Format mostly used by Google Chrome and various Android apps to store resources such as translated strings, help messages and images.
This page hosts a formal specification of Chrome PAK serialization format using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
use strict;
use warnings;
use IO::KaitaiStruct 0.009_000;
########################################################################
package ChromePak;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
our $ENCODINGS_BINARY = 0;
our $ENCODINGS_UTF8 = 1;
our $ENCODINGS_UTF16 = 2;
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{version} = $self->{_io}->read_u4le();
if ($self->version() == 4) {
$self->{num_resources_v4} = $self->{_io}->read_u4le();
}
$self->{encoding} = $self->{_io}->read_u1();
if ($self->version() == 5) {
$self->{v5_part} = ChromePak::HeaderV5Part->new($self->{_io}, $self, $self->{_root});
}
$self->{resources} = ();
my $n_resources = ($self->num_resources() + 1);
for (my $i = 0; $i < $n_resources; $i++) {
push @{$self->{resources}}, ChromePak::Resource->new($self->{_io}, $self, $self->{_root});
}
$self->{aliases} = ();
my $n_aliases = $self->num_aliases();
for (my $i = 0; $i < $n_aliases; $i++) {
push @{$self->{aliases}}, ChromePak::Alias->new($self->{_io}, $self, $self->{_root});
}
}
sub num_resources {
my ($self) = @_;
return $self->{num_resources} if ($self->{num_resources});
$self->{num_resources} = ($self->version() == 5 ? $self->v5_part()->num_resources() : $self->num_resources_v4());
return $self->{num_resources};
}
sub num_aliases {
my ($self) = @_;
return $self->{num_aliases} if ($self->{num_aliases});
$self->{num_aliases} = ($self->version() == 5 ? $self->v5_part()->num_aliases() : 0);
return $self->{num_aliases};
}
sub version {
my ($self) = @_;
return $self->{version};
}
sub num_resources_v4 {
my ($self) = @_;
return $self->{num_resources_v4};
}
sub encoding {
my ($self) = @_;
return $self->{encoding};
}
sub v5_part {
my ($self) = @_;
return $self->{v5_part};
}
sub resources {
my ($self) = @_;
return $self->{resources};
}
sub aliases {
my ($self) = @_;
return $self->{aliases};
}
########################################################################
package ChromePak::HeaderV5Part;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{encoding_padding} = $self->{_io}->read_bytes(3);
$self->{num_resources} = $self->{_io}->read_u2le();
$self->{num_aliases} = $self->{_io}->read_u2le();
}
sub encoding_padding {
my ($self) = @_;
return $self->{encoding_padding};
}
sub num_resources {
my ($self) = @_;
return $self->{num_resources};
}
sub num_aliases {
my ($self) = @_;
return $self->{num_aliases};
}
########################################################################
package ChromePak::Resource;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{id} = $self->{_io}->read_u2le();
$self->{ofs_body} = $self->{_io}->read_u4le();
}
sub len_body {
my ($self) = @_;
return $self->{len_body} if ($self->{len_body});
if ($self->has_body()) {
$self->{len_body} = (@{$self->_parent()->resources()}[($self->idx() + 1)]->ofs_body() - $self->ofs_body());
}
return $self->{len_body};
}
sub body {
my ($self) = @_;
return $self->{body} if ($self->{body});
if ($self->has_body()) {
my $_pos = $self->{_io}->pos();
$self->{_io}->seek($self->ofs_body());
$self->{body} = $self->{_io}->read_bytes($self->len_body());
$self->{_io}->seek($_pos);
}
return $self->{body};
}
sub id {
my ($self) = @_;
return $self->{id};
}
sub ofs_body {
my ($self) = @_;
return $self->{ofs_body};
}
sub idx {
my ($self) = @_;
return $self->{idx};
}
sub has_body {
my ($self) = @_;
return $self->{has_body};
}
########################################################################
package ChromePak::Alias;
our @ISA = 'IO::KaitaiStruct::Struct';
sub from_file {
my ($class, $filename) = @_;
my $fd;
open($fd, '<', $filename) or return undef;
binmode($fd);
return new($class, IO::KaitaiStruct::Stream->new($fd));
}
sub new {
my ($class, $_io, $_parent, $_root) = @_;
my $self = IO::KaitaiStruct::Struct->new($_io);
bless $self, $class;
$self->{_parent} = $_parent;
$self->{_root} = $_root || $self;;
$self->_read();
return $self;
}
sub _read {
my ($self) = @_;
$self->{id} = $self->{_io}->read_u2le();
$self->{resource_idx} = $self->{_io}->read_u2le();
}
sub resource {
my ($self) = @_;
return $self->{resource} if ($self->{resource});
$self->{resource} = @{$self->_parent()->resources()}[$self->resource_idx()];
return $self->{resource};
}
sub id {
my ($self) = @_;
return $self->{id};
}
sub resource_idx {
my ($self) = @_;
return $self->{resource_idx};
}
1;