#!/usr/bin/perl
use strict;
use File::Find;
use Fcntl ':mode';
use Cwd;

my $VER = shift;
my $SRC = shift;
my $DESTDIR = shift;
my $cwd;

$VER = "2.6.14"			if !defined($VER);
$SRC   = "../linux"		if !defined($SRC);
$DESTDIR = "/tmp/linux"		if !defined($DESTDIR);

my ($VERSION,$CODE) = &kernel_version;
my $DEBUG = 0;


#################################################################
# helpers

sub kernel_version() {
	my ($ver,$code);

	$code = 0;
	$ver = $VER;

	$ver =~ m/^(\d)\.(\d)\.(\d)/;
	my $v1 = $1;
	my $v2 = $2;
	my $v3 = $3;
	foreach my $name ($v1, $v2, $v3) {
		$code = $code * 256 + $1;
	}

	return ($ver,$code);
}


#################################################################
# filter out version-specific code

sub filter_source ($$) {
	my ($in,$out) = @_;
	my ($line,$if,$state,$mmkernel);

	open IN,  "<$in";
	open OUT, ">$out";

	while ($line = <IN>) {
		die "nested" if defined($state) && $line =~ /^#if/;
		if ($line =~ m/^#include <linux\/version.h>/ &&
		    $in   =~ m/.*\.c/) {
			next;
		}
		if ($line =~ m/^#include \"compat.h\"/) {
			next;
		}
		if ($line =~ m/[\$]Id:/) {
			next;
		}
		if ($line =~ /^#ifdef MM_KERNEL/) {
			chomp($line);
			$state = "if";
			$if = $mmkernel;
			print OUT "/* BP #if $if ($line) */\n" if $DEBUG;
			next;
		}
		if ($line =~ /^#if 0/) {
			chomp($line);
			$state = "if";
			$if = 0;
			print OUT "/* BP #if $if ($line) */\n" if $DEBUG;
			next;
		}
		if ($line =~ /^#if 1 .*KEEP.*/) {
			print OUT "#if 1\n";
			next;
		}
		if ($line =~ /^#if 1/) {
			chomp($line);
			$state = "if";
			$if = 1;
			print OUT "/* BP #if $if ($line) */\n" if $DEBUG;
			next;
		}
		if ($line =~ /^#if.*BTTV_VERSION_CODE/) {
			chomp($line);
			$state = "if";
			$line =~ s@^#if\s*@@;
			$line =~ s@BTTV_VERSION_CODE@\$CODE@;
			$line =~ s@KERNEL_VERSION\((\d+),\s*(\d+),\s*(\d+)\)@
					sprintf("%d",$1*65536 + $2*256 + $3) @e;
			$if = eval $line;
			print OUT "/* BP #if $if ($line) */\n" if $DEBUG;
			next;
		}
		if ($line =~ /^#if.*LINUX_VERSION_CODE/) {
			chomp($line);
			$line =~ s@^#if\s*@@;
			$line =~ s@LINUX_VERSION_CODE@\$CODE@;
			$line =~ s@KERNEL_VERSION\((\d+),\s*(\d+),\s*(\d+)\)@
					sprintf("%d",$1*65536 + $2*256 + $3) @e;
			$if = eval $line;
			$state = "if";
			print OUT "/* BP #if $if ($line) */\n" if $DEBUG;
			next;
		}
		if (defined($state) && $line =~ /^#else/) {
			$state = "else";
			print OUT "/* BP #else */\n" if $DEBUG;
			next;
		}
		if (defined($state) && $line =~ /^#endif/) {
			undef $state;
			print OUT "/* BP #endif */\n" if $DEBUG;
			next;
		}
		if (!defined($state)		||
		    $state eq "if"   && $if	||
		    $state eq "else" && !$if) {
			print OUT $line;
		} else {
			chomp($line);
			print OUT "/* BP DEL $line */\n" if $DEBUG;
		}
	}
	close IN;
	close OUT;
}

#################################################################

sub parse_dir {
	my $file = $File::Find::name;
	my $srcdir=$SRC;

	if ($file =~ /CVS/) {
		return;
	}

	if ($file =~ /\~$/) {
		return;
	}

	my $mode = (lstat("$cwd/$file"))[2];

#	printf "Permissions of %s/%s are %04o (dir=%s\n", $cwd,$file, $mode, cwd;

	if ($mode & S_IFDIR) {
		return;
	}

	$srcdir =~ s/(.)/\[$1\]/g;
	my $f2 = $file;

	$f2 =~ s,^$srcdir,$cwd/$DESTDIR/,;
	print STDERR "from $file to $f2\n";

	my $tmp = "/tmp/src.$$";
	filter_source("$cwd/$file","$tmp");

	my $dir = $f2;
	$dir =~ s,(.*)[/][^/]*$,$1,;

	print("mkdir -p $dir\n");
	system("mkdir -p $dir\n");
	system("cp $tmp $f2");
	unlink $tmp;
}


# main

my $patchtmploc = "/tmp/temp.patch";

printf STDERR <<EOF,$VER,$CODE;
kernel is %s (0x%x)
EOF

print STDERR "finding files at $SRC\n";

$cwd=cwd;

find(\&parse_dir, $SRC);