb88320
        table = [0] * 256
        for i in range(256):
            crc = i
            for j in range(8):
                if crc & 1:
                    crc = ((crc >> 1) & 0x7FFFFFFF) ^ poly
                else:
                    crc = ((crc >> 1) & 0x7FFFFFFF)
            table[i] = crc
        return table
    crctable = _GenerateCRCTable()

    def _crc32(self, ch, crc):
        """Compute the CRC32 primitive on one byte."""
        return ((crc >> 8) & 0xffffff) ^ self.crctable[(crc ^ ch) & 0xff]

    def __init__(self, pwd):
        self.key0 = 305419896
        self.key1 = 591751049
        self.key2 = 878082192
        for p in pwd:
            self._UpdateKeys(p)

    def _UpdateKeys(self, c):
        self.key0 = self._crc32(c, self.key0)
        self.key1 = (self.key1 + (self.key0 & 255)) & 4294967295
        self.key1 = (self.key1 * 134775813 + 1) & 4294967295
        self.key2 = self._crc32((self.key1 >> 24) & 255, self.key2)

    def __call__(self, c):
        """Decrypt a single character."""
        assert isinstance(c, int)
        k = self.key2 | 2
        c = c ^ (((k * (k^1)) >> 8) & 255)
        self._UpdateKeys(c)
        return c

class ZipExtFile(io.BufferedIOBase):
    """File-like object for reading an archive member.
       Is returned by ZipFile.open().
    """

    # Max size supported by decompressor.
    MAX_N = 1 << 31 - 1

    # Read from compressed files in 4k blocks.
    MIN_READ_SIZE = 4096

    # Search for universal newlines or line chunks.
    PATTERN = re.compile(br'^(?P<chunk>[^\r\n]+)|(?P<newline>\n|\r\n?)')

    def __init__(self, fileobj, mode, zipinfo, decrypter=None):
        self._fileobj = fileobj
        self._decrypter = decrypter

        self._compress_type = zipinfo.compress_type
        self._compress_size = zipinfo.compress_size
        self._compress_left = zipinfo.compress_size

        if self._compress_type == ZIP_DEFLATED:
            self._decompressor = zlib.decompressobj(-15)
        self._unconsumed = b''

        self._readbuffer = b''
        self._offset = 0

        self._universal = 'U' in mode
        self.newlines = None

        # Adjust read size for encrypted files since the first 12 bytes
        # are for the encryption/password information.
        if self._decrypter is not None:
            self._compress_left -= 12

        self.mode = mode
        self.name = zipinfo.filename

        if hasattr(zipinfo, 'CRC'):
            self._expected_crc = zipinfo.CRC
            self._running_crc = crc32(b'') & 0xffffffff
        else:
            self._expected_crc = None

    def readline(self, limit=-1):
        """Read and return a line from the stream.

        If limit is specified, at most limit bytes will be read.
        """

        if not self._universal and limit < 0:
            # Shortcut common case - newline found in buffer.
            i = self._readbuffer.find(b'\n', self._offset) + 1
            if i > 0:
                line = self._readbuffer[self._offset: i]
                self._offset = i
                return line

        if not self._universal:
            return io.BufferedIOBase.readline(self, limit)

        line = b''
        while limit < 0 or len(line) < limit:
            readahead = self.peek(2)
            if readahead == b'':
                return line

            #
            # Search for universal newlines or line chunks.
            #
            # The pattern returns either a line chunk or a newline, but not
            # both. Combined with peek(2), we are assured that the sequence
            # '\r\n' is always retrieved completely and never split into
            # separate newlines - '\r', '\n' due to coincidental readaheads.
            #
            match = self.PATTERN.search(readahead)
            newline = match.group('newline')
            if newline is not None:
                if self.newlines is None:
                    self.newlines = []
                if newline not in self.newlines:
                    self.newlines.append(newline)
                self._offset += len(newline)
                return line + b'\n'

            chunk = match.group('chunk')
            if limit >= 0:
                chunk = chunk[: limit - len(line)]

            self._offset += len(chunk)
            line += chunk

        return line

    def peek(self, n=1):
        """Returns buffered bytes without advancing the position."""
        if n > len(self._readbuffer) - self._offset:
            chunk = self.read(n)
            self._offset -= len(chunk)

