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# Copyright (c) 2016 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.
import os
import ctypes
from ctypes.util import find_library
import six
__all__ = ['linkat']
class Linkat(object):
# From include/uapi/linux/fcntl.h
AT_FDCWD = -100
AT_SYMLINK_FOLLOW = 0x400
__slots__ = '_c_linkat'
def __init__(self):
libc = ctypes.CDLL(find_library('c'), use_errno=True)
try:
c_linkat = libc.linkat
except AttributeError:
self._c_linkat = None
return
c_linkat.argtypes = [ctypes.c_int, ctypes.c_char_p,
ctypes.c_int, ctypes.c_char_p,
ctypes.c_int]
c_linkat.restype = ctypes.c_int
def errcheck(result, func, arguments):
if result == -1:
errno = ctypes.set_errno(0)
raise IOError(errno, 'linkat: %s' % os.strerror(errno))
else:
return result
c_linkat.errcheck = errcheck
self._c_linkat = c_linkat
@property
def available(self):
return self._c_linkat is not None
def __call__(self, olddirfd, oldpath, newdirfd, newpath, flags):
"""
linkat() creates a new link (also known as a hard link)
to an existing file.
See `man 2 linkat` for more info.
"""
if not self.available:
raise EnvironmentError('linkat not available')
if not isinstance(olddirfd, int) or not isinstance(newdirfd, int):
raise TypeError("fd must be an integer.")
if isinstance(oldpath, six.text_type):
oldpath = oldpath.encode('utf8')
if isinstance(newpath, six.text_type):
newpath = newpath.encode('utf8')
return self._c_linkat(olddirfd, oldpath, newdirfd, newpath, flags)
linkat = Linkat()
del Linkat
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