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python-uncompyle6/uncompyle6/scanners/scanner23.py
rocky ebcb1d08f4 Limited support for Python 2.3
2016-06-03 10:20:52 -04:00

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# Copyright (c) 2016 by Rocky Bernstein
# Copyright (c) 2005 by Dan Pascu <dan@windowmaker.org>
# Copyright (c) 2000-2002 by hartmut Goebel <h.goebel@crazy-compilers.com>
"""
Python 2.3 bytecode scanner
This overlaps Python's 2.3's dis module, but it can be run from Python 3 and
other versions of Python. Also, we save token information for later
use in deparsing.
"""
from uncompyle6.scanners.scanner2 import Scanner2
class Scanner23(Scanner2):
def __init__(self, show_asm=None):
super(Scanner23, self).__init__(2.3, show_asm)
def disassemble(self, co, code_objects={}, show_asm=None):
"""
Disassemble a code object, returning a list of 'Token'.
The main part of this procedure is modelled after
dis.disassemble().
"""
if self.show_asm in ('both', 'before'):
from xdis.bytecode import Bytecode
bytecode = Bytecode(co, self.opc)
for instr in bytecode.get_instructions(co):
print(instr._disassemble())
# Container for tokens
tokens = []
customize = {}
Token = self.Token # shortcut
self.code = co.co_code
structures = self.find_structures(self.code)
#cf = self.find_jump_targets(code)
n = len(self.code)
i = 0
extended_arg = 0
free = None
while i < n:
offset = i
if structures.has_key(offset):
j = 0
for elem in structures[offset]:
tokens.append(Token(elem, offset="%s_%d" % (offset, j)))
j += 1
c = self.code[i]
op = ord(c)
opname = self.opc.opname[op]
i += 1
oparg = None; pattr = None
if op >= self.opc.HAVE_ARGUMENT:
oparg = ord(self.code[i]) + ord(self.code[i+1]) * 256 + extended_arg
extended_arg = 0
i += 2
if op == self.opc.EXTENDED_ARG:
extended_arg = oparg * 65536L
if op in self.opc.hasconst:
const = co.co_consts[oparg]
# We can't use inspect.iscode() because we may be
# using a different version of Python than the
# one that this was byte-compiled on. So the code
# types may mismatch.
if hasattr(const, 'co_name'):
oparg = const
const = oparg
if const.co_name == '<lambda>':
assert opname == 'LOAD_CONST'
opname = 'LOAD_LAMBDA'
# verify uses 'pattr' for comparison, since 'attr'
# now holds Code(const) and thus can not be used
# for comparison (todo: think about changing this)
# pattr = 'code_object @ 0x%x %s->%s' %\
# (id(const), const.co_filename, const.co_name)
pattr = '<code_object ' + const.co_name + '>'
else:
pattr = const
elif op in self.opc.hasname:
pattr = co.co_names[oparg]
elif op in self.opc.hasjrel:
pattr = repr(i + oparg)
elif op in self.opc.hasjabs:
pattr = repr(oparg)
elif op in self.opc.haslocal:
pattr = co.co_varnames[oparg]
elif op in self.opc.hascompare:
pattr = self.opc.cmp_op[oparg]
elif op in self.opc.hasfree:
if free is None:
free = co.co_cellvars + co.co_freevars
pattr = free[oparg]
if opname == 'SET_LINENO':
continue
elif opname in ('BUILD_LIST', 'BUILD_TUPLE', 'BUILD_SLICE',
'UNPACK_LIST', 'UNPACK_TUPLE', 'UNPACK_SEQUENCE',
'MAKE_FUNCTION', 'CALL_FUNCTION', 'MAKE_CLOSURE',
'CALL_FUNCTION_VAR', 'CALL_FUNCTION_KW',
'CALL_FUNCTION_VAR_KW', 'DUP_TOPX',
):
opname = '%s_%d' % (opname, oparg)
customize[opname] = oparg
tokens.append(Token(opname, oparg, pattr, offset))
pass
if self.show_asm:
for t in tokens:
print(t)
print()
return tokens, customize
def __get_target(self, code, pos, op=None):
if op is None:
op = ord(code[pos])
target = ord(code[pos+1]) + ord(code[pos+2]) * 256
if op in self.self.opc.hasjrel:
target += pos + 3
return target
def __first_instr(self, code, start, end, instr, target=None, exact=True):
"""
Find the first <instr> in the block from start to end.
<instr> is any python bytecode instruction or a list of opcodes
If <instr> is an opcode with a target (like a jump), a target
destination can be specified which must match precisely if exact
is True, or if exact is False, the instruction which has a target
closest to <target> will be returned.
