4 perl5db.pl - the perl debugger
8 perl -d your_Perl_script
12 C<perl5db.pl> is the perl debugger. It is loaded automatically by Perl when
13 you invoke a script with C<perl -d>. This documentation tries to outline the
14 structure and services provided by C<perl5db.pl>, and to describe how you
19 The debugger can look pretty forbidding to many Perl programmers. There are
20 a number of reasons for this, many stemming out of the debugger's history.
22 When the debugger was first written, Perl didn't have a lot of its nicer
23 features - no references, no lexical variables, no closures, no object-oriented
24 programming. So a lot of the things one would normally have done using such
25 features was done using global variables, globs and the C<local()> operator
28 Some of these have survived into the current debugger; a few of the more
29 interesting and still-useful idioms are noted in this section, along with notes
30 on the comments themselves.
32 =head2 Why not use more lexicals?
34 Experienced Perl programmers will note that the debugger code tends to use
35 mostly package globals rather than lexically-scoped variables. This is done
36 to allow a significant amount of control of the debugger from outside the
39 Unfortunately, though the variables are accessible, they're not well
40 documented, so it's generally been a decision that hasn't made a lot of
41 difference to most users. Where appropriate, comments have been added to
42 make variables more accessible and usable, with the understanding that these
43 I<are> debugger internals, and are therefore subject to change. Future
44 development should probably attempt to replace the globals with a well-defined
45 API, but for now, the variables are what we've got.
47 =head2 Automated variable stacking via C<local()>
49 As you may recall from reading C<perlfunc>, the C<local()> operator makes a
50 temporary copy of a variable in the current scope. When the scope ends, the
51 old copy is restored. This is often used in the debugger to handle the
52 automatic stacking of variables during recursive calls:
57 # Do some stuff, then ...
61 What happens is that on entry to the subroutine, C<$some_global> is localized,
62 then altered. When the subroutine returns, Perl automatically undoes the
63 localization, restoring the previous value. Voila, automatic stack management.
65 The debugger uses this trick a I<lot>. Of particular note is C<DB::eval>,
66 which lets the debugger get control inside of C<eval>'ed code. The debugger
67 localizes a saved copy of C<$@> inside the subroutine, which allows it to
68 keep C<$@> safe until it C<DB::eval> returns, at which point the previous
69 value of C<$@> is restored. This makes it simple (well, I<simpler>) to keep
70 track of C<$@> inside C<eval>s which C<eval> other C<eval's>.
72 In any case, watch for this pattern. It occurs fairly often.
76 This is used to cleverly reverse the sense of a logical test depending on
77 the value of an auxiliary variable. For instance, the debugger's C<S>
78 (search for subroutines by pattern) allows you to negate the pattern
81 # Find all non-'foo' subs:
84 Boolean algebra states that the truth table for XOR looks like this:
90 (! not present and no match) --> false, don't print
94 (! not present and matches) --> true, print
98 (! present and no match) --> true, print
102 (! present and matches) --> false, don't print
106 As you can see, the first pair applies when C<!> isn't supplied, and
107 the second pair applies when it is. The XOR simply allows us to
108 compact a more complicated if-then-elseif-else into a more elegant
109 (but perhaps overly clever) single test. After all, it needed this
112 =head2 FLAGS, FLAGS, FLAGS
114 There is a certain C programming legacy in the debugger. Some variables,
115 such as C<$single>, C<$trace>, and C<$frame>, have I<magical> values composed
116 of 1, 2, 4, etc. (powers of 2) OR'ed together. This allows several pieces
117 of state to be stored independently in a single scalar.
123 is checking to see if the appropriate bit is on. Since each bit can be
124 "addressed" independently in this way, C<$scalar> is acting sort of like
125 an array of bits. Obviously, since the contents of C<$scalar> are just a
126 bit-pattern, we can save and restore it easily (it will just look like
129 The problem, is of course, that this tends to leave magic numbers scattered
130 all over your program whenever a bit is set, cleared, or checked. So why do
137 First, doing an arithmetical or bitwise operation on a scalar is
138 just about the fastest thing you can do in Perl: C<use constant> actually
139 creates a subroutine call, and array and hash lookups are much slower. Is
140 this over-optimization at the expense of readability? Possibly, but the
141 debugger accesses these variables a I<lot>. Any rewrite of the code will
142 probably have to benchmark alternate implementations and see which is the
143 best balance of readability and speed, and then document how it actually
148 Second, it's very easy to serialize a scalar number. This is done in
149 the restart code; the debugger state variables are saved in C<%ENV> and then
150 restored when the debugger is restarted. Having them be just numbers makes
155 Third, some of these variables are being shared with the Perl core
156 smack in the middle of the interpreter's execution loop. It's much faster for
157 a C program (like the interpreter) to check a bit in a scalar than to access
158 several different variables (or a Perl array).
162 =head2 What are those C<XXX> comments for?
164 Any comment containing C<XXX> means that the comment is either somewhat
165 speculative - it's not exactly clear what a given variable or chunk of
166 code is doing, or that it is incomplete - the basics may be clear, but the
167 subtleties are not completely documented.
169 Send in a patch if you can clear up, fill out, or clarify an C<XXX>.
171 =head1 DATA STRUCTURES MAINTAINED BY CORE
173 There are a number of special data structures provided to the debugger by
174 the Perl interpreter.
176 The array C<@{$main::{'_<'.$filename}}> (aliased locally to C<@dbline> via glob
177 assignment) contains the text from C<$filename>, with each element
178 corresponding to a single line of C<$filename>.
180 The hash C<%{'_<'.$filename}> (aliased locally to C<%dbline> via glob
181 assignment) contains breakpoints and actions. The keys are line numbers;
182 you can set individual values, but not the whole hash. The Perl interpreter
183 uses this hash to determine where breakpoints have been set. Any true value is
184 considered to be a breakpoint; C<perl5db.pl> uses C<$break_condition\0$action>.
185 Values are magical in numeric context: 1 if the line is breakable, 0 if not.
187 The scalar C<${"_<$filename"}> simply contains the string C<_<$filename>.
188 This is also the case for evaluated strings that contain subroutines, or
189 which are currently being executed. The $filename for C<eval>ed strings looks
190 like C<(eval 34)> or C<(re_eval 19)>.
192 =head1 DEBUGGER STARTUP
194 When C<perl5db.pl> starts, it reads an rcfile (C<perl5db.ini> for
195 non-interactive sessions, C<.perldb> for interactive ones) that can set a number
196 of options. In addition, this file may define a subroutine C<&afterinit>
197 that will be executed (in the debugger's context) after the debugger has
200 Next, it checks the C<PERLDB_OPTS> environment variable and treats its
201 contents as the argument of a C<o> command in the debugger.
203 =head2 STARTUP-ONLY OPTIONS
205 The following options can only be specified at startup.
206 To set them in your rcfile, add a call to
207 C<&parse_options("optionName=new_value")>.
213 the TTY to use for debugging i/o.
217 if set, goes in NonStop mode. On interrupt, if TTY is not set,
218 uses the value of noTTY or F<$HOME/.perldbtty$$> to find TTY using
219 Term::Rendezvous. Current variant is to have the name of TTY in this
224 if false, a dummy ReadLine is used, so you can debug
225 ReadLine applications.
229 if true, no i/o is performed until interrupt.
233 file or pipe to print line number info to. If it is a
234 pipe, a short "emacs like" message is used.
238 host:port to connect to on remote host for remote debugging.
242 file to store session history to. There is no default and so no
243 history file is written unless this variable is explicitly set.
247 number of commands to store to the file specified in C<HistFile>.
254 &parse_options("NonStop=1 LineInfo=db.out");
255 sub afterinit { $trace = 1; }
257 The script will run without human intervention, putting trace
258 information into C<db.out>. (If you interrupt it, you had better
259 reset C<LineInfo> to something I<interactive>!)
261 =head1 INTERNALS DESCRIPTION
263 =head2 DEBUGGER INTERFACE VARIABLES
265 Perl supplies the values for C<%sub>. It effectively inserts
266 a C<&DB::DB();> in front of each place that can have a
267 breakpoint. At each subroutine call, it calls C<&DB::sub> with
268 C<$DB::sub> set to the called subroutine. It also inserts a C<BEGIN
269 {require 'perl5db.pl'}> before the first line.
271 After each C<require>d file is compiled, but before it is executed, a
272 call to C<&DB::postponed($main::{'_<'.$filename})> is done. C<$filename>
273 is the expanded name of the C<require>d file (as found via C<%INC>).
275 =head3 IMPORTANT INTERNAL VARIABLES
279 Used to control when the debugger will attempt to acquire another TTY to be
284 =item * 1 - on C<fork()>
286 =item * 2 - debugger is started inside debugger
288 =item * 4 - on startup
294 The value -2 indicates that no return value should be printed.
295 Any other positive value causes C<DB::sub> to print return values.
299 The item to be eval'ed by C<DB::eval>. Used to prevent messing with the current
300 contents of C<@_> when C<DB::eval> is called.
304 Determines what messages (if any) will get printed when a subroutine (or eval)
305 is entered or exited.
309 =item * 0 - No enter/exit messages
311 =item * 1 - Print I<entering> messages on subroutine entry
313 =item * 2 - Adds exit messages on subroutine exit. If no other flag is on, acts like 1+2.
315 =item * 4 - Extended messages: C<< <in|out> I<context>=I<fully-qualified sub name> from I<file>:I<line> >>. If no other flag is on, acts like 1+4.
317 =item * 8 - Adds parameter information to messages, and overloaded stringify and tied FETCH is enabled on the printed arguments. Ignored if C<4> is not on.
319 =item * 16 - Adds C<I<context> return from I<subname>: I<value>> messages on subroutine/eval exit. Ignored if C<4> is is not on.
323 To get everything, use C<$frame=30> (or C<o f=30> as a debugger command).
324 The debugger internally juggles the value of C<$frame> during execution to
325 protect external modules that the debugger uses from getting traced.
329 Tracks current debugger nesting level. Used to figure out how many
330 C<E<lt>E<gt>> pairs to surround the line number with when the debugger
331 outputs a prompt. Also used to help determine if the program has finished
332 during command parsing.
334 =head4 C<$onetimeDump>
336 Controls what (if anything) C<DB::eval()> will print after evaluating an
341 =item * C<undef> - don't print anything
343 =item * C<dump> - use C<dumpvar.pl> to display the value returned
345 =item * C<methods> - print the methods callable on the first item returned
349 =head4 C<$onetimeDumpDepth>
351 Controls how far down C<dumpvar.pl> will go before printing C<...> while
352 dumping a structure. Numeric. If C<undef>, print all levels.
356 Used to track whether or not an C<INT> signal has been detected. C<DB::DB()>,
357 which is called before every statement, checks this and puts the user into
358 command mode if it finds C<$signal> set to a true value.
362 Controls behavior during single-stepping. Stacked in C<@stack> on entry to
363 each subroutine; popped again at the end of each subroutine.
367 =item * 0 - run continuously.
369 =item * 1 - single-step, go into subs. The C<s> command.
371 =item * 2 - single-step, don't go into subs. The C<n> command.
373 =item * 4 - print current sub depth (turned on to force this when C<too much
380 Controls the output of trace information.
384 =item * 1 - The C<t> command was entered to turn on tracing (every line executed is printed)
386 =item * 2 - watch expressions are active
388 =item * 4 - user defined a C<watchfunction()> in C<afterinit()>
392 =head4 C<$slave_editor>
394 1 if C<LINEINFO> was directed to a pipe; 0 otherwise.
398 Stack of filehandles that C<DB::readline()> will read commands from.
399 Manipulated by the debugger's C<source> command and C<DB::readline()> itself.
403 Local alias to the magical line array, C<@{$main::{'_<'.$filename}}> ,
404 supplied by the Perl interpreter to the debugger. Contains the source.
408 Previous values of watch expressions. First set when the expression is
409 entered; reset whenever the watch expression changes.
413 Saves important globals (C<$@>, C<$!>, C<$^E>, C<$,>, C<$/>, C<$\>, C<$^W>)
414 so that the debugger can substitute safe values while it's running, and
415 restore them when it returns control.
419 Saves the current value of C<$single> on entry to a subroutine.
420 Manipulated by the C<c> command to turn off tracing in all subs above the
425 The 'watch' expressions: to be evaluated before each line is executed.
429 The typeahead buffer, used by C<DB::readline>.
433 Command aliases. Stored as character strings to be substituted for a command
436 =head4 C<%break_on_load>
438 Keys are file names, values are 1 (break when this file is loaded) or undef
439 (don't break when it is loaded).
443 Keys are line numbers, values are C<condition\0action>. If used in numeric
444 context, values are 0 if not breakable, 1 if breakable, no matter what is
445 in the actual hash entry.
447 =head4 C<%had_breakpoints>
449 Keys are file names; values are bitfields:
453 =item * 1 - file has a breakpoint in it.
455 =item * 2 - file has an action in it.
459 A zero or undefined value means this file has neither.
463 Stores the debugger options. These are character string values.
467 Saves breakpoints for code that hasn't been compiled yet.
468 Keys are subroutine names, values are:
472 =item * C<compile> - break when this sub is compiled
474 =item * C<< break +0 if <condition> >> - break (conditionally) at the start of this routine. The condition will be '1' if no condition was specified.
478 =head4 C<%postponed_file>
480 This hash keeps track of breakpoints that need to be set for files that have
481 not yet been compiled. Keys are filenames; values are references to hashes.
482 Each of these hashes is keyed by line number, and its values are breakpoint
483 definitions (C<condition\0action>).
485 =head1 DEBUGGER INITIALIZATION
487 The debugger's initialization actually jumps all over the place inside this
488 package. This is because there are several BEGIN blocks (which of course
489 execute immediately) spread through the code. Why is that?
491 The debugger needs to be able to change some things and set some things up
492 before the debugger code is compiled; most notably, the C<$deep> variable that
493 C<DB::sub> uses to tell when a program has recursed deeply. In addition, the
494 debugger has to turn off warnings while the debugger code is compiled, but then
495 restore them to their original setting before the program being debugged begins
498 The first C<BEGIN> block simply turns off warnings by saving the current
499 setting of C<$^W> and then setting it to zero. The second one initializes
500 the debugger variables that are needed before the debugger begins executing.
501 The third one puts C<$^X> back to its former value.
503 We'll detail the second C<BEGIN> block later; just remember that if you need
504 to initialize something before the debugger starts really executing, that's
511 BEGIN {eval 'use IO::Handle'}; # Needed for flush only? breaks under miniperl
513 # Debugger for Perl 5.00x; perl5db.pl patch level:
516 $header = "perl5db.pl version $VERSION";
518 =head1 DEBUGGER ROUTINES
522 This function replaces straight C<eval()> inside the debugger; it simplifies
523 the process of evaluating code in the user's context.
525 The code to be evaluated is passed via the package global variable
526 C<$DB::evalarg>; this is done to avoid fiddling with the contents of C<@_>.
528 Before we do the C<eval()>, we preserve the current settings of C<$trace>,
529 C<$single>, C<$^D> and C<$usercontext>. The latter contains the
530 preserved values of C<$@>, C<$!>, C<$^E>, C<$,>, C<$/>, C<$\>, C<$^W> and the
531 user's current package, grabbed when C<DB::DB> got control. This causes the
532 proper context to be used when the eval is actually done. Afterward, we
533 restore C<$trace>, C<$single>, and C<$^D>.
535 Next we need to handle C<$@> without getting confused. We save C<$@> in a
536 local lexical, localize C<$saved[0]> (which is where C<save()> will put
537 C<$@>), and then call C<save()> to capture C<$@>, C<$!>, C<$^E>, C<$,>,
538 C<$/>, C<$\>, and C<$^W>) and set C<$,>, C<$/>, C<$\>, and C<$^W> to values
539 considered sane by the debugger. If there was an C<eval()> error, we print
540 it on the debugger's output. If C<$onetimedump> is defined, we call
541 C<dumpit> if it's set to 'dump', or C<methods> if it's set to
542 'methods'. Setting it to something else causes the debugger to do the eval
543 but not print the result - handy if you want to do something else with it
544 (the "watch expressions" code does this to get the value of the watch
545 expression but not show it unless it matters).
547 In any case, we then return the list of output from C<eval> to the caller,
548 and unwinding restores the former version of C<$@> in C<@saved> as well
549 (the localization of C<$saved[0]> goes away at the end of this scope).
551 =head3 Parameters and variables influencing execution of DB::eval()
553 C<DB::eval> isn't parameterized in the standard way; this is to keep the
554 debugger's calls to C<DB::eval()> from mucking with C<@_>, among other things.
