#!/usr/bin/perl

$version = "1.0";
$timeout = 5;
@pkgs    = ( "xorg-x11-server", "xorg-x11-driver-video", "xorg-x11-driver-input",
             "libpixman-1-0", "libpciaccess0" );
$xtracmds= "/etc/X11/xorg-backtrace-cmds";


$pid=$ARGV[0];
if ($pid == 0) {
    print "Usage: $0 <pid>\n";
    exit 1;
}


if (! -e "/usr/bin/gdb") {
    print "Install gdb to get reasonable backtraces\n";
    exit 2;
}

$SIG{ALRM} = sub { die "timeout starting gdb" };
alarm $timeout;

open STDERR, ">&STDOUT";

use FileHandle;
use IPC::Open2;
$gdb = open2 (*R, *W, "/usr/bin/gdb -n -p $pid");

$SIG{ALRM} = sub { kill QUIT, $gdb; sleep 1; kill KILL, $gdb; die "timeout using gdb" };
alarm $timeout;


print "\n==================== GDB Backtrace ============\n\n";
print "Done by $0 V$version\n\n";

$needpkgs=0;
for $p (@pkgs) {
    next if system ("rpm", "-q", "--quiet", "$p-debuginfo") == 0 &&
	    system ("rpm", "-q", "--quiet", "$p-debugsource") == 0;
    print "Install following debug packages to improve backtrace:\n" unless $needpkgs;
    $needpkgs++;
    print "\t$p-debug*\n";
}
print "\n" if $needpkgs;

print W "set prompt\necho \\n===info\\n\n";
#print W "info files\necho ===files\\n\n";
print W "thread apply all bt full\necho ===btend\\n\n";

$_=<R>;			# GNU gdb version
print;

while (<R>) {
    last if /^===info/;
    print if /^This GDB was configured as/;
}

#print "\n==================== Files ====================\n\n";
#while (<R>) {
#    last if /^===files/;
#    print;
#}


print "\n==================== Backtrace ================\n";
$fno = "";
$fls = 0;
$o   = "";
$use = 0;
while (<R>) {
    last if /^===btend/;
    if (/^#(\d+)\s/) {
	$fno = $1;
	$o .= "\n";
	$o .= "===l".($fno-1)."\n" if $use;
	$o .= "\n";
        $fls = $fno+1 if /\bxorg_backtrace \(/ || /\bOsSigHandler \(/;
	$use = 1;
    }
    $line{$fno} = $1 if $line{$fno} == 0 && /:(\d+)\s*$/;
    $o .= $_;
    $use = 0 if /^No symbol table info available/;
}
$o .="\n===l$fno";

for $i ($fls..$fno) {
    print W "frame $i\necho ===fs$i\\n\nlist\necho ===fe$i\\n\n";
    while (<R>) {
	last if /^===fs$i\b/;
    }
    $r = "";
    while (<R>) {
	last if /^===fe$i\b/;
	$r .= $_;
    }
    if ($line{$i} > 0) {
	$r =~ s/^$line{$i}\b/$line{$i} */m;
    }
    $o =~ s/^===l$i$/$r/m;
}

if ($fls > 0) {
    for $i (0..$fls-1) {
	$o =~ s/^(#$i\s.*?)\n.*?\n#/$1\n\n#/ms;
    }
}
$o =~ s/^===l.*$//mg;

print "$o";

if (-e $xtracmds) {
    print W "source -v $xtracmds\necho ===cmds\\n\n";
    print "\n==================== Extra Commands ===========\n\n";
    while (<R>) {
	last if /^===cmds/;
	print unless /^\+echo ===cmds/;
    }
}

print "\n==================== Backtrace End ============\n\n";
close R;
close W;

exit 0;