feat: add columnar-dbc Rust crates linking dbc statically

.gitignore

@@ -49,3 +49,7 @@ cdn-dev
 .claude
 
 __pycache__
+
+# Rust crates (rust/); native/ holds libdbc.a/libdbc.h (local go build or GoReleaser's stage_capi.py)
+rust/target/
+rust/platforms/*/native/

CONTRIBUTING.md

@@ -30,6 +30,73 @@ and you can run the tests by running,
 go test -v ./...
 ```
 
+### C API and Rust crates
+
+`./capi` is dbc's C API. cgo generates its header, `libdbc.h`, from the
+preamble and `//export` functions in `capi/exports.go`, so that file is the
+only place the API is declared. The Rust crates in `rust/` link a bundled
+static build by default, or a system/custom library as described below.
+Building libdbc needs a C compiler (cgo) as well as Go; using the Rust crates
+also needs Rust. For bundled linking, build the archive for your platform
+(`linux-x64`, `linux-arm64`, `darwin-x64`, `darwin-arm64`, or `windows-x64`)
+into its platform crate, then run the tests:
+
+```sh
+CGO_ENABLED=1 go build -tags netgo,osusergo -buildmode=c-archive -o rust/platforms/linux-x64/native/libdbc.a ./capi
+cargo test --manifest-path rust/Cargo.toml -p columnar-dbc
+```
+
+#### Linking a system libdbc
+
+To test against a custom static build without staging a platform crate:
+
+```sh
+mkdir -p /tmp/dbc-local/lib
+CGO_ENABLED=1 go build -tags netgo,osusergo -buildmode=c-archive -o /tmp/dbc-local/lib/libdbc.a ./capi
+DBC_SYS_LIB_DIR=/tmp/dbc-local/lib cargo test --manifest-path rust/Cargo.toml -p columnar-dbc --no-default-features
+```
+
+Alternatively, install `libdbc-dev` (Debian/Ubuntu) or `libdbc-devel` (RPM),
+along with the `pkg-config` executable. For example, use
+`sudo apt install ./libdbc-dev_*.deb` for a downloaded Debian package.
+These packages provide the static and shared libraries, header, and `dbc.pc`.
+Then run:
+
+```sh
+cargo test --manifest-path rust/Cargo.toml -p columnar-dbc --no-default-features --features pkg-config
+```
+
+Set `PKG_CONFIG_PATH` to the directory containing `dbc.pc` if it is not in
+the system search path. Disabling default features avoids downloading or
+building the bundled platform crates. Source precedence is `DBC_SYS_LIB_DIR`,
+then the `pkg-config` feature or presence of `DBC_SYS_USE_PKG_CONFIG`, then
+the default `bundled` feature; environment overrides also work with default
+features still enabled. With no source selected, the build fails.
+
+System/custom linking defaults to static. Set `DBC_DYNAMIC` (any value,
+including empty) for dynamic linking; bundled linking remains static.
+To test a custom shared build on Linux:
+
+```sh
+CGO_ENABLED=1 go build -tags netgo,osusergo -buildmode=c-shared -ldflags '-extldflags "-Wl,-soname,libdbc.so"' -o /tmp/dbc-local/lib/libdbc.so ./capi
+DBC_SYS_LIB_DIR=/tmp/dbc-local/lib DBC_DYNAMIC=1 LD_LIBRARY_PATH=/tmp/dbc-local/lib cargo test --manifest-path rust/Cargo.toml -p columnar-dbc --no-default-features
+```
+
+Dynamic linking requires `libdbc.so` on the runtime loader's search path;
+the crate does not configure it. See the
+[Rust crate README](rust/columnar-dbc/README.md#linking-a-system-libdbc)
+for dependency configuration.
+
+#### Regenerating Rust bindings
+
+After changing anything in `capi/exports.go`, regenerate the Rust bindings
+with bindgen-cli 0.73.2 (CI fails if they are stale):
+
+```sh
+cargo install bindgen-cli --version 0.73.2 --locked
+python3 scripts/gen_rust_bindings.py rust/platforms/linux-x64/native/libdbc.h
+```
+
 ## Debugging
 
 Debugging dbc can be done similarly to any Golang project and editor setups like VSCode with the official Go extension should work out of the box.

rust/Cargo.toml

@@ -0,0 +1,36 @@
+# Copyright 2026 Columnar Technologies Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+[workspace]
+resolver = "2"
+members = ["columnar-dbc", "columnar-dbc-sys", "platforms/*"]
+
+[workspace.package]
+# Placeholder: scripts/publish_crates.py stamps the release version here and
+# in the pins below while packaging/publishing. Every crate ships with the
+# dbc release version.
+version = "0.0.0-dev"
+edition = "2021"
+rust-version = "1.82"
+license = "Apache-2.0"
+repository = "https://github.com/columnar-tech/dbc"
+homepage = "https://columnar.tech/dbc"
+
+[workspace.dependencies]
+columnar-dbc-sys = { path = "columnar-dbc-sys", version = "=0.0.0-dev", default-features = false }
+columnar-dbc-sys-linux-x64 = { path = "platforms/linux-x64", version = "=0.0.0-dev" }
+columnar-dbc-sys-linux-arm64 = { path = "platforms/linux-arm64", version = "=0.0.0-dev" }
+columnar-dbc-sys-darwin-x64 = { path = "platforms/darwin-x64", version = "=0.0.0-dev" }
+columnar-dbc-sys-darwin-arm64 = { path = "platforms/darwin-arm64", version = "=0.0.0-dev" }
+columnar-dbc-sys-windows-x64 = { path = "platforms/windows-x64", version = "=0.0.0-dev" }

rust/columnar-dbc-sys/Cargo.toml

@@ -0,0 +1,55 @@
+# Copyright 2026 Columnar Technologies Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+[package]
+name = "columnar-dbc-sys"
+description = "Raw FFI bindings to dbc's C ABI with bundled or system linking. Use columnar-dbc instead."
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+repository.workspace = true
+homepage.workspace = true
+# Two copies of the Go runtime in one binary would collide at link time;
+# `links` makes Cargo reject that during resolution instead.
+links = "columnar_dbc"
+build = "build.rs"
+
+[features]
+default = ["bundled"]
+bundled = [
+    "dep:columnar-dbc-sys-linux-x64",
+    "dep:columnar-dbc-sys-linux-arm64",
+    "dep:columnar-dbc-sys-darwin-x64",
+    "dep:columnar-dbc-sys-darwin-arm64",
+    "dep:columnar-dbc-sys-windows-x64",
+]
+pkg-config = []
+
+[build-dependencies]
+pkg-config = "0.3"
+
+[target.'cfg(all(target_os = "linux", target_arch = "x86_64", target_env = "gnu"))'.dependencies]
+columnar-dbc-sys-linux-x64 = { workspace = true, optional = true }
+
+[target.'cfg(all(target_os = "linux", target_arch = "aarch64", target_env = "gnu"))'.dependencies]
+columnar-dbc-sys-linux-arm64 = { workspace = true, optional = true }
+
+[target.'cfg(all(target_os = "macos", target_arch = "x86_64"))'.dependencies]
+columnar-dbc-sys-darwin-x64 = { workspace = true, optional = true }
+
+[target.'cfg(all(target_os = "macos", target_arch = "aarch64"))'.dependencies]
+columnar-dbc-sys-darwin-arm64 = { workspace = true, optional = true }
+
+[target.'cfg(all(target_os = "windows", target_arch = "x86_64"))'.dependencies]
+columnar-dbc-sys-windows-x64 = { workspace = true, optional = true }