555 The variables listed below influence C<DB::eval()>'s execution directly.
559 =item C<$evalarg> - the thing to actually be eval'ed
561 =item C<$trace> - Current state of execution tracing
563 =item C<$single> - Current state of single-stepping
565 =item C<$onetimeDump> - what is to be displayed after the evaluation
567 =item C<$onetimeDumpDepth> - how deep C<dumpit()> should go when dumping results
571 The following variables are altered by C<DB::eval()> during its execution. They
572 are "stacked" via C<local()>, enabling recursive calls to C<DB::eval()>.
576 =item C<@res> - used to capture output from actual C<eval>.
578 =item C<$otrace> - saved value of C<$trace>.
580 =item C<$osingle> - saved value of C<$single>.
582 =item C<$od> - saved value of C<$^D>.
584 =item C<$saved[0]> - saved value of C<$@>.
586 =item $\ - for output of C<$@> if there is an evaluation error.
590 =head3 The problem of lexicals
592 The context of C<DB::eval()> presents us with some problems. Obviously,
593 we want to be 'sandboxed' away from the debugger's internals when we do
594 the eval, but we need some way to control how punctuation variables and
595 debugger globals are used.
597 We can't use local, because the code inside C<DB::eval> can see localized
598 variables; and we can't use C<my> either for the same reason. The code
599 in this routine compromises and uses C<my>.
601 After this routine is over, we don't have user code executing in the debugger's
602 context, so we can use C<my> freely.
606 ############################################## Begin lexical danger zone
608 # 'my' variables used here could leak into (that is, be visible in)
609 # the context that the code being evaluated is executing in. This means that
610 # the code could modify the debugger's variables.
612 # Fiddling with the debugger's context could be Bad. We insulate things as
617 # 'my' would make it visible from user code
618 # but so does local! --tchrist
619 # Remember: this localizes @DB::res, not @main::res.
623 # Try to keep the user code from messing with us. Save these so that
624 # even if the eval'ed code changes them, we can put them back again.
625 # Needed because the user could refer directly to the debugger's
626 # package globals (and any 'my' variables in this containing scope)
627 # inside the eval(), and we want to try to stay safe.
628 local $otrace = $trace;
629 local $osingle = $single;
632 # Untaint the incoming eval() argument.
633 { ($evalarg) = $evalarg =~ /(.*)/s; }
635 # $usercontext built in DB::DB near the comment
636 # "set up the context for DB::eval ..."
637 # Evaluate and save any results.
638 @res = eval "$usercontext $evalarg;\n"; # '\n' for nice recursive debug
640 # Restore those old values.
646 # Save the current value of $@, and preserve it in the debugger's copy
647 # of the saved precious globals.
650 # Since we're only saving $@, we only have to localize the array element
651 # that it will be stored in.
652 local $saved[0]; # Preserve the old value of $@
655 # Now see whether we need to report an error back to the user.
661 # Display as required by the caller. $onetimeDump and $onetimedumpDepth
662 # are package globals.
663 elsif ($onetimeDump) {
664 if ( $onetimeDump eq 'dump' ) {
665 local $option{dumpDepth} = $onetimedumpDepth
666 if defined $onetimedumpDepth;
667 dumpit( $OUT, \@res );
669 elsif ( $onetimeDump eq 'methods' ) {
672 } ## end elsif ($onetimeDump)
676 ############################################## End lexical danger zone
678 # After this point it is safe to introduce lexicals.
679 # The code being debugged will be executing in its own context, and
680 # can't see the inside of the debugger.
682 # However, one should not overdo it: leave as much control from outside as
683 # possible. If you make something a lexical, it's not going to be addressable
684 # from outside the debugger even if you know its name.
686 # This file is automatically included if you do perl -d.
687 # It's probably not useful to include this yourself.
689 # Before venturing further into these twisty passages, it is
690 # wise to read the perldebguts man page or risk the ire of dragons.
692 # (It should be noted that perldebguts will tell you a lot about
693 # the underlying mechanics of how the debugger interfaces into the
694 # Perl interpreter, but not a lot about the debugger itself. The new
695 # comments in this code try to address this problem.)
697 # Note that no subroutine call is possible until &DB::sub is defined
698 # (for subroutines defined outside of the package DB). In fact the same is
699 # true if $deep is not defined.
701 # Enhanced by ilya@math.ohio-state.edu (Ilya Zakharevich)
703 # modified Perl debugger, to be run from Emacs in perldb-mode
704 # Ray Lischner (uunet!mntgfx!lisch) as of 5 Nov 1990
705 # Johan Vromans -- upgrade to 4.0 pl 10
706 # Ilya Zakharevich -- patches after 5.001 (and some before ;-)
708 # (We have made efforts to clarify the comments in the change log
709 # in other places; some of them may seem somewhat obscure as they
710 # were originally written, and explaining them away from the code
711 # in question seems conterproductive.. -JM)
713 ########################################################################
715 # + A lot of things changed after 0.94. First of all, core now informs
716 # debugger about entry into XSUBs, overloaded operators, tied operations,
717 # BEGIN and END. Handy with `O f=2'.
718 # + This can make debugger a little bit too verbose, please be patient
719 # and report your problems promptly.
720 # + Now the option frame has 3 values: 0,1,2. XXX Document!
721 # + Note that if DESTROY returns a reference to the object (or object),
722 # the deletion of data may be postponed until the next function call,
723 # due to the need to examine the return value.
726 # + `v' command shows versions.
729 # + `v' command shows version of readline.
730 # primitive completion works (dynamic variables, subs for `b' and `l',
731 # options). Can `p %var'
732 # + Better help (`h <' now works). New commands <<, >>, {, {{.
733 # {dump|print}_trace() coded (to be able to do it from <<cmd).
734 # + `c sub' documented.
735 # + At last enough magic combined to stop after the end of debuggee.
736 # + !! should work now (thanks to Emacs bracket matching an extra
737 # `]' in a regexp is caught).
738 # + `L', `D' and `A' span files now (as documented).
739 # + Breakpoints in `require'd code are possible (used in `R').
740 # + Some additional words on internal work of debugger.
741 # + `b load filename' implemented.
742 # + `b postpone subr' implemented.
743 # + now only `q' exits debugger (overwritable on $inhibit_exit).
744 # + When restarting debugger breakpoints/actions persist.
745 # + Buglet: When restarting debugger only one breakpoint/action per
746 # autoloaded function persists.
748 # Changes: 0.97: NonStop will not stop in at_exit().
749 # + Option AutoTrace implemented.
750 # + Trace printed differently if frames are printed too.
751 # + new `inhibitExit' option.
752 # + printing of a very long statement interruptible.
753 # Changes: 0.98: New command `m' for printing possible methods
754 # + 'l -' is a synonym for `-'.
755 # + Cosmetic bugs in printing stack trace.
756 # + `frame' & 8 to print "expanded args" in stack trace.
757 # + Can list/break in imported subs.
758 # + new `maxTraceLen' option.
759 # + frame & 4 and frame & 8 granted.
761 # + nonstoppable lines do not have `:' near the line number.
762 # + `b compile subname' implemented.
763 # + Will not use $` any more.
764 # + `-' behaves sane now.
765 # Changes: 0.99: Completion for `f', `m'.
766 # + `m' will remove duplicate names instead of duplicate functions.
767 # + `b load' strips trailing whitespace.
768 # completion ignores leading `|'; takes into account current package
769 # when completing a subroutine name (same for `l').
770 # Changes: 1.07: Many fixed by tchrist 13-March-2000
772 # + Added bare minimal security checks on perldb rc files, plus
773 # comments on what else is needed.
774 # + Fixed the ornaments that made "|h" completely unusable.
775 # They are not used in print_help if they will hurt. Strip pod
776 # if we're paging to less.
777 # + Fixed mis-formatting of help messages caused by ornaments
778 # to restore Larry's original formatting.
779 # + Fixed many other formatting errors. The code is still suboptimal,
780 # and needs a lot of work at restructuring. It's also misindented
782 # + Fixed bug where trying to look at an option like your pager
784 # + Fixed some $? processing. Note: if you use csh or tcsh, you will
785 # lose. You should consider shell escapes not using their shell,
786 # or else not caring about detailed status. This should really be
787 # unified into one place, too.
788 # + Fixed bug where invisible trailing whitespace on commands hoses you,
789 # tricking Perl into thinking you weren't calling a debugger command!
790 # + Fixed bug where leading whitespace on commands hoses you. (One
791 # suggests a leading semicolon or any other irrelevant non-whitespace
792 # to indicate literal Perl code.)
793 # + Fixed bugs that ate warnings due to wrong selected handle.
794 # + Fixed a precedence bug on signal stuff.
795 # + Fixed some unseemly wording.
796 # + Fixed bug in help command trying to call perl method code.
797 # + Fixed to call dumpvar from exception handler. SIGPIPE killed us.
799 # + Added some comments. This code is still nasty spaghetti.
800 # + Added message if you clear your pre/post command stacks which was
801 # very easy to do if you just typed a bare >, <, or {. (A command
802 # without an argument should *never* be a destructive action; this
803 # API is fundamentally screwed up; likewise option setting, which
804 # is equally buggered.)
805 # + Added command stack dump on argument of "?" for >, <, or {.
806 # + Added a semi-built-in doc viewer command that calls man with the
807 # proper %Config::Config path (and thus gets caching, man -k, etc),
808 # or else perldoc on obstreperous platforms.
809 # + Added to and rearranged the help information.
810 # + Detected apparent misuse of { ... } to declare a block; this used
811 # to work but now is a command, and mysteriously gave no complaint.
813 # Changes: 1.08: Apr 25, 2001 Jon Eveland <jweveland@yahoo.com>
815 # + This patch to perl5db.pl cleans up formatting issues on the help
816 # summary (h h) screen in the debugger. Mostly columnar alignment
817 # issues, plus converted the printed text to use all spaces, since
818 # tabs don't seem to help much here.
820 # Changes: 1.09: May 19, 2001 Ilya Zakharevich <ilya@math.ohio-state.edu>
821 # Minor bugs corrected;
822 # + Support for auto-creation of new TTY window on startup, either
823 # unconditionally, or if started as a kid of another debugger session;
824 # + New `O'ption CreateTTY
825 # I<CreateTTY> bits control attempts to create a new TTY on events:
827 # 2: debugger is started inside debugger
829 # + Code to auto-create a new TTY window on OS/2 (currently one
830 # extra window per session - need named pipes to have more...);
831 # + Simplified interface for custom createTTY functions (with a backward
832 # compatibility hack); now returns the TTY name to use; return of ''
833 # means that the function reset the I/O handles itself;
834 # + Better message on the semantic of custom createTTY function;
835 # + Convert the existing code to create a TTY into a custom createTTY
837 # + Consistent support for TTY names of the form "TTYin,TTYout";
838 # + Switch line-tracing output too to the created TTY window;
839 # + make `b fork' DWIM with CORE::GLOBAL::fork;
840 # + High-level debugger API cmd_*():
841 # cmd_b_load($filenamepart) # b load filenamepart
842 # cmd_b_line($lineno [, $cond]) # b lineno [cond]
843 # cmd_b_sub($sub [, $cond]) # b sub [cond]
844 # cmd_stop() # Control-C
845 # cmd_d($lineno) # d lineno (B)
846 # The cmd_*() API returns FALSE on failure; in this case it outputs
847 # the error message to the debugging output.
848 # + Low-level debugger API
849 # break_on_load($filename) # b load filename
850 # @files = report_break_on_load() # List files with load-breakpoints
851 # breakable_line_in_filename($name, $from [, $to])
852 # # First breakable line in the
853 # # range $from .. $to. $to defaults
854 # # to $from, and may be less than
856 # breakable_line($from [, $to]) # Same for the current file
857 # break_on_filename_line($name, $lineno [, $cond])
858 # # Set breakpoint,$cond defaults to
860 # break_on_filename_line_range($name, $from, $to [, $cond])
861 # # As above, on the first
862 # # breakable line in range
863 # break_on_line($lineno [, $cond]) # As above, in the current file
864 # break_subroutine($sub [, $cond]) # break on the first breakable line
865 # ($name, $from, $to) = subroutine_filename_lines($sub)
866 # # The range of lines of the text
867 # The low-level API returns TRUE on success, and die()s on failure.
869 # Changes: 1.10: May 23, 2001 Daniel Lewart <d-lewart@uiuc.edu>
871 # + Fixed warnings generated by "perl -dWe 42"
872 # + Corrected spelling errors
873 # + Squeezed Help (h) output into 80 columns
875 # Changes: 1.11: May 24, 2001 David Dyck <dcd@tc.fluke.com>
876 # + Made "x @INC" work like it used to
878 # Changes: 1.12: May 24, 2001 Daniel Lewart <d-lewart@uiuc.edu>
879 # + Fixed warnings generated by "O" (Show debugger options)
880 # + Fixed warnings generated by "p 42" (Print expression)
881 # Changes: 1.13: Jun 19, 2001 Scott.L.Miller@compaq.com
882 # + Added windowSize option
883 # Changes: 1.14: Oct 9, 2001 multiple
884 # + Clean up after itself on VMS (Charles Lane in 12385)
885 # + Adding "@ file" syntax (Peter Scott in 12014)
886 # + Debug reloading selfloaded stuff (Ilya Zakharevich in 11457)
887 # + $^S and other debugger fixes (Ilya Zakharevich in 11120)
888 # + Forgot a my() declaration (Ilya Zakharevich in 11085)
889 # Changes: 1.15: Nov 6, 2001 Michael G Schwern <schwern@pobox.com>
890 # + Updated 1.14 change log
891 # + Added *dbline explainatory comments
892 # + Mentioning perldebguts man page
893 # Changes: 1.16: Feb 15, 2002 Mark-Jason Dominus <mjd@plover.com>
894 # + $onetimeDump improvements
895 # Changes: 1.17: Feb 20, 2002 Richard Foley <richard.foley@rfi.net>
896 # Moved some code to cmd_[.]()'s for clarity and ease of handling,
897 # rationalised the following commands and added cmd_wrapper() to
898 # enable switching between old and frighteningly consistent new
899 # behaviours for diehards: 'o CommandSet=pre580' (sigh...)
900 # a(add), A(del) # action expr (added del by line)
901 # + b(add), B(del) # break [line] (was b,D)
902 # + w(add), W(del) # watch expr (was W,W)
903 # # added del by expr
904 # + h(summary), h h(long) # help (hh) (was h h,h)
905 # + m(methods), M(modules) # ... (was m,v)
906 # + o(option) # lc (was O)
907 # + v(view code), V(view Variables) # ... (was w,V)
908 # Changes: 1.18: Mar 17, 2002 Richard Foley <richard.foley@rfi.net>
909 # + fixed missing cmd_O bug
910 # Changes: 1.19: Mar 29, 2002 Spider Boardman
911 # + Added missing local()s -- DB::DB is called recursively.
912 # Changes: 1.20: Feb 17, 2003 Richard Foley <richard.foley@rfi.net>
913 # + pre'n'post commands no longer trashed with no args
914 # + watch val joined out of eval()
915 # Changes: 1.21: Jun 04, 2003 Joe McMahon <mcmahon@ibiblio.org>
916 # + Added comments and reformatted source. No bug fixes/enhancements.
917 # + Includes cleanup by Robin Barker and Jarkko Hietaniemi.
918 # Changes: 1.22 Jun 09, 2003 Alex Vandiver <alexmv@MIT.EDU>
919 # + Flush stdout/stderr before the debugger prompt is printed.
920 # Changes: 1.23: Dec 21, 2003 Dominique Quatravaux
921 # + Fix a side-effect of bug #24674 in the perl debugger ("odd taint bug")
922 # Changes: 1.24: Mar 03, 2004 Richard Foley <richard.foley@rfi.net>
923 # + Added command to save all debugger commands for sourcing later.
924 # + Added command to display parent inheritance tree of given class.
925 # + Fixed minor newline in history bug.
926 # Changes: 1.25: Apr 17, 2004 Richard Foley <richard.foley@rfi.net>
927 # + Fixed option bug (setting invalid options + not recognising valid short forms)
928 # Changes: 1.26: Apr 22, 2004 Richard Foley <richard.foley@rfi.net>
929 # + unfork the 5.8.x and 5.9.x debuggers.
930 # + whitespace and assertions call cleanup across versions
931 # + H * deletes (resets) history
932 # + i now handles Class + blessed objects
933 # Changes: 1.27: May 09, 2004 Richard Foley <richard.foley@rfi.net>
934 # + updated pod page references - clunky.
935 # + removed windowid restriction for forking into an xterm.
936 # + more whitespace again.
937 # + wrapped restart and enabled rerun [-n] (go back n steps) command.
