#!/usr/bin/perl

=pod

=head1 Name

dpkg-cross - manage libraries for cross compiling

=cut

=head1 Copyright and Licence

 Copyright (C) 1997-2000  Roman Hodek <roman@hodek.net>
 Copyright (C) 2000-2002  Colin Watson <cjwatson@debian.org>
 Copyright (C) 2002-2004  David Schleef <ds@schleef.org>
 Copyright (C) 2004  Nikita Youshchenko <yoush@cs.msu.su>
 Copyright (C) 2004  Raphael Bossek <bossekr@debian.org>
 Copyright (c) 2007-2008  Neil Williams <codehelp@debian.org>

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2 of the License, or
 (at your option) any later version.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

=cut

=head1 SYNOPSIS

 dpkg-cross [ -v | --verbose ] [ -q | --quiet ] [ -A | --convert-anyway ]
 [ -X | --exclude PACKAGE ] [ -k | --keep-temp ] { -i | --install 
 | -b | --build | -r | --remove | --purge | -s | --status | -l | --list 
 | -L | --list-files | -u | --update | -Q | --query } 
 { -a | --arch architecture} package [package ... ]

=cut

=head1 DESCRIPTION

dpkg-cross is a tool to install and manage libraries and header files
for cross compiling. dpkg-cross converts native Debian packages for the
target architecture to cross compiling support packages that can be
installed on any architecture, but in different paths to avoid
conflicts. It then calls dpkg to install the converted package. The
conversion step alone can be done with the --build option. Other
options are wrappers around corresponding dpkg functionality.

dpkg-cross is intended to make it easier for you to keep your cross
compiling libraries up-to-date, as it works directly on Debian
packages. It saves you copying the libs and headers from a machine
with your target  architecture, or extracting them via
dpkg-deb --fsys-tarfile. 

dpkg-cross also collects and install the .shlibs files in -dev packages,
which are needed by dpkg-shlibdeps.

dpkg-cross works in the directories defined in 
/etc/dpkg-cross/cross-compile; see cross-compile(5) for more
information.

=cut

=head1 CMAKE

CMake cross-building support is experimental!

CMake requires a little support from dpkg-cross to cross-build. The
included cmake support file is an example for Linux kernels.  Use:

 rm CMakeCache.txt
 cmake -DCMAKE_TOOLCHAIN_FILE=/etc/dpkg-cross/cmake/CMakeCross.txt

The  main changes involve setting PKG_CONFIG_LIBDIR within CMake an
setting the include directories to locate the cross libraries installed
by dpkg-cross e.g.

 #Make pkg-config look in the right place
 SET(ENV{PKG_CONFIG_LIBDIR} ${CMAKE_FIND_ROOT_PATH}/lib/pkgconfig/)
 ELSE (CMAKE_CROSSCOMPILING)

Packages using cmake may need some tweaks to debian/rules, e.g.

 ifneq ($(DEB_HOST_GNU_TYPE),$(DEB_BUILD_GNU_TYPE))
 export CC=$(DEB_HOST_GNU_TYPE)-gcc
 export CXX=$(DEB_HOST_GNU_TYPE)-g++
 export CMAKE_TOOLCHAIN_FILE=/etc/dpkg-cross/cmake/CMakeCross.txt
 else
 export CC=gcc
 export CXX=g++
 endif

=cut

=head1 OPTIONS

dpkg-cross follows the usual GNU command line syntax, with long options
starting with two dashes ('-').

 -h|--help

Show summary of options.

 -v|--verbose

Be more verbose.

 -q|--quiet

Be more quiet.

 -a|--arch architecture

Install for architecture architecture.

 -i|--install

Install Debian packages (.deb) named on the command line. Only files in
the directories /lib, /usr/lib, /usr/X11R6/lib, /usr/include and 
/usr/X11R6/include are extracted, since only they can be relevant for
cross compiling. In the lib directories, also no subdirectories are
extracted.

 -A|--convert-anyway

Convert Debian package even if it does not provide any files useful for
cross-compile environment.

 -X|--exclude PACKAGE

Removes the specified package from the dependencies of the current
package. Typically used to drop dependencies on packages that are not
required within a cross-build environment, e.g. packages containing
only executables or architecture independent files.

dpkg-cross can only check the current package and information about a
dependency is not available (for that, use apt-cross). By default, 
dpkg-cross converts all dependencies to specify the cross version of
the dependency package.

If you know that a particular dependency should not be converted (it
provides no useful files or is architecture  independent), that
dependency can be excluded and dpkg-cross will remove that package from
the dependency information of the cross package. -X has replaced the use
of keepdeps and removedeps in /etc/dpkg-cross/cross-compile.

-X|--exclude PACKAGE needs to be repeated for each package to be excluded.

 -k|--keep-temp

Keep the built and installed package instead of deleting it. Useful with
apt-cross -k. Requires --install.

 -b|--build

Just build the converted Debian package, but do not install it with dpkg.

 -r|--remove

Remove the cross compiling packages named on the command line.

 -s|--status

Print status of the named packages.

 -l|--list

Print short version of status of named packages or package name patterns.

 -L|--list-files

List files belonging to the named packages.

 -u|--update

Update current cross-installation with Debian packages found in/under
the paths given as arguments. Will check all packages there if they are
installed already as cross-compiling packages and if they are really
updates. Those packages will be installed as with -i.

 -Q|--query

Much like --update, but just prints available update packages and does
not install them.

=cut

=head1 FILES

/etc/dpkg-cross/cross-compile defines some settings for dpkg-cross
and can be overridden by an optional file in your home directory:
$HOME/.dpkg-cross/cross-compile - see also apt-cross.

Only B<default_arch> is used routinely.

 default_arch (default: none)

The default architecture for dpkg-cross is normally set by debconf. 
To change the system-wide value, use:

 $ sudo dpkg-reconfigure dpkg-cross

Alternatively, the default can be overridden on a per-user basis using
the optional file in $HOME/.dpkg-cross/

Other values previously used in this file for legacy code are now
unsupported.

