DebugClients/Python3/DebugBase.py

# -*- coding: utf-8 -*-

# Copyright (c) 2009 - 2016 Detlev Offenbach <detlev@die-offenbachs.de>
#

"""
Module implementing the debug base class.
"""

import sys
import bdb
import os
import atexit
import inspect
import ctypes
import _thread
import time
from inspect import CO_GENERATOR

from DebugProtocol import ResponseClearWatch, ResponseClearBreak, \
    ResponseLine, ResponseSyntax, ResponseException, CallTrace
from DebugUtilities import getargvalues, formatargvalues
from BreakpointWatch import Breakpoint, Watch

gRecursionLimit = 64


def printerr(s):
    """
    Module function used for debugging the debug client.
    
    @param s data to be printed
    """
    sys.__stderr__.write('{0!s}\n'.format(s))
    sys.__stderr__.flush()


def setRecursionLimit(limit):
    """
    Module function to set the recursion limit.
    
    @param limit recursion limit (integer)
    """
    global gRecursionLimit
    gRecursionLimit = limit


class DebugBase(bdb.Bdb):
    """
    Class implementing base class of the debugger.

    Provides simple wrapper methods around bdb for the 'owning' client to
    call to step etc.
    """
    # Don't thrust distutils.sysconfig.get_python_lib: possible case mismatch
    #  on Windows
    lib = os.path.dirname(bdb.__file__)
    # tuple required because it's accessed a lot of times by startswith method
    pathsToSkip = ('<', os.path.dirname(__file__), bdb.__file__[:-1])
    filesToSkip = {}

    # cache for fixed file names
    _fnCache = {}

    def __init__(self, dbgClient):
        """
        Constructor
        
        @param dbgClient the owning client
        """
        bdb.Bdb.__init__(self)

        self._dbgClient = dbgClient
        self._mainThread = True
        
        self.tracePythonLibs(0)
        
        self.__isBroken = False
        self.cFrame = None
        
        # current frame we are at
        self.currentFrame = None
        
        # frame that we are stepping in, can be different than currentFrame
        self.stepFrame = None
        
        # provide a hook to perform a hard breakpoint
        # Use it like this:
        # if hasattr(sys, 'breakpoint): sys.breakpoint()
        sys.breakpoint = self.set_trace
        
        # initialize parent
        bdb.Bdb.reset(self)
        
        self.__recursionDepth = -1
        self.setRecursionDepth(inspect.currentframe())
        
        # background task to periodicaly check for client interactions
        self.eventPollFlag = False
        self.timer = _thread.start_new_thread(self.__eventPollTimer, ())

    def __eventPollTimer(self):
        """
        Private method to set a flag every 0.5 s to check for new messages.
        """
        while True:
            time.sleep(0.5)
            self.eventPollFlag = True
    
    def getCurrentFrame(self):
        """
        Public method to return the current frame.
        
        @return the current frame
        """
        return self.currentFrame
    
    def getFrameLocals(self, frmnr=0):
        """
        Public method to return the locals dictionary of the current frame
        or a frame below.
        
        @keyparam frmnr distance of frame to get locals dictionary of. 0 is
            the current frame (int)
        @return locals dictionary of the frame
        """
        f = self.currentFrame
        while f is not None and frmnr > 0:
            f = f.f_back
            frmnr -= 1
        return f.f_locals
    
    def storeFrameLocals(self, frmnr=0):
        """
        Public method to store the locals into the frame, so an access to
        frame.f_locals returns the last data.
        
        @keyparam frmnr distance of frame to store locals dictionary to. 0 is
            the current frame (int)
        """
        cf = self.currentFrame
        while cf is not None and frmnr > 0:
            cf = cf.f_back
            frmnr -= 1
        ctypes.pythonapi.PyFrame_LocalsToFast(
            ctypes.py_object(cf),
            ctypes.c_int(0))
    
    def step(self, traceMode):
        """
        Public method to perform a step operation in this thread.
        
        @param traceMode If it is True, then the step is a step into,
              otherwise it is a step over.
        """
        self.stepFrame = self.currentFrame
        
        if traceMode:
            self.currentFrame = None
            self.set_step()
        else:
            self.set_next(self.currentFrame)
    
    def stepOut(self):
        """
        Public method to perform a step out of the current call.
        """
        self.stepFrame = self.currentFrame
        self.set_return(self.currentFrame)
    
    def go(self, special):
        """
        Public method to resume the thread.

