# Documentation is at the __END__
my ($running, $ready, $deep, $usrctxt, $evalarg,
@stack, @saved, @skippkg, @clients);
# Globals - must be defined at startup so that clients can refer to
# them right after a C<require DB;>
# these are hardcoded in perl source (some are magical)
$DB::sub = ''; # name of current subroutine
%DB::sub = (); # "filename:fromline-toline" for every known sub
$DB::single
= 0; # single-step flag (set it to 1 to enable stops in BEGIN/use)
$DB::signal
= 0; # signal flag (will cause a stop at the next line)
$DB::trace
= 0; # are we tracing through subroutine calls?
@DB::args
= (); # arguments of current subroutine or @ARGV array
@DB::dbline
= (); # list of lines in currently loaded file
%DB::dbline
= (); # actions in current file (keyed by line number)
@DB::ret
= (); # return value of last sub executed in list context
$DB::ret
= ''; # return value of last sub executed in scalar context
$DB::package = ''; # current package space
$DB::filename
= ''; # current filename
$DB::subname
= ''; # currently executing sub (fullly qualified name)
$DB::lineno
= ''; # current line number
$DB::VERSION
= $DB::VERSION
= '1.01';
# initialize private globals to avoid warnings
$running = 1; # are we running, or are we stopped?
# entry point for all subroutine calls
push(@stack, $DB::single
);
$DB::single
|= 4 if $#stack == $deep;
if ($DB::sub eq 'DESTROY' or substr($DB::sub, -9) eq '::DESTROY' or not defined wantarray) {
$DB::single
|= pop(@stack);
$DB::single
|= pop(@stack);
$DB::single
|= pop(@stack);
# this is called by perl for every statement
($DB::package, $DB::filename
, $DB::lineno
) = caller;
return if @skippkg and grep { $_ eq $DB::package } @skippkg;
$usrctxt = "package $DB::package;"; # this won't let them modify, alas
local(*DB
::dbline
) = "::_<$DB::filename";
# we need to check for pseudofiles on Mac OS (these are files
# not attached to a filename, but instead stored in Dev:Pseudo)
# since this is done late, $DB::filename will be "wrong" after
if ($^O
eq 'MacOS' && $#DB::dbline
< 0) {
$DB::filename
= 'Dev:Pseudo';
*DB
::dbline
= "::_<$DB::filename";
if (($stop,$action) = split(/\0/,$DB::dbline
{$DB::lineno
})) {
$stop = 0 unless $stop; # avoid un_init warning
$evalarg = "\$DB::signal |= do { $stop; }"; &eval;
$DB::dbline
{$DB::lineno
} =~ s/;9($|\0)/$1/; # clear any temp breakpt
if ($DB::single
|| $DB::trace
|| $DB::signal
) {
$DB::subname
= ($DB::sub =~ /\'|::/) ?
$DB::sub : "${DB::package}::$DB::sub"; #';
DB
->loadfile($DB::filename
, $DB::lineno
);
$evalarg = $action, &eval if $action;
if ($DB::single
|| $DB::signal
) {
_outputall
($#stack . " levels deep in subroutine calls.\n") if $DB::single
& 4;
&eval if ($evalarg = DB
->prestop);
# perform any client-specific prestop actions
&eval if ($evalarg = $c->cprestop);
# Now sit in an event loop until something sets $running
$c->idle; # call client event loop; must not block
if ($running == 2) { # client wants something eval-ed
&eval if ($evalarg = $c->evalcode);
# perform any client-specific poststop actions
&eval if ($evalarg = $c->cpoststop);
&eval if ($evalarg = DB
->poststop);
($@
, $!, $,, $/, $\
, $^W
) = @saved;
# this takes its argument via $evalarg to preserve current @_
($@
, $!, $,, $/, $\
, $^W
) = @saved;
eval "$usrctxt $evalarg; &DB::save";
###############################################################################
# no compile-time subroutine call allowed before this point #
###############################################################################
use strict
; # this can run only after DB() and sub() are defined
@saved = ($@
, $!, $,, $/, $\
, $^W
);
$, = ""; $/ = "\n"; $\
= ""; $^W
= 0;
for (@clients) { $_->awaken; }
# Client callable (read inheritable) methods defined after this point
$s = _clientname
($s) if ref($s);
$s = _clientname
($s) if ref($s);
@clients = grep {$_ ne $s} @clients;
# $running = 3 unless @clients;
"$name" =~ /^(.+)=[A-Z]+\(.+\)$/;
$s->set_tbreak($i) if $i;
for ($i = 0; $i <= $#stack;) {
# XXX caller must experimentally determine $i (since it depends
# on how many client call frames are between this call and the DB call).
my $i = shift; # how many levels to get to DB sub
$i = 0 unless defined $i;
# XXX caller must experimentally determine $start (since it depends
# on how many client call frames are between this call and the DB call).
my($p,$f,$l,$s,$h,$w,$e,$r,$a, @a, @ret,$i);
$start = 1 unless $start;
for ($i = $start; ($p,$f,$l,$s,$h,$w,$e,$r) = caller($i); $i++) {
s/([^\0]*)/'$1'/ unless /^-?[\d.]+$/;
s/([\200-\377])/sprintf("M-%c",ord($1)&0177)/eg;
s/([\0-\37\177])/sprintf("^%c",ord($1)^64)/eg;
$w = $w ?