        # Return up to 512 bytes to reduce allocation overhead for tight loops.
        return self._readbuffer[self._offset: self._offset + 512]

    def readable(self):
        return True

    def read(self, n=-1):
        """Read and return up to n bytes.
        If the argument is omitted, None, or negative, data is read and returned until EOF is reached..
        """

        buf = b''
        while n < 0 or n is None or n > len(buf):
            data = self.read1(n)
            if len(data) == 0:
                return buf

            buf += data

        return buf

    def _update_crc(self, newdata, eof):
        # Update the CRC using the given data.
        if self._expected_crc is None:
            # No need to compute the CRC if we don't have a reference value
            return
        self._running_crc = crc32(newdata, self._running_crc) & 0xffffffff
        # Check the CRC if we're at the end of the file
        if eof and self._running_crc != self._expected_crc:
            raise BadZipfile("Bad CRC-32 for file %r" % self.name)

    def read1(self, n):
        """Read up to n bytes with at most one read() system call."""

        # Simplify algorithm (branching) by transforming negative n to large n.
        if n < 0 or n is None:
            n = self.MAX_N

        # Bytes available in read buffer.
        len_readbuffer = len(self._readbuffer) - self._offset

        # Read from file.
        if self._compress_left > 0 and n > len_readbuffer + len(self._unconsumed):
            nbytes = n - len_readbuffer - len(self._unconsumed)
            nbytes = max(nbytes, self.MIN_READ_SIZE)
            nbytes = min(nbytes, self._compress_left)

            data = self._fileobj.read(nbytes)
            self._compress_left -= len(data)

            if data and self._decrypter is not None:
                data = bytes(map(self._decrypter, data))

            if self._compress_type == ZIP_STORED:
                self._update_crc(data, eof=(self._compress_left==0))
                self._readbuffer = self._readbuffer[self._offset:] + data
                self._offset = 0
            else:
                # Prepare deflated bytes for decompression.
                self._unconsumed += data

        # Handle unconsumed data.
        if (len(self._unconsumed) > 0 and n > len_readbuffer and
            self._compress_type == ZIP_DEFLATED):
            data = self._decompressor.decompress(
                self._unconsumed,
                max(n - len_readbuffer, self.MIN_READ_SIZE)
            )

            self._unconsumed = self._decompressor.unconsumed_tail
            eof = len(self._unconsumed) == 0 and self._compress_left == 0
            if eof:
                data += self._decompressor.flush()

            self._update_crc(data, eof=eof)
            self._readbuffer = self._readbuffer[self._offset:] + data
            self._offset = 0

        # Read from buffer.
        data = self._readbuffer[self._offset: self._offset + n]
        self._offset += len(data)
        return data



class ZipFile:
    """ Class with methods to open, read, write, close, list zip files.

    z = ZipFile(file, mode="r", compression=ZIP_STORED, allowZip64=False)

    file: Either the path to the file, or a file-like object.
          If it is a path, the file will be opened and closed by ZipFile.
    mode: The mode can be either read "r", write "w" or append "a".
    compression: ZIP_STORED (no compression) or ZIP_DEFLATED (requires zlib).
    allowZip64: if True ZipFile will create files with ZIP64 extensions when
                needed, otherwise it will raise an exception when this would
                be necessary.

    """

    fp = None                   # Set here since __del__ checks it

    def __init__(self, file, mode="r", compression=ZIP_STORED, allowZip64=False):
        """Open the ZIP file with mode read "r", write "w" or append "a"."""
        if mode not in ("r", "w", "a"):
            raise RuntimeError('ZipFile() requires mode "r", "w", or "a"')

        if compression == ZIP_STORED:
            pass
        elif compression == ZIP_DEFLATED:
            if not zlib:
                raise RuntimeError(
                      "Compression requires the (missing) zlib module")
        else:
            raise RuntimeError("That compression method is not supported")

        self._allowZip64 = allowZip64
        self._didModify = False
        self.debug = 0  # Level of printing: 0 through 3
        self.NameToInfo = {}    # Find file info given name
        self.filelist = []      # List of ZipInfo instances for archive
        self.compression = compression  # Method of compression
        self.mode = key = mode.replace('b', '')[0]
        self.pwd = None
        self.comment = b''

