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5380dea2a7
Python 2.6 introduced the "except type as instance" syntax, replacing the "except type, instance" syntax that came before. Python 3 dropped support for the latter syntax. Since we no longer support Python 2.4 or 2.5, we have no need to continue supporting the "except type, instance". This patch mass rewrites the exception syntax to be Python 2.6+ and Python 3 compatible. This patch was produced by running `2to3 -f except -w -n .`.
464 lines
16 KiB
Python
464 lines
16 KiB
Python
# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, see
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# <http://www.gnu.org/licenses/>.
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# This file is part of urlgrabber, a high-level cross-protocol url-grabber
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# Copyright 2002-2004 Michael D. Stenner, Ryan Tomayko
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# $Id: byterange.py,v 1.9 2005/02/14 21:55:07 mstenner Exp $
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import os
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import stat
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import urllib
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import urllib2
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import email.Utils
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class RangeError(IOError):
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"""Error raised when an unsatisfiable range is requested."""
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pass
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class HTTPRangeHandler(urllib2.BaseHandler):
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"""Handler that enables HTTP Range headers.
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This was extremely simple. The Range header is a HTTP feature to
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begin with so all this class does is tell urllib2 that the
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"206 Partial Content" response from the HTTP server is what we
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expected.
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Example:
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import urllib2
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import byterange
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range_handler = range.HTTPRangeHandler()
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opener = urllib2.build_opener(range_handler)
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# install it
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urllib2.install_opener(opener)
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# create Request and set Range header
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req = urllib2.Request('http://www.python.org/')
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req.header['Range'] = 'bytes=30-50'
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f = urllib2.urlopen(req)
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"""
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def http_error_206(self, req, fp, code, msg, hdrs):
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# 206 Partial Content Response
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r = urllib.addinfourl(fp, hdrs, req.get_full_url())
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r.code = code
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r.msg = msg
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return r
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def http_error_416(self, req, fp, code, msg, hdrs):
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# HTTP's Range Not Satisfiable error
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raise RangeError('Requested Range Not Satisfiable')
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class RangeableFileObject(object):
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"""File object wrapper to enable raw range handling.
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This was implemented primarily for handling range
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specifications for file:// urls. This object effectively makes
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a file object look like it consists only of a range of bytes in
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the stream.
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Examples:
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# expose 10 bytes, starting at byte position 20, from
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# /etc/aliases.
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>>> fo = RangeableFileObject(file('/etc/passwd', 'r'), (20,30))
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# seek seeks within the range (to position 23 in this case)
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>>> fo.seek(3)
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# tell tells where your at _within the range_ (position 3 in
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# this case)
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>>> fo.tell()
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# read EOFs if an attempt is made to read past the last
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# byte in the range. the following will return only 7 bytes.
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>>> fo.read(30)
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"""
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def __init__(self, fo, rangetup):
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"""Create a RangeableFileObject.
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fo -- a file like object. only the read() method need be
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supported but supporting an optimized seek() is
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preferable.
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rangetup -- a (firstbyte,lastbyte) tuple specifying the range
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to work over.
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The file object provided is assumed to be at byte offset 0.
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"""
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self.fo = fo
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(self.firstbyte, self.lastbyte) = range_tuple_normalize(rangetup)
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self.realpos = 0
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self._do_seek(self.firstbyte)
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def __getattr__(self, name):
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"""This effectively allows us to wrap at the instance level.
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Any attribute not found in _this_ object will be searched for
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in self.fo. This includes methods."""
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return getattr(self.fo, name)
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def tell(self):
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"""Return the position within the range.
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This is different from fo.seek in that position 0 is the
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first byte position of the range tuple. For example, if
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this object was created with a range tuple of (500,899),
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tell() will return 0 when at byte position 500 of the file.
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"""
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return (self.realpos - self.firstbyte)
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def seek(self, offset, whence=0):
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"""Seek within the byte range.
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Positioning is identical to that described under tell().
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"""
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assert whence in (0, 1, 2)
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if whence == 0: # absolute seek
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realoffset = self.firstbyte + offset
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elif whence == 1: # relative seek
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realoffset = self.realpos + offset
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elif whence == 2: # absolute from end of file
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# XXX: are we raising the right Error here?
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raise IOError('seek from end of file not supported.')
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# do not allow seek past lastbyte in range
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if self.lastbyte and (realoffset >= self.lastbyte):
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realoffset = self.lastbyte
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self._do_seek(realoffset - self.realpos)
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def read(self, size=-1):
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"""Read within the range.
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This method will limit the size read based on the range.
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"""
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size = self._calc_read_size(size)
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rslt = self.fo.read(size)
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self.realpos += len(rslt)
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return rslt
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def readline(self, size=-1):
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"""Read lines within the range.
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This method will limit the size read based on the range.
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"""
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size = self._calc_read_size(size)
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rslt = self.fo.readline(size)
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self.realpos += len(rslt)
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return rslt
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def _calc_read_size(self, size):
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"""Handles calculating the amount of data to read based on
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the range.
