Add utils/media_capture.py: CaptureStore copies one rooted media file
into an owner-only prompt-manager-captures-* temp directory, streaming
it in 1 MiB chunks while computing the whole-file SHA-256, and compares
the opened descriptor with the path (dev, ino where meaningful, size,
mtime_ns, ctime_ns) before and after the copy; any disagreement raises
CaptureChanged and removes the copy. Symlinked files or directories,
root escapes, non-media names and directories raise CaptureDenied; the
locator is normcase(join(realpath(root), relative)), the listing's
identity, so a symlinked root matches it.
Limits are the plan's: 256 MiB per file on stat and stream
(CaptureTooLarge), 8 completed captures, 512 MiB reserved and 2
capture/verify workers with nonblocking admission (CaptureCapacity),
900 s idle and 1800 s hard lifetimes on an injected clock. acquire and
release_use keep an in-use capture past expiry, release and
invalidate_all until its last use ends; close removes only owned files
and the owned directory. A header-only probe of the copy marks Generate
unsupported above 4096 px per side or 16,777,216 px, for unreadable
headers and for video; verify re-hashes the current file without a
copy. Every handle closes before unlink.
tests/test_media_capture.py covers exact bytes and owner-only modes,
alias and escape denial, the symlinked-root locator, change detection
during the copy (size, same-size rewrite with restored mtime through
the POSIX change time, inode replacement), both size caps, count, byte
and worker admission, idle and hard expiry with in-use retention,
cleanup scope, handle release at unlink, dimension and video
readiness, and the allowlist equality with the inspection service.
TESTING.md documents the store and the Windows change-time limit.
Vito Sansevero
a3d5c16318