Expose version() in C API

ffi/src/lib.rs

@@ -1,6 +1,7 @@
 mod initialization;
 mod log;
 mod post_impl;
+mod version;
 
 #[repr(C)]
 #[derive(Debug, Clone, Copy)]

ffi/src/version.rs

@@ -0,0 +1,17 @@
+use std::ffi::{c_char, CStr};
+
+const VERSION: &str = concat!(env!("CARGO_PKG_VERSION"), "\0");
+
+#[no_mangle]
+pub extern "C" fn version() -> *const c_char {
+    unsafe { CStr::from_bytes_with_nul_unchecked(VERSION.as_bytes()) }.as_ptr()
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_version() {
+        let version = unsafe { std::ffi::CStr::from_ptr(super::version()) };
+        assert_eq!(version.to_str().unwrap(), env!("CARGO_PKG_VERSION"));
+    }
+}