938 # Changes: 1.28: Oct 12, 2004 Richard Foley <richard.foley@rfi.net>
939 # + Added threads support (inc. e and E commands)
940 # Changes: 1.29: Nov 28, 2006 Bo Lindbergh <blgl@hagernas.com>
941 # + Added macosx_get_fork_TTY support
942 # Changes: 1.30: Mar 06, 2007 Andreas Koenig <andk@cpan.org>
943 # + Added HistFile, HistSize
945 # + Remove support for assertions and -A
946 # + stop NEXT::AUTOLOAD from emitting warnings under the debugger. RT #25053
947 # + "update for Mac OS X 10.5" [finding the tty device]
948 # + "What I needed to get the forked debugger to work" [on VMS]
949 # + [perl #57016] debugger: o warn=0 die=0 ignored
950 # + Note, but don't use, PERLDBf_SAVESRC
951 # + Fix #7013: lvalue subs not working inside debugger
952 # Changes: 1.32: Jun 03, 2009 Jonathan Leto <jonathan@leto.net>
953 # + Fix bug where a key _< with undefined value was put into the symbol table
954 # + when the $filename variable is not set
955 ########################################################################
957 =head1 DEBUGGER INITIALIZATION
959 The debugger starts up in phases.
963 First, it initializes the environment it wants to run in: turning off
964 warnings during its own compilation, defining variables which it will need
965 to avoid warnings later, setting itself up to not exit when the program
966 terminates, and defaulting to printing return values for the C<r> command.
970 # Needed for the statement after exec():
972 # This BEGIN block is simply used to switch off warnings during debugger
973 # compiliation. Probably it would be better practice to fix the warnings,
974 # but this is how it's done at the moment.
979 } # Switch compilation warnings off until another BEGIN.
981 local ($^W) = 0; # Switch run-time warnings off during init.
983 =head2 THREADS SUPPORT
985 If we are running under a threaded Perl, we require threads and threads::shared
986 if the environment variable C<PERL5DB_THREADED> is set, to enable proper
987 threaded debugger control. C<-dt> can also be used to set this.
989 Each new thread will be announced and the debugger prompt will always inform
990 you of each new thread created. It will also indicate the thread id in which
991 we are currently running within the prompt like this:
995 Where C<[tid]> is an integer thread id and C<$i> is the familiar debugger
996 command prompt. The prompt will show: C<[0]> when running under threads, but
997 not actually in a thread. C<[tid]> is consistent with C<gdb> usage.
999 While running under threads, when you set or delete a breakpoint (etc.), this
1000 will apply to all threads, not just the currently running one. When you are
1001 in a currently executing thread, you will stay there until it completes. With
1002 the current implementation it is not currently possible to hop from one thread
1005 The C<e> and C<E> commands are currently fairly minimal - see C<h e> and C<h E>.
1007 Note that threading support was built into the debugger as of Perl version
1008 C<5.8.6> and debugger version C<1.2.8>.
1013 # ensure we can share our non-threaded variables or no-op
1014 if ($ENV{PERL5DB_THREADED}) {
1016 require threads::shared;
1017 import threads::shared qw(share);
1021 print "Threads support enabled\n";
1028 # This would probably be better done with "use vars", but that wasn't around
1029 # when this code was originally written. (Neither was "use strict".) And on
1030 # the principle of not fiddling with something that was working, this was
1033 # These variables control the execution of 'dumpvar.pl'.
1034 $dumpvar::hashDepth,
1035 $dumpvar::arrayDepth,
1036 $dumpvar::dumpDBFiles,
1037 $dumpvar::dumpPackages,
1038 $dumpvar::quoteHighBit,
1039 $dumpvar::printUndef,
1040 $dumpvar::globPrint,
1041 $dumpvar::usageOnly,
1043 # used to save @ARGV and extract any debugger-related flags.
1046 # used to control die() reporting in diesignal()
1049 # used to prevent multiple entries to diesignal()
1050 # (if for instance diesignal() itself dies)
1053 # used to prevent the debugger from running nonstop
1059 # without threads, $filename is not defined until DB::DB is called
1060 foreach my $k (keys (%INC)) {
1061 &share(\$main::{'_<'.$filename}) if defined $filename;
1064 # Command-line + PERLLIB:
1065 # Save the contents of @INC before they are modified elsewhere.
1068 # This was an attempt to clear out the previous values of various
1069 # trapped errors. Apparently it didn't help. XXX More info needed!
1070 # $prevwarn = $prevdie = $prevbus = $prevsegv = ''; # Does not help?!
1072 # We set these variables to safe values. We don't want to blindly turn
1073 # off warnings, because other packages may still want them.
1074 $trace = $signal = $single = 0; # Uninitialized warning suppression
1075 # (local $^W cannot help - other packages!).
1077 # Default to not exiting when program finishes; print the return
1078 # value when the 'r' command is used to return from a subroutine.
1079 $inhibit_exit = $option{PrintRet} = 1;
1081 =head1 OPTION PROCESSING
1083 The debugger's options are actually spread out over the debugger itself and
1084 C<dumpvar.pl>; some of these are variables to be set, while others are
1085 subs to be called with a value. To try to make this a little easier to
1086 manage, the debugger uses a few data structures to define what options
1087 are legal and how they are to be processed.
1089 First, the C<@options> array defines the I<names> of all the options that
1095 CommandSet HistFile HistSize
1096 hashDepth arrayDepth dumpDepth
1097 DumpDBFiles DumpPackages DumpReused
1098 compactDump veryCompact quote
1099 HighBit undefPrint globPrint
1100 PrintRet UsageOnly frame
1102 ReadLine NonStop LineInfo
1103 maxTraceLen recallCommand ShellBang
1104 pager tkRunning ornaments
1105 signalLevel warnLevel dieLevel
1106 inhibit_exit ImmediateStop bareStringify
1107 CreateTTY RemotePort windowSize
1111 @RememberOnROptions = qw(DollarCaretP);
1115 Second, C<optionVars> lists the variables that each option uses to save its
1121 hashDepth => \$dumpvar::hashDepth,
1122 arrayDepth => \$dumpvar::arrayDepth,
1123 CommandSet => \$CommandSet,
1124 DumpDBFiles => \$dumpvar::dumpDBFiles,
1125 DumpPackages => \$dumpvar::dumpPackages,
1126 DumpReused => \$dumpvar::dumpReused,
1127 HighBit => \$dumpvar::quoteHighBit,
1128 undefPrint => \$dumpvar::printUndef,
1129 globPrint => \$dumpvar::globPrint,
1130 UsageOnly => \$dumpvar::usageOnly,
1131 CreateTTY => \$CreateTTY,
1132 bareStringify => \$dumpvar::bareStringify,
1134 AutoTrace => \$trace,
1135 inhibit_exit => \$inhibit_exit,
1136 maxTraceLen => \$maxtrace,
1137 ImmediateStop => \$ImmediateStop,
1138 RemotePort => \$remoteport,
1139 windowSize => \$window,
1140 HistFile => \$histfile,
1141 HistSize => \$histsize,
1146 Third, C<%optionAction> defines the subroutine to be called to process each
1152 compactDump => \&dumpvar::compactDump,
1153 veryCompact => \&dumpvar::veryCompact,
1154 quote => \&dumpvar::quote,
1157 ReadLine => \&ReadLine,
1158 NonStop => \&NonStop,
1159 LineInfo => \&LineInfo,
1160 recallCommand => \&recallCommand,
1161 ShellBang => \&shellBang,
1163 signalLevel => \&signalLevel,
1164 warnLevel => \&warnLevel,
1165 dieLevel => \&dieLevel,
1166 tkRunning => \&tkRunning,
1167 ornaments => \&ornaments,
1168 RemotePort => \&RemotePort,
1169 DollarCaretP => \&DollarCaretP,
1174 Last, the C<%optionRequire> notes modules that must be C<require>d if an
1179 # Note that this list is not complete: several options not listed here
1180 # actually require that dumpvar.pl be loaded for them to work, but are
1181 # not in the table. A subsequent patch will correct this problem; for
1182 # the moment, we're just recommenting, and we are NOT going to change
1185 compactDump => 'dumpvar.pl',
1186 veryCompact => 'dumpvar.pl',
1187 quote => 'dumpvar.pl',
1192 There are a number of initialization-related variables which can be set
1193 by putting code to set them in a BEGIN block in the C<PERL5DB> environment
1194 variable. These are:
1198 =item C<$rl> - readline control XXX needs more explanation
1200 =item C<$warnLevel> - whether or not debugger takes over warning handling
1202 =item C<$dieLevel> - whether or not debugger takes over die handling
1204 =item C<$signalLevel> - whether or not debugger takes over signal handling
1206 =item C<$pre> - preprompt actions (array reference)
1208 =item C<$post> - postprompt actions (array reference)
1212 =item C<$CreateTTY> - whether or not to create a new TTY for this debugger
1214 =item C<$CommandSet> - which command set to use (defaults to new, documented set)
1220 # These guys may be defined in $ENV{PERL5DB} :
1221 $rl = 1 unless defined $rl;
1222 $warnLevel = 1 unless defined $warnLevel;
1223 $dieLevel = 1 unless defined $dieLevel;
1224 $signalLevel = 1 unless defined $signalLevel;
1225 $pre = [] unless defined $pre;
1226 $post = [] unless defined $post;
1227 $pretype = [] unless defined $pretype;
1228 $CreateTTY = 3 unless defined $CreateTTY;
1229 $CommandSet = '580' unless defined $CommandSet;
1234 share($signalLevel);
1244 The default C<die>, C<warn>, and C<signal> handlers are set up.
1248 warnLevel($warnLevel);
1249 dieLevel($dieLevel);
1250 signalLevel($signalLevel);
1254 The pager to be used is needed next. We try to get it from the
1255 environment first. If it's not defined there, we try to find it in
1256 the Perl C<Config.pm>. If it's not there, we default to C<more>. We
1257 then call the C<pager()> function to save the pager name.
1261 # This routine makes sure $pager is set up so that '|' can use it.
1264 # If PAGER is defined in the environment, use it.
1268 # If not, see if Config.pm defines it.
1269 : eval { require Config }
1270 && defined $Config::Config{pager}
1271 ? $Config::Config{pager}
1273 # If not, fall back to 'more'.
1276 unless defined $pager;
1280 We set up the command to be used to access the man pages, the command
1281 recall character (C<!> unless otherwise defined) and the shell escape
1282 character (C<!> unless otherwise defined). Yes, these do conflict, and
1283 neither works in the debugger at the moment.
1289 # Set up defaults for command recall and shell escape (note:
1290 # these currently don't work in linemode debugging).
1291 &recallCommand("!") unless defined $prc;
1292 &shellBang("!") unless defined $psh;
1296 We then set up the gigantic string containing the debugger help.
1297 We also set the limit on the number of arguments we'll display during a
1304 # If we didn't get a default for the length of eval/stack trace args,
1306 $maxtrace = 400 unless defined $maxtrace;
1308 =head2 SETTING UP THE DEBUGGER GREETING
1310 The debugger I<greeting> helps to inform the user how many debuggers are
1311 running, and whether the current debugger is the primary or a child.
1313 If we are the primary, we just hang onto our pid so we'll have it when
1314 or if we start a child debugger. If we are a child, we'll set things up
1315 so we'll have a unique greeting and so the parent will give us our own
1318 We save the current contents of the C<PERLDB_PIDS> environment variable
1319 because we mess around with it. We'll also need to hang onto it because
1320 we'll need it if we restart.
1322 Child debuggers make a label out of the current PID structure recorded in
1323 PERLDB_PIDS plus the new PID. They also mark themselves as not having a TTY
1324 yet so the parent will give them one later via C<resetterm()>.
1328 # Save the current contents of the environment; we're about to
1329 # much with it. We'll need this if we have to restart.
1330 $ini_pids = $ENV{PERLDB_PIDS};
1332 if ( defined $ENV{PERLDB_PIDS} ) {
1334 # We're a child. Make us a label out of the current PID structure
1335 # recorded in PERLDB_PIDS plus our (new) PID. Mark us as not having
1336 # a term yet so the parent will give us one later via resetterm().
1338 my $env_pids = $ENV{PERLDB_PIDS};
1339 $pids = "[$env_pids]";
1341 # Unless we are on OpenVMS, all programs under the DCL shell run under
1344 if (($^O eq 'VMS') && ($env_pids =~ /\b$$\b/)) {
1348 $ENV{PERLDB_PIDS} .= "->$$";
1352 } ## end if (defined $ENV{PERLDB_PIDS...
1355 # We're the parent PID. Initialize PERLDB_PID in case we end up with a
1356 # child debugger, and mark us as the parent, so we'll know to set up
1357 # more TTY's is we have to.
1358 $ENV{PERLDB_PIDS} = "$$";
1365 # Sets up $emacs as a synonym for $slave_editor.
1366 *emacs = $slave_editor if $slave_editor; # May be used in afterinit()...
1368 =head2 READING THE RC FILE
1370 The debugger will read a file of initialization options if supplied. If
1371 running interactively, this is C<.perldb>; if not, it's C<perldb.ini>.
1375 # As noted, this test really doesn't check accurately that the debugger
1376 # is running at a terminal or not.
1378 my $dev_tty = '/dev/tty';
1379 $dev_tty = 'TT:' if ($^O eq 'VMS');
1380 if ( -e $dev_tty ) { # this is the wrong metric!
1381 $rcfile = ".perldb";
1384 $rcfile = "perldb.ini";
1389 The debugger does a safety test of the file to be read. It must be owned
1390 either by the current user or root, and must only be writable by the owner.
1394 # This wraps a safety test around "do" to read and evaluate the init file.
1396 # This isn't really safe, because there's a race
1397 # between checking and opening. The solution is to
1398 # open and fstat the handle, but then you have to read and
1399 # eval the contents. But then the silly thing gets
1400 # your lexical scope, which is unfortunate at best.
1404 # Just exactly what part of the word "CORE::" don't you understand?
1405 local $SIG{__WARN__};
1406 local $SIG{__DIE__};
1408 unless ( is_safe_file($file) ) {
1409 CORE::warn <<EO_GRIPE;
1410 perldb: Must not source insecure rcfile $file.
1411 You or the superuser must be the owner, and it must not
1412 be writable by anyone but its owner.
1415 } ## end unless (is_safe_file($file...
1418 CORE::warn("perldb: couldn't parse $file: $@") if $@;
1419 } ## end sub safe_do
1421 # This is the safety test itself.
1423 # Verifies that owner is either real user or superuser and that no
1424 # one but owner may write to it. This function is of limited use
1425 # when called on a path instead of upon a handle, because there are
1426 # no guarantees that filename (by dirent) whose file (by ino) is
1427 # eventually accessed is the same as the one tested.
1428 # Assumes that the file's existence is not in doubt.
1431 stat($path) || return; # mysteriously vaporized
1432 my ( $dev, $ino, $mode, $nlink, $uid, $gid ) = stat(_);
1434 return 0 if $uid != 0 && $uid != $<;
1435 return 0 if $mode & 022;
1437 } ## end sub is_safe_file
1439 # If the rcfile (whichever one we decided was the right one to read)
1440 # exists, we safely do it.
1442 safe_do("./$rcfile");
1445 # If there isn't one here, try the user's home directory.
1446 elsif ( defined $ENV{HOME} && -f "$ENV{HOME}/$rcfile" ) {
1447 safe_do("$ENV{HOME}/$rcfile");
1450 # Else try the login directory.
1451 elsif ( defined $ENV{LOGDIR} && -f "$ENV{LOGDIR}/$rcfile" ) {
1452 safe_do("$ENV{LOGDIR}/$rcfile");
1455 # If the PERLDB_OPTS variable has options in it, parse those out next.
1456 if ( defined $ENV{PERLDB_OPTS} ) {
1457 parse_options( $ENV{PERLDB_OPTS} );
1462 The last thing we do during initialization is determine which subroutine is
1463 to be used to obtain a new terminal when a new debugger is started. Right now,
1464 the debugger only handles X Windows, OS/2, and Mac OS X (darwin).
1468 # Set up the get_fork_TTY subroutine to be aliased to the proper routine.
1469 # Works if you're running an xterm or xterm-like window, or you're on
1470 # OS/2, or on Mac OS X. This may need some expansion.
1472 if (not defined &get_fork_TTY) # only if no routine exists
1474 if (defined $ENV{TERM} # If we know what kind
1475 # of terminal this is,
1476 and $ENV{TERM} eq 'xterm' # and it's an xterm,
1477 and defined $ENV{DISPLAY} # and what display it's on,
1480 *get_fork_TTY = \&xterm_get_fork_TTY; # use the xterm version
1482 elsif ( $^O eq 'os2' ) { # If this is OS/2,
1483 *get_fork_TTY = \&os2_get_fork_TTY; # use the OS/2 version
1485 elsif ( $^O eq 'darwin' # If this is Mac OS X
1486 and defined $ENV{TERM_PROGRAM} # and we're running inside
1487 and $ENV{TERM_PROGRAM}
1488 eq 'Apple_Terminal' # Terminal.app
1491 *get_fork_TTY = \&macosx_get_fork_TTY; # use the Mac OS X version
1493 } ## end if (not defined &get_fork_TTY...
