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>
177 via glob assignment) contains the text from C<$filename>, with each
178 element corresponding to a single line of C<$filename>. Additionally,
179 breakable lines will be dualvars with the numeric component being the
180 memory address of a COP node. Non-breakable lines are dualvar to 0.
182 The hash C<%{'_<'.$filename}> (aliased locally to C<%dbline> via glob
183 assignment) contains breakpoints and actions. The keys are line numbers;
184 you can set individual values, but not the whole hash. The Perl interpreter
185 uses this hash to determine where breakpoints have been set. Any true value is
186 considered to be a breakpoint; C<perl5db.pl> uses C<$break_condition\0$action>.
187 Values are magical in numeric context: 1 if the line is breakable, 0 if not.
189 The scalar C<${"_<$filename"}> simply contains the string C<_<$filename>.
190 This is also the case for evaluated strings that contain subroutines, or
191 which are currently being executed. The $filename for C<eval>ed strings looks
192 like C<(eval 34)> or C<(re_eval 19)>.
194 =head1 DEBUGGER STARTUP
196 When C<perl5db.pl> starts, it reads an rcfile (C<perl5db.ini> for
197 non-interactive sessions, C<.perldb> for interactive ones) that can set a number
198 of options. In addition, this file may define a subroutine C<&afterinit>
199 that will be executed (in the debugger's context) after the debugger has
202 Next, it checks the C<PERLDB_OPTS> environment variable and treats its
203 contents as the argument of a C<o> command in the debugger.
205 =head2 STARTUP-ONLY OPTIONS
207 The following options can only be specified at startup.
208 To set them in your rcfile, add a call to
209 C<&parse_options("optionName=new_value")>.
215 the TTY to use for debugging i/o.
219 if set, goes in NonStop mode. On interrupt, if TTY is not set,
220 uses the value of noTTY or F<$HOME/.perldbtty$$> to find TTY using
221 Term::Rendezvous. Current variant is to have the name of TTY in this
226 if false, a dummy ReadLine is used, so you can debug
227 ReadLine applications.
231 if true, no i/o is performed until interrupt.
235 file or pipe to print line number info to. If it is a
236 pipe, a short "emacs like" message is used.
240 host:port to connect to on remote host for remote debugging.
244 file to store session history to. There is no default and so no
245 history file is written unless this variable is explicitly set.
249 number of commands to store to the file specified in C<HistFile>.
256 &parse_options("NonStop=1 LineInfo=db.out");
257 sub afterinit { $trace = 1; }
259 The script will run without human intervention, putting trace
260 information into C<db.out>. (If you interrupt it, you had better
261 reset C<LineInfo> to something I<interactive>!)
263 =head1 INTERNALS DESCRIPTION
265 =head2 DEBUGGER INTERFACE VARIABLES
267 Perl supplies the values for C<%sub>. It effectively inserts
268 a C<&DB::DB();> in front of each place that can have a
269 breakpoint. At each subroutine call, it calls C<&DB::sub> with
270 C<$DB::sub> set to the called subroutine. It also inserts a C<BEGIN
271 {require 'perl5db.pl'}> before the first line.
273 After each C<require>d file is compiled, but before it is executed, a
274 call to C<&DB::postponed($main::{'_<'.$filename})> is done. C<$filename>
275 is the expanded name of the C<require>d file (as found via C<%INC>).
277 =head3 IMPORTANT INTERNAL VARIABLES
281 Used to control when the debugger will attempt to acquire another TTY to be
286 =item * 1 - on C<fork()>
288 =item * 2 - debugger is started inside debugger
290 =item * 4 - on startup
296 The value -2 indicates that no return value should be printed.
297 Any other positive value causes C<DB::sub> to print return values.
301 The item to be eval'ed by C<DB::eval>. Used to prevent messing with the current
302 contents of C<@_> when C<DB::eval> is called.
306 Determines what messages (if any) will get printed when a subroutine (or eval)
307 is entered or exited.
311 =item * 0 - No enter/exit messages
313 =item * 1 - Print I<entering> messages on subroutine entry
315 =item * 2 - Adds exit messages on subroutine exit. If no other flag is on, acts like 1+2.
317 =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.
319 =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.
321 =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.
325 To get everything, use C<$frame=30> (or C<o f=30> as a debugger command).
326 The debugger internally juggles the value of C<$frame> during execution to
327 protect external modules that the debugger uses from getting traced.
331 Tracks current debugger nesting level. Used to figure out how many
332 C<E<lt>E<gt>> pairs to surround the line number with when the debugger
333 outputs a prompt. Also used to help determine if the program has finished
334 during command parsing.
336 =head4 C<$onetimeDump>
338 Controls what (if anything) C<DB::eval()> will print after evaluating an
343 =item * C<undef> - don't print anything
345 =item * C<dump> - use C<dumpvar.pl> to display the value returned
347 =item * C<methods> - print the methods callable on the first item returned
351 =head4 C<$onetimeDumpDepth>
353 Controls how far down C<dumpvar.pl> will go before printing C<...> while
354 dumping a structure. Numeric. If C<undef>, print all levels.
358 Used to track whether or not an C<INT> signal has been detected. C<DB::DB()>,
359 which is called before every statement, checks this and puts the user into
360 command mode if it finds C<$signal> set to a true value.
364 Controls behavior during single-stepping. Stacked in C<@stack> on entry to
365 each subroutine; popped again at the end of each subroutine.
369 =item * 0 - run continuously.
371 =item * 1 - single-step, go into subs. The C<s> command.
373 =item * 2 - single-step, don't go into subs. The C<n> command.
375 =item * 4 - print current sub depth (turned on to force this when C<too much
382 Controls the output of trace information.
386 =item * 1 - The C<t> command was entered to turn on tracing (every line executed is printed)
388 =item * 2 - watch expressions are active
390 =item * 4 - user defined a C<watchfunction()> in C<afterinit()>
394 =head4 C<$slave_editor>
396 1 if C<LINEINFO> was directed to a pipe; 0 otherwise.
400 Stack of filehandles that C<DB::readline()> will read commands from.
401 Manipulated by the debugger's C<source> command and C<DB::readline()> itself.
405 Local alias to the magical line array, C<@{$main::{'_<'.$filename}}> ,
406 supplied by the Perl interpreter to the debugger. Contains the source.
410 Previous values of watch expressions. First set when the expression is
411 entered; reset whenever the watch expression changes.
415 Saves important globals (C<$@>, C<$!>, C<$^E>, C<$,>, C<$/>, C<$\>, C<$^W>)
416 so that the debugger can substitute safe values while it's running, and
417 restore them when it returns control.
421 Saves the current value of C<$single> on entry to a subroutine.
422 Manipulated by the C<c> command to turn off tracing in all subs above the
427 The 'watch' expressions: to be evaluated before each line is executed.
431 The typeahead buffer, used by C<DB::readline>.
435 Command aliases. Stored as character strings to be substituted for a command
438 =head4 C<%break_on_load>
440 Keys are file names, values are 1 (break when this file is loaded) or undef
441 (don't break when it is loaded).
445 Keys are line numbers, values are C<condition\0action>. If used in numeric
446 context, values are 0 if not breakable, 1 if breakable, no matter what is
447 in the actual hash entry.
449 =head4 C<%had_breakpoints>
451 Keys are file names; values are bitfields:
455 =item * 1 - file has a breakpoint in it.
457 =item * 2 - file has an action in it.
461 A zero or undefined value means this file has neither.
465 Stores the debugger options. These are character string values.
469 Saves breakpoints for code that hasn't been compiled yet.
470 Keys are subroutine names, values are:
474 =item * C<compile> - break when this sub is compiled
476 =item * C<< break +0 if <condition> >> - break (conditionally) at the start of this routine. The condition will be '1' if no condition was specified.
480 =head4 C<%postponed_file>
482 This hash keeps track of breakpoints that need to be set for files that have
483 not yet been compiled. Keys are filenames; values are references to hashes.
484 Each of these hashes is keyed by line number, and its values are breakpoint
485 definitions (C<condition\0action>).
487 =head1 DEBUGGER INITIALIZATION
489 The debugger's initialization actually jumps all over the place inside this
490 package. This is because there are several BEGIN blocks (which of course
491 execute immediately) spread through the code. Why is that?
493 The debugger needs to be able to change some things and set some things up
494 before the debugger code is compiled; most notably, the C<$deep> variable that
495 C<DB::sub> uses to tell when a program has recursed deeply. In addition, the
496 debugger has to turn off warnings while the debugger code is compiled, but then
497 restore them to their original setting before the program being debugged begins
500 The first C<BEGIN> block simply turns off warnings by saving the current
501 setting of C<$^W> and then setting it to zero. The second one initializes
502 the debugger variables that are needed before the debugger begins executing.
503 The third one puts C<$^X> back to its former value.
505 We'll detail the second C<BEGIN> block later; just remember that if you need
506 to initialize something before the debugger starts really executing, that's
513 BEGIN {eval 'use IO::Handle'}; # Needed for flush only? breaks under miniperl
515 # Debugger for Perl 5.00x; perl5db.pl patch level:
518 $header = "perl5db.pl version $VERSION";
520 =head1 DEBUGGER ROUTINES
524 This function replaces straight C<eval()> inside the debugger; it simplifies
525 the process of evaluating code in the user's context.
527 The code to be evaluated is passed via the package global variable
528 C<$DB::evalarg>; this is done to avoid fiddling with the contents of C<@_>.
530 Before we do the C<eval()>, we preserve the current settings of C<$trace>,
531 C<$single>, C<$^D> and C<$usercontext>. The latter contains the
532 preserved values of C<$@>, C<$!>, C<$^E>, C<$,>, C<$/>, C<$\>, C<$^W> and the
533 user's current package, grabbed when C<DB::DB> got control. This causes the
534 proper context to be used when the eval is actually done. Afterward, we
535 restore C<$trace>, C<$single>, and C<$^D>.
537 Next we need to handle C<$@> without getting confused. We save C<$@> in a
538 local lexical, localize C<$saved[0]> (which is where C<save()> will put
539 C<$@>), and then call C<save()> to capture C<$@>, C<$!>, C<$^E>, C<$,>,
540 C<$/>, C<$\>, and C<$^W>) and set C<$,>, C<$/>, C<$\>, and C<$^W> to values
541 considered sane by the debugger. If there was an C<eval()> error, we print
542 it on the debugger's output. If C<$onetimedump> is defined, we call
543 C<dumpit> if it's set to 'dump', or C<methods> if it's set to
544 'methods'. Setting it to something else causes the debugger to do the eval
545 but not print the result - handy if you want to do something else with it
546 (the "watch expressions" code does this to get the value of the watch
547 expression but not show it unless it matters).
549 In any case, we then return the list of output from C<eval> to the caller,
550 and unwinding restores the former version of C<$@> in C<@saved> as well
551 (the localization of C<$saved[0]> goes away at the end of this scope).
553 =head3 Parameters and variables influencing execution of DB::eval()
555 C<DB::eval> isn't parameterized in the standard way; this is to keep the
556 debugger's calls to C<DB::eval()> from mucking with C<@_>, among other things.
557 The variables listed below influence C<DB::eval()>'s execution directly.
561 =item C<$evalarg> - the thing to actually be eval'ed
563 =item C<$trace> - Current state of execution tracing
565 =item C<$single> - Current state of single-stepping
567 =item C<$onetimeDump> - what is to be displayed after the evaluation
569 =item C<$onetimeDumpDepth> - how deep C<dumpit()> should go when dumping results
573 The following variables are altered by C<DB::eval()> during its execution. They
574 are "stacked" via C<local()>, enabling recursive calls to C<DB::eval()>.
578 =item C<@res> - used to capture output from actual C<eval>.
580 =item C<$otrace> - saved value of C<$trace>.
582 =item C<$osingle> - saved value of C<$single>.
584 =item C<$od> - saved value of C<$^D>.
586 =item C<$saved[0]> - saved value of C<$@>.
588 =item $\ - for output of C<$@> if there is an evaluation error.
592 =head3 The problem of lexicals
594 The context of C<DB::eval()> presents us with some problems. Obviously,
595 we want to be 'sandboxed' away from the debugger's internals when we do
596 the eval, but we need some way to control how punctuation variables and
597 debugger globals are used.
599 We can't use local, because the code inside C<DB::eval> can see localized
600 variables; and we can't use C<my> either for the same reason. The code
601 in this routine compromises and uses C<my>.
603 After this routine is over, we don't have user code executing in the debugger's
604 context, so we can use C<my> freely.
608 ############################################## Begin lexical danger zone
610 # 'my' variables used here could leak into (that is, be visible in)
611 # the context that the code being evaluated is executing in. This means that
612 # the code could modify the debugger's variables.
614 # Fiddling with the debugger's context could be Bad. We insulate things as
619 # 'my' would make it visible from user code
620 # but so does local! --tchrist
621 # Remember: this localizes @DB::res, not @main::res.
625 # Try to keep the user code from messing with us. Save these so that
626 # even if the eval'ed code changes them, we can put them back again.
627 # Needed because the user could refer directly to the debugger's
628 # package globals (and any 'my' variables in this containing scope)
629 # inside the eval(), and we want to try to stay safe.
630 local $otrace = $trace;
631 local $osingle = $single;
634 # Untaint the incoming eval() argument.
635 { ($evalarg) = $evalarg =~ /(.*)/s; }
637 # $usercontext built in DB::DB near the comment
638 # "set up the context for DB::eval ..."
639 # Evaluate and save any results.
640 @res = eval "$usercontext $evalarg;\n"; # '\n' for nice recursive debug
642 # Restore those old values.
648 # Save the current value of $@, and preserve it in the debugger's copy
649 # of the saved precious globals.
652 # Since we're only saving $@, we only have to localize the array element
653 # that it will be stored in.
654 local $saved[0]; # Preserve the old value of $@
657 # Now see whether we need to report an error back to the user.
663 # Display as required by the caller. $onetimeDump and $onetimedumpDepth
664 # are package globals.
665 elsif ($onetimeDump) {
666 if ( $onetimeDump eq 'dump' ) {
667 local $option{dumpDepth} = $onetimedumpDepth
668 if defined $onetimedumpDepth;
669 dumpit( $OUT, \@res );
671 elsif ( $onetimeDump eq 'methods' ) {
674 } ## end elsif ($onetimeDump)
678 ############################################## End lexical danger zone
680 # After this point it is safe to introduce lexicals.
681 # The code being debugged will be executing in its own context, and
682 # can't see the inside of the debugger.
684 # However, one should not overdo it: leave as much control from outside as
685 # possible. If you make something a lexical, it's not going to be addressable
686 # from outside the debugger even if you know its name.
688 # This file is automatically included if you do perl -d.
689 # It's probably not useful to include this yourself.
691 # Before venturing further into these twisty passages, it is
692 # wise to read the perldebguts man page or risk the ire of dragons.
694 # (It should be noted that perldebguts will tell you a lot about
695 # the underlying mechanics of how the debugger interfaces into the
696 # Perl interpreter, but not a lot about the debugger itself. The new
697 # comments in this code try to address this problem.)
699 # Note that no subroutine call is possible until &DB::sub is defined
700 # (for subroutines defined outside of the package DB). In fact the same is
701 # true if $deep is not defined.
703 # Enhanced by ilya@math.ohio-state.edu (Ilya Zakharevich)
705 # modified Perl debugger, to be run from Emacs in perldb-mode
706 # Ray Lischner (uunet!mntgfx!lisch) as of 5 Nov 1990
707 # Johan Vromans -- upgrade to 4.0 pl 10
708 # Ilya Zakharevich -- patches after 5.001 (and some before ;-)
710 # (We have made efforts to clarify the comments in the change log
711 # in other places; some of them may seem somewhat obscure as they
712 # were originally written, and explaining them away from the code
713 # in question seems conterproductive.. -JM)
715 ########################################################################
717 # + A lot of things changed after 0.94. First of all, core now informs
718 # debugger about entry into XSUBs, overloaded operators, tied operations,
719 # BEGIN and END. Handy with `O f=2'.
720 # + This can make debugger a little bit too verbose, please be patient
721 # and report your problems promptly.
