SickGear/lib/hachoir/parser/archive/sevenzip.py

"""
7zip file parser

Informations:
- File 7zformat.txt of 7-zip SDK:
  http://www.7-zip.org/sdk.html

Author: Olivier SCHWAB
Creation date: 6 december 2006

Updated by: Robert Xiao
Date: February 26 2011
"""

from hachoir.parser import Parser
from hachoir.field import (Field, FieldSet, ParserError, CString,
                               Enum, Bit, Bits, UInt8, UInt32, UInt64,
                               Bytes, RawBytes, TimestampWin64)
from hachoir.stream import StringInputStream
from hachoir.core.endian import LITTLE_ENDIAN
from hachoir.core.text_handler import textHandler, hexadecimal
from hachoir.core.tools import alignValue, humanFilesize, makePrintable
from hachoir.parser.common.msdos import MSDOSFileAttr32

try:
    from pylzma import decompress as lzmadecompress
    has_lzma = True
except ImportError:
    has_lzma = False


class SZUInt64(Field):
    """
    Variable length UInt64, where the first byte gives both the number of bytes
    needed and the upper byte value.
    """

    def __init__(self, parent, name, max_size=None, description=None):
        Field.__init__(self, parent, name, size=8, description=description)
        value = 0
        addr = self.absolute_address
        mask = 0x80
        firstByte = parent.stream.readBits(addr, 8, LITTLE_ENDIAN)
        for i in range(8):
            addr += 8
            if not (firstByte & mask):
                value += ((firstByte & (mask - 1)) << (8 * i))
                break
            value |= (parent.stream.readBits(
                addr, 8, LITTLE_ENDIAN) << (8 * i))
            mask >>= 1
            self._size += 8
        self.createValue = lambda: value


kEnd = 0x00
kHeader = 0x01
kArchiveProperties = 0x02
kAdditionalStreamsInfo = 0x03
kMainStreamsInfo = 0x04
kFilesInfo = 0x05
kPackInfo = 0x06
kUnPackInfo = 0x07
kSubStreamsInfo = 0x08
kSize = 0x09
kCRC = 0x0A
kFolder = 0x0B
kCodersUnPackSize = 0x0C
kNumUnPackStream = 0x0D
kEmptyStream = 0x0E
kEmptyFile = 0x0F
kAnti = 0x10
kName = 0x11
kCreationTime = 0x12
kLastAccessTime = 0x13
kLastWriteTime = 0x14
kWinAttributes = 0x15
kComment = 0x16
kEncodedHeader = 0x17
kStartPos = 0x18
kDummy = 0x19

PROP_IDS = {
    kEnd: 'kEnd',
    kHeader: 'kHeader',
    kArchiveProperties: 'kArchiveProperties',
    kAdditionalStreamsInfo: 'kAdditionalStreamsInfo',
    kMainStreamsInfo: 'kMainStreamsInfo',
    kFilesInfo: 'kFilesInfo',
    kPackInfo: 'kPackInfo',
    kUnPackInfo: 'kUnPackInfo',
    kSubStreamsInfo: 'kSubStreamsInfo',
    kSize: 'kSize',
    kCRC: 'kCRC',
    kFolder: 'kFolder',
    kCodersUnPackSize: 'kCodersUnPackSize',
    kNumUnPackStream: 'kNumUnPackStream',
    kEmptyStream: 'kEmptyStream',
    kEmptyFile: 'kEmptyFile',
    kAnti: 'kAnti',
    kName: 'kName',
    kCreationTime: 'kCreationTime',
    kLastAccessTime: 'kLastAccessTime',
    kLastWriteTime: 'kLastWriteTime',
    kWinAttributes: 'kWinAttributes',
    kComment: 'kComment',
    kEncodedHeader: 'kEncodedHeader',
    kStartPos: 'kStartPos',
    kDummy: 'kDummy',
}