1495 # untaint $^O, which may have been tainted by the last statement.
1496 # see bug [perl #24674]
1500 # Here begin the unreadable code. It needs fixing.
1502 =head2 RESTART PROCESSING
1504 This section handles the restart command. When the C<R> command is invoked, it
1505 tries to capture all of the state it can into environment variables, and
1506 then sets C<PERLDB_RESTART>. When we start executing again, we check to see
1507 if C<PERLDB_RESTART> is there; if so, we reload all the information that
1508 the R command stuffed into the environment variables.
1510 PERLDB_RESTART - flag only, contains no restart data itself.
1511 PERLDB_HIST - command history, if it's available
1512 PERLDB_ON_LOAD - breakpoints set by the rc file
1513 PERLDB_POSTPONE - subs that have been loaded/not executed, and have actions
1514 PERLDB_VISITED - files that had breakpoints
1515 PERLDB_FILE_... - breakpoints for a file
1516 PERLDB_OPT - active options
1517 PERLDB_INC - the original @INC
1518 PERLDB_PRETYPE - preprompt debugger actions
1519 PERLDB_PRE - preprompt Perl code
1520 PERLDB_POST - post-prompt Perl code
1521 PERLDB_TYPEAHEAD - typeahead captured by readline()
1523 We chug through all these variables and plug the values saved in them
1524 back into the appropriate spots in the debugger.
1528 if ( exists $ENV{PERLDB_RESTART} ) {
1530 # We're restarting, so we don't need the flag that says to restart anymore.
1531 delete $ENV{PERLDB_RESTART};
1534 @hist = get_list('PERLDB_HIST');
1535 %break_on_load = get_list("PERLDB_ON_LOAD");
1536 %postponed = get_list("PERLDB_POSTPONE");
1540 share(%break_on_load);
1543 # restore breakpoints/actions
1544 my @had_breakpoints = get_list("PERLDB_VISITED");
1545 for ( 0 .. $#had_breakpoints ) {
1546 my %pf = get_list("PERLDB_FILE_$_");
1547 $postponed_file{ $had_breakpoints[$_] } = \%pf if %pf;
1551 my %opt = get_list("PERLDB_OPT");
1553 while ( ( $opt, $val ) = each %opt ) {
1554 $val =~ s/[\\\']/\\$1/g;
1555 parse_options("$opt'$val'");
1558 # restore original @INC
1559 @INC = get_list("PERLDB_INC");
1562 # return pre/postprompt actions and typeahead buffer
1563 $pretype = [ get_list("PERLDB_PRETYPE") ];
1564 $pre = [ get_list("PERLDB_PRE") ];
1565 $post = [ get_list("PERLDB_POST") ];
1566 @typeahead = get_list( "PERLDB_TYPEAHEAD", @typeahead );
1567 } ## end if (exists $ENV{PERLDB_RESTART...
1569 =head2 SETTING UP THE TERMINAL
1571 Now, we'll decide how the debugger is going to interact with the user.
1572 If there's no TTY, we set the debugger to run non-stop; there's not going
1573 to be anyone there to enter commands.
1584 If there is a TTY, we have to determine who it belongs to before we can
1585 proceed. If this is a slave editor or graphical debugger (denoted by
1586 the first command-line switch being '-emacs'), we shift this off and
1587 set C<$rl> to 0 (XXX ostensibly to do straight reads).
1593 # Is Perl being run from a slave editor or graphical debugger?
1594 # If so, don't use readline, and set $slave_editor = 1.
1596 ( ( defined $main::ARGV[0] ) and ( $main::ARGV[0] eq '-emacs' ) );
1597 $rl = 0, shift(@main::ARGV) if $slave_editor;
1599 #require Term::ReadLine;
1603 We then determine what the console should be on various systems:
1607 =item * Cygwin - We use C<stdin> instead of a separate device.
1611 if ( $^O eq 'cygwin' ) {
1613 # /dev/tty is binary. use stdin for textmode
1617 =item * Unix - use C</dev/tty>.
1621 elsif ( -e "/dev/tty" ) {
1622 $console = "/dev/tty";
1625 =item * Windows or MSDOS - use C<con>.
1629 elsif ( $^O eq 'dos' or -e "con" or $^O eq 'MSWin32' ) {
1633 =item * MacOS - use C<Dev:Console:Perl Debug> if this is the MPW version; C<Dev:
1636 Note that Mac OS X returns C<darwin>, not C<MacOS>. Also note that the debugger doesn't do anything special for C<darwin>. Maybe it should.
1640 elsif ( $^O eq 'MacOS' ) {
1641 if ( $MacPerl::Version !~ /MPW/ ) {
1643 "Dev:Console:Perl Debug"; # Separate window for application
1646 $console = "Dev:Console";
1648 } ## end elsif ($^O eq 'MacOS')
1650 =item * VMS - use C<sys$command>.
1656 # everything else is ...
1657 $console = "sys\$command";
1664 Several other systems don't use a specific console. We C<undef $console>
1665 for those (Windows using a slave editor/graphical debugger, NetWare, OS/2
1666 with a slave editor, Epoc).
1670 if ( ( $^O eq 'MSWin32' ) and ( $slave_editor or defined $ENV{EMACS} ) ) {
1672 # /dev/tty is binary. use stdin for textmode
1676 if ( $^O eq 'NetWare' ) {
1678 # /dev/tty is binary. use stdin for textmode
1682 # In OS/2, we need to use STDIN to get textmode too, even though
1683 # it pretty much looks like Unix otherwise.
1684 if ( defined $ENV{OS2_SHELL} and ( $slave_editor or $ENV{WINDOWID} ) )
1689 # EPOC also falls into the 'got to use STDIN' camp.
1690 if ( $^O eq 'epoc' ) {
1696 If there is a TTY hanging around from a parent, we use that as the console.
1700 $console = $tty if defined $tty;
1702 =head2 SOCKET HANDLING
1704 The debugger is capable of opening a socket and carrying out a debugging
1705 session over the socket.
1707 If C<RemotePort> was defined in the options, the debugger assumes that it
1708 should try to start a debugging session on that port. It builds the socket
1709 and then tries to connect the input and output filehandles to it.
1713 # Handle socket stuff.
1715 if ( defined $remoteport ) {
1717 # If RemotePort was defined in the options, connect input and output
1720 $OUT = new IO::Socket::INET(
1722 PeerAddr => $remoteport,
1725 if ( !$OUT ) { die "Unable to connect to remote host: $remoteport\n"; }
1727 } ## end if (defined $remoteport)
1731 If no C<RemotePort> was defined, and we want to create a TTY on startup,
1732 this is probably a situation where multiple debuggers are running (for example,
1733 a backticked command that starts up another debugger). We create a new IN and
1734 OUT filehandle, and do the necessary mojo to create a new TTY if we know how
1742 # Two debuggers running (probably a system or a backtick that invokes
1743 # the debugger itself under the running one). create a new IN and OUT
1744 # filehandle, and do the necessary mojo to create a new tty if we
1745 # know how, and we can.
1746 create_IN_OUT(4) if $CreateTTY & 4;
1749 # If we have a console, check to see if there are separate ins and
1750 # outs to open. (They are assumed identical if not.)
1752 my ( $i, $o ) = split /,/, $console;
1753 $o = $i unless defined $o;
1755 # read/write on in, or just read, or read on STDIN.
1757 || open( IN, "<$i" )
1758 || open( IN, "<&STDIN" );
1760 # read/write/create/clobber out, or write/create/clobber out,
1761 # or merge with STDERR, or merge with STDOUT.
1763 || open( OUT, ">$o" )
1764 || open( OUT, ">&STDERR" )
1765 || open( OUT, ">&STDOUT" ); # so we don't dongle stdout
1767 } ## end if ($console)
1768 elsif ( not defined $console ) {
1770 # No console. Open STDIN.
1771 open( IN, "<&STDIN" );
1773 # merge with STDERR, or with STDOUT.
1774 open( OUT, ">&STDERR" )
1775 || open( OUT, ">&STDOUT" ); # so we don't dongle stdout
1776 $console = 'STDIN/OUT';
1777 } ## end elsif (not defined $console)
1779 # Keep copies of the filehandles so that when the pager runs, it
1780 # can close standard input without clobbering ours.
1781 $IN = \*IN, $OUT = \*OUT if $console or not defined $console;
1782 } ## end elsif (from if(defined $remoteport))
1784 # Unbuffer DB::OUT. We need to see responses right away.
1785 my $previous = select($OUT);
1786 $| = 1; # for DB::OUT
1789 # Line info goes to debugger output unless pointed elsewhere.
1790 # Pointing elsewhere makes it possible for slave editors to
1791 # keep track of file and position. We have both a filehandle
1792 # and a I/O description to keep track of.
1793 $LINEINFO = $OUT unless defined $LINEINFO;
1794 $lineinfo = $console unless defined $lineinfo;
1795 # share($LINEINFO); # <- unable to share globs
1800 To finish initialization, we show the debugger greeting,
1801 and then call the C<afterinit()> subroutine if there is one.
1805 # Show the debugger greeting.
1806 $header =~ s/.Header: ([^,]+),v(\s+\S+\s+\S+).*$/$1$2/;
1807 unless ($runnonstop) {
1810 if ( $term_pid eq '-1' ) {
1811 print $OUT "\nDaughter DB session started...\n";
1814 print $OUT "\nLoading DB routines from $header\n";
1817 $slave_editor ? "enabled" : "available", ".\n"
1820 "\nEnter h or `h h' for help, or `$doccmd perldebug' for more help.\n\n";
1821 } ## end else [ if ($term_pid eq '-1')
1822 } ## end unless ($runnonstop)
1823 } ## end else [ if ($notty)
1825 # XXX This looks like a bug to me.
1826 # Why copy to @ARGS and then futz with @args?
1829 # Make sure backslashes before single quotes are stripped out, and
1830 # keep args unless they are numeric (XXX why?)
1831 # s/\'/\\\'/g; # removed while not justified understandably
1832 # s/(.*)/'$1'/ unless /^-?[\d.]+$/; # ditto
1835 # If there was an afterinit() sub defined, call it. It will get
1836 # executed in our scope, so it can fiddle with debugger globals.
1837 if ( defined &afterinit ) { # May be defined in $rcfile
1841 # Inform us about "Stack dump during die enabled ..." in dieLevel().
1844 ############################################################ Subroutines
1850 This gigantic subroutine is the heart of the debugger. Called before every
1851 statement, its job is to determine if a breakpoint has been reached, and
1852 stop if so; read commands from the user, parse them, and execute
1853 them, and then send execution off to the next statement.
1855 Note that the order in which the commands are processed is very important;
1856 some commands earlier in the loop will actually alter the C<$cmd> variable
1857 to create other commands to be executed later. This is all highly I<optimized>
1858 but can be confusing. Check the comments for each C<$cmd ... && do {}> to
1859 see what's happening in any given command.
1865 # lock the debugger and get the thread id for the prompt
1868 if ($ENV{PERL5DB_THREADED}) {
1869 $tid = eval { "[".threads->tid."]" };
1872 # Check for whether we should be running continuously or not.
1873 # _After_ the perl program is compiled, $single is set to 1:
1874 if ( $single and not $second_time++ ) {
1876 # Options say run non-stop. Run until we get an interrupt.
1877 if ($runnonstop) { # Disable until signal
1878 # If there's any call stack in place, turn off single
1879 # stepping into subs throughout the stack.
1880 for ( $i = 0 ; $i <= $stack_depth ; ) {
1881 $stack[ $i++ ] &= ~1;
1884 # And we are now no longer in single-step mode.
1887 # If we simply returned at this point, we wouldn't get
1888 # the trace info. Fall on through.
1890 } ## end if ($runnonstop)
1892 elsif ($ImmediateStop) {
1894 # We are supposed to stop here; XXX probably a break.
1895 $ImmediateStop = 0; # We've processed it; turn it off
1896 $signal = 1; # Simulate an interrupt to force
1897 # us into the command loop
1899 } ## end if ($single and not $second_time...
1901 # If we're in single-step mode, or an interrupt (real or fake)
1902 # has occurred, turn off non-stop mode.
1903 $runnonstop = 0 if $single or $signal;
1905 # Preserve current values of $@, $!, $^E, $,, $/, $\, $^W.
1906 # The code being debugged may have altered them.
1909 # Since DB::DB gets called after every line, we can use caller() to
1910 # figure out where we last were executing. Sneaky, eh? This works because
1911 # caller is returning all the extra information when called from the
1913 local ( $package, $filename, $line ) = caller;
1914 local $filename_ini = $filename;
1916 # set up the context for DB::eval, so it can properly execute
1917 # code on behalf of the user. We add the package in so that the
1918 # code is eval'ed in the proper package (not in the debugger!).
1919 local $usercontext =
1920 '($@, $!, $^E, $,, $/, $\, $^W) = @saved;' . "package $package;";
1922 # Create an alias to the active file magical array to simplify
1924 local (*dbline) = $main::{ '_<' . $filename };
1926 # we need to check for pseudofiles on Mac OS (these are files
1927 # not attached to a filename, but instead stored in Dev:Pseudo)
1928 if ( $^O eq 'MacOS' && $#dbline < 0 ) {
1929 $filename_ini = $filename = 'Dev:Pseudo';
1930 *dbline = $main::{ '_<' . $filename };
1933 # Last line in the program.
1934 local $max = $#dbline;
1936 # if we have something here, see if we should break.
1938 && ( ( $stop, $action ) = split( /\0/, $dbline{$line} ) ) )
1941 # Stop if the stop criterion says to just stop.
1942 if ( $stop eq '1' ) {
1946 # It's a conditional stop; eval it in the user's context and
1947 # see if we should stop. If so, remove the one-time sigil.
1949 $evalarg = "\$DB::signal |= 1 if do {$stop}";
1951 $dbline{$line} =~ s/;9($|\0)/$1/;
1953 } ## end if ($dbline{$line} && ...
1955 # Preserve the current stop-or-not, and see if any of the W
1956 # (watch expressions) has changed.
1957 my $was_signal = $signal;
1959 # If we have any watch expressions ...
1961 for ( my $n = 0 ; $n <= $#to_watch ; $n++ ) {
1962 $evalarg = $to_watch[$n];
1963 local $onetimeDump; # Tell DB::eval() to not output results
1965 # Fix context DB::eval() wants to return an array, but
1966 # we need a scalar here.
1967 my ($val) = join( "', '", &eval );
1968 $val = ( ( defined $val ) ? "'$val'" : 'undef' );
1971 if ( $val ne $old_watch[$n] ) {
1973 # Yep! Show the difference, and fake an interrupt.
1976 Watchpoint $n:\t$to_watch[$n] changed:
1977 old value:\t$old_watch[$n]
1980 $old_watch[$n] = $val;
1981 } ## end if ($val ne $old_watch...
1982 } ## end for (my $n = 0 ; $n <= ...
1983 } ## end if ($trace & 2)
1985 =head2 C<watchfunction()>
1987 C<watchfunction()> is a function that can be defined by the user; it is a
1988 function which will be run on each entry to C<DB::DB>; it gets the
1989 current package, filename, and line as its parameters.
1991 The watchfunction can do anything it likes; it is executing in the
1992 debugger's context, so it has access to all of the debugger's internal
1993 data structures and functions.
1995 C<watchfunction()> can control the debugger's actions. Any of the following
1996 will cause the debugger to return control to the user's program after
1997 C<watchfunction()> executes:
2003 Returning a false value from the C<watchfunction()> itself.
2007 Altering C<$single> to a false value.
2011 Altering C<$signal> to a false value.
2015 Turning off the C<4> bit in C<$trace> (this also disables the
2016 check for C<watchfunction()>. This can be done with
2024 # If there's a user-defined DB::watchfunction, call it with the
2025 # current package, filename, and line. The function executes in
2027 if ( $trace & 4 ) { # User-installed watch
2029 if watchfunction( $package, $filename, $line )
2032 and not( $trace & ~4 );
2033 } ## end if ($trace & 4)
2035 # Pick up any alteration to $signal in the watchfunction, and
2036 # turn off the signal now.
2037 $was_signal = $signal;
2040 =head2 GETTING READY TO EXECUTE COMMANDS
2042 The debugger decides to take control if single-step mode is on, the
2043 C<t> command was entered, or the user generated a signal. If the program
2044 has fallen off the end, we set things up so that entering further commands
2045 won't cause trouble, and we say that the program is over.
2049 # Check to see if we should grab control ($single true,
2050 # trace set appropriately, or we got a signal).