722 # + Now the option frame has 3 values: 0,1,2. XXX Document!
723 # + Note that if DESTROY returns a reference to the object (or object),
724 # the deletion of data may be postponed until the next function call,
725 # due to the need to examine the return value.
728 # + `v' command shows versions.
731 # + `v' command shows version of readline.
732 # primitive completion works (dynamic variables, subs for `b' and `l',
733 # options). Can `p %var'
734 # + Better help (`h <' now works). New commands <<, >>, {, {{.
735 # {dump|print}_trace() coded (to be able to do it from <<cmd).
736 # + `c sub' documented.
737 # + At last enough magic combined to stop after the end of debuggee.
738 # + !! should work now (thanks to Emacs bracket matching an extra
739 # `]' in a regexp is caught).
740 # + `L', `D' and `A' span files now (as documented).
741 # + Breakpoints in `require'd code are possible (used in `R').
742 # + Some additional words on internal work of debugger.
743 # + `b load filename' implemented.
744 # + `b postpone subr' implemented.
745 # + now only `q' exits debugger (overwritable on $inhibit_exit).
746 # + When restarting debugger breakpoints/actions persist.
747 # + Buglet: When restarting debugger only one breakpoint/action per
748 # autoloaded function persists.
750 # Changes: 0.97: NonStop will not stop in at_exit().
751 # + Option AutoTrace implemented.
752 # + Trace printed differently if frames are printed too.
753 # + new `inhibitExit' option.
754 # + printing of a very long statement interruptible.
755 # Changes: 0.98: New command `m' for printing possible methods
756 # + 'l -' is a synonym for `-'.
757 # + Cosmetic bugs in printing stack trace.
758 # + `frame' & 8 to print "expanded args" in stack trace.
759 # + Can list/break in imported subs.
760 # + new `maxTraceLen' option.
761 # + frame & 4 and frame & 8 granted.
763 # + nonstoppable lines do not have `:' near the line number.
764 # + `b compile subname' implemented.
765 # + Will not use $` any more.
766 # + `-' behaves sane now.
767 # Changes: 0.99: Completion for `f', `m'.
768 # + `m' will remove duplicate names instead of duplicate functions.
769 # + `b load' strips trailing whitespace.
770 # completion ignores leading `|'; takes into account current package
771 # when completing a subroutine name (same for `l').
772 # Changes: 1.07: Many fixed by tchrist 13-March-2000
774 # + Added bare minimal security checks on perldb rc files, plus
775 # comments on what else is needed.
776 # + Fixed the ornaments that made "|h" completely unusable.
777 # They are not used in print_help if they will hurt. Strip pod
778 # if we're paging to less.
779 # + Fixed mis-formatting of help messages caused by ornaments
780 # to restore Larry's original formatting.
781 # + Fixed many other formatting errors. The code is still suboptimal,
782 # and needs a lot of work at restructuring. It's also misindented
784 # + Fixed bug where trying to look at an option like your pager
786 # + Fixed some $? processing. Note: if you use csh or tcsh, you will
787 # lose. You should consider shell escapes not using their shell,
788 # or else not caring about detailed status. This should really be
789 # unified into one place, too.
790 # + Fixed bug where invisible trailing whitespace on commands hoses you,
791 # tricking Perl into thinking you weren't calling a debugger command!
792 # + Fixed bug where leading whitespace on commands hoses you. (One
793 # suggests a leading semicolon or any other irrelevant non-whitespace
794 # to indicate literal Perl code.)
795 # + Fixed bugs that ate warnings due to wrong selected handle.
796 # + Fixed a precedence bug on signal stuff.
797 # + Fixed some unseemly wording.
798 # + Fixed bug in help command trying to call perl method code.
799 # + Fixed to call dumpvar from exception handler. SIGPIPE killed us.
801 # + Added some comments. This code is still nasty spaghetti.
802 # + Added message if you clear your pre/post command stacks which was
803 # very easy to do if you just typed a bare >, <, or {. (A command
804 # without an argument should *never* be a destructive action; this
805 # API is fundamentally screwed up; likewise option setting, which
806 # is equally buggered.)
807 # + Added command stack dump on argument of "?" for >, <, or {.
808 # + Added a semi-built-in doc viewer command that calls man with the
809 # proper %Config::Config path (and thus gets caching, man -k, etc),
810 # or else perldoc on obstreperous platforms.
811 # + Added to and rearranged the help information.
812 # + Detected apparent misuse of { ... } to declare a block; this used
813 # to work but now is a command, and mysteriously gave no complaint.
815 # Changes: 1.08: Apr 25, 2001 Jon Eveland <jweveland@yahoo.com>
817 # + This patch to perl5db.pl cleans up formatting issues on the help
818 # summary (h h) screen in the debugger. Mostly columnar alignment
819 # issues, plus converted the printed text to use all spaces, since
820 # tabs don't seem to help much here.
822 # Changes: 1.09: May 19, 2001 Ilya Zakharevich <ilya@math.ohio-state.edu>
823 # Minor bugs corrected;
824 # + Support for auto-creation of new TTY window on startup, either
825 # unconditionally, or if started as a kid of another debugger session;
826 # + New `O'ption CreateTTY
827 # I<CreateTTY> bits control attempts to create a new TTY on events:
829 # 2: debugger is started inside debugger
831 # + Code to auto-create a new TTY window on OS/2 (currently one
832 # extra window per session - need named pipes to have more...);
833 # + Simplified interface for custom createTTY functions (with a backward
834 # compatibility hack); now returns the TTY name to use; return of ''
835 # means that the function reset the I/O handles itself;
836 # + Better message on the semantic of custom createTTY function;
837 # + Convert the existing code to create a TTY into a custom createTTY
839 # + Consistent support for TTY names of the form "TTYin,TTYout";
840 # + Switch line-tracing output too to the created TTY window;
841 # + make `b fork' DWIM with CORE::GLOBAL::fork;
842 # + High-level debugger API cmd_*():
843 # cmd_b_load($filenamepart) # b load filenamepart
844 # cmd_b_line($lineno [, $cond]) # b lineno [cond]
845 # cmd_b_sub($sub [, $cond]) # b sub [cond]
846 # cmd_stop() # Control-C
847 # cmd_d($lineno) # d lineno (B)
848 # The cmd_*() API returns FALSE on failure; in this case it outputs
849 # the error message to the debugging output.
850 # + Low-level debugger API
851 # break_on_load($filename) # b load filename
852 # @files = report_break_on_load() # List files with load-breakpoints
853 # breakable_line_in_filename($name, $from [, $to])
854 # # First breakable line in the
855 # # range $from .. $to. $to defaults
856 # # to $from, and may be less than
858 # breakable_line($from [, $to]) # Same for the current file
859 # break_on_filename_line($name, $lineno [, $cond])
860 # # Set breakpoint,$cond defaults to
862 # break_on_filename_line_range($name, $from, $to [, $cond])
863 # # As above, on the first
864 # # breakable line in range
865 # break_on_line($lineno [, $cond]) # As above, in the current file
866 # break_subroutine($sub [, $cond]) # break on the first breakable line
867 # ($name, $from, $to) = subroutine_filename_lines($sub)
868 # # The range of lines of the text
869 # The low-level API returns TRUE on success, and die()s on failure.
871 # Changes: 1.10: May 23, 2001 Daniel Lewart <d-lewart@uiuc.edu>
873 # + Fixed warnings generated by "perl -dWe 42"
874 # + Corrected spelling errors
875 # + Squeezed Help (h) output into 80 columns
877 # Changes: 1.11: May 24, 2001 David Dyck <dcd@tc.fluke.com>
878 # + Made "x @INC" work like it used to
880 # Changes: 1.12: May 24, 2001 Daniel Lewart <d-lewart@uiuc.edu>
881 # + Fixed warnings generated by "O" (Show debugger options)
882 # + Fixed warnings generated by "p 42" (Print expression)
883 # Changes: 1.13: Jun 19, 2001 Scott.L.Miller@compaq.com
884 # + Added windowSize option
885 # Changes: 1.14: Oct 9, 2001 multiple
886 # + Clean up after itself on VMS (Charles Lane in 12385)
887 # + Adding "@ file" syntax (Peter Scott in 12014)
888 # + Debug reloading selfloaded stuff (Ilya Zakharevich in 11457)
889 # + $^S and other debugger fixes (Ilya Zakharevich in 11120)
890 # + Forgot a my() declaration (Ilya Zakharevich in 11085)
891 # Changes: 1.15: Nov 6, 2001 Michael G Schwern <schwern@pobox.com>
892 # + Updated 1.14 change log
893 # + Added *dbline explainatory comments
894 # + Mentioning perldebguts man page
895 # Changes: 1.16: Feb 15, 2002 Mark-Jason Dominus <mjd@plover.com>
896 # + $onetimeDump improvements
897 # Changes: 1.17: Feb 20, 2002 Richard Foley <richard.foley@rfi.net>
898 # Moved some code to cmd_[.]()'s for clarity and ease of handling,
899 # rationalised the following commands and added cmd_wrapper() to
900 # enable switching between old and frighteningly consistent new
901 # behaviours for diehards: 'o CommandSet=pre580' (sigh...)
902 # a(add), A(del) # action expr (added del by line)
903 # + b(add), B(del) # break [line] (was b,D)
904 # + w(add), W(del) # watch expr (was W,W)
905 # # added del by expr
906 # + h(summary), h h(long) # help (hh) (was h h,h)
907 # + m(methods), M(modules) # ... (was m,v)
908 # + o(option) # lc (was O)
909 # + v(view code), V(view Variables) # ... (was w,V)
910 # Changes: 1.18: Mar 17, 2002 Richard Foley <richard.foley@rfi.net>
911 # + fixed missing cmd_O bug
912 # Changes: 1.19: Mar 29, 2002 Spider Boardman
913 # + Added missing local()s -- DB::DB is called recursively.
914 # Changes: 1.20: Feb 17, 2003 Richard Foley <richard.foley@rfi.net>
915 # + pre'n'post commands no longer trashed with no args
916 # + watch val joined out of eval()
917 # Changes: 1.21: Jun 04, 2003 Joe McMahon <mcmahon@ibiblio.org>
918 # + Added comments and reformatted source. No bug fixes/enhancements.
919 # + Includes cleanup by Robin Barker and Jarkko Hietaniemi.
920 # Changes: 1.22 Jun 09, 2003 Alex Vandiver <alexmv@MIT.EDU>
921 # + Flush stdout/stderr before the debugger prompt is printed.
922 # Changes: 1.23: Dec 21, 2003 Dominique Quatravaux
923 # + Fix a side-effect of bug #24674 in the perl debugger ("odd taint bug")
924 # Changes: 1.24: Mar 03, 2004 Richard Foley <richard.foley@rfi.net>
925 # + Added command to save all debugger commands for sourcing later.
926 # + Added command to display parent inheritance tree of given class.
927 # + Fixed minor newline in history bug.
928 # Changes: 1.25: Apr 17, 2004 Richard Foley <richard.foley@rfi.net>
929 # + Fixed option bug (setting invalid options + not recognising valid short forms)
930 # Changes: 1.26: Apr 22, 2004 Richard Foley <richard.foley@rfi.net>
931 # + unfork the 5.8.x and 5.9.x debuggers.
932 # + whitespace and assertions call cleanup across versions
933 # + H * deletes (resets) history
934 # + i now handles Class + blessed objects
935 # Changes: 1.27: May 09, 2004 Richard Foley <richard.foley@rfi.net>
936 # + updated pod page references - clunky.
937 # + removed windowid restriction for forking into an xterm.
938 # + more whitespace again.
939 # + wrapped restart and enabled rerun [-n] (go back n steps) command.
940 # Changes: 1.28: Oct 12, 2004 Richard Foley <richard.foley@rfi.net>
941 # + Added threads support (inc. e and E commands)
942 # Changes: 1.29: Nov 28, 2006 Bo Lindbergh <blgl@hagernas.com>
943 # + Added macosx_get_fork_TTY support
944 # Changes: 1.30: Mar 06, 2007 Andreas Koenig <andk@cpan.org>
945 # + Added HistFile, HistSize
947 # + Remove support for assertions and -A
948 # + stop NEXT::AUTOLOAD from emitting warnings under the debugger. RT #25053
949 # + "update for Mac OS X 10.5" [finding the tty device]
950 # + "What I needed to get the forked debugger to work" [on VMS]
951 # + [perl #57016] debugger: o warn=0 die=0 ignored
952 # + Note, but don't use, PERLDBf_SAVESRC
953 # + Fix #7013: lvalue subs not working inside debugger
954 # Changes: 1.32: Jun 03, 2009 Jonathan Leto <jonathan@leto.net>
955 # + Fix bug where a key _< with undefined value was put into the symbol table
956 # + when the $filename variable is not set
958 # + Debugger prints lines to the remote port when it forks and openes a new port (f633fd2)
959 # + The debugger now continues to use RemotePort when it's been configured to use it. (11653f7)
960 # + Stop using $ENV{LESS} for parameters not intended for less (d463cf2)
961 # + Configure has a path to less and perl5db.pl can use it (bf320d6)
962 # + Die with $@ instead of empty message (86755f4)
963 # + Remove extra/useless $@ check after eval { require PadWalker } (which is still checked) (dab8d6d)
964 # + Promote eval( "require ..." ) to eval { require ... } (4a49187)
965 # + Promote eval { require( ... )} || die to mere require( ... ) (999f23b)
966 # + Remove indirect object notation from debugger (bee4b46)
967 # + Document that @{$main::{'_<'.$filename}} lines are dualvar to (COP*). (7e17a74)
968 # + Remove MacOS classic support from the debugger. (2b894b7)
969 ########################################################################
971 =head1 DEBUGGER INITIALIZATION
973 The debugger starts up in phases.
977 First, it initializes the environment it wants to run in: turning off
978 warnings during its own compilation, defining variables which it will need
979 to avoid warnings later, setting itself up to not exit when the program
980 terminates, and defaulting to printing return values for the C<r> command.
984 # Needed for the statement after exec():
986 # This BEGIN block is simply used to switch off warnings during debugger
987 # compiliation. Probably it would be better practice to fix the warnings,
988 # but this is how it's done at the moment.
993 } # Switch compilation warnings off until another BEGIN.
995 local ($^W) = 0; # Switch run-time warnings off during init.
997 =head2 THREADS SUPPORT
999 If we are running under a threaded Perl, we require threads and threads::shared
1000 if the environment variable C<PERL5DB_THREADED> is set, to enable proper
1001 threaded debugger control. C<-dt> can also be used to set this.
1003 Each new thread will be announced and the debugger prompt will always inform
1004 you of each new thread created. It will also indicate the thread id in which
1005 we are currently running within the prompt like this:
1009 Where C<[tid]> is an integer thread id and C<$i> is the familiar debugger
1010 command prompt. The prompt will show: C<[0]> when running under threads, but
1011 not actually in a thread. C<[tid]> is consistent with C<gdb> usage.
1013 While running under threads, when you set or delete a breakpoint (etc.), this
1014 will apply to all threads, not just the currently running one. When you are
1015 in a currently executing thread, you will stay there until it completes. With
1016 the current implementation it is not currently possible to hop from one thread
1019 The C<e> and C<E> commands are currently fairly minimal - see C<h e> and C<h E>.
1021 Note that threading support was built into the debugger as of Perl version
1022 C<5.8.6> and debugger version C<1.2.8>.
1027 # ensure we can share our non-threaded variables or no-op
1028 if ($ENV{PERL5DB_THREADED}) {
1030 require threads::shared;
1031 import threads::shared qw(share);
1035 print "Threads support enabled\n";
1042 # This would probably be better done with "use vars", but that wasn't around
1043 # when this code was originally written. (Neither was "use strict".) And on
1044 # the principle of not fiddling with something that was working, this was
1047 # These variables control the execution of 'dumpvar.pl'.
1048 $dumpvar::hashDepth,
1049 $dumpvar::arrayDepth,
1050 $dumpvar::dumpDBFiles,
1051 $dumpvar::dumpPackages,
1052 $dumpvar::quoteHighBit,
1053 $dumpvar::printUndef,
1054 $dumpvar::globPrint,
1055 $dumpvar::usageOnly,
1057 # used to save @ARGV and extract any debugger-related flags.
