openbim-ifc-capi

Versioned, memory-safe C ABI for openbim-ifc: read, edit and write IFC STEP files from C and C++.

Status	Partial
Latest release	not released (main is 0.1.0)
Registries	not published yet; build from source
API documentation	rustdoc
Source	crates/openbim-ifc-capi/

Overview

Versioned C ABI for the IFC facade (ADR 0013, #38).

Every export is prefixed openbim_ifc_v0_1_ and follows the conventions of Axiolid's C ABI (its ADR 0040), so a native host can use both the same way:

• Models are opaque non-zero u64 handles, never Rust addresses. A stale or twice-destroyed handle is OpenbimIfcStatus::InvalidHandle.
• The caller owns every output buffer. Each such call writes the size it needs to out_required first; a null buffer with capacity 0 is the size query, and a short buffer is OpenbimIfcStatus::BufferTooSmall. No Rust allocation crosses the boundary, so there is no free function.
• Every export runs inside catch_unwind; a panic becomes OpenbimIfcStatus::Panic and never unwinds into C.
• C integers are validated as integers, never read as Rust enums.

Attribute values cross as a value tape: a flat pre-order array of OpenbimIfcValueNode plus one byte buffer holding every string. See tape for the encoding, which carries the same kinds as the other bindings so $/*, .U./.F. and typed wrappers stay distinct.

Reading and writing caller-provided C buffers cannot be done without unsafe, so this crate's unsafe surface is its whole export set. It is not the only unsafe code in the workspace: the opt-in memory-mapped read (ifc_step::StepReader::read_path_mapped, wrapped by openbim-ifc-binding-core and openbim-ifc-py) is an unsafe fn too, because another process may change a mapped file. Here, each dereference sits in buffer or directly beside its null/length check, with a SAFETY comment.

The conventions above mirror Axiolid's ADR 0040 on purpose. A divergence needs its reason recorded in the module docs or an ADR. ABI 0.1 symbols are frozen once released: a change adds openbim_ifc_v0_2_ exports rather than altering a v0_1_ one.

Features

Feature	Default	Enables
rusty_alloc		dep:rusty_alloc-api, dep:rusty_alloc

Depends on

• openbim-ifc-binding-core

Changes

Full history: crates/openbim-ifc-capi/CHANGELOG.md