Class: Fiddle::Function

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

Overview

Description

A representation of a C function

Examples

'strcpy'

@libc = DL.dlopen "/lib/libc.so.6"
=> #<DL::Handle:0x00000001d7a8d8>
f = Fiddle::Function.new(@libc['strcpy'], [TYPE_VOIDP, TYPE_VOIDP], TYPE_VOIDP)
=> #<Fiddle::Function:0x00000001d8ee00>
buff = "000"
=> "000"
str = f.call(buff, "123")
=> #<DL::CPtr:0x00000001d0c380 ptr=0x000000018a21b8 size=0 free=0x00000000000000>
str.to_s
=> "123"

ABI check

@libc = DL.dlopen "/lib/libc.so.6"
=> #<DL::Handle:0x00000001d7a8d8>
f = Fiddle::Function.new(@libc['strcpy'], [TYPE_VOIDP, TYPE_VOIDP], TYPE_VOIDP)
=> #<Fiddle::Function:0x00000001d8ee00>
f.abi == Fiddle::Function::DEFAULT
=> true

Constant Summary collapse

DEFAULT =

Default ABI

INT2NUM(FFI_DEFAULT_ABI)
STDCALL =

FFI implementation of WIN32 stdcall convention

INT2NUM(FFI_STDCALL)

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#new(ptr, *args, ret_type, abi = DEFAULT) ⇒ Object

Constructs a Function object.

  • ptr is a referenced function, of a DL::Handle

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

  • ret_type is the return type of the function

  • abi is the ABI of the function



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# File 'function.c', line 41

static VALUE
initialize(int argc, VALUE argv[], VALUE self)
{
    ffi_cif * cif;
    ffi_type **arg_types;
    ffi_status result;
    VALUE ptr, args, ret_type, abi;
    int i;

    rb_scan_args(argc, argv, "31", &ptr, &args, &ret_type, &abi);
    if(NIL_P(abi)) abi = INT2NUM(FFI_DEFAULT_ABI);

    Check_Type(args, T_ARRAY);

    rb_iv_set(self, "@ptr", ptr);
    rb_iv_set(self, "@args", args);
    rb_iv_set(self, "@return_type", ret_type);
    rb_iv_set(self, "@abi", abi);

    TypedData_Get_Struct(self, ffi_cif, &function_data_type, cif);

    arg_types = xcalloc(RARRAY_LEN(args) + 1, sizeof(ffi_type *));

    for (i = 0; i < RARRAY_LEN(args); i++) {
	int type = NUM2INT(RARRAY_PTR(args)[i]);
	arg_types[i] = INT2FFI_TYPE(type);
    }
    arg_types[RARRAY_LEN(args)] = NULL;

    result = ffi_prep_cif (
	    cif,
	    NUM2INT(abi),
	    RARRAY_LENINT(args),
	    INT2FFI_TYPE(NUM2INT(ret_type)),
	    arg_types);

    if (result)
	rb_raise(rb_eRuntimeError, "error creating CIF %d", result);

    return self;
}

Instance Attribute Details

#abi ⇒ Object (readonly)

The ABI of the Function.



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# File 'lib/fiddle/function.rb', line 4

def abi
  @abi
end

Instance Method Details

#call ⇒ Object

Calls the constructed Function, with args

For an example see Fiddle::Function



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# File 'function.c', line 83

static VALUE
function_call(int argc, VALUE argv[], VALUE self)
{
    ffi_cif * cif;
    fiddle_generic retval;
    fiddle_generic *generic_args;
    void **values;
    VALUE cfunc, types, cPointer;
    int i;

    cfunc    = rb_iv_get(self, "@ptr");
    types    = rb_iv_get(self, "@args");
    cPointer = rb_const_get(mFiddle, rb_intern("Pointer"));

    if(argc != RARRAY_LENINT(types)) {
	rb_raise(rb_eArgError, "wrong number of arguments (%d for %d)",
		argc, RARRAY_LENINT(types));
    }

    TypedData_Get_Struct(self, ffi_cif, &function_data_type, cif);

    values = xcalloc((size_t)argc + 1, (size_t)sizeof(void *));
    generic_args = xcalloc((size_t)argc, (size_t)sizeof(fiddle_generic));

    for (i = 0; i < argc; i++) {
	VALUE type = RARRAY_PTR(types)[i];
	VALUE src = argv[i];

	if(NUM2INT(type) == TYPE_VOIDP) {
	    if(NIL_P(src)) {
		src = INT2NUM(0);
	    } else if(cPointer != CLASS_OF(src)) {
	        src = rb_funcall(cPointer, rb_intern("[]"), 1, src);
	    }
	    src = rb_Integer(src);
	}

	VALUE2GENERIC(NUM2INT(type), src, &generic_args[i]);
	values[i] = (void *)&generic_args[i];
    }
    values[argc] = NULL;

    ffi_call(cif, NUM2PTR(rb_Integer(cfunc)), &retval, values);

    rb_funcall(mFiddle, rb_intern("last_error="), 1, INT2NUM(errno));
#if defined(_WIN32)
    rb_funcall(mFiddle, rb_intern("win32_last_error="), 1, INT2NUM(errno));
#endif

    xfree(values);
    xfree(generic_args);

    return GENERIC2VALUE(rb_iv_get(self, "@return_type"), retval);
}