=cut

use POSIX;
use POSIX qw(:errno_h :signal_h);
use IO::Handle;
use File::Basename;
use Text::Wrap;
use Debian::DpkgCross;
use strict;
use warnings;
use vars qw($verbose $str @removedeps $package %builds $arch $exclude
@keepdeps $dpkg_statfile $progname $debname $anyway $cross2cross
$crossdir $crosslib $crosslib64 $crosslib32 $crossinc $data $len
$retval $dpkg_cmd $mode $pkg @exlist $conffile $removedeps $keepdeps
$DPKGCROSSVERSION $keep_temp);

$dpkg_statfile = "/var/lib/dpkg/status";
&read_config;
$arch = &get_architecture;
$DPKGCROSSVERSION = &get_version;
$progname = basename($0);

# packages to omit in dependencies
@removedeps = (); #&get_removedeps;
@keepdeps = ();   #&get_keepdeps;

sub usageversion {
    print(STDERR <<END)
dpkg-cross version $DPKGCROSSVERSION

Usage:
 dpkg-cross [OPTIONS] [--install|-i] <files...>
 dpkg-cross [OPTIONS] [--build|-b] <files...>
 dpkg-cross [OPTIONS] [--remove|--purge|-r] <packages...>
 dpkg-cross [OPTIONS] [--status|-s] <packages...>
 dpkg-cross [OPTIONS] [--list|-l] <packages...>
 dpkg-cross [OPTIONS] [--list-files|-L] <packages...>
 dpkg-cross [OPTIONS] [--query|-Q] <pkgpath>
 dpkg-cross [OPTIONS] [--update|-u] <pkgpath>

Commands:
 -?|-h|--help|--version: print this message.

Options:
 -a|--arch ARCH:       set architecture (default: defined in configuration file)
 -v|--verbose:         be verbose
 -q|--quiet:           be quiet
 -A|--convert-anyway:  convert package even if it does not provide any
                       development files
 -X|--exclude PACKAGE: Exclude this package from the dependency list of the
                       built package.
 -k|--keep-temp:       Keep the temporary archives when installing.

dpkg-cross installs or removes libraries and include files for
cross-compiling Debian packages. It reads /etc/dpkg-cross/cross-compile
to determine the base directory of the cross compiler installation, and
works in the subdirectories lib and include there.
END
        || die "$progname: failed to write usage: $!\n";
}

$verbose = 1;
$anyway = 0;
$exclude = 0;
$keep_temp = 0;
@exlist=();
%builds=();
$cross2cross = 1;
while( @ARGV ) {
	$_= shift( @ARGV );
	last if m/^--$/;
	if (!/^-/) {
		unshift(@ARGV,$_);
		last;
	}
	elsif (/^(-\?|-h|--help|--version)$/) {
	&usageversion();
		exit( 0 );
	}
	elsif (/^(-v|--verbose)$/) {
		$verbose = 2;
	}
	elsif (/^(-q|--quiet)$/) {
		$verbose = 0;
	}
	elsif (/^(-k|--keep-temp)$/) {
		$keep_temp = 1;
	}
	elsif (/^(-i|--install)$/) {
		die "$progname: Only one action can be specified!\n" if $mode;
		$mode = "install";
	}
	elsif (/^(-r|--remove|--purge)$/) {
		die "$progname: Only one action can be specified!\n" if $mode;
		$mode = "remove";
	}
	elsif (/^(-s|--status)$/) {
		die "$progname: Only one action can be specified!\n" if $mode;
		$mode = "status";
	}
	elsif (/^(-l|--list)$/) {
		die "$progname: Only one action can be specified!\n" if $mode;
		$mode = "list";
	}
	elsif (/^(-L|--listfiles)$/) {
		die "$progname: Only one action can be specified!\n" if $mode;
		$mode = "listfiles";
	}
	elsif (/^(-b|--build)$/) {
		die "$progname: Only one action can be specified!\n" if $mode;
		$mode = "build";
	}
	elsif (/^(-Q|--query)$/) {
		die "$progname: Only one action can be specified!\n" if $mode;
		$mode = "query";
	}
	elsif (/^(-u|--update)$/) {
		die "$progname: Only one action can be specified!\n" if $mode;
		$mode = "update";
	}
	elsif (/^(-a|--arch$)/) {
		$arch = shift(@ARGV);
		die "$progname: --arch needs an argument.\n" if (!($arch));
	}
	elsif (/^(-X|--exclude)$/) {
		$pkg = shift (@ARGV);
		die ("$progname: --exclude needs an argument.\n") if ($pkg =~ /^\-/);
		push @removedeps, $pkg;
	}
	elsif (/^(-A|--convert-anyway)$/) {
		$anyway = 1;
	}
	else {
		die "$progname: Unknown option $_.\n";
	}
}

if (!defined($mode) || (!@ARGV && $mode ne "list")) {
	die "$progname: Too few arguments.\n";
}

if (not defined ($arch)) {
	die "$progname: No default architecture has been set.\n";
}

if (!&check_arch($arch)) {
	die "$progname: Unrecognised architecture: $arch\n";
}
&setup;

$retval = 0;

if ($mode eq "query" || $mode eq "update") {
	my %update_list = get_update_list( @ARGV );
	if (!%update_list) {
		print "No updates available.\n";
		exit 0;
	}
	if ($mode eq "query") {
		print "Available updates:\n";
		foreach (sort keys %update_list) {
			print wrap('','',"$_ (from $update_list{$_}->{'Oldver'} to ",
				"$update_list{$_}->{'Newver'})\n");
		}
	}
	else {
		$mode = "install";
		@ARGV = ();
		foreach (sort keys %update_list) {
			push( @ARGV, $update_list{$_}->{'Path'} );
		}
	}
}

