Class: Fiddle::Closure

Inherits:
Object
  • Object
show all
Defined in:
closure.c,
lib/fiddle/closure.rb,
closure.c

Overview

Description

An FFI closure wrapper, for handling callbacks.

Example

closure = Class.new(Fiddle::Closure) {
  def call
    10
  end
}.new(Fiddle::TYPE_INT, [])
  #=> #<#<Class:0x0000000150d308>:0x0000000150d240>
func = Fiddle::Function.new(closure, [], Fiddle::TYPE_INT)
  #=> #<Fiddle::Function:0x00000001516e58>
func.call
  #=> 10

Direct Known Subclasses

BlockCaller

Defined Under Namespace

Classes: BlockCaller

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(argv[], self) ⇒ Object

call-seq: new(ret, args, abi = Fiddle::DEFAULT)

Construct a new Closure object.

  • ret is the C type to be returned

  • args is an Array of arguments, passed to the callback function

  • abi is the abi of the closure

If there is an error in preparing the ffi_cif or ffi_prep_closure, then a RuntimeError will be raised.



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# File 'closure.c', line 189

static VALUE
initialize(int rbargc, VALUE argv[], VALUE self)
{
    VALUE ret;
    VALUE args;
    VALUE abi;
    fiddle_closure * cl;
    ffi_cif * cif;
    ffi_closure *pcl;
    ffi_status result;
    int i, argc;

    if (2 == rb_scan_args(rbargc, argv, "21", &ret, &args, &abi))
	abi = INT2NUM(FFI_DEFAULT_ABI);

    Check_Type(args, T_ARRAY);

    argc = RARRAY_LENINT(args);

    TypedData_Get_Struct(self, fiddle_closure, &closure_data_type, cl);

    cl->argv = (ffi_type **)xcalloc(argc + 1, sizeof(ffi_type *));

    for (i = 0; i < argc; i++) {
        int type = NUM2INT(RARRAY_PTR(args)[i]);
        cl->argv[i] = INT2FFI_TYPE(type);
    }
    cl->argv[argc] = NULL;

    rb_iv_set(self, "@ctype", ret);
    rb_iv_set(self, "@args", args);

    cif = &cl->cif;
    pcl = cl->pcl;

    result = ffi_prep_cif(cif, NUM2INT(abi), argc,
                INT2FFI_TYPE(NUM2INT(ret)),
		cl->argv);

    if (FFI_OK != result)
	rb_raise(rb_eRuntimeError, "error prepping CIF %d", result);

#if USE_FFI_CLOSURE_ALLOC
    result = ffi_prep_closure_loc(pcl, cif, callback,
		(void *)self, cl->code);
#else
    result = ffi_prep_closure(pcl, cif, callback, (void *)self);
    cl->code = (void *)pcl;
    i = mprotect(pcl, sizeof(*pcl), PROT_READ | PROT_EXEC);
    if (i) {
	rb_sys_fail("mprotect");
    }
#endif

    if (FFI_OK != result)
	rb_raise(rb_eRuntimeError, "error prepping closure %d", result);

    return self;
}

Instance Attribute Details

#args ⇒ Object (readonly)

arguments of the FFI closure



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# File 'lib/fiddle/closure.rb', line 8

def args
  @args
end

#ctype ⇒ Object (readonly)

the C type of the return of the FFI closure



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# File 'lib/fiddle/closure.rb', line 5

def ctype
  @ctype
end

Instance Method Details

#to_i ⇒ Object

Returns the memory address for this closure



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# File 'closure.c', line 249

static VALUE
to_i(VALUE self)
{
    fiddle_closure * cl;
    void *code;

    TypedData_Get_Struct(self, fiddle_closure, &closure_data_type, cl);

    code = cl->code;

    return PTR2NUM(code);
}