Return index to it or None if not found.
"""
assert(start>=0 and end<len(code))
HAVE_ARGUMENT = self.self.opc.HAVE_ARGUMENT
try: instr[0]
except: instr = [instr]
pos = None
distance = len(code)
i = start
while i < end:
op = ord(code[i])
if op in instr:
if target is None:
return i
dest = self.__get_target(code, i, op)
if dest == target:
return i
elif not exact:
_distance = abs(target - dest)
if _distance < distance:
distance = _distance
pos = i
if op < HAVE_ARGUMENT:
i += 1
else:
i += 3
return pos
def __last_instr(self, code, start, end, instr, target=None, exact=True):
"""
Find the last <instr> in the block from start to end.
<instr> is any python bytecode instruction or a list of opcodes
If <instr> is an opcode with a target (like a jump), a target
destination can be specified which must match precisely if exact
is True, or if exact is False, the instruction which has a target
closest to <target> will be returned.
Return index to it or None if not found.
"""
assert(start>=0 and end<len(code))
HAVE_ARGUMENT = self.self.opc.HAVE_ARGUMENT
try: instr[0]
except: instr = [instr]
pos = None
distance = len(code)
i = start
while i < end:
op = ord(code[i])
if op in instr:
if target is None:
pos = i
else:
dest = self.__get_target(code, i, op)
if dest == target:
distance = 0
pos = i
elif not exact:
_distance = abs(target - dest)
if _distance <= distance:
distance = _distance
pos = i
if op < HAVE_ARGUMENT:
i += 1
else:
i += 3
return pos
def __all_instr(self, code, start, end, instr, target=None):
"""
Find all <instr> in the block from start to end.
<instr> is any python bytecode instruction or a list of opcodes
If <instr> is an opcode with a target (like a jump), a target
destination can be specified which must match precisely.
Return a list with indexes to them or [] if none found.
"""
assert(start>=0 and end<len(code))
HAVE_ARGUMENT = self.self.opc.HAVE_ARGUMENT
try: instr[0]
except: instr = [instr]
result = []
i = start
while i < end:
op = ord(code[i])
if op in instr:
if target is None:
result.append(i)
elif target == self.__get_target(code, i, op):
result.append(i)
if op < HAVE_ARGUMENT:
i += 1
else:
i += 3
return result
def __next_except_jump(self, code, start, end, target):
"""
Return the next jump that was generated by an except SomeException:
construct in a try...except...else clause or None if not found.
"""
HAVE_ARGUMENT = self.opc.HAVE_ARGUMENT
JUMP_FORWARD = self.opc.opmap['JUMP_FORWARD']
JUMP_ABSOLUTE = self.opc.opmap['JUMP_ABSOLUTE']
END_FINALLY = self.opc.opmap['END_FINALLY']
POP_TOP = self.opc.opmap['POP_TOP']
DUP_TOP = self.opc.opmap['DUP_TOP']
try: SET_LINENO = self.opc.opmap['SET_LINENO']
except: SET_LINENO = None
lookup = [JUMP_ABSOLUTE, JUMP_FORWARD]
while start < end:
jmp = self.__first_instr(code, start, end, lookup, target)
if jmp is None:
return None
if jmp == end-3:
return jmp
ops = [None, None, None, None]
opp = [0, 0, 0, 0]
pos = 0
x = jmp+3
while x <= end and pos < 4:
op = ord(code[x])
if op == SET_LINENO:
x += 3
continue
elif op >= HAVE_ARGUMENT:
break
ops[pos] = op
opp[pos] = x
pos += 1
x += 1
if ops[0] == POP_TOP and ops[1] == END_FINALLY and opp[1] == end:
return jmp
if ops[0] == POP_TOP and ops[1] == DUP_TOP:
return jmp
if ops[0] == ops[1] == ops[2] == ops[3] == POP_TOP:
return jmp
start = jmp + 3
return None
def __list_comprehension(self, code, pos, op=None):
"""
Determine if there is a list comprehension structure starting at pos
"""
BUILD_LIST = self.opc.opmap['BUILD_LIST']
DUP_TOP = self.opc.opmap['DUP_TOP']
LOAD_ATTR = self.opc.opmap['LOAD_ATTR']
if op is None:
op = ord(code[pos])
if op != BUILD_LIST:
return 0
try:
elems = ord(code[pos+1]) + ord(code[pos+2])*256
codes = (op, elems, ord(code[pos+3]), ord(code[pos+4]))
except IndexError:
return 0
return (codes==(BUILD_LIST, 0, DUP_TOP, LOAD_ATTR))
def __ignore_if(self, code, pos):
"""
Return true if this 'if' is to be ignored.
