--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial/byterange.py	Tue May 03 13:16:10 2005 -0800
@@ -0,0 +1,452 @@
+#   This library 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.
+#
+#   This library 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 this library; if not, write to the 
+#      Free Software Foundation, Inc., 
+#      59 Temple Place, Suite 330, 
+#      Boston, MA  02111-1307  USA
+
+# This file is part of urlgrabber, a high-level cross-protocol url-grabber
+# Copyright 2002-2004 Michael D. Stenner, Ryan Tomayko
+
+# $Id: byterange.py,v 1.9 2005/02/14 21:55:07 mstenner Exp $
+
+import os
+import stat
+import urllib
+import urllib2
+import rfc822
+
+try:    
+    from cStringIO import StringIO
+except ImportError, msg: 
+    from StringIO import StringIO
+
+class RangeError(IOError):
+    """Error raised when an unsatisfiable range is requested."""
+    pass
+    
+class HTTPRangeHandler(urllib2.BaseHandler):
+    """Handler that enables HTTP Range headers.
+    
+    This was extremely simple. The Range header is a HTTP feature to
+    begin with so all this class does is tell urllib2 that the 
+    "206 Partial Content" reponse from the HTTP server is what we 
+    expected.
+    
+    Example:
+        import urllib2
+        import byterange
+        
+        range_handler = range.HTTPRangeHandler()
+        opener = urllib2.build_opener(range_handler)
+        
+        # install it
+        urllib2.install_opener(opener)
+        
+        # create Request and set Range header
+        req = urllib2.Request('http://www.python.org/')
+        req.header['Range'] = 'bytes=30-50'
+        f = urllib2.urlopen(req)
+    """
+    
+    def http_error_206(self, req, fp, code, msg, hdrs):
+        # 206 Partial Content Response
+        r = urllib.addinfourl(fp, hdrs, req.get_full_url())
+        r.code = code
+        r.msg = msg
+        return r
+    
+    def http_error_416(self, req, fp, code, msg, hdrs):
+        # HTTP's Range Not Satisfiable error
+        raise RangeError('Requested Range Not Satisfiable')
+
+class RangeableFileObject:
+    """File object wrapper to enable raw range handling.
+    This was implemented primarilary for handling range 
+    specifications for file:// urls. This object effectively makes 
+    a file object look like it consists only of a range of bytes in 
+    the stream.
+    
+    Examples:
+        # expose 10 bytes, starting at byte position 20, from 
+        # /etc/aliases.
+        >>> fo = RangeableFileObject(file('/etc/passwd', 'r'), (20,30))
+        # seek seeks within the range (to position 23 in this case)
+        >>> fo.seek(3)
+        # tell tells where your at _within the range_ (position 3 in
+        # this case)
+        >>> fo.tell()
+        # read EOFs if an attempt is made to read past the last
+        # byte in the range. the following will return only 7 bytes.
+        >>> fo.read(30)
+    """
+    
+    def __init__(self, fo, rangetup):
+        """Create a RangeableFileObject.
+        fo       -- a file like object. only the read() method need be 
+                    supported but supporting an optimized seek() is 
+                    preferable.
+        rangetup -- a (firstbyte,lastbyte) tuple specifying the range
+                    to work over.
+        The file object provided is assumed to be at byte offset 0.
+        """
+        self.fo = fo
+        (self.firstbyte, self.lastbyte) = range_tuple_normalize(rangetup)
+        self.realpos = 0
+        self._do_seek(self.firstbyte)
+        
+    def __getattr__(self, name):
+        """This effectively allows us to wrap at the instance level.
+        Any attribute not found in _this_ object will be searched for
+        in self.fo.  This includes methods."""
+        if hasattr(self.fo, name):
+            return getattr(self.fo, name)
+        raise AttributeError, name
+    
+    def tell(self):
+        """Return the position within the range.
+        This is different from fo.seek in that position 0 is the 
+        first byte position of the range tuple. For example, if
+        this object was created with a range tuple of (500,899),
+        tell() will return 0 when at byte position 500 of the file.