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"""
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if self.lastbyte:
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if size > -1:
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if ((self.realpos + size) >= self.lastbyte):
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size = (self.lastbyte - self.realpos)
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else:
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size = (self.lastbyte - self.realpos)
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return size
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def _do_seek(self, offset):
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"""Seek based on whether wrapped object supports seek().
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offset is relative to the current position (self.realpos).
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"""
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assert offset >= 0
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seek = getattr(self.fo, 'seek', self._poor_mans_seek)
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seek(self.realpos + offset)
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self.realpos += offset
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def _poor_mans_seek(self, offset):
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"""Seek by calling the wrapped file objects read() method.
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This is used for file like objects that do not have native
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seek support. The wrapped objects read() method is called
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to manually seek to the desired position.
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offset -- read this number of bytes from the wrapped
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file object.
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raise RangeError if we encounter EOF before reaching the
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specified offset.
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"""
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pos = 0
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bufsize = 1024
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while pos < offset:
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if (pos + bufsize) > offset:
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bufsize = offset - pos
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buf = self.fo.read(bufsize)
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if len(buf) != bufsize:
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raise RangeError('Requested Range Not Satisfiable')
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pos += bufsize
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class FileRangeHandler(urllib2.FileHandler):
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"""FileHandler subclass that adds Range support.
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This class handles Range headers exactly like an HTTP
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server would.
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"""
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def open_local_file(self, req):
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import mimetypes
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import email
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host = req.get_host()
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file = req.get_selector()
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localfile = urllib.url2pathname(file)
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stats = os.stat(localfile)
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size = stats[stat.ST_SIZE]
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modified = email.Utils.formatdate(stats[stat.ST_MTIME])
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mtype = mimetypes.guess_type(file)[0]
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if host:
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host, port = urllib.splitport(host)
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if port or socket.gethostbyname(host) not in self.get_names():
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raise urllib2.URLError('file not on local host')
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fo = open(localfile,'rb')
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brange = req.headers.get('Range', None)
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brange = range_header_to_tuple(brange)
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assert brange != ()
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if brange:
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(fb, lb) = brange
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if lb == '':
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lb = size
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if fb < 0 or fb > size or lb > size:
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raise RangeError('Requested Range Not Satisfiable')
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size = (lb - fb)
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fo = RangeableFileObject(fo, (fb, lb))
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headers = email.message_from_string(
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'Content-Type: %s\nContent-Length: %d\nLast-Modified: %s\n' %
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(mtype or 'text/plain', size, modified))
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return urllib.addinfourl(fo, headers, 'file:'+file)
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# FTP Range Support
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# Unfortunately, a large amount of base FTP code had to be copied
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# from urllib and urllib2 in order to insert the FTP REST command.
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# Code modifications for range support have been commented as
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# follows:
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# -- range support modifications start/end here
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from urllib import splitport, splituser, splitpasswd, splitattr, \
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unquote, addclosehook, addinfourl
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import ftplib
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import socket
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import mimetypes
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import email
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class FTPRangeHandler(urllib2.FTPHandler):
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def ftp_open(self, req):
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host = req.get_host()
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if not host:
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raise IOError('ftp error', 'no host given')
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host, port = splitport(host)
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if port is None:
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port = ftplib.FTP_PORT
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else:
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port = int(port)
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# username/password handling
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user, host = splituser(host)
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if user:
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user, passwd = splitpasswd(user)
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else:
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passwd = None
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host = unquote(host)
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user = unquote(user or '')
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passwd = unquote(passwd or '')
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try:
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host = socket.gethostbyname(host)
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except socket.error as msg:
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raise urllib2.URLError(msg)
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path, attrs = splitattr(req.get_selector())
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dirs = path.split('/')
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dirs = map(unquote, dirs)
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dirs, file = dirs[:-1], dirs[-1]
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if dirs and not dirs[0]:
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dirs = dirs[1:]
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try:
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fw = self.connect_ftp(user, passwd, host, port, dirs)
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if file:
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type = 'I'
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else:
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type = 'D'
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for attr in attrs:
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attr, value = splitattr(attr)
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if attr.lower() == 'type' and \
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value in ('a', 'A', 'i', 'I', 'd', 'D'):
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type = value.upper()
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# -- range support modifications start here
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rest = None
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range_tup = range_header_to_tuple(req.headers.get('Range', None))
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assert range_tup != ()
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if range_tup:
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(fb, lb) = range_tup
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if fb > 0:
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rest = fb
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# -- range support modifications end here
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fp, retrlen = fw.retrfile(file, type, rest)
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# -- range support modifications start here
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if range_tup:
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(fb, lb) = range_tup
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if lb == '':
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if retrlen is None or retrlen == 0:
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raise RangeError('Requested Range Not Satisfiable due'
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' to unobtainable file length.')
