### Home Classes Methods

### In Files

- lib/ffi/library.rb

### Methods

- ::extended
- #attach_function
- #attach_variable
- #callback
- #enum
- #enum_type
- #enum_value
- #ffi_convention
- #ffi_lib
- #ffi_lib_flags
- #ffi_libraries
- #find_type
- #function_names
- #typedef

### Files

- History.txt
- README.rdoc

### Class/Module Index

Quicksearch

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- FFI::Enum
- FFI::Enums
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# FFI::Library

This module is the base to use native functions.

A basic usage may be:

    require 'ffi'

    module Hello
      extend FFI::Library
      ffi_lib FFI::Library::LIBC
      attach_function 'puts', [ :string ], :int
    end

    Hello.puts("Hello, World")

### Constants

CURRENT_PROCESS
FlagsMap

  Flags used in {ffi_lib}.

  This map allows you to supply symbols to {ffi_lib_flags} instead of the actual constants.

LIBC

### Public Class Methods

extended(mod) click to toggle source

@param mod extended object @return [nil] @raise {RuntimeError} if `mod` is not a Module Test if extended object is a Module. If not, raise RuntimeError.

    # File lib/ffi/library.rb, line 77
    def self.extended(mod)
      raise RuntimeError.new("must only be extended by module") unless mod.kind_of?(Module)
    end

### Public Instance Methods

attach_function(name, func, args, returns = nil, options = nil) click to toggle source

@overload attach_function(func, args, returns, options = {})

    @example attach function without an explicit name
      module Foo
        extend FFI::Library
        ffi_lib FFI::Library::LIBC
        attach_function :malloc, [:size_t], :pointer
      end
      # now callable via Foo.malloc

@overload attach_function(name, func, args, returns, options = {})

    @example attach function with an explicit name
      module Bar
        extend FFI::Library
        ffi_lib FFI::Library::LIBC
        attach_function :c_malloc, :malloc, [:size_t], :pointer
      end
      # now callable via Bar.c_malloc

Attach C function `func` to this module.

@param [to_s] name name of ruby method to attach as @param [to_s] func name of C function to attach @param [Array<Symbol>] args an array of types @param [Symbol] returns type of return value @option options [Boolean] :blocking (@blocking) set to true if the C function is a blocking call @option options [Symbol] :convention (:default) calling convention (see {ffi_convention}) @option options [FFI::Enums] :enums @option options [Hash] :type_map

@return [FFI::VariadicInvoker]

@raise [FFI::NotFoundError] if `func` cannot be found in the attached libraries (see {ffi_lib})

    # File lib/ffi/library.rb, line 210
    def attach_function(name, func, args, returns = nil, options = nil)
      mname, a2, a3, a4, a5 = name, func, args, returns, options
      cname, arg_types, ret_type, opts = (a4 && (a2.is_a?(String) || a2.is_a?(Symbol))) ? [ a2, a3, a4, a5 ] : [ mname.to_s, a2, a3, a4 ]

      # Convert :foo to the native type
      arg_types.map! { |e| find_type(e) }
      options = {
        :convention => ffi_convention,
        :type_map => defined?(@ffi_typedefs) ? @ffi_typedefs : nil,
        :blocking => defined?(@blocking) && @blocking,
        :enums => defined?(@ffi_enums) ? @ffi_enums : nil,
      }

      @blocking = false
      options.merge!(opts) if opts && opts.is_a?(Hash)

      # Try to locate the function in any of the libraries
      invokers = []
      ffi_libraries.each do |lib|
        if invokers.empty?
          begin
            function = nil
            function_names(cname, arg_types).find do |fname|
              function = lib.find_function(fname)
            end
            raise LoadError unless function

            invokers << if arg_types.length > 0 && arg_types[arg_types.length - 1] == FFI::NativeType::VARARGS
              VariadicInvoker.new(function, arg_types, find_type(ret_type), options)

            else
              Function.new(find_type(ret_type), arg_types, function, options)
            end

          rescue LoadError
          end
        end
      end
      invoker = invokers.compact.shift
      raise FFI::NotFoundError.new(cname.to_s, ffi_libraries.map { |lib| lib.name }) unless invoker

      invoker.attach(self, mname.to_s)
      invoker
    end

attach_variable(mname, a1, a2 = nil) click to toggle source

@overload attach_variable(mname, cname, type)

    @example
     module Bar
       extend FFI::Library
       ffi_lib 'my_lib'
       attach_variable :c_myvar, :myvar, :long
     end
     # now callable via Bar.c_myvar

@overload attach_variable(cname, type)

    @example
     module Bar
       extend FFI::Library
       ffi_lib 'my_lib'
       attach_variable :myvar, :long
     end
     # now callable via Bar.myvar

@param [to_s] mname name of ruby method to attach as @param [to_s] cname name of C variable to attach @param [DataConverter, Struct, Symbol, Type] type C varaible's type @return [DynamicLibrary::Symbol] @raise {FFI::NotFoundError} if `cname` cannot be found in libraries

Attach C variable `cname` to this module.

