From: Gurusamy Sarathy Date: Tue, 14 Mar 2000 05:49:08 +0000 (+0000) Subject: patches for many bugs in the debugger; documentation updates for X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=055fd3a96a4b067d75446c3d47ffc318e9acc40d;p=p5sagit%2Fp5-mst-13.2.git patches for many bugs in the debugger; documentation updates for perldelta; split perldebug.pod into perldeb{ug,guts}.pod (from Tom Christiansen) p4raw-id: //depot/perl@5723 --- diff --git a/MANIFEST b/MANIFEST index f097747..c3b1ed5 100644 --- a/MANIFEST +++ b/MANIFEST @@ -1065,6 +1065,7 @@ pod/perlcall.pod Callback info pod/perlcompile.pod Info on using the Compiler suite pod/perldata.pod Data structure info pod/perldbmfilter.pod Info about DBM Filters +pod/perldebguts.pod Debugger guts info pod/perldebug.pod Debugger info pod/perldelta.pod Changes since last version pod/perldiag.pod Diagnostic info diff --git a/lib/perl5db.pl b/lib/perl5db.pl index 7c5b0a9..bc545c6 100644 --- a/lib/perl5db.pl +++ b/lib/perl5db.pl @@ -2,17 +2,9 @@ package DB; # Debugger for Perl 5.00x; perl5db.pl patch level: -$VERSION = 1.06; +$VERSION = 1.07; $header = "perl5db.pl version $VERSION"; -# Enhanced by ilya@math.ohio-state.edu (Ilya Zakharevich) -# Latest version available: ftp://ftp.math.ohio-state.edu/pub/users/ilya/perl - -# modified Perl debugger, to be run from Emacs in perldb-mode -# Ray Lischner (uunet!mntgfx!lisch) as of 5 Nov 1990 -# Johan Vromans -- upgrade to 4.0 pl 10 -# Ilya Zakharevich -- patches after 5.001 (and some before ;-) - # # This file is automatically included if you do perl -d. # It's probably not useful to include this yourself. @@ -88,6 +80,15 @@ $header = "perl5db.pl version $VERSION"; # reset LineInfo to something "interactive"!) # ################################################################## + +# Enhanced by ilya@math.ohio-state.edu (Ilya Zakharevich) +# Latest version available: ftp://ftp.math.ohio-state.edu/pub/users/ilya/perl + +# modified Perl debugger, to be run from Emacs in perldb-mode +# Ray Lischner (uunet!mntgfx!lisch) as of 5 Nov 1990 +# Johan Vromans -- upgrade to 4.0 pl 10 +# Ilya Zakharevich -- patches after 5.001 (and some before ;-) + # Changelog: # A lot of things changed after 0.94. First of all, core now informs @@ -144,6 +145,48 @@ $header = "perl5db.pl version $VERSION"; # `b load' strips trailing whitespace. # completion ignores leading `|'; takes into account current package # when completing a subroutine name (same for `l'). +# Changes: 1.07: Many fixed by tchrist 13-March-2000 +# BUG FIXES: +# + Added bare mimimal security checks on perldb rc files, plus +# comments on what else is needed. +# + Fixed the ornaments that made "|h" completely unusable. +# They are not used in print_help if they will hurt. Strip pod +# if we're paging to less. +# + Fixed mis-formatting of help messages caused by ornaments +# to restore Larry's original formatting. +# + Fixed many other formatting errors. The code is still suboptimal, +# and needs a lot of work at restructuing. It's also misindented +# in many places. +# + Fixed bug where trying to look at an option like your pager +# shows "1". +# + Fixed some $? processing. Note: if you use csh or tcsh, you will +# lose. You should consider shell escapes not using their shell, +# or else not caring about detailed status. This should really be +# unified into one place, too. +# + Fixed bug where invisible trailing whitespace on commands hoses you, +# tricking Perl into thinking you wern't calling a debugger command! +# + Fixed bug where leading whitespace on commands hoses you. (One +# suggests a leading semicolon or any other irrelevant non-whitespace +# to indicate literal Perl code.) +# + Fixed bugs that ate warnings due to wrong selected handle. +# + Fixed a precedence bug on signal stuff. +# + Fixed some unseemly wording. +# + Fixed bug in help command trying to call perl method code. +# + Fixed to call dumpvar from exception handler. SIGPIPE killed us. +# ENHANCEMENTS: +# + Added some comments. This code is still nasty spaghetti. +# + Added message if you clear your pre/post command stacks which was +# very easy to do if you just typed a bare >, <, or {. (A command +# without an argument should *never* be a destructive action; this +# API is fundamentally screwed up; likewise option setting, which +# is equally buggered.) +# + Added command stack dump on argument of "?" for >, <, or {. +# + Added a semi-built-in doc viewer command that calls man with the +# proper %Config::Config path (and thus gets caching, man -k, etc), +# or else perldoc on obstreperous platforms. +# + Added to and rearranged the help information. +# + Detected apparent misuse of { ... } to declare a block; this used +# to work but now is a command, and mysteriously gave no complaint. #################################################################### @@ -237,36 +280,86 @@ $signalLevel = 1 unless defined $signalLevel; $pre = [] unless defined $pre; $post = [] unless defined $post; $pretype = [] unless defined $pretype; + warnLevel($warnLevel); dieLevel($dieLevel); signalLevel($signalLevel); -&pager((defined($ENV{PAGER}) + +&pager( + (defined($ENV{PAGER}) ? $ENV{PAGER} : ($^O eq 'os2' ? 'cmd /c more' : 'more'))) unless defined $pager; +setman(); &recallCommand("!") unless defined $prc; &shellBang("!") unless defined $psh; $maxtrace = 400 unless defined $maxtrace; -if (-e "/dev/tty") { +if (-e "/dev/tty") { # this is the wrong metric! $rcfile=".perldb"; } else { $rcfile="perldb.ini"; } +# This isn't really safe, because there's a race +# between checking and opening. The solution is to +# open and fstat the handle, but then you have to read and +# eval the contents. But then the silly thing gets +# your lexical scope, which is unfortunately at best. +sub safe_do { + my $file = shift; + + # Just exactly what part of the word "CORE::" don't you understand? + local $SIG{__WARN__}; + local $SIG{__DIE__}; + + unless (is_safe_file($file)) { + CORE::warn <' x $level) . - " "))) { + " "))) + { $single = 0; $signal = 0; $cmd =~ s/\\$/\n/ && do { @@ -511,7 +605,15 @@ EOP push(@hist,$cmd) if length($cmd) > 1; PIPE: { ($i) = split(/\s+/,$cmd); - eval "\$cmd =~ $alias{$i}", print $OUT $@ if $alias{$i}; + #eval "\$cmd =~ $alias{$i}", print $OUT $@ if $alias{$i}; + if ($alias{$i}) { + print STDERR "ALIAS $cmd INTO "; + eval "\$cmd =~ $alias{$i}"; + print "$cmd\n"; + print $OUT $@; + } + $cmd =~ s/^\s+//s; # trim annoying leading whitespace + $cmd =~ s/\s+$//s; # trim annoying trailing whitespace $cmd =~ /^q$/ && ($exiting = 1) && exit 0; $cmd =~ /^h$/ && do { print_help($help); @@ -519,10 +621,14 @@ EOP $cmd =~ /^h\s+h$/ && do { print_help($summary); next CMD; }; - $cmd =~ /^h\s+(\S)$/ && do { - my $asked = "\Q$1"; - if ($help =~ /^(?:[IB]<)$asked/m) { - while ($help =~ /^((?:[IB]<)$asked([\s\S]*?)\n)(?!\s)/mg) { + # support long commands; otherwise bogus errors + # happen when you ask for h on for example + $cmd =~ /^h\s+(\S.*)$/ && do { + my $asked = $1; # for proper errmsg + my $qasked = quotemeta($asked); # for searching + # XXX: finds CR but not + if ($help =~ /^\s*(.*)/ && do { - $post = [], next CMD unless $1; + unless ($1) { + print OUT "All > actions cleared.\n"; + $post = []; + next CMD; + } + if ($1 eq '?') { + unless (@$post) { + print OUT "No post-prompt Perl actions.\n"; + next CMD; + } + print OUT "Perl commands run after each prompt:\n"; + for my $action ( @$post ) { + print "\t> -- $action\n"; + } + next CMD; + } $post = [action($1)]; next CMD; }; $cmd =~ /^\{\{\s*(.*)/ && do { + if ($cmd =~ /^\{.*\}$/ && unbalanced(substr($cmd,2))) { + print OUT "{{ is now a debugger command\n", + "use `;{{' if you mean Perl code\n"; + $cmd = "h {{"; + redo CMD; + } push @$pretype, $1; next CMD; }; $cmd =~ /^\{\s*(.*)/ && do { - $pretype = [], next CMD unless $1; + unless ($1) { + print OUT "All { actions cleared.\n"; + $pretype = []; + next CMD; + } + if ($1 eq '?') { + unless (@$pretype) { + print OUT "No pre-prompt debugger actions.\n"; + next CMD; + } + print OUT "Debugger commands run before each prompt:\n"; + for my $action ( @$pretype ) { + print "\t{ -- $action\n"; + } + next CMD; + } + if ($cmd =~ /^\{.*\}$/ && unbalanced(substr($cmd,1))) { + print OUT "{ is now a debugger command\n", + "use `;{' if you mean Perl code\n"; + $cmd = "h {"; + redo CMD; + } $pretype = [$1]; next CMD; }; $cmd =~ /^a\b\s*(\d*)\s*(.*)/ && do { @@ -957,7 +1124,7 @@ EOP set_list("PERLDB_INC", @ini_INC); if ($0 eq '-e') { for (1..$#{'::_<-e'}) { # The first line is PERL5DB - chomp ($cl = $ {'::_<-e'}[$_]); + chomp ($cl = ${'::_<-e'}[$_]); push @script, '-e', $cl; } } else { @@ -1021,8 +1188,8 @@ EOP set_list("PERLDB_POST", @$post); set_list("PERLDB_TYPEAHEAD", @typeahead); $ENV{PERLDB_RESTART} = 1; - #print "$^X, '-d', @flags, @script, ($emacs ? '-emacs' : ()), @ARGS"; - exec $^X, '-d', @flags, @script, ($emacs ? '-emacs' : ()), @ARGS; + #print "$^X, '-d', @flags, @script, ($slave_editor ? '-emacs' : ()), @ARGS"; + exec $^X, '-d', @flags, @script, ($slave_editor ? '-emacs' : ()), @ARGS; print $OUT "exec failed: $!\n"; last CMD; }; $cmd =~ /^T$/ && do { @@ -1059,7 +1226,7 @@ EOP $start = 1 if ($start > $max); last if ($start == $end); if ($dbline[$start] =~ m' . "\a$pat\a" . 'i) { - if ($emacs) { + if ($slave_editor) { print $OUT "\032\032$filename:$start:0\n"; } else { print $OUT "$start:\t", $dbline[$start], "\n"; @@ -1088,7 +1255,7 @@ EOP $start = $max if ($start <= 0); last if ($start == $end); if ($dbline[$start] =~ m' . "\a$pat\a" . 'i) { - if ($emacs) { + if ($slave_editor) { print $OUT "\032\032$filename:$start:0\n"; } else { print $OUT "$start:\t", $dbline[$start], "\n"; @@ -1124,16 +1291,21 @@ EOP &system($ENV{SHELL}||"/bin/sh"); next CMD; }; $cmd =~ /^$sh\s*([\x00-\xff]*)/ && do { + # XXX: using csh or tcsh destroys sigint retvals! + #&system($1); # use this instead &system($ENV{SHELL}||"/bin/sh","-c",$1); next CMD; }; $cmd =~ /^H\b\s*(-(\d+))?