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python-uncompyle6/uncompyle6/scanners/scanner26.py
rocky 597d51951e Improve Python 2.6 & 2.7 verification
2017-01-23 02:32:09 -05:00

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# Copyright (c) 2015, 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 2.6 bytecode scanner
This overlaps Python's 2.6'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.
"""
import sys
from uncompyle6 import PYTHON3
if PYTHON3:
intern = sys.intern
import uncompyle6.scanners.scanner2 as scan
# bytecode verification, verify(), uses JUMP_OPs from here
from xdis.opcodes import opcode_26
JUMP_OPs = opcode_26.JUMP_OPs
class Scanner26(scan.Scanner2):
def __init__(self, show_asm=False):
super(Scanner26, self).__init__(2.6, show_asm)
self.stmt_opcodes = frozenset([
self.opc.SETUP_LOOP, self.opc.BREAK_LOOP,
self.opc.SETUP_FINALLY, self.opc.END_FINALLY,
self.opc.SETUP_EXCEPT, self.opc.POP_BLOCK,
self.opc.STORE_FAST, self.opc.DELETE_FAST,
self.opc.STORE_DEREF, self.opc.STORE_GLOBAL,
self.opc.DELETE_GLOBAL, self.opc.STORE_NAME,
self.opc.DELETE_NAME, self.opc.STORE_ATTR,
self.opc.DELETE_ATTR, self.opc.STORE_SUBSCR,
self.opc.DELETE_SUBSCR, self.opc.RETURN_VALUE,
self.opc.RAISE_VARARGS, self.opc.POP_TOP,
self.opc.PRINT_EXPR, self.opc.PRINT_ITEM,
self.opc.PRINT_NEWLINE, self.opc.PRINT_ITEM_TO,
self.opc.PRINT_NEWLINE_TO, self.opc.CONTINUE_LOOP,
self.opc.JUMP_ABSOLUTE, self.opc.EXEC_STMT,
])
# "setup" opcodes
self.setup_ops = frozenset([
self.opc.SETUP_EXCEPT, self.opc.SETUP_FINALLY,
])
# opcodes with expect a variable number pushed values whose
# count is in the opcode. For parsing we generally change the
# opcode name to include that number.
self.varargs_ops = frozenset([
self.opc.BUILD_LIST, self.opc.BUILD_TUPLE,
self.opc.BUILD_SLICE, self.opc.UNPACK_SEQUENCE,
self.opc.MAKE_FUNCTION, self.opc.CALL_FUNCTION,
self.opc.MAKE_CLOSURE, self.opc.CALL_FUNCTION_VAR,
self.opc.CALL_FUNCTION_KW, self.opc.CALL_FUNCTION_VAR_KW,
self.opc.DUP_TOPX, self.opc.RAISE_VARARGS])
# opcodes that store values into a variable
self.designator_ops = frozenset([
self.opc.STORE_FAST, self.opc.STORE_NAME,
self.opc.STORE_GLOBAL, self.opc.STORE_DEREF, self.opc.STORE_ATTR,
self.opc.STORE_SLICE_0, self.opc.STORE_SLICE_1, self.opc.STORE_SLICE_2,
self.opc.STORE_SLICE_3, self.opc.STORE_SUBSCR, self.opc.UNPACK_SEQUENCE,
self.opc.JUMP_ABSOLUTE
])
# Python 2.7 has POP_JUMP_IF_{TRUE,FALSE}_OR_POP but < 2.7 doesn't
# Add an empty set make processing more uniform.
self.pop_jump_if_or_pop = frozenset([])
return
def ingest(self, co, classname=None, code_objects={}, show_asm=None):
"""
Pick out tokens from an uncompyle6 code object, and transform them,
returning a list of uncompyle6 'Token's.
The transformations are made to assist the deparsing grammar.
Specificially:
- various types of LOAD_CONST's are categorized in terms of what they load
- COME_FROM instructions are added to assist parsing control structures
- MAKE_FUNCTION and FUNCTION_CALLS append the number of positional arguments
Also, when we encounter certain tokens, we add them to a set which will cause custom
grammar rules. Specifically, variable arg tokens like MAKE_FUNCTION or BUILD_LIST
cause specific rules for the specific number of arguments they take.
"""
show_asm = self.show_asm if not show_asm else show_asm
# show_asm = 'after'
if 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 = {}
if self.is_pypy:
customize['PyPy'] = 1
Token = self.Token # shortcut
codelen = self.setup_code(co)
self.build_lines_data(co, codelen)
self.build_prev_op(codelen)
free, names, varnames = self.unmangle_code_names(co, classname)
self.names = names
# Scan for assertions. Later we will
# turn 'LOAD_GLOBAL' to 'LOAD_ASSERT'.
# 'LOAD_ASSERT' is used in assert statements.
self.load_asserts = set()
for i in self.op_range(0, codelen):