+        """
+        return (self.realpos - self.firstbyte)
+    
+    def seek(self,offset,whence=0):
+        """Seek within the byte range.
+        Positioning is identical to that described under tell().
+        """
+        assert whence in (0, 1, 2)
+        if whence == 0:   # absolute seek
+            realoffset = self.firstbyte + offset
+        elif whence == 1: # relative seek
+            realoffset = self.realpos + offset
+        elif whence == 2: # absolute from end of file
+            # XXX: are we raising the right Error here?
+            raise IOError('seek from end of file not supported.')
+        
+        # do not allow seek past lastbyte in range
+        if self.lastbyte and (realoffset >= self.lastbyte):
+            realoffset = self.lastbyte
+        
+        self._do_seek(realoffset - self.realpos)
+        
+    def read(self, size=-1):
+        """Read within the range.
+        This method will limit the size read based on the range.
+        """
+        size = self._calc_read_size(size)
+        rslt = self.fo.read(size)
+        self.realpos += len(rslt)
+        return rslt
+    
+    def readline(self, size=-1):
+        """Read lines within the range.
+        This method will limit the size read based on the range.
+        """
+        size = self._calc_read_size(size)
+        rslt = self.fo.readline(size)
+        self.realpos += len(rslt)
+        return rslt
+    
+    def _calc_read_size(self, size):
+        """Handles calculating the amount of data to read based on
+        the range.
+        """
+        if self.lastbyte:
+            if size > -1:
+                if ((self.realpos + size) >= self.lastbyte):
+                    size = (self.lastbyte - self.realpos)
+            else:
+                size = (self.lastbyte - self.realpos)
+        return size
+        
+    def _do_seek(self,offset):
+        """Seek based on whether wrapped object supports seek().
+        offset is relative to the current position (self.realpos).
+        """
+        assert offset >= 0
+        if not hasattr(self.fo, 'seek'):
+            self._poor_mans_seek(offset)
+        else:
+            self.fo.seek(self.realpos + offset)
+        self.realpos+= offset
+        
+    def _poor_mans_seek(self,offset):
+        """Seek by calling the wrapped file objects read() method.
+        This is used for file like objects that do not have native
+        seek support. The wrapped objects read() method is called
+        to manually seek to the desired position.
+        offset -- read this number of bytes from the wrapped
+                  file object.
+        raise RangeError if we encounter EOF before reaching the 
+        specified offset.
+        """
+        pos = 0
+        bufsize = 1024
+        while pos < offset:
+            if (pos + bufsize) > offset:
+                bufsize = offset - pos
+            buf = self.fo.read(bufsize)
+            if len(buf) != bufsize:
+                raise RangeError('Requested Range Not Satisfiable')
+            pos+= bufsize
+
+class FileRangeHandler(urllib2.FileHandler):
+    """FileHandler subclass that adds Range support.
+    This class handles Range headers exactly like an HTTP
+    server would.
+    """
+    def open_local_file(self, req):
+        import mimetypes
+        import mimetools
+        host = req.get_host()
+        file = req.get_selector()
+        localfile = urllib.url2pathname(file)
+        stats = os.stat(localfile)
+        size = stats[stat.ST_SIZE]
+        modified = rfc822.formatdate(stats[stat.ST_MTIME])
+        mtype = mimetypes.guess_type(file)[0]
+        if host:
+            host, port = urllib.splitport(host)
+            if port or socket.gethostbyname(host) not in self.get_names():
+                raise URLError('file not on local host')
+        fo = open(localfile,'rb')
+        brange = req.headers.get('Range',None)
+        brange = range_header_to_tuple(brange)
+        assert brange != ()
+        if brange:
+            (fb,lb) = brange
+            if lb == '': lb = size
+            if fb < 0 or fb > size or lb > size:
+                raise RangeError('Requested Range Not Satisfiable')
+            size = (lb - fb)
+            fo = RangeableFileObject(fo, (fb,lb))
+        headers = mimetools.Message(StringIO(
+            'Content-Type: %s\nContent-Length: %d\nLast-modified: %s\n' %
+            (mtype or 'text/plain', size, modified)))
+        return urllib.addinfourl(fo, headers, 'file:'+file)
+
+
+# FTP Range Support 
+# Unfortunately, a large amount of base FTP code had to be copied
+# from urllib and urllib2 in order to insert the FTP REST command.
