# pack.py -- For dealing with packed git objects. # Copyright (C) 2007 James Westby # Copyright (C) 2008-2013 Jelmer Vernooij # # SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later # Dulwich is dual-licensed under the Apache License, Version 2.0 and the GNU # General Public License as published by the Free Software Foundation; version 2.0 # or (at your option) any later version. You can redistribute it and/or # modify it under the terms of either of these two licenses. # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. # # You should have received a copy of the licenses; if not, see # for a copy of the GNU General Public License # and for a copy of the Apache # License, Version 2.0. # """Classes for dealing with packed git objects. A pack is a compact representation of a bunch of objects, stored using deltas where possible. They have two parts, the pack file, which stores the data, and an index that tells you where the data is. To find an object you look in all of the index files 'til you find a match for the object name. You then use the pointer got from this as a pointer in to the corresponding packfile. """ __all__ = [ "DEFAULT_PACK_DELTA_WINDOW_SIZE", "DEFAULT_PACK_INDEX_VERSION", "DELTA_TYPES", "OFS_DELTA", "PACK_SPOOL_FILE_MAX_SIZE", "REF_DELTA", "DeltaChainIterator", "FilePackIndex", "MemoryPackIndex", "ObjectContainer", "Pack", "PackChunkGenerator", "PackData", "PackFileDisappeared", "PackHint", "PackIndex", "PackIndex1", "PackIndex2", "PackIndex3", "PackIndexEntry", "PackIndexer", "PackInflater", "PackStreamCopier", "PackStreamReader", "PackedObjectContainer", "SHA1Reader", "SHA1Writer", "UnpackedObject", "UnpackedObjectIterator", "UnpackedObjectStream", "UnresolvedDeltas", "apply_delta", "bisect_find_sha", "chunks_length", "compute_buffer_sha", "compute_file_sha", "deltas_from_sorted_objects", "deltify_pack_objects", "extend_pack", "find_reusable_deltas", "full_unpacked_object", "generate_unpacked_objects", "iter_sha1", "load_pack_index", "load_pack_index_file", "obj_sha", "pack_header_chunks", "pack_object_chunks", "pack_object_header", "pack_objects_to_data", "read_pack_header", "read_pack_header_at", "read_zlib_chunks", "read_zlib_chunks_at", "sort_objects_for_delta", "take_msb_bytes", "take_msb_bytes_at", "unpack_object", "unpack_object_at", "verify_and_read", "write_pack", "write_pack_data", "write_pack_from_container", "write_pack_header", "write_pack_index", "write_pack_object", "write_pack_objects", ] import binascii from collections import defaultdict, deque from contextlib import suppress from io import BytesIO, UnsupportedOperation try: from cdifflib import CSequenceMatcher as SequenceMatcher except ModuleNotFoundError: from difflib import SequenceMatcher import logging import os import struct import sys import threading import warnings import zlib from collections.abc import Callable, Iterable, Iterator, Sequence, Set from hashlib import sha1, sha256 from itertools import chain from os import SEEK_END from struct import unpack_from from types import TracebackType from typing import ( IO, TYPE_CHECKING, Any, BinaryIO, Generic, Protocol, TypeVar, ) if sys.version_info >= (3, 11): from typing import Self else: from typing_extensions import Self import mmap from .errors import ApplyDeltaError, ChecksumMismatch from .file import GitFile, _GitFile from .lru_cache import LRUSizeCache from .object_format import OBJECT_FORMAT_TYPE_NUMS, SHA1, ObjectFormat from .objects import ( ObjectID, RawObjectID, ShaFile, hex_to_sha, object_header, sha_to_hex, ) if TYPE_CHECKING: from _hashlib import HASH as HashObject from .bitmap import PackBitmap from .commit_graph import CommitGraph from .object_store import BaseObjectStore from .refs import Ref logger = logging.getLogger(__name__) # Some platforms (e.g. plan9) don't support mmap properly has_mmap = sys.platform != "Plan9" OFS_DELTA = 6 REF_DELTA = 7 DELTA_TYPES = (OFS_DELTA, REF_DELTA) DEFAULT_PACK_DELTA_WINDOW_SIZE = 10 # Keep pack files under 16Mb in memory, otherwise write them out to disk PACK_SPOOL_FILE_MAX_SIZE = 16 * 1024 * 1024 # Default pack index version to use when none is specified DEFAULT_PACK_INDEX_VERSION = 2 OldUnpackedObject = tuple[bytes | int, list[bytes]] | list[bytes] | bytes ResolveExtRefFn = Callable[[RawObjectID | ObjectID], tuple[int, bytes | list[bytes]]] ProgressFn = Callable[[int, str], None] PackHint = tuple[int, bytes | None] def verify_and_read( read_func: Callable[[int], bytes], expected_hash: bytes, hash_algo: str, progress: Callable[[bytes], None] | None = None, ) -> Iterator[bytes]: """Read from stream, verify hash, then yield verified chunks. This function downloads data to a temporary file (in-memory for small files, on-disk for large ones) while computing its hash. Only after the hash is verified to match expected_hash will it yield any data. This prevents corrupted or malicious data from reaching the caller. Args: read_func: Function to read bytes (like file.read or HTTP response reader) expected_hash: Expected hash as hex string bytes (e.g., b'a3b2c1...') hash_algo: Hash algorithm name ('sha1' or 'sha256') progress: Optional progress callback Yields: Chunks of verified data (only after hash verification succeeds) Raises: ValueError: If hash doesn't match or algorithm unsupported """ from tempfile import SpooledTemporaryFile from .object_format import OBJECT_FORMATS # Get the hash function for this algorithm obj_format = OBJECT_FORMATS.get(hash_algo) if obj_format is None: raise ValueError(f"Unsupported hash algorithm: {hash_algo}") hasher = obj_format.new_hash() # Download to temporary file (memory or disk) while computing hash with SpooledTemporaryFile( max_size=PACK_SPOOL_FILE_MAX_SIZE, prefix="dulwich-verify-" ) as temp_file: # Read data, hash it, and write to temp file while True: chunk = read_func(65536) # Read in 64KB chunks if not chunk: break hasher.update(chunk) temp_file.write(chunk) # Verify hash BEFORE yielding any data computed_hash = hasher.hexdigest().encode("ascii") if computed_hash != expected_hash: raise ValueError( f"hash mismatch: expected {expected_hash.decode('ascii')}, " f"got {computed_hash.decode('ascii')}" ) # Hash verified! Now read from temp file and yield chunks if progress: progress(b"Hash verified, processing data\n") temp_file.seek(0) while True: chunk = temp_file.read(65536) if not chunk: break yield chunk class UnresolvedDeltas(Exception): """Delta objects could not be resolved.""" def __init__(self, shas: list[bytes]) -> None: """Initialize UnresolvedDeltas exception. Args: shas: List of SHA hashes for unresolved delta objects """ self.shas = shas class ObjectContainer(Protocol): """Protocol for objects that can contain git objects.""" def add_object(self, obj: ShaFile) -> None: """Add a single object to this object store.""" def add_objects( self, objects: Sequence[tuple[ShaFile, str | None]], progress: Callable[..., None] | None = None, ) -> "Pack | None": """Add a set of objects to this object store. Args: objects: Iterable over a list of (object, path) tuples progress: Progress callback for object insertion Returns: Optional Pack object of the objects written. """ def __contains__(self, sha1: "ObjectID") -> bool: """Check if a hex sha is present.""" ... def __getitem__(self, sha1: "ObjectID | RawObjectID") -> ShaFile: """Retrieve an object.""" ... def get_commit_graph(self) -> "CommitGraph | None": """Get the commit graph for this object store. Returns: CommitGraph object if available, None otherwise """ return None class PackedObjectContainer(ObjectContainer): """Container for objects packed in a pack file.""" def get_unpacked_object( self, sha1: "ObjectID | RawObjectID", *, include_comp: bool = False ) -> "UnpackedObject": """Get a raw unresolved object. Args: sha1: SHA-1 hash of the object include_comp: Whether to include compressed data Returns: UnpackedObject instance """ raise NotImplementedError(self.get_unpacked_object) def iterobjects_subset( self, shas: Iterable["ObjectID"], *, allow_missing: bool = False ) -> Iterator[ShaFile]: """Iterate over a subset of objects. Args: shas: Iterable of object SHAs to retrieve allow_missing: If True, skip missing objects Returns: Iterator of ShaFile objects """ raise NotImplementedError(self.iterobjects_subset) def iter_unpacked_subset( self, shas: Iterable["ObjectID | RawObjectID"], *, include_comp: bool = False, allow_missing: bool = False, convert_ofs_delta: bool = True, ) -> Iterator["UnpackedObject"]: """Iterate over unpacked objects from a subset of SHAs. Args: shas: Set of object SHAs to retrieve include_comp: Include compressed data if True allow_missing: If True, skip missing objects convert_ofs_delta: If True, convert offset deltas to ref deltas Returns: Iterator of UnpackedObject instances """ raise NotImplementedError(self.iter_unpacked_subset) class UnpackedObjectStream: """Abstract base class for a stream of unpacked objects.""" def __iter__(self) -> Iterator["UnpackedObject"]: """Iterate over unpacked objects.""" raise NotImplementedError(self.__iter__) def __len__(self) -> int: """Return the number of objects in the stream.""" raise NotImplementedError(self.__len__) def take_msb_bytes( read: Callable[[int], bytes], crc32: int | None = None ) -> tuple[list[int], int | None]: """Read bytes marked with most significant bit. Args: read: Read function crc32: Optional CRC32 checksum to update Returns: Tuple of (list of bytes read, updated CRC32 or None) """ ret: list[int] = [] while len(ret) == 0 or ret[-1] & 0x80: b = read(1) if crc32 is not None: crc32 = binascii.crc32(b, crc32) ret.append(ord(b[:1])) return ret, crc32 def take_msb_bytes_at( contents: "bytes | mmap.mmap", offset: int, crc32: int | None = None ) -> tuple[list[int], int, int | None]: """Read bytes marked with most significant bit from a buffer at an offset. Args: contents: Buffer to read from offset: Offset in contents to start reading at crc32: Optional CRC32 checksum to update Returns: Tuple of (list of bytes read, offset just past them, updated CRC32 or None) """ ret: list[int] = [] pos = offset while len(ret) == 0 or ret[-1] & 0x80: b = contents[pos : pos + 1] if not b: raise AssertionError(f"unexpected end of pack data at {pos}") pos += 1 if crc32 is not None: crc32 = binascii.crc32(b, crc32) ret.append(ord(b)) return ret, pos, crc32 class PackFileDisappeared(Exception): """Raised when a pack file unexpectedly disappears. This typically happens when a concurrent operation (e.g. ``git repack`` or ``git gc --auto``) removes a pack file between the moment dulwich snapshots the pack directory and the moment it actually opens the pack's ``.idx`` or ``.pack`` file. The ``obj`` attribute holds the :class:`Pack` (or :class:`FilePackIndex`) whose backing file vanished, so the caller can evict the stale object from its cache and rescan the pack directory. """ obj: "Pack | FilePackIndex" def __init__(self, obj: "Pack | FilePackIndex") -> None: """Initialize PackFileDisappeared exception. Args: obj: The pack or pack index that disappeared. """ self.obj = obj class UnpackedObject: """Class encapsulating an object unpacked from a pack file. These objects should only be created from within unpack_object. Most members start out as empty and are filled in at various points by read_zlib_chunks, unpack_object, DeltaChainIterator, etc. End users of this object should take care that the function they're getting this object from is guaranteed to set the members they need. """ __slots__ = [ "_sha", # Cached binary SHA. "comp_chunks", # Compressed object chunks. "crc32", # CRC32. "decomp_chunks", # Decompressed object chunks. "decomp_len", # Decompressed length of this object. "delta_base", # Delta base offset or SHA. "hash_func", # Hash function to use for computing object IDs. "obj_chunks", # Decompressed and delta-resolved chunks. "obj_type_num", # Type of this object. "offset", # Offset in its pack. "pack_type_num", # Type of this object in the pack (may be a delta). ] obj_type_num: int | None obj_chunks: list[bytes] | None delta_base: bytes | int | None decomp_chunks: list[bytes] comp_chunks: list[bytes] | None decomp_len: int | None crc32: int | None offset: int | None pack_type_num: int _sha: bytes | None hash_func: Callable[[], "HashObject"] # TODO(dborowitz): read_zlib_chunks and unpack_object could very well be # methods of this object. def __init__( self, pack_type_num: int, *, delta_base: bytes | int | None = None, decomp_len: int | None = None, crc32: int | None = None, sha: bytes | None = None, decomp_chunks: list[bytes] | None = None, offset: int | None = None, hash_func: Callable[[], "HashObject"] = sha1, ) -> None: """Initialize an UnpackedObject. Args: pack_type_num: Type number of this object in the pack delta_base: Delta base (offset or SHA) if this is a delta object decomp_len: Decompressed length of this object crc32: CRC32 checksum sha: SHA hash of the object decomp_chunks: Decompressed chunks offset: Offset in the pack file hash_func: Hash function to use (defaults to sha1) """ self.offset = offset self._sha = sha self.pack_type_num = pack_type_num self.delta_base = delta_base self.comp_chunks = None self.decomp_chunks: list[bytes] = decomp_chunks or [] if decomp_chunks is not None and decomp_len is None: self.decomp_len = sum(map(len, decomp_chunks)) else: self.decomp_len = decomp_len self.crc32 = crc32 self.hash_func = hash_func if pack_type_num in DELTA_TYPES: self.obj_type_num = None self.obj_chunks = None else: self.obj_type_num = pack_type_num self.obj_chunks = self.decomp_chunks self.delta_base = delta_base def sha(self) -> RawObjectID: """Return the binary SHA of this object.""" if self._sha is None: assert self.obj_type_num is not None and self.obj_chunks is not None self._sha = obj_sha(self.obj_type_num, self.obj_chunks, self.hash_func) return RawObjectID(self._sha) def sha_file(self) -> ShaFile: """Return a ShaFile from this object.""" assert self.obj_type_num is not None and self.obj_chunks is not None return ShaFile.from_raw_chunks(self.obj_type_num, self.obj_chunks) # Only provided for backwards compatibility with code that expects either # chunks or a delta tuple. def _obj(self) -> OldUnpackedObject: """Return the decompressed chunks, or (delta base, delta chunks).""" if self.pack_type_num in DELTA_TYPES: assert isinstance(self.delta_base, bytes | int) return (self.delta_base, self.decomp_chunks) else: return self.decomp_chunks def __eq__(self, other: object) -> bool: """Check equality with another UnpackedObject.""" if not isinstance(other, UnpackedObject): return False for slot in self.__slots__: if getattr(self, slot) != getattr(other, slot): return False return True def __ne__(self, other: object) -> bool: """Check inequality with another UnpackedObject.""" return not (self == other) def __repr__(self) -> str: """Return string representation of this UnpackedObject.""" data = [f"{s}={getattr(self, s)!r}" for s in self.__slots__] return "{}({})".format(self.__class__.