        # Check if we were passed a file-like object
        if isinstance(file, str):
            # No, it's a filename
            self._filePassed = 0
            self.filename = file
            modeDict = {'r' : 'rb', 'w': 'wb', 'a' : 'r+b'}
            try:
                self.fp = io.open(file, modeDict[mode])
            except IOError:
                if mode == 'a':
                    mode = key = 'w'
                    self.fp = io.open(file, modeDict[mode])
                else:
                    raise
        else:
            self._filePassed = 1
            self.fp = file
            self.filename = getattr(file, 'name', None)

        if key == 'r':
            self._GetContents()
        elif key == 'w':
            pass
        elif key == 'a':
            try:                        # See if file is a zip file
                self._RealGetContents()
                # seek to start of directory and overwrite
                self.fp.seek(self.start_dir, 0)
            except BadZipfile:          # file is not a zip file, just append
                self.fp.seek(0, 2)
        else:
            if not self._filePassed:
                self.fp.close()
                self.fp = None
            raise RuntimeError('Mode must be "r", "w" or "a"')

    def __enter__(self):
        return self

    def __exit__(self, type, value, traceback):
        self.close()

    def _GetContents(self):
        """Read the directory, making sure we close the file if the format
        is bad."""
        try:
            self._RealGetContents()
        except BadZipfile:
            if not self._filePassed:
                self.fp.close()
                self.fp = None
            raise

    def _RealGetContents(self):
        """Read in the table of contents for the ZIP file."""
        fp = self.fp
        endrec = _EndRecData(fp)
        if not endrec:
            raise BadZipfile("File is not a zip file")
        if self.debug > 1:
            print(endrec)
        size_cd = endrec[_ECD_SIZE]             # bytes in central directory
        offset_cd = endrec[_ECD_OFFSET]         # offset of central directory
        self.comment = endrec[_ECD_COMMENT]     # archive comment

        # "concat" is zero, unless zip was concatenated to another file
        concat = endrec[_ECD_LOCATION] - size_cd - offset_cd
        if endrec[_ECD_SIGNATURE] == stringEndArchive64:
            # If Zip64 extension structures are present, account for them
            concat -= (sizeEndCentDir64 + sizeEndCentDir64Locator)

        if self.debug > 2:
            inferred = concat + offset_cd
            print("given, inferred, offset", offset_cd, inferred, concat)
        # self.start_dir:  Position of start of central directory
        self.start_dir = offset_cd + concat
        fp.seek(self.start_dir, 0)
        data = fp.read(size_cd)
        fp = io.BytesIO(data)
        total = 0
        while total < size_cd:
            centdir = fp.read(sizeCentralDir)
            if centdir[0:4] != stringCentralDir:
                raise BadZipfile("Bad magic number for central directory")
            centdir = struct.unpack(structCentralDir, centdir)
            if self.debug > 2:
                print(centdir)
            filename = fp.read(centdir[_CD_FILENAME_LENGTH])
            flags = centdir[5]
            if flags & 0x800:
                # UTF-8 file names extension
                filename = filename.decode('utf-8')
            else:
                # Historical ZIP filename encoding
                filename = filename.decode('cp437')
            # Create ZipInfo instance to store file information
            x = ZipInfo(filename)
            x.extra = fp.read(centdir[_CD_EXTRA_FIELD_LENGTH])
            x.comment = fp.read(centdir[_CD_COMMENT_LENGTH])
            x.header_offset = centdir[_CD_LOCAL_HEADER_OFFSET]
            (x.create_version, x.create_system, x.extract_version, x.reserved,
                x.flag_bits, x.compress_type, t, d,
                x.CRC, x.compress_size, x.file_size) = centdir[1:12]
            x.volume, x.internal_attr, x.external_attr = centdir[15:18]
            # Convert date/time code to (year, month, day, hour, min, sec)
            x._raw_time = t
            x.date_time = ( (d>>9)+1980, (d>>5)&0xF, d&0x1F,
                                     t>>11, (t>>5)&0x3F, (t&0x1F) * 2 )

            x._decodeExtra()
            x.header_offset = x.header_offset + concat
            self.filelist.append(x)
            self.NameToInfo[x.filename] = x

            # update total bytes read from central directory
            total = (total + sizeCentralDir + centdir[_CD_FILENAME_LENGTH]
                     + centdir[_CD_EXTRA_FIELD_LENGTH]
                     + centdir[_CD_COMMENT_LENGTH])

            if self.debug > 2:
                print("total", total)


    def namelist(self):
        """Return a list of file names in the archive."""
        l = []
        for data in self.filelist:
            l.append(data.filename)
        return l

    def infolist(self):
        """Return a list of class ZipInfo instances for files in the
        archive."""
        return self.filelist

    def printdir(self, file=None):
        """Print a table of contents for the zip file."""
        print("%-46s %19s %12s" % ("File Name", "Modified    ", "Size"),
              file=file)
        for zinfo in self.filelist:
            date = "%d-%02d-%02d %02d:%02d:%02d" % zinfo.date_time[:6]
            print("%-46s %s %12d" % (zinfo.filename, date, zinfo.file_size),
                  file=file)

