Deserialisation fails for nested Maps and Sets

While both serialisation and deserialisation workds fine if Maps and Sets are only used on top level, the deserialisation throws when they are nested in other objects.

const { desia, sia, DeSia, Sia } = require('sializer');

let obj = new Map();
let buf = sia(obj);
obj = desia(buf); //fine

obj = { k: new Map() };
buf = sia(obj);
obj = desia(buf); //throws string "Key of type 57 is invalid."

This bug is apparently already fixed in the fork by @c7x43t, but that fork does not yet have TypeScript support.

As far as I can tell, the Problem is simply that this.offset in the Deserialiser is not incremented at the end of

      case SIA_TYPES.mapStart: {
        const map = new Map();
        let curr = this.buffer[this.offset];
        while (curr !== SIA_TYPES.mapEnd) {
          map.set(this.readBlock(), this.readBlock());
          curr = this.buffer[this.offset];
        }
        //insert increment here
        return map;
      }

to skip over the SIA_TYPES.mapEnd byte, which is not incremented over before, because it might be the start of the next block. So adding this.offset++; before the return fixes it.

I tried this fix locally for both Map and Set and confirmed that deserialisation works as expected then.

pouya-eghbali / sia

Deserialisation fails for nested Maps and Sets #12