Current File : //lib/python3/dist-packages/paramiko/sftp_handle.py
# Copyright (C) 2003-2007 Robey Pointer <robeypointer@gmail.com>
#
# This file is part of paramiko.
#
# Paramiko 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.
#
# Paramiko 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 Paramiko; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
"""
Abstraction of an SFTP file handle (for server mode).
"""
import os
from paramiko.sftp import SFTP_OP_UNSUPPORTED, SFTP_OK
from paramiko.util import ClosingContextManager
class SFTPHandle(ClosingContextManager):
"""
Abstract object representing a handle to an open file (or folder) in an
SFTP server implementation. Each handle has a string representation used
by the client to refer to the underlying file.
Server implementations can (and should) subclass SFTPHandle to implement
features of a file handle, like `stat` or `chattr`.
Instances of this class may be used as context managers.
"""
def __init__(self, flags=0):
"""
Create a new file handle representing a local file being served over
SFTP. If ``flags`` is passed in, it's used to determine if the file
is open in append mode.
:param int flags: optional flags as passed to
`.SFTPServerInterface.open`
"""
self.__flags = flags
self.__name = None
# only for handles to folders:
self.__files = {}
self.__tell = None
def close(self):
"""
When a client closes a file, this method is called on the handle.
Normally you would use this method to close the underlying OS level
file object(s).
The default implementation checks for attributes on ``self`` named
``readfile`` and/or ``writefile``, and if either or both are present,
their ``close()`` methods are called. This means that if you are
using the default implementations of `read` and `write`, this
method's default implementation should be fine also.
"""
readfile = getattr(self, "readfile", None)
if readfile is not None:
readfile.close()
writefile = getattr(self, "writefile", None)
if writefile is not None:
writefile.close()
def read(self, offset, length):
"""
Read up to ``length`` bytes from this file, starting at position
``offset``. The offset may be a Python long, since SFTP allows it
to be 64 bits.
If the end of the file has been reached, this method may return an
empty string to signify EOF, or it may also return ``SFTP_EOF``.
The default implementation checks for an attribute on ``self`` named
``readfile``, and if present, performs the read operation on the Python
file-like object found there. (This is meant as a time saver for the
common case where you are wrapping a Python file object.)
:param offset: position in the file to start reading from.
:param int length: number of bytes to attempt to read.
:return: data read from the file, or an SFTP error code, as a `str`.
"""
readfile = getattr(self, "readfile", None)
if readfile is None:
return SFTP_OP_UNSUPPORTED
try:
if self.__tell is None:
self.__tell = readfile.tell()
if offset != self.__tell:
readfile.seek(offset)
self.__tell = offset
data = readfile.read(length)
except IOError as e:
self.__tell = None
return SFTPServer.convert_errno(e.errno)
self.__tell += len(data)
return data
def write(self, offset, data):
"""
Write ``data`` into this file at position ``offset``. Extending the
file past its original end is expected. Unlike Python's normal
``write()`` methods, this method cannot do a partial write: it must
write all of ``data`` or else return an error.
The default implementation checks for an attribute on ``self`` named
``writefile``, and if present, performs the write operation on the
Python file-like object found there. The attribute is named
differently from ``readfile`` to make it easy to implement read-only
(or write-only) files, but if both attributes are present, they should
refer to the same file.
:param offset: position in the file to start reading from.
:param str data: data to write into the file.
:return: an SFTP error code like ``SFTP_OK``.
"""
writefile = getattr(self, "writefile", None)
if writefile is None:
return SFTP_OP_UNSUPPORTED
try:
# in append mode, don't care about seeking
if (self.__flags & os.O_APPEND) == 0:
if self.__tell is None:
self.__tell = writefile.tell()
if offset != self.__tell:
writefile.seek(offset)
self.__tell = offset
writefile.write(data)
writefile.flush()
except IOError as e:
self.__tell = None
return SFTPServer.convert_errno(e.errno)
if self.__tell is not None:
self.__tell += len(data)
return SFTP_OK
def stat(self):
"""
Return an `.SFTPAttributes` object referring to this open file, or an
error code. This is equivalent to `.SFTPServerInterface.stat`, except
it's called on an open file instead of a path.
:return:
an attributes object for the given file, or an SFTP error code
(like ``SFTP_PERMISSION_DENIED``).
:rtype: `.SFTPAttributes` or error code
"""
return SFTP_OP_UNSUPPORTED
def chattr(self, attr):
"""
Change the attributes of this file. The ``attr`` object will contain
only those fields provided by the client in its request, so you should
check for the presence of fields before using them.
:param .SFTPAttributes attr: the attributes to change on this file.
:return: an `int` error code like ``SFTP_OK``.
"""
return SFTP_OP_UNSUPPORTED
# ...internals...
def _set_files(self, files):
"""
Used by the SFTP server code to cache a directory listing. (In
the SFTP protocol, listing a directory is a multi-stage process
requiring a temporary handle.)
"""
self.__files = files
def _get_next_files(self):
"""
Used by the SFTP server code to retrieve a cached directory
listing.
"""
fnlist = self.__files[:16]
self.__files = self.__files[16:]
return fnlist
def _get_name(self):
return self.__name
def _set_name(self, name):
self.__name = name
from paramiko.sftp_server import SFTPServer
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