+# Code modifications for range support have been commented as 
+# follows:
+# -- range support modifications start/end here
+
+from urllib import splitport, splituser, splitpasswd, splitattr, \
+                   unquote, addclosehook, addinfourl
+import ftplib
+import socket
+import sys
+import ftplib
+import mimetypes
+import mimetools
+
+class FTPRangeHandler(urllib2.FTPHandler):
+    def ftp_open(self, req):
+        host = req.get_host()
+        if not host:
+            raise IOError, ('ftp error', 'no host given')
+        host, port = splitport(host)
+        if port is None:
+            port = ftplib.FTP_PORT
+
+        # username/password handling
+        user, host = splituser(host)
+        if user:
+            user, passwd = splitpasswd(user)
+        else:
+            passwd = None
+        host = unquote(host)
+        user = unquote(user or '')
+        passwd = unquote(passwd or '')
+        
+        try:
+            host = socket.gethostbyname(host)
+        except socket.error, msg:
+            raise URLError(msg)
+        path, attrs = splitattr(req.get_selector())
+        dirs = path.split('/')
+        dirs = map(unquote, dirs)
+        dirs, file = dirs[:-1], dirs[-1]
+        if dirs and not dirs[0]:
+            dirs = dirs[1:]
+        try:
+            fw = self.connect_ftp(user, passwd, host, port, dirs)
+            type = file and 'I' or 'D'
+            for attr in attrs:
+                attr, value = splitattr(attr)
+                if attr.lower() == 'type' and \
+                   value in ('a', 'A', 'i', 'I', 'd', 'D'):
+                    type = value.upper()
+            
+            # -- range support modifications start here
+            rest = None
+            range_tup = range_header_to_tuple(req.headers.get('Range',None))    
+            assert range_tup != ()
+            if range_tup:
+                (fb,lb) = range_tup
+                if fb > 0: rest = fb
+            # -- range support modifications end here
+            
+            fp, retrlen = fw.retrfile(file, type, rest)
+            
+            # -- range support modifications start here
+            if range_tup:
+                (fb,lb) = range_tup
+                if lb == '': 
+                    if retrlen is None or retrlen == 0:
+                        raise RangeError('Requested Range Not Satisfiable due to unobtainable file length.')
+                    lb = retrlen
+                    retrlen = lb - fb
+                    if retrlen < 0:
+                        # beginning of range is larger than file
+                        raise RangeError('Requested Range Not Satisfiable')
+                else:
+                    retrlen = lb - fb
+                    fp = RangeableFileObject(fp, (0,retrlen))
+            # -- range support modifications end here
+            
+            headers = ""
+            mtype = mimetypes.guess_type(req.get_full_url())[0]
+            if mtype:
+                headers += "Content-Type: %s\n" % mtype
+            if retrlen is not None and retrlen >= 0:
+                headers += "Content-Length: %d\n" % retrlen
+            sf = StringIO(headers)
+            headers = mimetools.Message(sf)
+            return addinfourl(fp, headers, req.get_full_url())
+        except ftplib.all_errors, msg:
+            raise IOError, ('ftp error', msg), sys.exc_info()[2]
+
+    def connect_ftp(self, user, passwd, host, port, dirs):
+        fw = ftpwrapper(user, passwd, host, port, dirs)
+        return fw
+
+class ftpwrapper(urllib.ftpwrapper):
+    # range support note:
+    # this ftpwrapper code is copied directly from
+    # urllib. The only enhancement is to add the rest
+    # argument and pass it on to ftp.ntransfercmd
+    def retrfile(self, file, type, rest=None):
+        self.endtransfer()
+        if type in ('d', 'D'): cmd = 'TYPE A'; isdir = 1
+        else: cmd = 'TYPE ' + type; isdir = 0
+        try:
+            self.ftp.voidcmd(cmd)
+        except ftplib.all_errors:
+            self.init()
+            self.ftp.voidcmd(cmd)
+        conn = None
+        if file and not isdir:
+            # Use nlst to see if the file exists at all
+            try:
+                self.ftp.nlst(file)
+            except ftplib.error_perm, reason:
+                raise IOError, ('ftp error', reason), sys.exc_info()[2]
+            # Restore the transfer mode!
