Lib/bdb.py

   1 """Debugger basics"""
   2
   3 import sys
   4 import os
   5 import types
   6
   7 BdbQuit = 'bdb.BdbQuit' # Exception to give up completely
   8
   9
  10 class Bdb:
  11
  12     """Generic Python debugger base class.
  13
  14     This class takes care of details of the trace facility;
  15     a derived class should implement user interaction.
  16     The standard debugger class (pdb.Pdb) is an example.
  17     """
  18
  19     def __init__(self):
  20         self.breaks = {}
  21         self.fncache = {}
  22
  23     def canonic(self, filename):
  24         canonic = self.fncache.get(filename)
  25         if not canonic:
  26             canonic = os.path.abspath(filename)
  27             self.fncache[filename] = canonic
  28         return canonic
  29
  30     def reset(self):
  31         import linecache
  32         linecache.checkcache()
  33         self.botframe = None
  34         self.stopframe = None
  35         self.returnframe = None
  36         self.quitting = 0
  37
  38     def trace_dispatch(self, frame, event, arg):
  39         if self.quitting:
  40             return # None
  41         if event == 'line':
  42             return self.dispatch_line(frame)
  43         if event == 'call':
  44             return self.dispatch_call(frame, arg)
  45         if event == 'return':
  46             return self.dispatch_return(frame, arg)
  47         if event == 'exception':
  48             return self.dispatch_exception(frame, arg)
  49         print 'bdb.Bdb.dispatch: unknown debugging event:', `event`
  50         return self.trace_dispatch
  51
  52     def dispatch_line(self, frame):
  53         if self.stop_here(frame) or self.break_here(frame):
  54             self.user_line(frame)
  55             if self.quitting: raise BdbQuit
  56         return self.trace_dispatch
  57
  58     def dispatch_call(self, frame, arg):
  59         # XXX 'arg' is no longer used
  60         if self.botframe is None:
  61             # First call of dispatch since reset()
  62             self.botframe = frame
  63             return self.trace_dispatch
  64         if not (self.stop_here(frame) or self.break_anywhere(frame)):
  65             # No need to trace this function
  66             return # None
  67         self.user_call(frame, arg)
  68         if self.quitting: raise BdbQuit
  69         return self.trace_dispatch
  70
  71     def dispatch_return(self, frame, arg):
  72         if self.stop_here(frame) or frame == self.returnframe:
  73             self.user_return(frame, arg)
  74             if self.quitting: raise BdbQuit
  75
  76     def dispatch_exception(self, frame, arg):
  77         if self.stop_here(frame):
  78             self.user_exception(frame, arg)
  79             if self.quitting: raise BdbQuit
  80         return self.trace_dispatch
  81
  82     # Normally derived classes don't override the following
  83     # methods, but they may if they want to redefine the
  84     # definition of stopping and breakpoints.
  85
  86     def stop_here(self, frame):
  87         if self.stopframe is None:
  88             return 1
  89         if frame is self.stopframe:
  90             return 1
  91         while frame is not None and frame is not self.stopframe:
  92             if frame is self.botframe:
  93                 return 1
  94             frame = frame.f_back
  95         return 0
  96
  97     def break_here(self, frame):
  98         filename = self.canonic(frame.f_code.co_filename)
  99         if not self.breaks.has_key(filename):
 100             return 0
 101         lineno = frame.f_lineno
 102         if not lineno in self.breaks[filename]:
 103             return 0
 104         # flag says ok to delete temp. bp
 105         (bp, flag) = effective(filename, lineno, frame)
 106         if bp:
 107             self.currentbp = bp.number
 108             if (flag and bp.temporary):
 109                 self.do_clear(str(bp.number))
 110             return 1
 111         else:
 112             return 0
 113
 114     def break_anywhere(self, frame):
 115         return self.breaks.has_key(
 116             self.canonic(frame.f_code.co_filename))
 117
 118     # Derived classes should override the user_* methods
 119     # to gain control.
 120
 121     def user_call(self, frame, argument_list):
 122         """This method is called when there is the remote possibility
 123         that we ever need to stop in this function."""
 124         pass
 125
 126     def user_line(self, frame):
 127         """This method is called when we stop or break at this line."""
 128         pass
 129
 130     def user_return(self, frame, return_value):
 131         """This method is called when a return trap is set here."""
 132         pass
 133
 134     def user_exception(self, frame, (exc_type, exc_value, exc_traceback)):
 135         """This method is called if an exception occurs,
 136         but only if we are to stop at or just below this level."""
 137         pass
 138
 139     # Derived classes and clients can call the following methods
 140     # to affect the stepping state.
 141
 142     def set_step(self):
 143         """Stop after one line of code."""
