#!/usr/bin/perl

#- Mandrake Simple Archive Extracter.
#- Copyright (C) 1999 MandrakeSoft (fpons@mandrakesoft.com)
#-
#- 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, 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

#- Simple cat archive with gzip/bzip2 for perl.
#- see build_archive for more information.
#-
#- uncompressing sheme is:
#-         | |
#-         | |                                        | |
#-  $off1 =|*| }                                      | |
#-         |*| }                               $off2 =|+| }
#-         |*| } $siz1   =>   'gzip/bzip2 -d'   =>    |+| } $siz2  => $filename
#-         |*| }                                      |+| }
#-         |*| }                                      | |
#-         | |                                        | |
#-         | |                                        | |
#-         | |

#+use strict qw(subs vars refs);

#- used for uncompressing archive and other.
my %toc_trailer;
my @data;
my %data;

#- taken from DrakX common stuff, for conveniance and modified to match our expectation.
sub dirname { @_ == 1 or die "usage: dirname <name>\n"; local $_ = shift; s|[^/]*/*\s*$||; s|(.)/*$|$1|; $_ || '.' }
sub basename { @_ == 1 or die "usage: basename <name>\n"; local $_ = shift; s|/*\s*$||; s|.*/||; $_ }
sub mkdir_ {
    my $root = dirname $_[0];
    if (-e $root) {
	-d $root or die "mkdir: error creating directory $_[0]: $root is a file and i won't delete it\n";
    } else {
	mkdir_($root);
    }
    -d $_[0] and return;
    mkdir $_[0], 0755 or die "mkdir: error creating directory $_: $!\n";
}
sub symlink_ { mkdir_ dirname($_[1]); unlink $_[1]; symlink $_[0], $_[1] }

#- compute the closure of filename list according to symlinks or directory
#- contents inside the archive.
sub compute_closure {
    my %file;
    my @file;

    #- keep in mind when a filename already exist and remove doublons.
    @file{@_} = ();

    #- navigate through filename list to follow symlinks.
    do {
	@file = grep { !$file{$_} } keys %file;
	foreach (@file) {
	    my $file = $_;

	    #- keep in mind this one has been processed and does not need
	    #- to be examined again.
	    $file{$file} = 1;

	    exists $data{$file} or next;

	    for ($data{$file}[0]) {
		#- on symlink, try to follow it and mark %file if
		#- it is still inside the archive contents.
		/l/ && do {
		    my ($source, $target) = ($file, $data{$file}[1]);

		    $source =~ s|[^/]*$||; #- remove filename to navigate directory.
		    if ($source) {
			while ($target =~ s|^\./|| || $target =~ s|//+|/| || $target =~ s|/$|| or
			       $source and $target =~ s|^\.\./|| and $source =~ s|[^/]*/$||) {}
		    }

		    #- FALL THROUGH with new selection.
		    $file = $target =~ m|^/| ? $target : $source.$target;
		};

		#- on directory, try all files on data starting with
		#- this directory, provided they are not already taken
		#- into account.
		/[ld]/ && do {
		    @file{grep { !$file{$_} && m|^$file$| || m|^$file/| } keys %data} = ();
		    last;
		};
	    }
	}
    } while (@file > 0);

    keys %file;
}

#- read toc at end of archive.
sub read_toc {
    my ($file) = @_;
    my ($toc, $toc_trailer, $toc_size);
    my @toc_str;
    my @toc_data;

    local *ARCHIVE;
    open ARCHIVE, "<$file" or die "cannot open archive file $file\n";

    #- seek to end of file minus 64, size of trailer.
    #- read toc_trailer, check header/trailer for version 0.
    seek ARCHIVE, -64, 2;
    read ARCHIVE, $toc_trailer, 64 or die "cannot read toc_trailer of archive file $file\n";
    @toc_trailer{qw(header toc_d_count toc_l_count toc_f_count toc_str_size uncompress trailer)} =
	unpack "a4NNNNZ40a4", $toc_trailer;
    $toc_trailer{header} eq 'cz[0' && $toc_trailer{trailer} eq '0]cz' or die "bad toc_trailer in archive file $file\n";

    #- read toc, extract data hashes.
    $toc_size = $toc_trailer{toc_str_size} + 16*$toc_trailer{toc_f_count};
    seek ARCHIVE, -64-$toc_size, 2;

    #- read strings separated by \n, so this char cannot be inside filename, oops.
    read ARCHIVE, $toc, $toc_trailer{toc_str_size} or die "cannot read toc of archive file $file\n";
    @toc_str = split "\n", $toc;

