Background threads (spawn_indexer, spawn_visual_height_rebuild) previously
held mmap during entire file scan, risking SIGBUS if file was truncated
externally. Now uses BufReader streaming scan with mmap created only
after scan completes, plus stat validation.
Changes:
- spawn_indexer: replace mmap scan with BufReader fill_buf/consume loop,
create mmap post-scan with fd stat validation
- spawn_visual_height_rebuild: replace mmap/FileReader with sequential
BufReader scan, discard results on line count mismatch
- FileReader::open/reload/update_for_append: add stat-after-mmap check
- LineIndex: make fields pub(crate) for direct construction from scan loop
- Add 3 regression tests for truncation scenarios
spawn_indexer builds LineIndex from mmap snapshot but IndexCache::save()
re-opened the file to compute the hash. If the file changed between those
two steps, the cached index would be stored under the wrong hash.
- Add IndexCache::save_with_hash() that computes hash from in-memory data
- Add compute_data_hash() public function (same algorithm as compute_file_hash)
- Update spawn_indexer, FileReader::save_cache, and test callers
Replace direct indexing with .get()? to return None instead of panicking
when sampled_offsets is shorter than expected (e.g. corrupt bincode cache).
Closes#3
Replace LineIndex::from_reader(BufReader) with LineIndex::from_bytes(&mmap)
in both open() and reload(), ensuring the line index is always built from
the same mmap snapshot rather than a separate read through the file descriptor.
This closes the race window where an external file modification between
mmap() and from_reader() could cause line_index offsets to disagree with
the mmap data, leading to get_line() returning wrong content or panicking.
Closes#2
File truncation/rotation during mmap lifetime caused SIGBUS crash
because update_for_append() ignored new_size < old_size, leaving
a stale mapping that would fault on access.
Introduce AppendStatus enum (Unchanged/Appended/Reloaded) so the
caller can distinguish shrink events from normal appends. On shrink,
reload() rebuilds the mmap and line index. The TUI layer clamps
cursor and invalidates viewport cache on Reloaded, matching the
existing handle_file_truncated() behavior.
Fixes#1
dailz