/ && do { - $end = $2?($#hist-$2):0; + $end = $2 ? ($#hist-$2) : 0; $hist = 0 if $hist < 0; for ($i=$#hist; $i>$end; $i--) { print $OUT "$i: ",$hist[$i],"\n" unless $hist[$i] =~ /^.?$/; }; next CMD; }; + $cmd =~ /^(?:man|(?:perl)?doc)\b(?:\s+([^(]*))?$/ && do { + runman($1); + next CMD; }; $cmd =~ s/^p$/print {\$DB::OUT} \$_/; $cmd =~ s/^p\b/print {\$DB::OUT} /; $cmd =~ /^=/ && do { @@ -1157,25 +1329,29 @@ EOP } else { open(SAVEOUT,">&OUT") || &warn("Can't save DB::OUT"); } + fix_less(); unless ($piped=open(OUT,$pager)) { &warn("Can't pipe output to `$pager'"); if ($pager =~ /^\|/) { - open(OUT,">&STDOUT") || &warn("Can't restore DB::OUT"); + open(OUT,">&STDOUT") # XXX: lost message + || &warn("Can't restore DB::OUT"); open(STDOUT,">&SAVEOUT") || &warn("Can't restore STDOUT"); close(SAVEOUT); } else { - open(OUT,">&STDOUT") || &warn("Can't restore DB::OUT"); + open(OUT,">&STDOUT") # XXX: lost message + || &warn("Can't restore DB::OUT"); } next CMD; } $SIG{PIPE}= \&DB::catch if $pager =~ /^\|/ - && "" eq $SIG{PIPE} || "DEFAULT" eq $SIG{PIPE}; + && ("" eq $SIG{PIPE} || "DEFAULT" eq $SIG{PIPE}); $selected= select(OUT); $|= 1; select( $selected ), $selected= "" unless $cmd =~ /^\|\|/; $cmd =~ s/^\|+\s*//; - redo PIPE; }; + redo PIPE; + }; # XXX Local variants do not work! $cmd =~ s/^t\s/\$DB::trace |= 1;\n/; $cmd =~ s/^s\s/\$DB::single = 1;\n/ && do {$laststep = 's'}; @@ -1190,14 +1366,27 @@ EOP } continue { # CMD: if ($piped) { if ($pager =~ /^\|/) { - $?= 0; close(OUT) || &warn("Can't close DB::OUT"); - &warn( "Pager `$pager' failed: ", - ($?>>8) > 128 ? ($?>>8)-256 : ($?>>8), - ( $? & 128 ) ? " (core dumped)" : "", - ( $? & 127 ) ? " (SIG ".($?&127).")" : "", "\n" ) if $?; + $? = 0; + # we cannot warn here: the handle is missing --tchrist + close(OUT) || print SAVEOUT "\nCan't close DB::OUT\n"; + + # most of the $? crud was coping with broken cshisms + if ($?) { + print SAVEOUT "Pager `$pager' failed: "; + if ($? == -1) { + print SAVEOUT "shell returned -1\n"; + } elsif ($? >> 8) { + print SAVEOUT + ( $? & 127 ) ? " (SIG#".($?&127).")" : "", + ( $? & 128 ) ? " -- core dumped" : "", "\n"; + } else { + print SAVEOUT "status ", ($? >> 8), "\n"; + } + } + open(OUT,">&STDOUT") || &warn("Can't restore DB::OUT"); open(STDOUT,">&SAVEOUT") || &warn("Can't restore STDOUT"); - $SIG{PIPE}= "DEFAULT" if $SIG{PIPE} eq \&DB::catch; + $SIG{PIPE} = "DEFAULT" if $SIG{PIPE} eq \&DB::catch; # Will stop ignoring SIGPIPE if done like nohup(1) # does SIGINT but Perl doesn't give us a choice. } else { @@ -1282,7 +1471,9 @@ sub save { # The following takes its argument via $evalarg to preserve current @_ sub eval { - local @res; # 'my' would make it visible from user code + # 'my' would make it visible from user code + # but so does local! --tchrist + local @res; { local $otrace = $trace; local $osingle = $single; @@ -1347,7 +1538,7 @@ sub postponed { #%dbline = %{$postponed_file{$filename}}; # Cannot be done: unsufficient magic my $key; for $key (keys %{$postponed_file{$filename}}) { - $dbline{$key} = $ {$postponed_file{$filename}}{$key}; + $dbline{$key} = ${$postponed_file{$filename}}{$key}; } delete $postponed_file{$filename}; } @@ -1463,6 +1654,20 @@ sub action { $action; } +sub unbalanced { + # i hate using globals! + $balanced_brace_re ||= qr{ + ^ \{ + (?: + (?> [^{}] + ) # Non-parens without backtracking + | + (??{ $balanced_brace_re }) # Group with matching parens + ) * + \} $ + }x; + return $_[0] !~ m/$balanced_brace_re/; +} + sub gets { local($.); #; @@ -1471,19 +1676,30 @@ sub gets { sub system { # We save, change, then restore STDIN and STDOUT to avoid fork() since - # many non-Unix systems can do system() but have problems with fork(). + # some non-Unix systems can do system() but have problems with fork(). open(SAVEIN,"<&STDIN") || &warn("Can't save STDIN"); open(SAVEOUT,">&STDOUT") || &warn("Can't save STDOUT"); open(STDIN,"<&IN") || &warn("Can't redirect STDIN"); open(STDOUT,">&OUT") || &warn("Can't redirect STDOUT"); + + # XXX: using csh or tcsh destroys sigint retvals! system(@_); open(STDIN,"<&SAVEIN") || &warn("Can't restore STDIN"); open(STDOUT,">&SAVEOUT") || &warn("Can't restore STDOUT"); - close(SAVEIN); close(SAVEOUT); - &warn( "(Command returned ", ($?>>8) > 128 ? ($?>>8)-256 : ($?>>8), ")", - ( $? & 128 ) ? " (core dumped)" : "", - ( $? & 127 ) ? " (SIG ".($?&127).")" : "", "\n" ) if $?; - $?; + close(SAVEIN); + close(SAVEOUT); + + + # most of the $? crud was coping with broken cshisms + if ($? >> 8) { + &warn("(Command exited ", ($? >> 8), ")\n"); + } elsif ($?) { + &warn( "(Command died of SIG#", ($? & 127), + (($? & 128) ? " -- core dumped" : "") , ")", "\n"); + } + + return $?; + } sub setterm { @@ -1572,7 +1788,7 @@ sub readline { if (ref $OUT and UNIVERSAL::isa($OUT, 'IO::Socket::INET')) { print $OUT @_; my $stuff; - $IN->recv( $stuff, 2048 ); + $IN->recv( $stuff, 2048 ); # XXX: what's wrong with sysread? $stuff; } else { @@ -1591,15 +1807,15 @@ sub option_val { my ($opt, $default)= @_; my $val; if (defined $optionVars{$opt} - and defined $ {$optionVars{$opt}}) { - $val = $ {$optionVars{$opt}}; + and defined ${$optionVars{$opt}}) { + $val = ${$optionVars{$opt}}; } elsif (defined $optionAction{$opt} and defined &{$optionAction{$opt}}) { $val = &{$optionAction{$opt}}(); } elsif (defined $optionAction{$opt} and not defined $option{$opt} or defined $optionVars{$opt} - and not defined $ {$optionVars{$opt}}) { + and not defined ${$optionVars{$opt}}) { $val = $default; } else { $val = $option{$opt}; @@ -1609,8 +1825,16 @@ sub option_val { sub parse_options { local($_)= @_; - while ($_ ne "") { - s/^(\w+)(\s*$|\W)// or print($OUT "Invalid option `$_'\n"), last; + # too dangerous to let intuitive usage overwrite important things + # defaultion should never be the default + my %opt_needs_val = map { ( $_ => 1 ) } qw{ + arrayDepth hashDepth LineInfo maxTraceLen noTTY ornaments + pager quote ReadLine recallCommand RemotePort ShellBang TTY + }; + while (length) { + my $val_defaulted; + s/^\s+// && next; + s/^(\w+)(\W?)// or print($OUT "Invalid option `$_'\n"), last; my ($opt,$sep) = ($1,$2); my $val; if ("?" eq $sep) { @@ -1618,59 +1842,83 @@ sub parse_options { if /^\S/; #&dump_option($opt); } elsif ($sep !~ /\S/) { - $val = "1"; + $val_defaulted = 1; + $val = "1"; # this is an evil default; make 'em set it! } elsif ($sep eq "=") { - s/^(\S*)($|\s+)//; + + if (s/ (["']) ( (?: \\. | (?! \1 ) [^\\] )* ) \1 //x) { + my $quote = $1; + ($val = $2) =~ s/\\([$quote\\])/$1/g; + } else { + s/^(\S*)//; $val = $1; + print OUT qq(Option better cleared using $opt=""\n) + unless length $val; + } + } else { #{ to "let some poor schmuck bounce on the % key in B." my ($end) = "\\" . substr( ")]>}$sep", index("([<{",$sep), 1 ); #} s/^(([^\\$end]|\\[\\$end])*)$end($|\s+)// or print($OUT "Unclosed option value `$opt$sep$_'\n"), last; - $val = $1; - $val =~ s/\\([\\$end])/$1/g; + ($val = $1) =~ s/\\([\\$end])/$1/g; } - my ($option); - my $matches = - grep( /^\Q$opt/ && ($option = $_), @options ); - $matches = grep( /^\Q$opt/i && ($option = $_), @options ) - unless $matches; - print $OUT "Unknown option `$opt'\n" unless $matches; - print $OUT "Ambiguous option `$opt'\n" if $matches > 1; - $option{$option} = $val if $matches == 1 and defined $val; - eval "local \$frame = 0; local \$doret = -2; - require '$optionRequire{$option}'" - if $matches == 1 and defined $optionRequire{$option} and defined $val; - $ {$optionVars{$option}} = $val - if $matches == 1 - and defined $optionVars{$option} and defined $val; - & {$optionAction{$option}} ($val) - if $matches == 1 - and defined $optionAction{$option} - and defined &{$optionAction{$option}} and defined $val; - &dump_option($option) if $matches == 1 && $OUT ne \*STDERR; # Not $rcfile - s/^\s+//; + + my $option; + my $matches = grep( /^\Q$opt/ && ($option = $_), @options ) + || grep( /^\Q$opt/i && ($option = $_), @options ); + + print($OUT "Unknown option `$opt'\n"), next unless $matches; + print($OUT "Ambiguous option `$opt'\n"), next if $matches > 1; + + if ($opt_needs_val{$option} && $val_defaulted) { + print $OUT "Option `$opt' is non-boolean. Use `O $option=VAL' to set, `O $option?' to query\n"; + next; + } + + $option{$option} = $val if defined $val; + + eval qq{ + local \$frame = 0; + local \$doret = -2; + require '$optionRequire{$option}'; + 1; + } || die # XXX: shouldn't happen + if defined $optionRequire{$option} && + defined $val; + + ${$optionVars{$option}} = $val + if defined $optionVars{$option} && + defined $val; + + &{$optionAction{$option}} ($val) + if defined $optionAction{$option} && + defined &{$optionAction{$option}} && + defined $val; + + # Not $rcfile + dump_option($option) unless $OUT eq \*STDERR; } } sub set_list { my ($stem,@list) = @_; my $val; - $ENV{"$ {stem}_n"} = @list; + $ENV{"${stem}_n"} = @list; for $i (0 .. $#list) { $val = $list[$i]; $val =~ s/\\/\\\\/g; $val =~ s/([\0-\37\177\200-\377])/"\\0x" . unpack('H2',$1)/eg; - $ENV{"$ {stem}_$i"} = $val; + $ENV{"${stem}_$i"} = $val; } } sub get_list { my $stem = shift; my @list; - my $n = delete $ENV{"$ {stem}_n"}; + my $n = delete $ENV{"${stem}_n"}; my $val; for $i (0 .. $n - 1) { - $val = delete $ENV{"$ {stem}_$i"}; + $val = delete $ENV{"${stem}_$i"}; $val =~ s/\\((\\)|0x(..))/ $2 ? $2 : pack('H2', $3) /ge; push @list, $val; } @@ -1734,7 +1982,7 @@ sub RemotePort { } sub tkRunning { - if ($ {$term->Features}{tkRunning}) { + if (${$term->Features}{tkRunning}) { return $term->tkRunning(@_); } else { print $OUT "tkRunning not supported by current ReadLine package.\n"; @@ -1796,7 +2044,7 @@ sub LineInfo { return $lineinfo unless @_; $lineinfo = shift; my $stream = ($lineinfo =~ /^(\+?