50 lines
1.7 KiB
Python
50 lines
1.7 KiB
Python
import os
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from pathlib import Path
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DEFAULT_LEFT4ME_ROOT = Path("/var/lib/left4me")
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def get_left4me_root() -> Path:
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raw = os.environ.get("LEFT4ME_ROOT")
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if raw is None:
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return DEFAULT_LEFT4ME_ROOT
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root = raw.strip()
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if not root:
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raise ValueError("LEFT4ME_ROOT must not be empty")
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if root != raw:
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raise ValueError("LEFT4ME_ROOT must not contain leading or trailing whitespace")
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path = Path(root)
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if not path.is_absolute():
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raise ValueError("LEFT4ME_ROOT must be absolute")
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return path
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def validate_overlay_ref(ref: str) -> str:
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stripped = ref.strip()
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if stripped != ref:
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raise ValueError("overlay ref must not contain leading or trailing whitespace")
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if stripped in {"", ".", ".."}:
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raise ValueError("overlay ref must not be empty or current/parent directory")
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if Path(stripped).is_absolute():
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raise ValueError("overlay ref must be relative")
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components = stripped.split("/")
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if any(component in {"", ".", ".."} for component in components):
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raise ValueError("overlay ref must not contain empty, current, or parent components")
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return stripped
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def overlay_path(ref: str, *, root: Path | None = None) -> Path:
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safe_ref = validate_overlay_ref(ref)
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left4me_root = get_left4me_root() if root is None else Path(root)
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overlays_root = left4me_root / "overlays"
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candidate = overlays_root / safe_ref
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resolved_overlays_root = overlays_root.resolve()
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resolved_candidate = candidate.resolve()
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if resolved_candidate != resolved_overlays_root and resolved_overlays_root not in resolved_candidate.parents:
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raise ValueError("overlay path escapes overlay root")
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return candidate
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