2051 if ( $single || ( $trace & 1 ) || $was_signal ) {
2053 # Yes, grab control.
2054 if ($slave_editor) {
2056 # Tell the editor to update its position.
2057 $position = "\032\032$filename:$line:0\n";
2058 print_lineinfo($position);
2063 Special check: if we're in package C<DB::fake>, we've gone through the
2064 C<END> block at least once. We set up everything so that we can continue
2065 to enter commands and have a valid context to be in.
2069 elsif ( $package eq 'DB::fake' ) {
2071 # Fallen off the end already.
2074 Debugged program terminated. Use B<q> to quit or B<R> to restart,
2075 use B<o> I<inhibit_exit> to avoid stopping after program termination,
2076 B<h q>, B<h R> or B<h o> to get additional info.
2079 # Set the DB::eval context appropriately.
2082 '($@, $!, $^E, $,, $/, $\, $^W) = @saved;'
2083 . "package $package;"; # this won't let them modify, alas
2084 } ## end elsif ($package eq 'DB::fake')
2088 If the program hasn't finished executing, we scan forward to the
2089 next executable line, print that out, build the prompt from the file and line
2090 number information, and print that.
2096 # Still somewhere in the midst of execution. Set up the
2098 $sub =~ s/\'/::/; # Swap Perl 4 package separators (') to
2099 # Perl 5 ones (sorry, we don't print Klingon
2102 $prefix = $sub =~ /::/ ? "" : "${'package'}::";
2103 $prefix .= "$sub($filename:";
2104 $after = ( $dbline[$line] =~ /\n$/ ? '' : "\n" );
2106 # Break up the prompt if it's really long.
2107 if ( length($prefix) > 30 ) {
2108 $position = "$prefix$line):\n$line:\t$dbline[$line]$after";
2114 $position = "$prefix$line$infix$dbline[$line]$after";
2117 # Print current line info, indenting if necessary.
2119 print_lineinfo( ' ' x $stack_depth,
2120 "$line:\t$dbline[$line]$after" );
2123 print_lineinfo($position);
2126 # Scan forward, stopping at either the end or the next
2128 for ( $i = $line + 1 ; $i <= $max && $dbline[$i] == 0 ; ++$i )
2131 # Drop out on null statements, block closers, and comments.
2132 last if $dbline[$i] =~ /^\s*[\;\}\#\n]/;
2134 # Drop out if the user interrupted us.
2137 # Append a newline if the line doesn't have one. Can happen
2138 # in eval'ed text, for instance.
2139 $after = ( $dbline[$i] =~ /\n$/ ? '' : "\n" );
2141 # Next executable line.
2142 $incr_pos = "$prefix$i$infix$dbline[$i]$after";
2143 $position .= $incr_pos;
2146 # Print it indented if tracing is on.
2147 print_lineinfo( ' ' x $stack_depth,
2148 "$i:\t$dbline[$i]$after" );
2151 print_lineinfo($incr_pos);
2153 } ## end for ($i = $line + 1 ; $i...
2154 } ## end else [ if ($slave_editor)
2155 } ## end if ($single || ($trace...
2159 If there's an action to be executed for the line we stopped at, execute it.
2160 If there are any preprompt actions, execute those as well.
2164 # If there's an action, do it now.
2165 $evalarg = $action, &eval if $action;
2167 # Are we nested another level (e.g., did we evaluate a function
2168 # that had a breakpoint in it at the debugger prompt)?
2169 if ( $single || $was_signal ) {
2171 # Yes, go down a level.
2172 local $level = $level + 1;
2174 # Do any pre-prompt actions.
2175 foreach $evalarg (@$pre) {
2179 # Complain about too much recursion if we passed the limit.
2180 print $OUT $stack_depth . " levels deep in subroutine calls!\n"
2183 # The line we're currently on. Set $incr to -1 to stay here
2184 # until we get a command that tells us to advance.
2186 $incr = -1; # for backward motion.
2188 # Tack preprompt debugger actions ahead of any actual input.
2189 @typeahead = ( @$pretype, @typeahead );
2191 =head2 WHERE ARE WE?
2193 XXX Relocate this section?
2195 The debugger normally shows the line corresponding to the current line of
2196 execution. Sometimes, though, we want to see the next line, or to move elsewhere
2197 in the file. This is done via the C<$incr>, C<$start>, and C<$max> variables.
2199 C<$incr> controls by how many lines the I<current> line should move forward
2200 after a command is executed. If set to -1, this indicates that the I<current>
2201 line shouldn't change.
2203 C<$start> is the I<current> line. It is used for things like knowing where to
2204 move forwards or backwards from when doing an C<L> or C<-> command.
2206 C<$max> tells the debugger where the last line of the current file is. It's
2207 used to terminate loops most often.
2209 =head2 THE COMMAND LOOP
2211 Most of C<DB::DB> is actually a command parsing and dispatch loop. It comes
2218 The outer part of the loop, starting at the C<CMD> label. This loop
2219 reads a command and then executes it.
2223 The inner part of the loop, starting at the C<PIPE> label. This part
2224 is wholly contained inside the C<CMD> block and only executes a command.
2225 Used to handle commands running inside a pager.
2229 So why have two labels to restart the loop? Because sometimes, it's easier to
2230 have a command I<generate> another command and then re-execute the loop to do
2231 the new command. This is faster, but perhaps a bit more convoluted.
2235 # The big command dispatch loop. It keeps running until the
2236 # user yields up control again.
2238 # If we have a terminal for input, and we get something back
2239 # from readline(), keep on processing.
2243 # We have a terminal, or can get one ...
2244 ( $term || &setterm ),
2246 # ... and it belogs to this PID or we get one for this PID ...
2247 ( $term_pid == $$ or resetterm(1) ),
2249 # ... and we got a line of command input ...
2252 "$pidprompt $tid DB"
2255 . ( '>' x $level ) . " "
2262 # ... try to execute the input as debugger commands.
2264 # Don't stop running.
2267 # No signal is active.
2270 # Handle continued commands (ending with \):
2271 $cmd =~ s/\\$/\n/ && do {
2272 $cmd .= &readline(" cont: ");
2276 =head4 The null command
2278 A newline entered by itself means I<re-execute the last command>. We grab the
2279 command out of C<$laststep> (where it was recorded previously), and copy it
2280 back into C<$cmd> to be executed below. If there wasn't any previous command,
2281 we'll do nothing below (no command will match). If there was, we also save it
2282 in the command history and fall through to allow the command parsing to pick
2287 # Empty input means repeat the last command.
2288 $cmd =~ /^$/ && ( $cmd = $laststep );
2289 chomp($cmd); # get rid of the annoying extra newline
2290 push( @hist, $cmd ) if length($cmd) > 1;
2291 push( @truehist, $cmd );
2295 # This is a restart point for commands that didn't arrive
2296 # via direct user input. It allows us to 'redo PIPE' to
2297 # re-execute command processing without reading a new command.
2299 $cmd =~ s/^\s+//s; # trim annoying leading whitespace
2300 $cmd =~ s/\s+$//s; # trim annoying trailing whitespace
2301 ($i) = split( /\s+/, $cmd );
2303 =head3 COMMAND ALIASES
2305 The debugger can create aliases for commands (these are stored in the
2306 C<%alias> hash). Before a command is executed, the command loop looks it up
2307 in the alias hash and substitutes the contents of the alias for the command,
2308 completely replacing it.
2312 # See if there's an alias for the command, and set it up if so.
2315 # Squelch signal handling; we want to keep control here
2316 # if something goes loco during the alias eval.
2317 local $SIG{__DIE__};
2318 local $SIG{__WARN__};
2320 # This is a command, so we eval it in the DEBUGGER's
2321 # scope! Otherwise, we can't see the special debugger
2322 # variables, or get to the debugger's subs. (Well, we
2323 # _could_, but why make it even more complicated?)
2324 eval "\$cmd =~ $alias{$i}";
2327 print $OUT "Couldn't evaluate `$i' alias: $@";
2330 } ## end if ($alias{$i})
2332 =head3 MAIN-LINE COMMANDS
2334 All of these commands work up to and after the program being debugged has
2339 Quit the debugger. This entails setting the C<$fall_off_end> flag, so we don't
2340 try to execute further, cleaning any restart-related stuff out of the
2341 environment, and executing with the last value of C<$?>.
2345 $cmd =~ /^q$/ && do {
2353 Turn tracing on or off. Inverts the appropriate bit in C<$trace> (q.v.).
2357 $cmd =~ /^t$/ && do {
2360 print $OUT "Trace = "
2361 . ( ( $trace & 1 ) ? "on" : "off" ) . "\n";
2365 =head4 C<S> - list subroutines matching/not matching a pattern
2367 Walks through C<%sub>, checking to see whether or not to print the name.
2371 $cmd =~ /^S(\s+(!)?(.+))?$/ && do {
2373 $Srev = defined $2; # Reverse scan?
2374 $Spatt = $3; # The pattern (if any) to use.
2375 $Snocheck = !defined $1; # No args - print all subs.
2377 # Need to make these sane here.
2381 # Search through the debugger's magical hash of subs.
2382 # If $nocheck is true, just print the sub name.
2383 # Otherwise, check it against the pattern. We then use
2384 # the XOR trick to reverse the condition as required.
2385 foreach $subname ( sort( keys %sub ) ) {
2386 if ( $Snocheck or $Srev ^ ( $subname =~ /$Spatt/ ) ) {
2387 print $OUT $subname, "\n";
2393 =head4 C<X> - list variables in current package
2395 Since the C<V> command actually processes this, just change this to the
2396 appropriate C<V> command and fall through.
2400 $cmd =~ s/^X\b/V $package/;
2402 =head4 C<V> - list variables
2404 Uses C<dumpvar.pl> to dump out the current values for selected variables.
2408 # Bare V commands get the currently-being-debugged package
2410 $cmd =~ /^V$/ && do {
2411 $cmd = "V $package";
2414 # V - show variables in package.
2415 $cmd =~ /^V\b\s*(\S+)\s*(.*)/ && do {
2417 # Save the currently selected filehandle and
2418 # force output to debugger's filehandle (dumpvar
2419 # just does "print" for output).
2420 local ($savout) = select($OUT);
2422 # Grab package name and variables to dump.
2424 @vars = split( ' ', $2 );
2426 # If main::dumpvar isn't here, get it.
2427 do 'dumpvar.pl' || die $@ unless defined &main::dumpvar;
2428 if ( defined &main::dumpvar ) {
2430 # We got it. Turn off subroutine entry/exit messages
2431 # for the moment, along with return values.
2435 # must detect sigpipe failures - not catching
2436 # then will cause the debugger to die.
2440 defined $option{dumpDepth}
2441 ? $option{dumpDepth}
2442 : -1, # assume -1 unless specified
2447 # The die doesn't need to include the $@, because
2448 # it will automatically get propagated for us.
2450 die unless $@ =~ /dumpvar print failed/;
2452 } ## end if (defined &main::dumpvar)
2455 # Couldn't load dumpvar.
2456 print $OUT "dumpvar.pl not available.\n";
2459 # Restore the output filehandle, and go round again.
2464 =head4 C<x> - evaluate and print an expression
2466 Hands the expression off to C<DB::eval>, setting it up to print the value
2467 via C<dumpvar.pl> instead of just printing it directly.
2471 $cmd =~ s/^x\b/ / && do { # Remainder gets done by DB::eval()
2472 $onetimeDump = 'dump'; # main::dumpvar shows the output
2474 # handle special "x 3 blah" syntax XXX propagate
2475 # doc back to special variables.
2476 if ( $cmd =~ s/^\s*(\d+)(?=\s)/ / ) {
2477 $onetimedumpDepth = $1;
2481 =head4 C<m> - print methods
2483 Just uses C<DB::methods> to determine what methods are available.
2487 $cmd =~ s/^m\s+([\w:]+)\s*$/ / && do {
2492 # m expr - set up DB::eval to do the work
2493 $cmd =~ s/^m\b/ / && do { # Rest gets done by DB::eval()
2494 $onetimeDump = 'methods'; # method output gets used there
2497 =head4 C<f> - switch files
2501 $cmd =~ /^f\b\s*(.*)/ && do {
2505 # help for no arguments (old-style was return from sub).
2508 "The old f command is now the r command.\n"; # hint
2509 print $OUT "The new f command switches filenames.\n";
2511 } ## end if (!$file)
2513 # if not in magic file list, try a close match.
2514 if ( !defined $main::{ '_<' . $file } ) {
2515 if ( ($try) = grep( m#^_<.*$file#, keys %main:: ) ) {
2517 $try = substr( $try, 2 );
2518 print $OUT "Choosing $try matching `$file':\n";
2521 } ## end if (($try) = grep(m#^_<.*$file#...
2522 } ## end if (!defined $main::{ ...
2524 # If not successfully switched now, we failed.
2525 if ( !defined $main::{ '_<' . $file } ) {
2526 print $OUT "No file matching `$file' is loaded.\n";
2530 # We switched, so switch the debugger internals around.
2531 elsif ( $file ne $filename ) {
2532 *dbline = $main::{ '_<' . $file };
2537 } ## end elsif ($file ne $filename)
2539 # We didn't switch; say we didn't.
2541 print $OUT "Already in $file.\n";
2546 =head4 C<.> - return to last-executed line.
2548 We set C<$incr> to -1 to indicate that the debugger shouldn't move ahead,
2549 and then we look up the line in the magical C<%dbline> hash.
2554 $cmd =~ /^\.$/ && do {
2555 $incr = -1; # stay at current line
2557 # Reset everything to the old location.
2559 $filename = $filename_ini;
2560 *dbline = $main::{ '_<' . $filename };
2564 print_lineinfo($position);
2568 =head4 C<-> - back one window
2570 We change C<$start> to be one window back; if we go back past the first line,
2571 we set it to be the first line. We ser C<$incr> to put us back at the
2572 currently-executing line, and then put a C<l $start +> (list one window from
2573 C<$start>) in C<$cmd> to be executed later.
2577 # - - back a window.
2578 $cmd =~ /^-$/ && do {
2580 # back up by a window; go to 1 if back too far.
2581 $start -= $incr + $window + 1;
2582 $start = 1 if $start <= 0;
2583 $incr = $window - 1;
2585 # Generate and execute a "l +" command (handled below).
2586 $cmd = 'l ' . ($start) . '+';
2589 =head3 PRE-580 COMMANDS VS. NEW COMMANDS: C<a, A, b, B, h, l, L, M, o, O, P, v, w, W, E<lt>, E<lt>E<lt>, {, {{>
2591 In Perl 5.8.0, a realignment of the commands was done to fix up a number of
2592 problems, most notably that the default case of several commands destroying
2593 the user's work in setting watchpoints, actions, etc. We wanted, however, to
2594 retain the old commands for those who were used to using them or who preferred
2595 them. At this point, we check for the new commands and call C<cmd_wrapper> to
2596 deal with them instead of processing them in-line.
2600 # All of these commands were remapped in perl 5.8.0;
2601 # we send them off to the secondary dispatcher (see below).
2602 $cmd =~ /^([aAbBeEhilLMoOPvwW]\b|[<>\{]{1,2})\s*(.*)/so && do {
2603 &cmd_wrapper( $1, $2, $line );
2607 =head4 C<y> - List lexicals in higher scope
2609 Uses C<PadWalker> to find the lexicals supplied as arguments in a scope
2610 above the current one and then displays then using C<dumpvar.pl>.
2614 $cmd =~ /^y(?:\s+(\d*)\s*(.*))?$/ && do {
2616 # See if we've got the necessary support.
2617 eval { require PadWalker; PadWalker->VERSION(0.08) }
2620 ? "PadWalker module not found - please install\n"
2625 # Load up dumpvar if we don't have it. If we can, that is.
2626 do 'dumpvar.pl' || die $@ unless defined &main::dumpvar;
2627 defined &main::dumpvar
2628 or print $OUT "dumpvar.pl not available.\n"
2631 # Got all the modules we need. Find them and print them.
2632 my @vars = split( ' ', $2 || '' );
2635 my $h = eval { PadWalker::peek_my( ( $1 || 0 ) + 1 ) };
2637 # Oops. Can't find it.
2638 $@ and $@ =~ s/ at .*//, &warn($@), next CMD;
2640 # Show the desired vars with dumplex().
2641 my $savout = select($OUT);
2643 # Have dumplex dump the lexicals.
2644 dumpvar::dumplex( $_, $h->{$_},
2645 defined $option{dumpDepth} ? $option{dumpDepth} : -1,
2652 =head3 COMMANDS NOT WORKING AFTER PROGRAM ENDS
2654 All of the commands below this point don't work after the program being
2655 debugged has ended. All of them check to see if the program has ended; this
2656 allows the commands to be relocated without worrying about a 'line of
2657 demarcation' above which commands can be entered anytime, and below which
2660 =head4 C<n> - single step, but don't trace down into subs
2662 Done by setting C<$single> to 2, which forces subs to execute straight through
2663 when entered (see C<DB::sub>). We also save the C<n> command in C<$laststep>,
2664 so a null command knows what to re-execute.
