docs(exec_enclave): add docs to sample function unsafe code

Co-authored-by: Pi Delport <[email protected]>

rtc_exec_enclave/src/lib.rs

@@ -31,6 +31,9 @@ pub fn request_execution(token: Token, _params: ()) -> Result<Box<[u8]>, ()> {
     let data = get_data(&token);
 
     // as_ptr() does not take ownership, so the data will be dropped at the end of this function
+    // Safety:
+    // As long as `data` is valid, this should be safe.
+    // Memory will be cleaned up when `data` goes out of scope, which will be after the unsafe function call.
     let result = unsafe { exec_module.call(data.as_ptr(), data.len()) };
 
     match result {

rtc_exec_enclave/src/types.rs

@@ -5,5 +5,9 @@ pub(crate) type CallReturnValue = Box<[u8]>;
 pub(crate) type ExecResult = core::result::Result<CallReturnValue, ()>;
 
 pub(crate) trait ExecModule {
+    /// Calls the entry function of a module with the provided dataset and return the result
+    ///
+    /// # Safety
+    /// The caller must ensure that `dataset_ptr` is a valid pointer to a `u8` slice of `dataset_len`
     unsafe fn call(&self, dataset_ptr: *const u8, dataset_len: usize) -> ExecResult;
 }