Source code for pdb

#! /usr/bin/env python3

The Python Debugger Pdb

To use the debugger in its simplest form:

        >>> import pdb
        >>>'<a statement>')

The debugger's prompt is '(Pdb) '.  This will stop in the first
function call in <a statement>.

Alternatively, if a statement terminated with an unhandled exception,
you can use pdb's post-mortem facility to inspect the contents of the

        >>> <a statement>
        <exception traceback>
        >>> import pdb

The commands recognized by the debugger are listed in the next
section.  Most can be abbreviated as indicated; e.g., h(elp) means
that 'help' can be typed as 'h' or 'help' (but not as 'he' or 'hel',
nor as 'H' or 'Help' or 'HELP').  Optional arguments are enclosed in
square brackets.  Alternatives in the command syntax are separated
by a vertical bar (|).

A blank line repeats the previous command literally, except for
'list', where it lists the next 11 lines.

Commands that the debugger doesn't recognize are assumed to be Python
statements and are executed in the context of the program being
debugged.  Python statements can also be prefixed with an exclamation
point ('!').  This is a powerful way to inspect the program being
debugged; it is even possible to change variables or call functions.
When an exception occurs in such a statement, the exception name is
printed but the debugger's state is not changed.

The debugger supports aliases, which can save typing.  And aliases can
have parameters (see the alias help entry) which allows one a certain
level of adaptability to the context under examination.

Multiple commands may be entered on a single line, separated by the
pair ';;'.  No intelligence is applied to separating the commands; the
input is split at the first ';;', even if it is in the middle of a
quoted string.

If a file ".pdbrc" exists in your home directory or in the current
directory, it is read in and executed as if it had been typed at the
debugger prompt.  This is particularly useful for aliases.  If both
files exist, the one in the home directory is read first and aliases
defined there can be overridden by the local file.  This behavior can be
disabled by passing the "readrc=False" argument to the Pdb constructor.

Aside from aliases, the debugger is not directly programmable; but it
is implemented as a class from which you can derive your own debugger
class, which you can make as fancy as you like.

Debugger commands

# NOTE: the actual command documentation is collected from docstrings of the
# commands and is appended to __doc__ after the class has been defined.

import os
import re
import sys
import cmd
import bdb
import dis
import code
import glob
import pprint
import signal
import inspect
import traceback
import linecache

class Restart(Exception):
    """Causes a debugger to be restarted for the debugged python program."""

__all__ = ["run", "pm", "Pdb", "runeval", "runctx", "runcall", "set_trace",
           "post_mortem", "help"]

def find_function(funcname, filename):
    cre = re.compile(r'def\s+%s\s*[(]' % re.escape(funcname))
        fp = open(filename)
    except OSError:
        return None
    # consumer of this info expects the first line to be 1
    with fp:
        for lineno, line in enumerate(fp, start=1):
            if cre.match(line):
                return funcname, filename, lineno
    return None

def getsourcelines(obj):
    lines, lineno = inspect.findsource(obj)
    if inspect.isframe(obj) and obj.f_globals is obj.f_locals:
        # must be a module frame: do not try to cut a block out of it
        return lines, 1
    elif inspect.ismodule(obj):
        return lines, 1
    return inspect.getblock(lines[lineno:]), lineno+1

def lasti2lineno(code, lasti):
    linestarts = list(dis.findlinestarts(code))
    for i, lineno in linestarts:
        if lasti >= i:
            return lineno
    return 0

class _rstr(str):
    """String that doesn't quote its repr."""
    def __repr__(self):
        return self

# Interaction prompt line will separate file and call info from code
# text using value of line_prefix string.  A newline and arrow may
# be to your liking.  You can set it once pdb is imported using the
# command "pdb.line_prefix = '\n% '".
# line_prefix = ': '    # Use this to get the old situation back
line_prefix = '\n-> '   # Probably a better default

