runtime: Add abort shim for Fortanix SGX

runtime/src/abort.rs

@@ -0,0 +1,25 @@
+//! Abort shim for the Fortanix SGX target.
+//!
+//! Why this exists:
+//!
+//! Some native libraries assume the standard C function `abort()` is
+//! available. In our case, the `wasm3` runtime (via `wasm3-sys`) calls
+//! `abort()` from C code (`m3_core.c` -> `m3_Abort`).
+//!
+//! When linking for `x86_64-fortanix-unknown-sgx`, there is no libc
+//! providing the `abort` symbol, so linking fails with:
+//!
+//!     rust-lld: error: undefined symbol: abort
+//!
+//! This shim exports a C-compatible symbol named `abort` and forwards
+//! execution to Rust's internal abort routine (`__rust_abort`), which
+//! terminates the enclave/process immediately and never returns.
+
+#[no_mangle]
+pub extern "C" fn abort() -> ! {
+    extern "C" {
+        fn __rust_abort() -> !;
+    }
+
+    unsafe { __rust_abort() }
+}

runtime/src/main.rs

@@ -1,5 +1,8 @@
 use oasis_runtime_sdk::Runtime;
 
+#[cfg(all(target_env = "sgx", target_vendor = "fortanix"))]
+mod abort;
+
 fn main() {
     cipher_paratime::Runtime::start();
 }