PROP_DESC = {
    kEnd: 'End-of-header marker',

    kHeader: 'Archive header',

    kArchiveProperties: 'Archive properties',

    kAdditionalStreamsInfo: 'AdditionalStreamsInfo',
    kMainStreamsInfo: 'MainStreamsInfo',
    kFilesInfo: 'FilesInfo',

    kPackInfo: 'PackInfo',
    kUnPackInfo: 'UnPackInfo',
    kSubStreamsInfo: 'SubStreamsInfo',

    kSize: 'Size',
    kCRC: 'CRC',

    kFolder: 'Folder',

    kCodersUnPackSize: 'CodersUnPackSize',
    kNumUnPackStream: 'NumUnPackStream',

    kEmptyStream: 'EmptyStream',
    kEmptyFile: 'EmptyFile',
    kAnti: 'Anti',

    kName: 'Name',
    kCreationTime: 'CreationTime',
    kLastAccessTime: 'LastAccessTime',
    kLastWriteTime: 'LastWriteTime',
    kWinAttributes: 'WinAttributes',
    kComment: 'Comment',

    kEncodedHeader: 'Encoded archive header',

    kStartPos: 'Unknown',
    kDummy: 'Dummy entry',
}


def ReadNextByte(self):
    return self.stream.readBits(self.absolute_address + self.current_size, 8, self.endian)


def PropID(self, name):
    return Enum(UInt8(self, name), PROP_IDS)


class SevenZipBitVector(FieldSet):

    def __init__(self, parent, name, num, has_all_byte=False, **args):
        FieldSet.__init__(self, parent, name, **args)
        self.has_all_byte = has_all_byte
        self.num = num

    def createFields(self):
        if self.has_all_byte:
            yield Enum(UInt8(self, "all_defined"), {0: 'False', 1: 'True'})
            if self['all_defined'].value:
                return
        nbytes = alignValue(self.num, 8) // 8
        ctr = 0
        for i in range(nbytes):
            for j in reversed(range(8)):
                yield Bit(self, "bit[%d]" % (ctr + j))
            ctr += 8

    def isAllDefined(self):
        return self.has_all_byte and self['all_defined'].value

    def isDefined(self, index):
        if self.isAllDefined():
            return True
        return self['bit[%d]' % index].value

    def createValue(self):
        if self.isAllDefined():
            return list(range(self.num))
        return [i for i in range(self.num) if self['bit[%d]' % i].value]

    def createDisplay(self):
        if self.isAllDefined():
            return 'all'
        return ','.join(str(i) for i in self.value)


class ArchiveProperty(FieldSet):

    def createFields(self):
        yield PropID(self, "id")
        size = SZUInt64(self, "size")
        yield size
        if size.value:
            yield RawBytes(self, "data", size.value)

    def createDescription(self):
        return self['id'].display


class ArchiveProperties(FieldSet):

    def createFields(self):
        yield PropID(self, "id")
        while not self.eof:
            uid = ReadNextByte(self)
            if uid == kEnd:
                yield PropID(self, "end_marker")
                break
            yield ArchiveProperty(self, "prop[]")


class Digests(FieldSet):

    def __init__(self, parent, name, num_digests, digest_desc=None, desc=None):
        FieldSet.__init__(self, parent, name, desc)
        self.num_digests = num_digests
        if digest_desc is None:
            self.digest_desc = ['stream %d' % i for i in range(num_digests)]
        else:
            self.digest_desc = digest_desc

    def createFields(self):
        yield PropID(self, "id")
        definearr = SevenZipBitVector(
            self, "defined", self.num_digests, has_all_byte=True)
        yield definearr
        for index in definearr.value:
            yield textHandler(UInt32(self, "digest[]",
                                     "Digest for %s" % self.digest_desc[index]), hexadecimal)


class PackInfo(FieldSet):

    def createFields(self):
        yield PropID(self, "id")

        yield SZUInt64(self, "pack_pos", "File offset to the packed data")
        num = SZUInt64(self, "num_pack_streams", "Number of packed streams")
        yield num

        while not self.eof:
            uid = ReadNextByte(self)
            if uid == kEnd:
                yield PropID(self, "end_marker")
                break
            elif uid == kSize:
                yield PropID(self, "size_marker")
                for index in range(num.value):
                    yield SZUInt64(self, "pack_size[]")
            elif uid == kCRC:
                yield Digests(self, "digests", num.value)
            else:
                raise ParserError("Unexpected ID (%i)" % uid)


