mirror of https://github.com/python/cpython
568 lines
21 KiB
Python
568 lines
21 KiB
Python
"""Extract, format and print information about Python stack traces."""
|
|
|
|
import collections
|
|
import itertools
|
|
import linecache
|
|
import sys
|
|
|
|
__all__ = ['extract_stack', 'extract_tb', 'format_exception',
|
|
'format_exception_only', 'format_list', 'format_stack',
|
|
'format_tb', 'print_exc', 'format_exc', 'print_exception',
|
|
'print_last', 'print_stack', 'print_tb', 'clear_frames',
|
|
'FrameSummary', 'StackSummary', 'TracebackException',
|
|
'walk_stack', 'walk_tb']
|
|
|
|
#
|
|
# Formatting and printing lists of traceback lines.
|
|
#
|
|
|
|
def print_list(extracted_list, file=None):
|
|
"""Print the list of tuples as returned by extract_tb() or
|
|
extract_stack() as a formatted stack trace to the given file."""
|
|
if file is None:
|
|
file = sys.stderr
|
|
for item in StackSummary.from_list(extracted_list).format():
|
|
print(item, file=file, end="")
|
|
|
|
def format_list(extracted_list):
|
|
"""Format a list of traceback entry tuples for printing.
|
|
|
|
Given a list of tuples as returned by extract_tb() or
|
|
extract_stack(), return a list of strings ready for printing.
|
|
Each string in the resulting list corresponds to the item with the
|
|
same index in the argument list. Each string ends in a newline;
|
|
the strings may contain internal newlines as well, for those items
|
|
whose source text line is not None.
|
|
"""
|
|
return StackSummary.from_list(extracted_list).format()
|
|
|
|
#
|
|
# Printing and Extracting Tracebacks.
|
|
#
|
|
|
|
def print_tb(tb, limit=None, file=None):
|
|
"""Print up to 'limit' stack trace entries from the traceback 'tb'.
|
|
|
|
If 'limit' is omitted or None, all entries are printed. If 'file'
|
|
is omitted or None, the output goes to sys.stderr; otherwise
|
|
'file' should be an open file or file-like object with a write()
|
|
method.
|
|
"""
|
|
print_list(extract_tb(tb, limit=limit), file=file)
|
|
|
|
def format_tb(tb, limit=None):
|
|
"""A shorthand for 'format_list(extract_tb(tb, limit))'."""
|
|
return extract_tb(tb, limit=limit).format()
|
|
|
|
def extract_tb(tb, limit=None):
|
|
"""Return list of up to limit pre-processed entries from traceback.
|
|
|
|
This is useful for alternate formatting of stack traces. If
|
|
'limit' is omitted or None, all entries are extracted. A
|
|
pre-processed stack trace entry is a quadruple (filename, line
|
|
number, function name, text) representing the information that is
|
|
usually printed for a stack trace. The text is a string with
|
|
leading and trailing whitespace stripped; if the source is not
|
|
available it is None.
|
|
"""
|
|
return StackSummary.extract(walk_tb(tb), limit=limit)
|
|
|
|
#
|
|
# Exception formatting and output.
|
|
#
|
|
|
|
_cause_message = (
|
|
"\nThe above exception was the direct cause "
|
|
"of the following exception:\n\n")
|
|
|
|
_context_message = (
|
|
"\nDuring handling of the above exception, "
|
|
"another exception occurred:\n\n")
|
|
|
|
|
|
def print_exception(etype, value, tb, limit=None, file=None, chain=True):
|
|
"""Print exception up to 'limit' stack trace entries from 'tb' to 'file'.
|
|
|
|
This differs from print_tb() in the following ways: (1) if
|
|
traceback is not None, it prints a header "Traceback (most recent
|
|
call last):"; (2) it prints the exception type and value after the
|
|
stack trace; (3) if type is SyntaxError and value has the
|
|
appropriate format, it prints the line where the syntax error
|
|
occurred with a caret on the next line indicating the approximate
|
|
position of the error.
