Function doRead

src/gridfs/download.ts:217–303

(stream: GridFSBucketReadStream)

}

function doRead(stream: GridFSBucketReadStream): void {
  if (stream.destroyed) return;
  if (!stream.s.cursor) return;
  if (!stream.s.file) return;

  const handleReadResult = (doc: Document | null) => {
    if (stream.destroyed) return;

    if (!doc) {
      stream.push(null);

      stream.s.cursor?.close().then(undefined, error => stream.destroy(error));
      return;
    }

    if (!stream.s.file) return;

    const bytesRemaining = stream.s.file.length - stream.s.bytesRead;
    const expectedN = stream.s.expected++;
    const expectedLength = Math.min(stream.s.file.chunkSize, bytesRemaining);
    if (doc.n > expectedN) {
      return stream.destroy(
        new MongoGridFSChunkError(
          `ChunkIsMissing: Got unexpected n: ${doc.n}, expected: ${expectedN}`
        )
      );
    }

    if (doc.n < expectedN) {
      return stream.destroy(
        new MongoGridFSChunkError(`ExtraChunk: Got unexpected n: ${doc.n}, expected: ${expectedN}`)
      );
    }

    let buf = ByteUtils.isUint8Array(doc.data) ? doc.data : doc.data.buffer;

    if (buf.byteLength !== expectedLength) {
      if (bytesRemaining <= 0) {
        return stream.destroy(
          new MongoGridFSChunkError(
            `ExtraChunk: Got unexpected n: ${doc.n}, expected file length ${stream.s.file.length} bytes but already read ${stream.s.bytesRead} bytes`
          )
        );
      }

      return stream.destroy(
        new MongoGridFSChunkError(
          `ChunkIsWrongSize: Got unexpected length: ${buf.byteLength}, expected: ${expectedLength}`
        )
      );
    }

    stream.s.bytesRead += buf.byteLength;

    if (buf.byteLength === 0) {
      return stream.push(null);
    }