fix: resolve shrunk DataMap in data_download#142
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Large uploads (more than 3 chunks, roughly >12 MiB) produce a shrunk (child) DataMap whose infos() reference wrapper chunks rather than the root content chunks. data_download handed those straight to self_encryption::decrypt, which unshrinks the root map internally but then fails fetching the root content chunks that were never requested, erroring with "Missing chunk: <hex>". Such blobs were unreadable through data_download even though the data was fully intact on the network; the data_upload/data_download primitive pair was asymmetric. Add resolve_root_data_map: when the map is a child, fetch the wrapper chunks and unshrink via self_encryption::get_root_data_map before downloading the root map's content chunks, mirroring how file_download already handles shrinking. Non-child maps are returned unchanged with no network access, so the common flat-map path is untouched. Add e2e regression test test_data_shrunk_datamap_round_trip using a 4 * MAX_CHUNK_SIZE payload that deterministically forces shrinking; confirmed it fails with the exact "Missing chunk" error without the fix. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The prior shrunk-DataMap fix introduced two issues on the public data_download API: - Its doc comment linked to the private resolve_root_data_map via an intra-doc link. cargo doc (run in CI with RUSTDOCFLAGS="-D warnings") rejects a public item linking to a private one, breaking the docs job. Reworded the doc to describe the behavior inline instead. - Resolving a shrunk map bridges self-encryption's synchronous fetcher onto the async network via block_in_place, which panics on a current-thread runtime. data_download thus panicked for large (shrunk) payloads while succeeding for small (flat) ones on the same runtime. A fully-async path isn't possible (self-encryption's per-level decrypt_full_set is pub(crate)), so keep the block_in_place bridge but guard it: ensure_shrunk_resolution_runtime maps a current-thread runtime to a descriptive Error::Config instead of panicking, and the requirement is now documented on the public method (mirroring file_download). Add unit tests covering both guard branches. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Summary
Large uploads (more than 3 chunks, roughly >12 MiB) produce a shrunk (child)
DataMapwhoseinfos()reference wrapper chunks rather than the root content chunks.data_downloadhanded those straight toself_encryption::decrypt, which unshrinks the root map internally but then fails fetching the root content chunks that were never requested, erroring withMissing chunk: <hex>.The result: any blob large enough to shrink was unreadable through
data_downloadeven though the data was fully intact on the network — thedata_upload/data_downloadprimitive pair was asymmetric. Small payloads (≤3 chunks, flat map) round-trip fine, which is why this hid in tests.Fix
resolve_root_data_map: when the map is a child, fetch the wrapper chunks and unshrink viaself_encryption::get_root_data_mapbefore downloading the root map's content chunks — mirroring howfile_downloadalready handles shrinking.Test plan
test_data_shrunk_datamap_round_tripuploads a4 * MAX_CHUNK_SIZEpayload that deterministically forces shrinking (assertsis_child()), then verifies a full byte-for-byte round-trip.Missing chunk: <hex>error, and passes with it.cargo clippy --all-targets --all-features -- -D warnings✅ ·cargo fmt --check✅ · fulle2e_datasuite (7 tests) ✅.🤖 Generated with Claude Code