|
|
"""
|
|
# format_exception has ignored etype for some time, and code such as cgitb
|
|
# passes in bogus values as a result. For compatibility with such code we
|
|
# ignore it here (rather than in the new TracebackException API).
|
|
if file is None:
|
|
file = sys.stderr
|
|
for line in TracebackException(
|
|
type(value), value, tb, limit=limit).format(chain=chain):
|
|
print(line, file=file, end="")
|
|
|
|
|
|
def format_exception(etype, value, tb, limit=None, chain=True):
|
|
"""Format a stack trace and the exception information.
|
|
|
|
The arguments have the same meaning as the corresponding arguments
|
|
to print_exception(). The return value is a list of strings, each
|
|
ending in a newline and some containing internal newlines. When
|
|
these lines are concatenated and printed, exactly the same text is
|
|
printed as does print_exception().
|
|
"""
|
|
# format_exception has ignored etype for some time, and code such as cgitb
|
|
# passes in bogus values as a result. For compatibility with such code we
|
|
# ignore it here (rather than in the new TracebackException API).
|
|
return list(TracebackException(
|
|
type(value), value, tb, limit=limit).format(chain=chain))
|
|
|
|
|
|
def format_exception_only(etype, value):
|
|
"""Format the exception part of a traceback.
|
|
|
|
The arguments are the exception type and value such as given by
|
|
sys.last_type and sys.last_value. The return value is a list of
|
|
strings, each ending in a newline.
|
|
|
|
Normally, the list contains a single string; however, for
|
|
SyntaxError exceptions, it contains several lines that (when
|
|
printed) display detailed information about where the syntax
|
|
error occurred.
|
|
|
|
The message indicating which exception occurred is always the last
|
|
string in the list.
|
|
|
|
"""
|
|
return list(TracebackException(etype, value, None).format_exception_only())
|
|
|
|
|
|
# -- not offical API but folk probably use these two functions.
|
|
|
|
def _format_final_exc_line(etype, value):
|
|
valuestr = _some_str(value)
|
|
if value == 'None' or value is None or not valuestr:
|
|
line = "%s\n" % etype
|
|
else:
|
|
line = "%s: %s\n" % (etype, valuestr)
|
|
return line
|
|
|
|
def _some_str(value):
|
|
try:
|
|
return str(value)
|
|
except:
|
|
return '<unprintable %s object>' % type(value).__name__
|
|
|
|
# --
|
|
|
|
def print_exc(limit=None, file=None, chain=True):
|
|
"""Shorthand for 'print_exception(*sys.exc_info(), limit, file)'."""
|
|
print_exception(*sys.exc_info(), limit=limit, file=file, chain=chain)
|
|
|
|
def format_exc(limit=None, chain=True):
|
|
"""Like print_exc() but return a string."""
|
|
return "".join(format_exception(*sys.exc_info(), limit=limit, chain=chain))
|
|
|
|
def print_last(limit=None, file=None, chain=True):
|
|
"""This is a shorthand for 'print_exception(sys.last_type,
|
|
sys.last_value, sys.last_traceback, limit, file)'."""
|
|
if not hasattr(sys, "last_type"):
|
|
raise ValueError("no last exception")
|
|
print_exception(sys.last_type, sys.last_value, sys.last_traceback,
|
|
limit, file, chain)
|
|
|
|
#
|
|
# Printing and Extracting Stacks.
|
|
#
|
|
|
|
def print_stack(f=None, limit=None, file=None):
|
|
"""Print a stack trace from its invocation point.
|
|
|
|
The optional 'f' argument can be used to specify an alternate
|
|
stack frame at which to start. The optional 'limit' and 'file'
|
|
arguments have the same meaning as for print_exception().
