Repository navigation
Expand file tree
/
Copy pathdis.py
More file actions
475 lines (418 loc) · 16.8 KB
/
Copy pathdis.py
File metadata and controls
475 lines (418 loc) · 16.8 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
"""Disassembler of Python byte code into mnemonics."""
import sys
import types
import collections
import io
from opcode import *
from opcode import __all__ as _opcodes_all
__all__ = ["code_info", "dis", "disassemble", "distb", "disco",
"findlinestarts", "findlabels", "show_code",
"get_instructions", "Instruction", "Bytecode"] + _opcodes_all
del _opcodes_all
_have_code = (types.MethodType, types.FunctionType, types.CodeType, type)
def _try_compile(source, name):
"""Attempts to compile the given source, first as an expression and
then as a statement if the first approach fails.
Utility function to accept strings in functions that otherwise
expect code objects
"""
try:
c = compile(source, name, 'eval')
except SyntaxError:
c = compile(source, name, 'exec')
return c
def dis(x=None, *, file=None):
"""Disassemble classes, methods, functions, or code.
With no argument, disassemble the last traceback.
"""
if x is None:
distb(file=file)
return
if hasattr(x, '__func__'): # Method
x = x.__func__
if hasattr(x, '__code__'): # Function
x = x.__code__
if hasattr(x, '__dict__'): # Class or module
items = sorted(x.__dict__.items())
for name, x1 in items:
if isinstance(x1, _have_code):
print("Disassembly of %s:" % name, file=file)
try:
dis(x1, file=file)
except TypeError as msg:
print("Sorry:", msg, file=file)
print(file=file)
elif hasattr(x, 'co_code'): # Code object
disassemble(x, file=file)
elif isinstance(x, (bytes, bytearray)): # Raw bytecode
_disassemble_bytes(x, file=file)
elif isinstance(x, str): # Source code
_disassemble_str(x, file=file)
else:
raise TypeError("don't know how to disassemble %s objects" %
type(x).__name__)
def distb(tb=None, *, file=None):
"""Disassemble a traceback (default: last traceback)."""
if tb is None:
try:
tb = sys.last_traceback
except AttributeError:
raise RuntimeError("no last traceback to disassemble")
while tb.tb_next: tb = tb.tb_next
disassemble(tb.tb_frame.f_code, tb.tb_lasti, file=file)
# The inspect module interrogates this dictionary to build its
# list of CO_* constants. It is also used by pretty_flags to
# turn the co_flags field into a human readable list.
COMPILER_FLAG_NAMES = {
1: "OPTIMIZED",
2: "NEWLOCALS",
4: "VARARGS",
8: "VARKEYWORDS",
16: "NESTED",
32: "GENERATOR",
64: "NOFREE",
}
def pretty_flags(flags):
"""Return pretty representation of code flags."""
names = []
for i in range(32):
flag = 1<<i
if flags & flag:
names.append(COMPILER_FLAG_NAMES.get(flag, hex(flag)))
flags ^= flag
if not flags:
break
else:
names.append(hex(flags))
return ", ".join(names)
def _get_code_object(x):
"""Helper to handle methods, functions, strings and raw code objects"""
if hasattr(x, '__func__'): # Method
x = x.__func__
if hasattr(x, '__code__'): # Function
x = x.__code__
if isinstance(x, str): # Source code
x = _try_compile(x, "<disassembly>")
if hasattr(x, 'co_code'): # Code object
return x
raise TypeError("don't know how to disassemble %s objects" %
type(x).__name__)
def code_info(x):
"""Formatted details of methods, functions, or code."""
return _format_code_info(_get_code_object(x))
def _format_code_info(co):
lines = []
lines.append("Name: %s" % co.co_name)
lines.append("Filename: %s" % co.co_filename)
lines.append("Argument count: %s" % co.co_argcount)
lines.append("Kw-only arguments: %s" % co.co_kwonlyargcount)
lines.append("Number of locals: %s" % co.co_nlocals)
lines.append("Stack size: %s" % co.co_stacksize)
lines.append("Flags: %s" % pretty_flags(co.co_flags))
if co.co_consts:
lines.append("Constants:")
for i_c in enumerate(co.co_consts):
lines.append("%4d: %r" % i_c)
if co.co_names:
lines.append("Names:")
for i_n in enumerate(co.co_names):
lines.append("%4d: %s" % i_n)
if co.co_varnames:
lines.append("Variable names:")
for i_n in enumerate(co.co_varnames):
lines.append("%4d: %s" % i_n)
if co.co_freevars:
lines.append("Free variables:")
for i_n in enumerate(co.co_freevars):
lines.append("%4d: %s" % i_n)
if co.co_cellvars:
lines.append("Cell variables:")
for i_n in enumerate(co.co_cellvars):
lines.append("%4d: %s" % i_n)
return "\n".join(lines)
def show_code(co, *, file=None):
"""Print details of methods, functions, or code to *file*.