1060 # used to control die() reporting in diesignal()
1063 # used to prevent multiple entries to diesignal()
1064 # (if for instance diesignal() itself dies)
1067 # used to prevent the debugger from running nonstop
1073 # without threads, $filename is not defined until DB::DB is called
1074 foreach my $k (keys (%INC)) {
1075 &share(\$main::{'_<'.$filename}) if defined $filename;
1078 # Command-line + PERLLIB:
1079 # Save the contents of @INC before they are modified elsewhere.
1082 # This was an attempt to clear out the previous values of various
1083 # trapped errors. Apparently it didn't help. XXX More info needed!
1084 # $prevwarn = $prevdie = $prevbus = $prevsegv = ''; # Does not help?!
1086 # We set these variables to safe values. We don't want to blindly turn
1087 # off warnings, because other packages may still want them.
1088 $trace = $signal = $single = 0; # Uninitialized warning suppression
1089 # (local $^W cannot help - other packages!).
1091 # Default to not exiting when program finishes; print the return
1092 # value when the 'r' command is used to return from a subroutine.
1093 $inhibit_exit = $option{PrintRet} = 1;
1095 =head1 OPTION PROCESSING
1097 The debugger's options are actually spread out over the debugger itself and
1098 C<dumpvar.pl>; some of these are variables to be set, while others are
1099 subs to be called with a value. To try to make this a little easier to
1100 manage, the debugger uses a few data structures to define what options
1101 are legal and how they are to be processed.
1103 First, the C<@options> array defines the I<names> of all the options that
1109 CommandSet HistFile HistSize
1110 hashDepth arrayDepth dumpDepth
1111 DumpDBFiles DumpPackages DumpReused
1112 compactDump veryCompact quote
1113 HighBit undefPrint globPrint
1114 PrintRet UsageOnly frame
1116 ReadLine NonStop LineInfo
1117 maxTraceLen recallCommand ShellBang
1118 pager tkRunning ornaments
1119 signalLevel warnLevel dieLevel
1120 inhibit_exit ImmediateStop bareStringify
1121 CreateTTY RemotePort windowSize
1125 @RememberOnROptions = qw(DollarCaretP);
1129 Second, C<optionVars> lists the variables that each option uses to save its
1135 hashDepth => \$dumpvar::hashDepth,
1136 arrayDepth => \$dumpvar::arrayDepth,
1137 CommandSet => \$CommandSet,
1138 DumpDBFiles => \$dumpvar::dumpDBFiles,
1139 DumpPackages => \$dumpvar::dumpPackages,
1140 DumpReused => \$dumpvar::dumpReused,
1141 HighBit => \$dumpvar::quoteHighBit,
1142 undefPrint => \$dumpvar::printUndef,
1143 globPrint => \$dumpvar::globPrint,
1144 UsageOnly => \$dumpvar::usageOnly,
1145 CreateTTY => \$CreateTTY,
1146 bareStringify => \$dumpvar::bareStringify,
1148 AutoTrace => \$trace,
1149 inhibit_exit => \$inhibit_exit,
1150 maxTraceLen => \$maxtrace,
1151 ImmediateStop => \$ImmediateStop,
1152 RemotePort => \$remoteport,
1153 windowSize => \$window,
1154 HistFile => \$histfile,
1155 HistSize => \$histsize,
1160 Third, C<%optionAction> defines the subroutine to be called to process each
1166 compactDump => \&dumpvar::compactDump,
1167 veryCompact => \&dumpvar::veryCompact,
1168 quote => \&dumpvar::quote,
1171 ReadLine => \&ReadLine,
1172 NonStop => \&NonStop,
1173 LineInfo => \&LineInfo,
1174 recallCommand => \&recallCommand,
1175 ShellBang => \&shellBang,
1177 signalLevel => \&signalLevel,
1178 warnLevel => \&warnLevel,
1179 dieLevel => \&dieLevel,
1180 tkRunning => \&tkRunning,
1181 ornaments => \&ornaments,
1182 RemotePort => \&RemotePort,
1183 DollarCaretP => \&DollarCaretP,
1188 Last, the C<%optionRequire> notes modules that must be C<require>d if an
1193 # Note that this list is not complete: several options not listed here
1194 # actually require that dumpvar.pl be loaded for them to work, but are
1195 # not in the table. A subsequent patch will correct this problem; for
1196 # the moment, we're just recommenting, and we are NOT going to change
1199 compactDump => 'dumpvar.pl',
1200 veryCompact => 'dumpvar.pl',
1201 quote => 'dumpvar.pl',
1206 There are a number of initialization-related variables which can be set
1207 by putting code to set them in a BEGIN block in the C<PERL5DB> environment
1208 variable. These are:
1212 =item C<$rl> - readline control XXX needs more explanation
1214 =item C<$warnLevel> - whether or not debugger takes over warning handling
1216 =item C<$dieLevel> - whether or not debugger takes over die handling
1218 =item C<$signalLevel> - whether or not debugger takes over signal handling
1220 =item C<$pre> - preprompt actions (array reference)
1222 =item C<$post> - postprompt actions (array reference)
1226 =item C<$CreateTTY> - whether or not to create a new TTY for this debugger
1228 =item C<$CommandSet> - which command set to use (defaults to new, documented set)
1234 # These guys may be defined in $ENV{PERL5DB} :
1235 $rl = 1 unless defined $rl;
1236 $warnLevel = 1 unless defined $warnLevel;
1237 $dieLevel = 1 unless defined $dieLevel;
1238 $signalLevel = 1 unless defined $signalLevel;
1239 $pre = [] unless defined $pre;
1240 $post = [] unless defined $post;
1241 $pretype = [] unless defined $pretype;
1242 $CreateTTY = 3 unless defined $CreateTTY;
1243 $CommandSet = '580' unless defined $CommandSet;
1248 share($signalLevel);
1258 The default C<die>, C<warn>, and C<signal> handlers are set up.
1262 warnLevel($warnLevel);
1263 dieLevel($dieLevel);
1264 signalLevel($signalLevel);
1268 The pager to be used is needed next. We try to get it from the
1269 environment first. If it's not defined there, we try to find it in
1270 the Perl C<Config.pm>. If it's not there, we default to C<more>. We
1271 then call the C<pager()> function to save the pager name.
1275 # This routine makes sure $pager is set up so that '|' can use it.
1278 # If PAGER is defined in the environment, use it.
1282 # If not, see if Config.pm defines it.
1283 : eval { require Config }
1284 && defined $Config::Config{pager}
1285 ? $Config::Config{pager}
1287 # If not, fall back to 'more'.
1290 unless defined $pager;
1294 We set up the command to be used to access the man pages, the command
1295 recall character (C<!> unless otherwise defined) and the shell escape
1296 character (C<!> unless otherwise defined). Yes, these do conflict, and
1297 neither works in the debugger at the moment.
1303 # Set up defaults for command recall and shell escape (note:
1304 # these currently don't work in linemode debugging).
1305 &recallCommand("!") unless defined $prc;
1306 &shellBang("!") unless defined $psh;
1310 We then set up the gigantic string containing the debugger help.
1311 We also set the limit on the number of arguments we'll display during a
1318 # If we didn't get a default for the length of eval/stack trace args,
1320 $maxtrace = 400 unless defined $maxtrace;
1322 =head2 SETTING UP THE DEBUGGER GREETING
1324 The debugger I<greeting> helps to inform the user how many debuggers are
1325 running, and whether the current debugger is the primary or a child.
1327 If we are the primary, we just hang onto our pid so we'll have it when
1328 or if we start a child debugger. If we are a child, we'll set things up
1329 so we'll have a unique greeting and so the parent will give us our own
1332 We save the current contents of the C<PERLDB_PIDS> environment variable
1333 because we mess around with it. We'll also need to hang onto it because
1334 we'll need it if we restart.
1336 Child debuggers make a label out of the current PID structure recorded in
1337 PERLDB_PIDS plus the new PID. They also mark themselves as not having a TTY
1338 yet so the parent will give them one later via C<resetterm()>.
1342 # Save the current contents of the environment; we're about to
1343 # much with it. We'll need this if we have to restart.
1344 $ini_pids = $ENV{PERLDB_PIDS};
1346 if ( defined $ENV{PERLDB_PIDS} ) {
1348 # We're a child. Make us a label out of the current PID structure
1349 # recorded in PERLDB_PIDS plus our (new) PID. Mark us as not having
1350 # a term yet so the parent will give us one later via resetterm().
1352 my $env_pids = $ENV{PERLDB_PIDS};
1353 $pids = "[$env_pids]";
1355 # Unless we are on OpenVMS, all programs under the DCL shell run under
1358 if (($^O eq 'VMS') && ($env_pids =~ /\b$$\b/)) {
1362 $ENV{PERLDB_PIDS} .= "->$$";
1366 } ## end if (defined $ENV{PERLDB_PIDS...
1369 # We're the parent PID. Initialize PERLDB_PID in case we end up with a
1370 # child debugger, and mark us as the parent, so we'll know to set up
1371 # more TTY's is we have to.
1372 $ENV{PERLDB_PIDS} = "$$";
1379 # Sets up $emacs as a synonym for $slave_editor.
1380 *emacs = $slave_editor if $slave_editor; # May be used in afterinit()...
1382 =head2 READING THE RC FILE
1384 The debugger will read a file of initialization options if supplied. If
1385 running interactively, this is C<.perldb>; if not, it's C<perldb.ini>.
1389 # As noted, this test really doesn't check accurately that the debugger
1390 # is running at a terminal or not.
1392 my $dev_tty = '/dev/tty';
1393 $dev_tty = 'TT:' if ($^O eq 'VMS');
1394 if ( -e $dev_tty ) { # this is the wrong metric!
1395 $rcfile = ".perldb";
1398 $rcfile = "perldb.ini";
1403 The debugger does a safety test of the file to be read. It must be owned
1404 either by the current user or root, and must only be writable by the owner.
1408 # This wraps a safety test around "do" to read and evaluate the init file.
1410 # This isn't really safe, because there's a race
1411 # between checking and opening. The solution is to
1412 # open and fstat the handle, but then you have to read and
1413 # eval the contents. But then the silly thing gets
1414 # your lexical scope, which is unfortunate at best.
1418 # Just exactly what part of the word "CORE::" don't you understand?
1419 local $SIG{__WARN__};
1420 local $SIG{__DIE__};
1422 unless ( is_safe_file($file) ) {
1423 CORE::warn <<EO_GRIPE;
1424 perldb: Must not source insecure rcfile $file.
1425 You or the superuser must be the owner, and it must not
1426 be writable by anyone but its owner.
1429 } ## end unless (is_safe_file($file...
1432 CORE::warn("perldb: couldn't parse $file: $@") if $@;
1433 } ## end sub safe_do
1435 # This is the safety test itself.
1437 # Verifies that owner is either real user or superuser and that no
1438 # one but owner may write to it. This function is of limited use
1439 # when called on a path instead of upon a handle, because there are
1440 # no guarantees that filename (by dirent) whose file (by ino) is
1441 # eventually accessed is the same as the one tested.
1442 # Assumes that the file's existence is not in doubt.
1445 stat($path) || return; # mysteriously vaporized
1446 my ( $dev, $ino, $mode, $nlink, $uid, $gid ) = stat(_);
1448 return 0 if $uid != 0 && $uid != $<;
1449 return 0 if $mode & 022;
1451 } ## end sub is_safe_file
1453 # If the rcfile (whichever one we decided was the right one to read)
1454 # exists, we safely do it.
1456 safe_do("./$rcfile");
1459 # If there isn't one here, try the user's home directory.
1460 elsif ( defined $ENV{HOME} && -f "$ENV{HOME}/$rcfile" ) {
1461 safe_do("$ENV{HOME}/$rcfile");
1464 # Else try the login directory.
1465 elsif ( defined $ENV{LOGDIR} && -f "$ENV{LOGDIR}/$rcfile" ) {
1466 safe_do("$ENV{LOGDIR}/$rcfile");
1469 # If the PERLDB_OPTS variable has options in it, parse those out next.
1470 if ( defined $ENV{PERLDB_OPTS} ) {
1471 parse_options( $ENV{PERLDB_OPTS} );
1476 The last thing we do during initialization is determine which subroutine is
1477 to be used to obtain a new terminal when a new debugger is started. Right now,
1478 the debugger only handles TCP sockets, X Windows, OS/2, amd Mac OS X
1483 # Set up the get_fork_TTY subroutine to be aliased to the proper routine.
1484 # Works if you're running an xterm or xterm-like window, or you're on
1485 # OS/2, or on Mac OS X. This may need some expansion.
1487 if (not defined &get_fork_TTY) # only if no routine exists
1489 if ( defined $remoteport ) {
1490 # Expect an inetd-like server
1491 *get_fork_TTY = \&socket_get_fork_TTY; # to listen to us
1493 elsif (defined $ENV{TERM} # If we know what kind
1494 # of terminal this is,
1495 and $ENV{TERM} eq 'xterm' # and it's an xterm,
1496 and defined $ENV{DISPLAY} # and what display it's on,
1499 *get_fork_TTY = \&xterm_get_fork_TTY; # use the xterm version
1501 elsif ( $^O eq 'os2' ) { # If this is OS/2,
1502 *get_fork_TTY = \&os2_get_fork_TTY; # use the OS/2 version
1504 elsif ( $^O eq 'darwin' # If this is Mac OS X
1505 and defined $ENV{TERM_PROGRAM} # and we're running inside
1506 and $ENV{TERM_PROGRAM}
1507 eq 'Apple_Terminal' # Terminal.app
1510 *get_fork_TTY = \&macosx_get_fork_TTY; # use the Mac OS X version
1512 } ## end if (not defined &get_fork_TTY...
1514 # untaint $^O, which may have been tainted by the last statement.
1515 # see bug [perl #24674]
1519 # Here begin the unreadable code. It needs fixing.
1521 =head2 RESTART PROCESSING
1523 This section handles the restart command. When the C<R> command is invoked, it
1524 tries to capture all of the state it can into environment variables, and
1525 then sets C<PERLDB_RESTART>. When we start executing again, we check to see
1526 if C<PERLDB_RESTART> is there; if so, we reload all the information that
1527 the R command stuffed into the environment variables.
1529 PERLDB_RESTART - flag only, contains no restart data itself.
1530 PERLDB_HIST - command history, if it's available
1531 PERLDB_ON_LOAD - breakpoints set by the rc file
1532 PERLDB_POSTPONE - subs that have been loaded/not executed, and have actions
1533 PERLDB_VISITED - files that had breakpoints
1534 PERLDB_FILE_... - breakpoints for a file
1535 PERLDB_OPT - active options
1536 PERLDB_INC - the original @INC
1537 PERLDB_PRETYPE - preprompt debugger actions
1538 PERLDB_PRE - preprompt Perl code
1539 PERLDB_POST - post-prompt Perl code
1540 PERLDB_TYPEAHEAD - typeahead captured by readline()
1542 We chug through all these variables and plug the values saved in them
1543 back into the appropriate spots in the debugger.
1547 if ( exists $ENV{PERLDB_RESTART} ) {
1549 # We're restarting, so we don't need the flag that says to restart anymore.
1550 delete $ENV{PERLDB_RESTART};
1553 @hist = get_list('PERLDB_HIST');
1554 %break_on_load = get_list("PERLDB_ON_LOAD");
1555 %postponed = get_list("PERLDB_POSTPONE");
1559 share(%break_on_load);
1562 # restore breakpoints/actions
1563 my @had_breakpoints = get_list("PERLDB_VISITED");
1564 for ( 0 .. $#had_breakpoints ) {
1565 my %pf = get_list("PERLDB_FILE_$_");
1566 $postponed_file{ $had_breakpoints[$_] } = \%pf if %pf;
1570 my %opt = get_list("PERLDB_OPT");
1572 while ( ( $opt, $val ) = each %opt ) {
1573 $val =~ s/[\\\']/\\$1/g;
1574 parse_options("$opt'$val'");
1577 # restore original @INC
1578 @INC = get_list("PERLDB_INC");
1581 # return pre/postprompt actions and typeahead buffer
1582 $pretype = [ get_list("PERLDB_PRETYPE") ];
1583 $pre = [ get_list("PERLDB_PRE") ];
1584 $post = [ get_list("PERLDB_POST") ];
1585 @typeahead = get_list( "PERLDB_TYPEAHEAD", @typeahead );
1586 } ## end if (exists $ENV{PERLDB_RESTART...
