refactor(parse,codegen): Pass all func ops to MiddlewareChains

Previously each Event(Operation) was passed through all MiddlewareChains
one at a time. Additionally, the wasmparser library prevented cloning
the Operators which prevented more than one Operator from being observed
at a time.

This commit loads all Operators of a function into a Vec and passes the
entire Vec through the middleware chains. This design does not affect
the existing MiddlewareChains but allows chains to look back at
previously viewed Operators within the same function. This commit uses a
forked wasmparser that adds the Clone trait to wasmparser::Operator to
allow this.

Looking back at previously seen Operators is necessary for allowing the
metering MiddlewareChain to properly inject metering code so as to patch
the flaws described in Issue #999.

Cargo.toml

@@ -110,3 +110,6 @@ crate-type = ["bin"]
 [[example]]
 name = "callback"
 crate-type = ["bin"]
+
+[patch.crates-io]
+wasmparser =  { git = "https://github.com/AdamSLevy/wasmparser", branch = "OperatorClonev0.39.3" }

lib/runtime-core/Cargo.toml

@@ -12,7 +12,7 @@ edition = "2018"
 [dependencies]
 nix = "0.15"
 page_size = "0.4"
-wasmparser = "0.39.1"
+wasmparser = "0.39.3"
 parking_lot = "0.9"
 lazy_static = "1.4"
 errno = "0.2"

lib/runtime-core/src/codegen.rs

@@ -11,7 +11,6 @@ use crate::{
     structures::Map,
     types::{FuncIndex, FuncSig, SigIndex},
 };
-use smallvec::SmallVec;
 use std::any::Any;
 use std::collections::HashMap;
 use std::fmt;
@@ -274,7 +273,8 @@ fn requires_pre_validation(backend: Backend) -> bool {
 
 /// A sink for parse events.
 pub struct EventSink<'a, 'b> {
-    buffer: SmallVec<[Event<'a, 'b>; 2]>,
+    /// document this
+    pub buffer: Vec<Event<'a, 'b>>,
 }
 
 impl<'a, 'b> EventSink<'a, 'b> {
@@ -301,18 +301,14 @@ impl MiddlewareChain {
     }
 
     /// Run this chain with the provided function code generator, event and module info.
-    pub(crate) fn run<E: Debug, FCG: FunctionCodeGenerator<E>>(
+    pub(crate) fn run<'a, 'b: 'a, E: Debug, FCG: FunctionCodeGenerator<E>>(
         &mut self,
         fcg: Option<&mut FCG>,
-        ev: Event,
+        mut sink: EventSink<'a, 'b>,
         module_info: &ModuleInfo,
     ) -> Result<(), String> {
-        let mut sink = EventSink {
-            buffer: SmallVec::new(),
-        };
-        sink.push(ev);
         for m in &mut self.chain {
-            let prev: SmallVec<[Event; 2]> = sink.buffer.drain().collect();
+            let prev: Vec<Event> = sink.buffer.drain(..).collect();
             for ev in prev {
                 m.feed_event(ev, module_info, &mut sink)?;
             }

lib/runtime-core/src/parse.rs

@@ -249,8 +249,8 @@ pub fn read_module<
                         .map_err(|x| LoadError::Codegen(format!("{:?}", x)))?;
                 }
 
+                let mut events: Vec<Event> = Vec::new();
                 let mut body_begun = false;
-
                 loop {
                     let state = parser.read();
                     match state {
@@ -266,28 +266,22 @@ pub fn read_module<
                                 body_begun = true;
                                 fcg.begin_body(&info.read().unwrap())
                                     .map_err(|x| LoadError::Codegen(format!("{:?}", x)))?;
-                                middlewares
-                                    .run(
-                                        Some(fcg),
-                                        Event::Internal(InternalEvent::FunctionBegin(id as u32)),
-                                        &info.read().unwrap(),
-                                    )
-                                    .map_err(|x| LoadError::Codegen(x))?;
+                                events
+                                    .push(Event::Internal(InternalEvent::FunctionBegin(id as u32)));
                             }
-                            middlewares
-                                .run(Some(fcg), Event::Wasm(op), &info.read().unwrap())
-                                .map_err(|x| LoadError::Codegen(x))?;
+                            events.push(Event::WasmOwned(op.clone()));
+                        }
+                        ParserState::EndFunctionBody => {
+                            events.push(Event::Internal(InternalEvent::FunctionEnd));
+                            break;
                         }
-                        ParserState::EndFunctionBody => break,
                         _ => unreachable!(),
                     }
                 }
+
+                let events = EventSink { buffer: events };
                 middlewares
-                    .run(
-                        Some(fcg),
-                        Event::Internal(InternalEvent::FunctionEnd),
-                        &info.read().unwrap(),
-                    )
+                    .run(Some(fcg), events, &info.read().unwrap())
                     .map_err(|x| LoadError::Codegen(x))?;
                 fcg.finalize()
                     .map_err(|x| LoadError::Codegen(format!("{:?}", x)))?;