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# Copyright (C) 2007,2009 Canonical Ltd
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
"""Pyrex implementation for bencode coder/decoder"""
cdef extern from "stddef.h":
ctypedef unsigned int size_t
cdef extern from "Python.h":
ctypedef int Py_ssize_t
int PyInt_CheckExact(object o)
int PyLong_CheckExact(object o)
int PyString_CheckExact(object o)
int PyTuple_CheckExact(object o)
int PyList_CheckExact(object o)
int PyDict_CheckExact(object o)
int PyBool_Check(object o)
object PyString_FromStringAndSize(char *v, Py_ssize_t len)
char *PyString_AS_STRING(object o) except NULL
Py_ssize_t PyString_GET_SIZE(object o) except -1
object PyInt_FromString(char *str, char **pend, int base)
int Py_GetRecursionLimit()
int Py_EnterRecursiveCall(char *)
void Py_LeaveRecursiveCall()
int PyList_Append(object, object) except -1
cdef extern from "stdlib.h":
void free(void *memblock)
void *malloc(size_t size)
void *realloc(void *memblock, size_t size)
long strtol(char *, char **, int)
cdef extern from "string.h":
void *memcpy(void *dest, void *src, size_t count)
cdef extern from "python-compat.h":
int snprintf(char* buffer, size_t nsize, char* fmt, ...)
cdef class Coder:
"""Base class for both Decoder and Encoder"""
cdef readonly char *tail
cdef readonly int size
cdef extern from "_bencode_pyx.h":
void UPDATE_TAIL(Coder, int n)
int MAX_INT_AS_STR
cdef class Decoder(Coder):
"""Bencode decoder"""
cdef readonly int _yield_tuples
cdef object text
def __init__(self, s, yield_tuples=0):
"""Initialize decoder engine.
@param s: Python string.
"""
if not PyString_CheckExact(s):
raise TypeError("String required")
self.text = s
self.tail = PyString_AS_STRING(s)
self.size = PyString_GET_SIZE(s)
self._yield_tuples = int(yield_tuples)
def decode(self):
result = self._decode_object()
if self.size != 0:
raise ValueError('junk in stream')
return result
def decode_object(self):
return self._decode_object()
cdef object _decode_object(self):
cdef char ch
if 0 == self.size:
raise ValueError('stream underflow')
if Py_EnterRecursiveCall("_decode_object"):
raise RuntimeError("too deeply nested")
try:
ch = self.tail[0]
if ch == c'i':
UPDATE_TAIL(self, 1)
return self._decode_int()
elif c'0' <= ch <= c'9':
return self._decode_string()
elif ch == c'l':
UPDATE_TAIL(self, 1)
return self._decode_list()
elif ch == c'd':
UPDATE_TAIL(self, 1)
return self._decode_dict()
else:
raise ValueError('unknown object type identifier %r' % ch)
finally:
Py_LeaveRecursiveCall()
cdef void _update_tail(self, int n):
"""Update tail pointer and resulting size by n characters"""
self.size = self.size - n
self.tail = self.tail + n
cdef int _read_digits(self, char stop_char) except -1:
cdef int i
i = 0
while ((self.tail[i] >= c'0' and self.tail[i] <= c'9') or
self.tail[i] == c'-') and i < self.size:
i = i + 1
if self.tail[i] != stop_char:
raise ValueError("Stop character %c not found: %c" %
(stop_char, self.tail[i]))
if (self.tail[0] == c'0' or
(self.tail[0] == c'-' and self.tail[1] == c'0')):
if i == 1:
return i
else:
raise ValueError # leading zeroes are not allowed
return i
cdef object _decode_int(self):
cdef int i
i = self._read_digits(c'e')
self.tail[i] = 0
try:
ret = PyInt_FromString(self.tail, NULL, 10)
finally:
self.tail[i] = c'e'
UPDATE_TAIL(self, i+1)
return ret
cdef object _decode_string(self):
cdef int n, i
i = self._read_digits(c':')
n = strtol(self.tail, NULL, 10)
UPDATE_TAIL(self, i+1)
if n == 0:
return ''
if n > self.size:
raise ValueError('stream underflow')
if n < 0:
raise ValueError('string size below zero: %d' % n)
result = PyString_FromStringAndSize(self.tail, n)
UPDATE_TAIL(self, n)
return result
cdef object _decode_list(self):
result = []
while self.size > 0:
if self.tail[0] == c'e':
UPDATE_TAIL(self, 1)
if self._yield_tuples:
return tuple(result)
else:
return result
else:
PyList_Append(result, self._decode_object())
raise ValueError('malformed list')
cdef object _decode_dict(self):
cdef char ch
result = {}
lastkey = None
while self.size > 0:
ch = self.tail[0]
if ch == c'e':
UPDATE_TAIL(self, 1)
return result
else:
# keys should be strings only
key = self._decode_string()
if lastkey >= key:
raise ValueError('dict keys disordered')
else:
lastkey = key
value = self._decode_object()
result[key] = value
raise ValueError('malformed dict')
def bdecode(object s):
"""Decode string x to Python object"""
return Decoder(s).decode()
def bdecode_as_tuple(object s):
"""Decode string x to Python object, using tuples rather than lists."""