 144         self.stopframe = None
 145         self.returnframe = None
 146         self.quitting = 0
 147
 148     def set_next(self, frame):
 149         """Stop on the next line in or below the given frame."""
 150         self.stopframe = frame
 151         self.returnframe = None
 152         self.quitting = 0
 153
 154     def set_return(self, frame):
 155         """Stop when returning from the given frame."""
 156         self.stopframe = frame.f_back
 157         self.returnframe = frame
 158         self.quitting = 0
 159
 160     def set_trace(self):
 161         """Start debugging from here."""
 162         try:
 163             1 + ''
 164         except:
 165             frame = sys.exc_info()[2].tb_frame.f_back
 166         self.reset()
 167         while frame:
 168             frame.f_trace = self.trace_dispatch
 169             self.botframe = frame
 170             frame = frame.f_back
 171         self.set_step()
 172         sys.settrace(self.trace_dispatch)
 173
 174     def set_continue(self):
 175         # Don't stop except at breakpoints or when finished
 176         self.stopframe = self.botframe
 177         self.returnframe = None
 178         self.quitting = 0
 179         if not self.breaks:
 180             # no breakpoints; run without debugger overhead
 181             sys.settrace(None)
 182             try:
 183                 1 + ''  # raise an exception
 184             except:
 185                 frame = sys.exc_info()[2].tb_frame.f_back
 186             while frame and frame is not self.botframe:
 187                 del frame.f_trace
 188                 frame = frame.f_back
 189
 190     def set_quit(self):
 191         self.stopframe = self.botframe
 192         self.returnframe = None
 193         self.quitting = 1
 194         sys.settrace(None)
 195
 196     # Derived classes and clients can call the following methods
 197     # to manipulate breakpoints.  These methods return an
 198     # error message is something went wrong, None if all is well.
 199     # Set_break prints out the breakpoint line and file:lineno.
 200     # Call self.get_*break*() to see the breakpoints or better
 201     # for bp in Breakpoint.bpbynumber: if bp: bp.bpprint().
 202
 203     def set_break(self, filename, lineno, temporary=0, cond = None):
 204         filename = self.canonic(filename)
 205         import linecache # Import as late as possible
 206         line = linecache.getline(filename, lineno)
 207         if not line:
 208             return 'Line %s:%d does not exist' % (filename,
 209                                    lineno)
 210         if not self.breaks.has_key(filename):
 211             self.breaks[filename] = []
 212         list = self.breaks[filename]
 213         if not lineno in list:
 214             list.append(lineno)
 215         bp = Breakpoint(filename, lineno, temporary, cond)
 216
 217     def clear_break(self, filename, lineno):
 218         filename = self.canonic(filename)
 219         if not self.breaks.has_key(filename):
 220             return 'There are no breakpoints in %s' % filename
 221         if lineno not in self.breaks[filename]:
 222             return 'There is no breakpoint at %s:%d' % (filename,
 223                                     lineno)
 224         # If there's only one bp in the list for that file,line
 225         # pair, then remove the breaks entry
 226         for bp in Breakpoint.bplist[filename, lineno][:]:
 227             bp.deleteMe()
 228         if not Breakpoint.bplist.has_key((filename, lineno)):
 229             self.breaks[filename].remove(lineno)
 230         if not self.breaks[filename]:
 231             del self.breaks[filename]
 232
 233     def clear_bpbynumber(self, arg):
 234         try:
 235             number = int(arg)
 236         except:
 237             return 'Non-numeric breakpoint number (%s)' % arg
 238         try:
 239             bp = Breakpoint.bpbynumber[number]
 240         except IndexError:
 241             return 'Breakpoint number (%d) out of range' % number
 242         if not bp:
 243             return 'Breakpoint (%d) already deleted' % number
 244         self.clear_break(bp.file, bp.line)
 245
 246     def clear_all_file_breaks(self, filename):
 247         filename = self.canonic(filename)
 248         if not self.breaks.has_key(filename):
 249             return 'There are no breakpoints in %s' % filename
 250         for line in self.breaks[filename]:
 251             blist = Breakpoint.bplist[filename, line]
 252             for bp in blist:
 253                 bp.deleteMe()
 254         del self.breaks[filename]
 255
 256     def clear_all_breaks(self):
 257         if not self.breaks:
 258             return 'There are no breakpoints'
 259         for bp in Breakpoint.bpbynumber:
 260             if bp:
 261                 bp.deleteMe()
 262         self.breaks = {}
 263
 264     def get_break(self, filename, lineno):
 265         filename = self.canonic(filename)
 266         return self.breaks.has_key(filename) and \
 267             lineno in self.breaks[filename]
 268
 269     def get_breaks(self, filename, lineno):
 270         filename = self.canonic(filename)
 271         return self.breaks.has_key(filename) and \
 272             lineno in self.breaks[filename] and \
 273             Breakpoint.bplist[filename, lineno] or []
 274
 275     def get_file_breaks(self, filename):
 276         filename = self.canonic(filename)
 277         if self.breaks.has_key(filename):
 278             return self.breaks[filename]
 279         else:
 280             return []
 281
 282     def get_all_breaks(self):
 283         return self.breaks
 284
 285     # Derived classes and clients can call the following method
 286     # to get a data structure representing a stack trace.
