Class: Fiddle::Function

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

Overview

Description

A representation of a C function

Examples

‘strcpy’

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

ABI check

@libc = Fiddle.dlopen "/lib/libc.so.6"
  #=> #<Fiddle::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) ⇒ Object #args ⇒ Object #ret_type ⇒ Object #abi=(DEFAULT) ⇒ Object #name ⇒ Object #need_gvl ⇒ Object

Constructs a Function object.

  • ptr is a referenced function, of a Fiddle::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

  • name is the name of the function

  • need_gvl is whether GVL is needed to call the function



121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
 
# File 'function.c', line 121

static VALUE
initialize(int argc, VALUE argv[], VALUE self)
{
    ffi_cif * cif;
    VALUE ptr, arg_types, ret_type, abi, kwargs;
    VALUE name = Qnil;
    VALUE need_gvl = Qfalse;
    int c_ret_type;
    bool is_variadic = false;
    ffi_abi c_ffi_abi;
    void *cfunc;

    rb_scan_args(argc, argv, "31:", &ptr, &arg_types, &ret_type, &abi, &kwargs);
    rb_iv_set(self, "@closure", ptr);

    if (!NIL_P(kwargs)) {
        enum {
            kw_name,
            kw_need_gvl,
            kw_max_,
        };
        static ID kw[kw_max_];
        VALUE args[kw_max_];
        if (!kw[0]) {
            kw[kw_name] = rb_intern_const("name");
            kw[kw_need_gvl] = rb_intern_const("need_gvl");
        }
        rb_get_kwargs(kwargs, kw, 0, kw_max_, args);
        if (args[kw_name] != Qundef) {
            name = args[kw_name];
        }
        if (args[kw_need_gvl] != Qundef) {
            need_gvl = args[kw_need_gvl];
        }
    }
    rb_iv_set(self, "@name", name);
    rb_iv_set(self, "@need_gvl", need_gvl);

    ptr = rb_Integer(ptr);
    cfunc = NUM2PTR(ptr);
    PTR2NUM(cfunc);
    c_ffi_abi = NIL_P(abi) ? FFI_DEFAULT_ABI : NUM2INT(abi);
    abi = INT2FIX(c_ffi_abi);
    ret_type = rb_fiddle_type_ensure(ret_type);
    c_ret_type = NUM2INT(ret_type);
    (void)INT2FFI_TYPE(c_ret_type); /* raise */
    ret_type = INT2FIX(c_ret_type);

    arg_types = normalize_argument_types("argument types",
                                         arg_types,
                                         &is_variadic);
#ifndef HAVE_FFI_PREP_CIF_VAR
    if (is_variadic) {
        rb_raise(rb_eNotImpError,
                 "ffi_prep_cif_var() is required in libffi "
                 "for variadic arguments");
    }
#endif

    rb_iv_set(self, "@ptr", ptr);
    rb_iv_set(self, "@argument_types", arg_types);
    rb_iv_set(self, "@return_type", ret_type);
    rb_iv_set(self, "@abi", abi);
    rb_iv_set(self, "@is_variadic", is_variadic ? Qtrue : Qfalse);

    TypedData_Get_Struct(self, ffi_cif, &function_data_type, cif);
    cif->arg_types = NULL;

    return self;
}

Instance Attribute Details

#abi ⇒ Object (readonly)

The ABI of the Function.



5
6
7
 
# File 'lib/fiddle/function.rb', line 5

def abi
  @abi
end

#name ⇒ Object (readonly)

The name of this function



11
12
13
 
# File 'lib/fiddle/function.rb', line 11

def name
  @name
end

#ptr ⇒ Object (readonly)

The address of this function



8
9
10
 
# File 'lib/fiddle/function.rb', line 8

def ptr
  @ptr
end

Instance Method Details

#call(argv[], self) ⇒ Object

Calls the constructed Function, with args. Caller must ensure the underlying function is called in a thread-safe manner if running in a multi-threaded process.

Note that it is not thread-safe to use this method to directly or indirectly call many Ruby C-extension APIs unless you don’t pass need_gvl: true to Fiddle::Function#new.

For an example see Fiddle::Function



209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
 
# File 'function.c', line 209

static VALUE
function_call(int argc, VALUE argv[], VALUE self)
{
    struct nogvl_ffi_call_args args = { 0 };
    fiddle_generic *generic_args;
    VALUE cfunc;
    VALUE abi;
    VALUE arg_types;
    VALUE cPointer;
    VALUE is_variadic;
    VALUE need_gvl;
    int n_arg_types;
    int n_fixed_args = 0;
    int n_call_args = 0;
    int i;
    int i_call;
    VALUE converted_args = Qnil;
    VALUE alloc_buffer = 0;

    cfunc    = rb_iv_get(self, "@ptr");
    abi      = rb_iv_get(self, "@abi");
    arg_types = rb_iv_get(self, "@argument_types");
    cPointer = rb_const_get(mFiddle, rb_intern("Pointer"));
    is_variadic = rb_iv_get(self, "@is_variadic");
    need_gvl = rb_iv_get(self, "@need_gvl");

    n_arg_types = RARRAY_LENINT(arg_types);
    n_fixed_args = n_arg_types;
    if (RTEST(is_variadic)) {
        if (argc < n_arg_types) {
            rb_error_arity(argc, n_arg_types, UNLIMITED_ARGUMENTS);
        }
        if (((argc - n_arg_types) % 2) != 0) {
            rb_raise(rb_eArgError,
                     "variadic arguments must be type and value pairs: "
                     "%"PRIsVALUE,
                     rb_ary_new_from_values(argc, argv));
        }
        n_call_args = n_arg_types + ((argc - n_arg_types) / 2);
    }
    else {
        if (argc != n_arg_types) {
            rb_error_arity(argc, n_arg_types, n_arg_types);
        }
        n_call_args = n_arg_types;
    }
    Check_Max_Args("the number of arguments", n_call_args);