    def testzip(self):
        """Read all the files and check the CRC."""
        chunk_size = 2 ** 20
        for zinfo in self.filelist:
            try:
                # Read by chunks, to avoid an OverflowError or a
                # MemoryError with very large embedded files.
                f = self.open(zinfo.filename, "r")
                while f.read(chunk_size):     # Check CRC-32
                    pass
            except BadZipfile:
                return zinfo.filename

    def getinfo(self, name):
        """Return the instance of ZipInfo given 'name'."""
        info = self.NameToInfo.get(name)
        if info is None:
            raise KeyError(
                'There is no item named %r in the archive' % name)

        return info

    def setpassword(self, pwd):
        """Set default password for encrypted files."""
        assert isinstance(pwd, bytes)
        self.pwd = pwd

    def read(self, name, pwd=None):
        """Return file bytes (as a string) for name."""
        return self.open(name, "r", pwd).read()

    def open(self, name, mode="r", pwd=None):
        """Return file-like object for 'name'."""
        if mode not in ("r", "U", "rU"):
            raise RuntimeError('open() requires mode "r", "U", or "rU"')
        if not self.fp:
            raise RuntimeError(
                  "Attempt to read ZIP archive that was already closed")

        # Only open a new file for instances where we were not
        # given a file object in the constructor
        if self._filePassed:
            zef_file = self.fp
        else:
            zef_file = io.open(self.filename, 'rb')

        # Make sure we have an info object
        if isinstance(name, ZipInfo):
            # 'name' is already an info object
            zinfo = name
        else:
            # Get info object for name
            zinfo = self.getinfo(name)

        zef_file.seek(zinfo.header_offset, 0)

        # Skip the file header:
        fheader = zef_file.read(sizeFileHeader)
        if fheader[0:4] != stringFileHeader:
            raise BadZipfile("Bad magic number for file header")

        fheader = struct.unpack(structFileHeader, fheader)
        fname = zef_file.read(fheader[_FH_FILENAME_LENGTH])
        if fheader[_FH_EXTRA_FIELD_LENGTH]:
            zef_file.read(fheader[_FH_EXTRA_FIELD_LENGTH])

        if fname != zinfo.orig_filename.encode("utf-8"):
            raise BadZipfile(
                  'File name in directory %r and header %r differ.'
                  % (zinfo.orig_filename, fname))

        # check for encrypted flag & handle password
        is_encrypted = zinfo.flag_bits & 0x1
        zd = None
        if is_encrypted:
            if not pwd:
                pwd = self.pwd
            if not pwd:
                raise RuntimeError("File %s is encrypted, "
                                   "password required for extraction" % name)

            zd = _ZipDecrypter(pwd)
            # The first 12 bytes in the cypher stream is an encryption header
            #  used to strengthen the algorithm. The first 11 bytes are
            #  completely random, while the 12th contains the MSB of the CRC,
            #  or the MSB of the file time depending on the header type
            #  and is used to check the correctness of the password.
            bytes = zef_file.read(12)
            h = list(map(zd, bytes[0:12]))
            if zinfo.flag_bits & 0x8:
                # compare against the file type from extended local headers
                check_byte = (zinfo._raw_time >> 8) & 0xff
            else:
                # compare against the CRC otherwise
                check_byte = (zinfo.CRC >> 24) & 0xff
            if h[11] != check_byte:
                raise RuntimeError("Bad password for file", name)

        return  ZipExtFile(zef_file, mode, zinfo, zd)

    def extract(self, member, path=None, pwd=None):
        """Extract a member from the archive to the current working directory,
           using its full name. Its file information is extracted as accurately
           as possible. `member' may be a filename or a ZipInfo object. You can
           specify a different directory using `path'.
        """
        if not isinstance(member, ZipInfo):
            member = self.getinfo(member)

        if path is None:
            path = os.getcwd()

        return self._extract_member(member, path, pwd)

    def extractall(self, path=None, members=None, pwd=None):
        """Extract all members from the archive to the current working
           directory. `path' specifies a different directory to extract to.
           `members' is optional and must be a subset of the list returned
           by namelist().
        """
        if members is None:
            members = self.namelist()

        for zipinfo in members:
            self.extract(zipinfo, path, pwd)

    def _extract_member(self, member, targetpath, pwd):
        """Extract the ZipInfo object 'member' to a physical
           file on the path targetpath.
        """
        # build the destination pathname, replacing
        # forward slashes to platform specific separators.
        # Strip trailing path separator, unless it represents the root.
        if (targetpath[-1:] in (os.path.sep, os.path.altsep)
            and len(os.path.splitdrive(targetpath)[1]) > 1):
            targetpath = targetpath[:-1]