+            self.ftp.voidcmd(cmd)
+            # Try to retrieve as a file
+            try:
+                cmd = 'RETR ' + file
+                conn = self.ftp.ntransfercmd(cmd, rest)
+            except ftplib.error_perm, reason:
+                if str(reason)[:3] == '501':
+                    # workaround for REST not supported error
+                    fp, retrlen = self.retrfile(file, type)
+                    fp = RangeableFileObject(fp, (rest,''))
+                    return (fp, retrlen)
+                elif str(reason)[:3] != '550':
+                    raise IOError, ('ftp error', reason), sys.exc_info()[2]
+        if not conn:
+            # Set transfer mode to ASCII!
+            self.ftp.voidcmd('TYPE A')
+            # Try a directory listing
+            if file: cmd = 'LIST ' + file
+            else: cmd = 'LIST'
+            conn = self.ftp.ntransfercmd(cmd)
+        self.busy = 1
+        # Pass back both a suitably decorated object and a retrieval length
+        return (addclosehook(conn[0].makefile('rb'),
+                            self.endtransfer), conn[1])
+
+
+####################################################################
+# Range Tuple Functions
+# XXX: These range tuple functions might go better in a class.
+
+_rangere = None
+def range_header_to_tuple(range_header):
+    """Get a (firstbyte,lastbyte) tuple from a Range header value.
+    
+    Range headers have the form "bytes=<firstbyte>-<lastbyte>". This
+    function pulls the firstbyte and lastbyte values and returns
+    a (firstbyte,lastbyte) tuple. If lastbyte is not specified in
+    the header value, it is returned as an empty string in the
+    tuple.
+    
+    Return None if range_header is None
+    Return () if range_header does not conform to the range spec 
+    pattern.
+    
+    """
+    global _rangere
+    if range_header is None: return None
+    if _rangere is None:
+        import re
+        _rangere = re.compile(r'^bytes=(\d{1,})-(\d*)')
+    match = _rangere.match(range_header)
+    if match: 
+        tup = range_tuple_normalize(match.group(1,2))
+        if tup and tup[1]: 
+            tup = (tup[0],tup[1]+1)
+        return tup
+    return ()
+
+def range_tuple_to_header(range_tup):
+    """Convert a range tuple to a Range header value.
+    Return a string of the form "bytes=<firstbyte>-<lastbyte>" or None
+    if no range is needed.
+    """
+    if range_tup is None: return None
+    range_tup = range_tuple_normalize(range_tup)
+    if range_tup:
+        if range_tup[1]: 
+            range_tup = (range_tup[0],range_tup[1] - 1)
+        return 'bytes=%s-%s' % range_tup
+    
+def range_tuple_normalize(range_tup):
+    """Normalize a (first_byte,last_byte) range tuple.
+    Return a tuple whose first element is guaranteed to be an int
+    and whose second element will be '' (meaning: the last byte) or 
+    an int. Finally, return None if the normalized tuple == (0,'')
+    as that is equivelant to retrieving the entire file.
+    """
+    if range_tup is None: return None
+    # handle first byte
+    fb = range_tup[0]
+    if fb in (None,''): fb = 0
+    else: fb = int(fb)
+    # handle last byte
+    try: lb = range_tup[1]
+    except IndexError: lb = ''
+    else:  
+        if lb is None: lb = ''
+        elif lb != '': lb = int(lb)
+    # check if range is over the entire file
+    if (fb,lb) == (0,''): return None
+    # check that the range is valid
+    if lb < fb: raise RangeError('Invalid byte range: %s-%s' % (fb,lb))
+    return (fb,lb)
+