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generator/input_audit.py

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+"""Composition read boundary, independent of optional audition/reference tools."""
+from __future__ import annotations
+import contextlib
+import contextvars
+import os
+from pathlib import Path
+import sys
+
+ACTIVE=contextvars.ContextVar('composition_reads',default=None)
+
+
+def _read(event,args):
+  scope=ACTIVE.get()
+  if scope is None or event!='open':return
+  name,mode,flags=args
+  if not isinstance(name,(str,bytes,os.PathLike)):return
+  # r+ and w+ can read; they must obey the same boundary as a plain read.
+  if flags & os.O_WRONLY:return
+  path=Path(os.fsdecode(name)).resolve()
+  data,code,cache,reads=scope
+  python_runtime=any(path.is_relative_to(Path(root).resolve()) for root in (sys.base_prefix,sys.prefix))
+  allowed=path.is_relative_to(data) or path.is_relative_to(code) or python_runtime
+  if cache and path.is_relative_to(cache):allowed=True
+  if not allowed:raise ValueError('Forbidden composition input: '+str(path))
+  reads.add(str(path))
+
+
+sys.addaudithook(_read)
+
+
+@contextlib.contextmanager
+def composition(data,role,cache=None):
+  reads=set()
+  code=Path(__file__).resolve().parent
+  token=ACTIVE.set((Path(data).resolve(),code,Path(cache).resolve()/role if cache else None,reads))
+  try:yield reads
+  finally:ACTIVE.reset(token)