Source code for girder.utility.ziputil

"""
This module is essentially a subset of the python zipfile module that has been
modified to allow it to read arbitrary streams (using generators) as input,
instead of only accepting files. It also streams the output using generators.

Example of creating and consuming a streaming zip:

    zip = ziputil.ZipGenerator('TopLevelFolder')

    for data in zip.addFile(lambda: 'hello world', 'hello.txt'):
        yield data

    yield zip.footer()
"""

import binascii
import os
import struct
import sys
import time

try:
    import zlib
except ImportError:
    zlib = None

__all__ = ('STORE', 'DEFLATE', 'ZipGenerator')


Z64_LIMIT = (1 << 31) - 1
Z_FILECOUNT_LIMIT = 1 << 16
STORE = 0
DEFLATE = 8


class ZipInfo:

    __slots__ = (
        'filename',
        'timestamp',
        'compressType',
        'createSystem',
        'createVersion',
        'extractVersion',
        'externalAttr',
        'headerOffset',
        'crc',
        'compressSize',
        'fileSize'
    )

    def __init__(self, filename, timestamp):
        # Terminate the file name at the first null byte.  Null bytes in file
        # names are used as tricks by viruses in archives.
        if os.sep != '/' and os.sep in filename:
            filename = filename.replace(os.sep, '/')
        if isinstance(filename, str):
            filename = filename.encode('utf8')
        # Escaping or locale conversion should go here
        nullByte = filename.find(b'\x00')
        if nullByte >= 0:
            filename = filename[0:nullByte]
        self.filename = filename
        self.timestamp = timestamp
        self.compressType = STORE
        if sys.platform == 'win32':
            self.createSystem = 0
        else:
            self.createSystem = 3
        self.createVersion = 20
        self.extractVersion = 20
        self.externalAttr = 0

    def dataDescriptor(self):
        if self.compressSize > Z64_LIMIT or self.fileSize > Z64_LIMIT:
            fmt = b'<4sLQQ'
        else:
            fmt = b'<4sLLL'
        return struct.pack(
            fmt, b'PK\x07\x08', self.crc, self.compressSize, self.fileSize)

    def fileHeader(self):
        """
        Return the per-file header as a string.
        """
        dt = self.timestamp
        dosdate = (dt[0] - 1980) << 9 | dt[1] << 5 | dt[2]
        dostime = dt[3] << 11 | dt[4] << 5 | (dt[5] // 2)

        header = struct.pack(
            b'<4s2B4HLLL2H', b'PK\003\004', self.extractVersion, 0, 0x8,
            self.compressType, dostime, dosdate, 0, 0, 0, len(self.filename), 0)
        return header + self.filename


[docs]class ZipGenerator: """ This class can be used to create a streaming zip file that consumes from one generator and writes to another. """ def __init__(self, rootPath='', compression=STORE): """ :param rootPath: The root path for all files within this archive. :type rootPath: str :param compression: Whether files in this archive should be compressed. :type """ if compression == DEFLATE and not zlib: raise RuntimeError('Missing zlib module') self.files = [] self.compression = compression self.useCRC = True self.rootPath = rootPath self.offset = 0 def _advanceOffset(self, data): """ Call this whenever data is added to the archive to keep track of the offset of the data. """ self.offset += len(data) return data
[docs] def addFile(self, generator, path): """ Generates data to add a file at the given path in the archive. :param generator: Generator function that will yield the file contents. :type generator: function :param path: The path within the archive for this entry. :type path: str """ fullpath = os.path.join(self.rootPath, path) header = ZipInfo(fullpath, time.localtime()[0:6]) header.externalAttr = (0o100644 & 0xFFFF) << 16 header.compressType = self.compression header.headerOffset = self.offset header.crc = crc = 0 header.compressSize = compressSize = 0 header.fileSize = fileSize = 0 yield self._advanceOffset(header.fileHeader()) if header.compressType == DEFLATE: compressor = zlib.compressobj(zlib.Z_DEFAULT_COMPRESSION, zlib.DEFLATED, -15) else: compressor = None for buf in generator(): if not buf: break if isinstance(buf, str): buf = buf.encode('utf8') fileSize += len(buf) if self.useCRC: crc = binascii.crc32(buf, crc) & 0xFFFFFFFF if compressor: buf = compressor.compress(buf) compressSize += len(buf) yield self._advanceOffset(buf) if compressor: buf = compressor.flush() compressSize += len(buf) yield self._advanceOffset(buf) header.compressSize = compressSize else: header.compressSize = fileSize header.crc = crc header.fileSize = fileSize yield self._advanceOffset(header.dataDescriptor()) self.files.append(header)
[docs] def footer(self): """ Once all zip files have been added with addFile, you must call this to get the footer of the archive. """ data = [] count = 0 pos1 = self.offset for header in self.files: count += 1 dt = header.timestamp dosdate = (dt[0] - 1980) << 9 | dt[1] << 5 | dt[2] dostime = dt[3] << 11 | dt[4] << 5 | (dt[5] // 2) extra = [] if header.fileSize > Z64_LIMIT or header.compressSize > Z64_LIMIT: extra.append(header.fileSize) extra.append(header.compressSize) fileSize = compressSize = 0xffffffff else: fileSize = header.fileSize compressSize = header.compressSize if header.headerOffset > Z64_LIMIT: extra.append(header.headerOffset) headerOffset = 0xffffffff else: headerOffset = header.headerOffset if extra: extraData = struct.pack( b'<hh' + b'q' * len(extra), 1, 8 * len(extra), *extra) extractVersion = max(45, header.extractVersion) createVersion = max(45, header.createVersion) else: extraData = b'' extractVersion = header.extractVersion createVersion = header.createVersion centdir = struct.pack( b'<4s4B4HLLL5HLL', b'PK\001\002', createVersion, header.createSystem, extractVersion, 0, 0x8, header.compressType, dostime, dosdate, header.crc, compressSize, fileSize, len(header.filename), len(extraData), 0, 0, 0, header.externalAttr, headerOffset) data.append(self._advanceOffset(centdir)) data.append(self._advanceOffset(header.filename)) data.append(self._advanceOffset(extraData)) pos2 = self.offset offsetVal = pos1 size = pos2 - pos1 if pos1 > Z64_LIMIT or size > Z64_LIMIT or count >= Z_FILECOUNT_LIMIT: zip64endrec = struct.pack( b'<4sqhhLLqqqq', b'PK\x06\x06', 44, 45, 45, 0, 0, count, count, size, pos1) data.append(self._advanceOffset(zip64endrec)) zip64locrec = struct.pack(b'<4sLqL', b'PK\x06\x07', 0, pos2, 1) data.append(self._advanceOffset(zip64locrec)) count = min(count, 0xFFFF) size = min(size, 0xFFFFFFFF) offsetVal = min(offsetVal, 0xFFFFFFFF) endrec = struct.pack(b'<4s4H2LH', b'PK\005\006', 0, 0, count, count, size, offsetVal, 0) data.append(self._advanceOffset(endrec)) return b''.join(data)