"""
POP_TOP = self.opc.opmap['POP_TOP']
COMPARE_OP = self.opc.opmap['COMPARE_OP']
EXCEPT_MATCH = self.opc.copmap['exception match']
## If that was added by a while loop
if pos in self.__ignored_ifs:
return 1
# Check if we can test only for POP_TOP for this -Dan
# Maybe need to be done as above (skip SET_LINENO's)
if (ord(code[pos-3])==COMPARE_OP and
(ord(code[pos-2]) + ord(code[pos-1])*256)==EXCEPT_MATCH and
ord(code[pos+3])==POP_TOP and
ord(code[pos+4])==POP_TOP and
ord(code[pos+5])==POP_TOP and
ord(code[pos+6])==POP_TOP):
return 1 ## Exception match
return 0
def __fix_parent(self, code, target, parent):
"""Fix parent boundaries if needed"""
JUMP_ABSOLUTE = self.opc.opmap['JUMP_ABSOLUTE']
start = parent['start']
end = parent['end']
## Map the second start point for 'while 1:' in python 2.3+ to start
try: target = self.__while1[target]
except: pass
if target >= start or end-start < 3 or target not in self.__loops:
return
if ord(code[end-3])==JUMP_ABSOLUTE:
cont_target = self.__get_target(code, end-3, JUMP_ABSOLUTE)
if target == cont_target:
parent['end'] = end-3
def __restrict_to_parent(self, target, parent):
"""Restrict pos to parent boundaries."""
if not (parent['start'] < target < parent['end']):
target = parent['end']
return target
def __detect_structure(self, code, pos, op=None):
"""
Detect structures and their boundaries to fix optimizied jumps
in python2.3+
"""
# TODO: check the struct boundaries more precisely -Dan
SETUP_LOOP = self.opc.opmap['SETUP_LOOP']
FOR_ITER = self.opc.opmap['FOR_ITER']
GET_ITER = self.opc.opmap['GET_ITER']
SETUP_EXCEPT = self.opc.opmap['SETUP_EXCEPT']
JUMP_FORWARD = self.opc.opmap['JUMP_FORWARD']
JUMP_ABSOLUTE = self.opc.opmap['JUMP_ABSOLUTE']
JUMP_IF_FALSE = self.opc.opmap['JUMP_IF_FALSE']
JUMP_IF_TRUE = self.opc.opmap['JUMP_IF_TRUE']
END_FINALLY = self.opc.opmap['END_FINALLY']
POP_TOP = self.opc.opmap['POP_TOP']
POP_BLOCK = self.opc.opmap['POP_BLOCK']
try: SET_LINENO = self.opc.opmap['SET_LINENO']
except: SET_LINENO = None
# Ev remove this test and make op a mandatory argument -Dan
if op is None:
op = ord(code[pos])
## Detect parent structure
parent = self.__structs[0]
start = parent['start']
end = parent['end']
for s in self.__structs:
if s['type'] == 'LOGIC_TEST':
continue ## logic tests are not structure containers
_start = s['start']
_end = s['end']
if (_start <= pos < _end) and (_start >= start and _end < end):
start = _start
end = _end
parent = s
## We need to know how many new structures were added in this run
origStructCount = len(self.__structs)
if op == SETUP_LOOP:
start = pos+3
# this is for python2.2. Maybe we can optimize and not call this for 2.3+ -Dan
while ord(code[start]) == SET_LINENO:
start += 3
start_op = ord(code[start])
while1 = False
if start_op in (JUMP_FORWARD, JUMP_ABSOLUTE):
## This is a while 1 (has a particular structure)
start = self.__get_target(code, start, start_op)
start = self.__restrict_to_parent(start, parent)
self.__while1[pos+3] = start ## map between the 2 start points
while1 = True
if start_op == JUMP_ABSOLUTE and ord(code[pos+6])==JUMP_IF_FALSE:
# special `while 1: pass` in python2.3
self.__fixed_jumps[pos+3] = start
target = self.__get_target(code, pos, op)
end = self.__restrict_to_parent(target, parent)
if target != end:
self.__fixed_jumps[pos] = end
jump_back = self.__last_instr(code, start, end, JUMP_ABSOLUTE,
start, False)
assert(jump_back is not None)
target = self.__get_target(code, jump_back, JUMP_ABSOLUTE)
i = target
while i < jump_back and ord(code[i])==SET_LINENO:
i += 3
if ord(code[i]) in (FOR_ITER, GET_ITER):
loop_type = 'FOR'
else:
lookup = [JUMP_IF_FALSE, JUMP_IF_TRUE]
test = self.__first_instr(code, pos+3, jump_back, lookup, jump_back+3)
if test is None:
# this is a special while 1 structure in python 2.4
while1 = True
else:
#assert(test is not None)
test_target = self.__get_target(code, test)
test_target = self.__restrict_to_parent(test_target, parent)
next = (ord(code[test_target]), ord(code[test_target+1]))
if next == (POP_TOP, POP_BLOCK):
self.__ignored_ifs.append(test)
else:
while1 = True
if while1 == True:
loop_type = 'WHILE1'
else:
loop_type = 'WHILE'
self.__loops.append(target)
self.__structs.append({'type': loop_type,