if ($mode eq "status") {
	$dpkg_cmd = "--status";
}
elsif ($mode eq "list") {
	unshift( @ARGV, "*" ) if !@ARGV; # list all packages if no arg given
	$dpkg_cmd = "--list";
}
elsif ($mode eq "listfiles") {
	$dpkg_cmd = "--listfiles";
}
elsif ($mode eq "remove") {
	$dpkg_cmd = "--purge";
}
elsif ($mode eq "install") {
	my( @debs, $deb );
	print "Converting packages:\n" if $verbose >= 2;
	&check_exclude(@ARGV);
	foreach $package ( keys %builds) {
		$deb = &sub_build( $package, "/tmp" );
		if ($deb) {
			push( @debs, "/tmp/$deb" );
		}
		else {
			$retval = 1;
		}
	}
	if (@debs) {
		print "Installing converted packages with dpkg\n" if $verbose >= 2;
		open( PIPE, "dpkg -i @debs 2>&1 |" );
		while( <PIPE> ) {
			if ($verbose == 1 && /^Unpacking (replacement )?(\S+)/) {
				print "Unpacking $2\n";
				next;
			}
			print if ($verbose >= 1 && /^Setting up/) ||
					 $verbose >= 2 ||
						!/^(\(Reading\sdatabase|
						Selecting\spreviously\sdeselected\spackage|
						Unpacking|
						Preparing\sto\sreplace|
						 Setting\sup)/xi;
		}
		close( PIPE );
		if ($?) {
			warn "dpkg -i failed.\n";
			$retval = 1;
		}
		if ($keep_temp == 0)
		{
			print "Removing tmp packages\n" if $verbose >= 2;
			if (unlink( @debs ) != @debs) {
				warn "Removing @debs failed: $!\n";
				$retval = 1;
			}
		}
	}
}
elsif ($mode eq "build") {
	&check_exclude(@ARGV);
	foreach $package ( keys %builds ) {
		print "Trying to build: $package\n" if ($verbose >= 2);
		$retval = 1 if !sub_build( $package, "." );
	}
}

if ($dpkg_cmd) {
	my $cmdline = "dpkg $dpkg_cmd " .
		join( " ", map( rewrite_pkg_name($_), @ARGV ));
	print "Calling $cmdline\n" if $verbose >= 2;
	system( $cmdline );
	$retval = $? >> 8;
}
exit $retval;

sub sub_build {
	my $package = shift(@_);
	my $debpath = shift(@_);
	my $multiarch;

	# first of all, check if the file exists
	if (not -r $package) {
		warn "$progname: cannot access $package: $!\n";
		return "";
	}

	print "Going to convert $package\n" if $verbose >= 2;
	my $nofailmsg = 0;

	# set the umask (it may be bad by default)
	umask(0022);

	my $tmpdir = &create_tmpdir('dpkg-cross');
	if (!$tmpdir) {
		warn "$progname: failed to create temporary directory: $!\n";
		return "";
	}
	my ($src, $dst) = ("$tmpdir/src", "$tmpdir/dst");
	if (!(mkdir("$tmpdir/src") && mkdir("$tmpdir/dst"))) {
		warn "$progname: failed to prepare temporary directory: $!\n";
		system("rm -rf $tmpdir");
		return "";
	}

	# remove tmp files on C-c
	$SIG{'INT'} = sub {
		print "Removing tmp files...\n" if $verbose >= 2;
		system "rm -rf $tmpdir";
		die "Interrupted.\n";
	};

	print "Extracting $package\n" if $verbose >= 2;

	# extract package to $src
	if (system("dpkg --extract $package $src && dpkg --control $package $src/DEBIAN") != 0) {
		goto fail;
	}

	print "Extracting information from control file\n" if $verbose >= 2;

	# extract useful information from control file
	if (!(open(CONTROL, "$src/DEBIAN/control"))) {
		warn "$progname: cannot open package control file: $!\n";
		goto fail;
	}
	my $field;
	my %control;
	while (<CONTROL>) {
		chomp;
		if (/^ /) {
			if (defined($field)) {
				$control{$field} .= ("\n" . $_);
			}
		} elsif (/^(\S+):\s*(.*)$/i) {
			$field = lc($1);
			$control{$field} = $2;
		}
	}
	close(CONTROL);

	# check for existance of required fields
	for $field (qw(package version architecture)) {
		if (!defined($control{$field})) {
			warn "$progname: required field \'$field\' missing in control file\n";
			goto fail;
		}
	}
	$multiarch = &check_multiarch ($control{"package"});
	$multiarch = "true" if (defined ($control{'multi-arch'}));
	# check for package already processed by dpkg-cross, or created by
	# cross-gcc compilation
	if (($control{"architecture"} eq "all") && (
	    ($control{"description"} =~ /generated by dpkg-cross/) ||
	    ($control{"description"} =~ /contains files for.*cross-compile/)
	   )) {
		warn "$progname: $package already looks as cross-compile package\n";
		goto fail;
	}

	# check package architecture
	my $control_arch = $control{"architecture"};
	if (($control_arch ne $arch) and 
		($control_arch ne "all")) {
		warn "$progname: $package has wrong architecture ($control_arch)\n";
		goto fail;
	}

	# prepare destination filename
	my $evers = $control{"version"};
	$evers =~ s/^\d+://;		 # strip epoch for filename
    $debname = $control{"package"} . "-" . $arch . "-cross_" . $evers . "_all.deb";

	# now ready to start preparing destination package

	print "Creating destination package tree\n" if $verbose >= 2;

	# Any files from usr/include and from usr/X11R6/include will go
	# to $crossinc. This should be OK even for X includes - most of those
	# are in X11 subdirectory, so they would go to $crossinc/X11.
	#
	# Also usr/src and usr/lib is searched for includes - files with
	# .h, .hh, .hpp extensions (case insensitive). New path for those
	# will be their original path with usr/ replaced by $crossdir/
	#
	# Library files - *.so* and *.a and *.o (+) files from lib, usr/lib and
	# usr/X11/lib. All those will go to $crosslib.
	# Other library files are not copied - they are probably not for
	# compile-time linking if they are in non-standard places, so there
	# is no rationale to put them into cross-compile support package.
	# (+) at least libc6-dev provides .o files in /usr/lib
	#
	# *.la files in library directories are also copied, and library
	# and paths are modified there. Same for usr/lib/pkgconfig/*.pc
	# files.
	#
	# Symlinks are copied (and modified appropriately) if their
	# destination is copied. Also, symlinks to non-existing shared libraries
	# are copied (this is common case for libdevel packages)
	#
	# Directories are created only to hold some files or symlinks.
	# No empty directiries are copied.

