From: Oleg Broytman Date: Fri, 22 Nov 2013 23:45:23 +0000 (+0400) Subject: Add eff_bdecode.py X-Git-Url: https://git.phdru.name/?a=commitdiff_plain;h=a9d5c6ff137cc72e2887dd193c9865e3bb9c4f94;p=extfs.d.git Add eff_bdecode.py --- diff --git a/eff_bdecode.py b/eff_bdecode.py new file mode 100644 index 0000000..5f5b93b --- /dev/null +++ b/eff_bdecode.py @@ -0,0 +1,71 @@ +# http://effbot.org/zone/bencode.htm +# http://effbot.org/zone/copyright.htm +# +# Copyright (C) 1995-2013 by Fredrik Lundh +# +# By obtaining, using, and/or copying this software and/or its associated +# documentation, you agree that you have read, understood, and will comply with +# the following terms and conditions: +# +# Permission to use, copy, modify, and distribute this software and its +# associated documentation for any purpose and without fee is hereby granted, +# provided that the above copyright notice appears in all copies, and that both +# that copyright notice and this permission notice appear in supporting +# documentation, and that the name of Secret Labs AB or the author not be used +# in advertising or publicity pertaining to distribution of the software +# without specific, written prior permission. +# +# SECRET LABS AB AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS +# SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN +# NO EVENT SHALL SECRET LABS AB OR THE AUTHOR BE LIABLE FOR ANY SPECIAL, +# INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM +# LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR +# OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR +# PERFORMANCE OF THIS SOFTWARE. + +import re + +def tokenize(text, match=re.compile("([idel])|(\d+):|(-?\d+)").match): + i = 0 + while i < len(text): + m = match(text, i) + s = m.group(m.lastindex) + i = m.end() + if m.lastindex == 2: + yield "s" + yield text[i:i+int(s)] + i = i + int(s) + else: + yield s + +def decode_item(next, token): + if token == "i": + # integer: "i" value "e" + data = int(next()) + if next() != "e": + raise ValueError + elif token == "s": + # string: "s" value (virtual tokens) + data = next() + elif token == "l" or token == "d": + # container: "l" (or "d") values "e" + data = [] + tok = next() + while tok != "e": + data.append(decode_item(next, tok)) + tok = next() + if token == "d": + data = dict(zip(data[0::2], data[1::2])) + else: + raise ValueError + return data + +def decode(text): + try: + src = tokenize(text) + data = decode_item(src.next, src.next()) + for token in src: # look for more tokens + raise SyntaxError("trailing junk") + except (AttributeError, ValueError, StopIteration): + raise SyntaxError("syntax error") + return data