[wasm] Verify boundaries of data segments when decoding modules.

src/wasm/wasm-opcodes.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/wasm/wasm-opcodes.h"
 #include "src/signature.h"
 
 namespace v8 {
 namespace internal {
 namespace wasm {
 
 typedef Signature<LocalType> FunctionSig;
 
 const char* WasmOpcodes::OpcodeName(WasmOpcode opcode) {
   switch (opcode) {
 #define DECLARE_NAME_CASE(name, opcode, sig) \
   case kExpr##name:                          \
     return "Expr" #name;
     FOREACH_OPCODE(DECLARE_NAME_CASE)
 #undef DECLARE_NAME_CASE
     default:
       break;
   }
   return "Unknown";
 }
 
 
+std::ostream& operator<<(std::ostream& os, const FunctionSig& sig) {
+  if (sig.return_count() == 0) os << "v";
+  for (size_t i = 0; i < sig.return_count(); i++) {
+    os << WasmOpcodes::ShortNameOf(sig.GetReturn(i));
+  }
+  os << "_";
+  if (sig.parameter_count() == 0) os << "v";
+  for (size_t i = 0; i < sig.parameter_count(); i++) {
+    os << WasmOpcodes::ShortNameOf(sig.GetParam(i));
+  }
+  return os;
+}
+
+
 #define DECLARE_SIG_ENUM(name, ...) kSigEnum_##name,
 
 
 enum WasmOpcodeSig { FOREACH_SIGNATURE(DECLARE_SIG_ENUM) };
 
 
 // TODO(titzer): not static-initializer safe. Wrap in LazyInstance.
 #define DECLARE_SIG(name, ...)                      \
   static LocalType kTypes_##name[] = {__VA_ARGS__}; \
   static const FunctionSig kSig_##name(             \
@@ skipping 86 matching lines @@
     default:
       return true;
   }
 #else
   return true;
 #endif
 }
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8