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lb = retrlen
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retrlen = lb - fb
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if retrlen < 0:
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# beginning of range is larger than file
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raise RangeError('Requested Range Not Satisfiable')
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else:
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retrlen = lb - fb
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fp = RangeableFileObject(fp, (0, retrlen))
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# -- range support modifications end here
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headers = ""
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mtype = mimetypes.guess_type(req.get_full_url())[0]
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if mtype:
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headers += "Content-Type: %s\n" % mtype
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if retrlen is not None and retrlen >= 0:
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headers += "Content-Length: %d\n" % retrlen
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headers = email.message_from_string(headers)
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return addinfourl(fp, headers, req.get_full_url())
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except ftplib.all_errors as msg:
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raise IOError('ftp error', msg)
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def connect_ftp(self, user, passwd, host, port, dirs):
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fw = ftpwrapper(user, passwd, host, port, dirs)
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return fw
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class ftpwrapper(urllib.ftpwrapper):
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# range support note:
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# this ftpwrapper code is copied directly from
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# urllib. The only enhancement is to add the rest
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# argument and pass it on to ftp.ntransfercmd
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def retrfile(self, file, type, rest=None):
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self.endtransfer()
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if type in ('d', 'D'):
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cmd = 'TYPE A'
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isdir = 1
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else:
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cmd = 'TYPE ' + type
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isdir = 0
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try:
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self.ftp.voidcmd(cmd)
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except ftplib.all_errors:
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self.init()
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self.ftp.voidcmd(cmd)
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conn = None
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if file and not isdir:
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# Use nlst to see if the file exists at all
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try:
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self.ftp.nlst(file)
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except ftplib.error_perm as reason:
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raise IOError('ftp error', reason)
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# Restore the transfer mode!
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self.ftp.voidcmd(cmd)
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# Try to retrieve as a file
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try:
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cmd = 'RETR ' + file
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conn = self.ftp.ntransfercmd(cmd, rest)
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except ftplib.error_perm as reason:
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if str(reason).startswith('501'):
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# workaround for REST not supported error
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fp, retrlen = self.retrfile(file, type)
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fp = RangeableFileObject(fp, (rest,''))
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return (fp, retrlen)
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elif not str(reason).startswith('550'):
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raise IOError('ftp error', reason)
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if not conn:
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# Set transfer mode to ASCII!
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self.ftp.voidcmd('TYPE A')
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# Try a directory listing
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if file:
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cmd = 'LIST ' + file
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else:
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cmd = 'LIST'
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conn = self.ftp.ntransfercmd(cmd)
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self.busy = 1
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# Pass back both a suitably decorated object and a retrieval length
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return (addclosehook(conn[0].makefile('rb'),
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self.endtransfer), conn[1])
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####################################################################
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# Range Tuple Functions
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# XXX: These range tuple functions might go better in a class.
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_rangere = None
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def range_header_to_tuple(range_header):
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"""Get a (firstbyte,lastbyte) tuple from a Range header value.
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Range headers have the form "bytes=<firstbyte>-<lastbyte>". This
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function pulls the firstbyte and lastbyte values and returns
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a (firstbyte,lastbyte) tuple. If lastbyte is not specified in
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the header value, it is returned as an empty string in the
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tuple.
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Return None if range_header is None
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Return () if range_header does not conform to the range spec
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pattern.
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"""
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global _rangere
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if range_header is None:
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return None
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if _rangere is None:
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import re
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_rangere = re.compile(r'^bytes=(\d{1,})-(\d*)')
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match = _rangere.match(range_header)
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if match:
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tup = range_tuple_normalize(match.group(1, 2))
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if tup and tup[1]:
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tup = (tup[0], tup[1]+1)
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return tup
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return ()
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def range_tuple_to_header(range_tup):
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"""Convert a range tuple to a Range header value.
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Return a string of the form "bytes=<firstbyte>-<lastbyte>" or None
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if no range is needed.
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"""
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if range_tup is None:
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return None
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range_tup = range_tuple_normalize(range_tup)
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if range_tup:
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if range_tup[1]:
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range_tup = (range_tup[0], range_tup[1] - 1)
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return 'bytes=%s-%s' % range_tup
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def range_tuple_normalize(range_tup):
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"""Normalize a (first_byte,last_byte) range tuple.
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Return a tuple whose first element is guaranteed to be an int
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and whose second element will be '' (meaning: the last byte) or
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an int. Finally, return None if the normalized tuple == (0,'')
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as that is equivalent to retrieving the entire file.
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"""
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if range_tup is None:
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return None
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# handle first byte
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fb = range_tup[0]
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if fb in (None, ''):
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fb = 0
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else:
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fb = int(fb)
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# handle last byte
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try:
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lb = range_tup[1]
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except IndexError:
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lb = ''
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else:
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if lb is None:
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lb = ''
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elif lb != '':
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lb = int(lb)
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# check if range is over the entire file
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if (fb, lb) == (0, ''):
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return None
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# check that the range is valid
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if lb < fb:
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raise RangeError('Invalid byte range: %s-%s' % (fb, lb))
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return (fb, lb)
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