fix(format): locate the address in version-1 shared messages

A version-1 shared message reference is version, type, six reserved bytes and then an old-style symbol table entry: link-name offset (length size), object header address, cache type, reserved, scratch. We read the address straight after the reserved bytes, i.e. the link-name offset, and the committed datatype lookup failed with InvalidObjectHeaderVersion (the bytes checked in tcompound.h5: name offset 0x10, then 0x590 = /type1). Datasets of 1.4/1.6-era files that use a committed datatype were unreadable. Skip the name offset. parse_shared_ref has no length size, so add parse_shared_ref_sized and use it in every internal caller; parse_shared_ref keeps its signature and assumes length size == offset size. The old parse_v1_ref unit test encoded the wrong layout and now uses the real bytes. Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
2026-09-25 21:55:31 -05:00
parent 36356ba8a1
commit c7092722aa
7 changed files with 127 additions and 13 deletions
@@ -10,3 +10,4 @@ write these structures, so they are kept as files.
 | `deflate.h5` | `test/testfiles/deflate.h5` | Data Layout message v1, chunked + deflate (v1 B-tree index) |
 | `h5ex_g_iterate.h5` | `HDF5Examples/C/H5G/h5ex_g_iterate.h5` | Data Layout message v2, contiguous; an unallocated dataset |
 | `tarrold.h5` | `test/testfiles/tarrold.h5` | Compound datatype v1 members with legacy array dimensions |
+| `tcompound.h5` | `tools/test/testfiles/tcompound.h5` | Version-1 shared messages (committed datatypes); compound v1 array members with data |