CStructParser

Parse C structs into usable Ruby objects like BinData records.

Installation

Install the gem and add to the application's Gemfile by executing:

bundle add CStructParser

If bundler is not being used to manage dependencies, install the gem by executing:

gem install CStructParser

Usage

For usage with FFI

require 'cstruct_parser'

sourceCode = %{
  #include <stdint.h>

  #define EI_NIDENT (16)

  typedef uint64_t Elf64_Addr;
  typedef uint16_t Elf64_Half;
  typedef uint32_t Elf64_Word;

  typedef struct
  {
    unsigned char e_ident[EI_NIDENT];
    Elf64_Half e_type;
    Elf64_Half e_machine;
    Elf64_Word e_version;
    Elf64_Addr e_entry;
  } Elf64_Ehdr;
}

# Note that you can specify path to C header file instead of passing string
CStructParser.to_ffi(sourceCode)
# class Elf64Ehdr < FFI::Struct
#   layout :e_ident, [:uchar, 16],
#          :e_type, :ushort,
#          :e_machine, :ushort,
#          :e_version, :uint,
#          :e_entry, :ulong
# end

For usage with BinData

records = CStructParser.to_bindata('stuff.h')
# class Elf64Ehdr < BinData::Record
#  endian :little
#  array :e_ident, type: :uint8, initial_length: 16
#  uint16 :e_type
#  uint16 :e_machine
#  uint32 :e_version
#  uint64 :e_entry
#end
require 'bindata'
# Currently we get it as string so need to require/eval but it would be better to implement that objects are directly created
eval(records)
Elf64Ehdr.read(File.open('/bin/ruby'))
# => {e_ident: [127, 69, 76, 70, 2, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0], e_type: 3, e_machine: 62, e_version: 1, e_entry: 4272}

Other use cases

Not implemented, but should be quite simple to add support for other uses like BinaryStruct, String#unpack format etc.

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/davispuh/CStructParser.