1588 =head2 SETTING UP THE TERMINAL
1590 Now, we'll decide how the debugger is going to interact with the user.
1591 If there's no TTY, we set the debugger to run non-stop; there's not going
1592 to be anyone there to enter commands.
1603 If there is a TTY, we have to determine who it belongs to before we can
1604 proceed. If this is a slave editor or graphical debugger (denoted by
1605 the first command-line switch being '-emacs'), we shift this off and
1606 set C<$rl> to 0 (XXX ostensibly to do straight reads).
1612 # Is Perl being run from a slave editor or graphical debugger?
1613 # If so, don't use readline, and set $slave_editor = 1.
1615 ( ( defined $main::ARGV[0] ) and ( $main::ARGV[0] eq '-emacs' ) );
1616 $rl = 0, shift(@main::ARGV) if $slave_editor;
1618 #require Term::ReadLine;
1622 We then determine what the console should be on various systems:
1626 =item * Cygwin - We use C<stdin> instead of a separate device.
1630 if ( $^O eq 'cygwin' ) {
1632 # /dev/tty is binary. use stdin for textmode
1636 =item * Unix - use C</dev/tty>.
1640 elsif ( -e "/dev/tty" ) {
1641 $console = "/dev/tty";
1644 =item * Windows or MSDOS - use C<con>.
1648 elsif ( $^O eq 'dos' or -e "con" or $^O eq 'MSWin32' ) {
1652 =item * VMS - use C<sys$command>.
1658 # everything else is ...
1659 $console = "sys\$command";
1666 Several other systems don't use a specific console. We C<undef $console>
1667 for those (Windows using a slave editor/graphical debugger, NetWare, OS/2
1668 with a slave editor, Epoc).
1672 if ( ( $^O eq 'MSWin32' ) and ( $slave_editor or defined $ENV{EMACS} ) ) {
1674 # /dev/tty is binary. use stdin for textmode
1678 if ( $^O eq 'NetWare' ) {
1680 # /dev/tty is binary. use stdin for textmode
1684 # In OS/2, we need to use STDIN to get textmode too, even though
1685 # it pretty much looks like Unix otherwise.
1686 if ( defined $ENV{OS2_SHELL} and ( $slave_editor or $ENV{WINDOWID} ) )
1691 # EPOC also falls into the 'got to use STDIN' camp.
1692 if ( $^O eq 'epoc' ) {
1698 If there is a TTY hanging around from a parent, we use that as the console.
1702 $console = $tty if defined $tty;
1704 =head2 SOCKET HANDLING
1706 The debugger is capable of opening a socket and carrying out a debugging
1707 session over the socket.
1709 If C<RemotePort> was defined in the options, the debugger assumes that it
1710 should try to start a debugging session on that port. It builds the socket
1711 and then tries to connect the input and output filehandles to it.
1715 # Handle socket stuff.
1717 if ( defined $remoteport ) {
1719 # If RemotePort was defined in the options, connect input and output
1721 $IN = $OUT = connect_remoteport();
1722 } ## end if (defined $remoteport)
1726 If no C<RemotePort> was defined, and we want to create a TTY on startup,
1727 this is probably a situation where multiple debuggers are running (for example,
1728 a backticked command that starts up another debugger). We create a new IN and
1729 OUT filehandle, and do the necessary mojo to create a new TTY if we know how
1737 # Two debuggers running (probably a system or a backtick that invokes
1738 # the debugger itself under the running one). create a new IN and OUT
1739 # filehandle, and do the necessary mojo to create a new tty if we
1740 # know how, and we can.
1741 create_IN_OUT(4) if $CreateTTY & 4;
1744 # If we have a console, check to see if there are separate ins and
1745 # outs to open. (They are assumed identical if not.)
1747 my ( $i, $o ) = split /,/, $console;
1748 $o = $i unless defined $o;
1750 # read/write on in, or just read, or read on STDIN.
1752 || open( IN, "<$i" )
1753 || open( IN, "<&STDIN" );
1755 # read/write/create/clobber out, or write/create/clobber out,
1756 # or merge with STDERR, or merge with STDOUT.
1758 || open( OUT, ">$o" )
1759 || open( OUT, ">&STDERR" )
1760 || open( OUT, ">&STDOUT" ); # so we don't dongle stdout
1762 } ## end if ($console)
1763 elsif ( not defined $console ) {
1765 # No console. Open STDIN.
1766 open( IN, "<&STDIN" );
1768 # merge with STDERR, or with STDOUT.
1769 open( OUT, ">&STDERR" )
1770 || open( OUT, ">&STDOUT" ); # so we don't dongle stdout
1771 $console = 'STDIN/OUT';
1772 } ## end elsif (not defined $console)
1774 # Keep copies of the filehandles so that when the pager runs, it
1775 # can close standard input without clobbering ours.
1776 $IN = \*IN, $OUT = \*OUT if $console or not defined $console;
1777 } ## end elsif (from if(defined $remoteport))
1779 # Unbuffer DB::OUT. We need to see responses right away.
1780 my $previous = select($OUT);
1781 $| = 1; # for DB::OUT
1784 # Line info goes to debugger output unless pointed elsewhere.
1785 # Pointing elsewhere makes it possible for slave editors to
1786 # keep track of file and position. We have both a filehandle
1787 # and a I/O description to keep track of.
1788 $LINEINFO = $OUT unless defined $LINEINFO;
1789 $lineinfo = $console unless defined $lineinfo;
1790 # share($LINEINFO); # <- unable to share globs
1795 To finish initialization, we show the debugger greeting,
1796 and then call the C<afterinit()> subroutine if there is one.
1800 # Show the debugger greeting.
1801 $header =~ s/.Header: ([^,]+),v(\s+\S+\s+\S+).*$/$1$2/;
1802 unless ($runnonstop) {
1805 if ( $term_pid eq '-1' ) {
1806 print $OUT "\nDaughter DB session started...\n";
1809 print $OUT "\nLoading DB routines from $header\n";
1812 $slave_editor ? "enabled" : "available", ".\n"
1815 "\nEnter h or `h h' for help, or `$doccmd perldebug' for more help.\n\n";
1816 } ## end else [ if ($term_pid eq '-1')
1817 } ## end unless ($runnonstop)
1818 } ## end else [ if ($notty)
1820 # XXX This looks like a bug to me.
1821 # Why copy to @ARGS and then futz with @args?
1824 # Make sure backslashes before single quotes are stripped out, and
1825 # keep args unless they are numeric (XXX why?)
1826 # s/\'/\\\'/g; # removed while not justified understandably
1827 # s/(.*)/'$1'/ unless /^-?[\d.]+$/; # ditto
1830 # If there was an afterinit() sub defined, call it. It will get
1831 # executed in our scope, so it can fiddle with debugger globals.
1832 if ( defined &afterinit ) { # May be defined in $rcfile
1836 # Inform us about "Stack dump during die enabled ..." in dieLevel().
1839 ############################################################ Subroutines
1845 This gigantic subroutine is the heart of the debugger. Called before every
1846 statement, its job is to determine if a breakpoint has been reached, and
1847 stop if so; read commands from the user, parse them, and execute
1848 them, and then send execution off to the next statement.
1850 Note that the order in which the commands are processed is very important;
1851 some commands earlier in the loop will actually alter the C<$cmd> variable
1852 to create other commands to be executed later. This is all highly I<optimized>
1853 but can be confusing. Check the comments for each C<$cmd ... && do {}> to
1854 see what's happening in any given command.
1860 # lock the debugger and get the thread id for the prompt
1863 if ($ENV{PERL5DB_THREADED}) {
1864 $tid = eval { "[".threads->tid."]" };
1867 # Check for whether we should be running continuously or not.
1868 # _After_ the perl program is compiled, $single is set to 1:
1869 if ( $single and not $second_time++ ) {
1871 # Options say run non-stop. Run until we get an interrupt.
1872 if ($runnonstop) { # Disable until signal
1873 # If there's any call stack in place, turn off single
1874 # stepping into subs throughout the stack.
1875 for ( $i = 0 ; $i <= $stack_depth ; ) {
1876 $stack[ $i++ ] &= ~1;
1879 # And we are now no longer in single-step mode.
1882 # If we simply returned at this point, we wouldn't get
1883 # the trace info. Fall on through.
1885 } ## end if ($runnonstop)
1887 elsif ($ImmediateStop) {
1889 # We are supposed to stop here; XXX probably a break.
1890 $ImmediateStop = 0; # We've processed it; turn it off
1891 $signal = 1; # Simulate an interrupt to force
1892 # us into the command loop
1894 } ## end if ($single and not $second_time...
1896 # If we're in single-step mode, or an interrupt (real or fake)
1897 # has occurred, turn off non-stop mode.
1898 $runnonstop = 0 if $single or $signal;
1900 # Preserve current values of $@, $!, $^E, $,, $/, $\, $^W.
1901 # The code being debugged may have altered them.
1904 # Since DB::DB gets called after every line, we can use caller() to
1905 # figure out where we last were executing. Sneaky, eh? This works because
1906 # caller is returning all the extra information when called from the
1908 local ( $package, $filename, $line ) = caller;
1909 local $filename_ini = $filename;
1911 # set up the context for DB::eval, so it can properly execute
1912 # code on behalf of the user. We add the package in so that the
1913 # code is eval'ed in the proper package (not in the debugger!).
1914 local $usercontext =
1915 '($@, $!, $^E, $,, $/, $\, $^W) = @saved;' . "package $package;";
1917 # Create an alias to the active file magical array to simplify
1919 local (*dbline) = $main::{ '_<' . $filename };
1921 # Last line in the program.
1922 local $max = $#dbline;
1924 # if we have something here, see if we should break.
1926 && ( ( $stop, $action ) = split( /\0/, $dbline{$line} ) ) )
1929 # Stop if the stop criterion says to just stop.
1930 if ( $stop eq '1' ) {
1934 # It's a conditional stop; eval it in the user's context and
1935 # see if we should stop. If so, remove the one-time sigil.
1937 $evalarg = "\$DB::signal |= 1 if do {$stop}";
1939 $dbline{$line} =~ s/;9($|\0)/$1/;
1941 } ## end if ($dbline{$line} && ...
1943 # Preserve the current stop-or-not, and see if any of the W
1944 # (watch expressions) has changed.
1945 my $was_signal = $signal;
1947 # If we have any watch expressions ...
1949 for ( my $n = 0 ; $n <= $#to_watch ; $n++ ) {
1950 $evalarg = $to_watch[$n];
1951 local $onetimeDump; # Tell DB::eval() to not output results
1953 # Fix context DB::eval() wants to return an array, but
1954 # we need a scalar here.
1955 my ($val) = join( "', '", &eval );
1956 $val = ( ( defined $val ) ? "'$val'" : 'undef' );
1959 if ( $val ne $old_watch[$n] ) {
1961 # Yep! Show the difference, and fake an interrupt.
1964 Watchpoint $n:\t$to_watch[$n] changed:
1965 old value:\t$old_watch[$n]
1968 $old_watch[$n] = $val;
1969 } ## end if ($val ne $old_watch...
1970 } ## end for (my $n = 0 ; $n <= ...
1971 } ## end if ($trace & 2)
1973 =head2 C<watchfunction()>
1975 C<watchfunction()> is a function that can be defined by the user; it is a
1976 function which will be run on each entry to C<DB::DB>; it gets the
1977 current package, filename, and line as its parameters.
1979 The watchfunction can do anything it likes; it is executing in the
1980 debugger's context, so it has access to all of the debugger's internal
1981 data structures and functions.
1983 C<watchfunction()> can control the debugger's actions. Any of the following
1984 will cause the debugger to return control to the user's program after
1985 C<watchfunction()> executes:
1991 Returning a false value from the C<watchfunction()> itself.
1995 Altering C<$single> to a false value.
1999 Altering C<$signal> to a false value.
2003 Turning off the C<4> bit in C<$trace> (this also disables the
2004 check for C<watchfunction()>. This can be done with
2012 # If there's a user-defined DB::watchfunction, call it with the
2013 # current package, filename, and line. The function executes in
2015 if ( $trace & 4 ) { # User-installed watch
2017 if watchfunction( $package, $filename, $line )
2020 and not( $trace & ~4 );
2021 } ## end if ($trace & 4)
2023 # Pick up any alteration to $signal in the watchfunction, and
2024 # turn off the signal now.
2025 $was_signal = $signal;
2028 =head2 GETTING READY TO EXECUTE COMMANDS
2030 The debugger decides to take control if single-step mode is on, the
2031 C<t> command was entered, or the user generated a signal. If the program
2032 has fallen off the end, we set things up so that entering further commands
2033 won't cause trouble, and we say that the program is over.
2037 # Check to see if we should grab control ($single true,
2038 # trace set appropriately, or we got a signal).
2039 if ( $single || ( $trace & 1 ) || $was_signal ) {
2041 # Yes, grab control.
2042 if ($slave_editor) {
2044 # Tell the editor to update its position.
2045 $position = "\032\032$filename:$line:0\n";
2046 print_lineinfo($position);
2051 Special check: if we're in package C<DB::fake>, we've gone through the
2052 C<END> block at least once. We set up everything so that we can continue
2053 to enter commands and have a valid context to be in.
2057 elsif ( $package eq 'DB::fake' ) {
2059 # Fallen off the end already.
2062 Debugged program terminated. Use B<q> to quit or B<R> to restart,
2063 use B<o> I<inhibit_exit> to avoid stopping after program termination,
2064 B<h q>, B<h R> or B<h o> to get additional info.
2067 # Set the DB::eval context appropriately.
2070 '($@, $!, $^E, $,, $/, $\, $^W) = @saved;'
2071 . "package $package;"; # this won't let them modify, alas
2072 } ## end elsif ($package eq 'DB::fake')
2076 If the program hasn't finished executing, we scan forward to the
2077 next executable line, print that out, build the prompt from the file and line
2078 number information, and print that.
2084 # Still somewhere in the midst of execution. Set up the
2086 $sub =~ s/\'/::/; # Swap Perl 4 package separators (') to
2087 # Perl 5 ones (sorry, we don't print Klingon
2090 $prefix = $sub =~ /::/ ? "" : "${'package'}::";
2091 $prefix .= "$sub($filename:";
2092 $after = ( $dbline[$line] =~ /\n$/ ? '' : "\n" );
2094 # Break up the prompt if it's really long.
2095 if ( length($prefix) > 30 ) {
2096 $position = "$prefix$line):\n$line:\t$dbline[$line]$after";
2102 $position = "$prefix$line$infix$dbline[$line]$after";
2105 # Print current line info, indenting if necessary.
2107 print_lineinfo( ' ' x $stack_depth,
2108 "$line:\t$dbline[$line]$after" );
2111 print_lineinfo($position);
2114 # Scan forward, stopping at either the end or the next
2116 for ( $i = $line + 1 ; $i <= $max && $dbline[$i] == 0 ; ++$i )
2119 # Drop out on null statements, block closers, and comments.
2120 last if $dbline[$i] =~ /^\s*[\;\}\#\n]/;
2122 # Drop out if the user interrupted us.
2125 # Append a newline if the line doesn't have one. Can happen
2126 # in eval'ed text, for instance.
2127 $after = ( $dbline[$i] =~ /\n$/ ? '' : "\n" );
2129 # Next executable line.
2130 $incr_pos = "$prefix$i$infix$dbline[$i]$after";
2131 $position .= $incr_pos;
2134 # Print it indented if tracing is on.
2135 print_lineinfo( ' ' x $stack_depth,
2136 "$i:\t$dbline[$i]$after" );
2139 print_lineinfo($incr_pos);
2141 } ## end for ($i = $line + 1 ; $i...
