Calling Rust

Exporting Rust functions and types to C is easy:

interoperability/rust/libanalyze/analyze.rs

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interoperability/rust/libanalyze/analyze.h

#ifndef ANALYSE_H #define ANALYSE_H extern "C" { void analyze_numbers(int x, int y); } #endif

interoperability/rust/libanalyze/Android.bp

rust_ffi { name: "libanalyze_ffi", crate_name: "analyze_ffi", srcs: ["analyze.rs"], include_dirs: ["."], }

We can now call this from a C binary:

interoperability/rust/analyze/main.c

#include "analyze.h" int main() { analyze_numbers(10, 20); analyze_numbers(123, 123); return 0; }

interoperability/rust/analyze/Android.bp

cc_binary { name: "analyze_numbers", srcs: ["main.c"], static_libs: ["libanalyze_ffi"], }

Build, push, and run the binary on your device:

m analyze_numbers adb push "$ANDROID_PRODUCT_OUT/system/bin/analyze_numbers" /data/local/tmp adb shell /data/local/tmp/analyze_numbers

Speaker Notes

#[no_mangle] disables Rust’s usual name mangling, so the exported symbol will just be the name of the function. You can also use #[export_name = "some_name"] to specify whatever name you want.