'@ = ' : '$ = ';
$a = $h ?
'(' . join(', ', @a) . ')' : '';
$e =~ s/\n\s*\;\s*\Z// if $e;
$e =~ s/[\\\']/\\$1/g if $e;
} elsif ($s eq '(eval)') {
$f = "file `$f'" unless $f eq '-e';
push @ret, "$w&$s$a from $f line $l";
$DB::trace
= !$DB::trace
;
# without args: returns all defined subroutine names
# with subname args: returns a listref [file, start, end]
push @ret, [$DB::sub{$name} =~ /^(.*)\:(\d+)-(\d+)$/]
if exists $DB::sub{$name};
# first argument is a filename whose subs will be returned
# if a filename is not supplied, all subs in the current
$fname = $DB::filename
unless $fname;
return grep { $DB::sub{$_} =~ /^$fname/ } keys %DB::sub;
# returns a list of all filenames that DB knows about
my(@f) = grep(m
|^_
<|, keys %main::);
return map { substr($_,2) } @f;
# returns reference to an array holding the lines in currently
if (!defined $main::{'_<' . $file}) {
if (($try) = grep(m
|^_
<.*$file|, keys %main::)) {
if (defined($main::{'_<' . $file})) {
# _outputall("Loading file $file..");
*DB
::dbline
= "::_<$file";
# print "2 ", $file, '|', $line, "\n";
$c->showfile($file, $line);
$fname = $DB::filename
unless $fname;
local(*DB
::dbline
) = "::_<$fname";
for ($i = 1; $i <= $#DB::dbline
; $i++) {
$ret{$i} = [$DB::dbline
[$i], split(/\0/, $DB::dbline
{$i})]
if defined $DB::dbline
{$i};
$i = _find_subline
($i) if ($i =~ /\D/);
$s->output("Subroutine not found.\n") unless $i;
if ($DB::dbline
[$i] == 0) {
$s->output("Line $i not breakable.\n");
$DB::dbline
{$i} =~ s/^[^\0]*/$cond/;
$i = _find_subline
($i) if ($i =~ /\D/);
$s->output("Subroutine not found.\n") unless $i;
if ($DB::dbline
[$i] == 0) {
$s->output("Line $i not breakable.\n");
$DB::dbline
{$i} =~ s/($|\0)/;9$1/; # add one-time-only b.p.
$name = "${DB::package}\:\:" . $name if $name !~ /::/;
$name = "main" . $name if substr($name,0,2) eq "::";
my($fname, $from, $to) = ($DB::sub{$name} =~ /^(.*):(\d+)-(\d+)$/);
local *DB
::dbline
= "::_<$fname";
++$from while $DB::dbline
[$from] == 0 && $from < $to;
$i = _find_subline
($i) if ($i =~ /\D/);
$s->output("Subroutine not found.\n") unless $i;
if (defined $DB::dbline
{$i}) {
$DB::dbline
{$i} =~ s/^[^\0]+//;
if ($DB::dbline
{$i} =~ s/^\0?$//) {
for ($i = 1; $i <= $#DB::dbline
; $i++) {
if (defined $DB::dbline
{$i}) {
$DB::dbline
{$i} =~ s/^[^\0]+//;
if ($DB::dbline
{$i} =~ s/^\0?$//) {
$i = _find_subline
($i) if ($i =~ /\D/);
$s->output("Subroutine not found.\n") unless $i;
if ($DB::dbline
[$i] == 0) {
$s->output("Line $i not actionable.\n");
$DB::dbline
{$i} =~ s/\0[^\0]*//;
$DB::dbline
{$i} .= "\0" . $act;
$i = _find_subline
($i) if ($i =~ /\D/);
$s->output("Subroutine not found.\n") unless $i;
if ($i && $DB::dbline
[$i] != 0) {
$DB::dbline
{$i} =~ s/\0[^\0]*//;
delete $DB::dbline
{$i} if $DB::dbline
{$i} =~ s/^\0?$//;
for ($i = 1; $i <= $#DB::dbline
; $i++) {
if (defined $DB::dbline
{$i}) {
$DB::dbline
{$i} =~ s/\0[^\0]*//;
delete $DB::dbline
{$i} if $DB::dbline
{$i} =~ s/^\0?$//;
return defined($val) ?
$preeval->{$client} = $val : $preeval->{$client};
return defined($val) ?
