fix(format): size fractal heap child indirect blocks by their row's span

A child indirect block in row r of a fractal heap's doubling table spans that row's block size of heap space, so it has log2(size) - log2(start_block_size * width) + 1 rows (libhdf5's H5HF__dtable_size_to_rows). The reader used row - first_indirect_row + 1, which undercounts, so every object stored past the root block's direct rows (512 KiB with libhdf5's defaults) was unreachable: dense groups with a few thousand long link names, or ~20 000 short ones, could not be listed. Regression test: dense_group_whose_heap_outgrows_the_root_direct_rows (h5py writes 2 500 links with 248-byte names; listing compared with h5py). Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
2026-09-25 21:52:07 -05:00
parent 42b81d9f1c
commit 8ebd488d9e
4 changed files with 183 additions and 33 deletions
@@ -77,6 +77,8 @@ the VDS item, which is marked.
 - **Groups and links:**
  - Groups with a user-defined link type (e.g. 187) cannot be listed.
  - Dense groups with more than about 22 000 links cannot be listed.
+    *Partly fixed 2026-09-25:* a link heap past its root block's direct rows
+    (child indirect blocks) is now read.
  - Soft links are left out of `datasets()`.
 - **Dense attributes:** a large attribute stored as a fractal-heap "huge"
  object makes every attribute on the object fail. This affects real NetCDF