        It resumes the thread stopping only at breakpoints or exceptions.
        
        @param special flag indicating a special continue operation
        """
        self.currentFrame = None
        self.set_continue(special)
    
    def setRecursionDepth(self, frame):
        """
        Public method to determine the current recursion depth.
        
        @param frame The current stack frame.
        """
        self.__recursionDepth = 0
        while frame is not None:
            self.__recursionDepth += 1
            frame = frame.f_back
    
    def profile(self, frame, event, arg):
        """
        Public method used to trace some stuff independent of the debugger
        trace function.
        
        @param frame current stack frame.
        @param event trace event (string)
        @param arg arguments
        @exception RuntimeError raised to indicate too many recursions
        """
        if event == 'return':
            self.cFrame = frame.f_back
            self.__recursionDepth -= 1
            self.__sendCallTrace(event, frame, self.cFrame)
        elif event == 'call':
            self.__sendCallTrace(event, self.cFrame, frame)
            self.cFrame = frame
            self.__recursionDepth += 1
            if self.__recursionDepth > gRecursionLimit:
                raise RuntimeError(
                    'maximum recursion depth exceeded\n'
                    '(offending frame is two down the stack)')
    
    def __sendCallTrace(self, event, fromFrame, toFrame):
        """
        Private method to send a call/return trace.
        
        @param event trace event (string)
        @param fromFrame originating frame (frame)
        @param toFrame destination frame (frame)
        """
        if self._dbgClient.callTraceEnabled:
            if (not self.__skipFrame(fromFrame) and
                    not self.__skipFrame(toFrame)):
                if event in ["call", "return"]:
                    fr = fromFrame
                    fromStr = "{0}:{1}:{2}".format(
                        self._dbgClient.absPath(self.fix_frame_filename(fr)),
                        fr.f_lineno,
                        fr.f_code.co_name)
                    fr = toFrame
                    toStr = "{0}:{1}:{2}".format(
                        self._dbgClient.absPath(self.fix_frame_filename(fr)),
                        fr.f_lineno,
                        fr.f_code.co_name)
                    self._dbgClient.write("{0}{1}@@{2}@@{3}\n".format(
                        CallTrace, event[0], fromStr, toStr))
    
    def trace_dispatch(self, frame, event, arg):
        """
        Public method reimplemented from bdb.py to do some special things.
        
        This specialty is to check the connection to the debug server
        for new events (i.e. new breakpoints) while we are going through
        the code.
        
        @param frame The current stack frame
        @type frame object
        @param event The trace event
        @type str
        @param arg The arguments
        @type depends on the previous event parameter
        @return local trace function
        @rtype trace function or None
        @exception bdb.BdbQuit
        """
        if self.quitting:
            return  # None
        
        # give the client a chance to push through new break points.
        if self.eventPollFlag:
            self._dbgClient.eventPoll()
            self.eventPollFlag = False
        
        if event == 'line':
            if self.stop_here(frame) or self.break_here(frame):
                self.user_line(frame)
                if self.quitting:
                    raise bdb.BdbQuit
            return
        
        if event == 'call':
            if self.botframe is None:
                # First call of dispatch since reset()
                # (CT) Note that this may also be None!
                self.botframe = frame.f_back
                return self.trace_dispatch
            
            if not (self.stop_here(frame) or
                    self.break_anywhere(frame) or
                    Watch.watches != []):
                # No need to trace this function
                return
            if self.quitting:
                raise bdb.BdbQuit
            return self.trace_dispatch
        
        if event == 'return':
            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 & CO_GENERATOR:
                    return
                # The program has finished if we have just left the first frame
                if frame == self._dbgClient.mainFrame and \
                        self._mainThread:
                    atexit._run_exitfuncs()
                    self._dbgClient.progTerminated(arg)
                elif frame is not self.stepFrame:
                    self.stepFrame = None
                    self.user_line(frame)
                    
                if self.quitting and not self._dbgClient.passive:
                    raise bdb.BdbQuit
            return
        