        # don't include leading "/" from file name if present
        if member.filename[0] == '/':
            targetpath = os.path.join(targetpath, member.filename[1:])
        else:
            targetpath = os.path.join(targetpath, member.filename)

        targetpath = os.path.normpath(targetpath)

        # Create all upper directories if necessary.
        upperdirs = os.path.dirname(targetpath)
        if upperdirs and not os.path.exists(upperdirs):
            os.makedirs(upperdirs)

        if member.filename[-1] == '/':
            if not os.path.isdir(targetpath):
                os.mkdir(targetpath)
            return targetpath

        source = self.open(member, pwd=pwd)
        target = open(targetpath, "wb")
        shutil.copyfileobj(source, target)
        source.close()
        target.close()

        return targetpath

    def _writecheck(self, zinfo):
        """Check for errors before writing a file to the archive."""
        if zinfo.filename in self.NameToInfo:
            if self.debug:      # Warning for duplicate names
                print("Duplicate name:", zinfo.filename)
        if self.mode not in ("w", "a"):
            raise RuntimeError('write() requires mode "w" or "a"')
        if not self.fp:
            raise RuntimeError(
                  "Attempt to write ZIP archive that was already closed")
        if zinfo.compress_type == ZIP_DEFLATED and not zlib:
            raise RuntimeError(
                  "Compression requires the (missing) zlib module")
        if zinfo.compress_type not in (ZIP_STORED, ZIP_DEFLATED):
            raise RuntimeError("That compression method is not supported")
        if zinfo.file_size > ZIP64_LIMIT:
            if not self._allowZip64:
                raise LargeZipFile("Filesize would require ZIP64 extensions")
        if zinfo.header_offset > ZIP64_LIMIT:
            if not self._allowZip64:
                raise LargeZipFile(
                      "Zipfile size would require ZIP64 extensions")

    def write(self, filename, arcname=None, compress_type=None):
        """Put the bytes from filename into the archive under the name
        arcname."""
        if not self.fp:
            raise RuntimeError(
                  "Attempt to write to ZIP archive that was already closed")

        st = os.stat(filename)
        isdir = stat.S_ISDIR(st.st_mode)
        mtime = time.localtime(st.st_mtime)
        date_time = mtime[0:6]
        # Create ZipInfo instance to store file information
        if arcname is None:
            arcname = filename
        arcname = os.path.normpath(os.path.splitdrive(arcname)[1])
        while arcname[0] in (os.sep, os.altsep):
            arcname = arcname[1:]
        if isdir:
            arcname += '/'
        zinfo = ZipInfo(arcname, date_time)
        zinfo.external_attr = (st[0] & 0xFFFF) << 16      # Unix attributes
        if compress_type is None:
            zinfo.compress_type = self.compression
        else:
            zinfo.compress_type = compress_type

        zinfo.file_size = st.st_size
        zinfo.flag_bits = 0x00
        zinfo.header_offset = self.fp.tell()    # Start of header bytes

        self._writecheck(zinfo)
        self._didModify = True

        if isdir:
            zinfo.file_size = 0
            zinfo.compress_size = 0
            zinfo.CRC = 0
            self.filelist.append(zinfo)
            self.NameToInfo[zinfo.filename] = zinfo
            self.fp.write(zinfo.FileHeader())
            return

        with open(filename, "rb") as fp:
            # Must overwrite CRC and sizes with correct data later
            zinfo.CRC = CRC = 0
            zinfo.compress_size = compress_size = 0
            zinfo.file_size = file_size = 0
            self.fp.write(zinfo.FileHeader())
            if zinfo.compress_type == ZIP_DEFLATED:
                cmpr = zlib.compressobj(zlib.Z_DEFAULT_COMPRESSION,
                     zlib.DEFLATED, -15)
            else:
                cmpr = None
            while 1:
                buf = fp.read(1024 * 8)
                if not buf:
                    break
                file_size = file_size + len(buf)
                CRC = crc32(buf, CRC) & 0xffffffff
                if cmpr:
                    buf = cmpr.compress(buf)
                    compress_size = compress_size + len(buf)
                self.fp.write(buf)
        if cmpr:
            buf = cmpr.flush()
            compress_size = compress_size + len(buf)
            self.fp.write(buf)
            zinfo.compress_size = compress_size
        else:
            zinfo.compress_size = file_size
        zinfo.CRC = CRC
        zinfo.file_size = file_size
        # Seek backwards and write CRC and file sizes
        position = self.fp.tell()       # Preserve current position in file
        self.fp.seek(zinfo.header_offset + 14, 0)
        self.fp.write(struct.pack("<LLL", zinfo.CRC, zinfo.compress_size,
              zinfo.file_size))
        self.fp.seek(position, 0)
        self.filelist.append(zinfo)
        self.NameToInfo[zinfo.filename] = zinfo

