broken db: fix assertion in leveldb::InternalKey::Encode, mark base as corrupt

db/dbformat.h

@@ -150,7 +150,11 @@ class InternalKey {
     AppendInternalKey(&rep_, ParsedInternalKey(user_key, s, t));
   }
 
-  void DecodeFrom(const Slice& s) { rep_.assign(s.data(), s.size()); }
+  bool DecodeFrom(const Slice& s) {
+    rep_.assign(s.data(), s.size());
+    return !rep_.empty();
+  }
+
   Slice Encode() const {
     assert(!rep_.empty());
     return rep_;

db/version_edit.cc

@@ -88,8 +88,7 @@ void VersionEdit::EncodeTo(std::string* dst) const {
 static bool GetInternalKey(Slice* input, InternalKey* dst) {
   Slice str;
   if (GetLengthPrefixedSlice(input, &str)) {
-    dst->DecodeFrom(str);
-    return true;
+    return dst->DecodeFrom(str);
   } else {
     return false;
   }