    #- read data for file.
    read ARCHIVE, $toc, 16*$toc_trailer{toc_f_count} or die "cannot read toc of archive file $file\n";
    @toc_data = unpack "N". 4*$toc_trailer{toc_f_count}, $toc;

    close ARCHIVE;

    foreach (0..$toc_trailer{toc_d_count}-1) {
	my $file = $toc_str[$_];
	push @data, $file;
	$data{$file} = [ 'd' ];
    }
    foreach (0..$toc_trailer{toc_l_count}-1) {
	my ($file, $symlink) = ($toc_str[$toc_trailer{toc_d_count}+2*$_],
				$toc_str[$toc_trailer{toc_d_count}+2*$_+1]);
	push @data, $file;
	$data{$file} = [ 'l', $symlink ];
    }
    foreach (0..$toc_trailer{toc_f_count}-1) {
	my $file = $toc_str[$toc_trailer{toc_d_count}+2*$toc_trailer{toc_l_count}+$_];
	push @data, $file;
	$data{$file} = [ 'f', @toc_data[4*$_ .. 4*$_+3] ];
    }

    scalar keys %data == $toc_trailer{toc_d_count}+$toc_trailer{toc_l_count}+$toc_trailer{toc_f_count} or
	die "mismatch count when reading toc, bad archive file $file\n";
}

sub catsksz {
    my ($input, $seek, $siz, $output) = @_;
    my ($buf, $sz);

    while (($sz = sysread($input, $buf, $seek > 4096 ? 4096 : $seek))) {
	$seek -= $sz;
	last unless $seek > 0;
    }
    while (($sz = sysread($input, $buf, $siz > 4096 ? 4096 : $siz))) {
	$siz -= $sz;
	syswrite($output, $buf);
	last unless $siz > 0;
    }
}

sub main {
    my ($archivename, $dir, @file) = @_;
    my %extract_table;

    #- update %data according to TOC of archive.
    read_toc($archivename);

    #- as a special features, if both $dir and $file are empty, list contents of archive.
    if (!$dir && !@file) {
	my $count = scalar keys %data;
	print "$count files in archive, uncompression method is \"$toc_trailer{uncompress}\"\n";
	foreach my $file (@data) {
	    for ($data{$file}[0]) {
		/l/ && do { printf "l %13c %s -> %s\n", ' ', $file, $data{$file}[1]; last; };
		/d/ && do { printf "d %13c %s\n", ' ', $file; last; };
		/f/ && do { printf "f %12d %s\n", $data{$file}[4], $file; last; };
	    }
	}
	exit 0;
    }

    #- compute closure.
    @file = compute_closure(@file);

    foreach my $file (@file) {
	#- check for presence of file, but do not abort, continue with others.
	$data{$file} or do { print STDERR "unable to find file $file in archive $archivename\n"; next };

	my $newfile = "$dir/$file";

	print "extracting $file\n";
	for ($data{$file}[0]) {
	    /l/ && do { symlink_ $data{$file}[1], $newfile; last; };
	    /d/ && do { mkdir_ $newfile; last; };
	    /f/ && do {
		mkdir_ dirname $newfile;
		$extract_table{$data{$file}[1]} ||= [ $data{$file}[2], [] ];
		push @{$extract_table{$data{$file}[1]}[1]}, [ $newfile, $data{$file}[3], $data{$file}[4] ];
		$extract_table{$data{$file}[1]}[0] == $data{$file}[2] or die "mismatched relocation in toc\n";
		last;
	    };
	    die "unknown extension \"$_\" when uncompressing archive $archivename\n";
	}
    }

    #- delayed extraction is done on each block for a single  execution
    #- of uncompress executable.
    foreach (sort { $a <=> $b } keys %extract_table) {
	local *OUTPUT;
	if (open OUTPUT, "-|") {
	    #- $curr_off is used to handle the reading in a pipe and simulating
	    #- a seek on it as done by catsksz, so last file position is
	    #- last byte not read (ie last block read start + last block read size).
	    my $curr_off = 0;
	    foreach (sort { $a->[1] <=> $b->[1] } @{$extract_table{$_}[1]}) {
		my ($newfile, $off, $siz) = @$_;
		local *FILE;
		open FILE, $dir ? ">$newfile" : ">&STDOUT";
		catsksz(\*OUTPUT, $off - $curr_off, $siz, \*FILE);
		$curr_off = $off + $siz;
	    }
	} else {
	    local *BUNZIP2;
	    open BUNZIP2, "| $toc_trailer{uncompress}";
	    local *ARCHIVE;
	    open ARCHIVE, "<$archivename" or die "cannot open archive $archivename\n";
	    catsksz(\*ARCHIVE, $_, $extract_table{$_}[0], \*BUNZIP2);
	    exit 0;
	}
    }
}

main(@ARGV);