[docs]class Pdb(bdb.Bdb, cmd.Cmd): _previous_sigint_handler = None def __init__(self, completekey='tab', stdin=None, stdout=None, skip=None, nosigint=False, readrc=True): bdb.Bdb.__init__(self, skip=skip) cmd.Cmd.__init__(self, completekey, stdin, stdout) if stdout: self.use_rawinput = 0 self.prompt = '(Pdb) ' self.aliases = {} self.displaying = {} self.mainpyfile = '' self._wait_for_mainpyfile = False self.tb_lineno = {} # Try to load readline if it exists try: import readline # remove some common file name delimiters readline.set_completer_delims(' \t\n`@#$%^&*()=+[{]}\\|;:\'",<>?') except ImportError: pass self.allow_kbdint = False self.nosigint = nosigint # Read $HOME/.pdbrc and ./.pdbrc self.rcLines = [] if readrc: if 'HOME' in os.environ: envHome = os.environ['HOME'] try: with open(os.path.join(envHome, ".pdbrc")) as rcFile: self.rcLines.extend(rcFile) except OSError: pass try: with open(".pdbrc") as rcFile: self.rcLines.extend(rcFile) except OSError: pass self.commands = {} # associates a command list to breakpoint numbers self.commands_doprompt = {} # for each bp num, tells if the prompt # must be disp. after execing the cmd list self.commands_silent = {} # for each bp num, tells if the stack trace # must be disp. after execing the cmd list self.commands_defining = False # True while in the process of defining # a command list self.commands_bnum = None # The breakpoint number for which we are # defining a list def sigint_handler(self, signum, frame): if self.allow_kbdint: raise KeyboardInterrupt self.message("\nProgram interrupted. (Use 'cont' to resume).") self.set_step() self.set_trace(frame) def reset(self): bdb.Bdb.reset(self) self.forget() def forget(self): self.lineno = None self.stack = [] self.curindex = 0 self.curframe = None self.tb_lineno.clear() def setup(self, f, tb): self.forget() self.stack, self.curindex = self.get_stack(f, tb) while tb: # when setting up post-mortem debugging with a traceback, save all # the original line numbers to be displayed along the current line # numbers (which can be different, e.g. due to finally clauses) lineno = lasti2lineno(tb.tb_frame.f_code, tb.tb_lasti) self.tb_lineno[tb.tb_frame] = lineno tb = tb.tb_next self.curframe = self.stack[self.curindex][0] # The f_locals dictionary is updated from the actual frame # locals whenever the .f_locals accessor is called, so we # cache it here to ensure that modifications are not overwritten. self.curframe_locals = self.curframe.f_locals return self.execRcLines() # Can be executed earlier than 'setup' if desired def execRcLines(self): if not self.rcLines: return # local copy because of recursion rcLines = self.rcLines rcLines.reverse() # execute every line only once self.rcLines = [] while rcLines: line = rcLines.pop().strip() if line and line[0] != '#': if self.onecmd(line): # if onecmd returns True, the command wants to exit # from the interaction, save leftover rc lines # to execute before next interaction self.rcLines += reversed(rcLines) return True # Override Bdb methods 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.""" if self._wait_for_mainpyfile: return if self.stop_here(frame): self.message('--Call--') self.interaction(frame, None) def user_line(self, frame): """This function is called when we stop or break at this line.""" if self._wait_for_mainpyfile: if (self.mainpyfile != self.canonic(frame.f_code.co_filename) or frame.f_lineno <= 0): return self._wait_for_mainpyfile = False if self.bp_commands(frame): self.interaction(frame, None) def bp_commands(self, frame): """Call every command that was set for the current active breakpoint (if there is one). Returns True if the normal interaction function must be called, False otherwise.""" # self.currentbp is set in bdb in Bdb.break_here if a breakpoint was hit if getattr(self, "currentbp", False) and \ self.currentbp in self.commands: currentbp = self.currentbp self.currentbp = 0 lastcmd_back = self.lastcmd self.setup(frame, None) for line in self.commands[currentbp]: self.onecmd(line) self.lastcmd = lastcmd_back if not self.commands_silent[currentbp]: self.print_stack_entry(self.stack[self.curindex]) if self.commands_doprompt[currentbp]: self._cmdloop() self.forget() return return 1 def user_return(self, frame, return_value): """This function is called when a return trap is set here.""" if self._wait_for_mainpyfile: return frame.f_locals['__return__'] = return_value self.message('--Return--') self.interaction(frame, None) def user_exception(self, frame, exc_info): """This function is called if an exception occurs, but only if we are to stop at or just below this level.""" if self._wait_for_mainpyfile: return exc_type, exc_value, exc_traceback = exc_info frame.f_locals['__exception__'] = exc_type, exc_value # An 'Internal StopIteration' exception is an exception debug event # issued by the interpreter when handling a subgenerator run with # 'yield from' or a generator controlled by a for loop. No exception has # actually occurred in this case. The debugger uses this debug event to # stop when the debuggee is returning from such generators. prefix = 'Internal ' if (not exc_traceback and exc_type is StopIteration) else '' self.message('%s%s' % (prefix, traceback.format_exception_only(exc_type, exc_value)[-1].strip())) self.interaction(frame, exc_traceback) # General interaction function def _cmdloop(self): while True: try: # keyboard interrupts allow for an easy way to cancel # the current command, so allow them during interactive input self.allow_kbdint = True self.cmdloop() self.allow_kbdint = False break except KeyboardInterrupt: self.message('--KeyboardInterrupt--') # Called before loop, handles display expressions def preloop(self): displaying = self.displaying.get(self.curframe) if displaying: for expr, oldvalue in displaying.items(): newvalue = self._getval_except(expr) # check for identity first; this prevents custom __eq__ to # be called at every loop, and also prevents instances whose # fields are changed to be displayed if newvalue is not oldvalue and newvalue != oldvalue: displaying[expr] = newvalue self.message('display %s: %r [old: %r]' % (expr, newvalue, oldvalue)) def interaction(self, frame, traceback): # Restore the previous signal handler at the Pdb prompt. if Pdb._previous_sigint_handler: signal.signal(signal.SIGINT, Pdb._previous_sigint_handler) Pdb._previous_sigint_handler = None if self.setup(frame, traceback): # no interaction desired at this time (happens if .pdbrc contains # a command like "continue") self.forget() return self.print_stack_entry(self.stack[self.curindex]) self._cmdloop() self.forget() def displayhook(self, obj): """Custom displayhook for the exec in default(), which prevents assignment of the _ variable in the builtins. """ # reproduce the behavior of the standard displayhook, not printing None if obj is not None: self.message(repr(obj)) def default(self, line): if line[:1] == '!': line = line[1:] locals = self.curframe_locals globals = self.curframe.f_globals try: code = compile(line + '\n', '<stdin>', 'single') save_stdout = sys.stdout save_stdin = sys.stdin save_displayhook = sys.displayhook try: sys.stdin = self.stdin sys.stdout = self.stdout sys.displayhook = self.displayhook exec(code, globals, locals) finally: sys.stdout = save_stdout sys.stdin = save_stdin sys.displayhook = save_displayhook except: exc_info = sys.exc_info()[:2] self.error(traceback.format_exception_only(*exc_info)[-1].strip()) def precmd(self, line): """Handle alias expansion and ';;' separator.""" if not line.strip(): return line args = line.split() while args[0] in self.aliases: line = self.aliases[args[0]] ii = 1 for tmpArg in args[1:]: line = line.replace("%" + str(ii), tmpArg) ii += 1 line = line.replace("%*", ' '.join(args[1:])) args = line.split() # split into ';;' separated commands # unless it's an alias command if args[0] != 'alias': marker = line.find(';;') if marker >= 0: # queue up everything after marker next = line[marker+2:].lstrip() self.cmdqueue.append(next) line = line[:marker].rstrip() return line def onecmd(self, line): """Interpret the argument as though it had been typed in response to the prompt. Checks whether this line is typed at the normal prompt or in a breakpoint command list definition. """ if not self.commands_defining: return cmd.Cmd.onecmd(self, line) else: return self.handle_command_def(line) def handle_command_def(self, line): """Handles one command line during command list definition.""" cmd, arg, line = self.parseline(line) if not cmd: return if cmd == 'silent': self.commands_silent[self.commands_bnum] = True return # continue to handle other cmd def in the cmd list elif cmd == 'end': self.cmdqueue = [] return 1 # end of cmd list cmdlist = self.commands[self.commands_bnum] if arg: cmdlist.append(cmd+' '+arg) else: cmdlist.append(cmd) # Determine if we must stop try: func = getattr(self, 'do_' + cmd) except AttributeError: func = self.default # one of the resuming commands if func.__name__ in self.commands_resuming: self.commands_doprompt[self.commands_bnum] = False self.cmdqueue = [] return 1 return # interface abstraction functions def message(self, msg): print(msg, file=self.stdout) def error(self, msg): print('***', msg, file=self.stdout) # Generic completion functions. Individual complete_foo methods can be # assigned below to one of these functions. def _complete_location(self, text, line, begidx, endidx): # Complete a file/module/function location for break/tbreak/clear. if line.strip().endswith((':', ',')): # Here comes a line number or a condition which we can't complete. return [] # First, try to find matching functions (i.e. expressions). try: ret = self._complete_expression(text, line, begidx, endidx) except Exception: ret = [] # Then, try to complete file names as well. globs = glob.glob(text + '*') for fn in globs: if os.path.isdir(fn): ret.append(fn + '/') elif os.path.isfile(fn) and fn.lower().endswith(('.py', '.pyw')): ret.append(fn + ':') return ret def _complete_bpnumber(self, text, line, begidx, endidx): # Complete a breakpoint number. (This would be more helpful if we could # display additional info along with the completions, such as file/line # of the breakpoint.) return [str(i) for i, bp in enumerate(bdb.Breakpoint.bpbynumber) if bp is not None and str(i).startswith(text)] def _complete_expression(self, text, line, begidx, endidx): # Complete an arbitrary expression. if not self.curframe: return [] # Collect globals and locals. It is usually not really sensible to also # complete builtins, and they clutter the namespace quite heavily, so we # leave them out. ns = self.curframe.f_globals.copy() ns.update(self.curframe_locals) if '.' in text: # Walk an attribute chain up to the last part, similar to what # rlcompleter does. This will bail if any of the parts are not # simple attribute access, which is what we want. dotted = text.split('.') try: obj = ns[dotted[0]] for part in dotted[1:-1]: obj = getattr(obj, part) except (KeyError, AttributeError): return [] prefix = '.'.join(dotted[:-1]) + '.' return [prefix + n for n in dir(obj) if n.startswith(dotted[-1])] else: # Complete a simple name. return [n for n in ns.keys() if n.startswith(text)] # Command definitions, called by cmdloop() # The argument is the remaining string on the command line # Return true to exit from the command loop def do_commands(self, arg): """commands [bpnumber] (com) ... (com) end (Pdb) Specify a list of commands for breakpoint number bpnumber. The commands themselves are entered on the following lines. Type a line containing just 'end' to terminate the commands. The commands are executed when the breakpoint is hit. To remove all commands from a breakpoint, type commands and follow it immediately with end; that is, give no commands. With no bpnumber argument, commands refers to the last breakpoint set. You can use breakpoint commands to start your program up again. Simply use the continue command, or step, or any other command that resumes execution. Specifying any command resuming execution (currently continue, step, next, return, jump, quit and their abbreviations) terminates the command list (as if that command was immediately followed by end). This is because any time you resume execution (even with a simple next or step), you may encounter another breakpoint -- which could have its own command list, leading to ambiguities about which list to execute. If you use the 'silent' command in the command list, the usual message about stopping at a breakpoint is not printed. This may be desirable for breakpoints that are to print a specific message and then continue. If none of the other commands print anything, you will see no sign that the breakpoint was reached. """ if not arg: bnum = len(bdb.Breakpoint.bpbynumber) - 1 else: try: bnum = int(arg) except: self.error("Usage: commands [bnum]\n ...