/usr/lib/python3/dist-packages/construct/debug.py is in python3-construct 2.8.16-0.2.
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Debugging utilities for constructs
"""
import sys
import traceback
import pdb
import inspect
from construct import *
from construct.lib import *
class Probe(Construct):
r"""
A probe: dumps the context, stack frames, and stream content to the screen to aid the debugging process.
:param name: the display name
:param show_stream: whether or not to show stream contents. default is True. the stream must be seekable.
:param show_context: whether or not to show the context. default is True.
:param show_stack: whether or not to show the upper stack frames. default is True.
:param stream_lookahead: the number of bytes to dump when show_stack is set. default is 100.
Example::
>>> Struct("count"/Byte, "items"/Byte[this.count], Probe()).parse(b"\x05abcde")
================================================================================
Probe <unnamed 3>
EOF reached
Container:
count = 5
items = ListContainer:
97
98
99
100
101
================================================================================
Container(count=5)(items=[97, 98, 99, 100, 101])
>>> (Byte >> Probe()).parse(b"?")
================================================================================
Probe <unnamed 1>
EOF reached
Container:
0 = 63
================================================================================
[63, None]
"""
__slots__ = ["printname", "show_stream", "show_context", "show_stack", "stream_lookahead", "func"]
counter = 0
def __init__(self, name=None, show_stream=True, show_context=True, show_stack=True, stream_lookahead=128, func=None):
super(Probe, self).__init__()
if name is None:
Probe.counter += 1
name = "<unnamed %d>" % Probe.counter
self.printname = name
self.show_stream = show_stream
self.show_context = show_context
self.show_stack = show_stack
self.stream_lookahead = stream_lookahead
self.func = func
self.flagbuildnone = True
def __repr__(self):
return "<%s: %s>" % (self.__class__.__name__, self.printname)
def _parse(self, stream, context, path):
self.printout(stream, context, path)
def _build(self, obj, stream, context, path):
self.printout(stream, context, path)
def _sizeof(self, context, path):
self.printout(None, context, path)
return 0
def printout(self, stream, context, path):
print("================================================================================")
print("Probe %s" % self.printname)
print("path is %s, func is %s" % (path, self.func))
if self.show_stream and stream is not None:
fallback = stream.tell()
datafollows = stream.read(self.stream_lookahead)
stream.seek(fallback)
if not datafollows:
print("EOF reached")
else:
print(hexdump(datafollows, 32))
if self.show_context:
if self.func:
try:
context = self.func(context)
print(context)
except Exception as e:
print("Failed to compute `%r` on the context" % self.func)
else:
print(context)
# if self.show_stack:
# stack = ListContainer()
# print("Stack: ")
# frames = [s[0] for s in inspect.stack()][1:-1]
# for f in reversed(frames):
# a = Container()
# a.__update__(f.f_locals)
# stack.append(a)
# # print(f.f_locals)
# print(stack)
print("================================================================================")
def ProbeInto(func):
r"""
ProbeInto looks inside the context and extracts a part of it using a lambda instead of printing the entire context.
Example::
>>> st = "junk"/RepeatUntil(obj_ == 0,Byte) + "num"/Byte + Probe()
>>> st.parse(b"xcnzxmbjskahuiwerhquiehnsdjk\x00\xff")
================================================================================
Probe <unnamed 5>
path is parsing
EOF reached
Container:
junk = ListContainer:
120
99
110
122
120
109
98
106
115
107
97
104
117
105
119
101
114
104
113
117
105
101
104
110
115
100
106
107
0
num = 255
================================================================================
Container(junk=[120, 99, 110, 122, 120, 109, 98, 106, 115, 107, 97, 104, 117, 105, 119, 101, 114, 104, 113, 117, 105, 101, 104, 110, 115, 100, 106, 107, 0])(num=255)
>>> st = "junk"/RepeatUntil(obj_ == 0,Byte) + "num"/Byte + ProbeInto(this.num)
>>> st.parse(b"xcnzxmbjskahuiwerhquiehnsdjk\x00\xff")
================================================================================
Probe <unnamed 6>
path is parsing
EOF reached
255
================================================================================
Container(junk=[120, 99, 110, 122, 120, 109, 98, 106, 115, 107, 97, 104, 117, 105, 119, 101, 114, 104, 113, 117, 105, 101, 104, 110, 115, 100, 106, 107, 0])(num=255)
"""
return Probe(func=func)
class Debugger(Subconstruct):
r"""
A pdb-based debugger. When an exception occurs in the subcon, a debugger will appear and allow you to debug the error (and even fix it on-the-fly).
:param subcon: the subcon to debug
Example::
>>> Debugger(Byte[3]).build([])
================================================================================
Debugging exception of <Range: None>:
File "/home/arkadiusz/Dokumenty/GitHub/construct/construct/debug.py", line 116, in _build
obj.stack.append(a)
File "/home/arkadiusz/Dokumenty/GitHub/construct/construct/core.py", line 1069, in _build
raise RangeError("expected from %d to %d elements, found %d" % (self.min, self.max, len(obj)))
construct.core.RangeError: expected from 3 to 3 elements, found 0
> /home/arkadiusz/Dokumenty/GitHub/construct/construct/core.py(1069)_build()
-> raise RangeError("expected from %d to %d elements, found %d" % (self.min, self.max, len(obj)))
(Pdb)
================================================================================
>>> format = Struct(
... "spam" / Debugger(Enum(Byte, A=1, B=2, C=3)),
... )
>>> format.parse(b"\xff")
================================================================================
Debugging exception of <Mapping: None>:
File "/home/arkadiusz/Dokumenty/GitHub/construct/construct/core.py", line 2578, in _decode
return self.decoding[obj]
KeyError: 255
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/home/arkadiusz/Dokumenty/GitHub/construct/construct/debug.py", line 127, in _parse
return self.subcon._parse(stream, context)
File "/home/arkadiusz/Dokumenty/GitHub/construct/construct/core.py", line 308, in _parse
return self._decode(self.subcon._parse(stream, context), context)
File "/home/arkadiusz/Dokumenty/GitHub/construct/construct/core.py", line 2583, in _decode
raise MappingError("no decoding mapping for %r" % (obj,))
construct.core.MappingError: no decoding mapping for 255
(you can set the value of 'self.retval', which will be returned)
> /home/arkadiusz/Dokumenty/GitHub/construct/construct/core.py(2583)_decode()
-> raise MappingError("no decoding mapping for %r" % (obj,))
(Pdb) self.retval = "???"
(Pdb) q
"""
__slots__ = ["retval"]
def _parse(self, stream, context, path):
try:
return self.subcon._parse(stream, context, path)
except Exception:
self.retval = NotImplemented
self.handle_exc(path, msg="(you can set the value of 'self.retval', which will be returned)")
if self.retval is NotImplemented:
raise
else:
return self.retval
def _build(self, obj, stream, context, path):
try:
self.subcon._build(obj, stream, context, path)
except Exception:
self.handle_exc(path)
def _sizeof(self, context, path):
try:
self.subcon._sizeof(context, path)
except Exception:
self.handle_exc(path)
def handle_exc(self, path, msg=None):
print("================================================================================")
print("Debugging exception of %s:" % self.subcon)
print("path is %s" % path)
print("".join(traceback.format_exception(*sys.exc_info())[1:]))
if msg:
print(msg)
pdb.post_mortem(sys.exc_info()[2])
print("================================================================================")
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