	my $objects = 0; # Number of objects (files and symlinks) in the converted package

	# Helper: create directory tree if it does not exist.
	sub ensure_dir {
		my $dir = $_[0];
		while ($dir =~ m:/:g) {
			next if (length($`) == 0);
			next if -d $`;
			if (! mkdir($`)) {
				warn "$progname: failed to create $`: $!\n";
				return 0;
			}
		}
		return 1;
	}

	# Helper: link a file
	sub link_file {
		my ($from, $to) = @_;
		ensure_dir($to) or return 0;
		if (! link($from, $to)) {
			warn "$progname: failed to link $from to $to: $!\n";
			return 0;
		}
		return 1;
	}

	# Helper: move a multiarch file to old location
	sub move_file {
		my ($from, $to) = @_;
		ensure_dir($to) or return 0;
		open (MOVE, "$from") or return 0;
		my @old=<MOVE>;
		close (MOVE);
		open (MOVE, ">$to") or return 0;
		print MOVE @old;
		close (MOVE);
		unlink ($from);
		return 1;
	}

	# Helper: detect ldscript
	# Assumes that any *.so* file in library directory that is not ELF is
	# ldscript
	sub is_ldscript {
		my $file = $_[0];
		if (! open( FILE, $file )) {
			warn "$progname: failed to open $file: $!\n";
			return 0;
		}
		$len = sysread( FILE, $data, 4 );
		close( FILE );
		return 0 if ($len != 4);
		return 0 if ($data =~ /^.ELF$/);
		return 1;
	}

	# Helper: fix ldscript.
	# Change any occurance of /lib, /usr/lib and /usr/X11R6/lib to $crosslib
	sub fix_ldscript {
		my ($from, $to) = @_;
		ensure_dir($to) or return 0;
		if (! open(FROM, $from)) {
			warn "$progname: failed to open $from: $!\n";
			return 0;
		}
		if (! open(TO, ">$to")) {
			warn "$progname: failed to open $to for writing: $!\n";
			close(FROM);
			return 0;
		}
		while (<FROM>) {
			s:(^|[^-\w/])(/usr(/X11R6)?)?/lib:$1$crosslib:g;
			print TO;
		}
		close(FROM);
		close(TO);
		return 1;
	}

	# Helper: fix .la file:
	# - set libdir to $crosslib
	# - change dependency_libs:
	#   - remove any -L (because dpkg-cross never allows any libraries
	#     outside $crosslib)
	#   - replace any references to .la files to files in $crosslib
	# To make this work both for $crosslib and $crosslib64, one of those is passed
	# as 3rd argument
	# Also adapted to work for $crosslib32
	sub fix_la_file {
		my ($from, $to, $crosslib) = @_;
		ensure_dir($to) or return 0;
		if (! open(FROM, $from)) {
			warn "$progname: failed to open $from: $!\n";
			return 0;
		}
		if (! open(TO, ">$to")) {
			warn "$progname: failed to open $to for writing: $!\n";
			close(FROM);
			return 0;
		}
		while (<FROM>) {
			if (/^libdir=/) {
				print TO "libdir=\'$crosslib\'\n";
			} elsif (/^dependency_libs='(.*)'$/ or /^dependency_libs=(.*)/) {
				my $deplibs = $1;
				$deplibs =~ s/( )?-L\S+//g;
				$deplibs =~ s:\S+/([\w\.\-]+\.la)( |$):$crosslib/$1$2:g;
				print TO "dependency_libs='$deplibs'\n";
			} else {
				print TO;
			}
		}
		close(FROM);
		close(TO);
		return 1;
	}