 287
 288     def get_stack(self, f, t):
 289         stack = []
 290         if t and t.tb_frame is f:
 291             t = t.tb_next
 292         while f is not None:
 293             stack.append((f, f.f_lineno))
 294             if f is self.botframe:
 295                 break
 296             f = f.f_back
 297         stack.reverse()
 298         i = max(0, len(stack) - 1)
 299         while t is not None:
 300             stack.append((t.tb_frame, t.tb_lineno))
 301             t = t.tb_next
 302         return stack, i
 303
 304     #
 305
 306     def format_stack_entry(self, frame_lineno, lprefix=': '):
 307         import linecache, repr, string
 308         frame, lineno = frame_lineno
 309         filename = self.canonic(frame.f_code.co_filename)
 310         s = filename + '(' + `lineno` + ')'
 311         if frame.f_code.co_name:
 312             s = s + frame.f_code.co_name
 313         else:
 314             s = s + "<lambda>"
 315         if frame.f_locals.has_key('__args__'):
 316             args = frame.f_locals['__args__']
 317         else:
 318             args = None
 319         if args:
 320             s = s + repr.repr(args)
 321         else:
 322             s = s + '()'
 323         if frame.f_locals.has_key('__return__'):
 324             rv = frame.f_locals['__return__']
 325             s = s + '->'
 326             s = s + repr.repr(rv)
 327         line = linecache.getline(filename, lineno)
 328         if line: s = s + lprefix + string.strip(line)
 329         return s
 330
 331     # The following two methods can be called by clients to use
 332     # a debugger to debug a statement, given as a string.
 333
 334     def run(self, cmd, globals=None, locals=None):
 335         if globals is None:
 336             import __main__
 337             globals = __main__.__dict__
 338         if locals is None:
 339             locals = globals
 340         self.reset()
 341         sys.settrace(self.trace_dispatch)
 342         if not isinstance(cmd, types.CodeType):
 343             cmd = cmd+'\n'
 344         try:
 345             try:
 346                 exec cmd in globals, locals
 347             except BdbQuit:
 348                 pass
 349         finally:
 350             self.quitting = 1
 351             sys.settrace(None)
 352
 353     def runeval(self, expr, globals=None, locals=None):
 354         if globals is None:
 355             import __main__
 356             globals = __main__.__dict__
 357         if locals is None:
 358             locals = globals
 359         self.reset()
 360         sys.settrace(self.trace_dispatch)
 361         if not isinstance(expr, types.CodeType):
 362             expr = expr+'\n'
 363         try:
 364             try:
 365                 return eval(expr, globals, locals)
 366             except BdbQuit:
 367                 pass
 368         finally:
 369             self.quitting = 1
 370             sys.settrace(None)
 371
 372     def runctx(self, cmd, globals, locals):
 373         # B/W compatibility
 374         self.run(cmd, globals, locals)
 375
 376     # This method is more useful to debug a single function call.
 377
 378     def runcall(self, func, *args):
 379         self.reset()
 380         sys.settrace(self.trace_dispatch)
 381         res = None
 382         try:
 383             try:
 384                 res = apply(func, args)
 385             except BdbQuit:
 386                 pass
 387         finally:
 388             self.quitting = 1
 389             sys.settrace(None)
 390         return res
 391
 392
 393 def set_trace():
 394     Bdb().set_trace()
 395
 396
 397 class Breakpoint:
 398
 399     """Breakpoint class
 400
 401     Implements temporary breakpoints, ignore counts, disabling and
 402     (re)-enabling, and conditionals.
 403
 404     Breakpoints are indexed by number through bpbynumber and by
 405     the file,line tuple using bplist.  The former points to a
 406     single instance of class Breakpoint.  The latter points to a
 407     list of such instances since there may be more than one
 408     breakpoint per line.
 409
 410     """
 411
 412     # XXX Keeping state in the class is a mistake -- this means
 413     # you cannot have more than one active Bdb instance.
 414
 415     next = 1        # Next bp to be assigned
 416     bplist = {}     # indexed by (file, lineno) tuple
 417     bpbynumber = [None] # Each entry is None or an instance of Bpt
 418                 # index 0 is unused, except for marking an
 419                 # effective break .... see effective()
 420
 421     def __init__(self, file, line, temporary=0, cond = None):
 422         self.file = file    # This better be in canonical form!