__name__, ", ".join(data)) _ZLIB_BUFSIZE = 65536 # 64KB buffer for better I/O performance # Default maximum memory for caching delta base objects (matches Git's default # for core.deltaBaseCacheLimit). DEFAULT_DELTA_BASE_CACHE_LIMIT = 96 * 1024 * 1024 # 96 MiB def read_zlib_chunks( read_some: Callable[[int], bytes], unpacked: UnpackedObject, include_comp: bool = False, buffer_size: int = _ZLIB_BUFSIZE, ) -> bytes: """Read zlib data from a buffer. This function requires that the buffer have additional data following the compressed data, which is guaranteed to be the case for git pack files. Args: read_some: Read function that returns at least one byte, but may return less than the requested size. unpacked: An UnpackedObject to write result data to. If its crc32 attr is not None, the CRC32 of the compressed bytes will be computed using this starting CRC32. After this function, will have the following attrs set: * comp_chunks (if include_comp is True) * decomp_chunks * decomp_len * crc32 include_comp: If True, include compressed data in the result. buffer_size: Size of the read buffer. Returns: Leftover unused data from the decompression. Raises: zlib.error: if a decompression error occurred. """ if unpacked.decomp_len is None or unpacked.decomp_len <= -1: raise ValueError("non-negative zlib data stream size expected") decomp_obj = zlib.decompressobj() comp_chunks = [] decomp_chunks = unpacked.decomp_chunks decomp_len = 0 crc32 = unpacked.crc32 max_decomp = unpacked.decomp_len while True: add = read_some(buffer_size) if not add: raise zlib.error("EOF before end of zlib stream") comp_chunks.append(add) # +1 so overrun surfaces as unconsumed_tail rather than being truncated. remaining = max_decomp - decomp_len + 1 decomp = decomp_obj.decompress(add, remaining) if decomp_obj.unconsumed_tail: raise zlib.error("decompressed data exceeds expected size") decomp_len += len(decomp) decomp_chunks.append(decomp) unused = decomp_obj.unused_data if unused: left = len(unused) if crc32 is not None: crc32 = binascii.crc32(add[:-left], crc32) if include_comp: comp_chunks[-1] = add[:-left] break elif crc32 is not None: crc32 = binascii.crc32(add, crc32) if crc32 is not None: crc32 &= 0xFFFFFFFF if decomp_len != unpacked.decomp_len: raise zlib.error("decompressed data does not match expected size") unpacked.crc32 = crc32 if include_comp: unpacked.comp_chunks = comp_chunks return unused def read_zlib_chunks_at( contents: "bytes | mmap.mmap", offset: int, unpacked: UnpackedObject, include_comp: bool = False, buffer_size: int = _ZLIB_BUFSIZE, ) -> int: """Read zlib data from a buffer at a given offset. Like :func:`read_zlib_chunks`, but indexes the buffer directly instead of consuming a read callable, so concurrent readers do not share a position. The buffer is fed to zlib in ``buffer_size`` slices rather than in one piece. That bounds ``unused_data``, which zlib materialises as a copy of everything it was handed past the end of the stream: passing the whole mapping would copy the entire remainder of the pack for every object read. Slices are taken as memoryviews, so the compressed data is decompressed straight out of the mapping. With ``include_comp`` the chunks are kept on ``unpacked`` and outlive the mapping, so those are copied. Args: contents: Buffer holding the compressed data. offset: Offset in contents at which the zlib stream starts. unpacked: An UnpackedObject to write result data to; see :func:`read_zlib_chunks` for the attributes set on it. include_comp: If True, include compressed data in the result. buffer_size: Number of bytes to feed to zlib at a time. Returns: Offset in contents just past the end of the zlib stream. Raises: zlib.error: if a decompression error occurred. """ if unpacked.decomp_len is None or unpacked.decomp_len <= -1: raise ValueError("non-negative zlib data stream size expected") decomp_obj = zlib.decompressobj() comp_chunks = [] decomp_chunks = unpacked.decomp_chunks decomp_len = 0 crc32 = unpacked.crc32 max_decomp = unpacked.decomp_len pos = offset with memoryview(contents) as view: while True: add = view[pos : pos + buffer_size] if not add: raise zlib.error("EOF before end of zlib stream") pos += len(add) # +1 so overrun surfaces as unconsumed_tail rather than being truncated. remaining = max_decomp - decomp_len + 1 decomp = decomp_obj.decompress(add, remaining) if decomp_obj.unconsumed_tail: raise zlib.error("decompressed data exceeds expected size") decomp_len += len(decomp) decomp_chunks.append(decomp) unused = decomp_obj.unused_data if unused: left = len(unused) pos -= left add = add[:-left] if crc32 is not None: crc32 = binascii.crc32(add, crc32) if include_comp: comp_chunks.append(bytes(add)) if unused: break if crc32 is not None: crc32 &= 0xFFFFFFFF if decomp_len != unpacked.decomp_len: raise zlib.error("decompressed data does not match expected size") unpacked.crc32 = crc32 if include_comp: unpacked.comp_chunks = comp_chunks return pos def iter_sha1(iter: Iterable[bytes]) -> bytes: """Return the hexdigest of the SHA1 over a set of names. Args: iter: Iterator over string objects Returns: 40-byte hex sha1 digest """ sha = sha1() for name in iter: sha.update(name) return sha.hexdigest().encode("ascii") def load_pack_index( path: str | os.PathLike[str], object_format: ObjectFormat ) -> "PackIndex": """Load an index file by path. Args: path: Path to the index file object_format: Hash algorithm used by the repository Returns: A PackIndex loaded from the given path """ # Ownership of the file is transferred to the returned index, which mmaps # it and closes it in PackIndex.close(). It must not be closed here: on # Windows an mmap keeps the file locked, so closing the handle out from # under a live mapping leaves the .idx undeletable until the index is GCed. f = GitFile(path, "rb") try: return load_pack_index_file(path, f, object_format) except BaseException: f.close() raise def _load_file_contents( f: IO[bytes] | _GitFile, size: int | None = None ) -> tuple[bytes | Any, int]: """Load contents from a file, preferring mmap when possible. Args: f: File-like object to load size: Expected size, or None to determine from file Returns: Tuple of (contents, size) """ # Avoid rolling a SpooledTemporaryFile to disk just to get a descriptor. if getattr(f, "_rolled", True) is False: fd = None else: try: fd = f.fileno() except (UnsupportedOperation, AttributeError): fd = None # Attempt to use mmap if possible if fd is not None: if size is None: size = os.fstat(fd).st_size if has_mmap: try: contents = mmap.mmap(fd, size, access=mmap.ACCESS_READ) except (OSError, ValueError): # Can't mmap - perhaps a socket or invalid file descriptor pass else: return contents, size contents_bytes = f.read() size = len(contents_bytes) return contents_bytes, size def _close_file_contents(contents: "bytes | mmap.mmap | None") -> None: """Close contents returned by _load_file_contents, if closeable. Callers must close the mapping before the file it maps: on Windows the mapping holds a lock on the file, so the handle cannot be released while it is alive. """ close_fn = getattr(contents, "close", None) if close_fn is not None: close_fn() def load_pack_index_file( path: str | os.PathLike[str], f: IO[bytes] | _GitFile, object_format: ObjectFormat, ) -> "PackIndex": """Load an index file from a file-like object. Args: path: Path for the index file f: File-like object object_format: Hash algorithm used by the repository Returns: A PackIndex loaded from the given file """ contents, size = _load_file_contents(f) if contents[:4] == b"\377tOc": version = struct.unpack(b">L", contents[4:8])[0] if version == 2: return PackIndex2( path, object_format, file=f, contents=contents, size=size, ) elif version == 3: return PackIndex3(path, object_format, file=f, contents=contents, size=size) else: raise KeyError(f"Unknown pack index format {version}") else: return PackIndex1(path, object_format, file=f, contents=contents, size=size) def bisect_find_sha( start: int, end: int, sha: bytes, unpack_name: Callable[[int], bytes] ) -> int | None: """Find a SHA in a data blob with sorted SHAs. Args: start: Start index of range to search end: End index of range to search sha: Sha to find unpack_name: Callback to retrieve SHA by index Returns: Index of the SHA, or None if it wasn't found """ assert start <= end while start <= end: i = (start + end) // 2 file_sha = unpack_name(i) if file_sha < sha: start = i + 1 elif file_sha > sha: end = i - 1 else: return i return None PackIndexEntry = tuple[RawObjectID, int, int | None] class PackIndex: """An index in to a packfile. Given a sha id of an object a pack index can tell you the location in the packfile of that object if it has it. """ object_format: "ObjectFormat" def __eq__(self, other: object) -> bool: """Check equality with another PackIndex.""" if not isinstance(other, PackIndex): return False for (name1, _, _), (name2, _, _) in zip( self.iterentries(), other.iterentries() ): if name1 != name2: return False return True def __ne__(self, other: object) -> bool: """Check if this pack index is not equal to another.""" return not self.__eq__(other) def __len__(self) -> int: """Return the number of entries in this pack index.""" raise NotImplementedError(self.__len__) def __iter__(self) -> Iterator[ObjectID]: """Iterate over the SHAs in this pack.""" return map(lambda sha: sha_to_hex(RawObjectID(sha)), self._itersha()) def iterentries(self) -> Iterator[PackIndexEntry]: """Iterate over the entries in this pack index. Returns: iterator over tuples with object name, offset in packfile and crc32 checksum. """ raise NotImplementedError(self.iterentries) def get_pack_checksum(self) -> bytes | None: """Return the SHA1 checksum stored for the corresponding packfile. Returns: 20-byte binary digest, or None if not available """ raise NotImplementedError(self.get_pack_checksum) def object_offset(self, sha: ObjectID | RawObjectID) -> int: """Return the offset in to the corresponding packfile for the object. Given the name of an object it will return the offset that object lives at within the corresponding pack file. If the pack file doesn't have the object then None will be returned. """ raise NotImplementedError(self.object_offset) def object_sha1(self, index: int) -> bytes: """Return the SHA1 corresponding to the index in the pack file.""" for name, offset, _crc32 in self.iterentries(): if offset == index: return name else: raise KeyError(index) def _object_offset(self, sha: bytes) -> int: """See object_offset. Args: sha: A *binary* SHA string. (20 characters long)_ """ raise NotImplementedError(self._object_offset) def objects_sha1(self) -> bytes: """Return the hex SHA1 over all the shas of all objects in this pack. Note: This is used for the filename of the pack. """ return iter_sha1(self._itersha()) def _itersha(self) -> Iterator[bytes]: """Yield all the SHA1's of the objects in the index, sorted.""" raise NotImplementedError(self._itersha) def iter_prefix(self, prefix: bytes) -> Iterator[RawObjectID]: """Iterate over all SHA1s with the given prefix. Args: prefix: Binary prefix to match Returns: Iterator of matching SHA1s """ # Default implementation for PackIndex classes that don't override for sha, _, _ in self.iterentries(): if sha.startswith(prefix): yield RawObjectID(sha) def close(self) -> None: """Close any open files.""" def check(self) -> None: """Check the consistency of this pack index.""" class MemoryPackIndex(PackIndex): """Pack index that is stored entirely in memory.""" def __init__( self, entries: list[PackIndexEntry], object_format: ObjectFormat, pack_checksum: bytes | None = None, ) -> None: """Create a new MemoryPackIndex. Args: entries: Sequence of name, idx, crc32 (sorted) object_format: Object format used by this index pack_checksum: Optional pack checksum """ self._by_sha = {} self._by_offset = {} for name, offset, _crc32 in entries: self._by_sha[name] = offset self._by_offset[offset] = name self._entries = entries self._pack_checksum = pack_checksum self.object_format = object_format def get_pack_checksum(self) -> bytes | None: """Return the SHA checksum stored for the corresponding packfile.""" return self._pack_checksum def __len__(self) -> int: """Return the number of entries in this pack index.""" return len(self._entries) def object_offset(self, sha: ObjectID | RawObjectID) -> int: """Return the offset for the given SHA. Args: sha: SHA to look up (binary or hex) Returns: Offset in the pack file """ lookup_sha: RawObjectID if len(sha) == self.object_format.hex_length: lookup_sha = hex_to_sha(ObjectID(sha)) else: lookup_sha = RawObjectID(sha) return self._by_sha[lookup_sha] def object_sha1(self, index: int) -> bytes: """Return the SHA1 for the object at the given offset.""" return self._by_offset[index] def _itersha(self) -> Iterator[bytes]: """Iterate over all SHA1s in the index.""" return iter(self._by_sha) def iterentries(self) -> Iterator[PackIndexEntry]: """Iterate over all index entries.""" return iter(self._entries) @classmethod def for_pack(cls, pack_data: "PackData") -> "MemoryPackIndex": """Create a MemoryPackIndex from a PackData object.""" return MemoryPackIndex( list(pack_data.sorted_entries()), pack_checksum=pack_data.get_stored_checksum(), object_format=pack_data.object_format, ) @classmethod def clone(cls, other_index: "PackIndex") -> "MemoryPackIndex": """Create a copy of another PackIndex in memory.""" return cls( list(other_index.iterentries()), other_index.object_format, other_index.get_pack_checksum(), ) class FilePackIndex(PackIndex): """Pack index that is based on a file. To do the loop it opens the file, and indexes first 256 4 byte groups with the first byte of the sha id. The value in the four byte group indexed is the end of the group that shares the same starting byte. Subtract one from the starting byte and index again to find the start of the group. The values are sorted by sha id within the group, so do the math to find the start and end offset and then bisect in to find if the value is present. """ _fan_out_table: list[int] _file: IO[bytes] | _GitFile def __init__( self, filename: str | os.PathLike[str], file: IO[bytes] | _GitFile | None = None, contents: "bytes | mmap.mmap | None" = None, size: int | None = None, ) -> None: """Create a pack index object. Provide it with the name of the index file to consider, and it will map it whenever required. """ self._filename = filename # Take the size now, so it can be checked each time we map the file to # ensure that it hasn't changed. if file is None: self._file = GitFile(filename, "rb") else: self._file = file if contents is None: self._contents, self._size = _load_file_contents(self._file, size) else: self._contents = contents self._size = size if size is not None else len(contents) @property def path(self) -> str: """Return the path to this index file.""" return os.fspath(self._filename) def __eq__(self, other: object) -> bool: """Check equality with another FilePackIndex.""" # Quick optimization: if ( isinstance(other, FilePackIndex) and self._fan_out_table != other._fan_out_table ): return False return super().__eq__(other) def close(self) -> None: """Close the underlying file and any mmap.""" _close_file_contents(self._contents) self._file.close() def __del__(self) -> None: """Ensure the file and mmap are closed when GCed.""" if not getattr(self._file, "closed", True): import warnings warnings.warn( f"unclosed pack index {self!r}", ResourceWarning, stacklevel=2, source=self, ) try: self.close() except Exception: # Ignore errors during cleanup pass def __enter__(self) -> Self: """Enter context manager.""" return self def __exit__( self, type: type | None, value: BaseException | None, traceback: TracebackType | None, ) -> None: """Exit context manager.""" self.close() def __len__(self) -> int: """Return the number of entries in this pack index.""" return self._fan_out_table[-1] def _unpack_entry(self, i: int) -> PackIndexEntry: """Unpack the i-th entry in the index file. Returns: Tuple with object name (SHA), offset in pack file and CRC32 checksum (if known). """ raise NotImplementedError(self._unpack_entry) def _unpack_name(self, i: int) -> bytes: """Unpack the i-th name from the index file.""" raise NotImplementedError(self._unpack_name) def _unpack_offset(self, i: int) -> int: """Unpack the i-th object offset from the index file.""" raise NotImplementedError(self._unpack_offset) def _unpack_crc32_checksum(self, i: int) -> int | None: """Unpack the crc32 checksum for the i-th object from the index file.""" raise NotImplementedError(self._unpack_crc32_checksum) def _itersha(self) -> Iterator[bytes]: """Iterate over all SHA1s in the index.""" for i in range(len(self)): yield self._unpack_name(i) def iterentries(self) -> Iterator[PackIndexEntry]: """Iterate over the entries in this pack index. Returns: iterator over tuples with object name, offset in packfile and crc32 checksum. """ for i in range(len(self)): yield self._unpack_entry(i) def _read_fan_out_table(self, start_offset: int) -> list[int]: """Read the fan-out table from the index. The fan-out table contains 256 entries mapping first byte values to the number of objects with SHA1s less than or equal to that byte. Args: start_offset: Offset in the file where the fan-out table starts Returns: List of 256 integers """ ret = [] for i in range(0x100): fanout_entry = self._contents[ start_offset + i * 4 : start_offset + (i + 1) * 4 ] ret.append(struct.unpack(">L", fanout_entry)[0]) return ret def check(self) -> None: """Check that the stored checksum matches the actual checksum.""" actual = self.calculate_checksum() stored = self.get_stored_checksum() if actual != stored: raise ChecksumMismatch(stored, actual) def calculate_checksum(self) -> bytes: """Calculate the SHA1 checksum over this pack index. Returns: This is a 20-byte binary digest """ return sha1(self._contents[:-20]).digest() def get_pack_checksum(self) -> bytes: """Return the SHA1 checksum stored for the corresponding packfile. Returns: 20-byte binary digest """ return bytes(self._contents[-40:-20]) def get_stored_checksum(self) -> bytes: """Return the SHA1 checksum stored for this index. Returns: 20-byte binary digest """ return bytes(self._contents[-20:]) def object_offset(self, sha: ObjectID | RawObjectID) -> int: """Return the offset in to the corresponding packfile for the object. Given the name of an object it will return the offset that object lives at within the corresponding pack file. If the pack file doesn't have the object then None will be returned. """ lookup_sha: RawObjectID if len(sha) == self.object_format.hex_length: # hex string lookup_sha = hex_to_sha(ObjectID(sha)) else: lookup_sha = RawObjectID(sha) try: return self._object_offset(lookup_sha) except ValueError as exc: closed = getattr(self._contents, "closed", None) if closed in (None, True): raise PackFileDisappeared(self) from exc raise def _object_offset(self, sha: bytes) -> int: """See object_offset. Args: sha: A *binary* SHA string. (20 characters long)_ """ hash_size = getattr(self, "hash_size", 20) # Default to SHA1 for v1 assert len(sha) == hash_size idx = ord(sha[:1]) if idx == 0: start = 0 else: start = self._fan_out_table[idx - 1] end = self._fan_out_table[idx] i = bisect_find_sha(start, end, sha, self._unpack_name) if i is None: raise KeyError(sha) return self._unpack_offset(i) def iter_prefix(self, prefix: bytes) -> Iterator[RawObjectID]: """Iterate over all SHA1s with the given prefix.""" start = ord(prefix[:1]) if start == 0: start = 0 else: start = self._fan_out_table[start - 1] end = ord(prefix[:1]) + 1 if end == 0x100: end = len(self) else: end = self._fan_out_table[end] assert start <= end started = False for i in range(start, end): name: bytes = self._unpack_name(i) if name.startswith(prefix): yield RawObjectID(name) started = True elif started: break class PackIndex1(FilePackIndex): """Version 1 Pack Index file.""" object_format = SHA1 def __init__( self, filename: str | os.PathLike[str], object_format: ObjectFormat, file: IO[bytes] | _GitFile | None = None, contents: bytes | None = None, size: int | None = None, ) -> None: """Initialize a version 1 pack index. Args: filename: Path to the index file object_format: Object format used by the repository file: Optional file object contents: Optional mmap'd contents size: Optional size of the index """ super().