METHODS = {
    b"\0": "Copy",
    b"\3": "Delta",
    b"\4": "x86_BCJ",
    b"\5": "PowerPC",
    b"\6": "IA64",
    b"\7": "ARM_LE",
    b"\x08": "ARMT_LE",  # thumb
    b"\x09": "SPARC",
    b"\x21": "LZMA2",
    b"\2\3\2": "Common-Swap-2",
    b"\2\3\4": "Common-Swap-4",
    b"\3\1\1": "7z-LZMA",
    b"\3\3\1\3": "7z-Branch-x86-BCJ",
    b"\3\3\1\x1b": "7z-Branch-x86-BCJ2",
    b"\3\3\2\5": "7z-Branch-PowerPC-BE",
    b"\3\3\3\1": "7z-Branch-Alpha-LE",
    b"\3\3\4\1": "7z-Branch-IA64-LE",
    b"\3\3\5\1": "7z-Branch-ARM-LE",
    b"\3\3\6\5": "7z-Branch-M68-BE",
    b"\3\3\7\1": "7z-Branch-ARMT-LE",
    b"\3\3\x08\5": "7z-Branch-SPARC-BE",
    b"\3\4\1": "7z-PPMD",
    b"\3\x7f\1": "7z-Experimental",
    b"\4\0": "Reserved",
    b"\4\1\0": "Zip-Copy",
    b"\4\1\1": "Zip-Shrink",
    b"\4\1\6": "Zip-Implode",
    b"\4\1\x08": "Zip-Deflate",
    b"\4\1\x09": "Zip-Deflate64",
    b"\4\1\x10": "Zip-BZip2",
    b"\4\1\x14": "Zip-LZMA",
    b"\4\1\x60": "Zip-JPEG",
    b"\4\1\x61": "Zip-WavPack",
    b"\4\1\x62": "Zip-PPMD",
    b"\4\1\x63": "Zip-wzAES",
    b"\4\2\2": "BZip2",
    b"\4\3\1": "RAR-15",
    b"\4\3\2": "RAR-20",
    b"\4\3\3": "RAR-29",
    b"\4\4\1": "Arj3",
    b"\4\4\2": "Arj4",
    b"\4\5": "Z",
    b"\4\6": "LZH",
    b"\4\7": "7z-Reserved",
    b"\4\x08": "CAB",
    b"\4\x09\1": "NSIS-Deflate",
    b"\4\x09\2": "NSIS-BZip2",
    b"\6\0": "Crypto-Reserved",
    b"\6\1\x00": "Crypto-AES128-ECB",
    b"\6\1\x01": "Crypto-AES128-CBC",
    b"\6\1\x02": "Crypto-AES128-CFB",
    b"\6\1\x03": "Crypto-AES128-OFB",
    b"\6\1\x04": "Crypto-AES128-CTR",
    b"\6\1\x40": "Crypto-AES192-ECB",
    b"\6\1\x41": "Crypto-AES192-CBC",
    b"\6\1\x42": "Crypto-AES192-CFB",
    b"\6\1\x43": "Crypto-AES192-OFB",
    b"\6\1\x44": "Crypto-AES192-CTR",
    b"\6\1\x80": "Crypto-AES256-ECB",
    b"\6\1\x81": "Crypto-AES256-CBC",
    b"\6\1\x82": "Crypto-AES256-CFB",
    b"\6\1\x83": "Crypto-AES256-OFB",
    b"\6\1\x84": "Crypto-AES256-CTR",
    b"\6\1\xc0": "Crypto-AES-ECB",
    b"\6\1\xc1": "Crypto-AES-CBC",
    b"\6\1\xc2": "Crypto-AES-CFB",
    b"\6\1\xc3": "Crypto-AES-OFB",
    b"\6\1\xc4": "Crypto-AES-CTR",
    b"\6\7": "Crypto-Reserved",
    b"\6\x0f": "Crypto-Reserved",
    b"\6\xf0": "Crypto-Misc",
    b"\6\xf1\1\1": "Crypto-Zip",
    b"\6\xf1\3\2": "Crypto-RAR-Unknown",
    b"\6\xf1\3\3": "Crypto-RAR-29",  # AES128
    b"\6\xf1\7\1": "Crypto-7z",  # AES256
    b"\7\0": "Hash-None",
    b"\7\1": "Hash-CRC",
    b"\7\2": "Hash-SHA1",
    b"\7\3": "Hash-SHA256",
    b"\7\4": "Hash-SHA384",
    b"\7\5": "Hash-SHA512",
    b"\7\xf0": "Hash-Misc",
    b"\7\xf1\3\3": "Hash-RAR-29",  # modified SHA1
    b"\7\xf1\7\1": "Hash-7z",  # SHA256
}