    # File lib/ffi/library.rb, line 305
    def attach_variable(mname, a1, a2 = nil)
      cname, type = a2 ? [ a1, a2 ] : [ mname.to_s, a1 ]
      address = nil
      ffi_libraries.each do |lib|
        begin
          address = lib.find_variable(cname.to_s)
          break unless address.nil?
        rescue LoadError
        end
      end

      raise FFI::NotFoundError.new(cname, ffi_libraries) if address.nil? || address.null?
      if type.is_a?(Class) && type < FFI::Struct
        # If it is a global struct, just attach directly to the pointer
        s = type.new(address)
        self.module_eval           @@ffi_gvar_#{mname} = s          def self.#{mname}            @@ffi_gvar_#{mname}          end, __FILE__, __LINE__

      else
        sc = Class.new(FFI::Struct)
        sc.layout :gvar, find_type(type)
        s = sc.new(address)
        #
        # Attach to this module as mname/mname=
        #
        self.module_eval           @@ffi_gvar_#{mname} = s          def self.#{mname}            @@ffi_gvar_#{mname}[:gvar]          end          def self.#{mname}=(value)            @@ffi_gvar_#{mname}[:gvar] = value          end, __FILE__, __LINE__

      end

      address
    end

callback(*args) click to toggle source

@overload callback(name, params, ret) @overload callback(params, ret) @param name callback name to add to type map @param [Array] params array of parameters' types @param [DataConverter, Struct, Symbol, Type] ret callback return type @return [FFI::CallbackInfo]

    # File lib/ffi/library.rb, line 356
    def callback(*args)
      raise ArgumentError, "wrong number of arguments" if args.length < 2 || args.length > 3
      name, params, ret = if args.length == 3
        args
      else
        [ nil, args[0], args[1] ]
      end

      options = Hash.new
      options[:convention] = ffi_convention
      options[:enums] = @ffi_enums if defined?(@ffi_enums)
      cb = FFI::CallbackInfo.new(find_type(ret), params.map { |e| find_type(e) }, options)

      # Add to the symbol -> type map (unless there was no name)
      unless name.nil?
        typedef cb, name
      end

      cb
    end

enum(*args) click to toggle source

@overload enum(name, values)

    Create a named enum.
    @example
     enum :foo, [:zero, :one, :two]  # named enum
    @param [Symbol] name name for new enum
    @param [Array] values values for enum

@overload enum(*args)

    Create an unnamed enum.
    @example
     enum :zero, :one, :two  # unnamed enum
    @param args values for enum

@overload enum(values)

    Create an unnamed enum.
    @example
     enum [:zero, :one, :two]  # unnamed enum, equivalent to above example
    @param [Array] values values for enum

@return [FFI::Enum] Create a new {FFI::Enum}.

    # File lib/ffi/library.rb, line 435
    def enum(*args)
      name, values = if args[0].kind_of?(Symbol) && args[1].kind_of?(Array)
        [ args[0], args[1] ]
      elsif args[0].kind_of?(Array)
        [ nil, args[0] ]
      else
        [ nil, args ]
      end
      @ffi_enums = FFI::Enums.new unless defined?(@ffi_enums)
      @ffi_enums << (e = FFI::Enum.new(values, name))

      # If called as enum :foo, [ :zero, :one, :two ], add a typedef alias
      typedef(e, name) if name
      e
    end

enum_type(name) click to toggle source

@param name @return [FFI::Enum] Find an enum by name.

    # File lib/ffi/library.rb, line 454
    def enum_type(name)
      @ffi_enums.find(name) if defined?(@ffi_enums)
    end

enum_value(symbol) click to toggle source

@param symbol @return [FFI::Enum] Find an enum by a symbol it contains.

    # File lib/ffi/library.rb, line 461
    def enum_value(symbol)
      @ffi_enums.__map_symbol(symbol)
    end

ffi_convention(convention = nil) click to toggle source

Set the calling convention for {attach_function} and {callback}

@see en.wikipedia.org/wiki/Stdcall#stdcall @note `:stdcall` is typically used for attaching Windows API functions

@param [Symbol] convention one of `:default`, `:stdcall` @return [Symbol] the new calling convention

    # File lib/ffi/library.rb, line 139
    def ffi_convention(convention = nil)
      @ffi_convention ||= :default
      @ffi_convention = convention if convention
      @ffi_convention
    end

ffi_lib(*names) click to toggle source

@param [Array] names names of libraries to load @return [Array<DynamicLibrary>] @raise {LoadError} if a library cannot be opened Load native libraries.