\n end") return self.commands_bnum = bnum # Save old definitions for the case of a keyboard interrupt. if bnum in self.commands: old_command_defs = (self.commands[bnum], self.commands_doprompt[bnum], self.commands_silent[bnum]) else: old_command_defs = None self.commands[bnum] = [] self.commands_doprompt[bnum] = True self.commands_silent[bnum] = False prompt_back = self.prompt self.prompt = '(com) ' self.commands_defining = True try: self.cmdloop() except KeyboardInterrupt: # Restore old definitions. if old_command_defs: self.commands[bnum] = old_command_defs[0] self.commands_doprompt[bnum] = old_command_defs[1] self.commands_silent[bnum] = old_command_defs[2] else: del self.commands[bnum] del self.commands_doprompt[bnum] del self.commands_silent[bnum] self.error('command definition aborted, old commands restored') finally: self.commands_defining = False self.prompt = prompt_back complete_commands = _complete_bpnumber def do_break(self, arg, temporary = 0): """b(reak) [ ([filename:]lineno | function) [, condition] ] Without argument, list all breaks. With a line number argument, set a break at this line in the current file. With a function name, set a break at the first executable line of that function. If a second argument is present, it is a string specifying an expression which must evaluate to true before the breakpoint is honored. The line number may be prefixed with a filename and a colon, to specify a breakpoint in another file (probably one that hasn't been loaded yet). The file is searched for on sys.path; the .py suffix may be omitted. """ if not arg: if self.breaks: # There's at least one self.message("Num Type Disp Enb Where") for bp in bdb.Breakpoint.bpbynumber: if bp: self.message(bp.bpformat()) return # parse arguments; comma has lowest precedence # and cannot occur in filename filename = None lineno = None cond = None comma = arg.find(',') if comma > 0: # parse stuff after comma: "condition" cond = arg[comma+1:].lstrip() arg = arg[:comma].rstrip() # parse stuff before comma: [filename:]lineno | function colon = arg.rfind(':') funcname = None if colon >= 0: filename = arg[:colon].rstrip() f = self.lookupmodule(filename) if not f: self.error('%r not found from sys.path' % filename) return else: filename = f arg = arg[colon+1:].lstrip() try: lineno = int(arg) except ValueError: self.error('Bad lineno: %s' % arg) return else: # no colon; can be lineno or function try: lineno = int(arg) except ValueError: try: func = eval(arg, self.curframe.f_globals, self.curframe_locals) except: func = arg try: if hasattr(func, '__func__'): func = func.__func__ code = func.__code__ #use co_name to identify the bkpt (function names #could be aliased, but co_name is invariant) funcname = code.co_name lineno = code.co_firstlineno filename = code.co_filename except: # last thing to try (ok, filename, ln) = self.lineinfo(arg) if not ok: self.error('The specified object %r is not a function ' 'or was not found along sys.path.' % arg) return funcname = ok # ok contains a function name lineno = int(ln) if not filename: filename = self.defaultFile() # Check for reasonable breakpoint line = self.checkline(filename, lineno) if line: # now set the break point err = self.set_break(filename, line, temporary, cond, funcname) if err: self.error(err) else: bp = self.get_breaks(filename, line)[-1] self.message("Breakpoint %d at %s:%d" % (bp.number, bp.file, bp.line)) # To be overridden in derived debuggers def defaultFile(self): """Produce a reasonable default.""" filename = self.curframe.f_code.co_filename if filename == '<string>' and self.mainpyfile: filename = self.mainpyfile return filename do_b = do_break complete_break = _complete_location complete_b = _complete_location def do_tbreak(self, arg): """tbreak [ ([filename:]lineno | function) [, condition] ] Same arguments as break, but sets a temporary breakpoint: it is automatically deleted when first hit. """ self.do_break(arg, 1) complete_tbreak = _complete_location def lineinfo(self, identifier): failed = (None, None, None) # Input is identifier, may be in single quotes idstring = identifier.split("'") if len(idstring) == 1: # not in single quotes id = idstring[0].strip() elif len(idstring) == 3: # quoted id = idstring[1].strip() else: return failed if id == '': return failed parts = id.split('.') # Protection for derived debuggers if parts[0] == 'self': del parts[0] if len(parts) == 0: return failed # Best first guess at file to look at fname = self.defaultFile() if len(parts) == 1: item = parts[0] else: # More than one part. # First is module, second is method/class f = self.lookupmodule(parts[0]) if f: fname = f item = parts[1] answer = find_function(item, fname) return answer or failed def checkline(self, filename, lineno): """Check whether specified line seems to be executable. Return `lineno` if it is, 0 if not (e.g. a docstring, comment, blank line or EOF). Warning: testing is not comprehensive. """ # this method should be callable before starting debugging, so default # to "no globals" if there is no current frame globs = self.curframe.f_globals if hasattr(self, 'curframe') else None line = linecache.getline(filename, lineno, globs) if not line: self.message('End of file') return 0 line = line.strip() # Don't allow setting breakpoint at a blank line if (not line or (line[0] == '#') or (line[:3] == '"""') or line[:3] == "'''"): self.error('Blank or comment') return 0 return lineno def