__init__(filename, file, contents, size) # PackIndex1 only supports SHA1 if object_format != SHA1: raise AssertionError( f"PackIndex1 only supports SHA1, not {object_format.name}" ) self.object_format = object_format self.version = 1 self._fan_out_table = self._read_fan_out_table(0) self.hash_size = self.object_format.oid_length self._entry_size = 4 + self.hash_size def _unpack_entry(self, i: int) -> tuple[RawObjectID, int, None]: base_offset = (0x100 * 4) + (i * self._entry_size) offset = unpack_from(">L", self._contents, base_offset)[0] name = self._contents[base_offset + 4 : base_offset + 4 + self.hash_size] return (RawObjectID(name), offset, None) def _unpack_name(self, i: int) -> bytes: offset = (0x100 * 4) + (i * self._entry_size) + 4 return self._contents[offset : offset + self.hash_size] def _unpack_offset(self, i: int) -> int: offset = (0x100 * 4) + (i * self._entry_size) return int(unpack_from(">L", self._contents, offset)[0]) def _unpack_crc32_checksum(self, i: int) -> None: # Not stored in v1 index files return None class PackIndex2(FilePackIndex): """Version 2 Pack Index file.""" object_format = SHA1 def __init__( self, filename: str | os.PathLike[str], object_format: ObjectFormat, file: IO[bytes] | _GitFile | None = None, contents: bytes | None = None, size: int | None = None, ) -> None: """Initialize a version 2 pack index. Args: filename: Path to the index file object_format: Object format used by the repository file: Optional file object contents: Optional mmap'd contents size: Optional size of the index """ super().__init__(filename, file, contents, size) self.object_format = object_format if self._contents[:4] != b"\377tOc": raise AssertionError("Not a v2 pack index file") (self.version,) = unpack_from(b">L", self._contents, 4) if self.version != 2: raise AssertionError(f"Version was {self.version}") self._fan_out_table = self._read_fan_out_table(8) self.hash_size = self.object_format.oid_length self._name_table_offset = 8 + 0x100 * 4 self._crc32_table_offset = self._name_table_offset + self.hash_size * len(self) self._pack_offset_table_offset = self._crc32_table_offset + 4 * len(self) self._pack_offset_largetable_offset = self._pack_offset_table_offset + 4 * len( self ) def _unpack_entry(self, i: int) -> tuple[RawObjectID, int, int]: return ( RawObjectID(self._unpack_name(i)), self._unpack_offset(i), self._unpack_crc32_checksum(i), ) def _unpack_name(self, i: int) -> bytes: offset = self._name_table_offset + i * self.hash_size return self._contents[offset : offset + self.hash_size] def _unpack_offset(self, i: int) -> int: offset = self._pack_offset_table_offset + i * 4 offset_val = int(unpack_from(">L", self._contents, offset)[0]) if offset_val & (2**31): offset = ( self._pack_offset_largetable_offset + (offset_val & (2**31 - 1)) * 8 ) offset_val = int(unpack_from(">Q", self._contents, offset)[0]) return offset_val def _unpack_crc32_checksum(self, i: int) -> int: return int( unpack_from(">L", self._contents, self._crc32_table_offset + i * 4)[0] ) def get_pack_checksum(self) -> bytes: """Return the checksum stored for the corresponding packfile. Returns: binary digest (size depends on hash algorithm) """ # Index ends with: pack_checksum + index_checksum # Each checksum is hash_size bytes checksum_size = self.hash_size return bytes(self._contents[-2 * checksum_size : -checksum_size]) def get_stored_checksum(self) -> bytes: """Return the checksum stored for this index. Returns: binary digest (size depends on hash algorithm) """ checksum_size = self.hash_size return bytes(self._contents[-checksum_size:]) def calculate_checksum(self) -> bytes: """Calculate the checksum over this pack index. Returns: binary digest (size depends on hash algorithm) """ # Determine hash function based on hash_size if self.hash_size == 20: hash_func = sha1 elif self.hash_size == 32: hash_func = sha256 else: raise ValueError(f"Unsupported hash size: {self.hash_size}") return hash_func(self._contents[: -self.hash_size]).digest() class PackIndex3(FilePackIndex): """Version 3 Pack Index file. Supports variable hash sizes for SHA-1 (20 bytes) and SHA-256 (32 bytes). """ def __init__( self, filename: str | os.PathLike[str], object_format: ObjectFormat, file: IO[bytes] | _GitFile | None = None, contents: bytes | None = None, size: int | None = None, ) -> None: """Initialize a version 3 pack index. Args: filename: Path to the index file object_format: Object format used by the repository file: Optional file object contents: Optional mmap'd contents size: Optional size of the index """ super().__init__(filename, file, contents, size) if self._contents[:4] != b"\377tOc": raise AssertionError("Not a v3 pack index file") (self.version,) = unpack_from(b">L", self._contents, 4) if self.version != 3: raise AssertionError(f"Version was {self.version}") # Read hash algorithm identifier (1 = SHA-1, 2 = SHA-256) (self.hash_format,) = unpack_from(b">L", self._contents, 8) file_object_format = OBJECT_FORMAT_TYPE_NUMS[self.hash_format] # Verify provided object_format matches what's in the file if object_format != file_object_format: raise AssertionError( f"Object format mismatch: provided {object_format.name}, " f"but file contains {file_object_format.name}" ) self.object_format = object_format self.hash_size = self.object_format.oid_length # Read length of shortened object names (self.shortened_oid_len,) = unpack_from(b">L", self._contents, 12) # Calculate offsets based on variable hash size self._fan_out_table = self._read_fan_out_table( 16 ) # After header (4 + 4 + 4 + 4) self._name_table_offset = 16 + 0x100 * 4 self._crc32_table_offset = self._name_table_offset + self.hash_size * len(self) self._pack_offset_table_offset = self._crc32_table_offset + 4 * len(self) self._pack_offset_largetable_offset = self._pack_offset_table_offset + 4 * len( self ) def _unpack_entry(self, i: int) -> tuple[RawObjectID, int, int]: return ( RawObjectID(self._unpack_name(i)), self._unpack_offset(i), self._unpack_crc32_checksum(i), ) def _unpack_name(self, i: int) -> bytes: offset = self._name_table_offset + i * self.hash_size return self._contents[offset : offset + self.hash_size] def _unpack_offset(self, i: int) -> int: offset_pos = self._pack_offset_table_offset + i * 4 offset = unpack_from(">L", self._contents, offset_pos)[0] assert isinstance(offset, int) if offset & (2**31): large_offset_pos = ( self._pack_offset_largetable_offset + (offset & (2**31 - 1)) * 8 ) offset = unpack_from(">Q", self._contents, large_offset_pos)[0] assert isinstance(offset, int) return offset def _unpack_crc32_checksum(self, i: int) -> int: result = unpack_from(">L", self._contents, self._crc32_table_offset + i * 4)[0] assert isinstance(result, int) return result def read_pack_header_at( contents: "bytes | mmap.mmap", offset: int = 0 ) -> tuple[int, int]: """Read the header of a pack file from a buffer. Args: contents: Buffer holding the pack offset: Offset in contents at which the header starts Returns: Tuple of (pack version, number of objects). """ header = contents[offset : offset + 12] if not header: raise AssertionError("file too short to contain pack") if header[:4] != b"PACK": raise AssertionError(f"Invalid pack header {bytes(header)!r}") (version,) = unpack_from(b">L", header, 4) if version not in (2, 3): raise AssertionError(f"Version was {version}") (num_objects,) = unpack_from(b">L", header, 8) return (version, num_objects) def read_pack_header(read: Callable[[int], bytes]) -> tuple[int, int]: """Read the header of a pack file. Args: read: Read function Returns: Tuple of (pack version, number of objects). """ return read_pack_header_at(read(12)) def chunks_length(chunks: bytes | Iterable[bytes]) -> int: """Get the total length of a sequence of chunks. Args: chunks: Either a single bytes object or an iterable of bytes Returns: Total length in bytes """ if isinstance(chunks, bytes): return len(chunks) else: return sum(map(len, chunks)) def _decode_object_header(raw: list[int]) -> tuple[int, int]: """Decode an object type and size from a pack object header.""" type_num = (raw[0] >> 4) & 0x07 size = raw[0] & 0x0F for i, byte in enumerate(raw[1:]): size += (byte & 0x7F) << ((i * 7) + 4) return type_num, size def _decode_delta_base_offset(raw: list[int]) -> int: """Decode an OFS_DELTA base offset from its variable-length encoding.""" if raw[-1] & 0x80: raise AssertionError delta_base_offset = raw[0] & 0x7F for byte in raw[1:]: delta_base_offset += 1 delta_base_offset <<= 7 delta_base_offset += byte & 0x7F if delta_base_offset == 0: # A zero offset makes the delta reference itself, which would # loop forever in resolve_object. git's C client rejects this # with "delta offset == 0 is invalid". raise ApplyDeltaError("OFS_DELTA has delta_base_offset of 0") return delta_base_offset def unpack_object( read_all: Callable[[int], bytes], hash_func: Callable[[], "HashObject"], read_some: Callable[[int], bytes] | None = None, compute_crc32: bool = False, include_comp: bool = False, zlib_bufsize: int = _ZLIB_BUFSIZE, ) -> tuple[UnpackedObject, bytes]: """Unpack a Git object. Args: read_all: Read function that blocks until the number of requested bytes are read. hash_func: Hash function to use for computing object IDs. read_some: Read function that returns at least one byte, but may not return the number of bytes requested. compute_crc32: If True, compute the CRC32 of the compressed data. If False, the returned CRC32 will be None. include_comp: If True, include compressed data in the result. zlib_bufsize: An optional buffer size for zlib operations. Returns: A tuple of (unpacked, unused), where unused is the unused data leftover from decompression, and unpacked in an UnpackedObject with the following attrs set: * obj_chunks (for non-delta types) * pack_type_num * delta_base (for delta types) * comp_chunks (if include_comp is True) * decomp_chunks * decomp_len * crc32 (if compute_crc32 is True) """ if read_some is None: read_some = read_all if compute_crc32: crc32 = 0 else: crc32 = None raw, crc32 = take_msb_bytes(read_all, crc32=crc32) type_num, size = _decode_object_header(raw) delta_base: int | bytes | None raw_base = len(raw) if type_num == OFS_DELTA: raw, crc32 = take_msb_bytes(read_all, crc32=crc32) raw_base += len(raw) delta_base = _decode_delta_base_offset(raw) elif type_num == REF_DELTA: # Determine hash size from hash_func hash_size = len(hash_func().digest()) delta_base_obj = read_all(hash_size) if crc32 is not None: crc32 = binascii.crc32(delta_base_obj, crc32) delta_base = delta_base_obj raw_base += hash_size else: delta_base = None unpacked = UnpackedObject( type_num, delta_base=delta_base, decomp_len=size, crc32=crc32, hash_func=hash_func, ) unused = read_zlib_chunks( read_some, unpacked, buffer_size=zlib_bufsize, include_comp=include_comp, ) return unpacked, unused def unpack_object_at( contents: "bytes | mmap.mmap", offset: int, hash_func: Callable[[], "HashObject"], compute_crc32: bool = False, include_comp: bool = False, zlib_bufsize: int = _ZLIB_BUFSIZE, ) -> tuple[UnpackedObject, int]: """Unpack a Git object from a buffer at a given offset. Like :func:`unpack_object`, but indexes the buffer directly rather than consuming a read callable, so any number of readers can work on the same buffer concurrently. Args: contents: Buffer holding the pack. offset: Offset in contents at which the object starts. hash_func: Hash function to use for computing object IDs. compute_crc32: If True, compute the CRC32 of the compressed data. include_comp: If True, include compressed data in the result. zlib_bufsize: An optional buffer size for zlib operations. Returns: A tuple of (unpacked, end), where end is the offset just past the object and unpacked is an UnpackedObject with its ``offset`` set; see :func:`unpack_object` for the other attributes. """ crc32: int | None = 0 if compute_crc32 else None raw, pos, crc32 = take_msb_bytes_at(contents, offset, crc32=crc32) type_num, size = _decode_object_header(raw) delta_base: int | bytes | None if type_num == OFS_DELTA: raw, pos, crc32 = take_msb_bytes_at(contents, pos, crc32=crc32) delta_base = _decode_delta_base_offset(raw) elif type_num == REF_DELTA: hash_size = len(hash_func().digest()) delta_base_obj = bytes(contents[pos : pos + hash_size]) if len(delta_base_obj) != hash_size: raise AssertionError(f"unexpected end of pack data at {pos}") pos += hash_size if crc32 is not None: crc32 = binascii.crc32(delta_base_obj, crc32) delta_base = delta_base_obj else: delta_base = None unpacked = UnpackedObject( type_num, delta_base=delta_base, decomp_len=size, crc32=crc32, hash_func=hash_func, ) unpacked.offset = offset end = read_zlib_chunks_at( contents, pos, unpacked, buffer_size=zlib_bufsize, include_comp=include_comp, ) return unpacked, end def _compute_object_size(value: tuple[int, Any]) -> int: """Compute the size of a unresolved object for use with LRUSizeCache.""" (num, obj) = value if num in DELTA_TYPES: return chunks_length(obj[1]) return chunks_length(obj) class PackStreamReader: """Class to read a pack stream. The pack is read from a ReceivableProtocol using read() or recv() as appropriate. """ def __init__( self, hash_func: Callable[[], "HashObject"], read_all: Callable[[int], bytes], read_some: Callable[[int], bytes] | None = None, zlib_bufsize: int = _ZLIB_BUFSIZE, ) -> None: """Initialize pack stream reader. Args: hash_func: Hash function to use for computing object IDs read_all: Function to read all requested bytes read_some: Function to read some bytes (optional) zlib_bufsize: Buffer size for zlib decompression """ self.read_all = read_all if read_some is None: self.read_some = read_all else: self.read_some = read_some self.hash_func = hash_func self.sha = hash_func() self._hash_size = len(hash_func().digest()) self._offset = 0 self._rbuf = BytesIO() # trailer is a deque to avoid memory allocation on small reads self._trailer: deque[int] = deque() self._zlib_bufsize = zlib_bufsize def _read(self, read: Callable[[int], bytes], size: int) -> bytes: """Read up to size bytes using the given callback. As a side effect, update the verifier's hash (excluding the last hash_size bytes read, which is the pack checksum). Args: read: The read callback to read from. size: The maximum number of bytes to read; the particular behavior is callback-specific. Returns: Bytes read """ data = read(size) # maintain a trailer of the last hash_size bytes we've read n = len(data) self._offset += n tn = len(self._trailer) if n >= self._hash_size: to_pop = tn to_add = self._hash_size else: to_pop = max(n + tn - self._hash_size, 0) to_add = n self.sha.update( bytes(bytearray([self._trailer.popleft() for _ in range(to_pop)])) ) self._trailer.extend(data[-to_add:]) # hash everything but the trailer self.sha.update(data[:-to_add]) return data def _buf_len(self) -> int: buf = self._rbuf start = buf.tell() buf.seek(0, SEEK_END) end = buf.tell() buf.seek(start) return end - start @property def offset(self) -> int: """Return current offset in the stream.""" return self._offset - self._buf_len() def read(self, size: int) -> bytes: """Read, blocking until size bytes are read.""" buf_len = self._buf_len() if buf_len >= size: return self._rbuf.read(size) buf_data = self._rbuf.read() self._rbuf = BytesIO() return buf_data + self._read(self.read_all, size - buf_len) def recv(self, size: int) -> bytes: """Read up to size bytes, blocking until one byte is read.""" buf_len = self._buf_len() if buf_len: data = self._rbuf.read(size) if size >= buf_len: self._rbuf = BytesIO() return data return self._read(self.read_some, size) def __len__(self) -> int: """Return the number of objects in this pack.""" return self._num_objects def read_objects(self, compute_crc32: bool = False) -> Iterator[UnpackedObject]: """Read the objects in this pack file. Args: compute_crc32: If True, compute the CRC32 of the compressed data. If False, the returned CRC32 will be None. Returns: Iterator over UnpackedObjects with the following members set: offset obj_type_num obj_chunks (for non-delta types) delta_base (for delta types) decomp_chunks decomp_len crc32 (if compute_crc32 is True) Raises: ChecksumMismatch: if the checksum of the pack contents does not match the checksum in the pack trailer. zlib.error: if an error occurred during zlib decompression. IOError: if an error occurred writing to the output file. """ _pack_version, self._num_objects = read_pack_header(self.read) for _ in range(self._num_objects): offset = self.offset unpacked, unused = unpack_object( self.read, self.hash_func, read_some=self.recv, compute_crc32=compute_crc32, zlib_bufsize=self._zlib_bufsize, ) unpacked.offset = offset # prepend any unused data to current read buffer buf = BytesIO() buf.write(unused) buf.write(self._rbuf.read()) buf.seek(0) self._rbuf = buf yield unpacked if self._buf_len() < self._hash_size: # If the read buffer is full, then the last read() got the whole # trailer off the wire. If not, it means there is still some of the # trailer to read. We need to read() all hash_size bytes; N come from the # read buffer and (hash_size - N) come from the wire. self.read(self._hash_size) pack_sha = bytearray(self._trailer) if pack_sha != self.sha.digest(): raise ChecksumMismatch( sha_to_hex(RawObjectID(bytes(pack_sha))), self.sha.hexdigest() ) class PackStreamCopier(PackStreamReader): """Class to verify a pack stream as it is being read. The pack is read from a ReceivableProtocol using read() or recv() as appropriate and written out to the given file-like object. """ def __init__( self, hash_func: Callable[[], "HashObject"], read_all: Callable[[int], bytes], read_some: Callable[[int], bytes] | None, outfile: IO[bytes], delta_iter: "DeltaChainIterator[UnpackedObject] | None" = None, ) -> None: """Initialize the copier. Args: hash_func: Hash function to use for computing object IDs read_all: Read function that blocks until the number of requested bytes are read. read_some: Read function that returns at least one byte, but may not return the number of bytes requested. outfile: File-like object to write output through. delta_iter: Optional DeltaChainIterator to record deltas as we read them. """ super().