|
|
"""
|
|
print_list(extract_stack(f, limit=limit), file=file)
|
|
|
|
|
|
def format_stack(f=None, limit=None):
|
|
"""Shorthand for 'format_list(extract_stack(f, limit))'."""
|
|
return format_list(extract_stack(f, limit=limit))
|
|
|
|
|
|
def extract_stack(f=None, limit=None):
|
|
"""Extract the raw traceback from the current stack frame.
|
|
|
|
The return value has the same format as for extract_tb(). The
|
|
optional 'f' and 'limit' arguments have the same meaning as for
|
|
print_stack(). Each item in the list is a quadruple (filename,
|
|
line number, function name, text), and the entries are in order
|
|
from oldest to newest stack frame.
|
|
"""
|
|
stack = StackSummary.extract(walk_stack(f), limit=limit)
|
|
stack.reverse()
|
|
return stack
|
|
|
|
|
|
def clear_frames(tb):
|
|
"Clear all references to local variables in the frames of a traceback."
|
|
while tb is not None:
|
|
try:
|
|
tb.tb_frame.clear()
|
|
except RuntimeError:
|
|
# Ignore the exception raised if the frame is still executing.
|
|
pass
|
|
tb = tb.tb_next
|
|
|
|
|
|
class FrameSummary:
|
|
"""A single frame from a traceback.
|
|
|
|
- :attr:`filename` The filename for the frame.
|
|
- :attr:`lineno` The line within filename for the frame that was
|
|
active when the frame was captured.
|
|
- :attr:`name` The name of the function or method that was executing
|
|
when the frame was captured.
|
|
- :attr:`line` The text from the linecache module for the
|
|
of code that was running when the frame was captured.
|
|
- :attr:`locals` Either None if locals were not supplied, or a dict
|
|
mapping the name to the repr() of the variable.
|
|
"""
|
|
|
|
__slots__ = ('filename', 'lineno', 'name', '_line', 'locals')
|
|
|
|
def __init__(self, filename, lineno, name, *, lookup_line=True,
|
|
locals=None, line=None):
|
|
"""Construct a FrameSummary.
|
|
|
|
:param lookup_line: If True, `linecache` is consulted for the source
|
|
code line. Otherwise, the line will be looked up when first needed.
|
|
:param locals: If supplied the frame locals, which will be captured as
|
|
object representations.
|
|
:param line: If provided, use this instead of looking up the line in
|
|
the linecache.
|
|
"""
|
|
self.filename = filename
|
|
self.lineno = lineno
|
|
self.name = name
|
|
self._line = line
|
|
if lookup_line:
|
|
self.line
|
|
self.locals = \
|
|
dict((k, repr(v)) for k, v in locals.items()) if locals else None
|
|
|
|
def __eq__(self, other):
|
|
return (self.filename == other.filename and
|
|
self.lineno == other.lineno and
|
|
self.name == other.name and
|
|
self.locals == other.locals)
|
|
|
|
def __getitem__(self, pos):
|
|
return (self.filename, self.lineno, self.name, self.line)[pos]
|
|
|
|
def __iter__(self):
|
|
return iter([self.filename, self.lineno, self.name, self.line])
|
|
|
|
def __repr__(self):
|
|
return "<FrameSummary file {filename}, line {lineno} in {name}>".format(
|
|
filename=self.filename, lineno=self.lineno, name=self.name)
|
|
|
|
@property
|
|
def line(self):
|
|
if self._line is None:
|
|
self._line = linecache.getline(self.filename, self.lineno).strip()
|
|
return self._line
|
|
|
|
|
|
def walk_stack(f):
|
|
"""Walk a stack yielding the frame and line number for each frame.
|
|
|
|
This will follow f.f_back from the given frame. If no frame is given, the
|
|
current stack is used. Usually used with StackSummary.extract.