2669 $cmd =~ /^n$/ && do {
2670 end_report(), next CMD if $finished and $level <= 1;
2672 # Single step, but don't enter subs.
2675 # Save for empty command (repeat last).
2680 =head4 C<s> - single-step, entering subs
2682 Sets C<$single> to 1, which causes C<DB::sub> to continue tracing inside
2683 subs. Also saves C<s> as C<$lastcmd>.
2688 $cmd =~ /^s$/ && do {
2690 # Get out and restart the command loop if program
2692 end_report(), next CMD if $finished and $level <= 1;
2694 # Single step should enter subs.
2697 # Save for empty command (repeat last).
2702 =head4 C<c> - run continuously, setting an optional breakpoint
2704 Most of the code for this command is taken up with locating the optional
2705 breakpoint, which is either a subroutine name or a line number. We set
2706 the appropriate one-time-break in C<@dbline> and then turn off single-stepping
2707 in this and all call levels above this one.
2711 # c - start continuous execution.
2712 $cmd =~ /^c\b\s*([\w:]*)\s*$/ && do {
2714 # Hey, show's over. The debugged program finished
2715 # executing already.
2716 end_report(), next CMD if $finished and $level <= 1;
2718 # Capture the place to put a one-time break.
2721 # Probably not needed, since we finish an interactive
2722 # sub-session anyway...
2723 # local $filename = $filename;
2724 # local *dbline = *dbline; # XXX Would this work?!
2726 # The above question wonders if localizing the alias
2727 # to the magic array works or not. Since it's commented
2728 # out, we'll just leave that to speculation for now.
2730 # If the "subname" isn't all digits, we'll assume it
2731 # is a subroutine name, and try to find it.
2732 if ( $subname =~ /\D/ ) { # subroutine name
2733 # Qualify it to the current package unless it's
2734 # already qualified.
2735 $subname = $package . "::" . $subname
2736 unless $subname =~ /::/;
2738 # find_sub will return "file:line_number" corresponding
2739 # to where the subroutine is defined; we call find_sub,
2740 # break up the return value, and assign it in one
2742 ( $file, $i ) = ( find_sub($subname) =~ /^(.*):(.*)$/ );
2744 # Force the line number to be numeric.
2747 # If we got a line number, we found the sub.
2750 # Switch all the debugger's internals around so
2751 # we're actually working with that file.
2753 *dbline = $main::{ '_<' . $filename };
2755 # Mark that there's a breakpoint in this file.
2756 $had_breakpoints{$filename} |= 1;
2758 # Scan forward to the first executable line
2759 # after the 'sub whatever' line.
2761 ++$i while $dbline[$i] == 0 && $i < $max;
2764 # We didn't find a sub by that name.
2766 print $OUT "Subroutine $subname not found.\n";
2769 } ## end if ($subname =~ /\D/)
2771 # At this point, either the subname was all digits (an
2772 # absolute line-break request) or we've scanned through
2773 # the code following the definition of the sub, looking
2774 # for an executable, which we may or may not have found.
2776 # If $i (which we set $subname from) is non-zero, we
2777 # got a request to break at some line somewhere. On
2778 # one hand, if there wasn't any real subroutine name
2779 # involved, this will be a request to break in the current
2780 # file at the specified line, so we have to check to make
2781 # sure that the line specified really is breakable.
2783 # On the other hand, if there was a subname supplied, the
2784 # preceding block has moved us to the proper file and
2785 # location within that file, and then scanned forward
2786 # looking for the next executable line. We have to make
2787 # sure that one was found.
2789 # On the gripping hand, we can't do anything unless the
2790 # current value of $i points to a valid breakable line.
2795 if ( $dbline[$i] == 0 ) {
2796 print $OUT "Line $i not breakable.\n";
2800 # Yes. Set up the one-time-break sigil.
2801 $dbline{$i} =~ s/($|\0)/;9$1/; # add one-time-only b.p.
2804 # Turn off stack tracing from here up.
2805 for ( $i = 0 ; $i <= $stack_depth ; ) {
2806 $stack[ $i++ ] &= ~1;
2811 =head4 C<r> - return from a subroutine
2813 For C<r> to work properly, the debugger has to stop execution again
2814 immediately after the return is executed. This is done by forcing
2815 single-stepping to be on in the call level above the current one. If
2816 we are printing return values when a C<r> is executed, set C<$doret>
2817 appropriately, and force us out of the command loop.
2821 # r - return from the current subroutine.
2822 $cmd =~ /^r$/ && do {
2824 # Can't do anythign if the program's over.
2825 end_report(), next CMD if $finished and $level <= 1;
2827 # Turn on stack trace.
2828 $stack[$stack_depth] |= 1;
2830 # Print return value unless the stack is empty.
2831 $doret = $option{PrintRet} ? $stack_depth - 1 : -2;
2835 =head4 C<T> - stack trace
2837 Just calls C<DB::print_trace>.
2841 $cmd =~ /^T$/ && do {
2842 print_trace( $OUT, 1 ); # skip DB
2846 =head4 C<w> - List window around current line.
2848 Just calls C<DB::cmd_w>.
2852 $cmd =~ /^w\b\s*(.*)/s && do { &cmd_w( 'w', $1 ); next CMD; };
2854 =head4 C<W> - watch-expression processing.
2856 Just calls C<DB::cmd_W>.
2860 $cmd =~ /^W\b\s*(.*)/s && do { &cmd_W( 'W', $1 ); next CMD; };
2862 =head4 C</> - search forward for a string in the source
2864 We take the argument and treat it as a pattern. If it turns out to be a
2865 bad one, we return the error we got from trying to C<eval> it and exit.
2866 If not, we create some code to do the search and C<eval> it so it can't
2871 $cmd =~ /^\/(.*)$/ && do {
2873 # The pattern as a string.
2876 # Remove the final slash.
2877 $inpat =~ s:([^\\])/$:$1:;
2879 # If the pattern isn't null ...
2880 if ( $inpat ne "" ) {
2882 # Turn of warn and die procesing for a bit.
2883 local $SIG{__DIE__};
2884 local $SIG{__WARN__};
2886 # Create the pattern.
2887 eval '$inpat =~ m' . "\a$inpat\a";
2890 # Oops. Bad pattern. No biscuit.
2891 # Print the eval error and go back for more
2897 } ## end if ($inpat ne "")
2899 # Set up to stop on wrap-around.
2902 # Don't move off the current line.
2905 # Done in eval so nothing breaks if the pattern
2906 # does something weird.
2909 # Move ahead one line.
2912 # Wrap if we pass the last line.
2913 $start = 1 if ($start > $max);
2915 # Stop if we have gotten back to this line again,
2916 last if ($start == $end);
2918 # A hit! (Note, though, that we are doing
2919 # case-insensitive matching. Maybe a qr//
2920 # expression would be better, so the user could
2921 # do case-sensitive matching if desired.
2922 if ($dbline[$start] =~ m' . "\a$pat\a" . 'i) {
2923 if ($slave_editor) {
2924 # Handle proper escaping in the slave.
2925 print $OUT "\032\032$filename:$start:0\n";
2928 # Just print the line normally.
2929 print $OUT "$start:\t",$dbline[$start],"\n";
2931 # And quit since we found something.
2936 # If we wrapped, there never was a match.
2937 print $OUT "/$pat/: not found\n" if ( $start == $end );
2941 =head4 C<?> - search backward for a string in the source
2943 Same as for C</>, except the loop runs backwards.
2947 # ? - backward pattern search.
2948 $cmd =~ /^\?(.*)$/ && do {
2950 # Get the pattern, remove trailing question mark.
2952 $inpat =~ s:([^\\])\?$:$1:;
2954 # If we've got one ...
2955 if ( $inpat ne "" ) {
2957 # Turn off die & warn handlers.
2958 local $SIG{__DIE__};
2959 local $SIG{__WARN__};
2960 eval '$inpat =~ m' . "\a$inpat\a";
2964 # Ouch. Not good. Print the error.
2969 } ## end if ($inpat ne "")
2971 # Where we are now is where to stop after wraparound.
2974 # Don't move away from this line.
2977 # Search inside the eval to prevent pattern badness
2984 # Wrap if we pass the first line.
2986 $start = $max if ($start <= 0);
2988 # Quit if we get back where we started,
2989 last if ($start == $end);
2992 if ($dbline[$start] =~ m' . "\a$pat\a" . 'i) {
2993 if ($slave_editor) {
2994 # Yep, follow slave editor requirements.
2995 print $OUT "\032\032$filename:$start:0\n";
2998 # Yep, just print normally.
2999 print $OUT "$start:\t",$dbline[$start],"\n";
3007 # Say we failed if the loop never found anything,
3008 print $OUT "?$pat?: not found\n" if ( $start == $end );
3012 =head4 C<$rc> - Recall command
3014 Manages the commands in C<@hist> (which is created if C<Term::ReadLine> reports
3015 that the terminal supports history). It find the the command required, puts it
3016 into C<$cmd>, and redoes the loop to execute it.
3020 # $rc - recall command.
3021 $cmd =~ /^$rc+\s*(-)?(\d+)?$/ && do {
3023 # No arguments, take one thing off history.
3024 pop(@hist) if length($cmd) > 1;
3026 # Relative (- found)?
3027 # Y - index back from most recent (by 1 if bare minus)
3028 # N - go to that particular command slot or the last
3029 # thing if nothing following.
3030 $i = $1 ? ( $#hist - ( $2 || 1 ) ) : ( $2 || $#hist );
3032 # Pick out the command desired.
3035 # Print the command to be executed and restart the loop
3036 # with that command in the buffer.
3037 print $OUT $cmd, "\n";
3041 =head4 C<$sh$sh> - C<system()> command
3043 Calls the C<DB::system()> to handle the command. This keeps the C<STDIN> and
3044 C<STDOUT> from getting messed up.
3048 # $sh$sh - run a shell command (if it's all ASCII).
3049 # Can't run shell commands with Unicode in the debugger, hmm.
3050 $cmd =~ /^$sh$sh\s*([\x00-\xff]*)/ && do {
3057 =head4 C<$rc I<pattern> $rc> - Search command history
3059 Another command to manipulate C<@hist>: this one searches it with a pattern.
3060 If a command is found, it is placed in C<$cmd> and executed via C<redo>.
3064 # $rc pattern $rc - find a command in the history.
3065 $cmd =~ /^$rc([^$rc].*)$/ && do {
3067 # Create the pattern to use.
3070 # Toss off last entry if length is >1 (and it always is).
3071 pop(@hist) if length($cmd) > 1;
3073 # Look backward through the history.
3074 for ( $i = $#hist ; $i ; --$i ) {
3076 # Stop if we find it.
3077 last if $hist[$i] =~ /$pat/;
3083 print $OUT "No such command!\n\n";
3087 # Found it. Put it in the buffer, print it, and process it.
3089 print $OUT $cmd, "\n";
3093 =head4 C<$sh> - Invoke a shell
3095 Uses C<DB::system> to invoke a shell.
3099 # $sh - start a shell.
3100 $cmd =~ /^$sh$/ && do {
3102 # Run the user's shell. If none defined, run Bourne.
3103 # We resume execution when the shell terminates.
3104 &system( $ENV{SHELL} || "/bin/sh" );
3108 =head4 C<$sh I<command>> - Force execution of a command in a shell
3110 Like the above, but the command is passed to the shell. Again, we use
3111 C<DB::system> to avoid problems with C<STDIN> and C<STDOUT>.
3115 # $sh command - start a shell and run a command in it.
3116 $cmd =~ /^$sh\s*([\x00-\xff]*)/ && do {
3118 # XXX: using csh or tcsh destroys sigint retvals!
3119 #&system($1); # use this instead
3121 # use the user's shell, or Bourne if none defined.
3122 &system( $ENV{SHELL} || "/bin/sh", "-c", $1 );
3126 =head4 C<H> - display commands in history
3128 Prints the contents of C<@hist> (if any).
3132 $cmd =~ /^H\b\s*\*/ && do {
3133 @hist = @truehist = ();
3134 print $OUT "History cleansed\n";
3138 $cmd =~ /^H\b\s*(-(\d+))?/ && do {
3140 # Anything other than negative numbers is ignored by
3141 # the (incorrect) pattern, so this test does nothing.
3142 $end = $2 ? ( $#hist - $2 ) : 0;
3144 # Set to the minimum if less than zero.
3145 $hist = 0 if $hist < 0;
3147 # Start at the end of the array.
3148 # Stay in while we're still above the ending value.
3149 # Tick back by one each time around the loop.
3150 for ( $i = $#hist ; $i > $end ; $i-- ) {
3152 # Print the command unless it has no arguments.
3153 print $OUT "$i: ", $hist[$i], "\n"
3154 unless $hist[$i] =~ /^.?$/;
3159 =head4 C<man, doc, perldoc> - look up documentation
3161 Just calls C<runman()> to print the appropriate document.
3165 # man, perldoc, doc - show manual pages.
3166 $cmd =~ /^(?:man|(?:perl)?doc)\b(?:\s+([^(]*))?$/ && do {
3173 Builds a C<print EXPR> expression in the C<$cmd>; this will get executed at
3174 the bottom of the loop.
3178 # p - print (no args): print $_.
3179 $cmd =~ s/^p$/print {\$DB::OUT} \$_/;
3181 # p - print the given expression.
3182 $cmd =~ s/^p\b/print {\$DB::OUT} /;
3184 =head4 C<=> - define command alias
3186 Manipulates C<%alias> to add or list command aliases.
3190 # = - set up a command alias.
3191 $cmd =~ s/^=\s*// && do {
3193 if ( length $cmd == 0 ) {
3195 # No args, get current aliases.
3196 @keys = sort keys %alias;
3198 elsif ( my ( $k, $v ) = ( $cmd =~ /^(\S+)\s+(\S.*)/ ) ) {
3200 # Creating a new alias. $k is alias name, $v is
3203 # can't use $_ or kill //g state
3204 for my $x ( $k, $v ) {
3206 # Escape "alarm" characters.
3210 # Substitute key for value, using alarm chars
3211 # as separators (which is why we escaped them in
3213 $alias{$k} = "s\a$k\a$v\a";
3215 # Turn off standard warn and die behavior.
3216 local $SIG{__DIE__};
3217 local $SIG{__WARN__};
3220 unless ( eval "sub { s\a$k\a$v\a }; 1" ) {
3222 # Nope. Bad alias. Say so and get out.
3223 print $OUT "Can't alias $k to $v: $@\n";
3228 # We'll only list the new one.
3230 } ## end elsif (my ($k, $v) = ($cmd...
3232 # The argument is the alias to list.
3240 # Messy metaquoting: Trim the substiution code off.
3241 # We use control-G as the delimiter because it's not
3242 # likely to appear in the alias.
3243 if ( ( my $v = $alias{$k} ) =~ s
\as\a$k\a(.*)\a$
\a1
\a ) {
3246 print $OUT "$k\t= $1\n";
3248 elsif ( defined $alias{$k} ) {
3250 # Couldn't trim it off; just print the alias code.
3251 print $OUT "$k\t$alias{$k}\n";
3256 print "No alias for $k\n";
3258 } ## end for my $k (@keys)
3262 =head4 C<source> - read commands from a file.
3264 Opens a lexical filehandle and stacks it on C<@cmdfhs>; C<DB::readline> will
3269 # source - read commands from a file (or pipe!) and execute.
3270 $cmd =~ /^source\s+(.*\S)/ && do {
3271 if ( open my $fh, $1 ) {
3273 # Opened OK; stick it in the list of file handles.
3279 &warn("Can't execute `$1': $!\n");
3284 =head4 C<save> - send current history to a file
3286 Takes the complete history, (not the shrunken version you see with C<H>),
3287 and saves it to the given filename, so it can be replayed using C<source>.
3289 Note that all C<^(save|source)>'s are commented out with a view to minimise recursion.
3293 # save source - write commands to a file for later use
3294 $cmd =~ /^save\s*(.*)$/ && do {
3295 my $file = $1 || '.perl5dbrc'; # default?
3296 if ( open my $fh, "> $file" ) {
3298 # chomp to remove extraneous newlines from source'd files
3299 chomp( my @truelist =
3300 map { m/^\s*(save|source)/ ? "#$_" : $_ }
3302 print $fh join( "\n", @truelist );
3303 print "commands saved in $file\n";
3306 &warn("Can't save debugger commands in '$1': $!\n");
3311 =head4 C<R> - restart
3313 Restart the debugger session.
3315 =head4 C<rerun> - rerun the current session
3317 Return to any given position in the B<true>-history list
3321 # R - restart execution.