do_enable(self, arg): """enable bpnumber [bpnumber ...] Enables the breakpoints given as a space separated list of breakpoint numbers. """ args = arg.split() for i in args: try: bp = self.get_bpbynumber(i) except ValueError as err: self.error(err) else: bp.enable() self.message('Enabled %s' % bp) complete_enable = _complete_bpnumber def do_disable(self, arg): """disable bpnumber [bpnumber ...] Disables the breakpoints given as a space separated list of breakpoint numbers. Disabling a breakpoint means it cannot cause the program to stop execution, but unlike clearing a breakpoint, it remains in the list of breakpoints and can be (re-)enabled. """ args = arg.split() for i in args: try: bp = self.get_bpbynumber(i) except ValueError as err: self.error(err) else: bp.disable() self.message('Disabled %s' % bp) complete_disable = _complete_bpnumber def do_condition(self, arg): """condition bpnumber [condition] Set a new condition for the breakpoint, an expression which must evaluate to true before the breakpoint is honored. If condition is absent, any existing condition is removed; i.e., the breakpoint is made unconditional. """ args = arg.split(' ', 1) try: cond = args[1] except IndexError: cond = None try: bp = self.get_bpbynumber(args[0].strip()) except IndexError: self.error('Breakpoint number expected') except ValueError as err: self.error(err) else: bp.cond = cond if not cond: self.message('Breakpoint %d is now unconditional.' % bp.number) else: self.message('New condition set for breakpoint %d.' % bp.number) complete_condition = _complete_bpnumber def do_ignore(self, arg): """ignore bpnumber [count] Set the ignore count for the given breakpoint number. If count is omitted, the ignore count is set to 0. A breakpoint becomes active when the ignore count is zero. When non-zero, the count is decremented each time the breakpoint is reached and the breakpoint is not disabled and any associated condition evaluates to true. """ args = arg.split() try: count = int(args[1].strip()) except: count = 0 try: bp = self.get_bpbynumber(args[0].strip()) except IndexError: self.error('Breakpoint number expected') except ValueError as err: self.error(err) else: bp.ignore = count if count > 0: if count > 1: countstr = '%d crossings' % count else: countstr = '1 crossing' self.message('Will ignore next %s of breakpoint %d.' % (countstr, bp.number)) else: self.message('Will stop next time breakpoint %d is reached.' % bp.number) complete_ignore = _complete_bpnumber def do_clear(self, arg): """cl(ear) filename:lineno\ncl(ear) [bpnumber [bpnumber...]] With a space separated list of breakpoint numbers, clear those breakpoints. Without argument, clear all breaks (but first ask confirmation). With a filename:lineno argument, clear all breaks at that line in that file. """ if not arg: try: reply = input('Clear all breaks? ') except EOFError: reply = 'no' reply = reply.strip().lower() if reply in ('y', 'yes'): bplist = [bp for bp in bdb.Breakpoint.bpbynumber if bp] self.clear_all_breaks() for bp in bplist: self.message('Deleted %s' % bp) return if ':' in arg: # Make sure it works for "clear C:\foo\" i = arg.rfind(':') filename = arg[:i] arg = arg[i+1:] try: lineno = int(arg) except ValueError: err = "Invalid line number (%s)" % arg else: bplist = self.get_breaks(filename, lineno) err = self.clear_break(filename, lineno) if err: self.error(err) else: for bp in bplist: self.message('Deleted %s' % bp) return numberlist = arg.split() for i in numberlist: try: bp = self.get_bpbynumber(i) except ValueError as err: self.error(err) else: self.clear_bpbynumber(i) self.message('Deleted %s' % bp) do_cl = do_clear # 'c' is already an abbreviation for 'continue' complete_clear = _complete_location complete_cl = _complete_location def do_where(self, arg): """w(here) Print a stack trace, with the most recent frame at the bottom. An arrow indicates the "current frame", which determines the context of most commands. 'bt' is an alias for this command. """ self.print_stack_trace() do_w = do_where do_bt = do_where def _select_frame(self, number): assert 0 <= number < len(self.stack) self.curindex = number self.curframe = self.stack[self.curindex][0] self.curframe_locals = self.curframe.f_locals self.print_stack_entry(self.stack[self.curindex]) self.lineno = None def do_up(self, arg): """u(p) [count] Move the current frame count (default one) levels up in the stack trace (to an older frame). """ if self.curindex == 0: self.error('Oldest frame') return try: count = int(arg or 1) except ValueError: self.error('Invalid frame count (%s)' % arg) return if count < 0: newframe = 0 else: newframe = max(0, self.curindex - count) self._select_frame(newframe) do_u = do_up def do_down(self, arg): """d(own) [count] Move the current frame count (default one) levels down in the stack trace (to a newer frame). """ if self.curindex + 1 == len(self.stack): self.error('Newest frame') return try: count = int(arg or 1) except ValueError: self.error('Invalid frame count (%s)' % arg) return if count < 0: newframe = len(self.stack) - 1 else: newframe = min(len(self.stack) - 1, self.curindex + count) self._select_frame(newframe) do_d = do_down def do_until(self, arg): """unt(il) [lineno] Without argument, continue execution until the line with a number greater than the current one is reached. With a line number, continue execution until a line with a number greater or equal to that is reached. In both cases, also stop when the current frame returns. """ if arg: try: lineno = int(arg) except ValueError: self.error('Error in argument: %r' % arg) return if lineno <= self.curframe.f_lineno: self.error('"until" line number is smaller than current ' 'line number') return else: lineno = None self.set_until(self.curframe, lineno) return 1 do_unt = do_until def do_step(self, arg): """s(tep) Execute the current line, stop at the first possible occasion (either in a function that is called or in the current function). """ self.set_step() return 1 do_s = do_step def do_next(self, arg): """n(ext) Continue execution until the next line in the current function is reached