|
|
"""
|
|
if f is None:
|
|
f = sys._getframe().f_back.f_back
|
|
while f is not None:
|
|
yield f, f.f_lineno
|
|
f = f.f_back
|
|
|
|
|
|
def walk_tb(tb):
|
|
"""Walk a traceback yielding the frame and line number for each frame.
|
|
|
|
This will follow tb.tb_next (and thus is in the opposite order to
|
|
walk_stack). Usually used with StackSummary.extract.
|
|
"""
|
|
while tb is not None:
|
|
yield tb.tb_frame, tb.tb_lineno
|
|
tb = tb.tb_next
|
|
|
|
|
|
class StackSummary(list):
|
|
"""A stack of frames."""
|
|
|
|
@classmethod
|
|
def extract(klass, frame_gen, *, limit=None, lookup_lines=True,
|
|
capture_locals=False):
|
|
"""Create a StackSummary from a traceback or stack object.
|
|
|
|
:param frame_gen: A generator that yields (frame, lineno) tuples to
|
|
include in the stack.
|
|
:param limit: None to include all frames or the number of frames to
|
|
include.
|
|
:param lookup_lines: If True, lookup lines for each frame immediately,
|
|
otherwise lookup is deferred until the frame is rendered.
|
|
:param capture_locals: If True, the local variables from each frame will
|
|
be captured as object representations into the FrameSummary.
|
|
"""
|
|
if limit is None:
|
|
limit = getattr(sys, 'tracebacklimit', None)
|
|
if limit is not None and limit < 0:
|
|
limit = 0
|
|
if limit is not None:
|
|
if limit >= 0:
|
|
frame_gen = itertools.islice(frame_gen, limit)
|
|
else:
|
|
frame_gen = collections.deque(frame_gen, maxlen=-limit)
|
|
|
|
result = klass()
|
|
fnames = set()
|
|
for f, lineno in frame_gen:
|
|
co = f.f_code
|
|
filename = co.co_filename
|
|
name = co.co_name
|
|
|
|
fnames.add(filename)
|
|
linecache.lazycache(filename, f.f_globals)
|
|
# Must defer line lookups until we have called checkcache.
|
|
if capture_locals:
|
|
f_locals = f.f_locals
|
|
else:
|
|
f_locals = None
|
|
result.append(FrameSummary(
|
|
filename, lineno, name, lookup_line=False, locals=f_locals))
|
|
for filename in fnames:
|
|
linecache.checkcache(filename)
|
|
# If immediate lookup was desired, trigger lookups now.
|
|
if lookup_lines:
|
|
for f in result:
|
|
f.line
|
|
return result
|
|
|
|
@classmethod
|
|
def from_list(klass, a_list):
|
|
"""Create a StackSummary from a simple list of tuples.
|
|
|
|
This method supports the older Python API. Each tuple should be a
|
|
4-tuple with (filename, lineno, name, line) elements.
|
|
"""
|
|
# While doing a fast-path check for isinstance(a_list, StackSummary) is
|
|
# appealing, idlelib.run.cleanup_traceback and other similar code may
|
|
# break this by making arbitrary frames plain tuples, so we need to
|
|
# check on a frame by frame basis.
|
|
result = StackSummary()
|
|
for frame in a_list:
|
|
if isinstance(frame, FrameSummary):
|
|
result.append(frame)
|
|
else:
|
|
filename, lineno, name, line = frame
|
|
result.append(FrameSummary(filename, lineno, name, line=line))
|
|
return result
|
|
|
|
def format(self):
|
|
"""Format the stack ready for printing.
|
|
|
|
Returns a list of strings ready for printing. Each string in the
|
|
resulting list corresponds to a single frame from the stack.
|
|
Each string ends in a newline; the strings may contain internal
|
|
newlines as well, for those items with source text lines.