3322 # rerun - controlled restart execution.
3323 $cmd =~ /^(R|rerun\s*(.*))$/ && do {
3324 my @args = ($1 eq 'R' ? restart() : rerun($2));
3326 # Close all non-system fds for a clean restart. A more
3327 # correct method would be to close all fds that were not
3328 # open when the process started, but this seems to be
3329 # hard. See "debugger 'R'estart and open database
3330 # connections" on p5p.
3332 my $max_fd = 1024; # default if POSIX can't be loaded
3333 if (eval { require POSIX }) {
3334 $max_fd = POSIX::sysconf(POSIX::_SC_OPEN_MAX());
3337 if (defined $max_fd) {
3338 foreach ($^F+1 .. $max_fd-1) {
3339 next unless open FD_TO_CLOSE, "<&=$_";
3344 # And run Perl again. We use exec() to keep the
3345 # PID stable (and that way $ini_pids is still valid).
3346 exec(@args) || print $OUT "exec failed: $!\n";
3351 =head4 C<|, ||> - pipe output through the pager.
3353 For C<|>, we save C<OUT> (the debugger's output filehandle) and C<STDOUT>
3354 (the program's standard output). For C<||>, we only save C<OUT>. We open a
3355 pipe to the pager (restoring the output filehandles if this fails). If this
3356 is the C<|> command, we also set up a C<SIGPIPE> handler which will simply
3357 set C<$signal>, sending us back into the debugger.
3359 We then trim off the pipe symbols and C<redo> the command loop at the
3360 C<PIPE> label, causing us to evaluate the command in C<$cmd> without
3365 # || - run command in the pager, with output to DB::OUT.
3366 $cmd =~ /^\|\|?\s*[^|]/ && do {
3367 if ( $pager =~ /^\|/ ) {
3369 # Default pager is into a pipe. Redirect I/O.
3370 open( SAVEOUT, ">&STDOUT" )
3371 || &warn("Can't save STDOUT");
3372 open( STDOUT, ">&OUT" )
3373 || &warn("Can't redirect STDOUT");
3374 } ## end if ($pager =~ /^\|/)
3377 # Not into a pipe. STDOUT is safe.
3378 open( SAVEOUT, ">&OUT" ) || &warn("Can't save DB::OUT");
3381 # Fix up environment to record we have less if so.
3384 unless ( $piped = open( OUT, $pager ) ) {
3386 # Couldn't open pipe to pager.
3387 &warn("Can't pipe output to `$pager'");
3388 if ( $pager =~ /^\|/ ) {
3390 # Redirect I/O back again.
3391 open( OUT, ">&STDOUT" ) # XXX: lost message
3392 || &warn("Can't restore DB::OUT");
3393 open( STDOUT, ">&SAVEOUT" )
3394 || &warn("Can't restore STDOUT");
3396 } ## end if ($pager =~ /^\|/)
3399 # Redirect I/O. STDOUT already safe.
3400 open( OUT, ">&STDOUT" ) # XXX: lost message
3401 || &warn("Can't restore DB::OUT");
3404 } ## end unless ($piped = open(OUT,...
3406 # Set up broken-pipe handler if necessary.
3407 $SIG{PIPE} = \&DB::catch
3409 && ( "" eq $SIG{PIPE} || "DEFAULT" eq $SIG{PIPE} );
3411 # Save current filehandle, unbuffer out, and put it back.
3412 $selected = select(OUT);
3415 # Don't put it back if pager was a pipe.
3416 select($selected), $selected = "" unless $cmd =~ /^\|\|/;
3418 # Trim off the pipe symbols and run the command now.
3419 $cmd =~ s/^\|+\s*//;
3423 =head3 END OF COMMAND PARSING
3425 Anything left in C<$cmd> at this point is a Perl expression that we want to
3426 evaluate. We'll always evaluate in the user's context, and fully qualify
3427 any variables we might want to address in the C<DB> package.
3431 # t - turn trace on.
3432 $cmd =~ s/^t\s/\$DB::trace |= 1;\n/;
3434 # s - single-step. Remember the last command was 's'.
3435 $cmd =~ s/^s\s/\$DB::single = 1;\n/ && do { $laststep = 's' };
3437 # n - single-step, but not into subs. Remember last command
3439 $cmd =~ s/^n\s/\$DB::single = 2;\n/ && do { $laststep = 'n' };
3443 # Make sure the flag that says "the debugger's running" is
3444 # still on, to make sure we get control again.
3445 $evalarg = "\$^D = \$^D | \$DB::db_stop;\n$cmd";
3447 # Run *our* eval that executes in the caller's context.
3450 # Turn off the one-time-dump stuff now.
3452 $onetimeDump = undef;
3453 $onetimedumpDepth = undef;
3455 elsif ( $term_pid == $$ ) {
3456 eval { # May run under miniperl, when not available...
3461 # XXX If this is the master pid, print a newline.
3464 } ## end while (($term || &setterm...
3466 =head3 POST-COMMAND PROCESSING
3468 After each command, we check to see if the command output was piped anywhere.
3469 If so, we go through the necessary code to unhook the pipe and go back to
3470 our standard filehandles for input and output.
3476 # At the end of every command:
3479 # Unhook the pipe mechanism now.
3480 if ( $pager =~ /^\|/ ) {
3482 # No error from the child.
3485 # we cannot warn here: the handle is missing --tchrist
3486 close(OUT) || print SAVEOUT "\nCan't close DB::OUT\n";
3488 # most of the $? crud was coping with broken cshisms
3489 # $? is explicitly set to 0, so this never runs.
3491 print SAVEOUT "Pager `$pager' failed: ";
3493 print SAVEOUT "shell returned -1\n";
3496 print SAVEOUT ( $? & 127 )
3497 ? " (SIG#" . ( $? & 127 ) . ")"
3498 : "", ( $? & 128 ) ? " -- core dumped" : "", "\n";
3501 print SAVEOUT "status ", ( $? >> 8 ), "\n";
3505 # Reopen filehandle for our output (if we can) and
3506 # restore STDOUT (if we can).
3507 open( OUT, ">&STDOUT" ) || &warn("Can't restore DB::OUT");
3508 open( STDOUT, ">&SAVEOUT" )
3509 || &warn("Can't restore STDOUT");
3511 # Turn off pipe exception handler if necessary.
3512 $SIG{PIPE} = "DEFAULT" if $SIG{PIPE} eq \&DB::catch;
3514 # Will stop ignoring SIGPIPE if done like nohup(1)
3515 # does SIGINT but Perl doesn't give us a choice.
3516 } ## end if ($pager =~ /^\|/)
3519 # Non-piped "pager". Just restore STDOUT.
3520 open( OUT, ">&SAVEOUT" ) || &warn("Can't restore DB::OUT");
3523 # Close filehandle pager was using, restore the normal one
3526 select($selected), $selected = "" unless $selected eq "";
3530 } ## end if ($piped)
3533 =head3 COMMAND LOOP TERMINATION
3535 When commands have finished executing, we come here. If the user closed the
3536 input filehandle, we turn on C<$fall_off_end> to emulate a C<q> command. We
3537 evaluate any post-prompt items. We restore C<$@>, C<$!>, C<$^E>, C<$,>, C<$/>,
3538 C<$\>, and C<$^W>, and return a null list as expected by the Perl interpreter.
3539 The interpreter will then execute the next line and then return control to us
3544 # No more commands? Quit.
3545 $fall_off_end = 1 unless defined $cmd; # Emulate `q' on EOF
3547 # Evaluate post-prompt commands.
3548 foreach $evalarg (@$post) {
3551 } # if ($single || $signal)
3553 # Put the user's globals back where you found them.
3554 ( $@, $!, $^E, $,, $/, $\, $^W ) = @saved;
3558 # The following code may be executed now:
3563 C<sub> is called whenever a subroutine call happens in the program being
3564 debugged. The variable C<$DB::sub> contains the name of the subroutine
3567 The core function of this subroutine is to actually call the sub in the proper
3568 context, capturing its output. This of course causes C<DB::DB> to get called
3569 again, repeating until the subroutine ends and returns control to C<DB::sub>
3570 again. Once control returns, C<DB::sub> figures out whether or not to dump the
3571 return value, and returns its captured copy of the return value as its own
3572 return value. The value then feeds back into the program being debugged as if
3573 C<DB::sub> hadn't been there at all.
3575 C<sub> does all the work of printing the subroutine entry and exit messages
3576 enabled by setting C<$frame>. It notes what sub the autoloader got called for,
3577 and also prints the return value if needed (for the C<r> command and if
3578 the 16 bit is set in C<$frame>).
3580 It also tracks the subroutine call depth by saving the current setting of
3581 C<$single> in the C<@stack> package global; if this exceeds the value in
3582 C<$deep>, C<sub> automatically turns on printing of the current depth by
3583 setting the C<4> bit in C<$single>. In any case, it keeps the current setting
3584 of stop/don't stop on entry to subs set as it currently is set.
3586 =head3 C<caller()> support
3588 If C<caller()> is called from the package C<DB>, it provides some
3589 additional data, in the following order:
3595 The package name the sub was in
3597 =item * C<$filename>
3599 The filename it was defined in
3603 The line number it was defined on
3605 =item * C<$subroutine>
3607 The subroutine name; C<(eval)> if an C<eval>().
3611 1 if it has arguments, 0 if not
3613 =item * C<$wantarray>
3615 1 if array context, 0 if scalar context
3617 =item * C<$evaltext>
3619 The C<eval>() text, if any (undefined for C<eval BLOCK>)
3621 =item * C<$is_require>
3623 frame was created by a C<use> or C<require> statement
3627 pragma information; subject to change between versions
3631 pragma information; subject to change between versions
3633 =item * C<@DB::args>
3635 arguments with which the subroutine was invoked
3642 # Do not use a regex in this subroutine -> results in corrupted memory
3643 # See: [perl #66110]
3645 # lock ourselves under threads
3648 # Whether or not the autoloader was running, a scalar to put the
3649 # sub's return value in (if needed), and an array to put the sub's
3650 # return value in (if needed).
3651 my ( $al, $ret, @ret ) = "";
3652 if ($sub eq 'threads::new' && $ENV{PERL5DB_THREADED}) {
3653 print "creating new thread\n";
3656 # If the last ten characters are '::AUTOLOAD', note we've traced
3657 # into AUTOLOAD for $sub.
3658 if ( length($sub) > 10 && substr( $sub, -10, 10 ) eq '::AUTOLOAD' ) {
3659 $al = " for $$sub" if defined $$sub;
3662 # We stack the stack pointer and then increment it to protect us
3663 # from a situation that might unwind a whole bunch of call frames
3664 # at once. Localizing the stack pointer means that it will automatically
3665 # unwind the same amount when multiple stack frames are unwound.
3666 local $stack_depth = $stack_depth + 1; # Protect from non-local exits
3669 $#stack = $stack_depth;
3671 # Save current single-step setting.
3672 $stack[-1] = $single;
3674 # Turn off all flags except single-stepping.
3677 # If we've gotten really deeply recursed, turn on the flag that will
3678 # make us stop with the 'deep recursion' message.
3679 $single |= 4 if $stack_depth == $deep;
3681 # If frame messages are on ...
3683 $frame & 4 # Extended frame entry message
3685 print_lineinfo( ' ' x ( $stack_depth - 1 ), "in " ),
3687 # Why -1? But it works! :-(
3688 # Because print_trace will call add 1 to it and then call
3689 # dump_trace; this results in our skipping -1+1 = 0 stack frames
3691 print_trace( $LINEINFO, -1, 1, 1, "$sub$al" )
3693 : print_lineinfo( ' ' x ( $stack_depth - 1 ), "entering $sub$al\n" )
3695 # standard frame entry message
3699 # Determine the sub's return type,and capture approppriately.
3702 # Called in array context. call sub and capture output.
3703 # DB::DB will recursively get control again if appropriate; we'll come
3704 # back here when the sub is finished.
3707 # Pop the single-step value back off the stack.
3708 $single |= $stack[ $stack_depth-- ];
3710 # Check for exit trace messages...
3712 $frame & 4 # Extended exit message
3714 print_lineinfo( ' ' x $stack_depth, "out " ),
3715 print_trace( $LINEINFO, -1, 1, 1, "$sub$al" )
3717 : print_lineinfo( ' ' x $stack_depth, "exited $sub$al\n" )
3719 # Standard exit message
3723 # Print the return info if we need to.
3724 if ( $doret eq $stack_depth or $frame & 16 ) {
3726 # Turn off output record separator.
3728 my $fh = ( $doret eq $stack_depth ? $OUT : $LINEINFO );
3730 # Indent if we're printing because of $frame tracing.
3731 print $fh ' ' x $stack_depth if $frame & 16;
3733 # Print the return value.
3734 print $fh "list context return from $sub:\n";
3735 dumpit( $fh, \@ret );
3737 # And don't print it again.
3739 } ## end if ($doret eq $stack_depth...
3740 # And we have to return the return value now.
3742 } ## end if (wantarray)
3746 if ( defined wantarray ) {
3748 # Save the value if it's wanted at all.
3753 # Void return, explicitly.
3758 # Pop the single-step value off the stack.
3759 $single |= $stack[ $stack_depth-- ];
3761 # If we're doing exit messages...
3763 $frame & 4 # Extended messsages
3765 print_lineinfo( ' ' x $stack_depth, "out " ),
3766 print_trace( $LINEINFO, -1, 1, 1, "$sub$al" )
3768 : print_lineinfo( ' ' x $stack_depth, "exited $sub$al\n" )
3774 # If we are supposed to show the return value... same as before.
3775 if ( $doret eq $stack_depth or $frame & 16 and defined wantarray ) {
3777 my $fh = ( $doret eq $stack_depth ? $OUT : $LINEINFO );
3778 print $fh ( ' ' x $stack_depth ) if $frame & 16;
3781 ? "scalar context return from $sub: "
3782 : "void context return from $sub\n"
3784 dumpit( $fh, $ret ) if defined wantarray;
3786 } ## end if ($doret eq $stack_depth...
3788 # Return the appropriate scalar value.
3790 } ## end else [ if (wantarray)
3795 # lock ourselves under threads
3798 # Whether or not the autoloader was running, a scalar to put the
3799 # sub's return value in (if needed), and an array to put the sub's
3800 # return value in (if needed).
3801 my ( $al, $ret, @ret ) = "";
3802 if ($sub =~ /^threads::new$/ && $ENV{PERL5DB_THREADED}) {
3803 print "creating new thread\n";
3806 # If the last ten characters are C'::AUTOLOAD', note we've traced
3807 # into AUTOLOAD for $sub.
3808 if ( length($sub) > 10 && substr( $sub, -10, 10 ) eq '::AUTOLOAD' ) {
3812 # We stack the stack pointer and then increment it to protect us
3813 # from a situation that might unwind a whole bunch of call frames
3814 # at once. Localizing the stack pointer means that it will automatically
3815 # unwind the same amount when multiple stack frames are unwound.
3816 local $stack_depth = $stack_depth + 1; # Protect from non-local exits
3819 $#stack = $stack_depth;
3821 # Save current single-step setting.
3822 $stack[-1] = $single;
3824 # Turn off all flags except single-stepping.
3827 # If we've gotten really deeply recursed, turn on the flag that will
3828 # make us stop with the 'deep recursion' message.
3829 $single |= 4 if $stack_depth == $deep;
3831 # If frame messages are on ...
3833 $frame & 4 # Extended frame entry message
3835 print_lineinfo( ' ' x ( $stack_depth - 1 ), "in " ),
3837 # Why -1? But it works! :-(
3838 # Because print_trace will call add 1 to it and then call
3839 # dump_trace; this results in our skipping -1+1 = 0 stack frames
3841 print_trace( $LINEINFO, -1, 1, 1, "$sub$al" )
3843 : print_lineinfo( ' ' x ( $stack_depth - 1 ), "entering $sub$al\n" )
3845 # standard frame entry message
3849 # Pop the single-step value back off the stack.
3850 $single |= $stack[ $stack_depth-- ];
3852 # call the original lvalue sub.
3856 =head1 EXTENDED COMMAND HANDLING AND THE COMMAND API
3858 In Perl 5.8.0, there was a major realignment of the commands and what they did,
3859 Most of the changes were to systematize the command structure and to eliminate
3860 commands that threw away user input without checking.
3862 The following sections describe the code added to make it easy to support
3863 multiple command sets with conflicting command names. This section is a start
3864 at unifying all command processing to make it simpler to develop commands.
3866 Note that all the cmd_[a-zA-Z] subroutines require the command name, a line
3867 number, and C<$dbline> (the current line) as arguments.