2142 } ## end else [ if ($slave_editor)
2143 } ## end if ($single || ($trace...
2147 If there's an action to be executed for the line we stopped at, execute it.
2148 If there are any preprompt actions, execute those as well.
2152 # If there's an action, do it now.
2153 $evalarg = $action, &eval if $action;
2155 # Are we nested another level (e.g., did we evaluate a function
2156 # that had a breakpoint in it at the debugger prompt)?
2157 if ( $single || $was_signal ) {
2159 # Yes, go down a level.
2160 local $level = $level + 1;
2162 # Do any pre-prompt actions.
2163 foreach $evalarg (@$pre) {
2167 # Complain about too much recursion if we passed the limit.
2168 print $OUT $stack_depth . " levels deep in subroutine calls!\n"
2171 # The line we're currently on. Set $incr to -1 to stay here
2172 # until we get a command that tells us to advance.
2174 $incr = -1; # for backward motion.
2176 # Tack preprompt debugger actions ahead of any actual input.
2177 @typeahead = ( @$pretype, @typeahead );
2179 =head2 WHERE ARE WE?
2181 XXX Relocate this section?
2183 The debugger normally shows the line corresponding to the current line of
2184 execution. Sometimes, though, we want to see the next line, or to move elsewhere
2185 in the file. This is done via the C<$incr>, C<$start>, and C<$max> variables.
2187 C<$incr> controls by how many lines the I<current> line should move forward
2188 after a command is executed. If set to -1, this indicates that the I<current>
2189 line shouldn't change.
2191 C<$start> is the I<current> line. It is used for things like knowing where to
2192 move forwards or backwards from when doing an C<L> or C<-> command.
2194 C<$max> tells the debugger where the last line of the current file is. It's
2195 used to terminate loops most often.
2197 =head2 THE COMMAND LOOP
2199 Most of C<DB::DB> is actually a command parsing and dispatch loop. It comes
2206 The outer part of the loop, starting at the C<CMD> label. This loop
2207 reads a command and then executes it.
2211 The inner part of the loop, starting at the C<PIPE> label. This part
2212 is wholly contained inside the C<CMD> block and only executes a command.
2213 Used to handle commands running inside a pager.
2217 So why have two labels to restart the loop? Because sometimes, it's easier to
2218 have a command I<generate> another command and then re-execute the loop to do
2219 the new command. This is faster, but perhaps a bit more convoluted.
2223 # The big command dispatch loop. It keeps running until the
2224 # user yields up control again.
2226 # If we have a terminal for input, and we get something back
2227 # from readline(), keep on processing.
2231 # We have a terminal, or can get one ...
2232 ( $term || &setterm ),
2234 # ... and it belogs to this PID or we get one for this PID ...
2235 ( $term_pid == $$ or resetterm(1) ),
2237 # ... and we got a line of command input ...
2240 "$pidprompt $tid DB"
2243 . ( '>' x $level ) . " "
2250 # ... try to execute the input as debugger commands.
2252 # Don't stop running.
2255 # No signal is active.
2258 # Handle continued commands (ending with \):
2259 $cmd =~ s/\\$/\n/ && do {
2260 $cmd .= &readline(" cont: ");
2264 =head4 The null command
2266 A newline entered by itself means I<re-execute the last command>. We grab the
2267 command out of C<$laststep> (where it was recorded previously), and copy it
2268 back into C<$cmd> to be executed below. If there wasn't any previous command,
2269 we'll do nothing below (no command will match). If there was, we also save it
2270 in the command history and fall through to allow the command parsing to pick
2275 # Empty input means repeat the last command.
2276 $cmd =~ /^$/ && ( $cmd = $laststep );
2277 chomp($cmd); # get rid of the annoying extra newline
2278 push( @hist, $cmd ) if length($cmd) > 1;
2279 push( @truehist, $cmd );
2283 # This is a restart point for commands that didn't arrive
2284 # via direct user input. It allows us to 'redo PIPE' to
2285 # re-execute command processing without reading a new command.
2287 $cmd =~ s/^\s+//s; # trim annoying leading whitespace
2288 $cmd =~ s/\s+$//s; # trim annoying trailing whitespace
2289 ($i) = split( /\s+/, $cmd );
2291 =head3 COMMAND ALIASES
2293 The debugger can create aliases for commands (these are stored in the
2294 C<%alias> hash). Before a command is executed, the command loop looks it up
2295 in the alias hash and substitutes the contents of the alias for the command,
2296 completely replacing it.
2300 # See if there's an alias for the command, and set it up if so.
2303 # Squelch signal handling; we want to keep control here
2304 # if something goes loco during the alias eval.
2305 local $SIG{__DIE__};
2306 local $SIG{__WARN__};
2308 # This is a command, so we eval it in the DEBUGGER's
2309 # scope! Otherwise, we can't see the special debugger
2310 # variables, or get to the debugger's subs. (Well, we
2311 # _could_, but why make it even more complicated?)
2312 eval "\$cmd =~ $alias{$i}";
2315 print $OUT "Couldn't evaluate `$i' alias: $@";
2318 } ## end if ($alias{$i})
2320 =head3 MAIN-LINE COMMANDS
2322 All of these commands work up to and after the program being debugged has
2327 Quit the debugger. This entails setting the C<$fall_off_end> flag, so we don't
2328 try to execute further, cleaning any restart-related stuff out of the
2329 environment, and executing with the last value of C<$?>.
2333 $cmd =~ /^q$/ && do {
2341 Turn tracing on or off. Inverts the appropriate bit in C<$trace> (q.v.).
2345 $cmd =~ /^t$/ && do {
2348 print $OUT "Trace = "
2349 . ( ( $trace & 1 ) ? "on" : "off" ) . "\n";
2353 =head4 C<S> - list subroutines matching/not matching a pattern
2355 Walks through C<%sub>, checking to see whether or not to print the name.
2359 $cmd =~ /^S(\s+(!)?(.+))?$/ && do {
2361 $Srev = defined $2; # Reverse scan?
2362 $Spatt = $3; # The pattern (if any) to use.
2363 $Snocheck = !defined $1; # No args - print all subs.
2365 # Need to make these sane here.
2369 # Search through the debugger's magical hash of subs.
2370 # If $nocheck is true, just print the sub name.
2371 # Otherwise, check it against the pattern. We then use
2372 # the XOR trick to reverse the condition as required.
2373 foreach $subname ( sort( keys %sub ) ) {
2374 if ( $Snocheck or $Srev ^ ( $subname =~ /$Spatt/ ) ) {
2375 print $OUT $subname, "\n";
2381 =head4 C<X> - list variables in current package
2383 Since the C<V> command actually processes this, just change this to the
2384 appropriate C<V> command and fall through.
2388 $cmd =~ s/^X\b/V $package/;
2390 =head4 C<V> - list variables
2392 Uses C<dumpvar.pl> to dump out the current values for selected variables.
2396 # Bare V commands get the currently-being-debugged package
2398 $cmd =~ /^V$/ && do {
2399 $cmd = "V $package";
2402 # V - show variables in package.
2403 $cmd =~ /^V\b\s*(\S+)\s*(.*)/ && do {
2405 # Save the currently selected filehandle and
2406 # force output to debugger's filehandle (dumpvar
2407 # just does "print" for output).
2408 local ($savout) = select($OUT);
2410 # Grab package name and variables to dump.
2412 @vars = split( ' ', $2 );
2414 # If main::dumpvar isn't here, get it.
2415 do 'dumpvar.pl' || die $@ unless defined &main::dumpvar;
2416 if ( defined &main::dumpvar ) {
2418 # We got it. Turn off subroutine entry/exit messages
2419 # for the moment, along with return values.
2423 # must detect sigpipe failures - not catching
2424 # then will cause the debugger to die.
2428 defined $option{dumpDepth}
2429 ? $option{dumpDepth}
2430 : -1, # assume -1 unless specified
2435 # The die doesn't need to include the $@, because
2436 # it will automatically get propagated for us.
2438 die unless $@ =~ /dumpvar print failed/;
2440 } ## end if (defined &main::dumpvar)
2443 # Couldn't load dumpvar.
2444 print $OUT "dumpvar.pl not available.\n";
2447 # Restore the output filehandle, and go round again.
2452 =head4 C<x> - evaluate and print an expression
2454 Hands the expression off to C<DB::eval>, setting it up to print the value
2455 via C<dumpvar.pl> instead of just printing it directly.
2459 $cmd =~ s/^x\b/ / && do { # Remainder gets done by DB::eval()
2460 $onetimeDump = 'dump'; # main::dumpvar shows the output
2462 # handle special "x 3 blah" syntax XXX propagate
2463 # doc back to special variables.
2464 if ( $cmd =~ s/^\s*(\d+)(?=\s)/ / ) {
2465 $onetimedumpDepth = $1;
2469 =head4 C<m> - print methods
2471 Just uses C<DB::methods> to determine what methods are available.
2475 $cmd =~ s/^m\s+([\w:]+)\s*$/ / && do {
2480 # m expr - set up DB::eval to do the work
2481 $cmd =~ s/^m\b/ / && do { # Rest gets done by DB::eval()
2482 $onetimeDump = 'methods'; # method output gets used there
2485 =head4 C<f> - switch files
2489 $cmd =~ /^f\b\s*(.*)/ && do {
2493 # help for no arguments (old-style was return from sub).
2496 "The old f command is now the r command.\n"; # hint
2497 print $OUT "The new f command switches filenames.\n";
2499 } ## end if (!$file)
2501 # if not in magic file list, try a close match.
2502 if ( !defined $main::{ '_<' . $file } ) {
2503 if ( ($try) = grep( m#^_<.*$file#, keys %main:: ) ) {
2505 $try = substr( $try, 2 );
2506 print $OUT "Choosing $try matching `$file':\n";
2509 } ## end if (($try) = grep(m#^_<.*$file#...
2510 } ## end if (!defined $main::{ ...
2512 # If not successfully switched now, we failed.
2513 if ( !defined $main::{ '_<' . $file } ) {
2514 print $OUT "No file matching `$file' is loaded.\n";
2518 # We switched, so switch the debugger internals around.
2519 elsif ( $file ne $filename ) {
2520 *dbline = $main::{ '_<' . $file };
2525 } ## end elsif ($file ne $filename)
2527 # We didn't switch; say we didn't.
2529 print $OUT "Already in $file.\n";
2534 =head4 C<.> - return to last-executed line.
2536 We set C<$incr> to -1 to indicate that the debugger shouldn't move ahead,
2537 and then we look up the line in the magical C<%dbline> hash.
2542 $cmd =~ /^\.$/ && do {
2543 $incr = -1; # stay at current line
2545 # Reset everything to the old location.
2547 $filename = $filename_ini;
2548 *dbline = $main::{ '_<' . $filename };
2552 print_lineinfo($position);
2556 =head4 C<-> - back one window
2558 We change C<$start> to be one window back; if we go back past the first line,
2559 we set it to be the first line. We ser C<$incr> to put us back at the
2560 currently-executing line, and then put a C<l $start +> (list one window from
2561 C<$start>) in C<$cmd> to be executed later.
2565 # - - back a window.
2566 $cmd =~ /^-$/ && do {
2568 # back up by a window; go to 1 if back too far.
2569 $start -= $incr + $window + 1;
2570 $start = 1 if $start <= 0;
2571 $incr = $window - 1;
2573 # Generate and execute a "l +" command (handled below).
2574 $cmd = 'l ' . ($start) . '+';
2577 =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>, {, {{>
2579 In Perl 5.8.0, a realignment of the commands was done to fix up a number of
2580 problems, most notably that the default case of several commands destroying
2581 the user's work in setting watchpoints, actions, etc. We wanted, however, to
2582 retain the old commands for those who were used to using them or who preferred
2583 them. At this point, we check for the new commands and call C<cmd_wrapper> to
2584 deal with them instead of processing them in-line.
2588 # All of these commands were remapped in perl 5.8.0;
2589 # we send them off to the secondary dispatcher (see below).
2590 $cmd =~ /^([aAbBeEhilLMoOPvwW]\b|[<>\{]{1,2})\s*(.*)/so && do {
2591 &cmd_wrapper( $1, $2, $line );
2595 =head4 C<y> - List lexicals in higher scope
2597 Uses C<PadWalker> to find the lexicals supplied as arguments in a scope
2598 above the current one and then displays then using C<dumpvar.pl>.
2602 $cmd =~ /^y(?:\s+(\d*)\s*(.*))?$/ && do {
2604 # See if we've got the necessary support.
2605 eval { require PadWalker; PadWalker->VERSION(0.08) }
2608 ? "PadWalker module not found - please install\n"
2613 # Load up dumpvar if we don't have it. If we can, that is.
2614 do 'dumpvar.pl' || die $@ unless defined &main::dumpvar;
2615 defined &main::dumpvar
2616 or print $OUT "dumpvar.pl not available.\n"
2619 # Got all the modules we need. Find them and print them.
2620 my @vars = split( ' ', $2 || '' );
2623 my $h = eval { PadWalker::peek_my( ( $1 || 0 ) + 1 ) };
2625 # Oops. Can't find it.
2626 $@ and $@ =~ s/ at .*//, &warn($@), next CMD;
2628 # Show the desired vars with dumplex().
2629 my $savout = select($OUT);
2631 # Have dumplex dump the lexicals.
2632 dumpvar::dumplex( $_, $h->{$_},
2633 defined $option{dumpDepth} ? $option{dumpDepth} : -1,
2640 =head3 COMMANDS NOT WORKING AFTER PROGRAM ENDS
2642 All of the commands below this point don't work after the program being
2643 debugged has ended. All of them check to see if the program has ended; this
2644 allows the commands to be relocated without worrying about a 'line of
2645 demarcation' above which commands can be entered anytime, and below which
2648 =head4 C<n> - single step, but don't trace down into subs
2650 Done by setting C<$single> to 2, which forces subs to execute straight through
2651 when entered (see C<DB::sub>). We also save the C<n> command in C<$laststep>,
2652 so a null command knows what to re-execute.
2657 $cmd =~ /^n$/ && do {
2658 end_report(), next CMD if $finished and $level <= 1;
2660 # Single step, but don't enter subs.
2663 # Save for empty command (repeat last).
2668 =head4 C<s> - single-step, entering subs
2670 Sets C<$single> to 1, which causes C<DB::sub> to continue tracing inside
2671 subs. Also saves C<s> as C<$lastcmd>.
2676 $cmd =~ /^s$/ && do {
2678 # Get out and restart the command loop if program
2680 end_report(), next CMD if $finished and $level <= 1;
2682 # Single step should enter subs.
2685 # Save for empty command (repeat last).
2690 =head4 C<c> - run continuously, setting an optional breakpoint
2692 Most of the code for this command is taken up with locating the optional
2693 breakpoint, which is either a subroutine name or a line number. We set
2694 the appropriate one-time-break in C<@dbline> and then turn off single-stepping
2695 in this and all call levels above this one.
2699 # c - start continuous execution.
2700 $cmd =~ /^c\b\s*([\w:]*)\s*$/ && do {
2702 # Hey, show's over. The debugged program finished
2703 # executing already.
2704 end_report(), next CMD if $finished and $level <= 1;
2706 # Capture the place to put a one-time break.
2709 # Probably not needed, since we finish an interactive
2710 # sub-session anyway...
2711 # local $filename = $filename;
2712 # local *dbline = *dbline; # XXX Would this work?!
2714 # The above question wonders if localizing the alias
2715 # to the magic array works or not. Since it's commented
2716 # out, we'll just leave that to speculation for now.
2718 # If the "subname" isn't all digits, we'll assume it
2719 # is a subroutine name, and try to find it.
2720 if ( $subname =~ /\D/ ) { # subroutine name
2721 # Qualify it to the current package unless it's
2722 # already qualified.
2723 $subname = $package . "::" . $subname
2724 unless $subname =~ /::/;
2726 # find_sub will return "file:line_number" corresponding
2727 # to where the subroutine is defined; we call find_sub,
2728 # break up the return value, and assign it in one
2730 ( $file, $i ) = ( find_sub($subname) =~ /^(.*):(.*)$/ );
2732 # Force the line number to be numeric.