__init__(hash_func, read_all, read_some=read_some) self.outfile = outfile self._delta_iter = delta_iter def _read(self, read: Callable[[int], bytes], size: int) -> bytes: """Read data from the read callback and write it to the file.""" data = super()._read(read, size) self.outfile.write(data) return data def verify(self, progress: Callable[..., None] | None = None) -> None: """Verify a pack stream and write it to the output file. See PackStreamReader.iterobjects for a list of exceptions this may throw. """ i = 0 # default count of entries if read_objects() is empty for i, unpacked in enumerate(self.read_objects()): if self._delta_iter: self._delta_iter.record(unpacked) if progress is not None: progress(f"copying pack entries: {i}/{len(self)}\r".encode("ascii")) if progress is not None: progress(f"copied {i} pack entries\n".encode("ascii")) def obj_sha( type: int, chunks: bytes | Iterable[bytes], hash_func: Callable[[], "HashObject"] = sha1, ) -> bytes: """Compute the SHA for a numeric type and object chunks. Args: type: Object type number chunks: Object data chunks hash_func: Hash function to use (defaults to sha1) Returns: Binary hash digest """ sha = hash_func() sha.update(object_header(type, chunks_length(chunks))) if isinstance(chunks, bytes): sha.update(chunks) else: for chunk in chunks: sha.update(chunk) return sha.digest() def compute_file_sha( f: IO[bytes], hash_func: Callable[[], "HashObject"], start_ofs: int = 0, end_ofs: int = 0, buffer_size: int = 1 << 16, ) -> "HashObject": """Hash a portion of a file into a new SHA. Args: f: A file-like object to read from that supports seek(). hash_func: A callable that returns a new HashObject. start_ofs: The offset in the file to start reading at. end_ofs: The offset in the file to end reading at, relative to the end of the file. buffer_size: A buffer size for reading. Returns: A new SHA object updated with data read from the file. """ sha = hash_func() f.seek(0, SEEK_END) length = f.tell() if start_ofs < 0: raise AssertionError(f"start_ofs cannot be negative: {start_ofs}") if (end_ofs < 0 and length + end_ofs < start_ofs) or end_ofs > length: raise AssertionError( f"Attempt to read beyond file length. start_ofs: {start_ofs}, end_ofs: {end_ofs}, file length: {length}" ) todo = length + end_ofs - start_ofs f.seek(start_ofs) while todo: data = f.read(min(todo, buffer_size)) sha.update(data) todo -= len(data) return sha def compute_buffer_sha( contents: "bytes | mmap.mmap", hash_func: Callable[[], "HashObject"], start_ofs: int = 0, end_ofs: int = 0, ) -> "HashObject": """Hash a portion of a buffer into a new SHA. The region is hashed in one pass through a memoryview, so a mapped pack is never copied. The view is released before returning rather than left to the garbage collector, since ``mmap.close()`` raises BufferError while an export is alive. Args: contents: Buffer to hash. hash_func: A callable that returns a new HashObject. start_ofs: The offset in the buffer to start hashing at. end_ofs: The offset to end hashing at, relative to the end of the buffer. Returns: A new SHA object updated with data read from the buffer. """ sha = hash_func() length = len(contents) if start_ofs < 0: raise AssertionError(f"start_ofs cannot be negative: {start_ofs}") if (end_ofs < 0 and length + end_ofs < start_ofs) or end_ofs > length: raise AssertionError( f"Attempt to read beyond buffer length. start_ofs: {start_ofs}, end_ofs: {end_ofs}, buffer length: {length}" ) with memoryview(contents) as view: sha.update(view[start_ofs : length + end_ofs]) return sha class PackData: """The data contained in a packfile. Pack files can be accessed both sequentially for exploding a pack, and directly with the help of an index to retrieve a specific object. The objects within are either complete or a delta against another. The header is variable length. If the MSB of each byte is set then it indicates that the subsequent byte is still part of the header. For the first byte the next MS bits are the type, which tells you the type of object, and whether it is a delta. The LS byte is the lowest bits of the size. For each subsequent byte the LS 7 bits are the next MS bits of the size, i.e. the last byte of the header contains the MS bits of the size. For the complete objects the data is stored as zlib deflated data. The size in the header is the uncompressed object size, so to uncompress you need to just keep feeding data to zlib until you get an object back, or it errors on bad data. This is done here by reading from the mapped pack contents starting at the deflated object. Currently there are no integrity checks done. Also no attempt is made to try and detect the delta case, or a request for an object at the wrong position. It will all just throw a zlib or KeyError. """ def __init__( self, filename: str | os.PathLike[str], object_format: ObjectFormat, file: IO[bytes] | None = None, size: int | None = None, *, delta_window_size: int | None = None, window_memory: int | None = None, delta_cache_size: int | None = None, depth: int | None = None, threads: int | None = None, big_file_threshold: int | None = None, delta_base_cache_limit: int | None = None, ) -> None: """Create a PackData object representing the pack in the given filename. The file must exist and stay readable until the object is disposed of. It must also stay the same size. It is mapped into memory on open, so reads index the mapping directly rather than sharing a file position. The size argument is not trusted for checksum offsets, which are derived from the mapped length instead. When given it is checked against that length, so a caller passing a stale size gets an error rather than silently wrong offsets. """ self._filename = filename self.object_format = object_format self._header_size = 12 self.delta_window_size = delta_window_size self.window_memory = window_memory self.delta_cache_size = delta_cache_size self.depth = depth self.threads = threads self.big_file_threshold = big_file_threshold self.delta_base_cache_limit = delta_base_cache_limit self._file: IO[bytes] self._contents: bytes | mmap.mmap | None = None if file is None: self._file = GitFile(self._filename, "rb") self._close_file = True else: # A caller-supplied file stays the caller's to close; it may well # keep writing to it after we are done reading. self._file = file self._close_file = False try: # Map the pack once; every read indexes this buffer at an explicit # offset, so concurrent reads never contend on a file position. self._contents, self._size = _load_file_contents(self._file) if size is not None and size != self._size: raise AssertionError( f"{self._filename} is {self._size} bytes, but caller said {size}" ) minimum_size = self._header_size + self.object_format.oid_length if self._size < minimum_size: raise AssertionError( f"{self._filename} is too small for a packfile ({self._size} < {minimum_size})" ) (_version, self._num_objects) = read_pack_header_at(self._contents) # Use delta_base_cache_limit, then delta_cache_size, then default cache_size = ( delta_base_cache_limit or delta_cache_size or DEFAULT_DELTA_BASE_CACHE_LIMIT ) self._init_offset_cache(cache_size) except BaseException: self.close() raise def _init_offset_cache(self, max_size: int) -> None: """Initialize the resolved object cache.""" self._offset_cache = LRUSizeCache[int, tuple[int, OldUnpackedObject]]( max_size, compute_size=_compute_object_size ) # Cache hits update the LRU linked list, so reads need locking too. self._offset_cache_lock = threading.Lock() @property def filename(self) -> str: """Get the filename of the pack file. Returns: Base filename without directory path """ return os.path.basename(self._filename) @property def path(self) -> str | os.PathLike[str]: """Get the full path of the pack file. Returns: Full path to the pack file """ return self._filename @classmethod def from_file( cls, file: IO[bytes], object_format: ObjectFormat, size: int | None = None, ) -> "PackData": """Create a PackData object from an open file. Args: file: Open file object object_format: Object format size: Optional expected file size, checked against the mapped length Returns: PackData instance """ return cls(str(file), object_format, file=file, size=size) @classmethod def from_path( cls, path: str | os.PathLike[str], object_format: ObjectFormat, ) -> "PackData": """Create a PackData object from a file path. Args: path: Path to the pack file object_format: Object format Returns: PackData instance """ return cls(filename=path, object_format=object_format) def _buffer(self) -> "bytes | mmap.mmap": """Return the mapped pack contents.""" contents = self._contents if contents is None: raise ValueError(f"read from closed PackData: {self._filename}") return contents def close(self) -> None: """Release the mapping, and the pack file if we opened it. Callers must drop the mapping before writing to or renaming the pack: on Windows a live mapping locks the file. """ contents = self._contents self._contents = None _close_file_contents(contents) if self._file is not None: if self._close_file: self._file.close() self._file = None # type: ignore def __del__(self) -> None: """Ensure pack file is closed when PackData is garbage collected.""" if getattr(self, "_file", None) is not None: import warnings warnings.warn( f"unclosed PackData {self!r}", ResourceWarning, stacklevel=2, source=self, ) try: self.close() except Exception: # Ignore errors during cleanup pass def __enter__(self) -> Self: """Enter context manager.""" return self def __exit__( self, type: type | None, value: BaseException | None, traceback: TracebackType | None, ) -> None: """Exit context manager.""" self.close() def __eq__(self, other: object) -> bool: """Check equality with another object.""" if isinstance(other, PackData): return self.get_stored_checksum() == other.get_stored_checksum() return False def __len__(self) -> int: """Returns the number of objects in this pack.""" return self._num_objects def calculate_checksum(self) -> bytes: """Calculate the checksum for this pack. Returns: Binary digest (size depends on hash algorithm) """ return compute_buffer_sha( self._buffer(), hash_func=self.object_format.hash_func, end_ofs=-self.object_format.oid_length, ).digest() def iter_unpacked(self, *, include_comp: bool = False) -> Iterator[UnpackedObject]: """Iterate over unpacked objects in the pack.""" if self._num_objects is None: return contents = self._buffer() offset = self._header_size for _ in range(self._num_objects): unpacked, offset = unpack_object_at( contents, offset, self.object_format.hash_func, compute_crc32=False, include_comp=include_comp, ) yield unpacked def iterentries( self, progress: Callable[[int, int], None] | None = None, resolve_ext_ref: ResolveExtRefFn | None = None, ) -> Iterator[PackIndexEntry]: """Yield entries summarizing the contents of this pack. Args: progress: Progress function, called with current and total object count. resolve_ext_ref: Optional function to resolve external references Returns: iterator of tuples with (sha, offset, crc32) """ num_objects = self._num_objects indexer = PackIndexer.for_pack_data(self, resolve_ext_ref=resolve_ext_ref) for i, result in enumerate(indexer): if progress is not None: progress(i, num_objects) yield result def sorted_entries( self, progress: Callable[[int, int], None] | None = None, resolve_ext_ref: ResolveExtRefFn | None = None, ) -> list[tuple[RawObjectID, int, int]]: """Return entries in this pack, sorted by SHA. Args: progress: Progress function, called with current and total object count resolve_ext_ref: Optional function to resolve external references Returns: Iterator of tuples with (sha, offset, crc32) """ return sorted( self.iterentries(progress=progress, resolve_ext_ref=resolve_ext_ref) # type: ignore ) def create_index_v1( self, filename: str, progress: Callable[..., None] | None = None, resolve_ext_ref: ResolveExtRefFn | None = None, ) -> bytes: """Create a version 1 file for this data file. Args: filename: Index filename. progress: Progress report function resolve_ext_ref: Optional function to resolve external references Returns: Checksum of index file """ entries = self.sorted_entries( progress=progress, resolve_ext_ref=resolve_ext_ref ) checksum = self.calculate_checksum() with GitFile(filename, "wb") as f: write_pack_index_v1( f, entries, checksum, ) return checksum def create_index_v2( self, filename: str, progress: Callable[..., None] | None = None, resolve_ext_ref: ResolveExtRefFn | None = None, ) -> bytes: """Create a version 2 index file for this data file. Args: filename: Index filename. progress: Progress report function resolve_ext_ref: Optional function to resolve external references Returns: Checksum of index file """ entries = self.sorted_entries( progress=progress, resolve_ext_ref=resolve_ext_ref ) with GitFile(filename, "wb") as f: return write_pack_index_v2(f, entries, self.calculate_checksum()) def create_index_v3( self, filename: str, progress: Callable[..., None] | None = None, resolve_ext_ref: ResolveExtRefFn | None = None, hash_format: int | None = None, ) -> bytes: """Create a version 3 index file for this data file. Args: filename: Index filename. progress: Progress report function resolve_ext_ref: Function to resolve external references hash_format: Hash algorithm identifier (1 = SHA-1, 2 = SHA-256) Returns: Checksum of index file """ entries = self.sorted_entries( progress=progress, resolve_ext_ref=resolve_ext_ref ) with GitFile(filename, "wb") as f: if hash_format is None: hash_format = 1 # Default to SHA-1 return write_pack_index_v3( f, entries, self.calculate_checksum(), hash_format=hash_format ) def create_index( self, filename: str, progress: Callable[..., None] | None = None, version: int = 2, resolve_ext_ref: ResolveExtRefFn | None = None, hash_format: int | None = None, ) -> bytes: """Create an index file for this data file. Args: filename: Index filename. progress: Progress report function version: Index version (1, 2, or 3) resolve_ext_ref: Function to resolve external references hash_format: Hash algorithm identifier for v3 (1 = SHA-1, 2 = SHA-256) Returns: Checksum of index file """ if version == 1: return self.create_index_v1( filename, progress, resolve_ext_ref=resolve_ext_ref ) elif version == 2: return self.create_index_v2( filename, progress, resolve_ext_ref=resolve_ext_ref ) elif version == 3: return self.create_index_v3( filename, progress, resolve_ext_ref=resolve_ext_ref, hash_format=hash_format, ) else: raise ValueError(f"unknown index format {version}") def get_stored_checksum(self) -> bytes: """Return the expected