# Changelog
All notable changes to this project will be documented in this file.
The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
## [1.1.1] - 2026-05-10
### Fixed
- SIGBUS handler chains to the previously-installed handler when
fired outside any iommap-protected region. The earlier handler
always longjmped through a thread-local sigjmp_buf even when no
sigsetjmp had run, which caused process segfaults when iommap was
loaded alongside other NIFs that perform mmap I/O.
- SIGBUS handler no longer reads `__thread` storage on the signal
path. `iommap_nif.so` is loaded via `dlopen`, so on FreeBSD (and
any other platform whose dynamic loader allocates dlopened TLS
lazily) reading a `__thread` variable from a thread that has not
yet executed iommap code can call `__tls_get_addr`, which in turn
may call `malloc` -- not async-signal-safe, leading to a crash on
the next bus error. The protection state is now carried in a
`pthread_key_t` slot allocated eagerly by iommap NIF entry points;
the handler does a plain `pthread_getspecific` and treats a NULL
slot as "not in a protected region, chain to the previous
handler". This is the second half of the fix that made the
crashes only show up when iommap was paired with another NIF in
the same BEAM (the helper NIF was enough TLS pressure to push
iommap's slot out of the static-TLS reserve).
- `IOMMAP_MODE_WRITE` now opens the file `O_RDWR`. mmap with
PROT_WRITE requires a readable fd; the previous O_WRONLY broke
write-only mode at mmap time.
- `pread/3` and `region_binary/3` reject write-only handles with
`eacces`, matching the symmetric guard already in `pwrite/3`.
- `pwrite/3` now wraps its memcpy in the same enter/leave protected
pair as `pread/3` so a SIGBUS during pwrite is reported as
`{error, sigbus}` rather than chained to the default handler.
### Tests
- New `read_close_then_parse` and `many_open_close_cycles` cases
cover the read-only `open → region_binary → close → use binary`
pattern that downstream callers rely on.
- New `iommap_two_nif_tests` module reproduces the FreeBSD segfault
inside iommap. A test-only helper NIF (`test/c_src/`) registers
its own resource types alongside iommap; the test runs the
region_binary load pattern in a tight loop, both inline and from
a dedicated worker process. Without the TLS fix this reliably
crashed BEAM on FreeBSD 14.2 and 14.4 in CI; with the fix, all
matrix entries pass.
- FreeBSD CI now matrices 14.2 and 14.4.
## [1.1.0] - 2026-05-09
### Added
- `iommap:region_binary/3` returns a refcounted resource binary that
points directly into the mapped region, with no data copy. Intended
for hot zero-copy hand-off paths.
### Changed
- The NIF resource layout was split into a `mapping` resource (owns
the mmap region and fd) and a `handle` resource (owns the BEAM
handle term and one reference to the mapping). `close/1` releases
the handle's reference to the mapping; `munmap` and `close(fd)` are
deferred until any outstanding region binaries derived from that
mapping are also garbage collected. Existing API behaviour is
unchanged.
- `truncate/2` now allocates a fresh mapping (with a duplicated fd)
and atomically swaps it into the handle. The previous mapping
remains alive for outstanding region binaries.
### Notes
- `region_binary/3` is unsafe against external truncation that
shrinks past a binary's range. Use `pread/3` when safety against
external mutation is required.
## [1.0.0] - 2026-01-26
### Added
- Initial release of iommap
- Dirty NIF I/O schedulers for all I/O operations
- Cross-platform memory-mapped file I/O for Erlang/OTP
- Support for Linux, macOS, FreeBSD, and OpenBSD
- Core operations: `open/2,3`, `close/1`, `pread/3`, `pwrite/3`
- Synchronization: `sync/1,2` with sync/async modes
- File management: `truncate/2`, `position/1`
- Memory advice: `advise/4` with madvise hints
- Thread-safe implementation using pthread rwlocks
- SIGBUS protection for external file truncation
- Platform-specific optimizations:
- `MAP_POPULATE` support on Linux
- `MAP_NOCACHE` support on macOS
- `fallocate` on Linux, `posix_fallocate` on BSD
- Comprehensive test suite with 20 tests
- CI pipeline for all supported platforms
[1.1.0]: https://github.com/benoitc/erlang-iommap/releases/tag/1.1.0
[1.0.0]: https://github.com/benoitc/erlang-iommap/releases/tag/1.0.0