|
|
"""
|
|
result = []
|
|
for frame in self:
|
|
row = []
|
|
row.append(' File "{}", line {}, in {}\n'.format(
|
|
frame.filename, frame.lineno, frame.name))
|
|
if frame.line:
|
|
row.append(' {}\n'.format(frame.line.strip()))
|
|
if frame.locals:
|
|
for name, value in sorted(frame.locals.items()):
|
|
row.append(' {name} = {value}\n'.format(name=name, value=value))
|
|
result.append(''.join(row))
|
|
return result
|
|
|
|
|
|
class TracebackException:
|
|
"""An exception ready for rendering.
|
|
|
|
The traceback module captures enough attributes from the original exception
|
|
to this intermediary form to ensure that no references are held, while
|
|
still being able to fully print or format it.
|
|
|
|
Use `from_exception` to create TracebackException instances from exception
|
|
objects, or the constructor to create TracebackException instances from
|
|
individual components.
|
|
|
|
- :attr:`__cause__` A TracebackException of the original *__cause__*.
|
|
- :attr:`__context__` A TracebackException of the original *__context__*.
|
|
- :attr:`__suppress_context__` The *__suppress_context__* value from the
|
|
original exception.
|
|
- :attr:`stack` A `StackSummary` representing the traceback.
|
|
- :attr:`exc_type` The class of the original traceback.
|
|
- :attr:`filename` For syntax errors - the filename where the error
|
|
occured.
|
|
- :attr:`lineno` For syntax errors - the linenumber where the error
|
|
occured.
|
|
- :attr:`text` For syntax errors - the text where the error
|
|
occured.
|
|
- :attr:`offset` For syntax errors - the offset into the text where the
|
|
error occured.
|
|
- :attr:`msg` For syntax errors - the compiler error message.
|
|
"""
|
|
|
|
def __init__(self, exc_type, exc_value, exc_traceback, *, limit=None,
|
|
lookup_lines=True, capture_locals=False, _seen=None):
|
|
# NB: we need to accept exc_traceback, exc_value, exc_traceback to
|
|
# permit backwards compat with the existing API, otherwise we
|
|
# need stub thunk objects just to glue it together.
|
|
# Handle loops in __cause__ or __context__.
|
|
if _seen is None:
|
|
_seen = set()
|
|
_seen.add(exc_value)
|
|
# Gracefully handle (the way Python 2.4 and earlier did) the case of
|
|
# being called with no type or value (None, None, None).
|
|
if (exc_value and exc_value.__cause__ is not None
|
|
and exc_value.__cause__ not in _seen):
|
|
cause = TracebackException(
|
|
type(exc_value.__cause__),
|
|
exc_value.__cause__,
|
|
exc_value.__cause__.__traceback__,
|
|
limit=limit,
|
|
lookup_lines=False,
|
|
capture_locals=capture_locals,
|
|
_seen=_seen)
|
|
else:
|
|
cause = None
|
|
if (exc_value and exc_value.__context__ is not None
|
|
and exc_value.__context__ not in _seen):
|
|
context = TracebackException(
|
|
type(exc_value.__context__),
|
|
exc_value.__context__,
|
|
exc_value.__context__.__traceback__,
|
|
limit=limit,
|
|
lookup_lines=False,
|
|
capture_locals=capture_locals,
|
|
_seen=_seen)
|
|
else:
|
|
context = None
|
|
self.exc_traceback = exc_traceback
|
|
self.__cause__ = cause
|
|
self.__context__ = context
|
|
self.__suppress_context__ = \
|
|
exc_value.__suppress_context__ if exc_value else False
|
|
# TODO: locals.
|
|
self.stack = StackSummary.extract(
|
|
walk_tb(exc_traceback), limit=limit, lookup_lines=lookup_lines,
|
|
capture_locals=capture_locals)
|
|
self.exc_type = exc_type
|
|
# Capture now to permit freeing resources: only complication is in the
|
|
# unofficial API _format_final_exc_line
|
|
self._str = _some_str(exc_value)
|
|
if exc_type and issubclass(exc_type, SyntaxError):
|
|
# Handle SyntaxError's specially
|
|
self.filename = exc_value.filename
|
|
self.lineno = str(exc_value.lineno)
|
|
self.text = exc_value.text
|
|
self.offset = exc_value.offset
|
|
self.msg = exc_value.msg
|
|
if lookup_lines:
|
|
self._load_lines()
|
|
|
|
@classmethod
|
|
def from_exception(cls, exc, *args, **kwargs):
|
|
"""Create a TracebackException from an exception."""