3869 Support functions in this section which have multiple modes of failure C<die>
3870 on error; the rest simply return a false value.
3872 The user-interface functions (all of the C<cmd_*> functions) just output
3877 The C<%set> hash defines the mapping from command letter to subroutine
3880 C<%set> is a two-level hash, indexed by set name and then by command name.
3881 Note that trying to set the CommandSet to C<foobar> simply results in the
3882 5.8.0 command set being used, since there's no top-level entry for C<foobar>.
3891 'A' => 'pre580_null',
3893 'B' => 'pre580_null',
3894 'd' => 'pre580_null',
3897 'M' => 'pre580_null',
3899 'o' => 'pre580_null',
3905 '<' => 'pre590_prepost',
3906 '<<' => 'pre590_prepost',
3907 '>' => 'pre590_prepost',
3908 '>>' => 'pre590_prepost',
3909 '{' => 'pre590_prepost',
3910 '{{' => 'pre590_prepost',
3914 =head2 C<cmd_wrapper()> (API)
3916 C<cmd_wrapper()> allows the debugger to switch command sets
3917 depending on the value of the C<CommandSet> option.
3919 It tries to look up the command in the C<%set> package-level I<lexical>
3920 (which means external entities can't fiddle with it) and create the name of
3921 the sub to call based on the value found in the hash (if it's there). I<All>
3922 of the commands to be handled in a set have to be added to C<%set>; if they
3923 aren't found, the 5.8.0 equivalent is called (if there is one).
3925 This code uses symbolic references.
3932 my $dblineno = shift;
3934 # Assemble the command subroutine's name by looking up the
3935 # command set and command name in %set. If we can't find it,
3936 # default to the older version of the command.
3938 . ( $set{$CommandSet}{$cmd}
3939 || ( $cmd =~ /^[<>{]+/o ? 'prepost' : $cmd ) );
3941 # Call the command subroutine, call it by name.
3942 return &$call( $cmd, $line, $dblineno );
3943 } ## end sub cmd_wrapper
3945 =head3 C<cmd_a> (command)
3947 The C<a> command handles pre-execution actions. These are associated with a
3948 particular line, so they're stored in C<%dbline>. We default to the current
3949 line if none is specified.
3955 my $line = shift || ''; # [.|line] expr
3958 # If it's dot (here), or not all digits, use the current line.
3959 $line =~ s/^(\.|(?:[^\d]))/$dbline/;
3961 # Should be a line number followed by an expression.
3962 if ( $line =~ /^\s*(\d*)\s*(\S.+)/ ) {
3963 my ( $lineno, $expr ) = ( $1, $2 );
3965 # If we have an expression ...
3966 if ( length $expr ) {
3968 # ... but the line isn't breakable, complain.
3969 if ( $dbline[$lineno] == 0 ) {
3971 "Line $lineno($dbline[$lineno]) does not have an action?\n";
3975 # It's executable. Record that the line has an action.
3976 $had_breakpoints{$filename} |= 2;
3978 # Remove any action, temp breakpoint, etc.
3979 $dbline{$lineno} =~ s/\0[^\0]*//;
3981 # Add the action to the line.
3982 $dbline{$lineno} .= "\0" . action($expr);
3984 } ## end if (length $expr)
3985 } ## end if ($line =~ /^\s*(\d*)\s*(\S.+)/)
3990 "Adding an action requires an optional lineno and an expression\n"
3995 =head3 C<cmd_A> (command)
3997 Delete actions. Similar to above, except the delete code is in a separate
3998 subroutine, C<delete_action>.
4004 my $line = shift || '';
4008 $line =~ s/^\./$dbline/;
4010 # Call delete_action with a null param to delete them all.
4011 # The '1' forces the eval to be true. It'll be false only
4012 # if delete_action blows up for some reason, in which case
4013 # we print $@ and get out.
4014 if ( $line eq '*' ) {
4015 eval { &delete_action(); 1 } or print $OUT $@ and return;
4018 # There's a real line number. Pass it to delete_action.
4019 # Error trapping is as above.
4020 elsif ( $line =~ /^(\S.*)/ ) {
4021 eval { &delete_action($1); 1 } or print $OUT $@ and return;
4024 # Swing and a miss. Bad syntax.
4027 "Deleting an action requires a line number, or '*' for all\n" ; # hint
4031 =head3 C<delete_action> (API)
4033 C<delete_action> accepts either a line number or C<undef>. If a line number
4034 is specified, we check for the line being executable (if it's not, it
4035 couldn't have had an action). If it is, we just take the action off (this
4036 will get any kind of an action, including breakpoints).
4042 if ( defined($i) ) {
4045 die "Line $i has no action .\n" if $dbline[$i] == 0;
4047 # Nuke whatever's there.
4048 $dbline{$i} =~ s/\0[^\0]*//; # \^a
4049 delete $dbline{$i} if $dbline{$i} eq '';
4052 print $OUT "Deleting all actions...\n";
4053 for my $file ( keys %had_breakpoints ) {
4054 local *dbline = $main::{ '_<' . $file };
4057 for ( $i = 1 ; $i <= $max ; $i++ ) {
4058 if ( defined $dbline{$i} ) {
4059 $dbline{$i} =~ s/\0[^\0]*//;
4060 delete $dbline{$i} if $dbline{$i} eq '';
4062 unless ( $had_breakpoints{$file} &= ~2 ) {
4063 delete $had_breakpoints{$file};
4065 } ## end for ($i = 1 ; $i <= $max...
4066 } ## end for my $file (keys %had_breakpoints)
4067 } ## end else [ if (defined($i))
4068 } ## end sub delete_action
4070 =head3 C<cmd_b> (command)
4072 Set breakpoints. Since breakpoints can be set in so many places, in so many
4073 ways, conditionally or not, the breakpoint code is kind of complex. Mostly,
4074 we try to parse the command type, and then shuttle it off to an appropriate
4075 subroutine to actually do the work of setting the breakpoint in the right
4082 my $line = shift; # [.|line] [cond]
4085 # Make . the current line number if it's there..
4086 $line =~ s/^\./$dbline/;
4088 # No line number, no condition. Simple break on current line.
4089 if ( $line =~ /^\s*$/ ) {
4090 &cmd_b_line( $dbline, 1 );
4093 # Break on load for a file.
4094 elsif ( $line =~ /^load\b\s*(.*)/ ) {
4100 # b compile|postpone <some sub> [<condition>]
4101 # The interpreter actually traps this one for us; we just put the
4102 # necessary condition in the %postponed hash.
4103 elsif ( $line =~ /^(postpone|compile)\b\s*([':A-Za-z_][':\w]*)\s*(.*)/ ) {
4105 # Capture the condition if there is one. Make it true if none.
4106 my $cond = length $3 ? $3 : '1';
4108 # Save the sub name and set $break to 1 if $1 was 'postpone', 0
4109 # if it was 'compile'.
4110 my ( $subname, $break ) = ( $2, $1 eq 'postpone' );
4112 # De-Perl4-ify the name - ' separators to ::.
4113 $subname =~ s/\'/::/g;
4115 # Qualify it into the current package unless it's already qualified.
4116 $subname = "${'package'}::" . $subname unless $subname =~ /::/;
4118 # Add main if it starts with ::.
4119 $subname = "main" . $subname if substr( $subname, 0, 2 ) eq "::";
4121 # Save the break type for this sub.
4122 $postponed{$subname} = $break ? "break +0 if $cond" : "compile";
4123 } ## end elsif ($line =~ ...
4125 # b <sub name> [<condition>]
4126 elsif ( $line =~ /^([':A-Za-z_][':\w]*(?:\[.*\])?)\s*(.*)/ ) {
4130 $cond = length $2 ? $2 : '1';
4131 &cmd_b_sub( $subname, $cond );
4134 # b <line> [<condition>].
4135 elsif ( $line =~ /^(\d*)\s*(.*)/ ) {
4137 # Capture the line. If none, it's the current line.
4138 $line = $1 || $dbline;
4140 # If there's no condition, make it '1'.
4141 $cond = length $2 ? $2 : '1';
4144 &cmd_b_line( $line, $cond );
4147 # Line didn't make sense.
4149 print "confused by line($line)?\n";
4153 =head3 C<break_on_load> (API)
4155 We want to break when this file is loaded. Mark this file in the
4156 C<%break_on_load> hash, and note that it has a breakpoint in
4157 C<%had_breakpoints>.
4163 $break_on_load{$file} = 1;
4164 $had_breakpoints{$file} |= 1;
4167 =head3 C<report_break_on_load> (API)
4169 Gives us an array of filenames that are set to break on load. Note that
4170 only files with break-on-load are in here, so simply showing the keys
4175 sub report_break_on_load {
4176 sort keys %break_on_load;
4179 =head3 C<cmd_b_load> (command)
4181 We take the file passed in and try to find it in C<%INC> (which maps modules
4182 to files they came from). We mark those files for break-on-load via
4183 C<break_on_load> and then report that it was done.
4191 # This is a block because that way we can use a redo inside it
4192 # even without there being any looping structure at all outside it.
4195 # Save short name and full path if found.
4197 push @files, $::INC{$file} if $::INC{$file};
4199 # Tack on .pm and do it again unless there was a '.' in the name
4201 $file .= '.pm', redo unless $file =~ /\./;
4204 # Do the real work here.
4205 break_on_load($_) for @files;
4207 # All the files that have break-on-load breakpoints.
4208 @files = report_break_on_load;
4210 # Normalize for the purposes of our printing this.
4213 print $OUT "Will stop on load of `@files'.\n";
4214 } ## end sub cmd_b_load
4216 =head3 C<$filename_error> (API package global)
4218 Several of the functions we need to implement in the API need to work both
4219 on the current file and on other files. We don't want to duplicate code, so
4220 C<$filename_error> is used to contain the name of the file that's being
4221 worked on (if it's not the current one).
4223 We can now build functions in pairs: the basic function works on the current
4224 file, and uses C<$filename_error> as part of its error message. Since this is
4225 initialized to C<"">, no filename will appear when we are working on the
4228 The second function is a wrapper which does the following:
4234 Localizes C<$filename_error> and sets it to the name of the file to be processed.
4238 Localizes the C<*dbline> glob and reassigns it to point to the file we want to process.
4242 Calls the first function.
4244 The first function works on the I<current> file (i.e., the one we changed to),
4245 and prints C<$filename_error> in the error message (the name of the other file)
4246 if it needs to. When the functions return, C<*dbline> is restored to point
4247 to the actual current file (the one we're executing in) and
4248 C<$filename_error> is restored to C<"">. This restores everything to
4249 the way it was before the second function was called at all.
4251 See the comments in C<breakable_line> and C<breakable_line_in_file> for more
4258 $filename_error = '';
4260 =head3 breakable_line(from, to) (API)
4262 The subroutine decides whether or not a line in the current file is breakable.
4263 It walks through C<@dbline> within the range of lines specified, looking for
4264 the first line that is breakable.
4266 If C<$to> is greater than C<$from>, the search moves forwards, finding the
4267 first line I<after> C<$to> that's breakable, if there is one.
4269 If C<$from> is greater than C<$to>, the search goes I<backwards>, finding the
4270 first line I<before> C<$to> that's breakable, if there is one.
4274 sub breakable_line {
4276 my ( $from, $to ) = @_;
4278 # $i is the start point. (Where are the FORTRAN programs of yesteryear?)
4281 # If there are at least 2 arguments, we're trying to search a range.
4284 # $delta is positive for a forward search, negative for a backward one.
4285 my $delta = $from < $to ? +1 : -1;
4287 # Keep us from running off the ends of the file.
4288 my $limit = $delta > 0 ? $#dbline : 1;
4290 # Clever test. If you're a mathematician, it's obvious why this
4291 # test works. If not:
4292 # If $delta is positive (going forward), $limit will be $#dbline.
4293 # If $to is less than $limit, ($limit - $to) will be positive, times
4294 # $delta of 1 (positive), so the result is > 0 and we should use $to
4295 # as the stopping point.
4297 # If $to is greater than $limit, ($limit - $to) is negative,
4298 # times $delta of 1 (positive), so the result is < 0 and we should
4299 # use $limit ($#dbline) as the stopping point.
4301 # If $delta is negative (going backward), $limit will be 1.
4302 # If $to is zero, ($limit - $to) will be 1, times $delta of -1
4303 # (negative) so the result is > 0, and we use $to as the stopping
4306 # If $to is less than zero, ($limit - $to) will be positive,
4307 # times $delta of -1 (negative), so the result is not > 0, and
4308 # we use $limit (1) as the stopping point.
4310 # If $to is 1, ($limit - $to) will zero, times $delta of -1
4311 # (negative), still giving zero; the result is not > 0, and
4312 # we use $limit (1) as the stopping point.
4314 # if $to is >1, ($limit - $to) will be negative, times $delta of -1
4315 # (negative), giving a positive (>0) value, so we'll set $limit to
4318 $limit = $to if ( $limit - $to ) * $delta > 0;
4320 # The real search loop.
4321 # $i starts at $from (the point we want to start searching from).
4322 # We move through @dbline in the appropriate direction (determined
4323 # by $delta: either -1 (back) or +1 (ahead).
4324 # We stay in as long as we haven't hit an executable line
4325 # ($dbline[$i] == 0 means not executable) and we haven't reached
4326 # the limit yet (test similar to the above).
4327 $i += $delta while $dbline[$i] == 0 and ( $limit - $i ) * $delta > 0;
4329 } ## end if (@_ >= 2)
4331 # If $i points to a line that is executable, return that.
4332 return $i unless $dbline[$i] == 0;
4334 # Format the message and print it: no breakable lines in range.
4335 my ( $pl, $upto ) = ( '', '' );
4336 ( $pl, $upto ) = ( 's', "..$to" ) if @_ >= 2 and $from != $to;
4338 # If there's a filename in filename_error, we'll see it.
4340 die "Line$pl $from$upto$filename_error not breakable\n";
4341 } ## end sub breakable_line
4343 =head3 breakable_line_in_filename(file, from, to) (API)
4345 Like C<breakable_line>, but look in another file.
4349 sub breakable_line_in_filename {
4351 # Capture the file name.
4354 # Swap the magic line array over there temporarily.
4355 local *dbline = $main::{ '_<' . $f };
4357 # If there's an error, it's in this other file.
4358 local $filename_error = " of `$f'";
4360 # Find the breakable line.
4363 # *dbline and $filename_error get restored when this block ends.
4365 } ## end sub breakable_line_in_filename
4367 =head3 break_on_line(lineno, [condition]) (API)
4369 Adds a breakpoint with the specified condition (or 1 if no condition was
4370 specified) to the specified line. Dies if it can't.
4375 my ( $i, $cond ) = @_;
4377 # Always true if no condition supplied.
4378 $cond = 1 unless @_ >= 2;
4384 # Woops, not a breakable line. $filename_error allows us to say
4385 # if it was in a different file.
4386 die "Line $i$filename_error not breakable.\n" if $dbline[$i] == 0;
4388 # Mark this file as having breakpoints in it.
4389 $had_breakpoints{$filename} |= 1;
4391 # If there is an action or condition here already ...
4392 if ( $dbline{$i} ) {
4394 # ... swap this condition for the existing one.
4395 $dbline{$i} =~ s/^[^\0]*/$cond/;
4399 # Nothing here - just add the condition.
4400 $dbline{$i} = $cond;
4402 } ## end sub break_on_line
4404 =head3 cmd_b_line(line, [condition]) (command)
4406 Wrapper for C<break_on_line>. Prints the failure message if it
4412 eval { break_on_line(@_); 1 } or do {
4414 print $OUT $@ and return;
4416 } ## end sub cmd_b_line
4418 =head3 break_on_filename_line(file, line, [condition]) (API)
4420 Switches to the file specified and then calls C<break_on_line> to set
4425 sub break_on_filename_line {
4426 my ( $f, $i, $cond ) = @_;
4428 # Always true if condition left off.
4429 $cond = 1 unless @_ >= 3;
4431 # Switch the magical hash temporarily.
4432 local *dbline = $main::{ '_<' . $f };
4434 # Localize the variables that break_on_line uses to make its message.
4435 local $filename_error = " of `$f'";
4436 local $filename = $f;
4438 # Add the breakpoint.
4439 break_on_line( $i, $cond );
4440 } ## end sub break_on_filename_line
4442 =head3 break_on_filename_line_range(file, from, to, [condition]) (API)
4444 Switch to another file, search the range of lines specified for an
4445 executable one, and put a breakpoint on the first one you find.
4449 sub break_on_filename_line_range {
4450 my ( $f, $from, $to, $cond ) = @_;
4452 # Find a breakable line if there is one.
4453 my $i = breakable_line_in_filename( $f, $from, $to );
4455 # Always true if missing.
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