# 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).
## [1.1.3] - 2026-05-10
### Fixed
- SIGBUS handler no longer stores the previous handler's function
pointer. `on_upgrade` re-ran `on_load`, which unconditionally
re-installed the handler and saved iommap's own `sigbus_handler` as
`original_sigbus_action`; the chain logic then recursed into itself
on the next out-of-protected SIGBUS. Even with self-recursion fixed,
storing the function pointer was unsafe across hot upgrade because
the captured pointer could land in another iommap DSO image and
dangle into freed text after `code:purge`. The handler now records
only a category (`PRIOR_DFL`, `PRIOR_IGN`, or `PRIOR_OTHER`) and
re-raises through a preinitialized `sigaction` template at signal
time. Install is one-shot per DSO and a new `on_unload` callback
restores `SIG_DFL` or `SIG_IGN` when iommap's handler is still
active. Trade-offs (no chaining to a third-party SIGBUS handler, no
third-party-handler restoration, single-DSO-lifetime `SIG_IGN`
preservation) are documented in `guides/features.md`.
- `iommap_handle_alloc` no longer calls `pthread_rwlock_destroy` on a
never-initialized lock when `pthread_rwlock_init` fails. A new
`rwlock_initialized` flag gates the destroy in the handle
destructor.
### Tests
- New `iommap_lifecycle_tests` module covers in-protected SIGBUS still
being caught after the handler rewrite, and a basic round-trip after
`code:load_file/1` (exercises the `on_upgrade` path).
## [1.1.2] - 2026-05-10
### Fixed
- 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 SIGBUS-handler fix
started in 1.1.1; the crash only showed up when iommap was
paired with another NIF in the same BEAM (enough TLS pressure
to push iommap's slot out of the static-TLS reserve).
### Tests
- 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.
## [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.
- `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.
- 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