|
|
return cls(type(exc), exc, exc.__traceback__, *args, **kwargs)
|
|
|
|
def _load_lines(self):
|
|
"""Private API. force all lines in the stack to be loaded."""
|
|
for frame in self.stack:
|
|
frame.line
|
|
if self.__context__:
|
|
self.__context__._load_lines()
|
|
if self.__cause__:
|
|
self.__cause__._load_lines()
|
|
|
|
def __eq__(self, other):
|
|
return self.__dict__ == other.__dict__
|
|
|
|
def __str__(self):
|
|
return self._str
|
|
|
|
def format_exception_only(self):
|
|
"""Format the exception part of the traceback.
|
|
|
|
The return value is a generator of strings, each ending in a newline.
|
|
|
|
Normally, the generator emits a single string; however, for
|
|
SyntaxError exceptions, it emites several lines that (when
|
|
printed) display detailed information about where the syntax
|
|
error occurred.
|
|
|
|
The message indicating which exception occurred is always the last
|
|
string in the output.
|
|
"""
|
|
if self.exc_type is None:
|
|
yield _format_final_exc_line(None, self._str)
|
|
return
|
|
|
|
stype = self.exc_type.__qualname__
|
|
smod = self.exc_type.__module__
|
|
if smod not in ("__main__", "builtins"):
|
|
stype = smod + '.' + stype
|
|
|
|
if not issubclass(self.exc_type, SyntaxError):
|
|
yield _format_final_exc_line(stype, self._str)
|
|
return
|
|
|
|
# It was a syntax error; show exactly where the problem was found.
|
|
filename = self.filename or "<string>"
|
|
lineno = str(self.lineno) or '?'
|
|
yield ' File "{}", line {}\n'.format(filename, lineno)
|
|
|
|
badline = self.text
|
|
offset = self.offset
|
|
if badline is not None:
|
|
yield ' {}\n'.format(badline.strip())
|
|
if offset is not None:
|
|
caretspace = badline.rstrip('\n')
|
|
offset = min(len(caretspace), offset) - 1
|
|
caretspace = caretspace[:offset].lstrip()
|
|
# non-space whitespace (likes tabs) must be kept for alignment
|
|
caretspace = ((c.isspace() and c or ' ') for c in caretspace)
|
|
yield ' {}^\n'.format(''.join(caretspace))
|
|
msg = self.msg or "<no detail available>"
|
|
yield "{}: {}\n".format(stype, msg)
|
|
|
|
def format(self, *, chain=True):
|
|
"""Format the exception.
|
|
|
|
If chain is not *True*, *__cause__* and *__context__* will not be formatted.
|
|
|
|
The return value is a generator of strings, each ending in a newline and
|
|
some containing internal newlines. `print_exception` is a wrapper around
|
|
this method which just prints the lines to a file.
|
|
|
|
The message indicating which exception occurred is always the last
|
|
string in the output.
|
|
"""
|
|
if chain:
|
|
if self.__cause__ is not None:
|
|
yield from self.__cause__.format(chain=chain)
|
|
yield _cause_message
|
|
elif (self.__context__ is not None and
|
|
not self.__suppress_context__):
|
|
yield from self.__context__.format(chain=chain)
|
|
yield _context_message
|
|
if self.exc_traceback is not None:
|
|
yield 'Traceback (most recent call last):\n'
|
|
yield from self.stack.format()
|
|
yield from self.format_exception_only()
|