class Coder(FieldSet):

    def createFields(self):
        yield Bits(self, "id_size", 4)
        yield Bit(self, "is_not_simple", "If unset, stream setup is simple")
        yield Bit(self, "has_attribs", "Are there compression properties attached?")
        yield Bit(self, "unused[]")
        yield Bit(self, "is_not_last_method", "Are there more methods after this one in the alternative method list?")
        size = self['id_size'].value
        if size > 0:
            yield Enum(RawBytes(self, "id", size), METHODS)
        if self['is_not_simple'].value:
            yield SZUInt64(self, "num_stream_in")
            yield SZUInt64(self, "num_stream_out")
            self.info("Streams: IN=%u    OUT=%u" %
                      (self["num_stream_in"].value, self["num_stream_out"].value))
        if self['has_attribs'].value:
            size = SZUInt64(self, "properties_size")
            yield size
            yield RawBytes(self, "properties", size.value)

    def _get_num_streams(self, direction):
        if self['is_not_simple'].value:
            return self['num_stream_%s' % direction].value
        return 1
    in_streams = property(lambda self: self._get_num_streams('in'))
    out_streams = property(lambda self: self._get_num_streams('out'))


class CoderList(FieldSet):

    def createFields(self):
        while not self.eof:
            field = Coder(self, "coder[]")
            yield field
            if not field['is_not_last_method'].value:
                break


class BindPairInfo(FieldSet):

    def createFields(self):
        # 64 bits values then cast to 32 in fact
        yield SZUInt64(self, "in_index")
        yield SZUInt64(self, "out_index")
        self.info("Indexes: IN=%u   OUT=%u" %
                  (self["in_index"].value, self["out_index"].value))


class Folder(FieldSet):

    def createFields(self):
        yield SZUInt64(self, "num_coders")
        num = self["num_coders"].value
        self.info("Folder: %u codecs" % num)

        in_streams = out_streams = 0

        # Coder info
        for index in range(num):
            ci = CoderList(self, "coders[]")
            yield ci
            in_streams += ci['coder[0]'].in_streams
            out_streams += ci['coder[0]'].out_streams
        self._in_streams = in_streams
        self._out_streams = out_streams

        # Bind pairs
        self.info("out streams: %u" % out_streams)
        for index in range(out_streams - 1):
            yield BindPairInfo(self, "bind_pair[]")

        # Packed streams
        # @todo: Actually find mapping
        packed_streams = in_streams - out_streams + 1
        if packed_streams > 1:
            for index in range(packed_streams):
                yield SZUInt64(self, "pack_stream[]")

    def _get_num_streams(self, direction):
        list(self)
        return getattr(self, '_' + direction + '_streams')
    in_streams = property(lambda self: self._get_num_streams('in'))
    out_streams = property(lambda self: self._get_num_streams('out'))


class UnpackInfo(FieldSet):

    def createFields(self):
        yield PropID(self, "id")

        yield PropID(self, "folder_marker")
        assert self['folder_marker'].value == kFolder
        yield SZUInt64(self, "num_folders")

        # Get generic info
        num = self["num_folders"].value
        self.info("%u folders" % num)
        yield UInt8(self, "is_external")

        if self['is_external'].value:
            yield SZUInt64(self, "folder_data_offset", "Offset to folder data within data stream")
        else:
            # Read folder items
            for folder_index in range(num):
                yield Folder(self, "folder[]")

        yield PropID(self, "unpacksize_marker")
        assert self['unpacksize_marker'].value == kCodersUnPackSize
        for folder_index in range(num):
            folder = self["folder[%u]" % folder_index]
            for index in range(folder.out_streams):
                yield SZUInt64(self, "unpack_size[%d][%d]" % (folder_index, index))