	# Helper: fix pkgconfig file
	# Set prefix and exec_prefix to $crossdir, libdir to $crosslib, includedir to $crossinc
	sub fix_pc_file {
		my ($from, $to) = @_;
		ensure_dir($to) or return 0;
		if (! open(FROM, $from)) {
			warn "$progname: failed to open $from: $!\n";
			return 0;
		}
		if (! open(TO, ">$to")) {
			warn "$progname: failed to open $to for writing: $!\n";
			close(FROM);
			return 0;
		}
		my $orig_prefix = '/usr';
		while (<FROM>) {
			# fix for #483076
			if ((m:^prefix="/usr(.*)"$:) or (m:^prefix=/usr(.*)$:)) {
				print TO "prefix=${crossdir}${1}\n";
				$orig_prefix = "/usr${1}";
			} elsif (/^exec_prefix=/) {
				print TO "exec_prefix=\${prefix}\n";
			} elsif (/^libdir=/) {
				if ($crosslib eq "$crossdir/lib") {
					print TO "libdir=\${exec_prefix}/lib\n";
				} else {
					print TO "libdir=$crosslib\n";
				}
			} elsif (/^datarootdir="\${prefix}(.*)"$/ or /^datarootdir=\${prefix}(.*)$/) {
				print TO "datarootdir=${orig_prefix}${1}\n";
			} elsif (m:\${exec_prefix}/bin:) {
				s:\${exec_prefix}/bin:${orig_prefix}/bin:;
				print TO;
			} elsif (/^includedir=/) {
				my $inc = ($crossinc eq "$crossdir/include") ? "\${prefix}/include" : $crossinc;
				s:\${(exec_)?prefix}/include:$inc:;
				print TO;
			} else {
				print TO;
			}
		}
		close(FROM);
		close(TO);
		return 1;
	}
	my $config = &get_config;
	my $crosstype = `CC="" dpkg-architecture -f -a$arch -qDEB_HOST_GNU_TYPE 2> /dev/null`;
	chomp ($crosstype);
	$crossinc = $$config{'crossinc'};
	$crossdir = $$config{'crossdir'};
	$crosslib = $$config{'crosslib'};
	$crosslib64 = $$config{'crosslib64'};
	$crosslib32 = $$config{'crosslib32'};
	# check for multiarch symlinks
	if (defined $multiarch)
	{
		open(PIPE, "find $src/ -type l -print |") or goto fail;
		while(<PIPE>) {
			chomp;
			s/^$src//;
			if (m:^/usr/lib/$crosstype/:) {
				# move symlink
				print "moving symlink $_.\n" if ($verbose >= 2);
				link_file ("$src$_", "$dst$crossinc/$'") or goto fail;
			}
		}
	}
	# Now process regular files ...
	open(PIPE, "find $src/ -type f -print |") or goto fail;
	while(<PIPE>) {
		chomp;
		s/^$src//;
		/^DEBIAN/ && next;
		# special support for generated cache data
		if (m:(/etc/dpkg-cross/cross-config.d/($arch)?/.*):) {
			&ensure_dir("$dst$1");
			if (! open(FROM, "$src$_")) {
				warn "$progname: failed to open $src$_: $!\n";
				return 0;
			}
			if (! open(TO, ">$dst$1")) {
				warn "$progname: failed to open $dst$1 for writing: $!\n";
				close(FROM);
				return 0;
			}
			while (<FROM>) {
				print TO;
			}
			close(FROM);
			close(TO);
		} elsif (m:^/usr(/share/.*/.*\.cmake)$:) {
			&ensure_dir("$dst/$crossdir/$1");
			if (! open(FROM, "$src$_")) {
				warn "$progname: failed to open $src$_: $!\n";
				return 0;
			}
			if (! open(TO, ">$dst/$crossdir/$1")) {
				warn "$progname: failed to open $dst$1 for writing: $!\n";
				close(FROM);
				return 0;
			}
			while (<FROM>) {
				print TO;
			}
			close(FROM);
			close(TO);
		} elsif (m:^/usr/include/$crosstype/:) {
			if (defined $multiarch) {
				# move file
				print "moving file $_.\n" if ($verbose >= 2);
				move_file ("$src$_", "$dst$crossinc/$'") or goto fail;
			} else {
				link_file("$src$_", "$dst$crossinc/$'") or goto fail;
			}
		} elsif (m:^/usr/lib/$crosstype/:) {
			if (defined $multiarch) {
				# move file
				print "moving file $_.\n" if ($verbose >= 2);
				move_file ("$src$_", "$dst$crossinc/$'") or goto fail;
			} else {
				link_file("$src$_", "$dst$crossinc/$'") or goto fail;
			}
		} elsif (m:^/usr(/X11R6)?/include/:) {
			# regular file under /usr/include or /usr/X11R6/include
			link_file("$src$_", "$dst$crossinc/$'") or goto fail;
		} elsif (m:^/usr/(lib/.*\.([hH]|[hH][hH]|[hH][pP][pP]))$:) {
			# regular .h, .hh, or .hpp file under /usr/lib
			link_file("$src$_", "$dst$crossdir/$1") or goto fail;
		} elsif (m:^/usr(/X11R6)?/lib/([^/]+\.[ao])$:) {
			# regular .a or .o file under /usr/lib or /usr/X11R6/lib
			link_file("$src$_", "$dst$crosslib/$2") or goto fail;
		} elsif (m:^/usr(/X11R6)?/lib64/([^/]+\.[ao])$:) {
			# regular .a or .o file under /usr/lib64 or /usr/X11R6/lib64
			link_file("$src$_", "$dst$crosslib64/$2") or goto fail;
		} elsif (m:^/usr(/X11R6)?/lib32/([^/]+\.[ao])$:) {
			# regular .a or .o file under /usr/lib32 or /usr/X11R6/lib32
			link_file("$src$_", "$dst$crosslib32/$2") or goto fail;
		} elsif ((m:^/emul/ia32-linux/usr/lib/([^/]+\.[ao])$:)) {
			# regular .a or .o file under /emul/ia32-linux/
			# for #463588
			link_file("$src$_", "$dst$crosslib32/$1") or goto fail;
		} elsif (m:^(/usr(/X11R6)?)?/lib/([^/]+\.so[^/]*)$:) {
			# regular .so* file under /lib, /usr/lib or /usr/X11R6/lib
			if (is_ldscript("$src$_")) {
				fix_ldscript("$src$_", "$dst$crosslib/$3") or goto fail;
			} else {
				link_file("$src$_", "$dst$crosslib/$3") or goto fail;
			}
		} elsif (m:^/usr/\w+-\w+(-\w+(-\w+)?)?/(lib|include)/:) {
			# regular file under /usr/<host>/lib or include
			if ($cross2cross) {
				link_file("$src$_", "$dst$_");
			} else {
				next;
			}
		} elsif (m:^(/usr(/X11R6)?)?/lib64/([^/]+\.so[^/]*)$:) {
			# regular .so* file under /lib64, /usr/lib64 or /usr/X11R6/lib64
			if (is_ldscript("$src$_")) {
				fix_ldscript("$src$_", "$dst$crosslib64/$3") or goto fail;
			} else {
				link_file("$src$_", "$dst$crosslib64/$3") or goto fail;
			}
		} elsif (m:^(/usr(/X11R6)?)?/lib32/([^/]+\.so[^/]*)$:) {
			# regular .so* file under /lib32, /usr/lib32 or /usr/X11R6/lib32
			if (is_ldscript("$src$_")) {
				fix_ldscript("$src$_", "$dst$crosslib32/$3") or goto fail;
			} else {
				link_file("$src$_", "$dst$crosslib32/$3") or goto fail;
			}
		} elsif ((m:^/emul/ia32-linux/usr/lib/([^/]+\.so[^/]*)$:)) {
			# regular .so* file under /emul/ia32-linux/usr/lib
			if (is_ldscript("$src$_")) {
				fix_ldscript("$src$_", "$dst$crosslib32/$1") or goto fail;
			} else {
				link_file("$src$_", "$dst$crosslib32/$1") or goto fail;
			}
		} elsif (m:^/usr(/X11R6)?/lib/([^/]+\.la)$:) {
			# regular .la file under /usr/lib or /usr/X11R6/lib
			fix_la_file("$src$_", "$dst$crosslib/$2", $crosslib) or goto fail;
		} elsif (m:^/usr(/X11R6)?/lib64/([^/]+\.la)$:) {
			# regular .la file under /usr/lib64 or /usr/X11R6/lib64
			fix_la_file("$src$_", "$dst$crosslib64/$2", $crosslib64) or goto fail;
		} elsif (m:^/usr(/X11R6)?/lib32/([^/]+\.la)$:) {
			# regular .la file under /usr/lib32 or /usr/X11R6/lib32
			fix_la_file("$src$_", "$dst$crosslib32/$2", $crosslib32) or goto fail;
		} elsif ((m:^/emul/ia32-linux/usr/lib/([^/]+\.la)$:)) {
			# regular .la file under /emul-ia32-linux/usr/lib/
			fix_la_file("$src$_", "$dst$crosslib32/$1", $crosslib32) or goto fail;
		} elsif (m:/usr/lib/(pkgconfig/[^/]+.pc)$:) {
			# regular .pc file in /usr/lib/pkgconfig
			fix_pc_file("$src$_", "$dst$crosslib/$1") or goto fail;
			# not for lib64: I don't know if there is any rationale
		} elsif (m:/usr/(share/pkgconfig/[^/]+.pc)$:) {
			# regular .pc file in /usr/share/pkgconfig
			fix_pc_file("$src$_", "$dst$crossdir/$1") or goto fail;
		} elsif (m:^/usr/(src/.*):) {
			# any files under /usr/src/
			link_file("$src$_", "$dst$crossdir/$1") or goto fail;
		} elsif (m:^/usr/(lib/debug/.*):) {
			# any files under /usr/lib/debug
			link_file("$src$_", "$dst$crossdir/$1") or goto fail;
		} elsif (m:^/usr/(share/fonts/.*):) {
			# any files under /usr/share/fonts/
			link_file("$src$_", "$dst$crossdir/$1") or goto fail;
		} else {
			# everything else
			next;
		}