'start': target,
'end': jump_back})
self.__structs.append({'type': loop_type + '_ELSE',
'start': jump_back+3,
'end': end})
elif self.__list_comprehension(code, pos, op):
get_iter = self.__first_instr(code, pos+7, end, GET_ITER)
for_iter = self.__first_instr(code, get_iter, end, FOR_ITER)
assert(get_iter is not None and for_iter is not None)
start = get_iter+1
target = self.__get_target(code, for_iter, FOR_ITER)
end = self.__restrict_to_parent(target, parent)
jump_back = self.__last_instr(code, start, end, JUMP_ABSOLUTE,
start, False)
assert(jump_back is not None)
target = self.__get_target(code, jump_back, JUMP_ABSOLUTE)
start = self.__restrict_to_parent(target, parent)
self.__structs.append({'type': 'LIST_COMPREHENSION',
'start': start,
'end': jump_back})
elif op == SETUP_EXCEPT:
start = pos+3
target = self.__get_target(code, pos, op)
# this should be redundant as it can't be out of boundaries -Dan
# check if it can be removed
end = self.__restrict_to_parent(target, parent)
if target != end:
#print "!!!!found except target != end: %s %s" % (target, end)
self.__fixed_jumps[pos] = end
## Add the try block
self.__structs.append({'type': 'TRY',
'start': start,
'end': end-4})
## Now isolate the except and else blocks
start = end
target = self.__get_target(code, start-3)
#self.__fix_parent(code, target, parent)
try_else_start = target
end = self.__restrict_to_parent(target, parent)
if target != end:
self.__fixed_jumps[start-3] = end
end_finally = self.__last_instr(code, start, end, END_FINALLY)
assert(end_finally is not None)
lookup = [JUMP_ABSOLUTE, JUMP_FORWARD]
jump_end = self.__last_instr(code, start, end_finally, lookup)
assert(jump_end is not None)
target = self.__get_target(code, jump_end)
if target == try_else_start:
end = end_finally+1
else:
end = self.__restrict_to_parent(target, parent)
if target != end:
self.__fixed_jumps[jump_end] = end
## Add the try-else block
self.__structs.append({'type': 'TRY_ELSE',
'start': end_finally+1,
'end': end})
## Add the except blocks
i = start
while i < end_finally:
jmp = self.__next_except_jump(code, i, end_finally, target)
if jmp is None:
break
if i!=start and ord(code[i])==POP_TOP:
pos = i + 1
else:
pos = i
self.__structs.append({'type': 'EXCEPT',
'start': pos,
'end': jmp})
if target != end:
self.__fixed_jumps[jmp] = end
i = jmp+3
elif op == JUMP_ABSOLUTE:
## detect if we have a 'foo and bar and baz...' structure
## that was optimized (thus the presence of JUMP_ABSOLUTE)
return # no longer needed. just return. remove this elif later -Dan
if pos in self.__fixed_jumps:
return ## Already marked
if parent['end'] - pos < 7:
return
next = (ord(code[pos+3]), ord(code[pos+6]))
if next != (JUMP_IF_FALSE, POP_TOP):
return
end = self.__get_target(code, pos+3)
ifs = self.__all_instr(code, pos, end, JUMP_IF_FALSE, end)
## Test if all JUMP_IF_FALSE we have found belong to the
## structure (may not be needed but it doesn't hurt)
count = len(ifs)
if count < 2:
return
for jif in ifs[1:]:
before = ord(code[jif-3])
after = ord(code[jif+3])
if (before not in (JUMP_FORWARD, JUMP_ABSOLUTE) or
after != POP_TOP):
return
## All tests passed. Perform fixes
self.__ignored_ifs.extend(ifs)
for i in range(count-1):
self.__fixed_jumps[ifs[i]-3] = ifs[i+1]-3
elif op in (JUMP_IF_FALSE, JUMP_IF_TRUE):
if self.__ignore_if(code, pos):
return
start = pos+4 ## JUMP_IF_FALSE/TRUE + POP_TOP
target = self.__get_target(code, pos, op)
if parent['start'] <= target <= parent['end']:
if ord(code[target-3]) in (JUMP_ABSOLUTE, JUMP_FORWARD):
if_end = self.__get_target(code, target-3)
#self.__fix_parent(code, if_end, parent)
end = self.__restrict_to_parent(if_end, parent)
if ord(code[end-3]) == JUMP_ABSOLUTE:
else_end = self.__get_target(code, end-3)
if if_end == else_end and if_end in self.__loops:
end -= 3 ## skip the continue instruction
if if_end != end:
self.__fixed_jumps[target-3] = end
self.__structs.append({'type': 'IF_THEN',
'start': start,
'end': target-3})
self.__structs.append({'type': 'IF_ELSE',
'start': target+1,
'end': end})
else:
self.__structs.append({'type': 'LOGIC_TEST',
'start': start,
'end': target})
def find_jump_targets(self, code):
"""
Detect all offsets in a byte code which are jump targets.
