Fiddle::Closure

Class

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

Attributes

ctype

Read

the C type of the return of the FFI closure

args

Read

arguments of the FFI closure

Class Methods

new(ret, args, abi = Fiddle::DEFAULT)

ext/fiddle/closure.c View on GitHub

          
            static VALUE
initialize(int rbargc, VALUE argv[], VALUE self)
{
    VALUE ret;
    VALUE args;
    VALUE normalized_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 *));

    normalized_args = rb_ary_new_capa(argc);
    for (i = 0; i < argc; i++) {
        VALUE arg = rb_fiddle_type_ensure(RARRAY_AREF(args, i));
        rb_ary_push(normalized_args, arg);
        cl->argv[i] = rb_fiddle_int_to_ffi_type(NUM2INT(arg));
    }
    cl->argv[argc] = NULL;

    ret = rb_fiddle_type_ensure(ret);
    rb_iv_set(self, "@ctype", ret);
    rb_iv_set(self, "@args", normalized_args);

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

    result = ffi_prep_cif(cif,
                          NUM2INT(abi),
                          argc,
                          rb_fiddle_int_to_ffi_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;
}

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.

Instance Methods

to_i

ext/fiddle/closure.c View on GitHub

          
            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);
}

Returns the memory address for this closure