		$objects++;
	}
	close(PIPE);

	# Helper: create shortest relative symlink
	sub create_relative {
		my ($from, $to) = @_;
		# First remove common prefix from $from and $to
		while (1) {
			$from =~ m:^(/[^/]+): or last;
			my ($p1, $s1) = ($1, $');
			$to =~ m:^(/[^/]+): or last;
			my ($p2, $s2) = ($1, $');
			last if ($p1 ne $p2);
			($from, $to) = ($s1, $s2);
		}
		# Now $from one more slashes than "../"'s should be added before $to
		# Example: /usr/lib/a/b -> /usr/lib/c
		# After loop: $from is "/a/b", $to is "/c"
		# $from has 2 slashes, so one "../" should be added before $to
		# Result is: /usr/lib/a/b -> ../c
		$from =~ s:[^/]::g;	# remove all but slashes
		$from =~ s:^/::;	# remove first slash (at least one slash always exists)
		$from =~ s:/:../:g;	# replace each of other slashes with ../
		$to =~ s:^/::;		# remove leading slash from $to
		return $from . $to;
	}

	# ... next process symlinks.
	open(PIPE, "find $src/ -type l -print |") or goto fail;
	while(<PIPE>) {
		chomp;
		s/^$src//;
		# Ignore any symlinks not under /usr or /lib or /lib64
		m:^/(usr|lib|lib64|emul/ia32-linux): or next;
		next if (m:^/usr/\w+-\w+(-\w+(-\w+)?)?/: && !$cross2cross);
		# Find out (absolute) symlink destination
		my $lv = readlink("$src$_");
		if ($lv ne "." && $lv =~ m:^[^/]:) {
			m:^(.*)/[^/]*$:;
			$lv = "$1/$lv";
		}
		# Ignore any symlinks pointing outside /usr and /lib and /lib64
		$lv =~ m:^/(usr|lib|lib64|emul/ia32-linux): or next;

		# Calculate corresponding DESTINATION path
		$lv = convert_path($lv);

		# Check if destination object exists.
		# FIXME: this code is not correct for the case of symlink chains.
		#        If converting symlink chains will be ever needed, this
		#        should be rewritten
		if (! -e "$dst$lv") {
			# Non-existing destination allowed only if it is .so link,
			# or if both source and destination is under /usr/src
			next unless (/.*\.so$/ or
					(m:/usr/src/: and $lv =~ m:/usr/:));
		}

		# Calculate corresponding SOURCE path
		$_ = convert_path($_);

		# Skip links that are going to point to themselves
		# Example is /usr/include/X11 -> ../X11R6/include/X11:
		# both source and destination here will be converted to $crossinc/X11
		next if ($lv eq $_);

		# skip links to private modules and plugins that are not
		# useful or packaged in the -cross package, basically anything
		# in a directory beneath /usr/lib/. See #499292
		# except pkgconfig symlinks, see #506956
		next if (($lv =~ m:$crosslib/.*/:) and ($lv !~ m:$crosslib/pkgconfig/:));
		$lv =~ m:$crosslib/(.*)$:;
		print "Creating symlink $_ -> $1\n" if ($verbose >= 2);

		# Skip if destination already exists - for the case if a symlink maps
		# to same destination as a regular file
		next if (-e "$dst$_");

		# Previous line seems not to catch situation when "$dst$_" is a symlink
		# pointing to non-existant (external to the package being created) file
		unlink("$dst$_");

		# Create a relative link
		my $relative = create_relative($_, $lv);
		ensure_dir("$dst$_") or goto fail;
		if (! symlink($relative, "$dst$_")) {
			warn "$progname: failed to create symlink $dst$_ -> $relative: $!\n";
			goto fail;
		}
		$objects++;
	}
	close(PIPE);