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

    if (is_variadic && args.cif->arg_types) {
        xfree(args.cif->arg_types);
        args.cif->arg_types = NULL;
    }

    if (!args.cif->arg_types) {
        VALUE fixed_arg_types = arg_types;
        VALUE return_type;
        int c_return_type;
        ffi_type *ffi_return_type;
        ffi_type **ffi_arg_types;
        ffi_status result;

        arg_types = rb_ary_dup(fixed_arg_types);
        for (i = n_fixed_args; i < argc; i += 2) {
          VALUE arg_type = argv[i];
          int c_arg_type;
          arg_type = rb_fiddle_type_ensure(arg_type);
          c_arg_type = NUM2INT(arg_type);
          (void)INT2FFI_TYPE(c_arg_type); /* raise */
          rb_ary_push(arg_types, INT2FIX(c_arg_type));
        }

        return_type = rb_iv_get(self, "@return_type");
        c_return_type = FIX2INT(return_type);
        ffi_return_type = INT2FFI_TYPE(c_return_type);

        ffi_arg_types = xcalloc(n_call_args + 1, sizeof(ffi_type *));
        for (i_call = 0; i_call < n_call_args; i_call++) {
            VALUE arg_type;
            int c_arg_type;
            arg_type = RARRAY_AREF(arg_types, i_call);
            c_arg_type = FIX2INT(arg_type);
            ffi_arg_types[i_call] = INT2FFI_TYPE(c_arg_type);
        }
        ffi_arg_types[i_call] = NULL;

        if (is_variadic) {
#ifdef HAVE_FFI_PREP_CIF_VAR
            result = ffi_prep_cif_var(args.cif,
                                      FIX2INT(abi),
                                      n_fixed_args,
                                      n_call_args,
                                      ffi_return_type,
                                      ffi_arg_types);
#else
            /* This code is never used because ffi_prep_cif_var()
             * availability check is done in #initialize. */
            result = FFI_BAD_TYPEDEF;
#endif
        }
        else {
            result = ffi_prep_cif(args.cif,
                                  FIX2INT(abi),
                                  n_call_args,
                                  ffi_return_type,
                                  ffi_arg_types);
        }
        if (result != FFI_OK) {
            xfree(ffi_arg_types);
            args.cif->arg_types = NULL;
            rb_raise(rb_eRuntimeError, "error creating CIF %d", result);
        }
    }

    generic_args = ALLOCV(alloc_buffer,
                          sizeof(fiddle_generic) * n_call_args +
                          sizeof(void *) * (n_call_args + 1));
    args.values = (void **)((char *)generic_args +
                            sizeof(fiddle_generic) * n_call_args);

    for (i = 0, i_call = 0;
         i < argc && i_call < n_call_args;
         i++, i_call++) {
        VALUE arg_type;
        int c_arg_type;
        VALUE original_src;
        VALUE src;
        arg_type = RARRAY_AREF(arg_types, i_call);
        c_arg_type = FIX2INT(arg_type);
        if (i >= n_fixed_args) {
            i++;
        }
        src = argv[i];

        if (c_arg_type == TYPE_VOIDP) {
            if (NIL_P(src)) {
                src = INT2FIX(0);
            }
            else if (cPointer != CLASS_OF(src)) {
                src = rb_funcall(cPointer, rb_intern("[]"), 1, src);
                if (NIL_P(converted_args)) {
                    converted_args = rb_ary_new();
                }
                rb_ary_push(converted_args, src);
            }
            src = rb_Integer(src);
        }

        original_src = src;
        VALUE2GENERIC(c_arg_type, src, &generic_args[i_call]);
        if (src != original_src) {
            if (NIL_P(converted_args)) {
                converted_args = rb_ary_new();
            }
            rb_ary_push(converted_args, src);
        }
        args.values[i_call] = (void *)&generic_args[i_call];
    }
    args.values[i_call] = NULL;
    args.fn = (void(*)(void))NUM2PTR(cfunc);

    if (RTEST(need_gvl)) {
        ffi_call(args.cif, args.fn, &(args.retval), args.values);
    }
    else {
        (void)rb_thread_call_without_gvl(nogvl_ffi_call, &args, 0, 0);
    }

    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

    ALLOCV_END(alloc_buffer);

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

#need_gvl? ⇒ Boolean

Whether GVL is needed to call this function

Returns:

  • (Boolean) 


14
15
16
 
# File 'lib/fiddle/function.rb', line 14

def need_gvl?
  @need_gvl
end

#to_i ⇒ Object

The integer memory location of this function



19
20
21
 
# File 'lib/fiddle/function.rb', line 19

def to_i
  ptr.to_i
end