Added function test

Author: Reim-developer

rustlib_test/src/lib.rs

@@ -0,0 +1,26 @@
+#![deny(clippy::all, clippy::pedantic, clippy::nursery, clippy::perf)]
+
+use std::{ffi::CString, os::raw::c_char};
+use std::ptr::null_mut;
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn greet() {
+    println!("Hello World");
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn get_reim_name() -> *mut c_char {
+    CString
+        ::new("REIM DEVELOPER")
+        .map(|name| name.into_raw())
+        .unwrap_or(null_mut())
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn free_name(c_string: *mut c_char) {
+    if !c_string.is_null() {
+        unsafe  {
+            let _ = CString::from_raw(c_string);
+        }
+    }
+}