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# Copyright (c) 2010, 2012 Nicira Networks
#
# 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 errno
import os
import select
import socket
import sys
import ovs.fatal_signal
import ovs.vlog
vlog = ovs.vlog.Vlog("socket_util")
def make_unix_socket(style, nonblock, bind_path, connect_path):
"""Creates a Unix domain socket in the given 'style' (either
socket.SOCK_DGRAM or socket.SOCK_STREAM) that is bound to 'bind_path' (if
'bind_path' is not None) and connected to 'connect_path' (if 'connect_path'
is not None). If 'nonblock' is true, the socket is made non-blocking.
Returns (error, socket): on success 'error' is 0 and 'socket' is a new
socket object, on failure 'error' is a positive errno value and 'socket' is
None."""
try:
sock = socket.socket(socket.AF_UNIX, style)
except socket.error, e:
return get_exception_errno(e), None
try:
if nonblock:
set_nonblocking(sock)
if bind_path is not None:
# Delete bind_path but ignore ENOENT.
try:
os.unlink(bind_path)
except OSError, e:
if e.errno != errno.ENOENT:
return e.errno, None
ovs.fatal_signal.add_file_to_unlink(bind_path)
sock.bind(bind_path)
try:
if sys.hexversion >= 0x02060000:
os.fchmod(sock.fileno(), 0700)
else:
os.chmod("/dev/fd/%d" % sock.fileno(), 0700)
except OSError, e:
pass
if connect_path is not None:
try:
sock.connect(connect_path)
except socket.error, e:
if get_exception_errno(e) != errno.EINPROGRESS:
raise
return 0, sock
except socket.error, e:
sock.close()
if bind_path is not None:
ovs.fatal_signal.unlink_file_now(bind_path)
return get_exception_errno(e), None
def check_connection_completion(sock):
p = select.poll()
p.register(sock, select.POLLOUT)
if len(p.poll(0)) == 1:
return get_socket_error(sock)
else:
return errno.EAGAIN
def get_socket_error(sock):
"""Returns the errno value associated with 'socket' (0 if no error) and
resets the socket's error status."""
return sock.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR)
def get_exception_errno(e):
"""A lot of methods on Python socket objects raise socket.error, but that
exception is documented as having two completely different forms of
arguments: either a string or a (errno, string) tuple. We only want the
errno."""
if type(e.args) == tuple:
return e.args[0]
else:
return errno.EPROTO
null_fd = -1
def get_null_fd():
"""Returns a readable and writable fd for /dev/null, if successful,
otherwise a negative errno value. The caller must not close the returned
fd (because the same fd will be handed out to subsequent callers)."""
global null_fd
if null_fd < 0:
try:
null_fd = os.open("/dev/null", os.O_RDWR)
except OSError, e:
vlog.err("could not open /dev/null: %s" % os.strerror(e.errno))
return -e.errno
return null_fd
def write_fully(fd, buf):
"""Returns an (error, bytes_written) tuple where 'error' is 0 on success,
otherwise a positive errno value, and 'bytes_written' is the number of
bytes that were written before the error occurred. 'error' is 0 if and
only if 'bytes_written' is len(buf)."""
bytes_written = 0
if len(buf) == 0:
return 0, 0
while True:
try:
retval = os.write(fd, buf)
assert retval >= 0
if retval == len(buf):
return 0, bytes_written + len(buf)
elif retval == 0:
vlog.warn("write returned 0")
return errno.EPROTO, bytes_written
else:
bytes_written += retval
buf = buf[:retval]
except OSError, e:
return e.errno, bytes_written
def set_nonblocking(sock):
try:
sock.setblocking(0)
except socket.error, e:
vlog.err("could not set nonblocking mode on socket: %s"
% os.strerror(get_socket_error(e)))
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