    def writestr(self, zinfo_or_arcname, data, compress_type=None):
        """Write a file into the archive.  The contents is 'data', which
        may be either a 'str' or a 'bytes' instance; if it is a 'str',
        it is encoded as UTF-8 first.
        'zinfo_or_arcname' is either a ZipInfo instance or
        the name of the file in the archive."""
        if isinstance(data, str):
            data = data.encode("utf-8")
        if not isinstance(zinfo_or_arcname, ZipInfo):
            zinfo = ZipInfo(filename=zinfo_or_arcname,
                            date_time=time.localtime(time.time())[:6])
            zinfo.compress_type = self.compression
            zinfo.external_attr = 0o600 << 16
        else:
            zinfo = zinfo_or_arcname

        if not self.fp:
            raise RuntimeError(
                  "Attempt to write to ZIP archive that was already closed")

        zinfo.file_size = len(data)            # Uncompressed size
        zinfo.header_offset = self.fp.tell()    # Start of header data
        if compress_type is not None:
            zinfo.compress_type = compress_type

        self._writecheck(zinfo)
        self._didModify = True
        zinfo.CRC = crc32(data) & 0xffffffff       # CRC-32 checksum
        if zinfo.compress_type == ZIP_DEFLATED:
            co = zlib.compressobj(zlib.Z_DEFAULT_COMPRESSION,
                 zlib.DEFLATED, -15)
            data = co.compress(data) + co.flush()
            zinfo.compress_size = len(data)    # Compressed size
        else:
            zinfo.compress_size = zinfo.file_size
        zinfo.header_offset = self.fp.tell()    # Start of header data
        self.fp.write(zinfo.FileHeader())
        self.fp.write(data)
        self.fp.flush()
        if zinfo.flag_bits & 0x08:
            # Write CRC and file sizes after the file data
            self.fp.write(struct.pack("<LLL", zinfo.CRC, zinfo.compress_size,
                  zinfo.file_size))
        self.filelist.append(zinfo)
        self.NameToInfo[zinfo.filename] = zinfo

    def __del__(self):
        """Call the "close()" method in case the user forgot."""
        self.close()

    def close(self):
        """Close the file, and for mode "w" and "a" write the ending
        records."""
        if self.fp is None:
            return

        if self.mode in ("w", "a") and self._didModify: # write ending records
            count = 0
            pos1 = self.fp.tell()
            for zinfo in self.filelist:         # write central directory
                count = count + 1
                dt = zinfo.date_time
                dosdate = (dt[0] - 1980) << 9 | dt[1] << 5 | dt[2]
                dostime = dt[3] << 11 | dt[4] << 5 | (dt[5] // 2)
                extra = []
                if zinfo.file_size > ZIP64_LIMIT \
                        or zinfo.compress_size > ZIP64_LIMIT:
                    extra.append(zinfo.file_size)
                    extra.append(zinfo.compress_size)
                    file_size = 0xffffffff
                    compress_size = 0xffffffff
                else:
                    file_size = zinfo.file_size
                    compress_size = zinfo.compress_size

                if zinfo.header_offset > ZIP64_LIMIT:
                    extra.append(zinfo.header_offset)
                    header_offset = 0xffffffff
                else:
                    header_offset = zinfo.header_offset

                extra_data = zinfo.extra
                if extra:
                    # Append a ZIP64 field to the extra's
                    extra_data = struct.pack(
                            '<HH' + 'Q'*len(extra),
                            1, 8*len(extra), *extra) + extra_data

                    extract_version = max(45, zinfo.extract_version)
                    create_version = max(45, zinfo.create_version)
                else:
                    extract_version = zinfo.extract_version
                    create_version = zinfo.create_version

