Are all signals unsafe? Or just the alarm and interrupt signals? What about warn?

I wrote a handler for warnings to give me some more info when things break. But if the warning handler makes things break as well, then obviously I don't want to use it. Is this code bad?

Update: This is under ActiveState Perl 5.6.1, on WinXP 

$SIG{__WARN__} = \&mywarn;
# ...
sub mywarn {
    my $warning = shift;
    my $i = 0;
    open (WRNLOG, ">>Warnings.log") || warn "Can't open warnings log f
+ile: $!";
    # If open failed, output will be discarded
    print STDOUT "WARNING: $warning";
    print WRNLOG "WARNING: $warning";
    print STDOUT "         Stack Trace:\n";
    print WRNLOG "         Stack Trace:\n";
    while (caller($i)) {
        my (undef, $filename, $line, $sub) = caller($i);
        print STDOUT "         $filename ($line) --- $sub\n";
        print WRNLOG "         $filename ($line) --- $sub\n";
        $i++;
    }
    print STDOUT "\n";
    print WRNLOG "\n";
}

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In reply to Which signals are unsafe? by Sprad

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