Source code for swh.model.from_disk

# Copyright (C) 2017-2020 The Software Heritage developers
# See the AUTHORS file at the top-level directory of this distribution
# License: GNU General Public License version 3, or any later version
# See top-level LICENSE file for more information

import datetime
import enum
import fnmatch
import glob
import os
import re
import stat
from typing import Any, Iterable, Iterator, List, Optional, Pattern, Tuple

import attr
from attrs_strict import type_validator
from typing_extensions import Final

from . import model
from .exceptions import InvalidDirectoryPath
from .hashutil import MultiHash
from .identifiers import directory_entry_sort_key, directory_identifier
from .identifiers import identifier_to_bytes as id_to_bytes
from .identifiers import identifier_to_str as id_to_str
from .merkle import MerkleLeaf, MerkleNode


[docs]@attr.s(frozen=True, slots=True) class DiskBackedContent(model.BaseContent): """Content-like class, which allows lazy-loading data from the disk.""" object_type: Final = "content_file" sha1 = attr.ib(type=bytes, validator=type_validator()) sha1_git = attr.ib(type=model.Sha1Git, validator=type_validator()) sha256 = attr.ib(type=bytes, validator=type_validator()) blake2s256 = attr.ib(type=bytes, validator=type_validator()) length = attr.ib(type=int, validator=type_validator()) status = attr.ib( type=str, validator=attr.validators.in_(["visible", "hidden"]), default="visible", ) ctime = attr.ib( type=Optional[datetime.datetime], validator=type_validator(), default=None, eq=False, ) path = attr.ib(type=Optional[bytes], default=None)
[docs] @classmethod def from_dict(cls, d): return cls(**d)
def __attrs_post_init__(self): if self.path is None: raise TypeError("path must not be None.")
[docs] def with_data(self) -> model.Content: args = self.to_dict() del args["path"] assert self.path is not None with open(self.path, "rb") as fd: return model.Content.from_dict({**args, "data": fd.read()})
[docs]class DentryPerms(enum.IntEnum): """Admissible permissions for directory entries.""" content = 0o100644 """Content""" executable_content = 0o100755 """Executable content (e.g. executable script)""" symlink = 0o120000 """Symbolic link""" directory = 0o040000 """Directory""" revision = 0o160000 """Revision (e.g. submodule)"""
[docs]def mode_to_perms(mode): """Convert a file mode to a permission compatible with Software Heritage directory entries Args: mode (int): a file mode as returned by :func:`os.stat` in :attr:`os.stat_result.st_mode` Returns: DentryPerms: one of the following values: :const:`DentryPerms.content`: plain file :const:`DentryPerms.executable_content`: executable file :const:`DentryPerms.symlink`: symbolic link :const:`DentryPerms.directory`: directory """ if stat.S_ISLNK(mode): return DentryPerms.symlink if stat.S_ISDIR(mode): return DentryPerms.directory else: # file is executable in any way if mode & (0o111): return DentryPerms.executable_content else: return DentryPerms.content
[docs]class Content(MerkleLeaf): """Representation of a Software Heritage content as a node in a Merkle tree. The current Merkle hash for the Content nodes is the `sha1_git`, which makes it consistent with what :class:`Directory` uses for its own hash computation. """ __slots__ = [] # type: List[str] object_type: Final = "content"
[docs] @classmethod def from_bytes(cls, *, mode, data): """Convert data (raw :class:`bytes`) to a Software Heritage content entry Args: mode (int): a file mode (passed to :func:`mode_to_perms`) data (bytes): raw contents of the file """ ret = MultiHash.from_data(data).digest() ret["length"] = len(data) ret["perms"] = mode_to_perms(mode) ret["data"] = data ret["status"] = "visible" return cls(ret)
[docs] @classmethod def from_file(cls, *, path, max_content_length=None): """Compute the Software Heritage content entry corresponding to an on-disk file. The returned dictionary contains keys useful for both: - loading the content in the archive (hashes, `length`) - using the content as a directory entry in a directory Args: save_path (bool): add the file path to the entry max_content_length (Optional[int]): if given, all contents larger than this will be skipped. """ file_stat = os.lstat(path) mode = file_stat.st_mode length = file_stat.st_size too_large = max_content_length is not None and length > max_content_length if stat.S_ISLNK(mode): # Symbolic link: return a file whose contents are the link target if too_large: # Unlike large contents, we can't stream symlinks to # MultiHash, and we don't want to fit them in memory if # they exceed max_content_length either. # Thankfully, this should not happen for reasonable values of # max_content_length because of OS/filesystem limitations, # so let's just raise an error. raise Exception(f"Symlink too large ({length} bytes)") return cls.from_symlink(path=path, mode=mode) elif not stat.S_ISREG(mode): # not a regular file: return the empty file instead return cls.from_bytes(mode=mode, data=b"") if too_large: skip_reason = "Content too large" else: skip_reason = None hashes = MultiHash.from_path(path).digest() if skip_reason: ret = { **hashes, "status": "absent", "reason": skip_reason, } else: ret = { **hashes, "status": "visible", } ret["path"] = path ret["perms"] = mode_to_perms(mode) ret["length"] = length obj = cls(ret) return obj