\>|\|)/) ? $lineinfo : ">$lineinfo"; - $emacs = ($stream =~ /^\|/); + $slave_editor = ($stream =~ /^\|/); open(LINEINFO, "$stream") || &warn("Cannot open `$stream' for write"); $LINEINFO = \*LINEINFO; my $save = select($LINEINFO); @@ -1814,8 +2062,8 @@ sub list_versions { s,/,::,g ; s/^perl5db$/DB/; s/^Term::ReadLine::readline$/readline/; - if (defined $ { $_ . '::VERSION' }) { - $version{$file} = "$ { $_ . '::VERSION' } from "; + if (defined ${ $_ . '::VERSION' }) { + $version{$file} = "${ $_ . '::VERSION' } from "; } $version{$file} .= $INC{$file}; } @@ -1823,6 +2071,10 @@ sub list_versions { } sub sethelp { + # XXX: make sure these are tabs between the command and explantion, + # or print_help will screw up your formatting if you have + # eeevil ornaments enabled. This is an insane mess. + $help = " B Stack trace. B [I] Single step [in I]. @@ -1884,39 +2136,16 @@ B I Evals expression in array context, dumps the result. B I Evals expression in array context, prints methods callable on the first element of the result. B I Prints methods callable via the given class. -B [I[B<=>I]] [IB<\">IB<\">] [IB]... - Set or query values of options. I defaults to 1. I can - be abbreviated. Several options can be listed. - I, I: chars used to recall command or spawn shell; - I: program for output of \"|cmd\"; - I: run Tk while prompting (with ReadLine); - I I I: level of verbosity; - I Allows stepping off the end of the script. - I Debugger should stop as early as possible. - I: Remote hostname:port for remote debugging - The following options affect what happens with B, B, and B commands: - I, I: print only first N elements ('' for all); - I, I: change style of array and hash dump; - I: whether to print contents of globs; - I: dump arrays holding debugged files; - I: dump symbol tables of packages; - I: dump contents of \"reused\" addresses; - I, I, I: change style of string dump; - I: Do not print the overload-stringified value; - Option I affects printing of return value after B command, - I affects printing messages on entry and exit from subroutines. - I affects printing messages on every possible breaking point. - I gives maximal length of evals/args listed in stack trace. - I affects screen appearance of the command line. - During startup options are initialized from \$ENV{PERLDB_OPTS}. - You can put additional initialization options I, I, - I, I, and I there (or use - `B' after you set them). + +B<<> ? List Perl commands to run before each prompt. B<<> I Define Perl command to run before each prompt. B<<<> I Add to the list of Perl commands to run before each prompt. +B<>> ? List Perl commands to run after each prompt. B<>> I Define Perl command to run after each prompt. B<>>B<>> I Add to the list of Perl commands to run after each prompt. B<{> I Define debugger command to run before each prompt. +B<{> ? List debugger commands to run before each prompt. +B<<> I Define Perl command to run before each prompt. B<{{> I Add to the list of debugger commands to run before each prompt. B<$prc> I Redo a previous command (default previous command). B<$prc> I<-number> Redo number'th-to-last command. @@ -1938,13 +2167,49 @@ B Pure-man-restart of debugger, some of debugger state Currently the following setting are preserved: history, breakpoints and actions, debugger Bptions and the following command-line options: I<-w>, I<-I>, I<-e>. + +B [I] ... Set boolean option to true +B [IB] Query options +B [IB<=>I] [I=B<\">IB<\">] ... + Set options. Use quotes in spaces in value. + I, I chars used to recall command or spawn shell; + I program for output of \"|cmd\"; + I run Tk while prompting (with ReadLine); + I I I level of verbosity; + I Allows stepping off the end of the script. + I Debugger should stop as early as possible. + I Remote hostname:port for remote debugging + The following options affect what happens with B, B, and B commands: + I, I print only first N elements ('' for all); + I, I change style of array and hash dump; + I whether to print contents of globs; + I dump arrays holding debugged files; + I dump symbol tables of packages; + I dump contents of \"reused\" addresses; + I, I, I change style of string dump; + I Do not print the overload-stringified value; + Other options include: + I affects printing of return value after B command, + I affects printing messages on entry and exit from subroutines. + I affects printing messages on every possible breaking point. + I gives maximal length of evals/args listed in stack trace. + I affects screen appearance of the command line. + During startup options are initialized from \$ENV{PERLDB_OPTS}. + You can put additional initialization options I, I, + I, I, and I there (or use + `B' after you set them). + +B or B<^D> Quit. Set B<\$DB::finished = 0> to debug global destruction. B [I] Get help [on a specific debugger command], enter B<|h> to page. - Complete description of debugger is available in B - section of Perl documention B Summary of debugger commands. -B or B<^D> Quit. Set B<\$DB::finished = 0> to debug global destruction. +B<$doccmd> I Runs the external doc viewer B<$doccmd> command on the + named Perl I, or on B<$doccmd> itself if omitted. + Set B<\$DB::doccmd> to change viewer. + +Type `|h' for a paged display if this was too hard to read. + +"; # Fix balance of vi % matching: } }} -"; $summary = <<"END_SUM"; I I B [I|I] List source code B Stack trace @@ -1968,18 +2233,71 @@ I B Execute perl code, also see: B,B,B< B [[B]I] List subroutine names [not] matching pattern B [I [I]] List Variables in Package. Vars can be ~pattern or !pattern. B [I] Same as \"B I [I]\". -I BI<:> Type B I Run B for more help. +For more help, type B I, or run B<$doccmd perldebug> for all docs. END_SUM - # ')}}; # Fix balance of Emacs parsing + # ')}}; # Fix balance of vi % matching } sub print_help { - my $message = shift; - if (@Term::ReadLine::TermCap::rl_term_set) { - $message =~ s/B<([^>]+|>)>/$Term::ReadLine::TermCap::rl_term_set[2]$1$Term::ReadLine::TermCap::rl_term_set[3]/g; - $message =~ s/I<([^>]+|>)>/$Term::ReadLine::TermCap::rl_term_set[0]$1$Term::ReadLine::TermCap::rl_term_set[1]/g; - } - print $OUT $message; + local $_ = shift; + + # Restore proper alignment destroyed by eeevil I<> and B<> + # ornaments: A pox on both their houses! + # + # A help command will have everything up to and including + # the first tab sequence paddeed into a field 16 (or if indented 20) + # wide. If it's wide than that, an extra space will be added. + s{ + ^ # only matters at start of line + ( \040{4} | \t )* # some subcommands are indented + ( < ? # so works + [BI] < [^\t\n] + ) # find an eeevil ornament + ( \t+ ) # original separation, discarded + ( .* ) # this will now start (no earlier) than + # column 16 + } { + my($leadwhite, $command, $midwhite, $text) = ($1, $2, $3, $4); + my $clean = $command; + $clean =~ s/[BI]<([^>]*)>/$1/g; + # replace with this whole string: + (length($leadwhite) ? " " x 4 : "") + . $command + . ((" " x (16 + (length($leadwhite) ? 4 : 0) - length($clean))) || " ") + . $text; + + }mgex; + + s{ # handle bold ornaments + B < ( [^>] + | > ) > + } { + $Term::ReadLine::TermCap::rl_term_set[2] + . $1 + . $Term::ReadLine::TermCap::rl_term_set[3] + }gex; + + s{ # handle italic ornaments + I < ( [^>] + | > ) > + } { + $Term::ReadLine::TermCap::rl_term_set[0] + . $1 + . $Term::ReadLine::TermCap::rl_term_set[1] + }gex; + + print $OUT $_; +} + +sub fix_less { + return if defined $ENV{LESS} && $ENV{LESS} =~ /r/; + my $is_less = $pager =~ /\bless\b/; + if ($pager =~ /\bmore\b/) { + my @st_more = stat('/usr/bin/more'); + my @st_less = stat('/usr/bin/less'); + $is_less = @st_more && @st_less + && $st_more[0] == $st_less[0] + && $st_more[1] == $st_less[1]; + } + # changes environment! + $ENV{LESS} .= 'r' if $is_less; } sub diesignal { @@ -2030,8 +2348,10 @@ sub dbdie { } eval { require Carp } if defined $^S; # If error/warning during compilation, # require may be broken. + die(@_, "\nCannot print stack trace, load with -MCarp option to see stack") unless defined &Carp::longmess; + # We do not want to debug this chunk (automatic disabling works # inside DB::DB, but not in Carp). my ($mysingle,$mytrace) = ($single,$trace); @@ -2138,18 +2458,81 @@ sub methods_via { my $prefix = shift; my $prepend = $prefix ? "via $prefix: " : ''; my $name; - for $name (grep {defined &{$ {"$ {class}::"}{$_}}} - sort keys %{"$ {class}::"}) { + for $name (grep {defined &{${"${class}::"}{$_}}} + sort keys %{"${class}::"}) { next if $seen{ $name }++; print $DB::OUT "$prepend$name\n"; } return unless shift; # Recurse? - for $name (@{"$ {class}::ISA"}) { + for $name (@{"${class}::ISA"}) { $prepend = $prefix ? $prefix . " -> $name" : $name; methods_via($name, $prepend, 1); } } +sub setman { + $doccmd = $^O !~ /^(?:MSWin32|VMS|os2|dos|amigaos|riscos|MacOS)\z/s + ? "man" # O Happy Day! + : "perldoc"; # Alas, poor unfortunates +} + +sub runman { + my $page = shift; + unless ($page) { + &system("$doccmd $doccmd"); + return; + } + # this way user can override, like with $doccmd="man -Mwhatever" + # or even just "man " to disable the path check. + unless ($doccmd eq 'man') { + &system("$doccmd $page"); + return; + } + + $page = 'perl' if lc($page) eq 'help'; + + require Config; + my $man1dir = $Config::Config{'man1dir'}; + my $man3dir = $Config::Config{'man3dir'}; + for ($man1dir, $man3dir) { s#/[^/]*\z## if /\S/ } + my $manpath = ''; + $manpath .= "$man1dir:" if $man1dir =~ /\S/; + $manpath .= "$man3dir:" if $man3dir =~ /\S/ && $man1dir ne $man3dir; + chop $manpath if $manpath; + # harmless if missing, I figure + my $oldpath = $ENV{MANPATH}; + $ENV{MANPATH} = $manpath if $manpath; + my $nopathopt = $^O =~ /dunno what goes here/; + if (system($doccmd, + # I just *know* there are men without -M + (($manpath && !