    # File lib/ffi/library.rb, line 86
    def ffi_lib(*names)
      lib_flags = defined?(@ffi_lib_flags) ? @ffi_lib_flags : FFI::DynamicLibrary::RTLD_LAZY | FFI::DynamicLibrary::RTLD_LOCAL
      ffi_libs = names.map do |name|

        if name == FFI::CURRENT_PROCESS
          FFI::DynamicLibrary.open(nil, FFI::DynamicLibrary::RTLD_LAZY | FFI::DynamicLibrary::RTLD_LOCAL)

        else
          libnames = (name.is_a?(::Array) ? name : [ name ]).map { |n| [ n, FFI.map_library_name(n) ].uniq }.flatten.compact
          lib = nil
          errors = {}

          libnames.each do |libname|
            begin
              lib = FFI::DynamicLibrary.open(libname, lib_flags)
              break if lib

            rescue Exception => ex
              ldscript = false
              if ex.message =~ /(([^ \t()])+\.so([^ \t:()])*):([ \t])*invalid ELF header/
                if File.read($1) =~ /GROUP *\( *([^ \)]+) *\)/
                  libname = $1
                  ldscript = true
                end
              end

              if ldscript
                retry
              else
                errors[libname] = ex
              end
            end
          end

          if lib.nil?
            raise LoadError.new(errors.values.join(".\n"))
          end

          # return the found lib
          lib
        end
      end

      @ffi_libs = ffi_libs
    end

ffi_lib_flags(*flags) click to toggle source

Sets library flags for {ffi_lib}.

@example

    ffi_lib_flags(:lazy, :local) # => 5

@param [Symbol, …] flags (see {FlagsMap}) @return [Fixnum] the new value

    # File lib/ffi/library.rb, line 172
    def ffi_lib_flags(*flags)
      @ffi_lib_flags = flags.inject(0) { |result, f| result | FlagsMap[f] }
    end

ffi_libraries() click to toggle source

@see ffi_lib @return [Array<FFI::DynamicLibrary>] array of currently loaded FFI libraries @raise [LoadError] if no libraries have been loaded (using {ffi_lib}) Get FFI libraries loaded using {ffi_lib}.

    # File lib/ffi/library.rb, line 149
    def ffi_libraries
      raise LoadError.new("no library specified") if !defined?(@ffi_libs) || @ffi_libs.empty?
      @ffi_libs
    end

find_type(t) click to toggle source

@param [DataConverter, Type, Struct, Symbol] t type to find @return [Type] Find a type definition.

    # File lib/ffi/library.rb, line 468
    def find_type(t)
      if t.kind_of?(Type)
        t

      elsif defined?(@ffi_typedefs) && @ffi_typedefs.has_key?(t)
        @ffi_typedefs[t]

      elsif t.is_a?(Class) && t < Struct
        Type::POINTER

      elsif t.is_a?(DataConverter)
        # Add a typedef so next time the converter is used, it hits the cache
        typedef Type::Mapped.new(t), t

      end || FFI.find_type(t)
    end

function_names(name, arg_types) click to toggle source

@param [to_s] name function name @param [Array] arg_types function's argument types @return [Array<String>] This function returns a list of possible names to lookup. @note Function names on windows may be decorated if they are using stdcall. See

    * http://en.wikipedia.org/wiki/Name_mangling#C_name_decoration_in_Microsoft_Windows
    * http://msdn.microsoft.com/en-us/library/zxk0tw93%28v=VS.100%29.aspx
    * http://en.wikibooks.org/wiki/X86_Disassembly/Calling_Conventions#STDCALL
    Note that decorated names can be overridden via def files.  Also note that the
    windows api, although using, doesn't have decorated names.

    # File lib/ffi/library.rb, line 265
    def function_names(name, arg_types)
      result = [name.to_s]
      if ffi_convention == :stdcall
        # Get the size of each parameter
        size = arg_types.inject(0) do |mem, arg|
          mem + arg.size
        end

        # Next, the size must be a multiple of 4
        size += (4 - size) % 4

        result << "_#{name.to_s}@#{size}" # win32
        result << "#{name.to_s}@#{size}" # win64
      end
      result
    end

typedef(old, add, info=nil) click to toggle source

@param [DataConverter, Symbol, Type] old @param add @param [] info @return [FFI::Enum, FFI::Type] Register or get an already registered type definition.

To register a new type definition, `old` should be a {FFI::Type}. `add` is in this case the type definition.

If `old` is a {DataConverter}, a {Type::Mapped} is returned.

If `old` is `:enum`

- and `add` is an `Array`, a call to {enum} is made with `add` as single parameter;

- in others cases, `info` is used to create a named enum.

If `old` is a key for type map, typedef get `old` type definition.

    # File lib/ffi/library.rb, line 393
    def typedef(old, add, info=nil)
      @ffi_typedefs = Hash.new unless defined?(@ffi_typedefs)

      @ffi_typedefs[add] = if old.kind_of?(FFI::Type)
        old

      elsif @ffi_typedefs.has_key?(old)
        @ffi_typedefs[old]

      elsif old.is_a?(DataConverter)
        FFI::Type::Mapped.new(old)

      elsif old == :enum
        if add.kind_of?(Array)
          self.enum(add)
        else
          self.enum(info, add)
        end

      else
        FFI.find_type(old)
      end
    end

[Validate]

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