                try:
                    filename, flag_bits = zinfo._encodeFilenameFlags()
                    centdir = struct.pack(structCentralDir,
                        stringCentralDir, create_version,
                        zinfo.create_system, extract_version, zinfo.reserved,
                        flag_bits, zinfo.compress_type, dostime, dosdate,
                        zinfo.CRC, compress_size, file_size,
                        len(filename), len(extra_data), len(zinfo.comment),
                        0, zinfo.internal_attr, zinfo.external_attr,
                        header_offset)
                except DeprecationWarning:
                    print((structCentralDir, stringCentralDir, create_version,
                        zinfo.create_system, extract_version, zinfo.reserved,
                        zinfo.flag_bits, zinfo.compress_type, dostime, dosdate,
                        zinfo.CRC, compress_size, file_size,
                        len(zinfo.filename), len(extra_data), len(zinfo.comment),
                        0, zinfo.internal_attr, zinfo.external_attr,
                        header_offset), file=sys.stderr)
                    raise
                self.fp.write(centdir)
                self.fp.write(filename)
                self.fp.write(extra_data)
                self.fp.write(zinfo.comment)

            pos2 = self.fp.tell()
            # Write end-of-zip-archive record
            centDirCount = count
            centDirSize = pos2 - pos1
            centDirOffset = pos1
            if (centDirCount >= ZIP_FILECOUNT_LIMIT or
                centDirOffset > ZIP64_LIMIT or
                centDirSize > ZIP64_LIMIT):
                # Need to write the ZIP64 end-of-archive records
                zip64endrec = struct.pack(
                        structEndArchive64, stringEndArchive64,
                        44, 45, 45, 0, 0, centDirCount, centDirCount,
                        centDirSize, centDirOffset)
                self.fp.write(zip64endrec)

                zip64locrec = struct.pack(
                        structEndArchive64Locator,
                        stringEndArchive64Locator, 0, pos2, 1)
                self.fp.write(zip64locrec)
                centDirCount = min(centDirCount, 0xFFFF)
                centDirSize = min(centDirSize, 0xFFFFFFFF)
                centDirOffset = min(centDirOffset, 0xFFFFFFFF)

            # check for valid comment length
            if len(self.comment) >= ZIP_MAX_COMMENT:
                if self.debug > 0:
                    msg = 'Archive comment is too long; truncating to %d bytes' \
                          % ZIP_MAX_COMMENT
                self.comment = self.comment[:ZIP_MAX_COMMENT]

            endrec = struct.pack(structEndArchive, stringEndArchive,
                                 0, 0, centDirCount, centDirCount,
                                 centDirSize, centDirOffset, len(self.comment))
            self.fp.write(endrec)
            self.fp.write(self.comment)
            self.fp.flush()

        if not self._filePassed:
            self.fp.close()
        self.fp = None


class PyZipFile(ZipFile):
    """Class to create ZIP archives with Python library files and packages."""

    def writepy(self, pathname, basename=""):
        """Add all files from "pathname" to the ZIP archive.

        If pathname is a package directory, search the directory and
        all package subdirectories recursively for all *.py and enter
        the modules into the archive.  If pathname is a plain
        directory, listdir *.py and enter all modules.  Else, pathname
        must be a Python *.py file and the module will be put into the
        archive.  Added modules are always module.pyo or module.pyc.
        This method will compile the module.py into module.pyc if
        necessary.
        """
        dir, name = os.path.split(pathname)
        if os.path.isdir(pathname):
            initname = os.path.join(pathname, "__init__.py")
            if os.path.isfile(initname):
                # This is a package directory, add it
                if basename:
                    basename = "%s/%s" % (basename, name)
                else:
                    basename = name
                if self.debug:
                    print("Adding package in", pathname, "as", basename)
                fname, arcname = self._get_codename(initname[0:-3], basename)
                if self.debug:
                    print("Adding", arcname)
                self.write(fname, arcname)
                dirlist = os.listdir(pathname)
                dirlist.remove("__init__.py")
                # Add all *.py files and package subdirectories
                for filename in dirlist:
                    path = os.path.join(pathname, filename)
                    root, ext = os.path.splitext(filename)
                    if os.path.isdir(path):
                        if os.path.isfile(os.path.join(path, "__init__.py")):
                            # This is a package directory, add it
                            self.writepy(path, basename)  # Recursive call
                    elif ext == ".py":
                        fname, arcname = self._get_codename(path[0:-3],
                                         basename)
                        if self.debug:
                            print("Adding", arcname)
                        self.write(fname, arcname)
            else:
                # This is NOT a package directory, add its files at top level
                if self.debug:
                    print("Adding files from directory", pathname)
                for filename in os.listdir(pathname):
                    path = os.path.join(pathname, filename)
                    root, ext = os.path.splitext(filename)
                    if ext == ".py":
                        fname, arcname = self._get_codename(path[0:-3],
                                         basename)
                        if self.debug:
                            print("Adding", arcname)
                        self.write(fname, arcname)
        else:
            if pathname[-3:] != ".py":
                raise RuntimeError(
                      'Files added with writepy() must end with ".py"')
            fname, arcname = self._get_codename(pathname[0:-3], basename)
            if self.debug:
                print("Adding file", arcname)
            self.write(fname, arcname)

    def _get_codename(self, pathname, basename):
        """Return (filename, archivename) for the path.

