Two latent bugs in every st.h reader, both hit in the field:
- a single pread caps at ~2^31 bytes on Linux, so any tensor past
2.1 GB (bf16 embed/unembed tensors of large models qualify) came
back silently truncated with perror printing '... : Success'
(errno untouched by a short read) — the same misleading-error
symptom glm.c fixed for its own reads in #236;
- no EINTR retry.
st_pread_full loops in ST_PREAD_CHUNK pieces (1 GB default, override
for tests), retries EINTR, and reports offset + progress on failure.
All five read sites converted; behavior on well-formed files is
byte-identical (GLM oracle re-verified on this branch: 32/32).
tests/test_st_pread builds with -DST_PREAD_CHUNK=7 so a 96-byte tensor
exercises the multi-chunk loop, and forks a child against a shard
truncated after st_init (init's static bounds check means the pread
path only fires when a file shrinks under a live handle) asserting
exit(1) with a 'short read' message and no 'Success'.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Nicholas Beerbower
6507817d9f