If *file* is not provided, the output is printed on stdout.
"""
print(code_info(co), file=file)
_Instruction = collections.namedtuple("_Instruction",
"opname opcode arg argval argrepr offset starts_line is_jump_target")
class Instruction(_Instruction):
"""Details for a bytecode operation
Defined fields:
opname - human readable name for operation
opcode - numeric code for operation
arg - numeric argument to operation (if any), otherwise None
argval - resolved arg value (if known), otherwise same as arg
argrepr - human readable description of operation argument
offset - start index of operation within bytecode sequence
starts_line - line started by this opcode (if any), otherwise None
is_jump_target - True if other code jumps to here, otherwise False
"""
def _disassemble(self, lineno_width=3, mark_as_current=False):
"""Format instruction details for inclusion in disassembly output
*lineno_width* sets the width of the line number field (0 omits it)
*mark_as_current* inserts a '-->' marker arrow as part of the line
"""
fields = []
# Column: Source code line number
if lineno_width:
if self.starts_line is not None:
lineno_fmt = "%%%dd" % lineno_width
fields.append(lineno_fmt % self.starts_line)
else:
fields.append(' ' * lineno_width)
# Column: Current instruction indicator
if mark_as_current:
fields.append('-->')
else:
fields.append(' ')
# Column: Jump target marker
if self.is_jump_target:
fields.append('>>')
else:
fields.append(' ')
# Column: Instruction offset from start of code sequence
fields.append(repr(self.offset).rjust(4))
# Column: Opcode name
fields.append(self.opname.ljust(20))
# Column: Opcode argument
if self.arg is not None:
fields.append(repr(self.arg).rjust(5))
# Column: Opcode argument details
if self.argrepr:
fields.append('(' + self.argrepr + ')')
return ' '.join(fields).rstrip()
def get_instructions(x, *, first_line=None):
"""Iterator for the opcodes in methods, functions or code
Generates a series of Instruction named tuples giving the details of
each operations in the supplied code.
If *first_line* is not None, it indicates the line number that should
be reported for the first source line in the disassembled code.
Otherwise, the source line information (if any) is taken directly from
the disassembled code object.
"""
co = _get_code_object(x)
cell_names = co.co_cellvars + co.co_freevars
linestarts = dict(findlinestarts(co))
if first_line is not None:
line_offset = first_line - co.co_firstlineno
else:
line_offset = 0
return _get_instructions_bytes(co.co_code, co.co_varnames, co.co_names,
co.co_consts, cell_names, linestarts,
line_offset)
def _get_const_info(const_index, const_list):
"""Helper to get optional details about const references
Returns the dereferenced constant and its repr if the constant
list is defined.
Otherwise returns the constant index and its repr().
"""
argval = const_index
if const_list is not None:
argval = const_list[const_index]
return argval, repr(argval)
def _get_name_info(name_index, name_list):
"""Helper to get optional details about named references
Returns the dereferenced name as both value and repr if the name
list is defined.
Otherwise returns the name index and its repr().
"""
argval = name_index
if name_list is not None:
argval = name_list[name_index]
argrepr = argval
else:
argrepr = repr(argval)
return argval, argrepr
def _get_instructions_bytes(code, varnames=None, names=None, constants=None,
cells=None, linestarts=None, line_offset=0):
"""Iterate over the instructions in a bytecode string.
Generates a sequence of Instruction namedtuples giving the details of each
opcode. Additional information about the code's runtime environment
(e.g. variable names, constants) can be specified using optional
arguments.
"""
labels = findlabels(code)
extended_arg = 0
starts_line = None
free = None
# enumerate() is not an option, since we sometimes process
# multiple elements on a single pass through the loop
n = len(code)
i = 0
while i < n:
op = code[i]
offset = i
if linestarts is not None:
starts_line = linestarts.get(i, None)
if starts_line is not None:
starts_line += line_offset
is_jump_target = i in labels
i = i+1
arg = None
argval = None
argrepr = ''
if op >= HAVE_ARGUMENT:
arg = code[i] + code[i+1]*256 + extended_arg
extended_arg = 0
i = i+2
if op == EXTENDED_ARG:
extended_arg = arg*65536
# Set argval to the dereferenced value of the argument when
# availabe, and argrepr to the string representation of argval.
# _disassemble_bytes needs the string repr of the
# raw name index for LOAD_GLOBAL, LOAD_CONST, etc.
argval = arg
if op in hasconst:
argval, argrepr = _get_const_info(arg, constants)
elif op in hasname:
argval, argrepr = _get_name_info(arg, names)
elif op in hasjrel:
argval = i + arg
argrepr = "to " + repr(argval)
elif op in haslocal:
argval, argrepr = _get_name_info(arg, varnames)
elif op in hascompare:
argval = cmp_op[arg]
argrepr = argval
elif op in hasfree:
argval, argrepr = _get_name_info(arg, cells)
elif op in hasnargs:
argrepr = "%d positional, %d keyword pair" % (code[i-2], code[i-1])
yield Instruction(opname[op], op,
arg, argval, argrepr,
offset, starts_line, is_jump_target)
def disassemble(co, lasti=-1, *, file=None):
"""Disassemble a code object."""