        Given a module name path, return the correct file path and
        archive name, compiling if necessary.  For example, given
        /python/lib/string, return (/python/lib/string.pyc, string).
        """
        file_py  = pathname + ".py"
        file_pyc = pathname + ".pyc"
        file_pyo = pathname + ".pyo"
        pycache_pyc = imp.cache_from_source(file_py, True)
        pycache_pyo = imp.cache_from_source(file_py, False)
        if (os.path.isfile(file_pyo) and
            os.stat(file_pyo).st_mtime >= os.stat(file_py).st_mtime):
            # Use .pyo file.
            arcname = fname = file_pyo
        elif (os.path.isfile(file_pyc) and
              os.stat(file_pyc).st_mtime >= os.stat(file_py).st_mtime):
            # Use .pyc file.
            arcname = fname = file_pyc
        elif (os.path.isfile(pycache_pyc) and
              os.stat(pycache_pyc).st_mtime >= os.stat(file_py).st_mtime):
            # Use the __pycache__/*.pyc file, but write it to the legacy pyc
            # file name in the archive.
            fname = pycache_pyc
            arcname = file_pyc
        elif (os.path.isfile(pycache_pyo) and
              os.stat(pycache_pyo).st_mtime >= os.stat(file_py).st_mtime):
            # Use the __pycache__/*.pyo file, but write it to the legacy pyo
            # file name in the archive.
            fname = pycache_pyo
            arcname = file_pyo
        else:
            # Compile py into PEP 3147 pyc file.
            import py_compile
            if self.debug:
                print("Compiling", file_py)
            try:
                py_compile.compile(file_py, doraise=True)
            except py_compile.PyCompileError as error:
                print(err.msg)
                fname = file_py
            else:
                fname = (pycache_pyc if __debug__ else pycache_pyo)
                arcname = (file_pyc if __debug__ else file_pyo)
        archivename = os.path.split(arcname)[1]
        if basename:
            archivename = "%s/%s" % (basename, archivename)
        return (fname, archivename)


def main(args = None):
    import textwrap
    USAGE=textwrap.dedent("""\
        Usage:
            zipfile.py -l zipfile.zip        # Show listing of a zipfile
            zipfile.py -t zipfile.zip        # Test if a zipfile is valid
            zipfile.py -e zipfile.zip target # Extract zipfile into target dir
            zipfile.py -c zipfile.zip src ... # Create zipfile from sources
        """)
    if args is None:
        args = sys.argv[1:]

    if not args or args[0] not in ('-l', '-c', '-e', '-t'):
        print(USAGE)
        sys.exit(1)

    if args[0] == '-l':
        if len(args) != 2:
            print(USAGE)
            sys.exit(1)
        zf = ZipFile(args[1], 'r')
        zf.printdir()
        zf.close()

    elif args[0] == '-t':
        if len(args) != 2:
            print(USAGE)
            sys.exit(1)
        zf = ZipFile(args[1], 'r')
        badfile = zf.testzip()
        if badfile:
            print("The following enclosed file is corrupted: {!r}".format(badfile))
        print("Done testing")

    elif args[0] == '-e':
        if len(args) != 3:
            print(USAGE)
            sys.exit(1)

        zf = ZipFile(args[1], 'r')
        out = args[2]
        for path in zf.namelist():
            if path.startswith('./'):
                tgt = os.path.join(out, path[2:])
            else:
                tgt = os.path.join(out, path)

            tgtdir = os.path.dirname(tgt)
            if not os.path.exists(tgtdir):
                os.makedirs(tgtdir)
            with open(tgt, 'wb') as fp:
                fp.write(zf.read(path))
        zf.close()

    elif args[0] == '-c':
        if len(args) < 3:
            print(USAGE)
            sys.exit(1)

        def addToZip(zf, path, zippath):
            if os.path.isfile(path):
                zf.write(path, zippath, ZIP_DEFLATED)
            elif os.path.isdir(path):
                for nm in os.listdir(path):
                    addToZip(zf,
                            os.path.join(path, nm), os.path.join(zippath, nm))
            # else: ignore

        zf = ZipFile(args[1], 'w', allowZip64=True)
        for src in args[2:]:
            addToZip(zf, src, os.path.basename(src))

        zf.close()

if __name__ == "__main__":
    main()