def __repr__(self): return "Content(id=%s)" % id_to_str(self.hash)
[docs] def compute_hash(self): return self.data["sha1_git"]
[docs] def to_model(self) -> model.BaseContent: """Builds a `model.BaseContent` object based on this leaf.""" data = self.get_data().copy() data.pop("perms", None) if data["status"] == "absent": data.pop("path", None) return model.SkippedContent.from_dict(data) elif "data" in data: return model.Content.from_dict(data) else: return DiskBackedContent.from_dict(data)
[docs]def accept_all_directories(dirpath: str, dirname: str, entries: Iterable[Any]) -> bool: """Default filter for :func:`Directory.from_disk` accepting all directories Args: dirname (bytes): directory name entries (list): directory entries """ return True
[docs]def ignore_empty_directories( dirpath: str, dirname: str, entries: Iterable[Any] ) -> bool: """Filter for :func:`directory_to_objects` ignoring empty directories Args: dirname (bytes): directory name entries (list): directory entries Returns: True if the directory is not empty, false if the directory is empty """ return bool(entries)
[docs]def ignore_named_directories(names, *, case_sensitive=True): """Filter for :func:`directory_to_objects` to ignore directories named one of names. Args: names (list of bytes): names to ignore case_sensitive (bool): whether to do the filtering in a case sensitive way Returns: a directory filter for :func:`directory_to_objects` """ if not case_sensitive: names = [name.lower() for name in names] def named_filter( dirpath: str, dirname: str, entries: Iterable[Any], names: Iterable[Any] = names, case_sensitive: bool = case_sensitive, ): if case_sensitive: return dirname not in names else: return dirname.lower() not in names return named_filter
# TODO: `extract_regex_objs` has been copied and adapted from `swh.scanner`. # In the future `swh.scanner` should use the `swh.model` version and remove its own.
[docs]def extract_regex_objs( root_path: bytes, patterns: Iterable[bytes] ) -> Iterator[Pattern[bytes]]: """Generates a regex object for each pattern given in input and checks if the path is a subdirectory or relative to the root path. Args: root_path (bytes): path to the root directory patterns (list of byte): patterns to match Yields: an SRE_Pattern object """ absolute_root_path = os.path.abspath(root_path) for pattern in patterns: for path in glob.glob(pattern): absolute_path = os.path.abspath(path) if not absolute_path.startswith(absolute_root_path): error_msg = ( b'The path "' + path + b'" is not a subdirectory or relative ' b'to the root directory path: "' + root_path + b'"' ) raise InvalidDirectoryPath(error_msg) regex = fnmatch.translate((pattern.decode())) yield re.compile(regex.encode())
[docs]def ignore_directories_patterns(root_path: bytes, patterns: Iterable[bytes]): """Filter for :func:`directory_to_objects` to ignore directories matching certain patterns. Args: root_path (bytes): path of the root directory patterns (list of byte): patterns to ignore Returns: a directory filter for :func:`directory_to_objects` """ sre_patterns = set(extract_regex_objs(root_path, patterns)) def pattern_filter( dirpath: bytes, dirname: bytes, entries: Iterable[Any], patterns: Iterable[Any] = sre_patterns, root_path: bytes = os.path.abspath(root_path), ): full_path = os.path.abspath(dirpath) relative_path = os.path.relpath(full_path, root_path) return not any([pattern.match(relative_path) for pattern in patterns]) return pattern_filter
[docs]def iter_directory( directory, ) -> Tuple[List[model.Content], List[model.SkippedContent], List[model.Directory]]: """Return the directory listing from a disk-memory directory instance. Raises: TypeError in case an unexpected object type is listed. Returns: Tuple of respectively iterable of content, skipped content and directories. """ contents: List[model.Content] = [] skipped_contents: List[model.SkippedContent] = [] directories: List[model.Directory] = [] for obj in directory.iter_tree(): obj = obj.to_model() obj_type = obj.object_type if obj_type in (model.Content.object_type, DiskBackedContent.object_type): # FIXME: read the data from disk later (when the # storage buffer is flushed). obj = obj.with_data() contents.append(obj) elif obj_type == model.SkippedContent.object_type: skipped_contents.append(obj) elif obj_type == model.Directory.object_type: directories.append(obj) else: raise TypeError(f"Unexpected object type from disk: {obj}") return contents, skipped_contents, directories