$posteval->{$client} = $val : $posteval->{$client};
# client-specific pre/post-stop actions.
# client complete startup
$running = 2; # hand over to DB() to evaluate in its context
$ineval->{$client} = $val;
return $ineval->{$client};
for (@clients) { $_->init }
$SIG{'INT'} = \
&DB
::catch
;
# disable this if stepping through END blocks is desired
# (looks scary and deconstructivist with Swat)
DB - programmatic interface to the Perl debugging API (draft, subject to
# these (inherited) methods can be called by the client
CLIENT->register() # register a client package name
CLIENT->done() # de-register from the debugging API
CLIENT->skippkg('hide::hide') # ask DB not to stop in this package
CLIENT->cont([WHERE]) # run some more (until BREAK or another breakpt)
CLIENT->step() # single step
CLIENT->next() # step over
CLIENT->ret() # return from current subroutine
CLIENT->backtrace() # return the call stack description
CLIENT->ready() # call when client setup is done
CLIENT->trace_toggle() # toggle subroutine call trace mode
CLIENT->subs([SUBS]) # return subroutine information
CLIENT->files() # return list of all files known to DB
CLIENT->lines() # return lines in currently loaded file
CLIENT->loadfile(FILE,LINE) # load a file and let other clients know
CLIENT->lineevents() # return info on lines with actions
CLIENT->set_break([WHERE],[COND])
CLIENT->set_tbreak([WHERE])
CLIENT->clr_breaks([LIST])
CLIENT->set_action(WHERE,ACTION)
CLIENT->clr_actions([LIST])
CLIENT->evalcode(STRING) # eval STRING in executing code's context
CLIENT->prestop([STRING]) # execute in code context before stopping
CLIENT->poststop([STRING])# execute in code context before resuming
# These methods will be called at the appropriate times.
# Stub versions provided do nothing.
# None of these can block.
CLIENT->init() # called when debug API inits itself
CLIENT->stop(FILE,LINE) # when execution stops
CLIENT->idle() # while stopped (can be a client event loop)
CLIENT->cleanup() # just before exit
CLIENT->output(LIST) # called to print any output that API must show
Perl debug information is frequently required not just by debuggers,
but also by modules that need some "special" information to do their
job properly, like profilers.
This module abstracts and provides all of the hooks into Perl internal
debugging functionality, so that various implementations of Perl debuggers
(or packages that want to simply get at the "privileged" debugging data)
can all benefit from the development of this common code. Currently used
by Swat, the perl/Tk GUI debugger.
Note that multiple "front-ends" can latch into this debugging API
simultaneously. This is intended to facilitate things like
debugging with a command line and GUI at the same time, debugging
debuggers etc. [Sounds nice, but this needs some serious support -- GSAR]
In particular, this API does B<not> provide the following functions:
user interface (tty or graphical)
These are intended to be services performed by the clients of this API.
This module attempts to be squeaky clean w.r.t C<use strict;> and when
The following "public" global names can be read by clients of this API.
Beware that these should be considered "readonly".
Name of current executing subroutine.
The keys of this hash are the names of all the known subroutines. Each value
is an encoded string that has the sprintf(3) format
C<("%s:%d-%d", filename, fromline, toline)>.
Single-step flag. Will be true if the API will stop at the next statement.
Signal flag. Will be set to a true value if a signal was caught. Clients may
check for this flag to abort time-consuming operations.
This flag is set to true if the API is tracing through subroutine calls.
Contains the arguments of current subroutine, or the C<@ARGV> array if in the
List of lines in currently loaded file.
Actions in current file (keys are line numbers). The values are strings that
have the sprintf(3) format C<("%s\000%s", breakcondition, actioncode)>.
Package namespace of currently executing code.
Currently loaded filename.
Fully qualified name of currently executing subroutine.
Line number that will be executed next.
The following are methods in the DB base class. A client must
access these methods by inheritance (*not* by calling them directly),
since the API keeps track of clients through the inheritance
register a client object/package
=item CLIENT->evalcode(STRING)
eval STRING in executing code context
=item CLIENT->skippkg('D::hide')
ask DB not to stop in these packages
run some more (until a breakpt is reached)
de-register from the debugging API
=head2 Client Callback Methods
The following "virtual" methods can be defined by the client. They will
be called by the API at appropriate points. Note that unless specified
otherwise, the debug API only defines empty, non-functional default versions
Called after debug API inits itself.
=item CLIENT->prestop([STRING])
Usually inherited from DB package. If no arguments are passed,
returns the prestop action string.
Called when execution stops (w/ args file, line).
Called while stopped (can be a client event loop).
=item CLIENT->poststop([STRING])
Usually inherited from DB package. If no arguments are passed,
returns the poststop action string.
=item CLIENT->evalcode(STRING)
Usually inherited from DB package. Ask for a STRING to be C<eval>-ed
in executing code context.
=item CLIENT->output(LIST)
Called when API must show a message (warnings, errors etc.).
The interface defined by this module is missing some of the later additions
to perl's debugging functionality. As such, this interface should be considered
highly experimental and subject to change.
Gurusamy Sarathy gsar@activestate.com
This code heavily adapted from an early version of perl5db.pl attributable
to Larry Wall and the Perl Porters.