 423         self.line = line
 424         self.temporary = temporary
 425         self.cond = cond
 426         self.enabled = 1
 427         self.ignore = 0
 428         self.hits = 0
 429         self.number = Breakpoint.next
 430         Breakpoint.next = Breakpoint.next + 1
 431         # Build the two lists
 432         self.bpbynumber.append(self)
 433         if self.bplist.has_key((file, line)):
 434             self.bplist[file, line].append(self)
 435         else:
 436             self.bplist[file, line] = [self]
 437
 438
 439     def deleteMe(self):
 440         index = (self.file, self.line)
 441         self.bpbynumber[self.number] = None   # No longer in list
 442         self.bplist[index].remove(self)
 443         if not self.bplist[index]:
 444             # No more bp for this f:l combo
 445             del self.bplist[index]
 446
 447     def enable(self):
 448         self.enabled = 1
 449
 450     def disable(self):
 451         self.enabled = 0
 452
 453     def bpprint(self):
 454         if self.temporary:
 455            disp = 'del  '
 456         else:
 457            disp = 'keep '
 458         if self.enabled:
 459            disp = disp + 'yes'
 460         else:
 461            disp = disp + 'no '
 462         print '%-4dbreakpoint    %s at %s:%d' % (self.number, disp,
 463                              self.file, self.line)
 464         if self.cond:
 465             print '\tstop only if %s' % (self.cond,)
 466         if self.ignore:
 467             print '\tignore next %d hits' % (self.ignore)
 468         if (self.hits):
 469             if (self.hits > 1): ss = 's'
 470             else: ss = ''
 471             print ('\tbreakpoint already hit %d time%s' %
 472                    (self.hits, ss))
 473
 474 # -----------end of Breakpoint class----------
 475
 476 # Determines if there is an effective (active) breakpoint at this
 477 # line of code.  Returns breakpoint number or 0 if none
 478 def effective(file, line, frame):
 479     """Determine which breakpoint for this file:line is to be acted upon.
 480
 481     Called only if we know there is a bpt at this
 482     location.  Returns breakpoint that was triggered and a flag
 483     that indicates if it is ok to delete a temporary bp.
 484
 485     """
 486     possibles = Breakpoint.bplist[file,line]
 487     for i in range(0, len(possibles)):
 488         b = possibles[i]
 489         if b.enabled == 0:
 490             continue
 491         # Count every hit when bp is enabled
 492         b.hits = b.hits + 1
 493         if not b.cond:
 494             # If unconditional, and ignoring,
 495             # go on to next, else break
 496             if b.ignore > 0:
 497                 b.ignore = b.ignore -1
 498                 continue
 499             else:
 500                 # breakpoint and marker that's ok
 501                 # to delete if temporary
 502                 return (b,1)
 503         else:
 504             # Conditional bp.
 505             # Ignore count applies only to those bpt hits where the
 506             # condition evaluates to true.
 507             try:
 508                 val = eval(b.cond, frame.f_globals,
 509                        frame.f_locals)
 510                 if val:
 511                     if b.ignore > 0:
 512                         b.ignore = b.ignore -1
 513                         # continue
 514                     else:
 515                         return (b,1)
 516                 # else:
 517                 #   continue
 518             except:
 519                 # if eval fails, most conservative
 520                 # thing is to stop on breakpoint
 521                 # regardless of ignore count.
 522                 # Don't delete temporary,
 523                 # as another hint to user.
 524                 return (b,0)
 525     return (None, None)
 526
 527 # -------------------- testing --------------------
 528
 529 class Tdb(Bdb):
 530     def user_call(self, frame, args):
 531         name = frame.f_code.co_name
 532         if not name: name = '???'
 533         print '+++ call', name, args
 534     def user_line(self, frame):
 535         import linecache, string
 536         name = frame.f_code.co_name
 537         if not name: name = '???'
 538         fn = self.canonic(frame.f_code.co_filename)
 539         line = linecache.getline(fn, frame.f_lineno)
 540         print '+++', fn, frame.f_lineno, name, ':', string.strip(line)
 541     def user_return(self, frame, retval):
 542         print '+++ return', retval
 543     def user_exception(self, frame, exc_stuff):
 544         print '+++ exception', exc_stuff
 545         self.set_continue()
 546
 547 def foo(n):
 548     print 'foo(', n, ')'
 549     x = bar(n*10)
 550     print 'bar returned', x
 551
 552 def bar(a):
 553     print 'bar(', a, ')'
 554     return a/2
 555
 556 def test():
 557     t = Tdb()
 558     t.run('import bdb; bdb.foo(10)')