checksum stored in this pack.""" checksum_size = self.object_format.oid_length return bytes(self._buffer()[self._size - checksum_size :]) def check(self) -> None: """Check the consistency of this pack.""" actual = self.calculate_checksum() stored = self.get_stored_checksum() if actual != stored: raise ChecksumMismatch(stored, actual) def get_unpacked_object_at( self, offset: int, *, include_comp: bool = False ) -> UnpackedObject: """Given offset in the packfile return a UnpackedObject.""" assert offset >= self._header_size unpacked, _ = unpack_object_at( self._buffer(), offset, self.object_format.hash_func, include_comp=include_comp, ) return unpacked def _get_cached_object_at(self, offset: int) -> tuple[int, OldUnpackedObject]: """Return the cached object at offset, or raise KeyError.""" # Hot path: acquire/release directly rather than using the context # manager, which measurably speeds up cache hits on get_object_at. self._offset_cache_lock.acquire() try: return self._offset_cache[offset] finally: self._offset_cache_lock.release() def _cache_object_at( self, offset: int, type_num: int, chunks: OldUnpackedObject ) -> None: """Cache a resolved object at offset.""" with self._offset_cache_lock: self._offset_cache[offset] = (type_num, chunks) def get_object_at(self, offset: int) -> tuple[int, OldUnpackedObject]: """Given an offset in to the packfile return the object that is there. Using the associated index the location of an object can be looked up, and then the packfile can be asked directly for that object using this function. """ try: return self._get_cached_object_at(offset) except KeyError: pass unpacked = self.get_unpacked_object_at(offset, include_comp=False) return (unpacked.pack_type_num, unpacked._obj()) T = TypeVar("T") class DeltaChainIterator(Generic[T]): """Abstract iterator over pack data based on delta chains. Each object in the pack is guaranteed to be inflated exactly once, regardless of how many objects reference it as a delta base. As a result, memory usage is proportional to the length of the longest delta chain. Subclasses can override _result to define the result type of the iterator. By default, results are UnpackedObjects with the following members set: * offset * obj_type_num * obj_chunks * pack_type_num * delta_base (for delta types) * comp_chunks (if _include_comp is True) * decomp_chunks * decomp_len * crc32 (if _compute_crc32 is True) """ _compute_crc32 = False _include_comp = False def __init__( self, file_obj: IO[bytes] | None, hash_func: Callable[[], "HashObject"], *, resolve_ext_ref: ResolveExtRefFn | None = None, object_format: "ObjectFormat | None" = None, ) -> None: """Initialize DeltaChainIterator. Args: file_obj: File object to read pack data from hash_func: Hash function to use for computing object IDs resolve_ext_ref: Optional function to resolve external references object_format: Optional object format. Required by subclasses that materialise objects (e.g. PackInflater) when iterating packs in a non-default hash algorithm such as SHA-256. """ self._file = file_obj self._contents: bytes | mmap.mmap | None = None self.hash_func = hash_func self._object_format = object_format self._resolve_ext_ref = resolve_ext_ref self._pending_ofs: dict[int, list[int]] = defaultdict(list) self._pending_ref: dict[bytes, list[int]] = defaultdict(list) self._full_ofs: list[tuple[int, int]] = [] self._ext_refs: list[RawObjectID] = [] @classmethod def for_pack_data( cls, pack_data: PackData, resolve_ext_ref: ResolveExtRefFn | None = None ) -> "DeltaChainIterator[T]": """Create a DeltaChainIterator from pack data. Args: pack_data: PackData object to iterate resolve_ext_ref: Optional function to resolve external refs Returns: DeltaChainIterator instance """ walker = cls( None, pack_data.object_format.hash_func, resolve_ext_ref=resolve_ext_ref, object_format=pack_data.object_format, ) walker.set_pack_data(pack_data) for unpacked in pack_data.iter_unpacked(include_comp=False): walker.record(unpacked) return walker @classmethod def for_pack_subset( cls, pack: "Pack", shas: Iterable[ObjectID | RawObjectID], *, allow_missing: bool = False, resolve_ext_ref: ResolveExtRefFn | None = None, ) -> "DeltaChainIterator[T]": """Create a DeltaChainIterator for a subset of objects. Args: pack: Pack object containing the data shas: Iterable of object SHAs to include allow_missing: If True, skip missing objects resolve_ext_ref: Optional function to resolve external refs Returns: DeltaChainIterator instance """ walker = cls( None, pack.object_format.hash_func, resolve_ext_ref=resolve_ext_ref, object_format=pack.object_format, ) walker.set_pack_data(pack.data) todo = set() for sha in shas: try: off = pack.index.object_offset(sha) except KeyError: if not allow_missing: raise else: todo.add(off) done = set() while todo: off = todo.pop() unpacked = pack.data.get_unpacked_object_at(off) walker.record(unpacked) done.add(off) base_ofs = None if unpacked.pack_type_num == OFS_DELTA: assert unpacked.offset is not None assert unpacked.delta_base is not None assert isinstance(unpacked.delta_base, int) base_ofs = unpacked.offset - unpacked.delta_base elif unpacked.pack_type_num == REF_DELTA: with suppress(KeyError): assert isinstance(unpacked.delta_base, bytes) base_ofs = pack.index.object_offset( RawObjectID(unpacked.delta_base) ) if base_ofs is not None and base_ofs not in done: todo.add(base_ofs) return walker def record(self, unpacked: UnpackedObject) -> None: """Record an unpacked object for later processing. Args: unpacked: UnpackedObject to record """ type_num = unpacked.pack_type_num offset = unpacked.offset assert offset is not None if type_num == OFS_DELTA: assert unpacked.delta_base is not None assert isinstance(unpacked.delta_base, int) base_offset = offset - unpacked.delta_base self._pending_ofs[base_offset].append(offset) elif type_num == REF_DELTA: assert isinstance(unpacked.delta_base, bytes) self._pending_ref[unpacked.delta_base].append(offset) else: self._full_ofs.append((offset, type_num)) def set_pack_data(self, pack_data: PackData) -> None: """Set the pack data for iteration. Args: pack_data: PackData object to use """ self._file = None self._contents = pack_data._buffer() def _walk_all_chains(self) -> Iterator[T]: for offset, type_num in self._full_ofs: yield from self._follow_chain(offset, type_num, None) yield from self._walk_ref_chains() assert not self._pending_ofs, repr(self._pending_ofs) def _ensure_no_pending(self) -> None: if self._pending_ref: raise UnresolvedDeltas( [sha_to_hex(RawObjectID(s)) for s in self._pending_ref] ) def _walk_ref_chains(self) -> Iterator[T]: if not self._resolve_ext_ref: self._ensure_no_pending() return for base_sha, pending in sorted(self._pending_ref.items()): if base_sha not in self._pending_ref: continue try: type_num, chunks = self._resolve_ext_ref(RawObjectID(base_sha)) except KeyError: # Not an external ref, but may depend on one. Either it will # get popped via a _follow_chain call, or we will raise an # error below. continue self._ext_refs.append(RawObjectID(base_sha)) self._pending_ref.pop(base_sha) for new_offset in pending: yield from self._follow_chain(new_offset, type_num, chunks) self._ensure_no_pending() def _result(self, unpacked: UnpackedObject) -> T: raise NotImplementedError def _resolve_object( self, offset: int, obj_type_num: int, base_chunks: bytes | list[bytes] | None, ) -> UnpackedObject: if self._contents is not None: unpacked, _ = unpack_object_at( self._contents, offset, self.hash_func, compute_crc32=self._compute_crc32, include_comp=self._include_comp, ) else: # add_thin_pack may still be writing to this file, so it cannot be # mapped up front; read through the file position instead. assert self._file is not None self._file.seek(offset) unpacked, _ = unpack_object( self._file.read, self.hash_func, read_some=None, compute_crc32=self._compute_crc32, include_comp=self._include_comp, ) unpacked.offset = offset if base_chunks is None: assert unpacked.pack_type_num == obj_type_num else: assert unpacked.pack_type_num in DELTA_TYPES unpacked.obj_type_num = obj_type_num unpacked.obj_chunks = apply_delta(base_chunks, unpacked.decomp_chunks) # A delta that resolves to a zero-byte payload for a # commit/tree/tag is malformed: ``_parse_message`` / # ``parse_tree`` accept the empty input silently, so without # this guard a too-short delta could materialise an # otherwise-valid SHA pointing at an empty commit object # (which ``git fsck`` rejects). Only blobs may legitimately # be empty, and an empty blob would never be stored as a # delta in practice. # Blob.type_num == 3 (avoid the import cycle). if obj_type_num != 3 and chunks_length(unpacked.obj_chunks) == 0: raise ApplyDeltaError( f"delta resolved to empty payload for type {obj_type_num}" ) return unpacked def _follow_chain( self, offset: int, obj_type_num: int, base_chunks: bytes | list[bytes] | None, ) -> Iterator[T]: # Unlike PackData.get_object_at, there is no need to cache offsets as # this approach by design inflates each object exactly once. todo = [(offset, obj_type_num, base_chunks)] while todo: (offset, obj_type_num, base_chunks) = todo.pop() unpacked = self._resolve_object(offset, obj_type_num, base_chunks) yield self._result(unpacked) assert unpacked.offset is not None unblocked = chain( self._pending_ofs.pop(unpacked.offset, []), self._pending_ref.pop(unpacked.sha(), []), ) todo.extend( (new_offset, unpacked.obj_type_num, unpacked.obj_chunks) # type: ignore for new_offset in unblocked ) def __iter__(self) -> Iterator[T]: """Iterate over objects in the pack.""" return self._walk_all_chains() def ext_refs(self) -> list[RawObjectID]: """Return external references.""" return self._ext_refs class UnpackedObjectIterator(DeltaChainIterator[UnpackedObject]): """Delta chain iterator that yield unpacked objects.""" def _result(self, unpacked: UnpackedObject) -> UnpackedObject: """Return the unpacked object. Args: unpacked: The unpacked object Returns: The unpacked object unchanged """ return unpacked class PackIndexer(DeltaChainIterator[PackIndexEntry]): """Delta chain iterator that yields index entries.""" _compute_crc32 = True def _result(self, unpacked: UnpackedObject) -> PackIndexEntry: """Convert unpacked object to pack index entry. Args: unpacked: The unpacked object Returns: Tuple of (sha, offset, crc32) for index entry """ assert unpacked.offset is not None return unpacked.sha(), unpacked.offset, unpacked.crc32 class PackInflater(DeltaChainIterator[ShaFile]): """Delta chain iterator that yields ShaFile objects.""" def _result(self, unpacked: UnpackedObject) -> ShaFile: """Convert unpacked object to ShaFile. Args: unpacked: The unpacked object Returns: ShaFile object from the unpacked data """ assert unpacked.obj_type_num is not None and unpacked.obj_chunks is not None return ShaFile.from_raw_chunks( unpacked.obj_type_num, unpacked.obj_chunks, object_format=self._object_format, ) class SHA1Reader(BinaryIO): """Wrapper for file-like object that remembers the SHA1 of its data.""" def __init__(self, f: IO[bytes]) -> None: """Initialize SHA1Reader. Args: f: File-like object to wrap """ self.f = f self.sha1 = sha1(b"") def read(self, size: int = -1) -> bytes: """Read bytes and update SHA1. Args: size: Number of bytes to read, -1 for all Returns: Bytes read from file """ data = self.f.read(size) self.sha1.update(data) return data def check_sha(self, allow_empty: bool = False) -> None: """Check if the SHA1 matches the expected value. Args: allow_empty: Allow empty SHA1 hash Raises: ChecksumMismatch: If SHA1 doesn't match """ stored = self.f.read(20) # If git option index.skipHash is set the index will be empty if stored != self.sha1.digest() and ( not allow_empty or ( len(stored) == 20 and sha_to_hex(RawObjectID(stored)) != b"0000000000000000000000000000000000000000" ) ): raise ChecksumMismatch( self.sha1.hexdigest(), sha_to_hex(RawObjectID(stored)) if stored else b"", ) def close(self) -> None: """Close the underlying file.""" return self.f.close() def tell(self) -> int: """Return current file position.""" return self.f.tell() # BinaryIO abstract methods def readable(self) -> bool: """Check if file is readable.""" return True def writable(self) -> bool: """Check if file is writable.""" return False def seekable(self) -> bool: """Check if file is seekable.""" return getattr(self.f, "seekable", lambda: False)() def seek(self, offset: int, whence: int = 0) -> int: """Seek to position in file. Args: offset: Position offset whence: Reference point (0=start, 1=current, 2=end) Returns: New file position """ return self.f.seek(offset, whence) def flush(self) -> None: """Flush the file buffer.""" if hasattr(self.f, "flush"): self.f.flush() def readline(self, size: int = -1) -> bytes: """Read a line from the file. Args: size: Maximum bytes to read Returns: Line read from file """ return self.f.readline(size) def readlines(self, hint: int = -1) -> list[bytes]: """Read all lines from the file. Args: hint: Approximate number of bytes to read Returns: List of lines """ return self.f.readlines(hint) def writelines(self, lines: Iterable[bytes], /) -> None: # type: ignore[override] """Write multiple lines to the file (not supported).""" raise UnsupportedOperation("writelines") def write(self, data: bytes, /) -> int: # type: ignore[override] """Write data to the file (not supported).""" raise UnsupportedOperation("write") def __enter__(self) -> Self: """Enter context manager.""" return self def __exit__( self, type: type | None, value: BaseException | None, traceback: TracebackType | None, ) -> None: """Exit context manager and close file.""" self.close() def __iter__(self) -> "SHA1Reader": """Return iterator for reading file lines.""" return self def __next__(self) -> bytes: """Get next line from file. Returns: Next line Raises: StopIteration: When no more lines """ line = self.readline() if not line: raise StopIteration return line def fileno(self) -> int: """Return file descriptor number.""" return self.f.fileno() def isatty(self) -> bool: """Check if file is a terminal.""" return getattr(self.f, "isatty", lambda: False)() def truncate(self, size: int | None = None) -> int: """Not supported for read-only file. Raises: UnsupportedOperation: Always raised """ raise UnsupportedOperation("truncate") class SHA1Writer(BinaryIO): """Wrapper for file-like object that remembers the SHA1 of its data.""" def __init__(self, f: BinaryIO | IO[bytes]) -> None: """Initialize SHA1Writer. Args: f: File-like object to wrap """ self.f = f self.length = 0 self.sha1 = sha1(b"") self.digest: bytes | None = None def write(self, data: bytes | bytearray | memoryview, /) -> int: # type: ignore[override] """Write data and update SHA1. Args: data: Data to write Returns: Number of bytes written """ self.sha1.update(data) written = self.f.write(data) self.length += written return written def write_sha(self) -> bytes: """Write the SHA1 digest to the file. Returns: The SHA1 digest bytes """ sha = self.sha1.digest() assert len(sha) == 20 self.f.write(sha) self.length += len(sha) return sha def close(self) -> None: """Close the pack file and finalize the SHA.""" self.digest = self.write_sha() self.f.close() def offset(self) -> int: """Get the total number of bytes written. Returns: Total bytes written """ return self.length def tell(self) -> int: """Return current file position.""" return self.f.tell() # BinaryIO abstract methods def readable(self) -> bool: """Check if file is readable.""" return False def writable(self) -> bool: """Check if file is writable.""" return True def seekable(self) -> bool: """Check if file is seekable.""" return getattr(self.f, "seekable", lambda: False)() def seek(self, offset: int, whence: int = 0) -> int: """Seek to position in file. Args: offset: Position offset whence: Reference point (0=start, 1=current, 2=end) Returns: New file position """ return self.f.seek(offset, whence) def flush(self) -> None: """Flush the file buffer.""" if hasattr(self.f, "flush"): self.f.flush() def readline(self, size: int = -1) -> bytes: """Not supported for write-only file. Raises: UnsupportedOperation: Always raised """ raise UnsupportedOperation("readline") def readlines(self, hint: int = -1) -> list[bytes]: """Not supported for write-only file. Raises: UnsupportedOperation: Always raised """ raise UnsupportedOperation("readlines") def writelines(self, lines: Iterable[bytes], /) -> None: # type: ignore[override] """Write multiple lines to the file. Args: lines: Iterable of lines to write """ for line in lines: self.write(line) def read(self, size: int = -1) -> bytes: """Not supported for write-only file. Raises: UnsupportedOperation: Always raised """ raise UnsupportedOperation("read") def __enter__(self) -> Self: """Enter context manager.""" return self def __exit__( self, type: type | None, value: BaseException | None, traceback: TracebackType | None, ) -> None: """Exit context manager and close file.""" self.f.close() def __iter__(self) -> "SHA1Writer": """Return iterator.""" return self def __next__(self) -> bytes: """Not supported for write-only file. Raises: UnsupportedOperation: Always raised """ raise UnsupportedOperation("__next__") def fileno(self) -> int: """Return file descriptor number.""" return self.f.fileno() def isatty(self) -> bool: """Check if file is a terminal.""" return getattr(self.f, "isatty", lambda: False)() def truncate(self, size: int | None = None) -> int: """Not supported for write-only file. Raises: UnsupportedOperation: Always raised """ raise UnsupportedOperation("truncate") class HashWriter(BinaryIO): """Wrapper for file-like object that computes hash of its data. This is a generic version that works with any hash algorithm. """ def __init__( self, f: BinaryIO | IO[bytes], hash_func: Callable[[], "HashObject"] ) -> None: """Initialize HashWriter. Args: f: File-like object to wrap hash_func: Hash function (e.g., sha1, sha256) """ self.f = f self.length = 0 self.hash_obj = hash_func() self.digest: bytes | None = None def write(self, data: bytes | bytearray | memoryview, /) -> int: # type: ignore[override] """Write data and update hash. Args: data: Data to write Returns: Number of bytes written """ self.hash_obj.update(data) written = self.f.write(data) self.length += written return written def write_hash(self) -> bytes: """Write the hash digest to the file. Returns: The hash digest bytes """ digest = self.hash_obj.digest() self.f.write(digest) self.length += len(digest) return digest def close(self) -> None: """Close the pack file and finalize the hash.""" self.digest = self.write_hash() self.f.close() def offset(self) -> int: """Get the total number of bytes written. Returns: Total bytes written """ return self.length def tell(self) -> int: """Return current file position.""" return self.f.tell() # BinaryIO abstract methods def readable(self) -> bool: """Check if file is readable.""" return False def writable(self) -> bool: """Check if file is writable.""" return True def seekable(self) -> bool: """Check if file is seekable.""" return getattr(self.f, "seekable", lambda: False)() def seek(self, offset: int, whence: int = 0) -> int: """Seek to position in file. Args: offset: Position offset whence: Reference point (0=start, 1=current, 2=end) Returns: New file position """ return self.f.seek(offset, whence) def flush(self) -> None: """Flush the file buffer.""" if hasattr(self.f, "flush"): self.f.flush() def readline(self, size: int = -1) -> bytes: """Not supported for write-only file. Raises: UnsupportedOperation: Always raised """ raise UnsupportedOperation("readline") def readlines(self, hint: int = -1) -> list[bytes]: """Not supported for write-only file. Raises: UnsupportedOperation: Always raised """ raise UnsupportedOperation("readlines") def writelines(self, lines: Iterable[bytes], /) -> None: # type: ignore[override] """Write multiple lines to the file. Args: lines: Iterable of lines to write """ for line in lines: self.write(line) def read(self, size: int = -1) -> bytes: """Not supported for write-only file. Raises: UnsupportedOperation: Always raised """ raise UnsupportedOperation("read") def __enter__(self) -> Self: """Enter context manager.""" return self def __exit__( self, type: type | None, value: BaseException | None, traceback: TracebackType | None, ) -> None: """Exit context manager and close file.""" self.close() def __iter__(self) -> "HashWriter": """Return iterator.""" return self def __next__(self) -> bytes: """Not supported for write-only file. Raises: UnsupportedOperation: Always raised """ raise UnsupportedOperation("__next__") def fileno(self) -> int: """Return file descriptor number.""" return self.f.fileno() def isatty(self) -> bool: """Check if file is a terminal.""" return getattr(self.f, "isatty", lambda: False)() def truncate(self, size: int | None = None) -> int: """Not supported for write-only file. Raises: UnsupportedOperation: Always raised """ raise UnsupportedOperation("truncate") def pack_object_header( type_num: int, delta_base: bytes | int | None, size: int, object_format: "ObjectFormat", ) -> bytearray: """Create a pack object header for the given object info. Args: type_num: Numeric type of the object. delta_base: Delta base offset or ref, or None for whole objects. size: Uncompressed object size. object_format: Object format (hash algorithm) to use. Returns: A header for a packed object. """ header = [] c = (type_num << 4) | (size & 15) size >>= 4 while size: header.append(c | 0x80) c = size & 0x7F size >>= 7 header.append(c) if type_num == OFS_DELTA: assert isinstance(delta_base, int) ret = [delta_base & 0x7F] delta_base >>= 7 while delta_base: delta_base -= 1 ret.insert(0, 0x80 | (delta_base & 0x7F)) delta_base >>= 7 header.extend(ret) elif type_num == REF_DELTA: assert isinstance(delta_base, bytes) assert len(delta_base) == object_format.oid_length header += delta_base return bytearray(header) def pack_object_chunks( type: int, object: list[bytes] | tuple[bytes | int, list[bytes]], object_format: "ObjectFormat", *, compression_level: int = -1, ) -> Iterator[bytes]: """Generate chunks for a pack object. Args: type: Numeric type of the object object: Object to write object_format: Object format (hash algorithm) to use compression_level: the zlib compression level Returns: Chunks """ if type in DELTA_TYPES: if isinstance(object, tuple): delta_base, object = object else: raise TypeError("Delta types require a tuple of (delta_base, object)") else: delta_base = None # Convert object to list of bytes chunks if isinstance(object, bytes): chunks = [object] elif isinstance(object, list): chunks = object elif isinstance(object, ShaFile): chunks = object.as_raw_chunks() else: # Shouldn't reach here with proper typing raise TypeError(f"Unexpected object type: {object.__class__.__name__}") yield bytes( pack_object_header( type, delta_base, sum(map(len, chunks)), object_format=object_format ) ) compressor = zlib.compressobj(level=compression_level) for data in chunks: yield compressor.compress(data) yield compressor.flush() def write_pack_object( write: Callable[[bytes], int], type: int, object: list[bytes] | tuple[bytes | int, list[bytes]], object_format: "ObjectFormat", *, sha: "HashObject | None" = None, compression_level: int = -1, ) -> int: """Write pack object to a file. Args: write: Write function to use type: Numeric type of the object object: Object to write object_format: Object format (hash algorithm) to use sha: Optional SHA-1 hasher to update compression_level: the zlib compression level Returns: CRC32 checksum of the written object """ crc32 = 0 for chunk in pack_object_chunks( type, object, compression_level=compression_level, object_format=object_format ): write(chunk) if sha is not None: sha.update(chunk) crc32 = binascii.crc32(chunk, crc32) return crc32 & 0xFFFFFFFF def write_pack( filename: str, objects: Sequence[ShaFile] | Sequence[tuple[ShaFile, bytes | None]], object_format: "ObjectFormat", *, deltify: bool | None = None, delta_window_size: int | None = None, compression_level: int = -1, ) -> tuple[bytes, bytes]: """Write a new pack data file. Args: filename: Path to the new pack file (without .pack extension) objects: Objects to write to the pack object_format: Object format delta_window_size: Delta window size deltify: Whether to deltify pack objects compression_level: the zlib compression level Returns: Tuple with checksum of pack file and index file """ with GitFile(filename + ".pack", "wb") as f: entries, data_sum = write_pack_objects( f, objects, delta_window_size=delta_window_size, deltify=deltify, compression_level=compression_level, object_format=object_format, ) entries_list = sorted([(k, v[0], v[1]) for (k, v) in entries.items()]) with GitFile(filename + ".idx", "wb") as f: idx_sha = write_pack_index(f, entries_list, data_sum) return data_sum, idx_sha def pack_header_chunks(num_objects: int) -> Iterator[bytes]: """Yield chunks for a pack header.""" yield b"PACK" # Pack header yield struct.pack(b">L", 2) # Pack version yield struct.pack(b">L", num_objects) # Number of objects in pack def write_pack_header( write: Callable[[bytes], int] | IO[bytes], num_objects: int ) -> None: """Write a pack header for the given number of objects.""" if not callable(write): write_fn: Callable[[bytes], int] = write.write warnings.warn( "write_pack_header() now takes a write rather than file argument", DeprecationWarning, stacklevel=2, ) else: write_fn = write for chunk in pack_header_chunks(num_objects): write_fn(chunk) def find_reusable_deltas( container: PackedObjectContainer, object_ids: Set[ObjectID], *, other_haves: Set[ObjectID] | None = None, progress: Callable[..., None] | None = None, ) -> Iterator[UnpackedObject]: """Find deltas in a pack that can be reused. Args: container: Pack container to search for deltas object_ids: Set of object IDs to find deltas for other_haves: Set of other object IDs we have progress: Optional progress reporting callback Returns: Iterator of UnpackedObject entries that can be reused """ if other_haves is None: other_haves = set() reused = 0 for i, unpacked in enumerate( container.iter_unpacked_subset( object_ids, allow_missing=True, convert_ofs_delta=True ) ): if progress is not None and i % 1000 == 0: progress(f"checking for reusable deltas: {i}/{len(object_ids)}\r".encode()) if unpacked.pack_type_num == REF_DELTA: hexsha = sha_to_hex(unpacked.delta_base) # type: ignore if hexsha in object_ids or hexsha in other_haves: yield unpacked reused += 1 if progress is not None: progress((f"found {reused} deltas to reuse\n").encode()) def deltify_pack_objects( objects: Iterator[ShaFile] | Iterator[tuple[ShaFile, bytes | None]], *, window_size: int | None = None, progress: Callable[..., None] | None = None, ) -> Iterator[UnpackedObject]: """Generate deltas for pack objects. Args: objects: An iterable of (object, path) tuples to deltify. window_size: Window size; None for default progress: Optional progress reporting callback Returns: Iterator over type_num, object id, delta_base, content delta_base is None for full text entries """ def objects_with_hints() -> Iterator[tuple[ShaFile, tuple[int, bytes | None]]]: for e in objects: if isinstance(e, ShaFile): yield (e, (e.type_num, None)) else: yield (e[0], (e[0].type_num, e[1])) sorted_objs = sort_objects_for_delta(objects_with_hints()) yield from deltas_from_sorted_objects( sorted_objs, window_size=window_size, progress=progress, ) def sort_objects_for_delta( objects: Iterator[ShaFile] | Iterator[tuple[ShaFile, PackHint | None]], ) -> Iterator[tuple[ShaFile, bytes | None]]: """Sort objects for optimal delta compression. Args: objects: Iterator of objects or (object, hint) tuples Returns: Iterator of sorted (ShaFile, path) tuples """ magic = [] for entry in objects: if isinstance(entry, tuple): obj, hint = entry if hint is None: type_num = None path = None else: (type_num, path) = hint else: obj = entry type_num = None path = None magic.append((type_num, path, -obj.raw_length(), obj)) # Build a list of objects ordered by the magic Linus heuristic # This helps us find good objects to diff against us magic.sort() return ((x[3], x[1]) for x in magic) def deltas_from_sorted_objects( objects: Iterator[tuple[ShaFile, bytes | None]], window_size: int | None = None, progress: Callable[..., None] | None = None, ) -> Iterator[UnpackedObject]: """Create deltas from sorted objects. Args: objects: Iterator of sorted objects to deltify window_size: Delta window size; None for default progress: Optional progress reporting callback Returns: Iterator of UnpackedObject entries """ # TODO(jelmer): Use threads if window_size is None: window_size = DEFAULT_PACK_DELTA_WINDOW_SIZE possible_bases: deque[tuple[bytes, int, bytes]] = deque() for i, (o, path) in enumerate(objects): if progress is not None and i % 1000 == 0: progress((f"generating deltas: {i}\r").encode()) raw = o.as_raw_chunks() raw_bytes = b"".join(raw) # Join once for efficiency winner = raw winner_len = sum(map(len, winner)) winner_base = None for base_id, base_type_num, base_bytes in possible_bases: if base_type_num != o.type_num: continue delta_len = 0 delta = [] for chunk in create_delta(base_bytes, raw_bytes): delta_len += len(chunk) if delta_len >= winner_len: break delta.append(chunk) else: winner_base = base_id winner = delta winner_len = sum(map(len, winner)) yield UnpackedObject( o.type_num, sha=o.sha().digest(), delta_base=winner_base, decomp_len=winner_len, decomp_chunks=winner, ) possible_bases.appendleft((o.sha().digest(), o.type_num, raw_bytes)) while len(possible_bases) > window_size: possible_bases.pop() def pack_objects_to_data( objects: Sequence[ShaFile] | Sequence[tuple[ShaFile, bytes | None]] | Sequence[tuple[ShaFile, PackHint | None]], *, deltify: bool | None = None, delta_window_size: int | None = None, ofs_delta: bool = True, progress: Callable[..., None] | None = None, ) -> tuple[int, Iterator[UnpackedObject]]: """Create pack data from objects. Args: objects: Pack objects deltify: Whether to deltify pack objects delta_window_size: Delta window size ofs_delta: Whether to use offset deltas progress: Optional progress reporting callback Returns: Tuples with (type_num, hexdigest, delta base, object chunks) """ count = len(objects) if deltify is None: # PERFORMANCE/TODO(jelmer): This should be enabled but the python # implementation is *much* too slow at the moment. # Maybe consider enabling it just if the rust extension is available? deltify = False if deltify: return ( count, deltify_pack_objects( iter(objects), # type: ignore window_size=delta_window_size, progress=progress, ), ) else: def iter_without_path() -> Iterator[UnpackedObject]: for o in objects: if isinstance(o, tuple): yield full_unpacked_object(o[0]) else: yield full_unpacked_object(o) return (count, iter_without_path()) def generate_unpacked_objects( container: PackedObjectContainer, object_ids: Sequence[tuple[ObjectID, PackHint | None]], delta_window_size: int | None = None, deltify: bool | None = None, reuse_deltas: bool = True, ofs_delta: bool = True, other_haves: set[ObjectID] | None = None, progress: Callable[..., None] | None = None, ) -> Iterator[UnpackedObject]: """Create pack data from objects. Returns: Tuples with (type_num, hexdigest, delta base, object chunks) """ todo = dict(object_ids) if reuse_deltas: for unpack in find_reusable_deltas( container, set(todo), other_haves=other_haves, progress=progress ): del todo[sha_to_hex(RawObjectID(unpack.sha()))] yield unpack if deltify is None: # PERFORMANCE/TODO(jelmer): This should be enabled but is *much* too # slow at the moment. deltify = False if deltify: objects_to_delta = container.iterobjects_subset( todo.keys(), allow_missing=False ) sorted_objs = sort_objects_for_delta((o, todo[o.id]) for o in objects_to_delta) yield from deltas_from_sorted_objects( sorted_objs, window_size=delta_window_size, progress=progress, ) else: for oid in todo: yield full_unpacked_object(container[oid]) def full_unpacked_object(o: ShaFile) -> UnpackedObject: """Create an UnpackedObject from a ShaFile. Args: o: ShaFile object to convert Returns: UnpackedObject with full object data """ return UnpackedObject( o.type_num, delta_base=None, crc32=None, decomp_chunks=o.as_raw_chunks(), sha=o.sha().digest(), ) def write_pack_from_container( write: Callable[[bytes], None] | Callable[[bytes | bytearray | memoryview], int] | IO[bytes], container: PackedObjectContainer, object_ids: Sequence[tuple[ObjectID, PackHint | None]], object_format: "ObjectFormat", *, delta_window_size: int | None = None, deltify: bool | None = None, reuse_deltas: bool = True, compression_level: int = -1, other_haves: set[ObjectID] | None = None, ) -> tuple[dict[bytes, tuple[int, int]], bytes]: """Write a new pack data file. Args: write: write function to use container: PackedObjectContainer object_ids: Sequence of (object_id, hint) tuples to write object_format: Object format (hash algorithm) to use delta_window_size: Sliding window size for searching for deltas; Set to None for default window size. deltify: Whether to deltify objects reuse_deltas: Whether to reuse existing deltas compression_level: the zlib compression level to use other_haves: Set of additional object IDs the receiver has Returns: Dict mapping id -> (offset, crc32 checksum), pack checksum """ pack_contents_count = len(object_ids) pack_contents = generate_unpacked_objects( container, object_ids, delta_window_size=delta_window_size, deltify=deltify, reuse_deltas=reuse_deltas, other_haves=other_haves, ) return write_pack_data( write, pack_contents, num_records=pack_contents_count, compression_level=compression_level, object_format=object_format, ) def write_pack_objects( write: Callable[[bytes], None] | IO[bytes], objects: Sequence[ShaFile] | Sequence[tuple[ShaFile, bytes | None]], object_format: "ObjectFormat", *, delta_window_size: int | None = None, deltify: bool | None = None, compression_level: int = -1, ) -> tuple[dict[bytes, tuple[int, int]], bytes]: """Write a new pack data file. Args: write: write function to use objects: Sequence of (object, path) tuples to write object_format: Object format (hash algorithm) to use delta_window_size: Sliding window size for searching for deltas; Set to None for default window size. deltify: Whether to deltify objects compression_level: the zlib compression level to use Returns: Dict mapping id -> (offset, crc32 checksum), pack checksum """ pack_contents_count, pack_contents = pack_objects_to_data(objects, deltify=deltify) return write_pack_data( write, pack_contents, num_records=pack_contents_count, compression_level=compression_level, object_format=object_format, ) class PackChunkGenerator: """Generator for pack data chunks.""" def __init__( self, object_format: "ObjectFormat", num_records: int | None = None, records: Iterator[UnpackedObject] | None = None, progress: Callable[..., None] | None = None, compression_level: int = -1, reuse_compressed: bool = True, ) -> None: """Initialize PackChunkGenerator. Args: num_records: Expected number of records records: Iterator of pack records progress: Optional progress callback compression_level: Compression level (-1 for default) reuse_compressed: Whether to reuse compressed chunks object_format: Object format (hash algorithm) to use """ self.object_format = object_format self.cs = object_format.new_hash() self.entries: dict[bytes, tuple[int, int]] = {} if records is None: records = iter([]) # Empty iterator if None self._it = self._pack_data_chunks( records=records, num_records=num_records, progress=progress, compression_level=compression_level, reuse_compressed=reuse_compressed, ) def sha1digest(self) -> bytes: """Return the SHA1 digest of the pack data.""" return self.cs.digest() def __iter__(self) -> Iterator[bytes]: """Iterate over pack data chunks.""" return self._it def _pack_data_chunks( self, records: Iterator[UnpackedObject], *, num_records: int | None = None, progress: Callable[..., None] | None = None, compression_level: int = -1, reuse_compressed: bool = True, ) -> Iterator[bytes]: """Iterate pack data file chunks. Args: records: Iterator over UnpackedObject num_records: Number of records (defaults to len(records) if not specified) progress: Function to report progress to compression_level: the zlib compression level reuse_compressed: Whether to reuse compressed chunks Returns: Dict mapping id -> (offset, crc32 checksum), pack checksum """ # Write the pack if num_records is None: num_records = len(records) # type: ignore offset = 0 for chunk in pack_header_chunks(num_records): yield chunk self.cs.update(chunk) offset += len(chunk) actual_num_records = 0 for i, unpacked in enumerate(records): type_num = unpacked.pack_type_num if progress is not None and i % 1000 == 0: progress((f"writing pack data: {i}/{num_records}\r").encode("ascii")) raw: list[bytes] | tuple[int, list[bytes]] | tuple[bytes, list[bytes]] if unpacked.delta_base is not None: assert isinstance(unpacked.delta_base, bytes), ( f"Expected bytes, got {type(unpacked.delta_base)}" ) try: base_offset, _base_crc32 = self.entries[unpacked.delta_base] except KeyError: type_num = REF_DELTA assert isinstance(unpacked.delta_base, bytes) raw = (unpacked.delta_base, unpacked.decomp_chunks) else: type_num = OFS_DELTA raw = (offset - base_offset, unpacked.decomp_chunks) else: raw = unpacked.decomp_chunks chunks: list[bytes] | Iterator[bytes] if unpacked.comp_chunks is not None and reuse_compressed: chunks = unpacked.comp_chunks else: chunks = pack_object_chunks( type_num, raw, compression_level=compression_level, object_format=self.object_format, ) crc32 = 0 object_size = 0 for chunk in chunks: yield chunk crc32 = binascii.crc32(chunk, crc32) self.cs.update(chunk) object_size += len(chunk) actual_num_records += 1 self.entries[unpacked.sha()] = (offset, crc32) offset += object_size if actual_num_records != num_records: raise AssertionError( f"actual records written differs: {actual_num_records} != {num_records}" ) yield self.cs.digest() def write_pack_data( write: Callable[[bytes], None] | Callable[[bytes | bytearray | memoryview], int] | IO[bytes], records: Iterator[UnpackedObject], object_format: "ObjectFormat", *, num_records: int | None = None, progress: Callable[..., None] | None = None, compression_level: int = -1, ) -> tuple[dict[bytes, tuple[int, int]], bytes]: """Write a new pack data file. Args: write: Write function to use num_records: Number of records (defaults to len(records) if None) records: Iterator over type_num, object_id, delta_base, raw object_format: Object format (hash algorithm) to use progress: Function to report progress to compression_level: the zlib compression level Returns: Dict mapping id -> (offset, crc32 checksum), pack checksum """ chunk_generator = PackChunkGenerator( num_records=num_records, records=records, progress=progress, compression_level=compression_level, object_format=object_format, ) for chunk in chunk_generator: if callable(write): write(chunk) else: write.write(chunk) return chunk_generator.entries, chunk_generator.sha1digest() def write_pack_index_v1( f: IO[bytes], entries: Iterable[tuple[bytes, int, int | None]], pack_checksum: bytes, ) -> bytes: """Write a new pack index file. Args: f: A file-like object to write to entries: List of tuples with object name (sha), offset_in_pack, and crc32_checksum. pack_checksum: Checksum of the pack file. Returns: The SHA of the written index file """ f = SHA1Writer(f) fan_out_table: dict[int, int] = defaultdict(lambda: 0) for name, _offset, _entry_checksum in entries: fan_out_table[ord(name[:1])] += 1 # Fan-out table for i in range(0x100): f.write(struct.pack(">L", fan_out_table[i])) fan_out_table[i + 1] += fan_out_table[i] for name, offset, _entry_checksum in entries: if len(name) != 20: raise TypeError("pack index v1 only supports SHA-1 names") if not (offset <= 0xFFFFFFFF): raise TypeError("pack format 1 only supports offsets < 2Gb") f.write(struct.pack(">L20s", offset, name)) assert len(pack_checksum) == 20 f.write(pack_checksum) return f.write_sha() def _delta_encode_size(size: int) -> bytes: ret = bytearray() c = size & 0x7F size >>= 7 while size: ret.append(c | 0x80) c = size & 0x7F size >>= 7 ret.append(c) return bytes(ret) # The length of delta compression copy operations in version 2 packs is limited # to 64K. To copy more, we use several copy operations. Version 3 packs allow # 24-bit lengths in copy operations, but we always make version 2 packs. _MAX_COPY_LEN = 0xFFFF def _encode_copy_operation(start: int, length: int) -> bytes: scratch = bytearray([0x80]) for i in range(4): if start & 0xFF << i * 8: scratch.append((start >> i * 8) & 0xFF) scratch[0] |= 1 << i for i in range(2): if length & 0xFF << i * 8: scratch.append((length >> i * 8) & 0xFF) scratch[0] |= 1 << (4 + i) return bytes(scratch) def _create_delta_py( base_buf: bytes | list[bytes], target_buf: bytes | list[bytes] ) -> Iterator[bytes]: """Use python difflib to work out how to transform base_buf to target_buf. Args: base_buf: Base buffer target_buf: Target buffer """ if isinstance(base_buf, list): base_buf = b"".join(base_buf) if isinstance(target_buf, list): target_buf = b"".join(target_buf) # write delta header yield _delta_encode_size(len(base_buf)) yield _delta_encode_size(len(target_buf)) # write out delta opcodes seq = SequenceMatcher(isjunk=None, a=base_buf, b=target_buf) for opcode, i1, i2, j1, j2 in seq.get_opcodes(): # Git patch opcodes don't care about deletes! # if opcode == 'replace' or opcode == 'delete': # pass if opcode == "equal": # If they are equal, unpacker will use data from base_buf # Write out an opcode that says what range to use copy_start = i1 copy_len = i2 - i1 while copy_len > 0: to_copy = min(copy_len, _MAX_COPY_LEN) yield _encode_copy_operation(copy_start, to_copy) copy_start += to_copy copy_len -= to_copy if opcode == "replace" or opcode == "insert": # If we are replacing a range or adding one, then we just # output it to the stream (prefixed by its size) s = j2 - j1 o = j1 while s > 127: yield bytes([127]) yield bytes(memoryview(target_buf)[o : o + 127]) s -= 127 o += 127 yield bytes([s]) yield bytes(memoryview(target_buf)[o : o + s]) # Default to pure Python implementation create_delta = _create_delta_py def apply_delta( src_buf: bytes | list[bytes], delta: bytes | list[bytes] ) -> list[bytes]: """Based on the similar function in git's patch-delta.c. Args: src_buf: Source buffer delta: Delta instructions """ if not isinstance(src_buf, bytes): src_buf = b"".join(src_buf) if not isinstance(delta, bytes): delta = b"".join(delta) out = [] index = 0 delta_length = len(delta) def get_delta_header_size(delta: bytes, index: int) -> tuple[int, int]: size = 0 i = 0 while True: # Bound-check explicitly: ``delta[index:index+1]`` silently # returns b"" past the end, which would crash with TypeError # in ``ord`` and leave the caller unable to distinguish a # truncated delta from a programming bug. if index >= delta_length: raise ApplyDeltaError("delta truncated in size header") cmd = ord(delta[index : index + 1]) index += 1 size |= (cmd & ~0x80) << i i += 7 if not cmd & 0x80: break return size, index def read_byte(delta: bytes) -> int: nonlocal index # Bound-check explicitly: ``delta[index:index+1]`` silently returns # b"" past the end, which would crash with TypeError in ``ord`` and # leave the caller unable to distinguish a truncated delta from a # programming bug. if index >= delta_length: raise ApplyDeltaError("delta truncated in copy op") index += 1 return ord(delta[index - 1 : index]) src_size, index = get_delta_header_size(delta, index) dest_size, index = get_delta_header_size(delta, index) if src_size != len(src_buf): raise ApplyDeltaError( f"Unexpected source buffer size: {src_size} vs {len(src_buf)}" ) while index < delta_length: cmd = ord(delta[index : index + 1]) index += 1 if cmd & 0x80: cp_off = 0 for i in range(4): if cmd & (1 << i): x = read_byte(delta) cp_off |= x << (i * 8) cp_size = 0 # Version 3 packs can contain copy sizes larger than 64K. for i in range(3): if cmd & (1 << (4 + i)): x = read_byte(delta) cp_size |= x << (i * 8) if cp_size == 0: cp_size = 0x10000 if ( cp_off + cp_size < cp_size or cp_off + cp_size > src_size or cp_size > dest_size ): break out.append(src_buf[cp_off : cp_off + cp_size]) elif cmd != 0: if index + cmd > delta_length: raise ApplyDeltaError("delta truncated in insert op") out.append(delta[index : index + cmd]) index += cmd else: raise ApplyDeltaError("Invalid opcode 0") if index != delta_length: raise ApplyDeltaError(f"delta not empty: {delta[index:]!r}") if dest_size != chunks_length(out): raise ApplyDeltaError("dest size incorrect") return out def write_pack_index_v2( f: IO[bytes], entries: Iterable[tuple[bytes, int, int | None]], pack_checksum: bytes, ) -> bytes: """Write a new pack index file. Args: f: File-like object to write to entries: List of tuples with object name (sha), offset_in_pack, and crc32_checksum. pack_checksum: Checksum of the pack file. Returns: The checksum of the index file written """ # Determine hash algorithm from pack_checksum length if len(pack_checksum) == 20: hash_func = sha1 elif len(pack_checksum) == 32: hash_func = sha256 else: raise ValueError(f"Unsupported pack checksum length: {len(pack_checksum)}") f_writer = HashWriter(f, hash_func) f_writer.write(b"\377tOc") # Magic! f_writer.write(struct.pack(">L", 2)) # Convert to list to allow multiple iterations entries_list = list(entries) fan_out_table: dict[int, int] = defaultdict(lambda: 0) for name, offset, entry_checksum in entries_list: fan_out_table[ord(name[:1])] += 1 if entries_list: hash_size = len(entries_list[0][0]) else: hash_size = len(pack_checksum) # Use pack_checksum length as hash size # Fan-out table largetable: list[int] = [] for i in range(0x100): f_writer.write(struct.pack(b">L", fan_out_table[i])) fan_out_table[i + 1] += fan_out_table[i] for name, offset, entry_checksum in entries_list: if len(name) != hash_size: raise TypeError( f"Object name has wrong length: expected {hash_size}, got {len(name)}" ) f_writer.write(name) for name, offset, entry_checksum in entries_list: f_writer.write(struct.pack(b">L", entry_checksum)) for name, offset, entry_checksum in entries_list: if offset < 2**31: f_writer.write(struct.pack(b">L", offset)) else: f_writer.write(struct.pack(b">L", 2**31 + len(largetable))) largetable.append(offset) for offset in largetable: f_writer.write(struct.pack(b">Q", offset)) f_writer.write(pack_checksum) return f_writer.write_hash() def write_pack_index_v3( f: IO[bytes], entries: Iterable[tuple[bytes, int, int | None]], pack_checksum: bytes, hash_format: int = 1, ) -> bytes: """Write a new pack index file in v3 format. Args: f: File-like object to write to entries: List of tuples with object name (sha), offset_in_pack, and crc32_checksum. pack_checksum: Checksum of the pack file. hash_format: Hash algorithm identifier (1 = SHA-1, 2 = SHA-256) Returns: The SHA of the index file written """ if hash_format == 1: hash_size = 20 # SHA-1 writer_cls = SHA1Writer elif hash_format == 2: hash_size = 32 # SHA-256 # TODO: Add SHA256Writer when SHA-256 support is implemented raise NotImplementedError("SHA-256 support not yet implemented") else: raise ValueError(f"Unknown hash algorithm {hash_format}") # Convert entries to list to allow multiple iterations entries_list = list(entries) # Calculate shortest unambiguous prefix length for object names # For now, use full hash size (this could be optimized) shortened_oid_len = hash_size f = writer_cls(f) f.write(b"\377tOc") # Magic! f.write(struct.pack(">L", 3)) # Version 3 f.write(struct.pack(">L", hash_format)) # Hash algorithm f.write(struct.pack(">L", shortened_oid_len)) # Shortened OID length fan_out_table: dict[int, int] = defaultdict(lambda: 0) for name, offset, entry_checksum in entries_list: if len(name) != hash_size: raise ValueError( f"Object name has wrong length: expected {hash_size}, got {len(name)}" ) fan_out_table[ord(name[:1])] += 1 # Fan-out table largetable: list[int] = [] for i in range(0x100): f.write(struct.pack(b">L", fan_out_table[i])) fan_out_table[i + 1] += fan_out_table[i] # Object names table for name, offset, entry_checksum in entries_list: f.write(name) # CRC32 checksums table for name, offset, entry_checksum in entries_list: f.write(struct.pack(b">L", entry_checksum)) # Offset table for name, offset, entry_checksum in entries_list: if offset < 2**31: f.write(struct.pack(b">L", offset)) else: f.write(struct.pack(b">L", 2**31 + len(largetable))) largetable.append(offset) # Large offset table for offset in largetable: f.write(struct.pack(b">Q", offset)) assert len(pack_checksum) == hash_size, ( f"Pack checksum has wrong length: expected {hash_size}, got {len(pack_checksum)}" ) f.write(pack_checksum) return f.write_sha() def write_pack_index( f: IO[bytes], entries: Iterable[tuple[bytes, int, int | None]], pack_checksum: bytes, progress: Callable[..., None] | None = None, version: int | None = None, ) -> bytes: """Write a pack index file. Args: f: File-like object to write to. entries: List of (checksum, offset, crc32) tuples pack_checksum: Checksum of the pack file. progress: Progress function (not currently used) version: Pack index version to use (1, 2, or 3). If None, defaults to DEFAULT_PACK_INDEX_VERSION. Returns: SHA of the written index file Raises: ValueError: If an unsupported version is specified """ if version is None: version = DEFAULT_PACK_INDEX_VERSION if version == 1: return write_pack_index_v1(f, entries, pack_checksum) elif version == 2: return write_pack_index_v2(f, entries, pack_checksum) elif version == 3: return write_pack_index_v3(f, entries, pack_checksum) else: raise ValueError(f"Unsupported pack index version: {version}") class Pack: """A Git pack object.""" _data_load: Callable[[], PackData] | None _idx_load: Callable[[], PackIndex] | None _data: PackData | None _idx: PackIndex | None _bitmap: "PackBitmap | None" def __init__( self, basename: str, *, object_format: ObjectFormat, resolve_ext_ref: ResolveExtRefFn | None = None, delta_window_size: int | None = None, window_memory: int | None = None, delta_cache_size: int | None = None, depth: int | None = None, threads: int | None = None, big_file_threshold: int | None = None, delta_base_cache_limit: int | None = None, ) -> None: """Initialize a Pack object. Args: basename: Base path for pack files (without .pack/.idx extension) object_format: Hash algorithm used by the repository resolve_ext_ref: Optional function to resolve external references delta_window_size: Size of the delta compression window window_memory: Memory limit for delta compression window delta_cache_size: Size of the delta cache depth: Maximum depth for delta chains threads: Number of threads to use for operations big_file_threshold: Size threshold for big file handling delta_base_cache_limit: Maximum bytes for delta base object cache """ self._basename = basename self.object_format = object_format self._data = None self._idx = None self._bitmap = None self._idx_path = self._basename + ".idx" self._data_path = self._basename + ".pack" self._bitmap_path = self._basename + ".bitmap" self.delta_window_size = delta_window_size self.window_memory = window_memory self.delta_cache_size = delta_cache_size self.depth = depth self.threads = threads self.big_file_threshold = big_file_threshold self.delta_base_cache_limit = delta_base_cache_limit self._idx_load = lambda: load_pack_index(self._idx_path, object_format) self._data_load = lambda: PackData( self._data_path, delta_window_size=delta_window_size, window_memory=window_memory, delta_cache_size=delta_cache_size, depth=depth, threads=threads, big_file_threshold=big_file_threshold, delta_base_cache_limit=delta_base_cache_limit, object_format=object_format, ) self.resolve_ext_ref = resolve_ext_ref @classmethod def from_lazy_objects( cls, data_fn: Callable[[], PackData], idx_fn: Callable[[], PackIndex], ) -> "Pack": """Create a new pack object from callables to load pack data and index objects.""" # Load index to get object format idx = idx_fn() ret = cls("", object_format=idx.object_format) ret._data_load = data_fn ret._idx = idx ret._idx_load = None return ret @classmethod def from_objects(cls, data: PackData, idx: PackIndex) -> "Pack": """Create a new pack object from pack data and index objects.""" ret = cls("", object_format=idx.object_format) ret._data = data ret._data_load = None ret._idx = idx ret._idx_load = None ret.check_length_and_checksum() return ret def name(self) -> bytes: """The SHA over the SHAs of the objects in this pack.""" return self.index.objects_sha1() @property def data(self) -> PackData: """The pack data object being used.""" if self._data is None: assert self._data_load try: self._data = self._data_load() except FileNotFoundError as exc: raise PackFileDisappeared(self) from exc self.check_length_and_checksum() return self._data @property def index(self) -> PackIndex: """The index being used. Note: This may be an in-memory index """ if self._idx is None: assert self._idx_load try: self._idx = self._idx_load() except FileNotFoundError as exc: raise PackFileDisappeared(self) from exc return self._idx @property def bitmap(self) -> "PackBitmap | None": """The bitmap being used, if available. Returns: PackBitmap instance, or None if no bitmap exists or the bitmap was built for a different pack Raises: ValueError: If bitmap file is invalid or corrupt """ if self._bitmap is None: from .bitmap import read_bitmap try: self._bitmap = read_bitmap( self._bitmap_path, pack_index=self.index, pack_checksum=self.get_stored_checksum(), ) except ChecksumMismatch: # The bitmap records the checksum of the pack it was built for. # A mismatch means it is stale or was swapped in from another # pack, so its positions no longer describe this pack's objects. # Ignore it and let callers fall back to graph traversal, the # same as git. logger.warning( "Ignoring bitmap %s: checksum does not match pack", self._bitmap_path, ) return None return self._bitmap def ensure_bitmap( self, object_store: "BaseObjectStore", refs: dict["Ref", "ObjectID"], commit_interval: int | None = None, progress: Callable[[str], None] | None = None, ) -> "PackBitmap": """Ensure a bitmap exists for this pack, generating one if needed. Args: object_store: Object store to read objects from refs: Dictionary of ref names to commit SHAs commit_interval: Include every Nth commit in bitmap index progress: Optional progress reporting callback Returns: PackBitmap instance (either existing or newly generated) """ from .bitmap import generate_bitmap, write_bitmap # Check if bitmap already exists try: existing = self.bitmap if existing is not None: return existing except FileNotFoundError: pass # No bitmap, we'll generate one # Generate new bitmap if progress: progress(f"Generating bitmap for {self.name().decode('utf-8')}...\n") pack_bitmap = generate_bitmap( self.index, object_store, refs, self.get_stored_checksum(), commit_interval=commit_interval, progress=progress, ) # Write bitmap file write_bitmap(self._bitmap_path, pack_bitmap) if progress: progress(f"Wrote {self._bitmap_path}\n") # Update cached bitmap self._bitmap = pack_bitmap return pack_bitmap @property def mmap_size(self) -> int: """Return the total mmapped memory usage of this pack. This includes the pack data file and index file sizes, but only for components that have been loaded (and thus mmapped). """ total = 0 if self._data is not None: total += self._data._size if self._idx is not None and isinstance(self._idx, FilePackIndex): total += self._idx._size return total def close(self) -> None: """Close the pack file and index.""" if self._data is not None: self._data.close() self._data = None if self._idx is not None: self._idx.close() self._idx = None def __del__(self) -> None: """Ensure pack file is closed when Pack is garbage collected.""" if self._data is not None or self._idx is not None: import warnings warnings.warn( f"unclosed Pack {self!r}", ResourceWarning, stacklevel=2, source=self ) try: self.close() except Exception: # Ignore errors during cleanup pass def __enter__(self) -> Self: """Enter context manager.""" return self def __exit__( self, type: type | None, value: BaseException | None, traceback: TracebackType | None, ) -> None: """Exit context manager.""" self.close() def __eq__(self, other: object) -> bool: """Check equality with another pack.""" if not isinstance(other, Pack): return False return self.index == other.index def __len__(self) -> int: """Number of entries in this pack.""" return len(self.index) def __repr__(self) -> str: """Return string representation of this pack.""" return f"{self.__class__.__name__}({self._basename!r})" def __iter__(self) -> Iterator[ObjectID]: """Iterate over all the sha1s of the objects in this pack.""" return iter(self.index) def check_length_and_checksum(self) -> None: """Sanity check the length and checksum of the pack index and data.""" assert len(self.index) == len(self.data), ( f"Length mismatch: {len(self.index)} (index) != {len(self.data)} (data)" ) idx_stored_checksum = self.index.get_pack_checksum() data_stored_checksum = self.data.get_stored_checksum() if ( idx_stored_checksum is not None and idx_stored_checksum != data_stored_checksum ): raise ChecksumMismatch( sha_to_hex(RawObjectID(idx_stored_checksum)), sha_to_hex(RawObjectID(data_stored_checksum)), ) def check(self) -> None: """Check the integrity of this pack. Raises: ChecksumMismatch: if a checksum for the index or data is wrong """ self.index.check() self.data.check() for obj in self.iterobjects(): obj.check() # TODO: object connectivity checks def get_stored_checksum(self) -> bytes: """Return the stored checksum of the pack data.""" return self.data.get_stored_checksum() def pack_tuples(self) -> list[tuple[ShaFile, None]]: """Return pack tuples for all objects in pack.""" return [(o, None) for o in self.iterobjects()] def __contains__(self, sha1: ObjectID | RawObjectID) -> bool: """Check whether this pack contains a particular SHA1.""" try: self.index.object_offset(sha1) return True except KeyError: return False def get_raw(self, sha1: RawObjectID | ObjectID) -> tuple[int, bytes]: """Get raw object data by SHA1.""" offset = self.index.object_offset(sha1) obj_type, obj = self.data.get_object_at(offset) type_num, chunks = self.resolve_object(offset, obj_type, obj) return type_num, b"".join(chunks) # type: ignore[arg-type] def __getitem__(self, sha1: "ObjectID | RawObjectID") -> ShaFile: """Retrieve the specified SHA1.""" type, uncomp = self.get_raw(sha1) return ShaFile.from_raw_string(type, uncomp, sha=sha1) def iterobjects(self) -> Iterator[ShaFile]: """Iterate over the objects in this pack.""" return iter( PackInflater.for_pack_data(self.data, resolve_ext_ref=self.resolve_ext_ref) ) def iterobjects_subset( self, shas: Iterable[ObjectID], *, allow_missing: bool = False ) -> Iterator[ShaFile]: """Iterate over a subset of objects in this pack.""" return ( uo for uo in PackInflater.for_pack_subset( self, shas, allow_missing=allow_missing, resolve_ext_ref=self.resolve_ext_ref, ) if uo.id in shas ) def iter_unpacked_subset( self, shas: Iterable[ObjectID | RawObjectID], *, include_comp: bool = False, allow_missing: bool = False, convert_ofs_delta: bool = False, ) -> Iterator[UnpackedObject]: """Iterate over unpacked objects in subset.""" ofs_pending: dict[int, list[UnpackedObject]] = defaultdict(list) ofs: dict[int, bytes] = {} todo: set[ObjectID | RawObjectID] = set(shas) for unpacked in self.iter_unpacked(include_comp=include_comp): sha = unpacked.sha() if unpacked.offset is not None: ofs[unpacked.offset] = sha hexsha = sha_to_hex(RawObjectID(sha)) if hexsha in todo: if unpacked.pack_type_num == OFS_DELTA: assert isinstance(unpacked.delta_base, int) assert unpacked.offset is not None base_offset = unpacked.offset - unpacked.delta_base try: unpacked.delta_base = ofs[base_offset] except KeyError: ofs_pending[base_offset].append(unpacked) continue else: unpacked.pack_type_num = REF_DELTA yield unpacked todo.remove(hexsha) if unpacked.offset is not None: for child in ofs_pending.pop(unpacked.offset, []): child.pack_type_num = REF_DELTA child.delta_base = sha yield child assert not ofs_pending if not allow_missing and todo: raise UnresolvedDeltas(list(todo)) def iter_unpacked(self, include_comp: bool = False) -> Iterator[UnpackedObject]: """Iterate over all unpacked objects in this pack.""" ofs_to_entries = { ofs: (sha, crc32) for (sha, ofs, crc32) in self.index.iterentries() } for unpacked in self.data.iter_unpacked(include_comp=include_comp): assert unpacked.offset is not None (sha, crc32) = ofs_to_entries[unpacked.offset] unpacked._sha = sha unpacked.crc32 = crc32 yield unpacked def keep(self, msg: bytes | None = None) -> str: """Add a .keep file for the pack, preventing git from garbage collecting it. Args: msg: A message written inside the .keep file; can be used later to determine whether or not a .keep file is obsolete. Returns: The path of the .keep file, as a string. """ keepfile_name = f"{self._basename}.keep" with GitFile(keepfile_name, "wb") as keepfile: if msg: keepfile.write(msg) keepfile.write(b"\n") return keepfile_name def unkeep(self) -> bool: """Remove the .keep file for the pack, allowing git to garbage collect it. This is the counterpart of :meth:`keep`. It is not an error to call this on a pack that has no .keep file. Returns: True if a .keep file was removed, False if there was none. """ try: os.unlink(f"{self._basename}.keep") except FileNotFoundError: return False return True def get_ref( self, sha: RawObjectID | ObjectID ) -> tuple[int | None, int, OldUnpackedObject]: """Get the object for a ref SHA, only looking in this pack.""" # TODO: cache these results try: offset = self.index.object_offset(sha) except KeyError: offset = None if offset: type, obj = self.data.get_object_at(offset) elif self.resolve_ext_ref: type, obj = self.resolve_ext_ref(sha) else: raise KeyError(sha) return offset, type, obj def resolve_object( self, offset: int, type: int, obj: OldUnpackedObject, get_ref: Callable[ [RawObjectID | ObjectID], tuple[int | None, int, OldUnpackedObject] ] | None = None, ) -> tuple[int, OldUnpackedObject]: """Resolve an object, possibly resolving deltas when necessary. Returns: Tuple with object type and contents. """ # Walk down the delta chain, building a stack of deltas to reach # the requested object. base_offset: int | None = offset base_type = type base_obj = obj delta_stack = [] while base_type in DELTA_TYPES: prev_offset = base_offset if get_ref is None: get_ref = self.get_ref assert isinstance(base_obj, tuple), ( f"Expected delta tuple, got {base_obj.__class__.__name__}" ) if base_type == OFS_DELTA: (delta_offset, delta) = base_obj # TODO: clean up asserts and replace with nicer error messages assert isinstance(delta_offset, int), ( f"Expected int, got {delta_offset.__class__}" ) assert base_offset is not None base_offset = base_offset - delta_offset base_type, base_obj = self.data.get_object_at(base_offset) assert isinstance(base_type, int) elif base_type == REF_DELTA: (basename, delta) = base_obj assert ( isinstance(basename, bytes) and len(basename) == self.object_format.oid_length ) base_offset_temp, base_type, base_obj = get_ref(RawObjectID(basename)) assert isinstance(base_type, int) # base_offset_temp can be None for thin packs (external references) base_offset = base_offset_temp if base_offset == prev_offset: # object is based on itself raise UnresolvedDeltas([basename]) else: raise AssertionError(f"Unexpected delta type: {base_type}") delta_stack.append((prev_offset, base_type, delta)) # Now grab the base object (mustn't be a delta) and apply the # deltas all the way up the stack. chunks = base_obj for prev_offset, _delta_type, delta in reversed(delta_stack): # Convert chunks to bytes for apply_delta if needed if isinstance(chunks, list): chunks_bytes = b"".join(chunks) elif isinstance(chunks, tuple): # For tuple type, second element is the actual data _, chunk_data = chunks if isinstance(chunk_data, list): chunks_bytes = b"".join(chunk_data) else: chunks_bytes = chunk_data else: chunks_bytes = chunks # Apply delta and get result as list chunks = apply_delta(chunks_bytes, delta) if prev_offset is not None: self.data._cache_object_at(prev_offset, base_type, chunks) return base_type, chunks def entries( self, progress: Callable[[int, int], None] | None = None ) -> Iterator[PackIndexEntry]: """Yield entries summarizing the contents of this pack. Args: progress: Progress function, called with current and total object count. Returns: iterator of tuples with (sha, offset, crc32) """ return self.data.iterentries( progress=progress, resolve_ext_ref=self.resolve_ext_ref ) def sorted_entries( self, progress: Callable[[int, int], None] | None = None ) -> Iterator[PackIndexEntry]: """Return entries in this pack, sorted by SHA. Args: progress: Progress function, called with current and total object count Returns: Iterator of tuples with (sha, offset, crc32) """ return iter( self.data.sorted_entries( progress=progress, resolve_ext_ref=self.resolve_ext_ref ) ) def get_unpacked_object( self, sha: ObjectID | RawObjectID, *, include_comp: bool = False, convert_ofs_delta: bool = True, ) -> UnpackedObject: """Get the unpacked object for a sha. Args: sha: SHA of object to fetch include_comp: Whether to include compression data in UnpackedObject convert_ofs_delta: Whether to convert offset deltas to ref deltas """ offset = self.index.object_offset(sha) unpacked = self.data.get_unpacked_object_at(offset, include_comp=include_comp) if unpacked.pack_type_num == OFS_DELTA and convert_ofs_delta: assert isinstance(unpacked.delta_base, int) unpacked.delta_base = self.index.object_sha1(offset - unpacked.delta_base) unpacked.pack_type_num = REF_DELTA return unpacked def extend_pack( f: BinaryIO, object_ids: Set["RawObjectID"], get_raw: Callable[["RawObjectID | ObjectID"], tuple[int, bytes]], object_format: "ObjectFormat", *, compression_level: int = -1, progress: Callable[[bytes], None] | None = None, ) -> tuple[bytes, list[tuple[RawObjectID, int, int]]]: """Extend a pack file with more objects. The caller should make sure that object_ids does not contain any objects that are already in the pack """ # Update the header with the new number of objects. f.seek(0) _version, num_objects = read_pack_header(f.read) if object_ids: f.seek(0) write_pack_header(f.write, num_objects + len(object_ids)) # Must flush before reading (http://bugs.python.org/issue3207) f.flush() # Rescan the rest of the pack, computing the SHA with the new header. new_sha = compute_file_sha( f, hash_func=object_format.hash_func, end_ofs=-object_format.oid_length ) # Must reposition before writing (http://bugs.python.org/issue3207) f.seek(0, os.SEEK_CUR) extra_entries = [] # Complete the pack. for i, object_id in enumerate(object_ids): if progress is not None: progress( (f"writing extra base objects: {i}/{len(object_ids)}\r").encode("ascii") ) assert len(object_id) == object_format.oid_length type_num, data = get_raw(object_id) offset = f.tell() crc32 = write_pack_object( f.write, type_num, [data], # Convert bytes to list[bytes] sha=new_sha, compression_level=compression_level, object_format=object_format, ) extra_entries.append((object_id, offset, crc32)) pack_sha = new_sha.digest() f.write(pack_sha) return pack_sha, extra_entries try: from dulwich._pack import ( # type: ignore apply_delta, bisect_find_sha, ) except ImportError: pass # Try to import the Rust version of create_delta try: from dulwich._pack import create_delta as _create_delta_rs except ImportError: pass else: # Wrap the Rust version to match the Python API (returns bytes instead of Iterator) def _create_delta_rs_wrapper( base_buf: bytes | list[bytes], target_buf: bytes | list[bytes] ) -> Iterator[bytes]: """Wrapper for Rust create_delta to match Python API.""" if isinstance(base_buf, list): base_buf = b"".join(base_buf) if isinstance(target_buf, list): target_buf = b"".join(target_buf) yield _create_delta_rs(base_buf, target_buf) create_delta = _create_delta_rs_wrapper