        if event == 'exception':
            if not self.__skipFrame(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 & CO_GENERATOR and
                        arg[0] is StopIteration and arg[2] is None):
                    self.user_exception(frame, arg)
                    if self.quitting:
                        raise bdb.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 & CO_GENERATOR and
                    arg[0] in (StopIteration, GeneratorExit)):
                self.user_exception(frame, arg)
                if self.quitting:
                    raise bdb.BdbQuit
            return

        if event == 'c_call':
            return
        if event == 'c_exception':
            return
        if event == 'c_return':
            return
        print('bdb.Bdb.dispatch: unknown debugging event: ', repr(event))   # __IGNORE_WARNING__
        return self.trace_dispatch

    def set_trace(self, frame=None):
        """
        Public method reimplemented from bdb.py to do some special setup.
        
        @param frame frame to start debugging from
        """
        bdb.Bdb.set_trace(self, frame)
        sys.setprofile(self.profile)
    
    def set_continue(self, special):
        """
        Public method reimplemented from bdb.py to always get informed of
        exceptions.
        
        @param special flag indicating a special continue operation
        """
        # Modified version of the one found in bdb.py
        # Here we only set a new stop frame if it is a normal continue.
        if not special:
            self._set_stopinfo(self.botframe, None)
        else:
            self._set_stopinfo(self.stopframe, None)

    def set_quit(self):
        """
        Public method to quit.
        
        It wraps call to bdb to clear the current frame properly.
        """
        self.currentFrame = None
        sys.setprofile(None)
        bdb.Bdb.set_quit(self)
    
    def fix_frame_filename(self, frame):
        """
        Public method used to fixup the filename for a given frame.
        
        The logic employed here is that if a module was loaded
        from a .pyc file, then the correct .py to operate with
        should be in the same path as the .pyc. The reason this
        logic is needed is that when a .pyc file is generated, the
        filename embedded and thus what is readable in the code object
        of the frame object is the fully qualified filepath when the
        pyc is generated. If files are moved from machine to machine
        this can break debugging as the .pyc will refer to the .py
        on the original machine. Another case might be sharing
        code over a network... This logic deals with that.
        
        @param frame the frame object
        @type frame object
        @return fixed up file name
        @rtype str
        """
        # get module name from __file__
        fn = frame.f_globals.get('__file__')
        try:
            return self._fnCache[fn]
        except KeyError:
            if fn and fn != frame.f_code.co_filename:
                absFilename = os.path.abspath(fn)
                if absFilename.endswith(('.pyc', '.pyo')):
                    fixedName = absFilename[:-1]
                    if not os.path.exists(fixedName):
                        fixedName = absFilename
                else:
                    fixedName = absFilename
            else:
                fixedName = frame.f_code.co_filename
            # update cache
            self._fnCache[fn] = fixedName
            return fixedName

    def break_here(self, frame):
        """
        Public method reimplemented from bdb.py to fix the filename from the
        frame.
        
        See fix_frame_filename for more info.
        
        @param frame the frame object
        @type frame object
        @return flag indicating the break status
        @rtype bool
        """
        filename = self.fix_frame_filename(frame)
        if (filename, frame.f_lineno) in Breakpoint.breaks:
            bp, flag = Breakpoint.effectiveBreak(
                filename, frame.f_lineno, frame)
            if bp:
                # flag says ok to delete temp. bp
                if flag and bp.temporary:
                    self.__do_clearBreak(filename, frame.f_lineno)
                return True
        
        if Watch.watches != []:
            bp, flag = Watch.effectiveWatch(frame)
            if bp:
                # flag says ok to delete temp. watch
                if flag and bp.temporary:
                    self.__do_clearWatch(bp.cond)
                return True
        
        return False

    def break_anywhere(self, frame):
        """
        Public method reimplemented from bdb.py to do some special things.
        
        These speciality is to fix the filename from the frame
        (see fix_frame_filename for more info).
        
        @param frame the frame object
        @param frame object
        @return flag indicating the break status
        @rtype bool
        """
        return self.fix_frame_filename(frame) in Breakpoint.breakInFile

    def __do_clearBreak(self, filename, lineno):
        """
        Private method called to clear a temporary breakpoint.
        
        @param filename name of the file the bp belongs to
        @type str
        @param lineno linenumber of the bp
        @type int
        """
        Breakpoint.clear_break(filename, lineno)
        self._dbgClient.write('%s%s,%d\n' % (ResponseClearBreak, filename,
                                             lineno))

    def __do_clearWatch(self, cond):
        """
        Private method called to clear a temporary watch expression.
        
