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crates/runner/plugin/cargo_test/src/main.rs

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+use core::slice;
+
+#[repr(C)]
+pub struct Buffer {
+    ptr: *const u8,
+    len: usize,
+}
+
+/// Allocates a buffer with an exact size.
+/// We don't return the size because it has to be passed in anyway.
+#[no_mangle]
+pub extern "C" fn __alloc_buffer(len: usize) -> *const u8 {
+    let vec = vec![0; len];
+    let buffer = unsafe { Buffer::from_vec(vec) };
+    return buffer.ptr;
+}
+
+/// Frees a given buffer, requires the size.
+#[no_mangle]
+pub extern "C" fn __free_buffer(ptr: *const u8, len: usize) {
+    let buffer = Buffer { ptr, len };
+    let vec = unsafe { buffer.to_vec() };
+    std::mem::drop(vec);
+}
+
+impl Buffer {
+    pub unsafe fn to_vec(&self) -> Vec<u8> {
+        slice::from_raw_parts(self.ptr, self.len).to_vec()
+    }
+
+    pub unsafe fn from_vec(mut vec: Vec<u8>) -> Buffer {
+        vec.shrink_to(0);
+        let ptr = vec.as_ptr();
+        let len = vec.len();
+        std::mem::forget(vec);
+        Buffer { ptr, len }
+    }
+
+    pub fn leak_to_heap(self) -> *const Buffer {
+        let boxed = Box::new(self);
+        let ptr = Box::<Buffer>::into_raw(boxed) as *const Buffer;
+        return ptr;
+    }
+}
+
+#[no_mangle]
+pub extern "C" fn banana(ptr: *const u8, len: usize) -> *const Buffer {
+    // setup
+    let buffer = Buffer { ptr, len };
+    let data = unsafe { buffer.to_vec() };
+    // operation
+    // let reversed: Vec<u8> = data.into_iter().rev().collect();
+    let number: f64 = bincode::deserialize(&data).unwrap();
+    let new_number = number * 2.0;
+    let new_data = bincode::serialize(&new_number).unwrap();
+    // teardown
+    let new_buffer = unsafe { Buffer::from_vec(new_data) };
+    return new_buffer.leak_to_heap();
+}
+
+pub fn main() -> () {
+    ()
+}