	# At this point, $dst should be ready, and $objects should contain number
	# or files and symlinks under $dst
	# allow empty multiarch files without comment
	if ($objects == 0 and (not defined $multiarch)) {
		if ($anyway) {
			print wrap('','',"$progname: package " . $control{"package"} .
				" doesn't provide any useful files, but processing" .
				" it anyway as requested\n") if ($verbose >= 1);
		} else {
			warn "$progname: package " . $control{"package"} .
				" doesn't provide any useful files. Skipping.\n";
			$nofailmsg = 1;
			goto fail;
		}
	}

	if (not defined $multiarch)
	{
		# Create README in /usr/share/doc/ ...
		my $docpath = "/usr/share/doc/" . $control{"package"} . "-$arch-cross";
		my $docfile = "$docpath/README";
		print "Creating $docfile\n" if $verbose >= 2;
		ensure_dir("$dst$docfile") or goto fail;
		if (! open(DOC, ">$dst$docfile")) {
			warn "$progname: failed to open $dst$docfile for writing: $!\n";
			goto fail;
		}
		print DOC "Package " . $control{"package"} .
				"-$arch-cross is a part of cross-compile environment \n" .
				"for $arch target. It was created from " . $control{"package"} .
				" package using dpkg-cross tool.\n\nTo get more information about " .
				$control{"package"} . " or dpkg-cross packages,\n" .
				"please install those and read provided documentation.\n";
		close(DOC);
	}

	if (! mkdir("$dst/DEBIAN")) {
		warn "$progname: failed to create $dst/DEBIAN: $!\n";
		goto fail;
	}

	# Link the shlibs file
	if (-f "$src/DEBIAN/shlibs") {
		print "Installing shlibs file\n" if $verbose >= 2;
		link_file("$src/DEBIAN/shlibs", "$dst/DEBIAN/shlibs");
	}

	# Create the control file.
	print "Creating control file\n" if $verbose >= 2;
	if (! open(CONTROL, ">$dst/DEBIAN/control")) {
		warn "$progname: failed to open $dst/DEBIAN/control for writing: $!\n";
		goto fail;
	}

	print CONTROL "Package: " . $control{"package"} . "-$arch-cross\n";
	print CONTROL "Version: " . $control{"version"} . "\n";
	print CONTROL "Section: devel\n";
	print CONTROL "Priority: extra\n";
	print CONTROL "Architecture: all\n";

	if (defined($control{"maintainer"})) {
		print CONTROL "Maintainer: " . $control{"maintainer"} . "\n";
	}
	if (defined($control{"source"})) {
		print CONTROL "Source: " . $control{"source"} . "\n";
	}
	else
 	{
		print CONTROL "Source: " . $control{"package"} . "\n";
	}

	# Turn Pre-Depends into Depends
	if (defined($control{"pre-depends"})) {
		if (defined($control{"depends"})) {
			$control{"depends"} = $control{"pre-depends"} . ", " . $control{"depends"};
		} else {
			$control{"depends"} = $control{"pre-depends"};
		}
	}

	# Rewrite dependency fields
	# Make 'provides' field to exist always to all $package-$arch-dcv1
	# but create no dependencies on dcv1 - see #514249
	$control{"provides"} = "" unless defined $control{"provides"};
	for $field qw(depends conflicts provides replaces) {
		next if not defined $control{$field};
		print CONTROL ucfirst($field) . ": ".$control{"package"} ."-$arch-dcv1\n"
			if ($field eq "provides");
		my $rewritten = rewrite_dependencies($control{$field});
		if (length($rewritten) > 0) {
			# Capitalize first letter of field name
			print CONTROL ucfirst($field) . ": " . $rewritten . "\n";
		}
	}

	print CONTROL "X-Multiarch: delete\n"
		if (defined $multiarch);

	# Output modified description
	if (defined ($multiarch))
	{
		print CONTROL "Description: " . $control{"package"} . " - multiarch zombie package\n";
		print CONTROL " This package was generated by dpkg-cross as a zombie multiarch package.\n" .
			" .\n Remove this package when there are no reverse dependencies left.\n"
	}
	elsif (defined($control{"description"})) {
		$control{"description"} =~ /(.*)/; # match first line
		print CONTROL "Description: $1 (for cross-compiling)\n";
		print CONTROL " This package was generated by dpkg-cross for cross compiling.\n .$'\n";
	} else {
		print CONTROL "Description: " . $control{"package"} . " for cross-compiling\n";
		print CONTROL " This package was generated by dpkg-cross for cross compiling.\n" .
			" .\n Source package " . $control{"package"} . " provided no description.\n"
	}

	close(CONTROL);

	# Create md5sums file
	print "Creating md5sums file\n" if $verbose >= 2;
	# Code shamelessly stolen from dh_md5sums
	system("cd $dst && find . -type f ! -regex '.*/DEBIAN/.*' -printf '%P\\0' | xargs -r0 md5sum > $dst/DEBIAN/md5sums");

	# Find out if fakeroot is needed and if it is available
	my $wrapper = "";
	if (geteuid() != 0) {
		$wrapper = "/usr/bin/fakeroot";
		if (! -x $wrapper) {
			warn "$progname: $wrapper is not available, package files will not be owned by root\n";
			$wrapper = "";
		}
	}

	# Build the .deb
	print "Building $debname\n" if $verbose == 1;
	# remove from the output that multiarch warnings which
	# dpkg-deb itself ignores.
	my $ignore = (defined $multiarch) ? "2>/dev/null" : "";
	if (system( "$wrapper dpkg-deb -b $dst $debpath $ignore")) {
		warn "$progname: building package with dpkg-deb -b failed.\n";
		goto fail;
	}