$nopathopt) ? ("-M", $manpath) : ()), + split ' ', $page) ) + { + unless ($page =~ /^perl\w/) { + if (grep { $page eq $_ } qw{ + 5004delta 5005delta amiga api apio book boot bot call compile + cygwin data dbmfilter debug debguts delta diag doc dos dsc embed + faq faq1 faq2 faq3 faq4 faq5 faq6 faq7 faq8 faq9 filter fork + form func guts hack hist hpux intern ipc lexwarn locale lol mod + modinstall modlib number obj op opentut os2 os390 pod port + ref reftut run sec style sub syn thrtut tie toc todo toot tootc + trap unicode var vms win32 xs xstut + }) + { + $page =~ s/^/perl/; + system($doccmd, + (($manpath && !$nopathopt) ? ("-M", $manpath) : ()), + $page); + } + } + } + if (defined $oldpath) { + $ENV{MANPATH} = $manpath; + } else { + delete $ENV{MANPATH}; + } +} + # The following BEGIN is very handy if debugger goes havoc, debugging debugger? BEGIN { # This does not compile, alas. @@ -2187,7 +2570,7 @@ sub db_complete { # Specific code for b c l V m f O, &blah, $blah, @blah, %blah my($text, $line, $start) = @_; my ($itext, $search, $prefix, $pack) = - ($text, "^\Q$ {'package'}::\E([^:]+)\$"); + ($text, "^\Q${'package'}::\E([^:]+)\$"); return sort grep /^\Q$text/, (keys %sub), qw(postpone load compile), # subroutines (map { /$search/ ? ($1) : () } keys %sub) diff --git a/pod/perl.pod b/pod/perl.pod index f90696e..221f7f4 100644 --- a/pod/perl.pod +++ b/pod/perl.pod @@ -69,6 +69,7 @@ sections: perlembed Perl ways to embed perl in your C or C++ application perlapio Perl internal IO abstraction interface + perldebguts Perl debugging guts and tips perlxs Perl XS application programming interface perlxstut Perl XS tutorial perlguts Perl internal functions for those doing extensions @@ -222,148 +223,8 @@ Okay, that's I enough hype. =head1 AVAILABILITY Perl is available for most operating systems, including virtually -all Unix-like platforms. - -As of early March 2000 (the Perl release 5.6.0), the following -platforms are able to build Perl from the standard source code -distribution available at http://www.perl.com/CPAN/src/index.html - - AIX - DOS DJGPP 1) - FreeBSD - HP-UX - IRIX - Linux - LynxOS - MachTen - MPE/iX - NetBSD - OpenBSD - OS/2 - Rhapsody/Darwin 2) - Solaris - Tru64 UNIX 3) - UNICOS - UNICOS/mk - VMS - VOS - Windows 3.1 1) - Windows 95 1) 4) - Windows 98 1) 4) - Windows NT 1) 4) - - 1) in DOS mode either the DOS or OS/2 ports can be used - 2) new in 5.6.0: the BSD/NeXT-based UNIX of Mac OS X - 3) formerly known as Digital UNIX and before that DEC OSF/1 - 4) compilers: Borland, Cygwin, Mingw32 EGCS/GCC, VC++ - -The following platforms worked for the previous major release -(5.005_03 being the latest maintenance release of that, as of early -March 2000), but be did not manage to test these in time for the 5.6.0 -release of Perl. There is a very good chance that these will work -just fine with 5.6.0. - - A/UX - BeOS - BSD/OS - DG/UX - DYNIX/ptx - DomainOS - Hurd - NextSTEP - OpenSTEP - PowerMAX - QNX - SCO ODT/OSR - SunOS - SVR4 - Ultrix - -The following platform worked for the previous major release (5.005_03 -being the latest maintenance release of that, as of early March 2000). -However, standardization on UTF-8 as the internal string representation -in 5.6.0 has introduced incompatibilities in this EBCDIC platform. -Support for this platform may be enabled in a future release: - - OS390 1) - - 1) Previously known as MVS, or OpenEdition MVS. - -Strongly related to the OS390 platform by also being EBCDIC-based -mainframe platforms are the following platforms: - - BS2000 - VM/ESA - -These are also not expected to work under 5.6.0 for the same reasons -as OS390. Contact the mailing list perl-mvs@perl.org for more details. - -MacOS (Classic, pre-X) is almost 5.6.0-ready; building from the source -does work with 5.6.0, but additional MacOS specific source code is needed -for a complete port. Contact the mailing list macperl-porters@macperl.org -for more more information. - -The following platforms have been known to build Perl from source in -the past, but we haven't been able to verify their status for the -current release, either because the hardware/software platforms are -rare or because we don't have an active champion on these -platforms--or both: - - 3b1 - AmigaOS - ConvexOS - CX/UX - DC/OSx - DDE SMES - DOS EMX - Dynix - EP/IX - ESIX - FPS - GENIX - Greenhills - ISC - MachTen 68k - MiNT - MPC - NEWS-OS - Opus - Plan 9 - PowerUX - RISC/os - Stellar - SVR2 - TI1500 - TitanOS - Unisys Dynix - Unixware - -Support for the following platform is planned for a future Perl release: - - Netware - -The following platforms have their own source code distributions and -binaries available via http://www.perl.com/CPAN/ports/index.html: - - Perl release - - AS/400 5.003 - Netware 5.003_07 - Tandem Guardian 5.004 - -The following platforms have only binaries available via -http://www.perl.com/CPAN/ports/index.html: - - Perl release - - Acorn RISCOS 5.005_02 - AOS 5.002 - LynxOS 5.004_02 - -Although we do suggest that you always build your own Perl from -the source code, both for maximal configurability and for security, -in case you are in a hurry you can check -http://www.perl.com/CPAN/ports/index.html for binary distributions. +all Unix-like platforms. See L +for a listing. =head1 ENVIRONMENT @@ -432,7 +293,7 @@ affected by wraparound). You may mail your bug reports (be sure to include full configuration information as output by the myconfig program in the perl source tree, or by C) to perlbug@perl.com . If you've succeeded -in compiling perl, the perlbug script in the utils/ subdirectory +in compiling perl, the B script in the F subdirectory can be used to help mail in a bug report. Perl actually stands for Pathologically Eclectic Rubbish Lister, but diff --git a/pod/perldebguts.pod b/pod/perldebguts.pod new file mode 100644 index 0000000..b74f3ef --- /dev/null +++ b/pod/perldebguts.pod @@ -0,0 +1,923 @@ +=head1 NAME + +perldebguts - Guts of Perl debugging + +=head1 DESCRIPTION + +This is not the perldebug(1) manpage, which tells you how to use +the debugger. This manpage describes low-level details ranging +between difficult and impossible for anyone who isn't incredibly +intimate with Perl's guts to understand. Caveat lector. + +=head1 Debugger Internals + +Perl has special debugging hooks at compile-time and run-time used +to create debugging environments. These hooks are not to be confused +with the I command described in L, which are +usable only if a special Perl built per the instructions the +F podpage in the Perl source tree. + +For example, whenever you call Perl's built-in C function +from the package DB, the arguments that the corresponding stack +frame was called with are copied to the the @DB::args array. The +general mechanisms is enabled by calling Perl with the B<-d> switch, the +following additional features are enabled (cf. L): + +=over + +=item * + +Perl inserts the contents of C<$ENV{PERL5DB}> (or C if not present) before the first line of your program. + +=item * + +The array C<@{"_<$filename"}> holds the lines of $filename for all +files compiled by Perl. The same for Ced strings that contain +subroutines, or which are currently being executed. The $filename +for Ced strings looks like C<(eval 34)>. Code assertions +in regexes look like C<(re_eval 19)>. + +=item * + +The hash C<%{"_<$filename"}> contains breakpoints and actions keyed +by line number. Individual entries (as opposed to the whole hash) +are settable. Perl only cares about Boolean true here, although +the values used by F have the form +C<"$break_condition\0$action">. Values in this hash are magical +in numeric context: they are zeros if the line is not breakable. + +The same holds for evaluated strings that contain subroutines, or +which are currently being executed. The $filename for Ced strings +looks like C<(eval 34)> or C<(re_eval 19)>. + +=item * + +The scalar C<${"_<$filename"}> contains C<"_<$filename">. This is +also the case for evaluated strings that contain subroutines, or +which are currently being executed. The $filename for Ced +strings looks like C<(eval 34)> or C<(re_eval 19)>. + +=item * + +After each Cd file is compiled, but before it is executed, +C is called if the subroutine +C exists. Here, the $filename is the expanded name of +the Cd file, as found in the values of %INC. + +=item * + +After each subroutine C is compiled, the existence of +C<$DB::postponed{subname}> is checked. If this key exists, +C is called if the C subroutine +also exists. + +=item * + +A hash C<%DB::sub> is maintained, whose keys are subroutine names +and whose values have the form C. +C has the form C<(eval 34)> for subroutines defined inside +Cs, or C<(re_eval 19)> for those within regex code assertions. + +=item * + +When the execution of your program reaches a point that can hold a +breakpoint, the C subroutine is called any of the variables +$DB::trace, $DB::single, or $DB::signal is true. These variables +are not Cizable. This feature is disabled when executing +inside C, including functions called from it +unless C<< $^D & (1<<30) >> is true. + +=item * + +When execution of the program reaches a subroutine call, a call to +C<&DB::sub>(I) is made instead, with C<$DB::sub> holding the +name of the called subroutine. This doesn't happen if the subroutine +was compiled in the C package.) + +=back + +Note that if C<&DB::sub> needs external data for it to work, no +subroutine call is possible until this is done. For the standard +debugger, the C<$DB::deep> variable (how many levels of recursion +deep into the debugger you can go before a mandatory break) gives +an example of such a dependency. + +=head2 Writing Your Own Debugger + +The minimal working debugger