# We need to detect the difference between:
# raise AssertionError
# and
# assert ...
if (self.code[i] == self.opc.JUMP_IF_TRUE and
i + 4 < codelen and
self.code[i+3] == self.opc.POP_TOP and
self.code[i+4] == self.opc.LOAD_GLOBAL):
if names[self.get_argument(i+4)] == 'AssertionError':
self.load_asserts.add(i+4)
jump_targets = self.find_jump_targets(show_asm)
# contains (code, [addrRefToCode])
last_stmt = self.next_stmt[0]
i = self.next_stmt[last_stmt]
replace = {}
while i < codelen - 1:
if self.lines[last_stmt].next > i:
# Distinguish "print ..." from "print ...,"
if self.code[last_stmt] == self.opc.PRINT_ITEM:
if self.code[i] == self.opc.PRINT_ITEM:
replace[i] = 'PRINT_ITEM_CONT'
elif self.code[i] == self.opc.PRINT_NEWLINE:
replace[i] = 'PRINT_NEWLINE_CONT'
last_stmt = i
i = self.next_stmt[i]
extended_arg = 0
for offset in self.op_range(0, codelen):
op = self.code[offset]
op_name = self.opname[op]
oparg = None; pattr = None
if offset in jump_targets:
jump_idx = 0
# We want to process COME_FROMs to the same offset to be in *descending*
# offset order so we have the larger range or biggest instruction interval
# last. (I think they are sorted in increasing order, but for safety
# we sort them). That way, specific COME_FROM tags will match up
# properly. For example, a "loop" with an "if" nested in it should have the
# "loop" tag last so the grammar rule matches that properly.
last_jump_offset = -1
for jump_offset in sorted(jump_targets[offset], reverse=True):
if jump_offset != last_jump_offset:
tokens.append(Token(
'COME_FROM', None, repr(jump_offset),
offset="%s_%d" % (offset, jump_idx),
has_arg = True))
jump_idx += 1
last_jump_offset = jump_offset
elif offset in self.thens:
tokens.append(Token(
'THEN', None, self.thens[offset],
offset="%s_0" % offset,
has_arg = True))
has_arg = (op >= self.opc.HAVE_ARGUMENT)
if has_arg:
oparg = self.get_argument(offset) + extended_arg
extended_arg = 0
if op == self.opc.EXTENDED_ARG:
raise NotImplementedError
extended_arg = oparg * scan.L65536
continue
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
if const.co_name == '<lambda>':
assert op_name == 'LOAD_CONST'
op_name = 'LOAD_LAMBDA'
elif const.co_name == self.genexpr_name:
op_name = 'LOAD_GENEXPR'
elif const.co_name == '<dictcomp>':
op_name = 'LOAD_DICTCOMP'
elif const.co_name == '<setcomp>':
op_name = 'LOAD_SETCOMP'
# 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 = names[oparg]
elif op in self.opc.hasjrel:
pattr = repr(offset + 3 + oparg)
if op == self.opc.JUMP_FORWARD:
target = self.get_target(offset)
# FIXME: this is a hack to catch stuff like:
# if x: continue
# the "continue" is not on a new line.
if len(tokens) and tokens[-1].type == 'JUMP_BACK':
tokens[-1].type = intern('CONTINUE')
elif op in self.opc.hasjabs:
pattr = repr(oparg)
elif op in self.opc.haslocal:
pattr = varnames[oparg]
elif op in self.opc.hascompare:
pattr = self.opc.cmp_op[oparg]
elif op in self.opc.hasfree:
pattr = free[oparg]
if op in self.varargs_ops:
# CE - Hack for >= 2.5
# Now all values loaded via LOAD_CLOSURE are packed into
# a tuple before calling MAKE_CLOSURE.
if (self.version >= 2.5 and op == self.opc.BUILD_TUPLE and
self.code[self.prev[offset]] == self.opc.LOAD_CLOSURE):
continue
else:
op_name = '%s_%d' % (op_name, oparg)
if op != self.opc.BUILD_SLICE:
customize[op_name] = oparg
elif op == self.opc.JUMP_ABSOLUTE:
# Further classify JUMP_ABSOLUTE into backward jumps
# which are used in loops, and "CONTINUE" jumps which
# may appear in a "continue" statement. The loop-type
# and continue-type jumps will help us classify loop
# boundaries The continue-type jumps help us get
# "continue" statements with would otherwise be turned
# into a "pass" statement because JUMPs are sometimes
# ignored in rules as just boundary overhead. In
# comprehensions we might sometimes classify JUMP_BACK
# as CONTINUE, but that's okay since we add a grammar
# rule for that.
target = self.get_target(offset)
if target <= offset:
op_name = 'JUMP_BACK'
if (offset in self.stmts
and self.code[offset+3] not in (self.opc.END_FINALLY,
self.opc.POP_BLOCK)):
if ((offset in self.linestartoffsets and
tokens[-1].type == 'JUMP_BACK')
or offset not in self.not_continue):
op_name = 'CONTINUE'
else:
# FIXME: this is a hack to catch stuff like:
# if x: continue
# the "continue" is not on a new line.
if tokens[-1].type == 'JUMP_BACK':
# We need 'intern' since we have
# already have processed the previous
# token.
tokens[-1].type = intern('CONTINUE')
elif op == self.opc.LOAD_GLOBAL:
if offset in self.load_asserts:
op_name = 'LOAD_ASSERT'
elif op == self.opc.RETURN_VALUE:
if offset in self.return_end_ifs:
op_name = 'RETURN_END_IF'
if offset in self.linestartoffsets:
linestart = self.linestartoffsets[offset]
else:
linestart = None
if offset not in replace:
tokens.append(Token(
op_name, oparg, pattr, offset, linestart, op,
has_arg, self.opc))
else:
tokens.append(Token(
replace[offset], oparg, pattr, offset, linestart, op,
has_arg, self.opc))
pass
pass
if show_asm in ('both', 'after'):
for t in tokens:
print(t.format(line_prefix='L.'))
print()
return tokens, customize
if __name__ == "__main__":
from uncompyle6 import PYTHON_VERSION
if PYTHON_VERSION == 2.6:
import inspect
co = inspect.currentframe().f_code
tokens, customize = Scanner26(show_asm=True).ingest(co)
else:
print("Need to be Python 2.6 to demo; I am %s." %
PYTHON_VERSION)
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