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#
# Copyright (c) 2012 Canonical
#
# This file is part of Checkbox.
#
# Storm is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as
# published by the Free Software Foundation; either version 2.1 of
# the License, or (at your option) any later version.
#
# Storm is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
__metaclass__ = type
__all__ = [
"Pipe",
]
import logging
from checkbox.lib.file import File
from checkbox.io.selector import (
Selector,
SelectorIO,
)
from checkbox.io.stream import Stream
# Number of bytes in atomic write to a pipe.
PIPE_BUF = 2 ** 12
class Pipe(Stream):
__slots__ = (
"_fd",
"_bytes",
"_reader",
"_writer",
"_watchdog_client",
"_watchdog_server",
)
_buffer_size = PIPE_BUF
def __init__(self):
super(Pipe, self).__init__()
self._fd = None
self._bytes = ""
self._reader = File()
self._writer = File()
self._watchdog_client = None
self._watchdog_server = None
def fileno(self):
return self._fd
def get_description(self):
if self._fd is None:
return None
return "fd:%d" % self._fd
def connect_to_fd(self, fd):
self._fd = fd
return self._writer.initialize_from_fd(fd, "w")
def listen_on_fd(self, fd):
self._fd = fd
return self._reader.initialize_from_fd(fd, "r")
def handle_incoming_message(self):
"""Receive messages from the reader and buffer them.
:return: Whether a message becomes ready.
"""
bytes = self.get_bytes_raw(PIPE_BUF)
if bytes is None:
return False
self._bytes += bytes
return True
def get_bytes(self, size=-1):
"""See Stream.get_bytes"""
if size < 0:
size = self._buffer_size
else:
size = min(size, self._buffer_size)
while size > len(self._bytes):
if not self.handle_incoming_message():
break
size = min(size, len(self._bytes))
bytes = self._bytes[:size]
self._bytes = self._bytes[size:]
return bytes
def get_bytes_raw(self, size):
"""Get bytes directly from the source.
:param size: Number of bytes to get.
:return: Bytes gotten.
"""
read_fd = self._reader.fileno()
selector = Selector()
selector.set_timeout(self._timeout)
selector.add_fd(read_fd, SelectorIO.READ)
# Select with both the real and watchdog descriptors
if self._watchdog_client:
selector.add_fd(self._watchdog_client.fileno(), SelectorIO.READ)
selector.execute()
if selector.has_timed_out:
return None
elif not selector.has_ready:
return None
if (self._watchdog_client and
selector.check_fd(
self._watchdog_client.fileno(), SelectorIO.READ) and
not selector.check_fd(read_fd, SelectorIO.READ)):
logging.info("Error reading from source, watchdog side closed")
return None
bytes = self._reader.read(size)
if bytes is None:
logging.info(
"Error reading from source, errno %d", self._reader.errno)
return bytes
def get_end(self):
return True
def peek(self):
"""See Stream.peek"""
while not self._bytes:
if not self.handle_incoming_message():
return None
return self._bytes[0]
def search(self, sub):
"""See Stream.search"""
bytes = ""
position = 0
while True:
index = self._bytes.find(sub, position)
if index >= 0:
bytes = self._bytes[:index]
self._bytes = self._bytes[index + len(sub):]
break
position = len(self._bytes)
if not self.handle_incoming_message():
return None
return bytes
def put_bytes(self, bytes):
"""See Stream.put_bytes"""
if len(bytes) > self._buffer_size:
bytes = bytes[:self._buffer_size]
return self.put_bytes_raw(bytes)
def put_bytes_raw(self, bytes):
"""Put bytes directly onto the destination.
:param bytes: Bytes to put.
:return: Number of bytes put.
"""
# Select with both the real and watchdog descriptors
if self._watchdog_client:
writer_fd = self._writer.fileno()
watchdog_fd = self._watchdog_client.fileno()
selector = Selector()
selector.add_fd(writer_fd, SelectorIO.WRITE)
selector.add_fd(watchdog_fd, SelectorIO.READ)
selector.execute()
if not selector.has_ready:
logging.info("Put bytes failed")
return -1
if selector.check_fd(watchdog_fd, SelectorIO.READ):
logging.info("Error writing to fifo, watchdog side closed")
return -1
size = self._writer.write(bytes)
if size < 0:
logging.info(
"Error writing to fifo, errno %d", self._writer.errno)
return size
def put_end(self):
return True
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