        @param cond expression of the watch expression to be cleared
        @type str
        """
        Watch.clear_watch(cond)
        self._dbgClient.write('%s%s\n' % (ResponseClearWatch, cond))

    def getStack(self):
        """
        Public method to get the stack.
        
        @return list of lists with file name (string), line number (integer)
            and function name (string)
        """
        fr = self.cFrame
        stack = []
        while fr is not None:
            fname = self._dbgClient.absPath(self.fix_frame_filename(fr))
            if not fname.startswith("<"):
                fline = fr.f_lineno
                ffunc = fr.f_code.co_name
                
                if ffunc == '?':
                    ffunc = ''
                
                if ffunc and not ffunc.startswith("<"):
                    argInfo = getargvalues(fr)
                    try:
                        fargs = formatargvalues(
                            argInfo.args, argInfo.varargs,
                            argInfo.keywords, argInfo.locals)
                    except Exception:
                        fargs = ""
                else:
                    fargs = ""
                
                stack.append([fname, fline, ffunc, fargs])
            
            if fr == self._dbgClient.mainFrame:
                fr = None
            else:
                fr = fr.f_back
        
        return stack
    
    def user_line(self, frame):
        """
        Public method reimplemented to handle the program about to execute a
        particular line.
        
        @param frame the frame object
        """
        line = frame.f_lineno

        # We never stop on line 0.
        if line == 0:
            return

        fn = self._dbgClient.absPath(self.fix_frame_filename(frame))

        # See if we are skipping at the start of a newly loaded program.
        if self._dbgClient.mainFrame is None:
            if fn != self._dbgClient.getRunning():
                return
            fr = frame
            while (fr is not None and
                    fr.f_code != self._dbgClient.handleLine.__code__):
                self._dbgClient.mainFrame = fr
                fr = fr.f_back

        self.currentFrame = frame
        
        fr = frame
        stack = []
        while fr is not None:
            # Reset the trace function so we can be sure
            # to trace all functions up the stack... This gets around
            # problems where an exception/breakpoint has occurred
            # but we had disabled tracing along the way via a None
            # return from dispatch_call
            fr.f_trace = self.trace_dispatch
            fname = self._dbgClient.absPath(self.fix_frame_filename(fr))
            if not fname.startswith("<"):
                fline = fr.f_lineno
                ffunc = fr.f_code.co_name
                
                if ffunc == '?':
                    ffunc = ''
                
                if ffunc and not ffunc.startswith("<"):
                    argInfo = getargvalues(fr)
                    try:
                        fargs = formatargvalues(
                            argInfo.args, argInfo.varargs,
                            argInfo.keywords, argInfo.locals)
                    except Exception:
                        fargs = ""
                else:
                    fargs = ""
                
                stack.append([fname, fline, ffunc, fargs])
            
            if fr == self._dbgClient.mainFrame:
                fr = None
            else:
                fr = fr.f_back
        
        self.__isBroken = True
        
        self._dbgClient.write('{0}{1}\n'.format(ResponseLine, str(stack)))
        self._dbgClient.eventLoop()
        
        self.__isBroken = False

    def user_exception(self, frame, excinfo, unhandled=False):
        """
        Public method reimplemented to report an exception to the debug server.
        
        @param frame the frame object
        @param excinfo information about the exception
        @param unhandled flag indicating an uncaught exception
        """
        exctype, excval, exctb = excinfo
        
        if exctype in [GeneratorExit, StopIteration]:
            # ignore these
            return
        
        if exctype in [SystemExit, bdb.BdbQuit]:
            atexit._run_exitfuncs()
            if excval is None:
                excval = 0
            elif isinstance(excval, str):
                self._dbgClient.write(excval)
                excval = 1
            elif isinstance(excval, bytes):
                self._dbgClient.write(excval.decode())
                excval = 1
            if isinstance(excval, int):
                self._dbgClient.progTerminated(excval)
            else:
                self._dbgClient.progTerminated(excval.code)
            return
        