        # Extract digests
        while not self.eof:
            uid = ReadNextByte(self)
            if uid == kEnd:
                yield PropID(self, "end_marker")
                break
            elif uid == kCRC:
                yield Digests(self, "digests", num)
            else:
                raise ParserError("Unexpected ID (%i)" % uid)


class SubStreamInfo(FieldSet):

    def createFields(self):
        yield PropID(self, "id")
        num_folders = self['../unpack_info/num_folders'].value
        num_unpackstreams = [1] * num_folders
        while not self.eof:
            uid = ReadNextByte(self)
            if uid == kEnd:
                yield PropID(self, "end_marker")
                break
            elif uid == kNumUnPackStream:
                yield PropID(self, "num_unpackstream_marker")
                for i in range(num_folders):
                    field = SZUInt64(self, "num_unpackstreams[]")
                    yield field
                    num_unpackstreams[i] = field.value
            elif uid == kSize:
                yield PropID(self, "size_marker")
                for i in range(num_folders):
                    # The last substream's size is the stream size minus the
                    # other substreams.
                    for j in range(num_unpackstreams[i] - 1):
                        yield SZUInt64(self, "unpack_size[%d][%d]" % (i, j))
            elif uid == kCRC:
                digests = []
                for i in range(num_folders):
                    if num_unpackstreams[i] == 1 and 'digests' in self['../unpack_info']:
                        continue
                    for j in range(num_unpackstreams[i]):
                        digests.append('folder %i, stream %i' % (i, j))
                yield Digests(self, "digests", len(digests), digests)
            else:
                raise ParserError("Unexpected ID (%i)" % uid)


class StreamsInfo(FieldSet):

    def createFields(self):
        yield PropID(self, "id")
        while not self.eof:
            uid = ReadNextByte(self)
            if uid == kEnd:
                yield PropID(self, "end")
                break
            elif uid == kPackInfo:
                yield PackInfo(self, "pack_info", PROP_DESC[uid])
            elif uid == kUnPackInfo:
                yield UnpackInfo(self, "unpack_info", PROP_DESC[uid])
            elif uid == kSubStreamsInfo:
                yield SubStreamInfo(self, "substreams_info", PROP_DESC[uid])
            else:
                raise ParserError("Unexpected ID (%i)" % uid)


class EncodedHeader(StreamsInfo):
    pass


class EmptyStreamProperty(FieldSet):

    def createFields(self):
        yield PropID(self, "id")
        yield SZUInt64(self, "size")
        yield SevenZipBitVector(self, "vec", self['../num_files'].value)

    def createValue(self):
        return self['vec'].value

    def createDisplay(self):
        return self['vec'].display


class EmptyFileProperty(FieldSet):

    def createFields(self):
        yield PropID(self, "id")
        yield SZUInt64(self, "size")
        empty_streams = self['../empty_streams/vec'].value
        yield SevenZipBitVector(self, "vec", len(empty_streams))

    def createValue(self):
        empty_streams = self['../empty_streams/vec'].value
        return [empty_streams[i] for i in self['vec'].value]

    def createDisplay(self):
        return ','.join(str(i) for i in self.value)


class FileTimeProperty(FieldSet):

    def createFields(self):
        yield PropID(self, "id")
        yield SZUInt64(self, "size")
        definearr = SevenZipBitVector(
            self, "defined", self['../num_files'].value, has_all_byte=True)
        yield definearr
        yield UInt8(self, "is_external")
        if self['is_external'].value:
            yield SZUInt64(self, "folder_data_offset", "Offset to folder data within data stream")
        else:
            for index in definearr.value:
                yield TimestampWin64(self, "timestamp[%d]" % index)


class FileNames(FieldSet):

    def createFields(self):
        yield PropID(self, "id")
        yield SZUInt64(self, "size")
        yield UInt8(self, "is_external")
        if self['is_external'].value:
            yield SZUInt64(self, "folder_data_offset", "Offset to folder data within data stream")
        else:
            for index in range(self['../num_files'].value):
                yield CString(self, "name[%d]" % index, charset="UTF-16-LE")