cell_names = co.co_cellvars + co.co_freevars
linestarts = dict(findlinestarts(co))
_disassemble_bytes(co.co_code, lasti, co.co_varnames, co.co_names,
co.co_consts, cell_names, linestarts, file=file)
def _disassemble_bytes(code, lasti=-1, varnames=None, names=None,
constants=None, cells=None, linestarts=None,
*, file=None, line_offset=0):
# Omit the line number column entirely if we have no line number info
show_lineno = linestarts is not None
# TODO?: Adjust width upwards if max(linestarts.values()) >= 1000?
lineno_width = 3 if show_lineno else 0
for instr in _get_instructions_bytes(code, varnames, names,
constants, cells, linestarts,
line_offset=line_offset):
new_source_line = (show_lineno and
instr.starts_line is not None and
instr.offset > 0)
if new_source_line:
print(file=file)
is_current_instr = instr.offset == lasti
print(instr._disassemble(lineno_width, is_current_instr), file=file)
def _disassemble_str(source, *, file=None):
"""Compile the source string, then disassemble the code object."""
disassemble(_try_compile(source, '<dis>'), file=file)
disco = disassemble # XXX For backwards compatibility
def findlabels(code):
"""Detect all offsets in a byte code which are jump targets.
Return the list of offsets.
"""
labels = []
# enumerate() is not an option, since we sometimes process
# multiple elements on a single pass through the loop
n = len(code)
i = 0
while i < n:
op = code[i]
i = i+1
if op >= HAVE_ARGUMENT:
arg = code[i] + code[i+1]*256
i = i+2
label = -1
if op in hasjrel:
label = i+arg
elif op in hasjabs:
label = arg
if label >= 0:
if label not in labels:
labels.append(label)
return labels
def findlinestarts(code):
"""Find the offsets in a byte code which are start of lines in the source.
Generate pairs (offset, lineno) as described in Python/compile.c.
"""
byte_increments = list(code.co_lnotab[0::2])
line_increments = list(code.co_lnotab[1::2])
lastlineno = None
lineno = code.co_firstlineno
addr = 0
for byte_incr, line_incr in zip(byte_increments, line_increments):
if byte_incr:
if lineno != lastlineno:
yield (addr, lineno)
lastlineno = lineno
addr += byte_incr
lineno += line_incr
if lineno != lastlineno:
yield (addr, lineno)
class Bytecode:
"""The bytecode operations of a piece of code
Instantiate this with a function, method, string of code, or a code object
(as returned by compile()).
Iterating over this yields the bytecode operations as Instruction instances.
"""
def __init__(self, x, *, first_line=None, current_offset=None):
self.codeobj = co = _get_code_object(x)
if first_line is None:
self.first_line = co.co_firstlineno
self._line_offset = 0
else:
self.first_line = first_line
self._line_offset = first_line - co.co_firstlineno
self._cell_names = co.co_cellvars + co.co_freevars
self._linestarts = dict(findlinestarts(co))
self._original_object = x
self.current_offset = current_offset
def __iter__(self):
co = self.codeobj
return _get_instructions_bytes(co.co_code, co.co_varnames, co.co_names,
co.co_consts, self._cell_names,
self._linestarts,
line_offset=self._line_offset)
def __repr__(self):
return "{}({!r})".format(self.__class__.__name__,
self._original_object)
@classmethod
def from_traceback(cls, tb):
""" Construct a Bytecode from the given traceback """
while tb.tb_next:
tb = tb.tb_next
return cls(tb.tb_frame.f_code, current_offset=tb.tb_lasti)
def info(self):
"""Return formatted information about the code object."""
return _format_code_info(self.codeobj)
def dis(self):
"""Return a formatted view of the bytecode operations."""
co = self.codeobj
if self.current_offset is not None:
offset = self.current_offset
else:
offset = -1
with io.StringIO() as output:
_disassemble_bytes(co.co_code, varnames=co.co_varnames,
names=co.co_names, constants=co.co_consts,
cells=self._cell_names,
linestarts=self._linestarts,
line_offset=self._line_offset,
file=output,
lasti=offset)
return output.getvalue()
def _test():
"""Simple test program to disassemble a file."""
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('infile', type=argparse.FileType(), nargs='?', default='-')
args = parser.parse_args()
with args.infile as infile:
source = infile.read()
code = compile(source, args.infile.name, "exec")
dis(code)
if __name__ == "__main__":
_test()