"""Debugger basics"""
import fnmatch
import sys
import os
from inspect import CO_GENERATOR, CO_COROUTINE, CO_ASYNC_GENERATOR
__all__ = ["BdbQuit", "Bdb", "Breakpoint"]
GENERATOR_AND_COROUTINE_FLAGS = CO_GENERATOR | CO_COROUTINE | CO_ASYNC_GENERATOR
class BdbQuit(Exception):
"""Exception to give up completely."""
class Bdb:
"""Generic Python debugger base class.
This class takes care of details of the trace facility;
a derived class should implement user interaction.
The standard debugger class (pdb.Pdb) is an example.
"""
def __init__(self, skip=None):
self.skip = set(skip) if skip else None
self.breaks = {}
self.fncache = {}
self.frame_returning = None
def canonic(self, filename):
if filename == "<" + filename[1:-1] + ">":
return filename
canonic = self.fncache.get(filename)
if not canonic:
canonic = os.path.abspath(filename)
canonic = os.path.normcase(canonic)
self.fncache[filename] = canonic
return canonic
def reset(self):
import linecache
linecache.checkcache()
self.botframe = None
self._set_stopinfo(None, None)
def trace_dispatch(self, frame, event, arg):
if self.quitting:
return # None
if event == 'line':
return self.dispatch_line(frame)
if event == 'call':
return self.dispatch_call(frame, arg)
if event == 'return':
return self.dispatch_return(frame, arg)
if event == 'exception':
return self.dispatch_exception(frame, arg)
if event == 'c_call':
return self.trace_dispatch
if event == 'c_exception':
return self.trace_dispatch
if event == 'c_return':
return self.trace_dispatch
print('bdb.Bdb.dispatch: unknown debugging event:', repr(event))
return self.trace_dispatch
def dispatch_line(self, frame):
if self.stop_here(frame) or self.break_here(frame):
self.user_line(frame)
if self.quitting: raise BdbQuit
return self.trace_dispatch
def dispatch_call(self, frame, arg):
# XXX 'arg' is no longer used
if self.botframe is None:
# First call of dispatch since reset()
self.botframe = frame.f_back # (CT) Note that this may also be None!
return self.trace_dispatch
if not (self.stop_here(frame) or self.break_anywhere(frame)):
# No need to trace this function
return # None
# Ignore call events in generator except when stepping.
if self.stopframe and frame.f_code.co_flags & GENERATOR_AND_COROUTINE_FLAGS:
return self.trace_dispatch
self.user_call(frame, arg)
if self.quitting: raise BdbQuit
return self.trace_dispatch
def dispatch_return(self, frame, arg):
if self.stop_here(frame) or frame == self.returnframe:
# Ignore return events in generator except when stepping.
if self.stopframe and frame.f_code.co_flags & GENERATOR_AND_COROUTINE_FLAGS:
return self.trace_dispatch
try:
self.frame_returning = frame
self.user_return(frame, arg)
finally:
self.frame_returning = None
if self.quitting: raise BdbQuit
# The user issued a 'next' or 'until' command.
if self.stopframe is frame and self.stoplineno != -1:
self._set_stopinfo(None, None)
return self.trace_dispatch
def dispatch_exception(self, frame, arg):
if self.stop_here(frame):
# When stepping with next/until/return in a generator frame, skip
# the internal StopIteration exception (with no traceback)
# triggered by a subiterator run with the 'yield from' statement.
if not (frame.f_code.co_flags & GENERATOR_AND_COROUTINE_FLAGS
and arg[0] is StopIteration and arg[2] is None):
self.user_exception(frame, arg)
if self.quitting: raise BdbQuit
# Stop at the StopIteration or GeneratorExit exception when the user
# has set stopframe in a generator by issuing a return command, or a
# next/until command at the last statement in the generator before the
# exception.
elif (self.stopframe and frame is not self.stopframe
and self.stopframe.f_code.co_flags & GENERATOR_AND_COROUTINE_FLAGS
and arg[0] in (StopIteration, GeneratorExit)):
self.user_exception(frame, arg)
if self.quitting: raise BdbQuit
return self.trace_dispatch
# Normally derived classes don't override the following
# methods, but they may if they want to redefine the
# definition of stopping and breakpoints.
def is_skipped_module(self, module_name):
for pattern in self.skip:
if fnmatch.fnmatch(module_name, pattern):
return True
return False
def stop_here(self, frame):