or it returns. """ self.set_next(self.curframe) return 1 do_n = do_next def do_run(self, arg): """run [args...] Restart the debugged python program. If a string is supplied it is split with "shlex", and the result is used as the new sys.argv. History, breakpoints, actions and debugger options are preserved. "restart" is an alias for "run". """ if arg: import shlex argv0 = sys.argv[0:1] sys.argv = shlex.split(arg) sys.argv[:0] = argv0 # this is caught in the main debugger loop raise Restart do_restart = do_run def do_return(self, arg): """r(eturn) Continue execution until the current function returns. """ self.set_return(self.curframe) return 1 do_r = do_return def do_continue(self, arg): """c(ont(inue)) Continue execution, only stop when a breakpoint is encountered. """ if not self.nosigint: try: Pdb._previous_sigint_handler = \ signal.signal(signal.SIGINT, self.sigint_handler) except ValueError: # ValueError happens when do_continue() is invoked from # a non-main thread in which case we just continue without # SIGINT set. Would printing a message here (once) make # sense? pass self.set_continue() return 1 do_c = do_cont = do_continue def do_jump(self, arg): """j(ump) lineno Set the next line that will be executed. Only available in the bottom-most frame. This lets you jump back and execute code again, or jump forward to skip code that you don't want to run. It should be noted that not all jumps are allowed -- for instance it is not possible to jump into the middle of a for loop or out of a finally clause. """ if self.curindex + 1 != len(self.stack): self.error('You can only jump within the bottom frame') return try: arg = int(arg) except ValueError: self.error("The 'jump' command requires a line number") else: try: # Do the jump, fix up our copy of the stack, and display the # new position self.curframe.f_lineno = arg self.stack[self.curindex] = self.stack[self.curindex][0], arg self.print_stack_entry(self.stack[self.curindex]) except ValueError as e: self.error('Jump failed: %s' % e) do_j = do_jump def do_debug(self, arg): """debug code Enter a recursive debugger that steps through the code argument (which is an arbitrary expression or statement to be executed in the current environment). """ sys.settrace(None) globals = self.curframe.f_globals locals = self.curframe_locals p = Pdb(self.completekey, self.stdin, self.stdout) p.prompt = "(%s) " % self.prompt.strip() self.message("ENTERING RECURSIVE DEBUGGER") sys.call_tracing(, (arg, globals, locals)) self.message("LEAVING RECURSIVE DEBUGGER") sys.settrace(self.trace_dispatch) self.lastcmd = p.lastcmd complete_debug = _complete_expression def do_quit(self, arg): """q(uit)\nexit Quit from the debugger. The program being executed is aborted. """ self._user_requested_quit = True self.set_quit() return 1 do_q = do_quit do_exit = do_quit def do_EOF(self, arg): """EOF Handles the receipt of EOF as a command. """ self.message('') self._user_requested_quit = True self.set_quit() return 1 def do_args(self, arg): """a(rgs) Print the argument list of the current function. """ co = self.curframe.f_code dict = self.curframe_locals n = co.co_argcount if co.co_flags & 4: n = n+1 if co.co_flags & 8: n = n+1 for i in range(n): name = co.co_varnames[i] if name in dict: self.message('%s = %r' % (name, dict[name])) else: self.message('%s = *** undefined ***' % (name,)) do_a = do_args def do_retval(self, arg): """retval Print the return value for the last return of a function. """ if '__return__' in self.curframe_locals: self.message(repr(self.curframe_locals['__return__'])) else: self.error('Not yet returned!') do_rv = do_retval def _getval(self, arg): try: return eval(arg, self.curframe.f_globals, self.curframe_locals) except: exc_info = sys.exc_info()[:2] self.error(traceback.format_exception_only(*exc_info)[-1].strip()) raise def _getval_except(self, arg, frame=None): try: if frame is None: return eval(arg, self.curframe.f_globals, self.curframe_locals) else: return eval(arg, frame.f_globals, frame.f_locals) except: exc_info = sys.exc_info()[:2] err = traceback.format_exception_only(*exc_info)[-1].strip() return _rstr('** raised %s **' % err) def do_p(self, arg): """p expression Print the value of the expression. """ try: self.message(repr(self._getval(arg))) except: pass def do_pp(self, arg): """pp expression Pretty-print the value of the expression. """ try: self.message(pprint.pformat(self._getval(arg))) except: pass complete_print = _complete_expression complete_p = _complete_expression complete_pp = _complete_expression def do_list(self, arg): """l(ist) [first [,last] | .] List source code for the current file. Without arguments, list 11 lines around the current line or continue the previous listing. With . as argument, list 11 lines around the current line. With one argument, list 11 lines starting at that line. With two arguments, list the given range; if the second argument is less than the first, it is a count. The current line in the current frame is indicated by "->". If an exception is being debugged, the line where the exception was originally raised or propagated is indicated by ">>", if it differs from the current line. """ self.lastcmd = 'list' last = None if arg and arg != '.': try: if ',' in arg: first, last = arg.split(',') first = int(first.strip()) last = int(last.strip()) if last < first: # assume it's a count last = first + last else: first = int(arg.strip()) first = max(1, first - 5) except ValueError: self.error('Error in argument: %r' % arg) return elif self.lineno is None or arg == '.': first = max(1, self.curframe.f_lineno - 5) else: first = self.lineno + 1 if last is None: last = first + 10 filename = self.curframe.f_code.co_filename breaklist = self.get_file_breaks(filename) try: lines = linecache.getlines(filename, self.curframe.f_globals) self._print_lines(lines[first-1:last], first, breaklist, self.curframe) self.lineno = min(last, len(lines)) if len(lines) < last: self.message('[EOF]') except KeyboardInterrupt: pass do_l = do_list def do_longlist(self, arg): """longlist | ll List the whole source code for the