* `write(data)`: Writes `data` (`str` or `bytes`) to the file.
* `read(size)`: Reads `size` (`int`) bytes/characters of the file.
* `seek(offset)`: Goes to the byte position `offset` (`int`) in the file.
    * E.g., `await myfile.seek(0)` would go to the start of the file.
    * This is especially useful if you run `await myfile.read()` once and then need to read the contents again.
* `close()`: Closes the file.

    /**
     * Attaches [tag] to the request using [T] as a key. Tags can be read from a request using
     * [Request.tag]. Use null to remove any existing tag assigned for [T].
     *
     * Use this API to attach timing, debugging, or other application data to a request so that
     * you may read it in interceptors, event listeners, or callbacks.
     */
    @JvmName("reifiedTag")

    /** The next byte to read. This is always less than or equal to [upstreamPos]. */
    private var sourcePos = 0L

    /**
     * Selects where to find the bytes for a read and read them. This is one of three sources.
     *
     * ## Upstream
     *
     * In this case the current thread is assigned as the upstream reader. We read bytes from

    @Throws(IOException::class)
    override fun read(
      sink: Buffer,
      byteCount: Long,
    ): Long {
      while (left == 0) {
        source.skip(padding.toLong())
        padding = 0
        if (flags and FLAG_END_HEADERS != 0) return -1L
        readContinuationHeader()
        // TODO: test case for empty continuation header?
      }

      val read = source.read(sink, minOf(byteCount, left.toLong()))

  private val countingSource: CountingSource = CountingSource(source)
  private val source: BufferedSource = countingSource.buffer()

  /** Total bytes read thus far. */
  private val byteCount: Long
    get() = countingSource.bytesRead - source.buffer.size

  /** How many bytes to read before [peekHeader] should return false, or -1L for no limit. */
  private var limit = -1L

 *
 * Unfortunately Java's networking APIs don't offer a good health check, so we go on our own by
 * attempting to read with a short timeout. If the fails immediately we know the socket is
 * unhealthy.
 *
 * @param source the source used to read bytes from the socket.
 */
internal fun Socket.isHealthy(source: BufferedSource): Boolean {
  return try {
    val readTimeout = soTimeout
    try {

 * class to read a response that is larger than the entire memory allocated to the current process.
 * It can even stream a response larger than the total storage on the current device, which is a
 * common requirement for video streaming applications.
 *
 * Because this class does not buffer the full response in memory, the application may not

        }

        // Fill the receive buffer without holding any locks.
        val read = source.read(receiveBuffer, remainingByteCount)
        if (read == -1L) throw EOFException()
        remainingByteCount -= read

        // Move the received data to the read buffer to the reader can read it. If this source has
        // been closed since this read began we must discard the incoming data and tell the
        // connection we've done so.

      }

      val read = super.read(sink, minOf(byteCount, bytesRemainingInChunk))
      if (read == -1L) {
        carrier.noNewExchanges() // The server didn't supply the promised chunk length.
        val e = ProtocolException("unexpected end of stream")
        responseBodyComplete()
        throw e
      }
      bytesRemainingInChunk -= read
      return read
    }

    val body = body("")
    val bytes = body.byteStream()
    assertThat(bytes.read()).isEqualTo(-1)
  }

  @Test
  fun byteStreamSeesBom() {
    val body = body("efbbbf68656c6c6f")
    val bytes = body.byteStream()
    assertThat(bytes.read()).isEqualTo(0xef)
    assertThat(bytes.read()).isEqualTo(0xbb)
    assertThat(bytes.read()).isEqualTo(0xbf)