# (CT) stopframe may now also be None, see dispatch_call.
# (CT) the former test for None is therefore removed from here.
if self.skip and \
self.is_skipped_module(frame.f_globals.get('__name__')):
return False
if frame is self.stopframe:
if self.stoplineno == -1:
return False
return frame.f_lineno >= self.stoplineno
if not self.stopframe:
return True
return False
def break_here(self, frame):
filename = self.canonic(frame.f_code.co_filename)
if filename not in self.breaks:
return False
lineno = frame.f_lineno
if lineno not in self.breaks[filename]:
# The line itself has no breakpoint, but maybe the line is the
# first line of a function with breakpoint set by function name.
lineno = frame.f_code.co_firstlineno
if lineno not in self.breaks[filename]:
return False
# flag says ok to delete temp. bp
(bp, flag) = effective(filename, lineno, frame)
if bp:
self.currentbp = bp.number
if (flag and bp.temporary):
self.do_clear(str(bp.number))
return True
else:
return False
def do_clear(self, arg):
raise NotImplementedError("subclass of bdb must implement do_clear()")
def break_anywhere(self, frame):
return self.canonic(frame.f_code.co_filename) in self.breaks
# Derived classes should override the user_* methods
# to gain control.
def user_call(self, frame, argument_list):
"""This method is called when there is the remote possibility
that we ever need to stop in this function."""
pass
def user_line(self, frame):
"""This method is called when we stop or break at this line."""
pass
def user_return(self, frame, return_value):
"""This method is called when a return trap is set here."""
pass
def user_exception(self, frame, exc_info):
"""This method is called if an exception occurs,
but only if we are to stop at or just below this level."""
pass
def _set_stopinfo(self, stopframe, returnframe, stoplineno=0):
self.stopframe = stopframe
self.returnframe = returnframe
self.quitting = False
# stoplineno >= 0 means: stop at line >= the stoplineno
# stoplineno -1 means: don't stop at all
self.stoplineno = stoplineno
# Derived classes and clients can call the following methods
# to affect the stepping state.
def set_until(self, frame, lineno=None):
"""Stop when the line with the line no greater than the current one is
reached or when returning from current frame"""
# the name "until" is borrowed from gdb
if lineno is None:
lineno = frame.f_lineno + 1
self._set_stopinfo(frame, frame, lineno)
def set_step(self):
"""Stop after one line of code."""
# Issue #13183: pdb skips frames after hitting a breakpoint and running
# step commands.
# Restore the trace function in the caller (that may not have been set
# for performance reasons) when returning from the current frame.
if self.frame_returning:
caller_frame = self.frame_returning.f_back
if caller_frame and not caller_frame.f_trace:
caller_frame.f_trace = self.trace_dispatch
self._set_stopinfo(None, None)
def set_next(self, frame):
"""Stop on the next line in or below the given frame."""
self._set_stopinfo(frame, None)
def set_return(self, frame):
"""Stop when returning from the given frame."""
if frame.f_code.co_flags & GENERATOR_AND_COROUTINE_FLAGS:
self._set_stopinfo(frame, None, -1)
else:
self._set_stopinfo(frame.f_back, frame)
def set_trace(self, frame=None):
"""Start debugging from `frame`.
If frame is not specified, debugging starts from caller's frame.
"""
if frame is None:
frame = sys._getframe().f_back
self.reset()
while frame:
frame.f_trace = self.trace_dispatch
self.botframe = frame
frame = frame.f_back
self.set_step()
sys.settrace(self.trace_dispatch)
def set_continue(self):
# Don't stop except at breakpoints or when finished
self._set_stopinfo(self.botframe, None, -1)
if not self.breaks:
# no breakpoints; run without debugger overhead
sys.settrace(None)
frame = sys._getframe().f_back
while frame and frame is not self.botframe:
del frame.f_trace
frame = frame.f_back
def set_quit(self):
self.stopframe = self.botframe
self.returnframe = None
self.quitting = True
sys.settrace(None)