class FileAttributes(FieldSet):

    def createFields(self):
        yield PropID(self, "id")
        yield SZUInt64(self, "size")
        definearr = SevenZipBitVector(
            self, "defined", self['../num_files'].value, has_all_byte=True)
        yield definearr
        yield UInt8(self, "is_external")
        if self['is_external'].value:
            yield SZUInt64(self, "folder_data_offset", "Offset to folder data within data stream")
        else:
            for index in definearr.value:
                yield MSDOSFileAttr32(self, "attributes[%d]" % index)


class FilesInfo(FieldSet):

    def createFields(self):
        yield PropID(self, "id")
        yield SZUInt64(self, "num_files")
        while not self.eof:
            uid = ReadNextByte(self)
            if uid == kEnd:
                yield PropID(self, "end_marker")
                break
            elif uid == kEmptyStream:
                yield EmptyStreamProperty(self, "empty_streams")
            elif uid == kEmptyFile:
                yield EmptyFileProperty(self, "empty_files")
            elif uid == kAnti:
                yield EmptyFileProperty(self, "anti_files")
            elif uid == kCreationTime:
                yield FileTimeProperty(self, "creation_time")
            elif uid == kLastAccessTime:
                yield FileTimeProperty(self, "access_time")
            elif uid == kLastWriteTime:
                yield FileTimeProperty(self, "modified_time")
            elif uid == kName:
                yield FileNames(self, "filenames")
            elif uid == kWinAttributes:
                yield FileAttributes(self, "attributes")
            elif uid == kDummy:
                yield ArchiveProperty(self, "dummy[]")
            else:
                yield ArchiveProperty(self, "prop[]")


class Header(FieldSet):

    def createFields(self):
        yield PropID(self, "id")
        while not self.eof:
            uid = ReadNextByte(self)
            if uid == kEnd:
                yield PropID(self, "end")
                break
            elif uid == kArchiveProperties:
                yield ArchiveProperties(self, "props", PROP_DESC[uid])
            elif uid == kAdditionalStreamsInfo:
                yield StreamsInfo(self, "additional_streams", PROP_DESC[uid])
            elif uid == kMainStreamsInfo:
                yield StreamsInfo(self, "main_streams", PROP_DESC[uid])
            elif uid == kFilesInfo:
                yield FilesInfo(self, "files_info", PROP_DESC[uid])
            else:
                raise ParserError("Unexpected ID %u" % uid)


class NextHeader(FieldSet):

    def __init__(self, parent, name, desc="Next header"):
        FieldSet.__init__(self, parent, name, desc)
        self._size = 8 * self["/signature/start_hdr/next_hdr_size"].value

    def createFields(self):
        uid = ReadNextByte(self)
        if uid == kHeader:
            yield Header(self, "header", PROP_DESC[uid])
        elif uid == kEncodedHeader:
            yield EncodedHeader(self, "encoded_hdr", PROP_DESC[uid])
        else:
            raise ParserError("Unexpected ID %u" % uid)


class NextHeaderParser(Parser):
    PARSER_TAGS = {
    }
    endian = LITTLE_ENDIAN

    def createFields(self):
        uid = ReadNextByte(self)
        if uid == kHeader:
            yield Header(self, "header", PROP_DESC[uid])
        elif uid == kEncodedHeader:
            yield EncodedHeader(self, "encoded_hdr", PROP_DESC[uid])
        else:
            raise ParserError("Unexpected ID %u" % uid)

    def validate(self):
        return True


class CompressedData(Bytes):

    def __init__(self, parent, name, length, decompressor, description=None,
                 parser=None, filename=None, mime_type=None, parser_class=None):
        if filename:
            if not isinstance(filename, str):
                filename = makePrintable(filename, "ISO-8859-1")
            if not description:
                description = 'File "%s" (%s)' % (
                    filename, humanFilesize(length))
        Bytes.__init__(self, parent, name, length, description)
        self.setupInputStream(decompressor, parser,
                              filename, mime_type, parser_class)

