From f09149f4f7fee8fb956afeed6b8d9dfb68ab7073 Mon Sep 17 00:00:00 2001
From: Andrey Voronkov <voronkovaa@gmail.com>
Date: Fri, 16 Aug 2019 22:06:19 +0200
Subject: [PATCH] Add rust to go dynamic library example.

---
 rust-to-go-dynamic/Cargo.toml    | 10 ++++++++++
 rust-to-go-dynamic/build.rs      | 13 +++++++++++++
 rust-to-go-dynamic/src/double.go | 10 ++++++++++
 rust-to-go-dynamic/src/main.rs   | 12 ++++++++++++
 4 files changed, 45 insertions(+)
 create mode 100644 rust-to-go-dynamic/Cargo.toml
 create mode 100644 rust-to-go-dynamic/build.rs
 create mode 100644 rust-to-go-dynamic/src/double.go
 create mode 100644 rust-to-go-dynamic/src/main.rs

diff --git a/rust-to-go-dynamic/Cargo.toml b/rust-to-go-dynamic/Cargo.toml
new file mode 100644
index 0000000..3e98c02
--- /dev/null
+++ b/rust-to-go-dynamic/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "rust-to-go"
+version = "0.1.0"
+authors = ["Andrey Voronkov <voronkovaa@gmail.com>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+libc = "0.2"
diff --git a/rust-to-go-dynamic/build.rs b/rust-to-go-dynamic/build.rs
new file mode 100644
index 0000000..03936ef
--- /dev/null
+++ b/rust-to-go-dynamic/build.rs
@@ -0,0 +1,13 @@
+use std::process::Command;
+
+fn main() {
+    println!(r"cargo:rustc-link-search=target/debug");
+    let os = Command::new("uname")
+        .output().unwrap();
+    let ext = match String::from_utf8_lossy(os.stdout.as_slice()).into_owned().trim_end().as_ref() {
+        "Darwin" => "dylib",
+        _ => "so"
+    };
+    Command::new("go").args(&["build", "-o", &format!("target/debug/libdouble_input.{}", ext), "-buildmode=c-shared", "src/double.go"])
+        .status().unwrap();
+}
diff --git a/rust-to-go-dynamic/src/double.go b/rust-to-go-dynamic/src/double.go
new file mode 100644
index 0000000..f877928
--- /dev/null
+++ b/rust-to-go-dynamic/src/double.go
@@ -0,0 +1,10 @@
+package main
+
+import "C"
+
+//export DoubleInput
+func DoubleInput(input int32) int32 {
+  return input * 2
+}
+
+func main() {}
diff --git a/rust-to-go-dynamic/src/main.rs b/rust-to-go-dynamic/src/main.rs
new file mode 100644
index 0000000..99fb7d8
--- /dev/null
+++ b/rust-to-go-dynamic/src/main.rs
@@ -0,0 +1,12 @@
+extern crate libc;
+
+#[link(name = "double_input")]
+extern {
+    fn DoubleInput(input: libc::c_int) -> libc::c_int;
+}
+
+fn main() {
+    let input = 2;
+    let output = unsafe { DoubleInput(input) };
+    println!("{} * 2 = {}", input, output);
+}