# Derived classes and clients can call the following methods
# to manipulate breakpoints. These methods return an
# error message is something went wrong, None if all is well.
# Set_break prints out the breakpoint line and file:lineno.
# Call self.get_*break*() to see the breakpoints or better
# for bp in Breakpoint.bpbynumber: if bp: bp.bpprint().
def set_break(self, filename, lineno, temporary=False, cond=None,
funcname=None):
filename = self.canonic(filename)
import linecache # Import as late as possible
line = linecache.getline(filename, lineno)
if not line:
return 'Line %s:%d does not exist' % (filename, lineno)
list = self.breaks.setdefault(filename, [])
if lineno not in list:
list.append(lineno)
bp = Breakpoint(filename, lineno, temporary, cond, funcname)
def _prune_breaks(self, filename, lineno):
if (filename, lineno) not in Breakpoint.bplist:
self.breaks[filename].remove(lineno)
if not self.breaks[filename]:
del self.breaks[filename]
def clear_break(self, filename, lineno):
filename = self.canonic(filename)
if filename not in self.breaks:
return 'There are no breakpoints in %s' % filename
if lineno not in self.breaks[filename]:
return 'There is no breakpoint at %s:%d' % (filename, lineno)
# If there's only one bp in the list for that file,line
# pair, then remove the breaks entry
for bp in Breakpoint.bplist[filename, lineno][:]:
bp.deleteMe()
self._prune_breaks(filename, lineno)
def clear_bpbynumber(self, arg):
try:
bp = self.get_bpbynumber(arg)
except ValueError as err:
return str(err)
bp.deleteMe()
self._prune_breaks(bp.file, bp.line)
def clear_all_file_breaks(self, filename):
filename = self.canonic(filename)
if filename not in self.breaks:
return 'There are no breakpoints in %s' % filename
for line in self.breaks[filename]:
blist = Breakpoint.bplist[filename, line]
for bp in blist:
bp.deleteMe()
del self.breaks[filename]
def clear_all_breaks(self):
if not self.breaks:
return 'There are no breakpoints'
for bp in Breakpoint.bpbynumber:
if bp:
bp.deleteMe()
self.breaks = {}
def get_bpbynumber(self, arg):
if not arg:
raise ValueError('Breakpoint number expected')
try:
number = int(arg)
except ValueError:
raise ValueError('Non-numeric breakpoint number %s' % arg)
try:
bp = Breakpoint.bpbynumber[number]
except IndexError:
raise ValueError('Breakpoint number %d out of range' % number)
if bp is None:
raise ValueError('Breakpoint %d already deleted' % number)
return bp
def get_break(self, filename, lineno):
filename = self.canonic(filename)
return filename in self.breaks and \
lineno in self.breaks[filename]
def get_breaks(self, filename, lineno):
filename = self.canonic(filename)
return filename in self.breaks and \
lineno in self.breaks[filename] and \
Breakpoint.bplist[filename, lineno] or []
def get_file_breaks(self, filename):
filename = self.canonic(filename)
if filename in self.breaks:
return self.breaks[filename]
else:
return []
def get_all_breaks(self):
return self.breaks
# Derived classes and clients can call the following method
# to get a data structure representing a stack trace.
def get_stack(self, f, t):
stack = []
if t and t.tb_frame is f:
t = t.tb_next
while f is not None:
stack.append((f, f.f_lineno))
if f is self.botframe:
break
f = f.f_back
stack.reverse()
i = max(0, len(stack) - 1)
while t is not None:
stack.append((t.tb_frame, t.tb_lineno))
t = t.tb_next
if f is None:
i = max(0, len(stack) - 1)
return stack, i
def format_stack_entry(self, frame_lineno, lprefix=': '):
import linecache, reprlib
frame, lineno = frame_lineno
filename = self.canonic(frame.f_code.co_filename)
s = '%s(%r)' % (filename, lineno)
if frame.f_code.co_name:
s += frame.f_code.co_name
else:
s += "<lambda>"
if '__args__' in frame.f_locals:
args = frame.f_locals['__args__']
else:
args = None
if args:
s += reprlib.repr(args)
else:
s += '()'
if '__return__' in frame.f_locals:
rv = frame.f_locals['__return__']
s += '->'
s += reprlib.repr(rv)
line = linecache.getline(filename, lineno, frame.f_globals)
if line:
s += lprefix + line.strip()
return s
# The following methods can be called by clients to use
# a debugger to debug a statement or an expression.
# Both can be given as a string, or a code object.
def run(self, cmd, globals=None, locals=None):
if globals is None:
import __main__
globals = __main__.__dict__
if locals is None:
locals = globals
self.reset()
if isinstance(cmd, str):
cmd = compile(cmd, "<string>", "exec")
sys.settrace(self.trace_dispatch)
try:
exec(cmd, globals, locals)
except BdbQuit:
pass
finally:
self.quitting = True
sys.settrace(None)
def runeval(self, expr, globals=None, locals=None):
if globals is None:
import __main__
globals = __main__.__dict__
if locals is None:
locals = globals
self.reset()
sys.settrace(self.trace_dispatch)
try:
return eval(expr, globals, locals)
except BdbQuit:
pass
finally:
self.quitting = True
sys.settrace(None)
def runctx(self, cmd, globals, locals):
# B/W compatibility
self.run(cmd, globals, locals)
# This method is more useful to debug a single function call.
def runcall(self, func, *args, **kwds):
self.reset()
sys.settrace(self.trace_dispatch)
res = None
try:
res = func(*args, **kwds)
except BdbQuit:
pass
finally:
self.quitting = True
sys.settrace(None)
return res
def set_trace():
Bdb().set_trace()
class Breakpoint:
"""Breakpoint class.
Implements temporary breakpoints, ignore counts, disabling and
(re)-enabling, and conditionals.
Breakpoints are indexed by number through bpbynumber and by
the file,line tuple using bplist. The former points to a
single instance of class Breakpoint. The latter points to a
list of such instances since there may be more than one
breakpoint per line.
