feat(core): implement failing stub trampoline and host dlsym resolver

crates/molotov-core/src/lib.rs

@@ -4,3 +4,4 @@ pub mod elf;
 pub mod mmap;
 pub mod reloc;
 pub mod symbols;
+pub mod trampoline;

crates/molotov-core/src/trampoline.rs

@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+use std::ffi::CString;
+
+pub extern "C" fn generic_failing_stub() -> i32 {
+    // ENOSYS is errno 38 on Linux x86_64
+    -38
+}
+
+pub fn resolve_symbol_address(symbol: &str) -> Result<u64, String> {
+    // 1. Host lookup via dlsym
+    let c_name = CString::new(symbol).map_err(|e| e.to_string())?;
+    let host_ptr = unsafe { libc::dlsym(libc::RTLD_DEFAULT, c_name.as_ptr()) };
+
+    if !host_ptr.is_null() {
+        Ok(host_ptr as u64)
+    } else {
+        // 2. Return explicit failure stub trampoline (never fake 0)
+        tracing::warn!("Resolving unimplemented symbol '{}' to generic_failing_stub (-ENOSYS)", symbol);
+        Ok(generic_failing_stub as *const () as u64)
+    }
+}

crates/molotov-core/tests/trampoline_test.rs

@@ -0,0 +1,17 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+use molotov_core::trampoline::resolve_symbol_address;
+
+#[test]
+fn test_resolve_standard_host_symbol() {
+    let addr = resolve_symbol_address("malloc").expect("malloc should resolve to host glibc");
+    assert_ne!(addr, 0);
+}
+
+#[test]
+fn test_unimplemented_stub_returns_failing_function() {
+    let stub_fn = resolve_symbol_address("unimplemented_android_telemetry")
+        .expect("Should resolve to a failing stub trampoline");
+    let func: extern "C" fn() -> i32 = unsafe { std::mem::transmute(stub_fn) };
+    let ret = func();
+    assert_eq!(ret, -38, "Stub must return -ENOSYS (-38), never fake 0 or success");
+}