	$SIG{'INT'} = 'DEFAULT';
	system "rm -rf $tmpdir";
	return $debname;

fail:
	system("rm -rf $tmpdir");
	$SIG{'INT'} = 'DEFAULT';
	warn "$progname: conversion of $package failed.\n" unless $nofailmsg;
	return "";
}

sub get_update_list {
	my( %installed, %available, %av_path, $pkg, %update_list, $cnt );
	local( *F );

	if ($verbose >= 2) {
		print "Determining installed packages ";
		STDOUT->flush();
	}
	open( F, "<$dpkg_statfile" ) or die "Can't open $dpkg_statfile: $!";
	%installed = parse_pkg_list();
	if ($verbose >= 2) {
		$cnt = %installed;
		$cnt = $cnt+0;
		print "($cnt packages)\n";
	}

	foreach (@_) {
		scan_available( \%available, \%av_path, $_ );
	}

	foreach $pkg (keys %installed) {
		if (exists($available{$pkg}) &&
			version_less_p( $installed{$pkg}, $available{$pkg} )) {
			$update_list{$pkg}->{'Path'} = $av_path{$pkg};
			$update_list{$pkg}->{'Oldver'} = $installed{$pkg};
			$update_list{$pkg}->{'Newver'} = $available{$pkg};
		}
	}
	return %update_list;
}

sub scan_available {
	my $av_ref = shift;
	my $path_ref = shift;
	my $pkgpath = shift;
	my( @pkglist, %available, $file, $pkg, $cnt );

	if ($verbose >= 2) {
		print "Scanning .deb files under $pkgpath ";
		STDOUT->flush();
	}
	@pkglist = `find $pkgpath -type f -a -name '*.deb' -print`;
	die "find command returned error status $?\n" if $?;
	if (!@pkglist) {
		print "No .deb files found under $pkgpath\n" if $verbose >= 1;
		return;
	}
	chomp @pkglist;

	foreach $file (@pkglist) {
		open( F, "dpkg --field $file |" )
			or die "Can't run dpkg --field $file: $!\n";
		if (%available = parse_pkg_list(1)) {
			$pkg = (keys %available)[0];
			$av_ref->{$pkg} = $available{$pkg};
			$path_ref->{$pkg} = $file;
			++$cnt;
		}
	}
	print "($cnt packages)\n" if $verbose >= 2;
}

sub parse_pkg_list {
	my $avail_pkg = shift;
	my( $name, $version, %result );
	local($/) = ""; # read in paragraph mode

	while( <F> ) {
		/^Package:\s*(\S+)\s*$/mi || next; $name = $1;
		if ($avail_pkg) {
			# available package: check architecture
			/^Architecture:\s*(\S+)\s*$/mi || next;
			next if $1 ne $arch;
		}
		else {
			# package from status file: check if installed at all, and
			# if cross-compiling package; strip suffix from name
			next if /^Status:.*\s+(\S+)\s*$/mi && $1 ne 'installed';
			next if $name !~ /-$arch-cross$/;
			$name =~ s/-$arch-cross$//;
		}
		/^Version:\s*(\S+)\s*$/mi || next; $version = $1;
		$result{$name} = $version;
	}
	close( F ) or die "Error status from dpkg\n";;
	return %result;
}

sub version_less_p {
	my $vers1 = shift;
	my $vers2 = shift;

	system( "dpkg --compare-versions $vers1 '<<' $vers2" );
	return $? == 0;
}

sub rewrite_dependencies {
	my $str = shift;

	my @list = map( rewrite_alternatives($_), split( /\s*,\s*/, $str));
	# remove empty elements
	@list = map { $_ ? ( $_ ) : () } @list;
	return join(", ", @list );
}

sub rewrite_alternatives {
	my $str = shift;

	my @list = map( rewrite_item($_), split( /\s*\|\s*/, $str ));
	# if any of the alternatives became empty (because of @removedeps),
	# the complete dependency should be removed
	@list = ();
	for my $item (split( /\s*\|\s*/, $str )) {
		$item = rewrite_item($item);
		return () if not $item;
		push @list, $item
	}
	return join( " | ", @list );
}

sub rewrite_item {
	my $str = shift;
	$str =~ /^([^ (]+)/;
	my $name = $1;
	return () if grep { $_ eq $name } @removedeps;
	return $str if grep { $_ eq $name } @keepdeps;
	$str =~ s/^([^ (]+)/$name-$arch-cross/
		if (not defined &check_multiarch ($name));
	return $str;
}

sub check_exclude
{
	foreach $package ( @ARGV ) {
		if ($package =~ /^\-X/)
		{
			$exclude = 1;
			next;
		}
		if (($exclude == 1) && ($package !~ /^\-/) && (!defined $builds{$package}))
		{
			push @removedeps, $package;
			next;
		}
		$builds{"$package"}++;
	}
	$str = join(' ', @removedeps);
	print wrap('','',"Excluding: $str\n") if ($verbose >= 2);
}

=head1 Multiarch behaviour

=head2 Files

F</etc/dpkg-cross/multiarch-cross.d/>

Any file in this directory will be expected to contain a simple list
of binary package names which are multiarch-compliant for all uses of
dpkg-cross on that system.

apt-cross includes a helper script to identify these packages 
(F</usr/share/apt-cross/update-multiarch.pl> or you can use:

 grep-aptavail -s Package -F Multi-Arch same
 grep-aptavail -s Package -F Multi-Arch foreign
 grep-aptavail -s Package -F Multi-Arch allowed

See:

 https://wiki.ubuntu.com/MultiarchSpec

=head2 Constraints

=over

=item *

Absolute and total reliance on the accuracy of a config file created,
updated and maintained by a separate process, e.g. update-multiarch.pl
from apt-cross.

=item *

If this package name exists in that config file, create a multiarch version

=item *

multiarch versions have NO files in the package of any kind.

=item *

multiarch versions have a mangled description indicating a zombie package

=item *

multiarch versions depend on the multiarch native package, i.e.
libfoo-ARCH-cross depends on libfoo at or greater than the version
of libfoo that first includes multiarch support.

=item *

multiarch versions include a new control field: X-Multiarch: delete

=back

=cut

sub check_multiarch
{
	my ($m, $mstr, @malist, $pkg);
	$pkg = shift;
	$m = &read_multiarch_list();
	@malist = @$m if (defined $m);
	$mstr = join (" ", sort @malist);
	return ($mstr =~ /$pkg/) ? "skip" : undef;
}