current function or frame. """ filename = self.curframe.f_code.co_filename breaklist = self.get_file_breaks(filename) try: lines, lineno = getsourcelines(self.curframe) except OSError as err: self.error(err) return self._print_lines(lines, lineno, breaklist, self.curframe) do_ll = do_longlist def do_source(self, arg): """source expression Try to get source code for the given object and display it. """ try: obj = self._getval(arg) except: return try: lines, lineno = getsourcelines(obj) except (OSError, TypeError) as err: self.error(err) return self._print_lines(lines, lineno) complete_source = _complete_expression def _print_lines(self, lines, start, breaks=(), frame=None): """Print a range of lines.""" if frame: current_lineno = frame.f_lineno exc_lineno = self.tb_lineno.get(frame, -1) else: current_lineno = exc_lineno = -1 for lineno, line in enumerate(lines, start): s = str(lineno).rjust(3) if len(s) < 4: s += ' ' if lineno in breaks: s += 'B' else: s += ' ' if lineno == current_lineno: s += '->' elif lineno == exc_lineno: s += '>>' self.message(s + '\t' + line.rstrip()) def do_whatis(self, arg): """whatis arg Print the type of the argument. """ try: value = self._getval(arg) except: # _getval() already printed the error return code = None # Is it a function? try: code = value.__code__ except Exception: pass if code: self.message('Function %s' % code.co_name) return # Is it an instance method? try: code = value.__func__.__code__ except Exception: pass if code: self.message('Method %s' % code.co_name) return # Is it a class? if value.__class__ is type: self.message('Class %s.%s' % (value.__module__, value.__qualname__)) return # None of the above... self.message(type(value)) complete_whatis = _complete_expression def do_display(self, arg): """display [expression] Display the value of the expression if it changed, each time execution stops in the current frame. Without expression, list all display expressions for the current frame. """ if not arg: self.message('Currently displaying:') for item in self.displaying.get(self.curframe, {}).items(): self.message('%s: %r' % item) else: val = self._getval_except(arg) self.displaying.setdefault(self.curframe, {})[arg] = val self.message('display %s: %r' % (arg, val)) complete_display = _complete_expression def do_undisplay(self, arg): """undisplay [expression] Do not display the expression any more in the current frame. Without expression, clear all display expressions for the current frame. """ if arg: try: del self.displaying.get(self.curframe, {})[arg] except KeyError: self.error('not displaying %s' % arg) else: self.displaying.pop(self.curframe, None) def complete_undisplay(self, text, line, begidx, endidx): return [e for e in self.displaying.get(self.curframe, {}) if e.startswith(text)] def do_interact(self, arg): """interact Start an interactive interpreter whose global namespace contains all the (global and local) names found in the current scope. """ ns = self.curframe.f_globals.copy() ns.update(self.curframe_locals) code.interact("*interactive*", local=ns) def do_alias(self, arg): """alias [name [command [parameter parameter ...] ]] Create an alias called 'name' that executes 'command'. The command must *not* be enclosed in quotes. Replaceable parameters can be indicated by %1, %2, and so on, while %* is replaced by all the parameters. If no command is given, the current alias for name is shown. If no name is given, all aliases are listed. Aliases may be nested and can contain anything that can be legally typed at the pdb prompt. Note! You *can* override internal pdb commands with aliases! Those internal commands are then hidden until the alias is removed. Aliasing is recursively applied to the first word of the command line; all other words in the line are left alone. As an example, here are two useful aliases (especially when placed in the .pdbrc file): # Print instance variables (usage "pi classInst") alias pi for k in %1.__dict__.keys(): print("%1.",k,"=",%1.__dict__[k]) # Print instance variables in self alias ps pi self """ args = arg.split() if len(args) == 0: keys = sorted(self.aliases.keys()) for alias in keys: self.message("%s = %s" % (alias, self.aliases[alias])) return if args[0] in self.aliases and len(args) == 1: self.message("%s = %s" % (args[0], self.aliases[args[0]])) else: self.aliases[args[0]] = ' '.join(args[1:]) def do_unalias(self, arg): """unalias name Delete the specified alias. """ args = arg.split() if len(args) == 0: return if args[0] in self.aliases: del self.aliases[args[0]] def complete_unalias(self, text, line, begidx, endidx): return [a for a in self.aliases if a.startswith(text)] # List of all the commands making the program resume execution. commands_resuming = ['do_continue', 'do_step', 'do_next', 'do_return', 'do_quit', 'do_jump'] # Print a traceback starting at the top stack frame. # The most recently entered frame is printed last; # this is different from dbx and gdb, but consistent with # the Python interpreter's stack trace. # It is also consistent with the up/down commands (which are # compatible with dbx and gdb: up moves towards 'main()' # and down moves towards the most recent stack frame). def print_stack_trace(self): try: for frame_lineno in self.stack: self.print_stack_entry(frame_lineno) except KeyboardInterrupt: pass def print_stack_entry(self, frame_lineno, prompt_prefix=line_prefix): frame, lineno = frame_lineno if frame is self.curframe: prefix = '> ' else: prefix = ' ' self.message(prefix + self.format_stack_entry(frame_lineno, prompt_prefix)) # Provide help def do_help(self, arg): """h(elp) Without argument, print the list of available commands. With a command name as argument, print help about that command. "help pdb" shows the full pdb documentation. "help exec" gives help on the ! command. """ if not arg: return cmd.Cmd.do_help(self, arg) try: try: topic = getattr(self, 'help_' + arg) return topic() except AttributeError: command = getattr(self, 'do_' + arg) except AttributeError: self.error('No help for %r' % arg) else: if sys.flags.optimize >= 2: self.error('No help for %r; please do not run Python with -OO ' 'if you need command help' % arg) return self.message(command.