feat(ffi): Initial C API for hyper

src/ffi/macros.rs

@@ -0,0 +1,23 @@
+macro_rules! ffi_fn {
+    ($(#[$doc:meta])* fn $name:ident($($arg:ident: $arg_ty:ty),*) -> $ret:ty $body:block) => {
+        $(#[$doc])*
+        #[no_mangle]
+        pub extern fn $name($($arg: $arg_ty),*) -> $ret {
+            use std::panic::{self, AssertUnwindSafe};
+
+            match panic::catch_unwind(AssertUnwindSafe(move || $body)) {
+                Ok(v) => v,
+                Err(_) => {
+                    // TODO: We shouldn't abort, but rather figure out how to
+                    // convert into the return type that the function errored.
+                    eprintln!("panic unwind caught, aborting");
+                    std::process::abort();
+                }
+            }
+        }
+    };
+
+    ($(#[$doc:meta])* fn $name:ident($($arg:ident: $arg_ty:ty),*) $body:block) => {
+        ffi_fn!($(#[$doc])* fn $name($($arg: $arg_ty),*) -> () $body);
+    };
+}