Current File : //proc/self/root/lib/python3.6/site-packages/dockerpty/io.py
# dockerpty: io.py
#
# Copyright 2014 Chris Corbyn <chris@w3style.co.uk>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import os
import fcntl
import errno
import struct
import select as builtin_select
import six
def set_blocking(fd, blocking=True):
"""
Set the given file-descriptor blocking or non-blocking.
Returns the original blocking status.
"""
old_flag = fcntl.fcntl(fd, fcntl.F_GETFL)
if blocking:
new_flag = old_flag & ~ os.O_NONBLOCK
else:
new_flag = old_flag | os.O_NONBLOCK
fcntl.fcntl(fd, fcntl.F_SETFL, new_flag)
return not bool(old_flag & os.O_NONBLOCK)
def select(read_streams, write_streams, timeout=0):
"""
Select the streams from `read_streams` that are ready for reading, and
streams from `write_streams` ready for writing.
Uses `select.select()` internally but only returns two lists of ready streams.
"""
exception_streams = []
try:
return builtin_select.select(
read_streams,
write_streams,
exception_streams,
timeout,
)[0:2]
except builtin_select.error as e:
# POSIX signals interrupt select()
no = e.errno if six.PY3 else e[0]
if no == errno.EINTR:
return ([], [])
else:
raise e
class Stream(object):
"""
Generic Stream class.
This is a file-like abstraction on top of os.read() and os.write(), which
add consistency to the reading of sockets and files alike.
"""
"""
Recoverable IO/OS Errors.
"""
ERRNO_RECOVERABLE = [
errno.EINTR,
errno.EDEADLK,
errno.EWOULDBLOCK,
]
def __init__(self, fd):
"""
Initialize the Stream for the file descriptor `fd`.
The `fd` object must have a `fileno()` method.
"""
self.fd = fd
self.buffer = b''
self.close_requested = False
self.closed = False
def fileno(self):
"""
Return the fileno() of the file descriptor.
"""
return self.fd.fileno()
def set_blocking(self, value):
if hasattr(self.fd, 'setblocking'):
self.fd.setblocking(value)
return True
else:
return set_blocking(self.fd, value)
def read(self, n=4096):
"""
Return `n` bytes of data from the Stream, or None at end of stream.
"""
while True:
try:
if hasattr(self.fd, 'recv'):
return self.fd.recv(n)
return os.read(self.fd.fileno(), n)
except EnvironmentError as e:
if e.errno not in Stream.ERRNO_RECOVERABLE:
raise e
def write(self, data):
"""
Write `data` to the Stream. Not all data may be written right away.
Use select to find when the stream is writeable, and call do_write()
to flush the internal buffer.
"""
if not data:
return None
self.buffer += data
self.do_write()
return len(data)
def do_write(self):
"""
Flushes as much pending data from the internal write buffer as possible.
"""
while True:
try:
written = 0
if hasattr(self.fd, 'send'):
written = self.fd.send(self.buffer)
else:
written = os.write(self.fd.fileno(), self.buffer)
self.buffer = self.buffer[written:]
# try to close after writes if a close was requested
if self.close_requested and len(self.buffer) == 0:
self.close()
return written
except EnvironmentError as e:
if e.errno not in Stream.ERRNO_RECOVERABLE:
raise e
def needs_write(self):
"""
Returns True if the stream has data waiting to be written.
"""
return len(self.buffer) > 0
def close(self):
self.close_requested = True
# We don't close the fd immediately, as there may still be data pending
# to write.
if not self.closed and len(self.buffer) == 0:
self.closed = True
if hasattr(self.fd, 'close'):
self.fd.close()
else:
os.close(self.fd.fileno())
def __repr__(self):
return "{cls}({fd})".format(cls=type(self).__name__, fd=self.fd)
class Demuxer(object):
"""
Wraps a multiplexed Stream to read in data demultiplexed.
Docker multiplexes streams together when there is no PTY attached, by
sending an 8-byte header, followed by a chunk of data.
The first 4 bytes of the header denote the stream from which the data came
(i.e. 0x01 = stdout, 0x02 = stderr). Only the first byte of these initial 4
bytes is used.
