fix(format): skip user-defined links instead of failing the group

Link types 65-255 are user-defined: their target is only meaningful to
the application that registered the link class. LinkMessage::parse
rejects them with InvalidLinkType, and group traversal propagated that,
so one such link made the whole group unlistable and every path through
it unresolvable (libhdf5's tall.h5 and tudlink.h5, class 187).

Group traversal (compact and dense) now leaves user-defined links out,
the way h5py leaves out links it cannot open; reserved types (2-63) are
still an error.

Regression test: user_defined_links_do_not_break_the_listing, on
libhdf5's own tools/test/testfiles tall.h5 and tudlink.h5 (BSD-style
HDF5 licence, 10 KB and 1 KB), committed as fixtures.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
This commit is contained in:
osobh
2026-09-25 21:57:18 -05:00
co-authored by Claude Opus 5.5
parent 1c85986079
commit 38d0d4de02
6 changed files with 59 additions and 3 deletions
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