        if exctype in [SyntaxError, IndentationError]:
            try:
                message = str(excval)
                filename = excval.filename
                linenr = excval.lineno
                charnr = excval.offset
            except (AttributeError, ValueError):
                exclist = []
                realSyntaxError = True
            else:
                exclist = [message, [filename, linenr, charnr]]
                realSyntaxError = os.path.exists(filename)
            
            if realSyntaxError:
                self._dbgClient.write("{0}{1}\n".format(
                    ResponseSyntax, str(exclist)))
                self._dbgClient.eventLoop()
                return
        
        exctype = self.__extractExceptionName(exctype)
        
        if excval is None:
            excval = ''
        
        if unhandled:
            exctypetxt = "unhandled {0!s}".format(str(exctype))
        else:
            exctypetxt = str(exctype)
        try:
            exclist = [exctypetxt, str(excval)]
        except TypeError:
            exclist = [exctypetxt, str(excval)]
        
        if exctb:
            frlist = self.__extract_stack(exctb)
            frlist.reverse()
            
            self.currentFrame = frlist[0]
            
            for fr in frlist:
                filename = self._dbgClient.absPath(self.fix_frame_filename(fr))
                
                if os.path.basename(filename).startswith("DebugClient") or \
                   os.path.basename(filename) == "bdb.py":
                    break
                
                linenr = fr.f_lineno
                ffunc = fr.f_code.co_name
                
                if ffunc == '?':
                    ffunc = ''
                
                if ffunc and not ffunc.startswith("<"):
                    argInfo = getargvalues(fr)
                    try:
                        fargs = formatargvalues(
                            argInfo.args, argInfo.varargs,
                            argInfo.keywords, argInfo.locals)
                    except Exception:
                        fargs = ""
                else:
                    fargs = ""
                
                exclist.append([filename, linenr, ffunc, fargs])
        
        self._dbgClient.write("{0}{1}\n".format(
            ResponseException, str(exclist)))
        
        if exctb is None:
            return
        
        self._dbgClient.eventLoop()
    
    def __extractExceptionName(self, exctype):
        """
        Private method to extract the exception name given the exception
        type object.
        
        @param exctype type of the exception
        @return exception name (string)
        """
        return str(exctype).replace("<class '", "").replace("'>", "")
    
    def __extract_stack(self, exctb):
        """
        Private member to return a list of stack frames.
        
        @param exctb exception traceback
        @return list of stack frames
        """
        tb = exctb
        stack = []
        while tb is not None:
            stack.append(tb.tb_frame)
            tb = tb.tb_next
        tb = None
        return stack

    def stop_here(self, frame):
        """
        Public method reimplemented to filter out debugger files.
        
        Tracing is turned off for files that are part of the
        debugger that are called from the application being debugged.
        
        @param frame the frame object
        @return flag indicating whether the debugger should stop here
        """
        if self.__skipFrame(frame):
            return False
        
        return bdb.Bdb.stop_here(self, frame)

    def tracePythonLibs(self, enable):
        """
        Public method to update the settings to trace into Python libraries.
        
        @param enable flag to debug into Python libraries
        @type int
        """
        pathsToSkip = list(self.pathsToSkip)
        # don't trace into Python library?
        if enable:
            pathsToSkip = [x for x in pathsToSkip if not x.endswith(
                ("site-packages", "dist-packages", self.lib))]
        else:
            pathsToSkip.append(self.lib)
            localLib = [x for x in sys.path if x.endswith(("site-packages",
                        "dist-packages")) and not x.startswith(self.lib)]
            pathsToSkip.extend(localLib)
        
        self.pathsToSkip = tuple(pathsToSkip)

    def __skipFrame(self, frame):
        """
        Private method to filter out debugger files.
        
        Tracing is turned off for files that are part of the
        debugger that are called from the application being debugged.
        
        @param frame the frame object
        @type frame object
        @return flag indicating whether the debugger should skip this frame
        @rtype bool
        """
        try:
            return self.filesToSkip[frame.f_code.co_filename]
        except KeyError:
            ret = frame.f_code.co_filename.startswith(self.pathsToSkip)
            self.filesToSkip[frame.f_code.co_filename] = ret
            return ret
        except AttributeError:
            # if frame is None
            return True
    
    def isBroken(self):
        """
        Public method to return the broken state of the debugger.
        
        @return flag indicating the broken state
        @rtype bool
        """
        return self.__isBroken

#
# eflag: noqa = M702