com.android.opengl.shaders_cache file: Ruby parsing library

Android apps using directly or indirectly OpenGL cache compiled shaders into com.android.opengl.shaders_cache file.

Application

Android

KS implementation details

License: Apache-2.0

This page hosts a formal specification of com.android.opengl.shaders_cache file using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Runtime 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-struct

Code

Parse a local file and get structure in memory:

data = AndroidOpenglShadersCache.from_file("path/to/local/file.com.android.opengl.shaders_cache file")

Or parse structure from a string of bytes:

bytes = "\x00\x01\x02..."
data = AndroidOpenglShadersCache.new(Kaitai::Struct::Stream.new(bytes))

After that, one can get various attributes from the structure by invoking getter methods like:

data.crc32 # => crc32 of `contents`

Ruby source code to parse com.android.opengl.shaders_cache file

android_opengl_shaders_cache.rb

# 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


##
# Android apps using directly or indirectly OpenGL cache compiled shaders
# into com.android.opengl.shaders_cache file.
# @see https://android.googlesource.com/platform/frameworks/native/+/master/opengl/libs/EGL/FileBlobCache.cpp Source
class AndroidOpenglShadersCache < Kaitai::Struct::Struct
  def initialize(_io, _parent = nil, _root = self)
    super(_io, _parent, _root)
    _read
  end

  def _read
    @magic = @_io.read_bytes(4)
    raise Kaitai::Struct::ValidationNotEqualError.new([69, 71, 76, 36].pack('C*'), magic, _io, "/seq/0") if not magic == [69, 71, 76, 36].pack('C*')
    @crc32 = @_io.read_u4le
    @_raw_contents = @_io.read_bytes_full
    _io__raw_contents = Kaitai::Struct::Stream.new(@_raw_contents)
    @contents = Cache.new(_io__raw_contents, self, @_root)
    self
  end
  class Alignment < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @alignment = @_io.read_bytes(((_io.pos + 3) & (~3 - _io.pos)))
      self
    end

    ##
    # garbage from memory
    attr_reader :alignment
  end
  class PrefixedString < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @len_str = @_io.read_u4le
      @str = (Kaitai::Struct::Stream::bytes_terminate(@_io.read_bytes(len_str), 0, false)).force_encoding("ascii")
      @alignment = Alignment.new(@_io, self, @_root)
      self
    end
    attr_reader :len_str
    attr_reader :str
    attr_reader :alignment
  end

  ##
  # @see https://android.googlesource.com/platform/frameworks/native/+/master/opengl/libs/EGL/BlobCache.cpp Source
  class Cache < Kaitai::Struct::Struct
    def initialize(_io, _parent = nil, _root = self)
      super(_io, _parent, _root)
      _read
    end

    def _read
      @magic = @_io.read_bytes(4)
      raise Kaitai::Struct::ValidationNotEqualError.new([36, 98, 66, 95].pack('C*'), magic, _io, "/types/cache/seq/0") if not magic == [36, 98, 66, 95].pack('C*')
      @version = @_io.read_u4le
      @device_version = @_io.read_u4le
      @num_entries = @_io.read_u4le
      if version >= 3
        @build_id = PrefixedString.new(@_io, self, @_root)
      end
      @entries = Array.new(num_entries)
      (num_entries).times { |i|
        @entries[i] = Entry.new(@_io, self, @_root)
      }
      self
    end
    class Entry < Kaitai::Struct::Struct
      def initialize(_io, _parent = nil, _root = self)
        super(_io, _parent, _root)
        _read
      end

      def _read
        @len_key = @_io.read_u4le
        @len_value = @_io.read_u4le
        @key = @_io.read_bytes(len_key)
        @value = @_io.read_bytes(len_value)
        @alignment = Alignment.new(@_io, self, @_root)
        self
      end
      attr_reader :len_key
      attr_reader :len_value
      attr_reader :key
      attr_reader :value
      attr_reader :alignment
    end
    attr_reader :magic
    attr_reader :version
    attr_reader :device_version
    attr_reader :num_entries
    attr_reader :build_id
    attr_reader :entries
  end
  attr_reader :magic

  ##
  # crc32 of `contents`
  attr_reader :crc32
  attr_reader :contents
  attr_reader :_raw_contents
end