This page hosts a formal specification of Android nanoapp header using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for Ruby generated by Kaitai Struct depends on the Ruby runtime library. You have to install it before you can parse data.
The Ruby runtime library can be installed from RubyGems:
gem install kaitai-structParse a local file and get structure in memory:
data = AndroidNanoappHeader.from_file("path/to/local/file.napp_header")
Or parse structure from a string of bytes:
bytes = "\x00\x01\x02..."
data = AndroidNanoappHeader.new(Kaitai::Struct::Stream.new(bytes))
After that, one can get various attributes from the structure by invoking getter methods like:
data.header_version # => get header version
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
require 'kaitai/struct/struct'
unless Gem::Version.new(Kaitai::Struct::VERSION) >= Gem::Version.new('0.9')
raise "Incompatible Kaitai Struct Ruby API: 0.9 or later is required, but you have #{Kaitai::Struct::VERSION}"
end
##
# @see https://android.googlesource.com/platform/system/chre/+/a7ff61b9/build/build_template.mk#130 Source
class AndroidNanoappHeader < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@header_version = @_io.read_u4le
raise Kaitai::Struct::ValidationNotEqualError.new(1, header_version, _io, "/seq/0") if not header_version == 1
@magic = @_io.read_bytes(4)
raise Kaitai::Struct::ValidationNotEqualError.new([78, 65, 78, 79].pack('C*'), magic, _io, "/seq/1") if not magic == [78, 65, 78, 79].pack('C*')
@app_id = @_io.read_u8le
@app_version = @_io.read_u4le
@flags = @_io.read_u4le
@hub_type = @_io.read_u8le
@chre_api_major_version = @_io.read_u1
@chre_api_minor_version = @_io.read_u1
@reserved = @_io.read_bytes(6)
raise Kaitai::Struct::ValidationNotEqualError.new([0, 0, 0, 0, 0, 0].pack('C*'), reserved, _io, "/seq/8") if not reserved == [0, 0, 0, 0, 0, 0].pack('C*')
self
end
def is_signed
return @is_signed unless @is_signed.nil?
@is_signed = (flags & 1) != 0
@is_signed
end
def is_encrypted
return @is_encrypted unless @is_encrypted.nil?
@is_encrypted = (flags & 2) != 0
@is_encrypted
end
def is_tcm_capable
return @is_tcm_capable unless @is_tcm_capable.nil?
@is_tcm_capable = (flags & 4) != 0
@is_tcm_capable
end
attr_reader :header_version
attr_reader :magic
attr_reader :app_id
attr_reader :app_version
attr_reader :flags
attr_reader :hub_type
attr_reader :chre_api_major_version
attr_reader :chre_api_minor_version
attr_reader :reserved
end