|
| 1 | +import io |
| 2 | +from pathlib import Path |
| 3 | + |
| 4 | +import lzfse |
| 5 | +from structlog import get_logger |
| 6 | + |
| 7 | +from unblob.file_utils import ( |
| 8 | + Endian, |
| 9 | + File, |
| 10 | + FileSystem, |
| 11 | + convert_int8, |
| 12 | + convert_int64, |
| 13 | +) |
| 14 | +from unblob.models import ( |
| 15 | + Extractor, |
| 16 | + ExtractResult, |
| 17 | + Handler, |
| 18 | + HandlerDoc, |
| 19 | + HandlerType, |
| 20 | + HexString, |
| 21 | + Reference, |
| 22 | + ValidChunk, |
| 23 | +) |
| 24 | + |
| 25 | +logger = get_logger() |
| 26 | + |
| 27 | +APPLE_ARCHIVE_C_DEFINITIONS = r""" |
| 28 | + typedef struct field_header { |
| 29 | + char tag[4]; |
| 30 | + uint8_t length; |
| 31 | + } field_header_t; |
| 32 | +
|
| 33 | + typedef struct data_field { |
| 34 | + char tag[4]; |
| 35 | + uint64_t size; |
| 36 | + } data_field_t; |
| 37 | +""" |
| 38 | + |
| 39 | + |
| 40 | +def _field_patp( |
| 41 | + file: File, _fs: FileSystem, current_path: str | None |
| 42 | +) -> tuple[str | None, bool]: |
| 43 | + # PATP: Path Property (1-byte length + string) |
| 44 | + len_bytes = file.read(1) |
| 45 | + if not len_bytes: |
| 46 | + return current_path, False |
| 47 | + length = convert_int8(len_bytes, Endian.LITTLE) |
| 48 | + return file.read(length).decode("utf-8", errors="ignore"), True |
| 49 | + |
| 50 | + |
| 51 | +def _field_data( |
| 52 | + file: File, fs: FileSystem, current_path: str | None |
| 53 | +) -> tuple[str | None, bool]: |
| 54 | + # DATA: Data Property (8-byte size + LZFSE/Raw blob) |
| 55 | + size_bytes = file.read(8) |
| 56 | + if not size_bytes: |
| 57 | + return current_path, False |
| 58 | + blob_size = convert_int64(size_bytes, Endian.LITTLE) |
| 59 | + compressed_data = file.read(blob_size) |
| 60 | + if current_path: |
| 61 | + try: |
| 62 | + fs.write_bytes(Path(current_path), lzfse.decompress(compressed_data)) |
| 63 | + except Exception: |
| 64 | + fs.write_bytes(Path(current_path), compressed_data) |
| 65 | + return current_path, True |
| 66 | + |
| 67 | + |
| 68 | +def _field_lnkp( |
| 69 | + file: File, _fs: FileSystem, current_path: str | None |
| 70 | +) -> tuple[str | None, bool]: |
| 71 | + # LNKP: Symbolic Link Property (1-byte length + string) |
| 72 | + len_bytes = file.read(1) |
| 73 | + if not len_bytes: |
| 74 | + return current_path, True |
| 75 | + length = convert_int8(len_bytes, Endian.LITTLE) |
| 76 | + target = file.read(length).decode("utf-8", errors="ignore") |
| 77 | + if current_path: |
| 78 | + logger.debug("atlas symlink found", source=current_path, target=target) |
| 79 | + return current_path, True |
| 80 | + |
| 81 | + |
| 82 | +def _field_xata( |
| 83 | + file: File, _fs: FileSystem, current_path: str | None |
| 84 | +) -> tuple[str | None, bool]: |
| 85 | + # XATA: Extended Attributes (skip or parse CRC) |
| 86 | + len_bytes = file.read(1) |
| 87 | + if not len_bytes: |
| 88 | + return current_path, True |
| 89 | + length = convert_int8(len_bytes, Endian.LITTLE) |
| 90 | + current_pos = file.tell() |
| 91 | + file.seek(0, io.SEEK_END) |
| 92 | + file_size = file.tell() |