2735 # If we got a line number, we found the sub.
2738 # Switch all the debugger's internals around so
2739 # we're actually working with that file.
2741 *dbline = $main::{ '_<' . $filename };
2743 # Mark that there's a breakpoint in this file.
2744 $had_breakpoints{$filename} |= 1;
2746 # Scan forward to the first executable line
2747 # after the 'sub whatever' line.
2749 ++$i while $dbline[$i] == 0 && $i < $max;
2752 # We didn't find a sub by that name.
2754 print $OUT "Subroutine $subname not found.\n";
2757 } ## end if ($subname =~ /\D/)
2759 # At this point, either the subname was all digits (an
2760 # absolute line-break request) or we've scanned through
2761 # the code following the definition of the sub, looking
2762 # for an executable, which we may or may not have found.
2764 # If $i (which we set $subname from) is non-zero, we
2765 # got a request to break at some line somewhere. On
2766 # one hand, if there wasn't any real subroutine name
2767 # involved, this will be a request to break in the current
2768 # file at the specified line, so we have to check to make
2769 # sure that the line specified really is breakable.
2771 # On the other hand, if there was a subname supplied, the
2772 # preceding block has moved us to the proper file and
2773 # location within that file, and then scanned forward
2774 # looking for the next executable line. We have to make
2775 # sure that one was found.
2777 # On the gripping hand, we can't do anything unless the
2778 # current value of $i points to a valid breakable line.
2783 if ( $dbline[$i] == 0 ) {
2784 print $OUT "Line $i not breakable.\n";
2788 # Yes. Set up the one-time-break sigil.
2789 $dbline{$i} =~ s/($|\0)/;9$1/; # add one-time-only b.p.
2792 # Turn off stack tracing from here up.
2793 for ( $i = 0 ; $i <= $stack_depth ; ) {
2794 $stack[ $i++ ] &= ~1;
2799 =head4 C<r> - return from a subroutine
2801 For C<r> to work properly, the debugger has to stop execution again
2802 immediately after the return is executed. This is done by forcing
2803 single-stepping to be on in the call level above the current one. If
2804 we are printing return values when a C<r> is executed, set C<$doret>
2805 appropriately, and force us out of the command loop.
2809 # r - return from the current subroutine.
2810 $cmd =~ /^r$/ && do {
2812 # Can't do anythign if the program's over.
2813 end_report(), next CMD if $finished and $level <= 1;
2815 # Turn on stack trace.
2816 $stack[$stack_depth] |= 1;
2818 # Print return value unless the stack is empty.
2819 $doret = $option{PrintRet} ? $stack_depth - 1 : -2;
2823 =head4 C<T> - stack trace
2825 Just calls C<DB::print_trace>.
2829 $cmd =~ /^T$/ && do {
2830 print_trace( $OUT, 1 ); # skip DB
2834 =head4 C<w> - List window around current line.
2836 Just calls C<DB::cmd_w>.
2840 $cmd =~ /^w\b\s*(.*)/s && do { &cmd_w( 'w', $1 ); next CMD; };
2842 =head4 C<W> - watch-expression processing.
2844 Just calls C<DB::cmd_W>.
2848 $cmd =~ /^W\b\s*(.*)/s && do { &cmd_W( 'W', $1 ); next CMD; };
2850 =head4 C</> - search forward for a string in the source
2852 We take the argument and treat it as a pattern. If it turns out to be a
2853 bad one, we return the error we got from trying to C<eval> it and exit.
2854 If not, we create some code to do the search and C<eval> it so it can't
2859 $cmd =~ /^\/(.*)$/ && do {
2861 # The pattern as a string.
2864 # Remove the final slash.
2865 $inpat =~ s:([^\\])/$:$1:;
2867 # If the pattern isn't null ...
2868 if ( $inpat ne "" ) {
2870 # Turn of warn and die procesing for a bit.
2871 local $SIG{__DIE__};
2872 local $SIG{__WARN__};
2874 # Create the pattern.
2875 eval '$inpat =~ m' . "\a$inpat\a";
2878 # Oops. Bad pattern. No biscuit.
2879 # Print the eval error and go back for more
2885 } ## end if ($inpat ne "")
2887 # Set up to stop on wrap-around.
2890 # Don't move off the current line.
2893 # Done in eval so nothing breaks if the pattern
2894 # does something weird.
2897 # Move ahead one line.
2900 # Wrap if we pass the last line.
2901 $start = 1 if ($start > $max);
2903 # Stop if we have gotten back to this line again,
2904 last if ($start == $end);
2906 # A hit! (Note, though, that we are doing
2907 # case-insensitive matching. Maybe a qr//
2908 # expression would be better, so the user could
2909 # do case-sensitive matching if desired.
2910 if ($dbline[$start] =~ m' . "\a$pat\a" . 'i) {
2911 if ($slave_editor) {
2912 # Handle proper escaping in the slave.
2913 print $OUT "\032\032$filename:$start:0\n";
2916 # Just print the line normally.
2917 print $OUT "$start:\t",$dbline[$start],"\n";
2919 # And quit since we found something.
2924 # If we wrapped, there never was a match.
2925 print $OUT "/$pat/: not found\n" if ( $start == $end );
2929 =head4 C<?> - search backward for a string in the source
2931 Same as for C</>, except the loop runs backwards.
2935 # ? - backward pattern search.
2936 $cmd =~ /^\?(.*)$/ && do {
2938 # Get the pattern, remove trailing question mark.
2940 $inpat =~ s:([^\\])\?$:$1:;
2942 # If we've got one ...
2943 if ( $inpat ne "" ) {
2945 # Turn off die & warn handlers.
2946 local $SIG{__DIE__};
2947 local $SIG{__WARN__};
2948 eval '$inpat =~ m' . "\a$inpat\a";
2952 # Ouch. Not good. Print the error.
2957 } ## end if ($inpat ne "")
2959 # Where we are now is where to stop after wraparound.
2962 # Don't move away from this line.
2965 # Search inside the eval to prevent pattern badness
2972 # Wrap if we pass the first line.
2974 $start = $max if ($start <= 0);
2976 # Quit if we get back where we started,
2977 last if ($start == $end);
2980 if ($dbline[$start] =~ m' . "\a$pat\a" . 'i) {
2981 if ($slave_editor) {
2982 # Yep, follow slave editor requirements.
2983 print $OUT "\032\032$filename:$start:0\n";
2986 # Yep, just print normally.
2987 print $OUT "$start:\t",$dbline[$start],"\n";
2995 # Say we failed if the loop never found anything,
2996 print $OUT "?$pat?: not found\n" if ( $start == $end );
3000 =head4 C<$rc> - Recall command
3002 Manages the commands in C<@hist> (which is created if C<Term::ReadLine> reports
3003 that the terminal supports history). It find the the command required, puts it
3004 into C<$cmd>, and redoes the loop to execute it.
3008 # $rc - recall command.
3009 $cmd =~ /^$rc+\s*(-)?(\d+)?$/ && do {
3011 # No arguments, take one thing off history.
3012 pop(@hist) if length($cmd) > 1;
3014 # Relative (- found)?
3015 # Y - index back from most recent (by 1 if bare minus)
3016 # N - go to that particular command slot or the last
3017 # thing if nothing following.
3018 $i = $1 ? ( $#hist - ( $2 || 1 ) ) : ( $2 || $#hist );
3020 # Pick out the command desired.
3023 # Print the command to be executed and restart the loop
3024 # with that command in the buffer.
3025 print $OUT $cmd, "\n";
3029 =head4 C<$sh$sh> - C<system()> command
3031 Calls the C<DB::system()> to handle the command. This keeps the C<STDIN> and
3032 C<STDOUT> from getting messed up.
3036 # $sh$sh - run a shell command (if it's all ASCII).
3037 # Can't run shell commands with Unicode in the debugger, hmm.
3038 $cmd =~ /^$sh$sh\s*([\x00-\xff]*)/ && do {
3045 =head4 C<$rc I<pattern> $rc> - Search command history
3047 Another command to manipulate C<@hist>: this one searches it with a pattern.
3048 If a command is found, it is placed in C<$cmd> and executed via C<redo>.
3052 # $rc pattern $rc - find a command in the history.
3053 $cmd =~ /^$rc([^$rc].*)$/ && do {
3055 # Create the pattern to use.
3058 # Toss off last entry if length is >1 (and it always is).
3059 pop(@hist) if length($cmd) > 1;
3061 # Look backward through the history.
3062 for ( $i = $#hist ; $i ; --$i ) {
3064 # Stop if we find it.
3065 last if $hist[$i] =~ /$pat/;
3071 print $OUT "No such command!\n\n";
3075 # Found it. Put it in the buffer, print it, and process it.
3077 print $OUT $cmd, "\n";
3081 =head4 C<$sh> - Invoke a shell
3083 Uses C<DB::system> to invoke a shell.
3087 # $sh - start a shell.
3088 $cmd =~ /^$sh$/ && do {
3090 # Run the user's shell. If none defined, run Bourne.
3091 # We resume execution when the shell terminates.
3092 &system( $ENV{SHELL} || "/bin/sh" );
3096 =head4 C<$sh I<command>> - Force execution of a command in a shell
3098 Like the above, but the command is passed to the shell. Again, we use
3099 C<DB::system> to avoid problems with C<STDIN> and C<STDOUT>.
3103 # $sh command - start a shell and run a command in it.
3104 $cmd =~ /^$sh\s*([\x00-\xff]*)/ && do {
3106 # XXX: using csh or tcsh destroys sigint retvals!
3107 #&system($1); # use this instead
3109 # use the user's shell, or Bourne if none defined.
3110 &system( $ENV{SHELL} || "/bin/sh", "-c", $1 );
3114 =head4 C<H> - display commands in history
3116 Prints the contents of C<@hist> (if any).
3120 $cmd =~ /^H\b\s*\*/ && do {
3121 @hist = @truehist = ();
3122 print $OUT "History cleansed\n";
3126 $cmd =~ /^H\b\s*(-(\d+))?/ && do {
3128 # Anything other than negative numbers is ignored by
3129 # the (incorrect) pattern, so this test does nothing.
3130 $end = $2 ? ( $#hist - $2 ) : 0;
3132 # Set to the minimum if less than zero.
3133 $hist = 0 if $hist < 0;
3135 # Start at the end of the array.
3136 # Stay in while we're still above the ending value.
3137 # Tick back by one each time around the loop.
3138 for ( $i = $#hist ; $i > $end ; $i-- ) {
3140 # Print the command unless it has no arguments.
3141 print $OUT "$i: ", $hist[$i], "\n"
3142 unless $hist[$i] =~ /^.?$/;
3147 =head4 C<man, doc, perldoc> - look up documentation
3149 Just calls C<runman()> to print the appropriate document.
3153 # man, perldoc, doc - show manual pages.
3154 $cmd =~ /^(?:man|(?:perl)?doc)\b(?:\s+([^(]*))?$/ && do {
3161 Builds a C<print EXPR> expression in the C<$cmd>; this will get executed at
3162 the bottom of the loop.
3166 # p - print (no args): print $_.
3167 $cmd =~ s/^p$/print {\$DB::OUT} \$_/;
3169 # p - print the given expression.
3170 $cmd =~ s/^p\b/print {\$DB::OUT} /;
3172 =head4 C<=> - define command alias
3174 Manipulates C<%alias> to add or list command aliases.
3178 # = - set up a command alias.
3179 $cmd =~ s/^=\s*// && do {
3181 if ( length $cmd == 0 ) {
3183 # No args, get current aliases.
3184 @keys = sort keys %alias;
3186 elsif ( my ( $k, $v ) = ( $cmd =~ /^(\S+)\s+(\S.*)/ ) ) {
3188 # Creating a new alias. $k is alias name, $v is
3191 # can't use $_ or kill //g state
3192 for my $x ( $k, $v ) {
3194 # Escape "alarm" characters.
3198 # Substitute key for value, using alarm chars
3199 # as separators (which is why we escaped them in
3201 $alias{$k} = "s\a$k\a$v\a";
3203 # Turn off standard warn and die behavior.
3204 local $SIG{__DIE__};
3205 local $SIG{__WARN__};
3208 unless ( eval "sub { s\a$k\a$v\a }; 1" ) {
3210 # Nope. Bad alias. Say so and get out.
3211 print $OUT "Can't alias $k to $v: $@\n";
3216 # We'll only list the new one.
3218 } ## end elsif (my ($k, $v) = ($cmd...
3220 # The argument is the alias to list.
3228 # Messy metaquoting: Trim the substiution code off.
3229 # We use control-G as the delimiter because it's not
3230 # likely to appear in the alias.
3231 if ( ( my $v = $alias{$k} ) =~ s
\as\a$k\a(.*)\a$
\a1
\a ) {
3234 print $OUT "$k\t= $1\n";
3236 elsif ( defined $alias{$k} ) {
3238 # Couldn't trim it off; just print the alias code.
3239 print $OUT "$k\t$alias{$k}\n";
3244 print "No alias for $k\n";
3246 } ## end for my $k (@keys)
3250 =head4 C<source> - read commands from a file.
3252 Opens a lexical filehandle and stacks it on C<@cmdfhs>; C<DB::readline> will
3257 # source - read commands from a file (or pipe!) and execute.
3258 $cmd =~ /^source\s+(.*\S)/ && do {
3259 if ( open my $fh, $1 ) {
3261 # Opened OK; stick it in the list of file handles.
3267 &warn("Can't execute `$1': $!\n");
3272 =head4 C<save> - send current history to a file
3274 Takes the complete history, (not the shrunken version you see with C<H>),
3275 and saves it to the given filename, so it can be replayed using C<source>.
3277 Note that all C<^(save|source)>'s are commented out with a view to minimise recursion.
3281 # save source - write commands to a file for later use
3282 $cmd =~ /^save\s*(.*)$/ && do {
3283 my $file = $1 || '.perl5dbrc'; # default?
3284 if ( open my $fh, "> $file" ) {
3286 # chomp to remove extraneous newlines from source'd files
3287 chomp( my @truelist =
3288 map { m/^\s*(save|source)/ ? "#$_" : $_ }
3290 print $fh join( "\n", @truelist );
3291 print "commands saved in $file\n";
3294 &warn("Can't save debugger commands in '$1': $!\n");
3299 =head4 C<R> - restart
3301 Restart the debugger session.
3303 =head4 C<rerun> - rerun the current session
3305 Return to any given position in the B<true>-history list
3309 # R - restart execution.
3310 # rerun - controlled restart execution.
3311 $cmd =~ /^(R|rerun\s*(.*))$/ && do {
3312 my @args = ($1 eq 'R' ? restart() : rerun($2));
3314 # Close all non-system fds for a clean restart. A more
3315 # correct method would be to close all fds that were not
3316 # open when the process started, but this seems to be
3317 # hard. See "debugger 'R'estart and open database
3318 # connections" on p5p.
3320 my $max_fd = 1024; # default if POSIX can't be loaded
3321 if (eval { require POSIX }) {
3322 $max_fd = POSIX::sysconf(POSIX::_SC_OPEN_MAX());
3325 if (defined $max_fd) {
3326 foreach ($^F+1 .. $max_fd-1) {
3327 next unless open FD_TO_CLOSE, "<&=$_";
3332 # And run Perl again. We use exec() to keep the
3333 # PID stable (and that way $ini_pids is still valid).
3334 exec(@args) || print $OUT "exec failed: $!\n";
3339 =head4 C<|, ||> - pipe output through the pager.
3341 For C<|>, we save C<OUT> (the debugger's output filehandle) and C<STDOUT>
3342 (the program's standard output). For C<||>, we only save C<OUT>. We open a
3343 pipe to the pager (restoring the output filehandles if this fails). If this
3344 is the C<|> command, we also set up a C<SIGPIPE> handler which will simply
3345 set C<$signal>, sending us back into the debugger.
3347 We then trim off the pipe symbols and C<redo> the command loop at the
3348 C<PIPE> label, causing us to evaluate the command in C<$cmd> without
3353 # || - run command in the pager, with output to DB::OUT.