consists of one line + + sub DB::DB {} + +which is quite handy as contents of C environment +variable: + + $ PERL5DB="sub DB::DB {}" perl -d your-script + +Another brief debugger, slightly more useful, could be created +with only the line: + + sub DB::DB {print ++$i; scalar } + +This debugger would print the sequential number of encountered +statement, and would wait for you to hit a newline before continuing. + +The following debugger is quite functional: + + { + package DB; + sub DB {} + sub sub {print ++$i, " $sub\n"; &$sub} + } + +It prints the sequential number of subroutine call and the name of the +called subroutine. Note that C<&DB::sub> should be compiled into the +package C. + +At the start, the debugger reads your rc file (F<./.perldb> or +F<~/.perldb> under Unix), which can set important options. This file may +define a subroutine C<&afterinit> to be executed after the debugger is +initialized. + +After the rc file is read, the debugger reads the PERLDB_OPTS +environment variable and parses this as the remainder of a C +line as one might enter at the debugger prompt. + +The debugger also maintains magical internal variables, such as +C<@DB::dbline>, C<%DB::dbline>, which are aliases for +C<@{"::_ C<%{"::_. Here C +is the currently selected file, either explicitly chosen with the +debugger's C command, or implicitly by flow of execution. + +Some functions are provided to simplify customization. See +L for description of options parsed by +C. The function C skips the specified number of frames and returns a list +containing information about the calling frames (all of them, if +C is missing). Each entry is reference to a a hash with +keys C (either C<.>, C<$>, or C<@>), C (subroutine +name, or info about C), C (C or a reference to +an array), C, and C. + +The function C prints +formatted info about caller frames. The last two functions may be +convenient as arguments to C<< < >>, C<< << >> commands. + +Note that any variables and functions that are not documented in +this manpages (or in L) are considered for internal +use only, and as such are subject to change without notice. + +=head1 Frame Listing Output Examples + +The C option can be used to control the output of frame +information. For example, contrast this expression trace: + + $ perl -de 42 + Stack dump during die enabled outside of evals. + + Loading DB routines from perl5db.pl patch level 0.94 + Emacs support available. + + Enter h or `h h' for help. + + main::(-e:1): 0 + DB<1> sub foo { 14 } + + DB<2> sub bar { 3 } + + DB<3> t print foo() * bar() + main::((eval 172):3): print foo() + bar(); + main::foo((eval 168):2): + main::bar((eval 170):2): + 42 + +with this one, once the Cption C has been set: + + DB<4> O f=2 + frame = '2' + DB<5> t print foo() * bar() + 3: foo() * bar() + entering main::foo + 2: sub foo { 14 }; + exited main::foo + entering main::bar + 2: sub bar { 3 }; + exited main::bar + 42 + +By way of demonstration, we present below a laborious listing +resulting from setting your C environment variable to +the value C, and running I from the command line. +Examples use various values of C are shown to give you a feel +for the difference between settings. Long those it may be, this +is not a complete listing, but only excerpts. + +=over 4 + +=item 1 + + entering main::BEGIN + entering Config::BEGIN + Package lib/Exporter.pm. + Package lib/Carp.pm. + Package lib/Config.pm. + entering Config::TIEHASH + entering Exporter::import + entering Exporter::export + entering Config::myconfig + entering Config::FETCH + entering Config::FETCH + entering Config::FETCH + entering Config::FETCH + +=item 2 + + entering main::BEGIN + entering Config::BEGIN + Package lib/Exporter.pm. + Package lib/Carp.pm. + exited Config::BEGIN + Package lib/Config.pm. + entering Config::TIEHASH + exited Config::TIEHASH + entering Exporter::import + entering Exporter::export + exited Exporter::export + exited Exporter::import + exited main::BEGIN + entering Config::myconfig + entering Config::FETCH + exited Config::FETCH + entering Config::FETCH + exited Config::FETCH + entering Config::FETCH + +=item 4 + + in $=main::BEGIN() from /dev/null:0 + in $=Config::BEGIN() from lib/Config.pm:2 + Package lib/Exporter.pm. + Package lib/Carp.pm. + Package lib/Config.pm. + in $=Config::TIEHASH('Config') from lib/Config.pm:644 + in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0 + in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from li + in @=Config::myconfig() from /dev/null:0 + in $=Config::FETCH(ref(Config), 'package') from lib/Config.pm:574 + in $=Config::FETCH(ref(Config), 'baserev') from lib/Config.pm:574 + in $=Config::FETCH(ref(Config), 'PERL_VERSION') from lib/Config.pm:574 + in $=Config::FETCH(ref(Config), 'PERL_SUBVERSION') from lib/Config.pm:574 + in $=Config::FETCH(ref(Config), 'osname') from lib/Config.pm:574 + in $=Config::FETCH(ref(Config), 'osvers') from lib/Config.pm:574 + +=item 6 + + in $=main::BEGIN() from /dev/null:0 + in $=Config::BEGIN() from lib/Config.pm:2 + Package lib/Exporter.pm. + Package lib/Carp.pm. + out $=Config::BEGIN() from lib/Config.pm:0 + Package lib/Config.pm. + in $=Config::TIEHASH('Config') from lib/Config.pm:644 + out $=Config::TIEHASH('Config') from lib/Config.pm:644 + in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0 + in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/ + out $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/ + out $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0 + out $=main::BEGIN() from /dev/null:0 + in @=Config::myconfig() from /dev/null:0 + in $=Config::FETCH(ref(Config), 'package') from lib/Config.pm:574 + out $=Config::FETCH(ref(Config), 'package') from lib/Config.pm:574 + in $=Config::FETCH(ref(Config), 'baserev') from lib/Config.pm:574 + out $=Config::FETCH(ref(Config), 'baserev') from lib/Config.pm:574 + in $=Config::FETCH(ref(Config), 'PERL_VERSION') from lib/Config.pm:574 + out $=Config::FETCH(ref(Config), 'PERL_VERSION') from lib/Config.pm:574 + in $=Config::FETCH(ref(Config), 'PERL_SUBVERSION') from lib/Config.pm:574 + +=item 14 + + in $=main::BEGIN() from /dev/null:0 + in $=Config::BEGIN() from lib/Config.pm:2 + Package lib/Exporter.pm. + Package lib/Carp.pm. + out $=Config::BEGIN() from lib/Config.pm:0 + Package lib/Config.pm. + in $=Config::TIEHASH('Config') from lib/Config.pm:644 + out $=Config::TIEHASH('Config') from lib/Config.pm:644 + in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0 + in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/E + out $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/E + out $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0 + out $=main::BEGIN() from /dev/null:0 + in @=Config::myconfig() from /dev/null:0 + in $=Config::FETCH('Config=HASH(0x1aa444)', 'package') from lib/Config.pm:574 + out $=Config::FETCH('Config=HASH(0x1aa444)', 'package') from lib/Config.pm:574 + in $=Config::FETCH('Config=HASH(0x1aa444)', 'baserev') from lib/Config.pm:574 + out $=Config::FETCH('Config=HASH(0x1aa444)', 'baserev') from lib/Config.pm:574 + +=item 30 + + in $=CODE(0x15eca4)() from /dev/null:0 + in $=CODE(0x182528)() from lib/Config.pm:2 + Package lib/Exporter.pm. + out $=CODE(0x182528)() from lib/Config.pm:0 + scalar context return from CODE(0x182528): undef + Package lib/Config.pm. + in $=Config::TIEHASH('Config') from lib/Config.pm:628 + out $=Config::TIEHASH('Config') from lib/Config.pm:628 + scalar context return from Config::TIEHASH: empty hash + in $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0 + in $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/Exporter.pm:171 + out $=Exporter::export('Config', 'main', 'myconfig', 'config_vars') from lib/Exporter.pm:171 + scalar context return from Exporter::export: '' + out $=Exporter::import('Config', 'myconfig', 'config_vars') from /dev/null:0 + scalar context return from Exporter::import: '' + +=back + +In all cases shown above, the line indentation shows the call tree. +If bit 2 of C is set, a line is printed on exit from a +subroutine as well. If bit 4 is set, the arguments are printed +along with the caller info. If bit 8 is set, the arguments are +printed even if they are tied or references. If bit 16 is set, the +return value is printed, too. + +When a package is compiled, a line like this + + Package lib/Carp.pm. + +is printed with proper indentation. + +=head1 Debugging regular expressions + +There are two ways to enable debugging output for regular expressions. + +If your perl is compiled with C<-DDEBUGGING>, you may use the +B<-Dr> flag on the command line. + +Otherwise, one can C, which has effects at +compile time and run time. It is not lexically scoped. + +=head2 Compile-time output + +The debugging output at compile time looks like this: + + compiling RE `[bc]d(ef*g)+h[ij]k$' + size 43 first at 1 + 1: ANYOF(11) + 11: EXACT (13) + 13: CURLYX {1,32767}(27) + 15: OPEN1(17) + 17: EXACT (19) + 19: STAR(22) + 20: EXACT (0) + 22: EXACT (24) + 24: CLOSE1(26) + 26: WHILEM(0) + 27: NOTHING(28) + 28: EXACT (30) + 30: ANYOF(40) + 40: EXACT (42) + 42: EOL(43) + 43: END(0) + anchored `de' at 1 floating `gh' at 3..2147483647 (checking floating) + stclass `ANYOF' minlen 7 + +The first line shows the pre-compiled form of the regex. The second +shows the size of the compiled form (in arbitrary units, usually +4-byte words) and the label I of the first node that does a +match. + +The last line (split into two lines above) contains optimizer +information. In the example shown, the optimizer found that the match +should contain a substring C at offset 1, plus substring C +at some offset between 3 and infinity. Moreover, when checking for +these substrings (to abandon impossible matches quickly), Perl will check +for the substring C before checking for the substring C. The +optimizer may also use the knowledge that the match starts (at the +C I) with a character class, and the match cannot be +shorter than 7 chars. + +The fields of interest which may appear in the last line are + +=over + +=item C I C I + +=item C I C I + +See above. + +=item C + +Which substring to check first. + +=item C + +The minimal length of the match. + +=item C I + +Type of first matching node. + +=item C + +Don't scan for the found substrings. + +=item C + +Means that the optimizer info is all that the regular +expression contains, and thus one does not need to enter the regex engine at +all. + +=item C + +Set if the pattern contains C<\G>. + +=item C + +Set if the pattern starts with a repeated char (as in C). + +=item C + +Set if the pattern starts with C<.