| 93 | + file.seek(current_pos) |
| 94 | + skip_bytes = length + 4 |
| 95 | + if current_pos + skip_bytes > file_size: |
| 96 | + logger.warning("Invalid XATA field length, stopping parse") |
| 97 | + return current_path, False |
| 98 | + file.seek(skip_bytes, io.SEEK_CUR) |
| 99 | + return current_path, True |
| 100 | + |
| 101 | + |
| 102 | +def _field_typ1( |
| 103 | + file: File, _fs: FileSystem, current_path: str | None |
| 104 | +) -> tuple[str | None, bool]: |
| 105 | + # TYP1: Entry Type (1 byte) |
| 106 | + file.seek(1, io.SEEK_CUR) |
| 107 | + return current_path, True |
| 108 | + |
| 109 | + |
| 110 | +_FIELD_HANDLERS = { |
| 111 | + "PATP": _field_patp, |
| 112 | + "DATA": _field_data, |
| 113 | + "LNKP": _field_lnkp, |
| 114 | + "XATA": _field_xata, |
| 115 | + "TYP1": _field_typ1, |
| 116 | +} |
| 117 | + |
| 118 | + |
| 119 | +class AppleArchiveExtractor(Extractor): |
| 120 | + def extract(self, inpath: Path, outdir: Path) -> ExtractResult: |
| 121 | + fs = FileSystem(outdir) |
| 122 | + |
| 123 | + with File.from_path(inpath) as file: |
| 124 | + magic = file.read(4) |
| 125 | + if magic != b"AA01": |
| 126 | + return ExtractResult(reports=[]) |
| 127 | + |
| 128 | + current_path: str | None = None |
| 129 | + |
| 130 | + while True: |
| 131 | + field_tag = file.read(4) |
| 132 | + if len(field_tag) < 4: |
| 133 | + break |
| 134 | + tag = field_tag.decode("ascii", errors="ignore") |
| 135 | + handler = _FIELD_HANDLERS.get(tag) |
| 136 | + if handler is None: |
| 137 | + continue |
| 138 | + current_path, ok = handler(file, fs, current_path) |
| 139 | + if not ok: |
| 140 | + break |
| 141 | + |
| 142 | + return ExtractResult(reports=fs.problems) |
| 143 | + |
| 144 | + |
| 145 | +class AppleArchiveHandler(Handler): |
| 146 | + NAME = "apple_archive" |
| 147 | + PATTERNS = [HexString("41 41 30 31")] # "AA01" |
| 148 | + EXTRACTOR = AppleArchiveExtractor() |
| 149 | + |
| 150 | + DOC = HandlerDoc( |
| 151 | + name="Apple Archive", |
| 152 | + description="Apple Archive is Apple's proprietary archive format introduced with macOS Big Sur, used for distributing macOS software updates and installers. Files begin with the AA01 magic and contain field-tagged entries encoding paths, LZFSE-compressed data blobs, symbolic links, and extended attributes.", |
| 153 | + handler_type=HandlerType.ARCHIVE, |
| 154 | + vendor="Apple", |
| 155 | + references=[ |
| 156 | + Reference( |
| 157 | + title="Apple Archive - Apple Developer Documentation", |
| 158 | + url="https://developer.apple.com/documentation/applearchive", |
| 159 | + ), |
| 160 | + ], |
| 161 | + limitations=[ |
| 162 | + "Only PATP/DATA/LNKP/XATA/TYP1 field tags are handled; other tags are silently skipped", |
| 163 | + "Symlink targets are logged but not created in the output directory", |
| 164 | + ], |
| 165 | + ) |
| 166 | + |
| 167 | + def calculate_chunk(self, file: File, start_offset: int) -> ValidChunk | None: |
| 168 | + file.seek(0, io.SEEK_END) |
| 169 | + end_offset = file.tell() |
| 170 | + return ValidChunk(start_offset=start_offset, end_offset=end_offset) |
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