readCString method

String readCString(int ptr)

Decodes a NUL-terminated C string at ptr (chunked scan — avoids a JS call per byte). Preserves a leading BOM, tolerates malformed UTF-8.

Implementation

String readCString(int ptr) {
  if (ptr == 0) return '';
  const chunk = 64;
  final collected = BytesBuilder(copy: false);
  var base = ptr;
  while (true) {
    final bytes = readBytes(base, chunk);
    // Past the end of linear memory, `slice` returns fewer bytes than asked
    // for — and nothing at all at/after the end. Treating that as "no NUL
    // yet" spun forever; an unterminated string is a bug in the producer,
    // so surface it instead of burning CPU.
    if (bytes.isEmpty) {
      throw StateError(
        'readCString: unterminated C string at $ptr — scanned to the end of '
        'linear memory (${base - ptr} bytes) without a NUL terminator.',
      );
    }
    final nul = bytes.indexOf(0);
    if (nul >= 0) {
      collected.add(Uint8List.sublistView(bytes, 0, nul));
      break;
    }
    collected.add(bytes);
    base += bytes.length;
  }
  return decodeUtf8NoBomStrip(collected.takeBytes());
}