    def setupInputStream(self, decompressor, parser, filename, mime_type, parser_class):
        def createInputStream(cis, **args):
            tags = args.setdefault("tags", [])
            if parser_class:
                tags.append(("class", parser_class))
            if parser is not None:
                tags.append(("id", parser.PARSER_TAGS["id"]))
            if mime_type:
                tags.append(("mime", mime_type))
            if filename:
                tags.append(("filename", filename))
            return StringInputStream(decompressor(self.value), **args)
        self.setSubIStream(createInputStream)


def get_header_decompressor(self):
    unpack_info = self['/next_hdr/encoded_hdr/unpack_info']
    assert unpack_info['num_folders'].value == 1
    coder = unpack_info['folder[0]/coders[0]/coder[0]']
    method = METHODS[coder['id'].value]
    if method == 'Copy':
        return lambda data: data
    elif method == '7z-LZMA' and has_lzma:
        props = coder['properties'].value
        length = unpack_info['unpack_size[0][0]'].value
        return lambda data: lzmadecompress(props + data, maxlength=length)


def get_header_field(self, name, size, description=None):
    decompressor = get_header_decompressor(self)
    if decompressor is None:
        return RawBytes(self, name, size, description=description)
    return CompressedData(self, name, size, decompressor, description=description, parser_class=NextHeaderParser)


class Body(FieldSet):

    def __init__(self, parent, name, desc="Body data"):
        FieldSet.__init__(self, parent, name, desc)
        self._size = 8 * self["/signature/start_hdr/next_hdr_offset"].value

    def createFields(self):
        if "encoded_hdr" in self["/next_hdr"]:
            pack_size = sum([s.value for s in self.array(
                "/next_hdr/encoded_hdr/pack_info/pack_size")])
            body_size = self["/next_hdr/encoded_hdr/pack_info/pack_pos"].value
            if body_size:
                yield RawBytes(self, "compressed_data", body_size, "Compressed data")
            # Here we could check if copy method was used to "compress" it,
            # but this never happens, so just output "compressed file info"
            yield get_header_field(self, "compressed_file_info", pack_size,
                                   "Compressed file information")
            size = (self._size // 8) - pack_size - body_size
            if size > 0:
                yield RawBytes(self, "unknown_data", size)
        elif "header" in self["/next_hdr"]:
            yield RawBytes(self, "compressed_data", self._size // 8, "Compressed data")


class StartHeader(FieldSet):
    static_size = 160

    def createFields(self):
        yield textHandler(UInt64(self, "next_hdr_offset",
                                 "Next header offset"), hexadecimal)
        yield UInt64(self, "next_hdr_size", "Next header size")
        yield textHandler(UInt32(self, "next_hdr_crc",
                                 "Next header CRC"), hexadecimal)


class SignatureHeader(FieldSet):
    static_size = 96 + StartHeader.static_size

    def createFields(self):
        yield Bytes(self, "signature", 6, "Signature Header")
        yield UInt8(self, "major_ver", "Archive major version")
        yield UInt8(self, "minor_ver", "Archive minor version")
        yield textHandler(UInt32(self, "start_hdr_crc",
                                 "Start header CRC"), hexadecimal)
        yield StartHeader(self, "start_hdr", "Start header")


class SevenZipParser(Parser):
    MAGIC = b"7z\xbc\xaf\x27\x1c"
    PARSER_TAGS = {
        "id": "7zip",
        "category": "archive",
        "file_ext": ("7z",),
        "mime": ("application/x-7z-compressed",),
        "min_size": 32 * 8,
        "magic": ((MAGIC, 0),),
        "description": "Compressed archive in 7z format"
    }
    endian = LITTLE_ENDIAN

    def createFields(self):
        yield SignatureHeader(self, "signature", "Signature Header")
        yield Body(self, "body_data")
        yield NextHeader(self, "next_hdr")

    def validate(self):
        if self.stream.readBytes(0, len(self.MAGIC)) != self.MAGIC:
            return "Invalid signature"
        return True

    def createContentSize(self):
        size = self["/signature/start_hdr/next_hdr_offset"].value * 8
        size += self["/signature/start_hdr/next_hdr_size"].value * 8
        size += SignatureHeader.static_size
        return size