Return the list of offsets.
This procedure is modelled after self.opc.findlables(), but here
for each target the number of jumps are counted.
"""
HAVE_ARGUMENT = self.opc.HAVE_ARGUMENT
hasjrel = self.opc.hasjrel
hasjabs = self.opc.hasjabs
needFixing = (self.__pyversion >= 2.3)
n = len(code)
self.__structs = [{'type': 'root',
'start': 0,
'end': n-1}]
self.__loops = [] ## All loop entry points
self.__while1 = {} ## 'while 1:' in python 2.3+ has another start point
self.__fixed_jumps = {} ## Map fixed jumps to their real destination
self.__ignored_ifs = [] ## JUMP_IF_XXXX's we should ignore
targets = {}
i = 0
while i < n:
op = ord(code[i])
if needFixing:
## Determine structures and fix jumps for 2.3+
self.__detect_structure(code, i, op)
if op >= HAVE_ARGUMENT:
label = self.__fixed_jumps.get(i)
if label is None:
oparg = ord(code[i+1]) + ord(code[i+2]) * 256
if op in hasjrel:
label = i + 3 + oparg
elif op in hasjabs:
# todo: absolute jumps
pass
if label is not None:
targets[label] = targets.get(label, 0) + 1
i += 3
else:
i += 1
return targets
def find_structures(self, code):
"""
Detect all structures in a byte code.
Return a mapping from offset to a list of keywords that should
be inserted at that position.
"""
HAVE_ARGUMENT = self.opc.HAVE_ARGUMENT
n = len(code)
self.__structs = [{'type': 'root',
'start': 0,
'end': n-1}]
self.__loops = [] ## All loop entry points
self.__while1 = {} ## 'while 1:' in python 2.3+ has another start point
self.__fixed_jumps = {} ## Map fixed jumps to their real destination
self.__ignored_ifs = [] ## JUMP_IF_XXXX's we should ignore
i = 0
while i < n:
op = ord(code[i])
if op >= HAVE_ARGUMENT:
i += 3
else:
i += 1
#from pprint import pprint
#print
#print "structures: ",
#pprint(self.__structs)
#print "loops: ",
#pprint(self.__loops)
#print "while1: ",
#pprint(self.__while1)
#print "fixed jumps: ",
#pprint(self.__fixed_jumps)
#print "ignored ifs: ",
#pprint(self.__ignored_ifs)
#print
points = {}
endpoints = {}
for s in self.__structs:
typ = s['type']
start = s['start']
end = s['end']
if typ == 'root':
continue
## startpoints of the outer structures must come first
## endpoints of the inner structures must come first
points.setdefault(start, []).append("%s_START" % typ)
endpoints.setdefault(end, []).insert(0, "%s_END" % typ)
for k, v in endpoints.items():
points.setdefault(k, []).extend(v)
#print "points: ",
#pprint(points)
#print
return points
# __scanners = {}
# def getscanner(version):
# if not __scanners.has_key(version):
# __scanners[version] = Scanner(version)
# return __scanners[version]
if __name__ == "__main__":
from uncompyle6 import PYTHON_VERSION
if PYTHON_VERSION == 2.3:
import inspect
co = inspect.currentframe().f_code
tokens, customize = Scanner23().disassemble(co)
for t in tokens:
print(t.format())
else:
print("Need to be Python 2.3 to demo; I am %s." %
PYTHON_VERSION)
# local variables:
# tab-width: 4
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