*>. + +=item C + +Set if the pattern contain eval-groups, such as C<(?{ code })> and +C<(??{ code })>. + +=item C + +If the pattern may match only at a handful of places, (with C +being C, C, or C. See the table below. + +=back + +If a substring is known to match at end-of-line only, it may be +followed by C<$>, as in C. + +The optimizer-specific info is used to avoid entering (a slow) regex +engine on strings that will not definitely match. If C flag +is set, a call to the regex engine may be avoided even when the optimizer +found an appropriate place for the match. + +The rest of the output contains the list of I of the compiled +form of the regex. Each line has format + +C< >I: I I (I) + +=head2 Types of nodes + +Here are the possible types, with short descriptions: + + # TYPE arg-description [num-args] [longjump-len] DESCRIPTION + + # Exit points + END no End of program. + SUCCEED no Return from a subroutine, basically. + + # Anchors: + BOL no Match "" at beginning of line. + MBOL no Same, assuming multiline. + SBOL no Same, assuming singleline. + EOS no Match "" at end of string. + EOL no Match "" at end of line. + MEOL no Same, assuming multiline. + SEOL no Same, assuming singleline. + BOUND no Match "" at any word boundary + BOUNDL no Match "" at any word boundary + NBOUND no Match "" at any word non-boundary + NBOUNDL no Match "" at any word non-boundary + GPOS no Matches where last m//g left off. + + # [Special] alternatives + ANY no Match any one character (except newline). + SANY no Match any one character. + ANYOF sv Match character in (or not in) this class. + ALNUM no Match any alphanumeric character + ALNUML no Match any alphanumeric char in locale + NALNUM no Match any non-alphanumeric character + NALNUML no Match any non-alphanumeric char in locale + SPACE no Match any whitespace character + SPACEL no Match any whitespace char in locale + NSPACE no Match any non-whitespace character + NSPACEL no Match any non-whitespace char in locale + DIGIT no Match any numeric character + NDIGIT no Match any non-numeric character + + # BRANCH The set of branches constituting a single choice are hooked + # together with their "next" pointers, since precedence prevents + # anything being concatenated to any individual branch. The + # "next" pointer of the last BRANCH in a choice points to the + # thing following the whole choice. This is also where the + # final "next" pointer of each individual branch points; each + # branch starts with the operand node of a BRANCH node. + # + BRANCH node Match this alternative, or the next... + + # BACK Normal "next" pointers all implicitly point forward; BACK + # exists to make loop structures possible. + # not used + BACK no Match "", "next" ptr points backward. + + # Literals + EXACT sv Match this string (preceded by length). + EXACTF sv Match this string, folded (prec. by length). + EXACTFL sv Match this string, folded in locale (w/len). + + # Do nothing + NOTHING no Match empty string. + # A variant of above which delimits a group, thus stops optimizations + TAIL no Match empty string. Can jump here from outside. + + # STAR,PLUS '?', and complex '*' and '+', are implemented as circular + # BRANCH structures using BACK. Simple cases (one character + # per match) are implemented with STAR and PLUS for speed + # and to minimize recursive plunges. + # + STAR node Match this (simple) thing 0 or more times. + PLUS node Match this (simple) thing 1 or more times. + + CURLY sv 2 Match this simple thing {n,m} times. + CURLYN no 2 Match next-after-this simple thing + # {n,m} times, set parens. + CURLYM no 2 Match this medium-complex thing {n,m} times. + CURLYX sv 2 Match this complex thing {n,m} times. + + # This terminator creates a loop structure for CURLYX + WHILEM no Do curly processing and see if rest matches. + + # OPEN,CLOSE,GROUPP ...are numbered at compile time. + OPEN num 1 Mark this point in input as start of #n. + CLOSE num 1 Analogous to OPEN. + + REF num 1 Match some already matched string + REFF num 1 Match already matched string, folded + REFFL num 1 Match already matched string, folded in loc. + + # grouping assertions + IFMATCH off 1 2 Succeeds if the following matches. + UNLESSM off 1 2 Fails if the following matches. + SUSPEND off 1 1 "Independent" sub-regex. + IFTHEN off 1 1 Switch, should be preceded by switcher . + GROUPP num 1 Whether the group matched. + + # Support for long regex + LONGJMP off 1 1 Jump far away. + BRANCHJ off 1 1 BRANCH with long offset. + + # The heavy worker + EVAL evl 1 Execute some Perl code. + + # Modifiers + MINMOD no Next operator is not greedy. + LOGICAL no Next opcode should set the flag only. + + # This is not used yet + RENUM off 1 1 Group with independently numbered parens. + + # This is not really a node, but an optimized away piece of a "long" node. + # To simplify debugging output, we mark it as if it were a node + OPTIMIZED off Placeholder for dump. + +=head2 Run-time output + +First of all, when doing a match, one may get no run-time output even +if debugging is enabled. This means that the regex engine was never +entered and that all of the job was therefore done by the optimizer. + +If the regex engine was entered, the output may look like this: + + Matching `[bc]d(ef*g)+h[ij]k$' against `abcdefg__gh__' + Setting an EVAL scope, savestack=3 + 2 | 1: ANYOF + 3 | 11: EXACT + 4 | 13: CURLYX {1,32767} + 4 | 26: WHILEM + 0 out of 1..32767 cc=effff31c + 4 | 15: OPEN1 + 4 | 17: EXACT + 5 | 19: STAR + EXACT can match 1 times out of 32767... + Setting an EVAL scope, savestack=3 + 6 | 22: EXACT + 7 <__gh__> | 24: CLOSE1 + 7 <__gh__> | 26: WHILEM + 1 out of 1..32767 cc=effff31c + Setting an EVAL scope, savestack=12 + 7 <__gh__> | 15: OPEN1 + 7 <__gh__> | 17: EXACT + restoring \1 to 4(4)..7 + failed, try continuation... + 7 <__gh__> | 27: NOTHING + 7 <__gh__> | 28: EXACT + failed... + failed... + +The most significant information in the output is about the particular I +of the compiled regex that is currently being tested against the target string. +The format of these lines is + +C< >I > > |I: I + +The I info is indented with respect to the backtracking level. +Other incidental information appears interspersed within. + +=head1 Debugging Perl memory usage + +Perl is a profligate wastrel when it comes to memory use. There +is a saying that to estimate memory usage of Perl, assume a reasonable +algorithm for memory allocation, multiply that estimate by 10, and +while you still may miss the mark, at least you won't be quite so +astonished. This is not absolutely true, but may prvide a good +grasp of what happens. + +Assume that an integer cannot take less than 20 bytes of memory, a +float cannot take less than 24 bytes, a string cannot take less +than 32 bytes (all these examples assume 32-bit architectures, the +result are quite a bit worse on 64-bit architectures). If a variable +is accessed in two of three different ways (which require an integer, +a float, or a string), the memory footprint may increase yet another +20 bytes. A sloppy malloc(3) implementation can make inflate these +numbers dramatically. + +On the opposite end of the scale, a declaration like + + sub foo; + +may take up to 500 bytes of memory, depending on which release of Perl +you're running. + +Anecdotal estimates of source-to-compiled code bloat suggest an +eightfold increase. This means that the compiled form of reasonable +(normally commented, properly indented etc.) code will take +about eight times more space in memory than the code took +on disk. + +There are two Perl-specific ways to analyze memory usage: +$ENV{PERL_DEBUG_MSTATS} and B<-DL> command-line switch. The first +is available only if Perl is compiled with Perl's malloc(); the +second only if Perl was built with C<-DDEBUGGING>. See the +instructions for how to do this in the F podpage at +the top level of the Perl source tree. + +=head2 Using C<$ENV{PERL_DEBUG_MSTATS}> + +If your perl is using Perl's malloc() and was compiled with the +necessary switches (this is the default), then it will print memory +usage statistics after compiling your code hwen C<< $ENV{PERL_DEBUG_MSTATS} +> 1 >>, and before termination of the program when C<< +$ENV{PERL_DEBUG_MSTATS} >= 1 >>. The report format is similar to +the following example: + + $ PERL_DEBUG_MSTATS=2 perl -e "require Carp" + Memory allocation statistics after compilation: (buckets 4(4)..8188(8192) + 14216 free: 130 117 28 7 9 0 2 2 1 0 0 + 437 61 36 0 5 + 60924 used: 125 137 161 55 7 8 6 16 2 0 1 + 74 109 304 84 20 + Total sbrk(): 77824/21:119. Odd ends: pad+heads+chain+tail: 0+636+0+2048. + Memory allocation statistics after execution: (buckets 4(4)..8188(8192) + 30888 free: 245 78 85 13 6 2 1 3 2 0 1 + 315 162 39 42 11 + 175816 used: 265 176 1112 111 26 22 11 27 2 1 1 + 196 178 1066 798 39 + Total sbrk(): 215040/47:145. Odd ends: pad+heads+chain+tail: 0+2192+0+6144. + +It is possible to ask for such a statistic at arbitrary points in +your