308 lines
12 KiB
Python
308 lines
12 KiB
Python
# Copyright (C) 2003-2005 Robey Pointer <robey@lag.net>
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#
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# This file is part of paramiko.
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#
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# Paramiko is free software; you can redistribute it and/or modify it under the
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# terms of the GNU Lesser General Public License as published by the Free
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# Software Foundation; either version 2.1 of the License, or (at your option)
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# any later version.
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#
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# Paramiko is distrubuted in the hope that it will be useful, but WITHOUT ANY
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# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
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# A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
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# details.
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#
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# You should have received a copy of the GNU Lesser General Public License
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# along with Paramiko; if not, write to the Free Software Foundation, Inc.,
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# 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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"""
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L{SFTPFile}
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"""
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import threading
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from paramiko.common import *
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from paramiko.sftp import *
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from paramiko.file import BufferedFile
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from paramiko.sftp_attr import SFTPAttributes
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class SFTPFile (BufferedFile):
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"""
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Proxy object for a file on the remote server, in client mode SFTP.
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"""
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# Some sftp servers will choke if you send read/write requests larger than
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# this size.
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MAX_REQUEST_SIZE = 32768
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def __init__(self, sftp, handle, mode='r', bufsize=-1):
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BufferedFile.__init__(self)
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self.sftp = sftp
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self.handle = handle
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BufferedFile._set_mode(self, mode, bufsize)
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self.pipelined = False
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self._prefetching = False
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self._saved_exception = None
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def __del__(self):
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self.close(_async=True)
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def close(self, _async=False):
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# We allow double-close without signaling an error, because real
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# Python file objects do. However, we must protect against actually
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# sending multiple CMD_CLOSE packets, because after we close our
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# handle, the same handle may be re-allocated by the server, and we
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# may end up mysteriously closing some random other file. (This is
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# especially important because we unconditionally call close() from
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# __del__.)
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if self._closed:
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return
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if self.pipelined:
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self.sftp._finish_responses(self)
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BufferedFile.close(self)
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try:
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if _async:
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# GC'd file handle could be called from an arbitrary thread -- don't wait for a response
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self.sftp._async_request(type(None), CMD_CLOSE, self.handle)
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else:
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self.sftp._request(CMD_CLOSE, self.handle)
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except EOFError:
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# may have outlived the Transport connection
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pass
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except IOError:
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# may have outlived the Transport connection
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pass
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def _read_prefetch(self, size):
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# while not closed, and haven't fetched past the current position, and haven't reached EOF...
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while (self._prefetch_so_far <= self._realpos) and \
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(self._prefetch_so_far < self._prefetch_size) and not self._closed:
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self.sftp._read_response()
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self._check_exception()
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k = self._prefetch_data.keys()
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k.sort()
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while (len(k) > 0) and (k[0] + len(self._prefetch_data[k[0]]) <= self._realpos):
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# done with that block
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del self._prefetch_data[k[0]]
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k.pop(0)
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if len(k) == 0:
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self._prefetching = False
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return ''
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assert k[0] <= self._realpos
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buf_offset = self._realpos - k[0]
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buf_length = len(self._prefetch_data[k[0]]) - buf_offset
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return self._prefetch_data[k[0]][buf_offset : buf_offset + buf_length]
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def _read(self, size):
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size = min(size, self.MAX_REQUEST_SIZE)
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if self._prefetching:
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return self._read_prefetch(size)
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t, msg = self.sftp._request(CMD_READ, self.handle, long(self._realpos), int(size))
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if t != CMD_DATA:
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raise SFTPError('Expected data')
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return msg.get_string()
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def _write(self, data):
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# may write less than requested if it would exceed max packet size
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chunk = min(len(data), self.MAX_REQUEST_SIZE)
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req = self.sftp._async_request(type(None), CMD_WRITE, self.handle, long(self._realpos),
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str(data[:chunk]))
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if not self.pipelined or self.sftp.sock.recv_ready():
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t, msg = self.sftp._read_response(req)
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if t != CMD_STATUS:
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raise SFTPError('Expected status')
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# convert_status already called
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return chunk
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def settimeout(self, timeout):
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"""
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Set a timeout on read/write operations on the underlying socket or
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ssh L{Channel}.
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@see: L{Channel.settimeout}
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@param timeout: seconds to wait for a pending read/write operation
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before raising C{socket.timeout}, or C{None} for no timeout
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@type timeout: float
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"""
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self.sftp.sock.settimeout(timeout)
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def gettimeout(self):
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"""
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Returns the timeout in seconds (as a float) associated with the socket
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or ssh L{Channel} used for this file.
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@see: L{Channel.gettimeout}
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@rtype: float
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"""
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return self.sftp.sock.gettimeout()
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def setblocking(self, blocking):
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"""
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Set blocking or non-blocking mode on the underiying socket or ssh
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L{Channel}.
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@see: L{Channel.setblocking}
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@param blocking: 0 to set non-blocking mode; non-0 to set blocking
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mode.
