Parsing fixes (#990)

* properly catch a bunch of possible parse errors, found by afl-fuzz

* clean up wasm-interpreter, use WASM_UNREACHABLE instead of abort

* detect duplicate names in function names section

* detect duplicate export names

1 files changed, 4 insertions, 2 deletions

diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index 0263b2112..2290a4972 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -48,7 +48,7 @@ Element::List& Element::list() {
 }
 
 Element* Element::operator[](unsigned i) {
-  if (i >= list().size()) element_assert(0 && "expected more elements in list");
+  if (i >= list().size()) throw ParseException("expected more elements in list", line, col);
   return list()[i];
 }
 
@@ -114,8 +114,10 @@ Element* SExpressionParser::parse() {
     } else if (input[0] == ')') {
       input++;
       auto last = curr;
+      if (stack.empty()) {
+        throw ParseException("s-expr stack empty");
+      }
       curr = stack.back();
-      assert(stack.size());
       stack.pop_back();
       curr->list().push_back(last);
     } else {