"""
# XXX Keeping state in the class is a mistake -- this means
# you cannot have more than one active Bdb instance.
next = 1 # Next bp to be assigned
bplist = {} # indexed by (file, lineno) tuple
bpbynumber = [None] # Each entry is None or an instance of Bpt
# index 0 is unused, except for marking an
# effective break .... see effective()
def __init__(self, file, line, temporary=False, cond=None, funcname=None):
self.funcname = funcname
# Needed if funcname is not None.
self.func_first_executable_line = None
self.file = file # This better be in canonical form!
self.line = line
self.temporary = temporary
self.cond = cond
self.enabled = True
self.ignore = 0
self.hits = 0
self.number = Breakpoint.next
Breakpoint.next += 1
# Build the two lists
self.bpbynumber.append(self)
if (file, line) in self.bplist:
self.bplist[file, line].append(self)
else:
self.bplist[file, line] = [self]
def deleteMe(self):
index = (self.file, self.line)
self.bpbynumber[self.number] = None # No longer in list
self.bplist[index].remove(self)
if not self.bplist[index]:
# No more bp for this f:l combo
del self.bplist[index]
def enable(self):
self.enabled = True
def disable(self):
self.enabled = False
def bpprint(self, out=None):
if out is None:
out = sys.stdout
print(self.bpformat(), file=out)
def bpformat(self):
if self.temporary:
disp = 'del '
else:
disp = 'keep '
if self.enabled:
disp = disp + 'yes '
else:
disp = disp + 'no '
ret = '%-4dbreakpoint %s at %s:%d' % (self.number, disp,
self.file, self.line)
if self.cond:
ret += '\n\tstop only if %s' % (self.cond,)
if self.ignore:
ret += '\n\tignore next %d hits' % (self.ignore,)
if self.hits:
if self.hits > 1:
ss = 's'
else:
ss = ''
ret += '\n\tbreakpoint already hit %d time%s' % (self.hits, ss)
return ret
def __str__(self):
return 'breakpoint %s at %s:%s' % (self.number, self.file, self.line)
# -----------end of Breakpoint class----------
def checkfuncname(b, frame):
"""Check whether we should break here because of `b.funcname`."""
if not b.funcname:
# Breakpoint was set via line number.
if b.line != frame.f_lineno:
# Breakpoint was set at a line with a def statement and the function
# defined is called: don't break.
return False
return True
# Breakpoint set via function name.
if frame.f_code.co_name != b.funcname:
# It's not a function call, but rather execution of def statement.
return False
# We are in the right frame.
if not b.func_first_executable_line:
# The function is entered for the 1st time.
b.func_first_executable_line = frame.f_lineno
if b.func_first_executable_line != frame.f_lineno:
# But we are not at the first line number: don't break.
return False
return True
# Determines if there is an effective (active) breakpoint at this
# line of code. Returns breakpoint number or 0 if none
def effective(file, line, frame):
"""Determine which breakpoint for this file:line is to be acted upon.
Called only if we know there is a bpt at this
location. Returns breakpoint that was triggered and a flag
that indicates if it is ok to delete a temporary bp.
"""
possibles = Breakpoint.bplist[file, line]
for b in possibles:
if not b.enabled:
continue
if not checkfuncname(b, frame):
continue
# Count every hit when bp is enabled
b.hits += 1
if not b.cond:
# If unconditional, and ignoring go on to next, else break
if b.ignore > 0:
b.ignore -= 1
continue
else:
# breakpoint and marker that it's ok to delete if temporary
return (b, True)
else:
# Conditional bp.
# Ignore count applies only to those bpt hits where the
# condition evaluates to true.
try:
val = eval(b.cond, frame.f_globals, frame.f_locals)
if val:
if b.ignore > 0:
b.ignore -= 1
# continue
else:
return (b, True)
# else:
# continue
except:
# if eval fails, most conservative thing is to stop on
# breakpoint regardless of ignore count. Don't delete
# temporary, as another hint to user.
return (b, False)
return (None, None)
# -------------------- testing --------------------
class Tdb(Bdb):
def user_call(self, frame, args):
name = frame.f_code.co_name
if not name: name = '???'
print('+++ call', name, args)
def user_line(self, frame):
import linecache
name = frame.f_code.co_name
if not name: name = '???'
fn = self.canonic(frame.f_code.co_filename)
line = linecache.getline(fn, frame.f_lineno, frame.f_globals)
print('+++', fn, frame.f_lineno, name, ':', line.strip())
def user_return(self, frame, retval):
print('+++ return', retval)
def user_exception(self, frame, exc_stuff):
print('+++ exception', exc_stuff)
self.set_continue()
def foo(n):
print('foo(', n, ')')
x = bar(n*10)
print('bar returned', x)
def bar(a):
print('bar(', a, ')')
return a/2
def test():
t = Tdb()
t.run('import bdb; bdb.foo(10)')