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@type blocking: int
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"""
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self.sftp.sock.setblocking(blocking)
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def seek(self, offset, whence=0):
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self.flush()
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if whence == self.SEEK_SET:
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self._realpos = self._pos = offset
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elif whence == self.SEEK_CUR:
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self._pos += offset
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self._realpos = self._pos
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else:
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self._realpos = self._pos = self._get_size() + offset
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self._rbuffer = ''
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def stat(self):
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"""
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Retrieve information about this file from the remote system. This is
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exactly like L{SFTP.stat}, except that it operates on an already-open
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file.
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@return: an object containing attributes about this file.
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@rtype: SFTPAttributes
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"""
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t, msg = self.sftp._request(CMD_FSTAT, self.handle)
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if t != CMD_ATTRS:
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raise SFTPError('Expected attributes')
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return SFTPAttributes._from_msg(msg)
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def check(self, hash_algorithm, offset=0, length=0, block_size=0):
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"""
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Ask the server for a hash of a section of this file. This can be used
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to verify a successful upload or download, or for various rsync-like
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operations.
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The file is hashed from C{offset}, for C{length} bytes. If C{length}
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is 0, the remainder of the file is hashed. Thus, if both C{offset}
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and C{length} are zero, the entire file is hashed.
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Normally, C{block_size} will be 0 (the default), and this method will
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return a byte string representing the requested hash (for example, a
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string of length 16 for MD5, or 20 for SHA-1). If a non-zero
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C{block_size} is given, each chunk of the file (from C{offset} to
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C{offset + length}) of C{block_size} bytes is computed as a separate
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hash. The hash results are all concatenated and returned as a single
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string.
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For example, C{check('sha1', 0, 1024, 512)} will return a string of
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length 40. The first 20 bytes will be the SHA-1 of the first 512 bytes
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of the file, and the last 20 bytes will be the SHA-1 of the next 512
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bytes.
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@param hash_algorithm: the name of the hash algorithm to use (normally
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C{"sha1"} or C{"md5"})
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@type hash_algorithm: str
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@param offset: offset into the file to begin hashing (0 means to start
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from the beginning)
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@type offset: int or long
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@param length: number of bytes to hash (0 means continue to the end of
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the file)
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@type length: int or long
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@param block_size: number of bytes to hash per result (must not be less
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than 256; 0 means to compute only one hash of the entire segment)
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@type block_size: int
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@return: string of bytes representing the hash of each block,
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concatenated together
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@rtype: str
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@note: Many (most?) servers don't support this extension yet.
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@raise IOError: if the server doesn't support the "check-file"
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extension, or possibly doesn't support the hash algorithm
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requested
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@since: 1.4
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"""
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t, msg = self.sftp._request(CMD_EXTENDED, 'check-file', self.handle,
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hash_algorithm, long(offset), long(length), block_size)
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ext = msg.get_string()
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alg = msg.get_string()
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data = msg.get_remainder()
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return data
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def set_pipelined(self, pipelined=True):
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"""
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Turn on/off the pipelining of write operations to this file. When
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pipelining is on, paramiko won't wait for the server response after
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each write operation. Instead, they're collected as they come in.
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At the first non-write operation (including L{close}), all remaining
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server responses are collected. This means that if there was an error
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with one of your later writes, an exception might be thrown from
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within L{close} instead of L{write}.
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By default, files are I{not} pipelined.
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@param pipelined: C{True} if pipelining should be turned on for this
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file; C{False} otherwise
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@type pipelined: bool
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@since: 1.5
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"""
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self.pipelined = pipelined
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def prefetch(self):
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"""
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Pre-fetch the remaining contents of this file in anticipation of
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future L{read} calls. If reading the entire file, pre-fetching can
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dramatically improve the download speed by avoiding roundtrip latency.
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The file's contents are incrementally buffered in a background thread.
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@since: 1.5.1
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"""
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size = self.stat().st_size
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# queue up async reads for the rest of the file
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self._prefetching = True
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self._prefetch_so_far = self._realpos
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self._prefetch_size = size
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self._prefetch_data = {}
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t = threading.Thread(target=self._prefetch)
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t.setDaemon(True)
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t.start()
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def _prefetch(self):
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n = self._realpos
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size = self._prefetch_size
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while n < size:
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chunk = min(self.MAX_REQUEST_SIZE, size - n)
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self.sftp._async_request(self, CMD_READ, self.handle, long(n), int(chunk))
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n += chunk
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### internals...
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def _get_size(self):
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try:
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return self.stat().st_size
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except:
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return 0
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def _async_response(self, t, msg):
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if t == CMD_STATUS:
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# save exception and re-raise it on next file operation
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try:
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self.sftp._convert_status(msg)
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except Exception, x:
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self._saved_exception = x
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return
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if t != CMD_DATA:
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raise SFTPError('Expected data')
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data = msg.get_string()
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self._prefetch_data[self._prefetch_so_far] = data
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self._prefetch_so_far += len(data)
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def _check_exception(self):
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"if there's a saved exception, raise & clear it"
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if self._saved_exception is not None:
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x = self._saved_exception
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self._saved_exception = None
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raise x
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