execution using the mstats() function out of the standard +Devel::Peek module. + +Here is some explanation of that format: + +=over + +=item C + +Perl's malloc() uses bucketed allocations. Every request is rounded +up to the closest bucket size available, and a bucket is taken from +the pool of buckets of that size. + +The line above describes the limits of buckets currently in use. +Each bucket has two sizes: memory footprint and the maximal size +of user data that can fit into this bucket. Suppose in the above +example that the smallest bucket were size 4. The biggest bucket +would have usable size 8188, and the memory footprint would be 8192. + +In a Perl built for debugging, some buckets may have negative usable +size. This means that these buckets cannot (and will not) be used. +For larger buckets, the memory footprint may be one page greater +than a power of 2. If so, case the corresponding power of two is +printed in the C field above. + +=item Free/Used + +The 1 or 2 rows of numbers following that correspond to the number +of buckets of each size between C and C. In +the first row, the sizes (memory footprints) of buckets are powers +of two--or possibly one page greater. In the second row, if present, +the memory footprints of the buckets are between the memory footprints +of two buckets "above". + +For example, suppose under the pervious example, the memory footprints +were + + free: 8 16 32 64 128 256 512 1024 2048 4096 8192 + 4 12 24 48 80 + +With non-C perl, the buckets starting from C<128> have +a 4-byte overhead, and thus a 8192-long bucket may take up to +8188-byte allocations. + +=item C + +The first two fields give the total amount of memory perl sbrk(2)ed +(ess-broken? :-) and number of sbrk(2)s used. The third number is +what perl thinks about continuity of returned chunks. So long as +this number is positive, malloc() will assume that it is probable +that sbrk(2) will provide continuous memory. + +Memory allocated by external libraries is not counted. + +=item C + +The amount of sbrk(2)ed memory needed to keep buckets aligned. + +=item C + +Although memory overhead of bigger buckets is kept inside the bucket, for +smaller buckets, it is kept in separate areas. This field gives the +total size of these areas. + +=item C + +malloc() may want to subdivide a bigger bucket into smaller buckets. +If only a part of the deceased bucket is left unsubdivided, the rest +is kept as an element of a linked list. This field gives the total +size of these chunks. + +=item C + +To minimize the number of sbrk(2)s, malloc() asks for more memory. This +field gives the size of the yet unused part, which is sbrk(2)ed, but +never touched. + +=back + +=head2 Example of using B<-DL> switch + +Below we show how to analyse memory usage by + + do 'lib/auto/POSIX/autosplit.ix'; + +The file in question contains a header and 146 lines similar to + + sub getcwd; + +B: The discussion below supposes 32-bit architecture. In +newer releases of Perl, memory usage of the constructs discussed +here is greatly improved, but the story discussed below is a real-life +story. This story is mercilessly terse, and assumes rather more than cursory +knowledge of Perl internals. Type space to continue, `q' to quit. +(Actually, you just want to skip to the next section.) + +Here is the itemized list of Perl allocations performed during parsing +of this file: + + !!! "after" at test.pl line 3. + Id subtot 4 8 12 16 20 24 28 32 36 40 48 56 64 72 80 80+ + 0 02 13752 . . . . 294 . . . . . . . . . . 4 + 0 54 5545 . . 8 124 16 . . . 1 1 . . . . . 3 + 5 05 32 . . . . . . . 1 . . . . . . . . + 6 02 7152 . . . . . . . . . . 149 . . . . . + 7 02 3600 . . . . . 150 . . . . . . . . . . + 7 03 64 . -1 . 1 . . 2 . . . . . . . . . + 7 04 7056 . . . . . . . . . . . . . . . 7 + 7 17 38404 . . . . . . . 1 . . 442 149 . . 147 . + 9 03 2078 17 249 32 . . . . 2 . . . . . . . . + + +To see this list, insert two C statements around the call: + + warn('!'); + do 'lib/auto/POSIX/autosplit.ix'; + warn('!!! "after"'); + +and run it with PErl's B<-DL> option. The first warn() will print +memory allocation info before parsing the file and will memorize +the statistics at this point (we ignore what it prints). The second +warn() prints increments with respect to these memorized data. This +is the printout shown above. + +Different Is on the left correspond to different subsystems of +the perl interpreter. They are just the first argument given to +the perl memory allocation API named New(). To find what C<9 03> +means, just B the perl source for C<903>. You'll find it in +F, function savepvn(). (I know, you wonder why we told you +to B and then gave away the answer. That's because grepping +the source is good for the soul.) This function is used to store +a copy of an existing chunk of memory. Using a C debugger, one can +see that the function was called either directly from gv_init() or +via sv_magic(), and that gv_init() is called from gv_fetchpv()--which +was itself called from newSUB(). Please stop to catch your breath now. + +B: To reach this point in the debugger and skip the calls to +savepvn() during the compilation of the main program, you should +set a C breakpoint +in Perl_warn(), continue until this point is reached, and I set +a C breakpoint in Perl_savepvn(). Note that you may need to skip a +handful of Perl_savepvn() calls that do not correspond to mass production +of CVs (there are more C<903> allocations than 146 similar lines of +F). Note also that C prefixes are +added by macroization code in perl header files to avoid conflicts +with external libraries. + +Anyway, we see that C<903> ids correspond to creation of globs, twice +per glob - for glob name, and glob stringification magic. + +Here are explanations for other Is above: + +=over + +=item C<717> + +CReates bigger C structures. In the case above, it +creates 3 Cs per subroutine, one for a list of lexical variable +names, one for a scratchpad (which contains lexical variables and +C), and one for the array of scratchpads needed for +recursion. + +It also creates a C and a C per subroutine, all called from +start_subparse(). + +=item C<002> + +Creates a C array corresponding to the C of scratchpads and the +scratchpad itself. The first fake entry of this scratchpad is +created though the subroutine itself is not defined yet. + +It also creates C arrays to keep data for the stash. This is one HV, +but it grows; thus, there are 4 big allocations: the big chunks are not +freed, but are kept as additional arenas for C allocations. + +=item C<054> + +Creates a C for the name of the glob for the subroutine. This +name is a key in a I. + +Big allocations with this I correspond to allocations of new +arenas to keep C. + +=item C<602> + +Creates a C for the glob for the subroutine. + +=item C<702> + +Creates the C for the glob for the subroutine. + +=item C<704> + +Creates I which keep SVs. + +=back + +=head2 B<-DL> details + +If Perl is run with B<-DL> option, then warn()s that start with `!' +behave specially. They print a list of I of memory +allocations, and statistics of allocations of different sizes for +these categories. + +If warn() string starts with + +=over + +=item C + +print changed categories only, print the differences in counts of allocations. + +=item C + +print grown categories only; print the absolute values of counts, and totals. + +=item C + +print nonempty categories, print the absolute values of counts and totals. + +=back + +=head2 Limitations of B<-DL> statistics + +If an extension or external library does not use the Perl API to +allocate memory, such allocations are not counted. + +=head1 SEE ALSO + +L, +L, +L +L, +and +L. diff --git a/pod/perldebug.pod b/pod/perldebug.pod index fe24184..5b7a2bd 100644 --- a/pod/perldebug.pod +++ b/pod/perldebug.pod @@ -8,15 +8,6 @@ First of all, have you tried using the B<-w> switch? =head1 The Perl Debugger -"As soon as we started programming, we found to our -surprise that it wasn't as easy to get programs right -as we had thought. Debugging had to be discovered. -I can remember the exact instant when I realized that -a large part of my life from then on was going to be -spent in finding mistakes in my own programs." - -I< --Maurice Wilkes, 1949> - If you invoke Perl with the B<-d> switch, your script runs under the Perl source debugger. This works like an interactive Perl environment, prompting for debugger commands that let you examine @@ -25,14 +16,14 @@ variables, etc. This is so convenient that you often fire up the debugger all by itself just to test out Perl constructs interactively to see what they do. For example: - perl -d -e 42 + $ perl -d -e 42 -In Perl, the debugger is not a separate program as it usually is in the +In Perl, the debugger is not a separate program the way it usually is in the typical compiled environment. Instead, the B<-d> flag tells the compiler to insert source information into the parse trees it's about to hand off to the interpreter. That means your code must first compile correctly for the debugger to work on it. Then when the interpreter starts up, it -preloads a Perl library file containing the debugger itself. +preloads a special Perl library file containing the debugger. The program will halt I the first run-time executable statement (but see below regarding compile-time statements) and ask you @@ -41,12 +32,15 @@ the debugger halts and shows you a line of code, it always displays the line it's I to execute, rather than the one it has just executed. Any command not recognized by the debugger is directly executed -(C'd) as Perl code in the current package. (The debugger uses the -DB package for its own state information.) +(C'd) as Perl code in the current package. (The debugger +uses the DB package for keeping its own state information.) -Leading white space before a command would cause the debugger to think -it's I a debugger command but for Perl, so be careful not to do -that. +For any text entered at the debugger prompt, leading and trailing whitespace +is first stripped before further processing. If a debugger command +coincides with some function in your own program, merely precede the +function with something that doesn't look like a debugger command, such +as a leading C<;> or perhaps a C<+>, or by wrapping it with parentheses +or braces. =head2 Debugger Commands @@ -64,8 +58,8 @@ argument of C produces a more compact help listing, designed to fit together on one screen. If the output of the C command (or any command, for that matter) scrolls -past your screen, either precede the command with a leading pipe symbol so -it's run through your pager, as in +past your screen, precede the command with a leading pipe symbol so +that it's run through your pager, as in DB> |h @@ -84,26 +78,25 @@ where STDOUT may be redirected to. Evaluates its expression in list context and dumps out the result in a pretty-printed fashion. Nested data structures are printed out -recursively, unlike the C function. +recursively, unlike the real C function in Perl. +See L if you'd like to do this yourself. -The details of printout are governed by multiple Cptions. +The output format is governed by multiple options described under +L<"Options">. =item V [pkg [vars]] -Display all (or some) variables in package (defaulting to the C
-package) using a data pretty-printer (hashes show their keys and values so -you see what's what, control characters are made printable, etc.). Make -sure you don't put the type specifier (like C<$>) there, just the symbol -names, like this: +Display all (or some) variables in package (defaulting to C
) +using a data pretty-printer (hashes show their keys and values so +you see what's what, control characters are made printable, etc.). +Make sure you don't put the type specifier (like C<$>) there, just +the symbol names, like this: V DB filename line -Use C<~pattern> and C for positive and negative regexps. - -Nested data structures are printed out in a legible fashion, unlike -the C function. +Use C<~pattern> and C for positive and negative regexes. -The details of printout are governed by multiple Cptions. +This is similar to calling the C command on each applicable var. =item X [vars] @@ -115,21 +108,21 @@ Produce a stack backtrace. See below for details on its output. =item s [expr] -Single step. Executes until it reaches the beginning of another +Single step. Executes until the beginning of another statement, descending into subroutine calls. If an expression is supplied that includes function calls, it too will be single-stepped. =item n [expr] -Next. Executes over subroutine calls, until it reaches the beginning +Next. Executes over subroutine calls, until the beginning of the next statement. If an expression is supplied that includes function calls, those functions will be executed with stops before each statement. =item r -Continue until return from the current subroutine. Dump the return -value, if the PrintRet option is set (default). +Continue until the return from the current subroutine. +Dump the return value if the C option is set (default). =item @@ -159,7 +152,7 @@ List a single line. =item l subname List first window of lines from subroutine. I may -be a variable which contains a code reference. +be a variable that contains a code reference. =item - @@ -171,24 +164,24 @@ List window (a few lines) around the current line. =item . -Return debugger pointer to the last-executed line and -print it out. +Return the internal debugger pointer to the line last +executed, and print out that line. =item f filename -Switch to viewing a different file or eval statement. If C -is not a full filename as found in values of %INC, it is considered as -a regexp. +Switch to viewing a different file or C statement. If I +is not a full pathname found in the values of %INC, it is considered +a regex. Ced strings (when accessible) are considered to be filenames: C and C access the body of the 7th Ced string -(in the order of execution). The bodies of currently executed C -and of Ced strings which define subroutines are saved, thus are -accessible by this mechanism. +(in the order of execution). The bodies of the currently executed C +and of Ced strings that define subroutines are saved and thus +accessible. =item /pattern/ -Search forwards for pattern; final / is optional. +Search forwards for pattern (a Perl regex); final / is optional. =item ?pattern? @@ -198,58 +191,27 @@ Search backwards for pattern; final ? is optional. List all breakpoints and actions. -=item S [[!]pattern] +=item S [[!]regex] -List subroutine names [not] matching pattern. +List subroutine names [not] matching the regex. =item t -Toggle trace mode (see also C Cption). +Toggle trace mode (see also the C option). =item t expr -Trace through execution of expr. For example: - - $ perl -de 42 - Stack dump during die enabled outside of evals. - - Loading DB routines from perl5db.pl patch level 0.94 - Emacs support available. - - Enter h or `h h' for help. - - main::(-e:1): 0 - DB<1> sub foo { 14 } - - DB<2> sub bar { 3 } - - DB<3> t print foo() * bar() - main::((eval 172):3): print foo() + bar(); - main::foo((eval 168):2): - main::bar((eval 170):2): - 42 - -or, with the Cption C set, - - DB<4> O f=2 - frame = '2' - DB<5> t print foo() * bar() - 3: foo() * bar() - entering main::foo - 2: sub foo { 14 }; - exited main::foo - entering main::bar - 2: sub bar { 3 }; - exited main::bar - 42 +Trace through execution of C. +See L for examples. =item b [line] [condition] -Set a breakpoint. If line is omitted, sets a breakpoint on the line -that is about to be executed. If a condition is specified, it's -evaluated each time the statement is reached and a breakpoint is taken -only if the condition is true. Breakpoints may be set on only lines -that begin an executable statement. Conditions don't use B: +Set a breakpoint before the given line. If I is omitted, set a +breakpoint on the line about to be executed. If a condition +is specified, it's evaluated each time the statement is reached: a +breakpoint is taken only if the condition is true. Breakpoints may +only be set on lines that begin an executable statement. Conditions +don't use B: b 237 $x > 30 b 237 ++$count237 < 11 @@ -257,28 +219,28 @@ that begin an executable statement. Conditions don't use B: =item b subname [condition] -Set a breakpoint at the first line of the named subroutine. I may -be a variable which contains a code reference (in this case I +Set a breakpoint before the first line of the named subroutine. I may +be a variable containing a code reference (in this case I is not supported). =item b postpone subname [condition] -Set breakpoint at first line of subroutine after it is compiled. +Set a breakpoint at first line of subroutine after it is compiled. =item b load filename -Set breakpoint at the first executed line of the file. Filename should -be a full name as found in values of %INC. +Set a breakpoint before the first executed line of the I, +which should be a full pathname found amongst the %INC values. =item b compile subname -Sets breakpoint at the first statement executed after the subroutine -is compiled. +Sets a breakpoint before the first statement executed after the specified +subroutine is compiled. =item d [line] -Delete a breakpoint at the specified line. If line is omitted, deletes -the breakpoint on the line that is about to be executed. +Delete a breakpoint from the specified I. If I is omitted, deletes +the breakpoint from the line about to be executed. =item D @@ -286,8 +248,8 @@ Delete all installed breakpoints. =item a [line] command -Set an action to be done before the line is executed. If line is -omitted, sets an action on the line that is about to be executed. +Set an action to be done before the line is executed. If I is +omitted, set an action on the line about to be executed. The sequence of steps taken by the debugger is 1. check for a breakpoint at this line @@ -303,38 +265,222 @@ For example, this will print out $foo every time line =item a [line] -Delete an action at the specified line. If line is omitted, deletes +Delete an action from the specified line. If I is omitted, delete the action on the line that is about to be executed. =item A Delete all installed actions. -=item W [expr] +=item W expr -Add a global watch-expression. +Add a global watch-expression. We hope you know what one of these +is, because they're supposed to be obvious. B: It is far +too easy to destroy your watch expressions by accidentally omitting +the I. =item W Delete all watch-expressions. -=item O [opt[=val]] [opt"val"] [opt?]... +=item O booloption ... + +Set each listed Boolean option to the value C<1>. + +=item O anyoption? ... + +Print out the value of one or more options. + +=item O option=value ... + +Set the value of one or more options. If the value has internal +whitespace, it should be quoted. For example, you could set C to call B with those specific options. +You may use either single or double quotes, but if you do, you must +escape any embedded instances of same sort of quote you began with, +as well as any escaping any escapes that immediately precede that +quote but which are not meant to escape the quote itself. In other +words, you follow single-quoting rules irrespective of the quote; +eg: C or C. + +For historical reasons, the C<=value> is optional, but defaults to +1 only where it is safe to do so--that is, mostly for Boolean +options. It is always better to assign a specific value using C<=>. +The C