return Decoder(s, True).decode()
class Bencached(object):
__slots__ = ['bencoded']
def __init__(self, s):
self.bencoded = s
cdef enum:
INITSIZE = 1024 # initial size for encoder buffer
INT_BUF_SIZE = 32
cdef class Encoder(Coder):
"""Bencode encoder"""
cdef readonly char *buffer
cdef readonly int maxsize
def __init__(self, int maxsize=INITSIZE):
"""Initialize encoder engine
@param maxsize: initial size of internal char buffer
"""
cdef char *p
self.maxsize = 0
self.size = 0
self.tail = NULL
p = <char*>malloc(maxsize)
if p == NULL:
raise MemoryError('Not enough memory to allocate buffer '
'for encoder')
self.buffer = p
self.maxsize = maxsize
self.tail = p
def __del__(self):
free(self.buffer)
self.buffer = NULL
self.maxsize = 0
def __str__(self):
if self.buffer != NULL and self.size != 0:
return PyString_FromStringAndSize(self.buffer, self.size)
else:
return ''
cdef int _ensure_buffer(self, int required) except 0:
"""Ensure that tail of CharTail buffer has enough size.
If buffer is not big enough then function try to
realloc buffer.
"""
cdef char *new_buffer
cdef int new_size
if self.size + required < self.maxsize:
return 1
new_size = self.maxsize
while new_size < self.size + required:
new_size = new_size * 2
new_buffer = <char*>realloc(self.buffer, <size_t>new_size)
if new_buffer == NULL:
raise MemoryError('Cannot realloc buffer for encoder')
self.buffer = new_buffer
self.maxsize = new_size
self.tail = &new_buffer[self.size]
return 1
cdef void _update_tail(self, int n):
"""Update tail pointer and resulting size by n characters"""
self.size = self.size + n
self.tail = &self.tail[n]
cdef int _encode_int(self, int x) except 0:
"""Encode int to bencode string iNNNe
@param x: value to encode
"""
cdef int n
self._ensure_buffer(INT_BUF_SIZE)
n = snprintf(self.tail, INT_BUF_SIZE, "i%de", x)
if n < 0:
raise MemoryError('int %d too big to encode' % x)
UPDATE_TAIL(self, n)
return 1
cdef int _encode_long(self, x) except 0:
return self._append_string(''.join(('i', str(x), 'e')))
cdef int _append_string(self, s) except 0:
self._ensure_buffer(PyString_GET_SIZE(s))
memcpy(self.tail, PyString_AS_STRING(s), PyString_GET_SIZE(s))
UPDATE_TAIL(self, PyString_GET_SIZE(s))
return 1
cdef int _encode_string(self, x) except 0:
cdef int n
self._ensure_buffer(PyString_GET_SIZE(x) + INT_BUF_SIZE)
n = snprintf(self.tail, INT_BUF_SIZE, '%d:', PyString_GET_SIZE(x))
if n < 0:
raise MemoryError('string %s too big to encode' % x)
memcpy(<void *>(self.tail+n), PyString_AS_STRING(x),
PyString_GET_SIZE(x))
UPDATE_TAIL(self, n+PyString_GET_SIZE(x))
return 1
cdef int _encode_list(self, x) except 0:
self._ensure_buffer(2)
self.tail[0] = c'l'
UPDATE_TAIL(self, 1)
for i in x:
self.process(i)
self.tail[0] = c'e'
UPDATE_TAIL(self, 1)
return 1
cdef int _encode_dict(self, x) except 0:
self._ensure_buffer(2)
self.tail[0] = c'd'
UPDATE_TAIL(self, 1)
keys = x.keys()
keys.sort()
for k in keys:
if not PyString_CheckExact(k):
raise TypeError('key in dict should be string')
self._encode_string(k)
self.process(x[k])
self.tail[0] = c'e'
UPDATE_TAIL(self, 1)
return 1
def process(self, object x):
if Py_EnterRecursiveCall("encode"):
raise RuntimeError("too deeply nested")
try:
if PyString_CheckExact(x):
self._encode_string(x)
elif PyInt_CheckExact(x):
self._encode_int(x)
elif PyLong_CheckExact(x):
self._encode_long(x)
elif PyList_CheckExact(x) or PyTuple_CheckExact(x):
self._encode_list(x)
elif PyDict_CheckExact(x):
self._encode_dict(x)
elif PyBool_Check(x):
self._encode_int(int(x))
elif isinstance(x, Bencached):
self._append_string(x.bencoded)
else:
raise TypeError('unsupported type %r' % x)
finally:
Py_LeaveRecursiveCall()
def bencode(x):
"""Encode Python object x to string"""
encoder = Encoder()
encoder.process(x)
return str(encoder)
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