bsdcapsicum.rb/lib/bsd/capsicum/ffi.rb

# frozen_string_literal: true

module BSD::Capsicum
  module FFI
    require "fiddle"
    require "fiddle/import"
    include Fiddle::Types
    include Constants
    extend Fiddle::Importer
    dlload Dir["/lib/libc.*"].first

    extern "int cap_getmode(u_int*)"
    extern "int cap_enter(void)"
    extern "int cap_rights_limit(int, const cap_rights_t*)"
    extern "cap_rights_t* __cap_rights_init(int version, cap_rights_t*, ...)"

    module_function

    ##
    # Provides a Ruby interface for cap_enter(2)
    # @return [Integer]
    def cap_enter
      self["cap_enter"].call
    end

    ##
    # Provides a Ruby interface for cap_getmode(2)
    # @param [Fiddle::Pointer] uintp
    # @return [Integer]
    def cap_getmode(uintp)
      self["cap_getmode"].call(uintp)
    end

    ##
    # Provides a Ruby interface for cap_rights_limit(2)
    # @param [Integer] fd
    # @param [Fiddle::Pointer] rightsp
    # @return [Integer]
    def cap_rights_limit(fd, rightsp)
      self["cap_rights_limit"].call(fd, rightsp)
    end

    ##
    # Provides a Ruby interface for cap_rights_init(2)
    # @see BSD::Capsicum::Constants See Constants for a full list of capabilities
    # @param [Fiddle::Pointer] rightsp
    #  A pointer to initialize the `cap_rights_t` structure
    # @param [Array<Symbol, Integer>] capabilities
    #  An allowed set of capabilities
    # @return [Fiddle::Pointer]
    #  Returns a pointer to the structure `cap_rights_t`
    def cap_rights_init(rightsp, *capabilities)
      self["__cap_rights_init"].call(
        CAP_RIGHTS_VERSION,
        rightsp,
        *capabilities.flat_map { |cap|
          [ULONG_LONG, cap_all.include?(cap) ? Constants.const_get(cap) : cap]
        }
      )
    end

    ##
    # @api private
    # @return [Array<Symbol>]
    #  Returns all known capabilities
    def cap_all
      @cap_all ||= Constants.constants.select { _1.to_s.start_with?("CAP_") }
    end
  end
  private_constant :FFI
end