3354 $cmd =~ /^\|\|?\s*[^|]/ && do {
3355 if ( $pager =~ /^\|/ ) {
3357 # Default pager is into a pipe. Redirect I/O.
3358 open( SAVEOUT, ">&STDOUT" )
3359 || &warn("Can't save STDOUT");
3360 open( STDOUT, ">&OUT" )
3361 || &warn("Can't redirect STDOUT");
3362 } ## end if ($pager =~ /^\|/)
3365 # Not into a pipe. STDOUT is safe.
3366 open( SAVEOUT, ">&OUT" ) || &warn("Can't save DB::OUT");
3369 # Fix up environment to record we have less if so.
3372 unless ( $piped = open( OUT, $pager ) ) {
3374 # Couldn't open pipe to pager.
3375 &warn("Can't pipe output to `$pager'");
3376 if ( $pager =~ /^\|/ ) {
3378 # Redirect I/O back again.
3379 open( OUT, ">&STDOUT" ) # XXX: lost message
3380 || &warn("Can't restore DB::OUT");
3381 open( STDOUT, ">&SAVEOUT" )
3382 || &warn("Can't restore STDOUT");
3384 } ## end if ($pager =~ /^\|/)
3387 # Redirect I/O. STDOUT already safe.
3388 open( OUT, ">&STDOUT" ) # XXX: lost message
3389 || &warn("Can't restore DB::OUT");
3392 } ## end unless ($piped = open(OUT,...
3394 # Set up broken-pipe handler if necessary.
3395 $SIG{PIPE} = \&DB::catch
3397 && ( "" eq $SIG{PIPE} || "DEFAULT" eq $SIG{PIPE} );
3399 # Save current filehandle, unbuffer out, and put it back.
3400 $selected = select(OUT);
3403 # Don't put it back if pager was a pipe.
3404 select($selected), $selected = "" unless $cmd =~ /^\|\|/;
3406 # Trim off the pipe symbols and run the command now.
3407 $cmd =~ s/^\|+\s*//;
3411 =head3 END OF COMMAND PARSING
3413 Anything left in C<$cmd> at this point is a Perl expression that we want to
3414 evaluate. We'll always evaluate in the user's context, and fully qualify
3415 any variables we might want to address in the C<DB> package.
3419 # t - turn trace on.
3420 $cmd =~ s/^t\s/\$DB::trace |= 1;\n/;
3422 # s - single-step. Remember the last command was 's'.
3423 $cmd =~ s/^s\s/\$DB::single = 1;\n/ && do { $laststep = 's' };
3425 # n - single-step, but not into subs. Remember last command
3427 $cmd =~ s/^n\s/\$DB::single = 2;\n/ && do { $laststep = 'n' };
3431 # Make sure the flag that says "the debugger's running" is
3432 # still on, to make sure we get control again.
3433 $evalarg = "\$^D = \$^D | \$DB::db_stop;\n$cmd";
3435 # Run *our* eval that executes in the caller's context.
3438 # Turn off the one-time-dump stuff now.
3440 $onetimeDump = undef;
3441 $onetimedumpDepth = undef;
3443 elsif ( $term_pid == $$ ) {
3444 eval { # May run under miniperl, when not available...
3449 # XXX If this is the master pid, print a newline.
3452 } ## end while (($term || &setterm...
3454 =head3 POST-COMMAND PROCESSING
3456 After each command, we check to see if the command output was piped anywhere.
3457 If so, we go through the necessary code to unhook the pipe and go back to
3458 our standard filehandles for input and output.
3464 # At the end of every command:
3467 # Unhook the pipe mechanism now.
3468 if ( $pager =~ /^\|/ ) {
3470 # No error from the child.
3473 # we cannot warn here: the handle is missing --tchrist
3474 close(OUT) || print SAVEOUT "\nCan't close DB::OUT\n";
3476 # most of the $? crud was coping with broken cshisms
3477 # $? is explicitly set to 0, so this never runs.
3479 print SAVEOUT "Pager `$pager' failed: ";
3481 print SAVEOUT "shell returned -1\n";
3484 print SAVEOUT ( $? & 127 )
3485 ? " (SIG#" . ( $? & 127 ) . ")"
3486 : "", ( $? & 128 ) ? " -- core dumped" : "", "\n";
3489 print SAVEOUT "status ", ( $? >> 8 ), "\n";
3493 # Reopen filehandle for our output (if we can) and
3494 # restore STDOUT (if we can).
3495 open( OUT, ">&STDOUT" ) || &warn("Can't restore DB::OUT");
3496 open( STDOUT, ">&SAVEOUT" )
3497 || &warn("Can't restore STDOUT");
3499 # Turn off pipe exception handler if necessary.
3500 $SIG{PIPE} = "DEFAULT" if $SIG{PIPE} eq \&DB::catch;
3502 # Will stop ignoring SIGPIPE if done like nohup(1)
3503 # does SIGINT but Perl doesn't give us a choice.
3504 } ## end if ($pager =~ /^\|/)
3507 # Non-piped "pager". Just restore STDOUT.
3508 open( OUT, ">&SAVEOUT" ) || &warn("Can't restore DB::OUT");
3511 # Close filehandle pager was using, restore the normal one
3514 select($selected), $selected = "" unless $selected eq "";
3518 } ## end if ($piped)
3521 =head3 COMMAND LOOP TERMINATION
3523 When commands have finished executing, we come here. If the user closed the
3524 input filehandle, we turn on C<$fall_off_end> to emulate a C<q> command. We
3525 evaluate any post-prompt items. We restore C<$@>, C<$!>, C<$^E>, C<$,>, C<$/>,
3526 C<$\>, and C<$^W>, and return a null list as expected by the Perl interpreter.
3527 The interpreter will then execute the next line and then return control to us
3532 # No more commands? Quit.
3533 $fall_off_end = 1 unless defined $cmd; # Emulate `q' on EOF
3535 # Evaluate post-prompt commands.
3536 foreach $evalarg (@$post) {
3539 } # if ($single || $signal)
3541 # Put the user's globals back where you found them.
3542 ( $@, $!, $^E, $,, $/, $\, $^W ) = @saved;
3546 # The following code may be executed now:
3551 C<sub> is called whenever a subroutine call happens in the program being
3552 debugged. The variable C<$DB::sub> contains the name of the subroutine
3555 The core function of this subroutine is to actually call the sub in the proper
3556 context, capturing its output. This of course causes C<DB::DB> to get called
3557 again, repeating until the subroutine ends and returns control to C<DB::sub>
3558 again. Once control returns, C<DB::sub> figures out whether or not to dump the
3559 return value, and returns its captured copy of the return value as its own
3560 return value. The value then feeds back into the program being debugged as if
3561 C<DB::sub> hadn't been there at all.
3563 C<sub> does all the work of printing the subroutine entry and exit messages
3564 enabled by setting C<$frame>. It notes what sub the autoloader got called for,
3565 and also prints the return value if needed (for the C<r> command and if
3566 the 16 bit is set in C<$frame>).
3568 It also tracks the subroutine call depth by saving the current setting of
3569 C<$single> in the C<@stack> package global; if this exceeds the value in
3570 C<$deep>, C<sub> automatically turns on printing of the current depth by
3571 setting the C<4> bit in C<$single>. In any case, it keeps the current setting
3572 of stop/don't stop on entry to subs set as it currently is set.
3574 =head3 C<caller()> support
3576 If C<caller()> is called from the package C<DB>, it provides some
3577 additional data, in the following order:
3583 The package name the sub was in
3585 =item * C<$filename>
3587 The filename it was defined in
3591 The line number it was defined on
3593 =item * C<$subroutine>
3595 The subroutine name; C<(eval)> if an C<eval>().
3599 1 if it has arguments, 0 if not
3601 =item * C<$wantarray>
3603 1 if array context, 0 if scalar context
3605 =item * C<$evaltext>
3607 The C<eval>() text, if any (undefined for C<eval BLOCK>)
3609 =item * C<$is_require>
3611 frame was created by a C<use> or C<require> statement
3615 pragma information; subject to change between versions
3619 pragma information; subject to change between versions
3621 =item * C<@DB::args>
3623 arguments with which the subroutine was invoked
3630 # Do not use a regex in this subroutine -> results in corrupted memory
3631 # See: [perl #66110]
3633 # lock ourselves under threads
3636 # Whether or not the autoloader was running, a scalar to put the
3637 # sub's return value in (if needed), and an array to put the sub's
3638 # return value in (if needed).
3639 my ( $al, $ret, @ret ) = "";
3640 if ($sub eq 'threads::new' && $ENV{PERL5DB_THREADED}) {
3641 print "creating new thread\n";
3644 # If the last ten characters are '::AUTOLOAD', note we've traced
3645 # into AUTOLOAD for $sub.
3646 if ( length($sub) > 10 && substr( $sub, -10, 10 ) eq '::AUTOLOAD' ) {
3647 $al = " for $$sub" if defined $$sub;
3650 # We stack the stack pointer and then increment it to protect us
3651 # from a situation that might unwind a whole bunch of call frames
3652 # at once. Localizing the stack pointer means that it will automatically
3653 # unwind the same amount when multiple stack frames are unwound.
3654 local $stack_depth = $stack_depth + 1; # Protect from non-local exits
3657 $#stack = $stack_depth;
3659 # Save current single-step setting.
3660 $stack[-1] = $single;
3662 # Turn off all flags except single-stepping.
3665 # If we've gotten really deeply recursed, turn on the flag that will
3666 # make us stop with the 'deep recursion' message.
3667 $single |= 4 if $stack_depth == $deep;
3669 # If frame messages are on ...
3671 $frame & 4 # Extended frame entry message
3673 print_lineinfo( ' ' x ( $stack_depth - 1 ), "in " ),
3675 # Why -1? But it works! :-(
3676 # Because print_trace will call add 1 to it and then call
3677 # dump_trace; this results in our skipping -1+1 = 0 stack frames
3679 print_trace( $LINEINFO, -1, 1, 1, "$sub$al" )
3681 : print_lineinfo( ' ' x ( $stack_depth - 1 ), "entering $sub$al\n" )
3683 # standard frame entry message
3687 # Determine the sub's return type,and capture approppriately.
3690 # Called in array context. call sub and capture output.
3691 # DB::DB will recursively get control again if appropriate; we'll come
3692 # back here when the sub is finished.
3695 # Pop the single-step value back off the stack.
3696 $single |= $stack[ $stack_depth-- ];
3698 # Check for exit trace messages...
3700 $frame & 4 # Extended exit message
3702 print_lineinfo( ' ' x $stack_depth, "out " ),
3703 print_trace( $LINEINFO, -1, 1, 1, "$sub$al" )
3705 : print_lineinfo( ' ' x $stack_depth, "exited $sub$al\n" )
3707 # Standard exit message
3711 # Print the return info if we need to.
3712 if ( $doret eq $stack_depth or $frame & 16 ) {
3714 # Turn off output record separator.
3716 my $fh = ( $doret eq $stack_depth ? $OUT : $LINEINFO );
3718 # Indent if we're printing because of $frame tracing.
3719 print $fh ' ' x $stack_depth if $frame & 16;
3721 # Print the return value.
3722 print $fh "list context return from $sub:\n";
3723 dumpit( $fh, \@ret );
3725 # And don't print it again.
3727 } ## end if ($doret eq $stack_depth...
3728 # And we have to return the return value now.
3730 } ## end if (wantarray)
3734 if ( defined wantarray ) {
3736 # Save the value if it's wanted at all.
3741 # Void return, explicitly.
3746 # Pop the single-step value off the stack.
3747 $single |= $stack[ $stack_depth-- ];
3749 # If we're doing exit messages...
3751 $frame & 4 # Extended messsages
3753 print_lineinfo( ' ' x $stack_depth, "out " ),
3754 print_trace( $LINEINFO, -1, 1, 1, "$sub$al" )
3756 : print_lineinfo( ' ' x $stack_depth, "exited $sub$al\n" )
3762 # If we are supposed to show the return value... same as before.
3763 if ( $doret eq $stack_depth or $frame & 16 and defined wantarray ) {
3765 my $fh = ( $doret eq $stack_depth ? $OUT : $LINEINFO );
3766 print $fh ( ' ' x $stack_depth ) if $frame & 16;
3769 ? "scalar context return from $sub: "
3770 : "void context return from $sub\n"
3772 dumpit( $fh, $ret ) if defined wantarray;
3774 } ## end if ($doret eq $stack_depth...
3776 # Return the appropriate scalar value.
3778 } ## end else [ if (wantarray)
3783 # lock ourselves under threads
3786 # Whether or not the autoloader was running, a scalar to put the
3787 # sub's return value in (if needed), and an array to put the sub's
3788 # return value in (if needed).
3789 my ( $al, $ret, @ret ) = "";
3790 if ($sub =~ /^threads::new$/ && $ENV{PERL5DB_THREADED}) {
3791 print "creating new thread\n";
3794 # If the last ten characters are C'::AUTOLOAD', note we've traced
3795 # into AUTOLOAD for $sub.
3796 if ( length($sub) > 10 && substr( $sub, -10, 10 ) eq '::AUTOLOAD' ) {
3800 # We stack the stack pointer and then increment it to protect us
3801 # from a situation that might unwind a whole bunch of call frames
3802 # at once. Localizing the stack pointer means that it will automatically
3803 # unwind the same amount when multiple stack frames are unwound.
3804 local $stack_depth = $stack_depth + 1; # Protect from non-local exits
3807 $#stack = $stack_depth;
3809 # Save current single-step setting.
3810 $stack[-1] = $single;
3812 # Turn off all flags except single-stepping.
3815 # If we've gotten really deeply recursed, turn on the flag that will
3816 # make us stop with the 'deep recursion' message.
3817 $single |= 4 if $stack_depth == $deep;
3819 # If frame messages are on ...
3821 $frame & 4 # Extended frame entry message
3823 print_lineinfo( ' ' x ( $stack_depth - 1 ), "in " ),
3825 # Why -1? But it works! :-(
3826 # Because print_trace will call add 1 to it and then call
3827 # dump_trace; this results in our skipping -1+1 = 0 stack frames
3829 print_trace( $LINEINFO, -1, 1, 1, "$sub$al" )
3831 : print_lineinfo( ' ' x ( $stack_depth - 1 ), "entering $sub$al\n" )
3833 # standard frame entry message
3837 # Pop the single-step value back off the stack.
3838 $single |= $stack[ $stack_depth-- ];
3840 # call the original lvalue sub.
3844 =head1 EXTENDED COMMAND HANDLING AND THE COMMAND API
3846 In Perl 5.8.0, there was a major realignment of the commands and what they did,
3847 Most of the changes were to systematize the command structure and to eliminate
3848 commands that threw away user input without checking.
3850 The following sections describe the code added to make it easy to support
3851 multiple command sets with conflicting command names. This section is a start
3852 at unifying all command processing to make it simpler to develop commands.
3854 Note that all the cmd_[a-zA-Z] subroutines require the command name, a line
3855 number, and C<$dbline> (the current line) as arguments.
3857 Support functions in this section which have multiple modes of failure C<die>
3858 on error; the rest simply return a false value.
3860 The user-interface functions (all of the C<cmd_*> functions) just output
3865 The C<%set> hash defines the mapping from command letter to subroutine
3868 C<%set> is a two-level hash, indexed by set name and then by command name.
3869 Note that trying to set the CommandSet to C<foobar> simply results in the
3870 5.8.0 command set being used, since there's no top-level entry for C<foobar>.
3879 'A' => 'pre580_null',
3881 'B' => 'pre580_null',
3882 'd' => 'pre580_null',
3885 'M' => 'pre580_null',
3887 'o' => 'pre580_null',
3893 '<' => 'pre590_prepost',
3894 '<<' => 'pre590_prepost',
3895 '>' => 'pre590_prepost',
3896 '>>' => 'pre590_prepost',
3897 '{' => 'pre590_prepost',
3898 '{{' => 'pre590_prepost',
3902 =head2 C<cmd_wrapper()> (API)
3904 C<cmd_wrapper()> allows the debugger to switch command sets
3905 depending on the value of the C<CommandSet> option.
