doc for certain write

Author: nia-e

src/shims/native_lib/trace/parent.rs

@@ -389,7 +389,13 @@ fn capstone_find_events(
                         // FIXME: This could be made certain; either determine all cases where
                         // only reads happen, or have an intermediate mempr_* function to first
                         // map the page(s) as readonly and check if a segfault occurred.
-                        // If this did a read as well, it's possible the write didn't happen.
+                        
+                        // Per https://docs.rs/iced-x86/latest/iced_x86/enum.OpAccess.html,
+                        // we know that the possible access types are Read, CondRead, Write,
+                        // CondWrite, ReadWrite, and ReadCondWrite. Since we got a segfault
+                        // we know some kind of access happened so Cond{Read, Write}s are
+                        // certain reads and writes; the only uncertaintly is with an RW op
+                        // as it might be a ReadCondWrite with the write condition unmet.
                         acc_events.push(AccessEvent::Write(push, !acc_ty.is_readable()));
                     }