default warnLevel and dieLevel to 0 in debugger (from Tom

Christiansen); make dumpvar.pl safe against non-glob entries
in stashes

p4raw-id: //depot/perl@5818

4 files changed, 35 insertions, 19 deletions

diff --git a/lib/Dumpvalue.pm b/lib/Dumpvalue.pm
index 94b6aa6e78..5d3a9dafc2 100644
--- a/lib/Dumpvalue.pm
+++ b/lib/Dumpvalue.pm
@@ -404,7 +404,8 @@ sub dumpvars {
     next if @vars && !grep( matchvar($key, $_), @vars );
     if ($self->{usageOnly}) {
       $self->globUsage(\$val, $key)
-	unless $package eq 'Dumpvalue' and $key eq 'stab';
+	if ($package ne 'Dumpvalue' or $key ne 'stab')
+	   and ref(\$val) eq 'GLOB';
     } else {
       $self->dumpglob($package, 0,$key, $val);
     }
diff --git a/lib/dumpvar.pl b/lib/dumpvar.pl
index c72781801b..4a3041a02b 100644
--- a/lib/dumpvar.pl
+++ b/lib/dumpvar.pl
@@ -361,7 +361,9 @@ sub main::dumpvar {
       return if $DB::signal;
       next if @vars && !grep( matchvar($key, $_), @vars );
       if ($usageOnly) {
-	globUsage(\$val, $key) unless $package eq 'dumpvar' and $key eq 'stab';
+	globUsage(\$val, $key)
+	  if ($package ne 'dumpvar' or $key ne 'stab')
+	     and ref(\$val) eq 'GLOB';
       } else {
 	dumpglob(0,$key, $val);
       }
diff --git a/lib/perl5db.pl b/lib/perl5db.pl
index 23fcb1cae4..132e08e0bd 100644
--- a/lib/perl5db.pl
+++ b/lib/perl5db.pl
@@ -273,13 +273,13 @@ $inhibit_exit = $option{PrintRet} = 1;
 		 );
 
 # These guys may be defined in $ENV{PERL5DB} :
-$rl = 1 unless defined $rl;
-$warnLevel = 1 unless defined $warnLevel;
-$dieLevel = 1 unless defined $dieLevel;
-$signalLevel = 1 unless defined $signalLevel;
-$pre = [] unless defined $pre;
-$post = [] unless defined $post;
-$pretype = [] unless defined $pretype;
+$rl		= 1	unless defined $rl;
+$warnLevel	= 0	unless defined $warnLevel;
+$dieLevel	= 0	unless defined $dieLevel;
+$signalLevel	= 1	unless defined $signalLevel;
+$pre		= []	unless defined $pre;
+$post		= []	unless defined $post;
+$pretype	= []	unless defined $pretype;
 
 warnLevel($warnLevel);
 dieLevel($dieLevel);
diff --git a/pod/perldebug.pod b/pod/perldebug.pod
index ead5414ccf..1750f1a5c0 100644
--- a/pod/perldebug.pod
+++ b/pod/perldebug.pod
@@ -488,16 +488,23 @@ Run Tk while prompting (with ReadLine).
 
 =item C<signalLevel>, C<warnLevel>, C<dieLevel>
 
-Level of verbosity.  By default, the debugger prints backtraces
-upon receiving any kind of warning (this is often annoying) and
-fatal exceptions (this is often valuable).  It will attempt to print
-a message when uncaught INT, BUS, or SEGV signals arrive.
-
-To disable this behaviour, set these values to 0.  If C<dieLevel>
-is 2, the debugger usurps your own exception handler and prints out
-a trace of these, replacing your exceptions with its own.  This may
-be useful for some tracing purposes, but tends to hopelessly destroy
-any program that takes its exception handling seriously.
+Level of verbosity.  By default, the debugger leaves your exceptions
+and warnings alone, because altering them can break correctly running
+programs.  It will attempt to print a message when uncaught INT, BUS, or
+SEGV signals arrive.  (But see the mention of signals in L<BUGS> below.)
+
+To disable this default safe mode, set these values to something higher
+than 0.  At a level of 1, you get backtraces upon receiving any kind
+of warning (this is often annoying) or exception (this is
+often valuable).  Unfortunately, the debugger cannot discern fatal
+exceptions from non-fatal ones.  If C<dieLevel> is even 1, then your
+non-fatal exceptions are also traced and unceremoniously altered if they
+came from C<eval'd> strings or from any kind of C<eval> within modules
+you're attempting to load.  If C<dieLevel> is 2, the debugger doesn't
+care where they came from:  It usurps your exception handler and prints
+out a trace, then modifies all exceptions with its own embellishments.
+This may perhaps be useful for some tracing purposes, but tends to hopelessly
+destroy any program that takes its exception handling seriously.
 
 =item C<AutoTrace>
 
@@ -929,3 +936,9 @@ that were not compiled by Perl, such as those from C or C++ extensions.
 
 If you alter your @_ arguments in a subroutine (such as with B<shift>
 or B<pop>, the stack backtrace will not show the original values.
+
+If you're in a slow syscall (like C<wait>ing, C<accept>ing, or C<read>ing
+from your keyboard or a socket) and haven't set up your own C<$SIG{INT}>
+handler, then you won't be able to CTRL-C your way back to the debugger,
+because the debugger's own C<$SIG{INT}> handler doesn't understand that
+it needs to raise an exception to longjmp(3) out of slow syscalls.