| """Explicit relocation of immutable metadata; source documents and hashes stay unchanged.""" |
| from __future__ import annotations |
|
|
| from collections.abc import Mapping, Sequence |
| from pathlib import Path |
| import os |
|
|
|
|
| class AssemblyPaths: |
| def __init__(self, root: Path, mappings: Mapping[str, str]) -> None: |
| if root.is_symlink(): |
| raise ValueError('assembly root symlink refused') |
| self.root = root.resolve(strict=True) |
| self.mappings = dict(mappings) |
| for old, relative in self.mappings.items(): |
| if not Path(old).is_absolute() or '..' in Path(old).parts: |
| raise ValueError('relocation source must be an absolute normalized path') |
| if Path(old) == Path('/') or self.root.is_relative_to(Path(old)): |
| raise ValueError('relocation source prefix contains assembly root or is /') |
| if Path(relative).is_absolute() or '..' in Path(relative).parts: |
| raise ValueError('relocation destination must be relative to assembly root') |
| self.inside(self.root / relative) |
|
|
| def inside(self, path: Path) -> Path: |
| path = Path(os.path.abspath(path)) |
| resolved = path.resolve(strict=True) |
| if not resolved.is_relative_to(self.root): |
| raise ValueError('identity path escapes assembly root: ' + str(path)) |
| |
| if any(p.is_symlink() for p in (path, *path.parents) if p.is_relative_to(self.root)): |
| raise ValueError('assembly identity symlink refused: ' + str(path)) |
| return resolved |
|
|
| def resolve(self, value: str) -> Path: |
| path = Path(value) |
| if not path.is_absolute() or '..' in path.parts: |
| raise ValueError('identity path must be absolute and normalized') |
| matches = [old for old in self.mappings if path.is_relative_to(Path(old))] |
| if matches: |
| old = max(matches, key=len) |
| path = self.root / self.mappings[old] / path.relative_to(old) |
| return self.inside(path) |
|
|
|
|
| def parse_mappings(values: Sequence[str]) -> dict[str, str]: |
| result: dict[str, str] = {} |
| for value in values: |
| old, sep, relative = value.partition('=') |
| if not sep or not old or not relative or old in result: |
| raise ValueError('path maps must be unique OLD_ABSOLUTE=ROOT_RELATIVE pairs') |
| result[old] = relative |
| return result |
|
|