3907 It tries to look up the command in the C<%set> package-level I<lexical>
3908 (which means external entities can't fiddle with it) and create the name of
3909 the sub to call based on the value found in the hash (if it's there). I<All>
3910 of the commands to be handled in a set have to be added to C<%set>; if they
3911 aren't found, the 5.8.0 equivalent is called (if there is one).
3913 This code uses symbolic references.
3920 my $dblineno = shift;
3922 # Assemble the command subroutine's name by looking up the
3923 # command set and command name in %set. If we can't find it,
3924 # default to the older version of the command.
3926 . ( $set{$CommandSet}{$cmd}
3927 || ( $cmd =~ /^[<>{]+/o ? 'prepost' : $cmd ) );
3929 # Call the command subroutine, call it by name.
3930 return &$call( $cmd, $line, $dblineno );
3931 } ## end sub cmd_wrapper
3933 =head3 C<cmd_a> (command)
3935 The C<a> command handles pre-execution actions. These are associated with a
3936 particular line, so they're stored in C<%dbline>. We default to the current
3937 line if none is specified.
3943 my $line = shift || ''; # [.|line] expr
3946 # If it's dot (here), or not all digits, use the current line.
3947 $line =~ s/^(\.|(?:[^\d]))/$dbline/;
3949 # Should be a line number followed by an expression.
3950 if ( $line =~ /^\s*(\d*)\s*(\S.+)/ ) {
3951 my ( $lineno, $expr ) = ( $1, $2 );
3953 # If we have an expression ...
3954 if ( length $expr ) {
3956 # ... but the line isn't breakable, complain.
3957 if ( $dbline[$lineno] == 0 ) {
3959 "Line $lineno($dbline[$lineno]) does not have an action?\n";
3963 # It's executable. Record that the line has an action.
3964 $had_breakpoints{$filename} |= 2;
3966 # Remove any action, temp breakpoint, etc.
3967 $dbline{$lineno} =~ s/\0[^\0]*//;
3969 # Add the action to the line.
3970 $dbline{$lineno} .= "\0" . action($expr);
3972 } ## end if (length $expr)
3973 } ## end if ($line =~ /^\s*(\d*)\s*(\S.+)/)
3978 "Adding an action requires an optional lineno and an expression\n"
3983 =head3 C<cmd_A> (command)
3985 Delete actions. Similar to above, except the delete code is in a separate
3986 subroutine, C<delete_action>.
3992 my $line = shift || '';
3996 $line =~ s/^\./$dbline/;
3998 # Call delete_action with a null param to delete them all.
3999 # The '1' forces the eval to be true. It'll be false only
4000 # if delete_action blows up for some reason, in which case
4001 # we print $@ and get out.
4002 if ( $line eq '*' ) {
4003 eval { &delete_action(); 1 } or print $OUT $@ and return;
4006 # There's a real line number. Pass it to delete_action.
4007 # Error trapping is as above.
4008 elsif ( $line =~ /^(\S.*)/ ) {
4009 eval { &delete_action($1); 1 } or print $OUT $@ and return;
4012 # Swing and a miss. Bad syntax.
4015 "Deleting an action requires a line number, or '*' for all\n" ; # hint
4019 =head3 C<delete_action> (API)
4021 C<delete_action> accepts either a line number or C<undef>. If a line number
4022 is specified, we check for the line being executable (if it's not, it
4023 couldn't have had an action). If it is, we just take the action off (this
4024 will get any kind of an action, including breakpoints).
4030 if ( defined($i) ) {
4033 die "Line $i has no action .\n" if $dbline[$i] == 0;
4035 # Nuke whatever's there.
4036 $dbline{$i} =~ s/\0[^\0]*//; # \^a
4037 delete $dbline{$i} if $dbline{$i} eq '';
4040 print $OUT "Deleting all actions...\n";
4041 for my $file ( keys %had_breakpoints ) {
4042 local *dbline = $main::{ '_<' . $file };
4045 for ( $i = 1 ; $i <= $max ; $i++ ) {
4046 if ( defined $dbline{$i} ) {
4047 $dbline{$i} =~ s/\0[^\0]*//;
4048 delete $dbline{$i} if $dbline{$i} eq '';
4050 unless ( $had_breakpoints{$file} &= ~2 ) {
4051 delete $had_breakpoints{$file};
4053 } ## end for ($i = 1 ; $i <= $max...
4054 } ## end for my $file (keys %had_breakpoints)
4055 } ## end else [ if (defined($i))
4056 } ## end sub delete_action
4058 =head3 C<cmd_b> (command)
4060 Set breakpoints. Since breakpoints can be set in so many places, in so many
4061 ways, conditionally or not, the breakpoint code is kind of complex. Mostly,
4062 we try to parse the command type, and then shuttle it off to an appropriate
4063 subroutine to actually do the work of setting the breakpoint in the right
4070 my $line = shift; # [.|line] [cond]
4073 # Make . the current line number if it's there..
4074 $line =~ s/^\./$dbline/;
4076 # No line number, no condition. Simple break on current line.
4077 if ( $line =~ /^\s*$/ ) {
4078 &cmd_b_line( $dbline, 1 );
4081 # Break on load for a file.
4082 elsif ( $line =~ /^load\b\s*(.*)/ ) {
4088 # b compile|postpone <some sub> [<condition>]
4089 # The interpreter actually traps this one for us; we just put the
4090 # necessary condition in the %postponed hash.
4091 elsif ( $line =~ /^(postpone|compile)\b\s*([':A-Za-z_][':\w]*)\s*(.*)/ ) {
4093 # Capture the condition if there is one. Make it true if none.
4094 my $cond = length $3 ? $3 : '1';
4096 # Save the sub name and set $break to 1 if $1 was 'postpone', 0
4097 # if it was 'compile'.
4098 my ( $subname, $break ) = ( $2, $1 eq 'postpone' );
4100 # De-Perl4-ify the name - ' separators to ::.
4101 $subname =~ s/\'/::/g;
4103 # Qualify it into the current package unless it's already qualified.
4104 $subname = "${'package'}::" . $subname unless $subname =~ /::/;
4106 # Add main if it starts with ::.
4107 $subname = "main" . $subname if substr( $subname, 0, 2 ) eq "::";
4109 # Save the break type for this sub.
4110 $postponed{$subname} = $break ? "break +0 if $cond" : "compile";
4111 } ## end elsif ($line =~ ...
4113 # b <sub name> [<condition>]
4114 elsif ( $line =~ /^([':A-Za-z_][':\w]*(?:\[.*\])?)\s*(.*)/ ) {
4118 $cond = length $2 ? $2 : '1';
4119 &cmd_b_sub( $subname, $cond );
4122 # b <line> [<condition>].
4123 elsif ( $line =~ /^(\d*)\s*(.*)/ ) {
4125 # Capture the line. If none, it's the current line.
4126 $line = $1 || $dbline;
4128 # If there's no condition, make it '1'.
4129 $cond = length $2 ? $2 : '1';
4132 &cmd_b_line( $line, $cond );
4135 # Line didn't make sense.
4137 print "confused by line($line)?\n";
4141 =head3 C<break_on_load> (API)
4143 We want to break when this file is loaded. Mark this file in the
4144 C<%break_on_load> hash, and note that it has a breakpoint in
4145 C<%had_breakpoints>.
4151 $break_on_load{$file} = 1;
4152 $had_breakpoints{$file} |= 1;
4155 =head3 C<report_break_on_load> (API)
4157 Gives us an array of filenames that are set to break on load. Note that
4158 only files with break-on-load are in here, so simply showing the keys
4163 sub report_break_on_load {
4164 sort keys %break_on_load;
4167 =head3 C<cmd_b_load> (command)
4169 We take the file passed in and try to find it in C<%INC> (which maps modules
4170 to files they came from). We mark those files for break-on-load via
4171 C<break_on_load> and then report that it was done.
4179 # This is a block because that way we can use a redo inside it
4180 # even without there being any looping structure at all outside it.
4183 # Save short name and full path if found.
4185 push @files, $::INC{$file} if $::INC{$file};
4187 # Tack on .pm and do it again unless there was a '.' in the name
4189 $file .= '.pm', redo unless $file =~ /\./;
4192 # Do the real work here.
4193 break_on_load($_) for @files;
4195 # All the files that have break-on-load breakpoints.
4196 @files = report_break_on_load;
4198 # Normalize for the purposes of our printing this.
4201 print $OUT "Will stop on load of `@files'.\n";
4202 } ## end sub cmd_b_load
4204 =head3 C<$filename_error> (API package global)
4206 Several of the functions we need to implement in the API need to work both
4207 on the current file and on other files. We don't want to duplicate code, so
4208 C<$filename_error> is used to contain the name of the file that's being
4209 worked on (if it's not the current one).
4211 We can now build functions in pairs: the basic function works on the current
4212 file, and uses C<$filename_error> as part of its error message. Since this is
4213 initialized to C<"">, no filename will appear when we are working on the
4216 The second function is a wrapper which does the following:
4222 Localizes C<$filename_error> and sets it to the name of the file to be processed.
4226 Localizes the C<*dbline> glob and reassigns it to point to the file we want to process.
4230 Calls the first function.
4232 The first function works on the I<current> file (i.e., the one we changed to),
4233 and prints C<$filename_error> in the error message (the name of the other file)
4234 if it needs to. When the functions return, C<*dbline> is restored to point
4235 to the actual current file (the one we're executing in) and
4236 C<$filename_error> is restored to C<"">. This restores everything to
4237 the way it was before the second function was called at all.
4239 See the comments in C<breakable_line> and C<breakable_line_in_file> for more
4246 $filename_error = '';
4248 =head3 breakable_line(from, to) (API)
4250 The subroutine decides whether or not a line in the current file is breakable.
4251 It walks through C<@dbline> within the range of lines specified, looking for
4252 the first line that is breakable.
4254 If C<$to> is greater than C<$from>, the search moves forwards, finding the
4255 first line I<after> C<$to> that's breakable, if there is one.
4257 If C<$from> is greater than C<$to>, the search goes I<backwards>, finding the
4258 first line I<before> C<$to> that's breakable, if there is one.
4262 sub breakable_line {
4264 my ( $from, $to ) = @_;
4266 # $i is the start point. (Where are the FORTRAN programs of yesteryear?)
4269 # If there are at least 2 arguments, we're trying to search a range.
4272 # $delta is positive for a forward search, negative for a backward one.
4273 my $delta = $from < $to ? +1 : -1;
4275 # Keep us from running off the ends of the file.
4276 my $limit = $delta > 0 ? $#dbline : 1;
4278 # Clever test. If you're a mathematician, it's obvious why this
4279 # test works. If not:
4280 # If $delta is positive (going forward), $limit will be $#dbline.
4281 # If $to is less than $limit, ($limit - $to) will be positive, times
4282 # $delta of 1 (positive), so the result is > 0 and we should use $to
4283 # as the stopping point.
4285 # If $to is greater than $limit, ($limit - $to) is negative,
4286 # times $delta of 1 (positive), so the result is < 0 and we should
4287 # use $limit ($#dbline) as the stopping point.
4289 # If $delta is negative (going backward), $limit will be 1.
4290 # If $to is zero, ($limit - $to) will be 1, times $delta of -1
4291 # (negative) so the result is > 0, and we use $to as the stopping
4294 # If $to is less than zero, ($limit - $to) will be positive,
4295 # times $delta of -1 (negative), so the result is not > 0, and
4296 # we use $limit (1) as the stopping point.
4298 # If $to is 1, ($limit - $to) will zero, times $delta of -1
4299 # (negative), still giving zero; the result is not > 0, and
4300 # we use $limit (1) as the stopping point.
4302 # if $to is >1, ($limit - $to) will be negative, times $delta of -1
4303 # (negative), giving a positive (>0) value, so we'll set $limit to
4306 $limit = $to if ( $limit - $to ) * $delta > 0;
4308 # The real search loop.
4309 # $i starts at $from (the point we want to start searching from).
4310 # We move through @dbline in the appropriate direction (determined
4311 # by $delta: either -1 (back) or +1 (ahead).
4312 # We stay in as long as we haven't hit an executable line
4313 # ($dbline[$i] == 0 means not executable) and we haven't reached
4314 # the limit yet (test similar to the above).
4315 $i += $delta while $dbline[$i] == 0 and ( $limit - $i ) * $delta > 0;
4317 } ## end if (@_ >= 2)
4319 # If $i points to a line that is executable, return that.
4320 return $i unless $dbline[$i] == 0;
4322 # Format the message and print it: no breakable lines in range.
4323 my ( $pl, $upto ) = ( '', '' );
4324 ( $pl, $upto ) = ( 's', "..$to" ) if @_ >= 2 and $from != $to;
4326 # If there's a filename in filename_error, we'll see it.
4328 die "Line$pl $from$upto$filename_error not breakable\n";
4329 } ## end sub breakable_line
4331 =head3 breakable_line_in_filename(file, from, to) (API)
4333 Like C<breakable_line>, but look in another file.
4337 sub breakable_line_in_filename {
4339 # Capture the file name.
4342 # Swap the magic line array over there temporarily.
4343 local *dbline = $main::{ '_<' . $f };
4345 # If there's an error, it's in this other file.
4346 local $filename_error = " of `$f'";
4348 # Find the breakable line.
4351 # *dbline and $filename_error get restored when this block ends.
4353 } ## end sub breakable_line_in_filename
4355 =head3 break_on_line(lineno, [condition]) (API)
4357 Adds a breakpoint with the specified condition (or 1 if no condition was
4358 specified) to the specified line. Dies if it can't.
4363 my ( $i, $cond ) = @_;
4365 # Always true if no condition supplied.
4366 $cond = 1 unless @_ >= 2;
4372 # Woops, not a breakable line. $filename_error allows us to say
4373 # if it was in a different file.
4374 die "Line $i$filename_error not breakable.\n" if $dbline[$i] == 0;
4376 # Mark this file as having breakpoints in it.
4377 $had_breakpoints{$filename} |= 1;
4379 # If there is an action or condition here already ...
4380 if ( $dbline{$i} ) {
4382 # ... swap this condition for the existing one.
4383 $dbline{$i} =~ s/^[^\0]*/$cond/;
4387 # Nothing here - just add the condition.
4388 $dbline{$i} = $cond;
4390 } ## end sub break_on_line
4392 =head3 cmd_b_line(line, [condition]) (command)
4394 Wrapper for C<break_on_line>. Prints the failure message if it
4400 eval { break_on_line(@_); 1 } or do {
4402 print $OUT $@ and return;
4404 } ## end sub cmd_b_line
4406 =head3 break_on_filename_line(file, line, [condition]) (API)
4408 Switches to the file specified and then calls C<break_on_line> to set
4413 sub break_on_filename_line {
4414 my ( $f, $i, $cond ) = @_;
4416 # Always true if condition left off.
4417 $cond = 1 unless @_ >= 3;
4419 # Switch the magical hash temporarily.
4420 local *dbline = $main::{ '_<' . $f };
4422 # Localize the variables that break_on_line uses to make its message.
4423 local $filename_error = " of `$f'";
4424 local $filename = $f;
4426 # Add the breakpoint.
4427 break_on_line( $i, $cond );
4428 } ## end sub break_on_filename_line
4430 =head3 break_on_filename_line_range(file, from, to, [condition]) (API)
4432 Switch to another file, search the range of lines specified for an
4433 executable one, and put a breakpoint on the first one you find.
4437 sub break_on_filename_line_range {
4438 my ( $f, $from, $to, $cond ) = @_;
4440 # Find a breakable line if there is one.
4441 my $i = breakable_line_in_filename( $f, $from, $to );
4443 # Always true if missing.
4444 $cond = 1 unless @_ >= 3;
4446 # Add the breakpoint.
4447 break_on_filename_line( $f, $i, $cond );
4448 } ## end sub break_on_filename_line_range
4450 =head3 subroutine_filename_lines(subname, [condition]) (API)
4452 Search for a subroutine within a given file. The condition is ignored.
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