WebAssembly: skip unknown sections, add names

src/wasm/decoder.h

 // 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.
 
 #ifndef V8_WASM_DECODER_H_
 #define V8_WASM_DECODER_H_
 
 #include "src/base/smart-pointers.h"
 #include "src/flags.h"
 #include "src/signature.h"
@@ skipping 213 matching lines @@
       if (pc_ == end && (b & 0x80)) {
         error(pc_ - 1, "varint too large");
       } else {
         TRACE("= %u\n", result);
       }
       return result;
     }
     return traceOffEnd<uint32_t>();
   }
 
+  // Consume {size} bytes and send them to the bit bucket, advancing {pc_}.
+  void consume_bytes(int size) {
+    if (checkAvailable(size)) {
+      pc_ += size;
+    } else {
+      pc_ = limit_;
+    }
+  }
+
   // Check that at least {size} bytes exist between {pc_} and {limit_}.
   bool checkAvailable(int size) {
-    if (pc_ < start_ || (pc_ + size) > limit_) {
+    intptr_t pc_overflow_value = std::numeric_limits<intptr_t>::max() - size;
+    if (size < 0 || (intptr_t)pc_ > pc_overflow_value) {
+      error(pc_, nullptr, "reading %d bytes would underflow/overflow", size);
+      return false;
+    } else if (pc_ < start_ || limit_ < (pc_ + size)) {
       error(pc_, nullptr, "expected %d bytes, fell off end", size);
       return false;
     } else {
       return true;
     }
   }
 
   void error(const char* msg) { error(pc_, nullptr, msg); }
 
   void error(const byte* pc, const char* msg) { error(pc, nullptr, msg); }
@@ skipping 119 matching lines @@
     return result;
   }
 };
 
 #undef TRACE
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_WASM_DECODER_H_