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# Copyright (c) 2014 OpenStack Foundation
#
# 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.
'''
Bindings to the `tee` and `splice` system calls
'''
import os
import operator
import six
import ctypes
import ctypes.util
__all__ = ['tee', 'splice']
c_loff_t = ctypes.c_long
class Tee(object):
'''Binding to `tee`'''
__slots__ = '_c_tee',
def __init__(self):
libc = ctypes.CDLL(ctypes.util.find_library('c'), use_errno=True)
try:
c_tee = libc.tee
except AttributeError:
self._c_tee = None
return
c_tee.argtypes = [
ctypes.c_int,
ctypes.c_int,
ctypes.c_size_t,
ctypes.c_uint
]
c_tee.restype = ctypes.c_ssize_t
def errcheck(result, func, arguments):
if result == -1:
errno = ctypes.set_errno(0)
raise IOError(errno, 'tee: %s' % os.strerror(errno))
else:
return result
c_tee.errcheck = errcheck
self._c_tee = c_tee
def __call__(self, fd_in, fd_out, len_, flags):
'''See `man 2 tee`
File-descriptors can be file-like objects with a `fileno` method, or
integers.
Flags can be an integer value, or a list of flags (exposed on
`splice`).
This function returns the number of bytes transferred (i.e. the actual
result of the call to `tee`).
Upon other errors, an `IOError` is raised with the proper `errno` set.
'''
if not self.available:
raise EnvironmentError('tee not available')
if not isinstance(flags, six.integer_types):
c_flags = six.moves.reduce(operator.or_, flags, 0)
else:
c_flags = flags
c_fd_in = getattr(fd_in, 'fileno', lambda: fd_in)()
c_fd_out = getattr(fd_out, 'fileno', lambda: fd_out)()
return self._c_tee(c_fd_in, c_fd_out, len_, c_flags)
@property
def available(self):
'''Availability of `tee`'''
return self._c_tee is not None
tee = Tee()
del Tee
class Splice(object):
'''Binding to `splice`'''
# From `bits/fcntl-linux.h`
SPLICE_F_MOVE = 1
SPLICE_F_NONBLOCK = 2
SPLICE_F_MORE = 4
SPLICE_F_GIFT = 8
__slots__ = '_c_splice',
def __init__(self):
libc = ctypes.CDLL(ctypes.util.find_library('c'), use_errno=True)
try:
c_splice = libc.splice
except AttributeError:
self._c_splice = None
return
c_loff_t_p = ctypes.POINTER(c_loff_t)
c_splice.argtypes = [
ctypes.c_int, c_loff_t_p,
ctypes.c_int, c_loff_t_p,
ctypes.c_size_t,
ctypes.c_uint
]
c_splice.restype = ctypes.c_ssize_t
def errcheck(result, func, arguments):
if result == -1:
errno = ctypes.set_errno(0)
raise IOError(errno, 'splice: %s' % os.strerror(errno))
else:
off_in = arguments[1]
off_out = arguments[3]
return (
result,
off_in.contents.value if off_in is not None else None,
off_out.contents.value if off_out is not None else None)
c_splice.errcheck = errcheck
self._c_splice = c_splice
def __call__(self, fd_in, off_in, fd_out, off_out, len_, flags):
'''See `man 2 splice`
File-descriptors can be file-like objects with a `fileno` method, or
integers.
Flags can be an integer value, or a list of flags (exposed on this
object).
Returns a tuple of the result of the `splice` call, the output value of
`off_in` and the output value of `off_out` (or `None` for any of these
output values, if applicable).
Upon other errors, an `IOError` is raised with the proper `errno` set.
Note: if you want to pass `NULL` as value for `off_in` or `off_out` to
the system call, you must pass `None`, *not* 0!
'''
if not self.available:
raise EnvironmentError('splice not available')
if not isinstance(flags, six.integer_types):
c_flags = six.moves.reduce(operator.or_, flags, 0)
else:
c_flags = flags
c_fd_in = getattr(fd_in, 'fileno', lambda: fd_in)()
c_fd_out = getattr(fd_out, 'fileno', lambda: fd_out)()
c_off_in = \
ctypes.pointer(c_loff_t(off_in)) if off_in is not None else None
c_off_out = \
ctypes.pointer(c_loff_t(off_out)) if off_out is not None else None
return self._c_splice(
c_fd_in, c_off_in, c_fd_out, c_off_out, len_, c_flags)
@property
def available(self):
'''Availability of `splice`'''
return self._c_splice is not None
splice = Splice()
del Splice
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