__doc__.rstrip()) do_h = do_help def help_exec(self): """(!) statement Execute the (one-line) statement in the context of the current stack frame. The exclamation point can be omitted unless the first word of the statement resembles a debugger command. To assign to a global variable you must always prefix the command with a 'global' command, e.g.: (Pdb) global list_options; list_options = ['-l'] (Pdb) """ self.message((self.help_exec.__doc__ or '').strip()) def help_pdb(self): help() # other helper functions def lookupmodule(self, filename): """Helper function for break/clear parsing -- may be overridden. lookupmodule() translates (possibly incomplete) file or module name into an absolute file name. """ if os.path.isabs(filename) and os.path.exists(filename): return filename f = os.path.join(sys.path[0], filename) if os.path.exists(f) and self.canonic(f) == self.mainpyfile: return f root, ext = os.path.splitext(filename) if ext == '': filename = filename + '.py' if os.path.isabs(filename): return filename for dirname in sys.path: while os.path.islink(dirname): dirname = os.readlink(dirname) fullname = os.path.join(dirname, filename) if os.path.exists(fullname): return fullname return None def _runscript(self, filename): # The script has to run in __main__ namespace (or imports from # __main__ will break). # # So we clear up the __main__ and set several special variables # (this gets rid of pdb's globals and cleans old variables on restarts). import __main__ __main__.__dict__.clear() __main__.__dict__.update({"__name__" : "__main__", "__file__" : filename, "__builtins__": __builtins__, }) # When bdb sets tracing, a number of call and line events happens # BEFORE debugger even reaches user's code (and the exact sequence of # events depends on python version). So we take special measures to # avoid stopping before we reach the main script (see user_line and # user_call for details). self._wait_for_mainpyfile = True self.mainpyfile = self.canonic(filename) self._user_requested_quit = False with open(filename, "rb") as fp: statement = "exec(compile(%r, %r, 'exec'))" % \ (, self.mainpyfile)
# Collect all command help into docstring, if not run with -OO if __doc__ is not None: # unfortunately we can't guess this order from the class definition _help_order = [ 'help', 'where', 'down', 'up', 'break', 'tbreak', 'clear', 'disable', 'enable', 'ignore', 'condition', 'commands', 'step', 'next', 'until', 'jump', 'return', 'retval', 'run', 'continue', 'list', 'longlist', 'args', 'p', 'pp', 'whatis', 'source', 'display', 'undisplay', 'interact', 'alias', 'unalias', 'debug', 'quit', ] for _command in _help_order: __doc__ += getattr(Pdb, 'do_' + _command).__doc__.strip() + '\n\n' __doc__ += Pdb.help_exec.__doc__ del _help_order, _command # Simplified interface
[docs]def run(statement, globals=None, locals=None): Pdb().run(statement, globals, locals)
[docs]def runeval(expression, globals=None, locals=None): return Pdb().runeval(expression, globals, locals)
def runctx(statement, globals, locals): # B/W compatibility run(statement, globals, locals)
[docs]def runcall(*args, **kwds): return Pdb().runcall(*args, **kwds)
[docs]def set_trace(): Pdb().set_trace(sys._getframe().f_back)
# Post-Mortem interface
[docs]def post_mortem(t=None): # handling the default if t is None: # sys.exc_info() returns (type, value, traceback) if an exception is # being handled, otherwise it returns None t = sys.exc_info()[2] if t is None: raise ValueError("A valid traceback must be passed if no " "exception is being handled") p = Pdb() p.reset() p.interaction(None, t)
[docs]def pm(): post_mortem(sys.last_traceback)
# Main program for testing TESTCMD = 'import x; x.main()' def test(): run(TESTCMD) # print help def help(): import pydoc pydoc.pager(__doc__) _usage = """\ usage: [-c command] ... pyfile [arg] ... Debug the Python program given by pyfile. Initial commands are read from .pdbrc files in your home directory and in the current directory, if they exist. Commands supplied with -c are executed after commands from .pdbrc files. To let the script run until an exception occurs, use "-c continue". To let the script run up to a given line X in the debugged file, use "-c 'until X'".""" def main(): import getopt opts, args = getopt.getopt(sys.argv[1:], 'hc:', ['--help', '--command=']) if not args: print(_usage) sys.exit(2) commands = [] for opt, optarg in opts: if opt in ['-h', '--help']: print(_usage) sys.exit() elif opt in ['-c', '--command']: commands.append(optarg) mainpyfile = args[0] # Get script filename if not os.path.exists(mainpyfile): print('Error:', mainpyfile, 'does not exist') sys.exit(1) sys.argv[:] = args # Hide "" and pdb options from argument list # Replace pdb's dir with script's dir in front of module search path. sys.path[0] = os.path.dirname(mainpyfile) # Note on saving/restoring sys.argv: it's a good idea when sys.argv was # modified by the script being debugged. It's a bad idea when it was # changed by the user from the command line. There is a "restart" command # which allows explicit specification of command line arguments. pdb = Pdb() pdb.rcLines.extend(commands) while True: try: pdb._runscript(mainpyfile) if pdb._user_requested_quit: break print("The program finished and will be restarted") except Restart: print("Restarting", mainpyfile, "with arguments:") print("\t" + " ".join(args)) except SystemExit: # In most cases SystemExit does not warrant a post-mortem session. print("The program exited via sys.exit(). Exit status:", end=' ') print(sys.exc_info()[1]) except SyntaxError: traceback.print_exc() sys.exit(1) except: traceback.print_exc() print("Uncaught exception. Entering post mortem debugging") print("Running 'cont' or 'step' will restart the program") t = sys.exc_info()[2] pdb.interaction(None, t) print("Post mortem debugger finished. The " + mainpyfile + " will be restarted") # When invoked as main program, invoke the debugger on a script if __name__ == '__main__': import pdb pdb.main()