| import errno |
| import os |
| import select |
| import struct |
| |
| import six |
| |
| try: |
| from ..transport import NpipeSocket |
| except ImportError: |
| NpipeSocket = type(None) |
| |
| |
| class SocketError(Exception): |
| pass |
| |
| |
| def read(socket, n=4096): |
| """ |
| Reads at most n bytes from socket |
| """ |
| |
| recoverable_errors = (errno.EINTR, errno.EDEADLK, errno.EWOULDBLOCK) |
| |
| # wait for data to become available |
| if not isinstance(socket, NpipeSocket): |
| select.select([socket], [], []) |
| |
| try: |
| if hasattr(socket, 'recv'): |
| return socket.recv(n) |
| return os.read(socket.fileno(), n) |
| except EnvironmentError as e: |
| if e.errno not in recoverable_errors: |
| raise |
| |
| |
| def read_exactly(socket, n): |
| """ |
| Reads exactly n bytes from socket |
| Raises SocketError if there isn't enough data |
| """ |
| data = six.binary_type() |
| while len(data) < n: |
| next_data = read(socket, n - len(data)) |
| if not next_data: |
| raise SocketError("Unexpected EOF") |
| data += next_data |
| return data |
| |
| |
| def next_frame_size(socket): |
| """ |
| Returns the size of the next frame of data waiting to be read from socket, |
| according to the protocol defined here: |
| |
| https://docs.docker.com/engine/reference/api/docker_remote_api_v1.24/#/attach-to-a-container |
| """ |
| try: |
| data = read_exactly(socket, 8) |
| except SocketError: |
| return 0 |
| |
| _, actual = struct.unpack('>BxxxL', data) |
| return actual |
| |
| |
| def frames_iter(socket): |
| """ |
| Returns a generator of frames read from socket |
| """ |
| n = next_frame_size(socket) |
| while n > 0: |
| yield read(socket, n) |
| n = next_frame_size(socket) |