[docs]class Directory(MerkleNode): """Representation of a Software Heritage directory as a node in a Merkle Tree. This class can be used to generate, from an on-disk directory, all the objects that need to be sent to the Software Heritage archive. The :func:`from_disk` constructor allows you to generate the data structure from a directory on disk. The resulting :class:`Directory` can then be manipulated as a dictionary, using the path as key. The :func:`collect` method is used to retrieve all the objects that need to be added to the Software Heritage archive since the last collection, by class (contents and directories). When using the dict-like methods to update the contents of the directory, the affected levels of hierarchy are reset and can be collected again using the same method. This enables the efficient collection of updated nodes, for instance when the client is applying diffs. """ __slots__ = ["__entries"] object_type: Final = "directory"
[docs] @classmethod def from_disk( cls, *, path, dir_filter=accept_all_directories, max_content_length=None ): """Compute the Software Heritage objects for a given directory tree Args: path (bytes): the directory to traverse data (bool): whether to add the data to the content objects save_path (bool): whether to add the path to the content objects dir_filter (function): a filter to ignore some directories by name or contents. Takes two arguments: dirname and entries, and returns True if the directory should be added, False if the directory should be ignored. max_content_length (Optional[int]): if given, all contents larger than this will be skipped. """ top_path = path dirs = {} for root, dentries, fentries in os.walk(top_path, topdown=False): entries = {} # Join fentries and dentries in the same processing, as symbolic # links to directories appear in dentries... for name in fentries + dentries: path = os.path.join(root, name) if not os.path.isdir(path) or os.path.islink(path): content = Content.from_file( path=path, max_content_length=max_content_length ) entries[name] = content else: if dir_filter(path, name, dirs[path].entries): entries[name] = dirs[path] dirs[root] = cls({"name": os.path.basename(root)}) dirs[root].update(entries) return dirs[top_path]
def __init__(self, data=None): super().__init__(data=data) self.__entries = None
[docs] def invalidate_hash(self): self.__entries = None super().invalidate_hash()
[docs] @staticmethod def child_to_directory_entry(name, child): if child.object_type == "directory": return { "type": "dir", "perms": DentryPerms.directory, "target": child.hash, "name": name, } elif child.object_type == "content": return { "type": "file", "perms": child.data["perms"], "target": child.hash, "name": name, } else: raise ValueError(f"unknown child {child}")
[docs] def get_data(self, **kwargs): return { "id": self.hash, "entries": self.entries, }
@property def entries(self): """Child nodes, sorted by name in the same way `directory_identifier` does.""" if self.__entries is None: self.__entries = sorted( ( self.child_to_directory_entry(name, child) for name, child in self.items() ), key=directory_entry_sort_key, ) return self.__entries
[docs] def compute_hash(self): return id_to_bytes(directory_identifier({"entries": self.entries}))
[docs] def to_model(self) -> model.Directory: """Builds a `model.Directory` object based on this node; ignoring its children.""" return model.Directory.from_dict(self.get_data())
def __getitem__(self, key): if not isinstance(key, bytes): raise ValueError("Can only get a bytes from Directory") # Convenience shortcut if key == b"": return self if b"/" not in key: return super().__getitem__(key) else: key1, key2 = key.split(b"/", 1) return self.__getitem__(key1)[key2] def __setitem__(self, key, value): if not isinstance(key, bytes): raise ValueError("Can only set a bytes Directory entry") if not isinstance(value, (Content, Directory)): raise ValueError( "Can only set a Directory entry to a Content or " "Directory" ) if key == b"": raise ValueError("Directory entry must have a name") if b"\x00" in key: raise ValueError("Directory entry name must not contain nul bytes") if b"/" not in key: return super().__setitem__(key, value) else: key1, key2 = key.rsplit(b"/", 1) self[key1].__setitem__(key2, value) def __delitem__(self, key): if not isinstance(key, bytes): raise ValueError("Can only delete a bytes Directory entry") if b"/" not in key: super().__delitem__(key) else: key1, key2 = key.rsplit(b"/", 1) del self[key1][key2] def __repr__(self): return "Directory(id=%s, entries=[%s])" % ( id_to_str(self.hash), ", ".join(str(entry) for entry in self), )