The next 4 bytes indicate the length of the following chunk of data as an
integer in big endian format. This much data must be consumed before the
next 8-byte header is read.
"""
def __init__(self, stream):
"""
Initialize a new Demuxer reading from `stream`.
"""
self.stream = stream
self.remain = 0
def fileno(self):
"""
Returns the fileno() of the underlying Stream.
This is useful for select() to work.
"""
return self.stream.fileno()
def set_blocking(self, value):
return self.stream.set_blocking(value)
def read(self, n=4096):
"""
Read up to `n` bytes of data from the Stream, after demuxing.
Less than `n` bytes of data may be returned depending on the available
payload, but the number of bytes returned will never exceed `n`.
Because demuxing involves scanning 8-byte headers, the actual amount of
data read from the underlying stream may be greater than `n`.
"""
size = self._next_packet_size(n)
if size <= 0:
return
else:
data = six.binary_type()
while len(data) < size:
nxt = self.stream.read(size - len(data))
if not nxt:
# the stream has closed, return what data we got
return data
data = data + nxt
return data
def write(self, data):
"""
Delegates the the underlying Stream.
"""
return self.stream.write(data)
def needs_write(self):
"""
Delegates to underlying Stream.
"""
if hasattr(self.stream, 'needs_write'):
return self.stream.needs_write()
return False
def do_write(self):
"""
Delegates to underlying Stream.
"""
if hasattr(self.stream, 'do_write'):
return self.stream.do_write()
return False
def close(self):
"""
Delegates to underlying Stream.
"""
return self.stream.close()
def _next_packet_size(self, n=0):
size = 0
if self.remain > 0:
size = min(n, self.remain)
self.remain -= size
else:
data = six.binary_type()
while len(data) < 8:
nxt = self.stream.read(8 - len(data))
if not nxt:
# The stream has closed, there's nothing more to read
return 0
data = data + nxt
if data is None:
return 0
if len(data) == 8:
__, actual = struct.unpack('>BxxxL', data)
size = min(n, actual)
self.remain = actual - size
return size
def __repr__(self):
return "{cls}({stream})".format(cls=type(self).__name__,
stream=self.stream)
class Pump(object):
"""
Stream pump class.
A Pump wraps two Streams, reading from one and and writing its data into
the other, much like a pipe but manually managed.
This abstraction is used to facilitate piping data between the file
descriptors associated with the tty and those associated with a container's
allocated pty.
Pumps are selectable based on the 'read' end of the pipe.
"""
def __init__(self,
from_stream,
to_stream,
wait_for_output=True,
propagate_close=True):
"""
Initialize a Pump with a Stream to read from and another to write to.
`wait_for_output` is a flag that says that we need to wait for EOF
on the from_stream in order to consider this pump as "done".
"""
self.from_stream = from_stream
self.to_stream = to_stream
self.eof = False
self.wait_for_output = wait_for_output
self.propagate_close = propagate_close
def fileno(self):
"""
Returns the `fileno()` of the reader end of the Pump.
This is useful to allow Pumps to function with `select()`.
"""
return self.from_stream.fileno()
def set_blocking(self, value):
return self.from_stream.set_blocking(value)
def flush(self, n=4096):
"""
Flush `n` bytes of data from the reader Stream to the writer Stream.
Returns the number of bytes that were actually flushed. A return value
of zero is not an error.
If EOF has been reached, `None` is returned.
"""
try:
read = self.from_stream.read(n)
if read is None or len(read) == 0:
self.eof = True
if self.propagate_close:
self.to_stream.close()
return None
return self.to_stream.write(read)
except OSError as e:
if e.errno != errno.EPIPE:
raise e
def is_done(self):
"""
Returns True if the read stream is done (either it's returned EOF or
the pump doesn't have wait_for_output set), and the write
side does not have pending bytes to send.
"""
return (not self.wait_for_output or self.eof) and \
not (hasattr(self.to_stream, 'needs_write') and self.to_stream.needs_write())
def __repr__(self):
return "{cls}(from={from_stream}, to={to_stream})".format(
cls=type(self).__name__,
from_stream=self.from_stream,
to_stream=self.to_stream)
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