调用 Rust

将 Rust 函数和类型导出到 C 很简单：

interoperability/rust/libanalyze/analyze.rs

  1. //! Rust FFI demo.
  2. #![deny(improper_ctypes_definitions)]
  4. use std::os::raw::c_int;
  6. /// Analyze the numbers.
  7. #[no_mangle]
  8. pub extern "C" fn analyze_numbers(x: c_int, y: c_int) {
  9.     if x < y {
  10.         println!("x ({x}) is smallest!");
  11.     } else {
  12.         println!("y ({y}) is probably larger than x ({x})");
  13.     }
  14. }

interoperability/rust/libanalyze/analyze.h

  1. #ifndef ANALYSE_H
  2. #define ANALYSE_H
  4. extern "C" {
  5. void analyze_numbers(int x, int y);
  6. }
  8. #endif

interoperability/rust/libanalyze/Android.bp

  1. rust_ffi {
  2.     name: "libanalyze_ffi",
  3.     crate_name: "analyze_ffi",
  4.     srcs: ["analyze.rs"],
  5.     include_dirs: ["."],
  6. }

我们现在可以从一个 C 二进制文件中调用它：

interoperability/rust/analyze/main.c

  1. #include "analyze.h"
  3. int main() {
  4.   analyze_numbers(10, 20);
  5.   analyze_numbers(123, 123);
  6.   return 0;
  7. }

interoperability/rust/analyze/Android.bp

  1. cc_binary {
  2.     name: "analyze_numbers",
  3.     srcs: ["main.c"],
  4.     static_libs: ["libanalyze_ffi"],
  5. }

在你的设备上构建，推送，并运行二进制文件 ：

  1. m analyze_numbers
  2. adb push "$ANDROID_PRODUCT_OUT/system/bin/analyze_numbers" /data/local/tmp
  3. adb shell /data/local/tmp/analyze_numbers

#[no_mangle] 禁用了 Rust 通常的名称重整，因此导出的符号将仅为函数的名称。你还可以使用 #[export_name = "some_name"] 来指定任意你想要的名称。