1 | //! Representations of C types and arrays thereof. |
2 | //! |
3 | //! These are used to describe the types of the arguments and results of |
4 | //! functions. When we construct a [CIF](super::Cif) (“Call |
5 | //! Inter<span></span>Face”), we provide a sequence of argument types |
6 | //! and a result type, and libffi uses this to figure out how to set up |
7 | //! a call to a function with those types. |
8 | |
9 | use libc; |
10 | use std::fmt; |
11 | use std::mem; |
12 | use std::ptr; |
13 | |
14 | use crate::low; |
15 | |
16 | use super::util::Unique; |
17 | |
18 | // Internally we represent types and type arrays using raw pointers, |
19 | // since this is what libffi understands. Below we wrap them with |
20 | // types that implement Drop and Clone. |
21 | |
22 | type Type_ = *mut low::ffi_type; |
23 | type TypeArray_ = *mut Type_; |
24 | |
25 | // Informal indication that the object should be considered owned by |
26 | // the given reference. |
27 | type Owned<T> = T; |
28 | |
29 | /// Represents a single C type. |
30 | /// |
31 | /// # Example |
32 | /// |
33 | /// Suppose we have a C struct: |
34 | /// |
35 | /// ```c |
36 | /// struct my_struct { |
37 | /// uint16_t f1; |
38 | /// uint64_t f2; |
39 | /// }; |
40 | /// ``` |
41 | /// |
42 | /// To pass the struct by value via libffi, we need to construct a |
43 | /// `Type` object describing its layout: |
44 | /// |
45 | /// ``` |
46 | /// use libffi::middle::Type; |
47 | /// |
48 | /// let my_struct = Type::structure(vec![ |
49 | /// Type::u64(), |
50 | /// Type::u16(), |
51 | /// ]); |
52 | /// ``` |
53 | pub struct Type(Unique<low::ffi_type>); |
54 | |
55 | /// Represents a sequence of C types. |
56 | /// |
57 | /// This can be used to construct a struct type or as the arguments |
58 | /// when creating a [`Cif`]. |
59 | pub struct TypeArray(Unique<*mut low::ffi_type>); |
60 | |
61 | impl fmt::Debug for Type { |
62 | fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { |
63 | formatter.write_fmt(format_args!("Type( {:?})" , *self.0)) |
64 | } |
65 | } |
66 | |
67 | impl fmt::Debug for TypeArray { |
68 | fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { |
69 | formatter.write_fmt(format_args!("TypeArray( {:?})" , *self.0)) |
70 | } |
71 | } |
72 | |
73 | /// Computes the length of a raw `TypeArray_` by searching for the |
74 | /// null terminator. |
75 | unsafe fn ffi_type_array_len(mut array: TypeArray_) -> usize { |
76 | let mut count: usize = 0; |
77 | while !(*array).is_null() { |
78 | count += 1; |
79 | array = array.offset(count:1); |
80 | } |
81 | count |
82 | } |
83 | |
84 | /// Creates an empty `TypeArray_` with null terminator. |
85 | unsafe fn ffi_type_array_create_empty(len: usize) -> Owned<TypeArray_> { |
86 | let array: *mut *mut ffi_type = libc::malloc((len + 1) * mem::size_of::<Type_>()) as TypeArray_; |
87 | assert!( |
88 | !array.is_null(), |
89 | "ffi_type_array_create_empty: out of memory" |
90 | ); |
91 | *array.add(count:len) = ptr::null_mut::<low::ffi_type>() as Type_; |
92 | array |
93 | } |
94 | |
95 | /// Creates a null-terminated array of Type_. Takes ownership of |
96 | /// the elements. |
97 | unsafe fn ffi_type_array_create<I>(elements: I) -> Owned<TypeArray_> |
98 | where |
99 | I: ExactSizeIterator<Item = Type>, |
100 | { |
101 | let size: usize = elements.len(); |
102 | let new: *mut *mut ffi_type = ffi_type_array_create_empty(len:size); |
103 | for (i: usize, element: Type) in elements.enumerate() { |
104 | *new.add(count:i) = *element.0; |
105 | mem::forget(element); |
106 | } |
107 | |
108 | new |
109 | } |
110 | |
111 | /// Creates a struct type from a raw array of element types. |
112 | unsafe fn ffi_type_struct_create_raw( |
113 | elements: Owned<TypeArray_>, |
114 | size: usize, |
115 | alignment: u16, |
116 | ) -> Owned<Type_> { |
117 | let new: *mut ffi_type = libc::malloc(size:mem::size_of::<low::ffi_type>()) as Type_; |
118 | assert!(!new.is_null(), "ffi_type_struct_create_raw: out of memory" ); |
119 | |
120 | (*new).size = size; |
121 | (*new).alignment = alignment; |
122 | (*new).type_ = low::type_tag::STRUCT; |
123 | (*new).elements = elements; |
124 | |
125 | new |
126 | } |
127 | |
128 | /// Creates a struct `ffi_type` with the given elements. Takes ownership |
129 | /// of the elements. |
130 | unsafe fn ffi_type_struct_create<I>(elements: I) -> Owned<Type_> |
131 | where |
132 | I: ExactSizeIterator<Item = Type>, |
133 | { |
134 | ffi_type_struct_create_raw(elements:ffi_type_array_create(elements), size:0, alignment:0) |
135 | } |
136 | |
137 | /// Makes a copy of a type array. |
138 | unsafe fn ffi_type_array_clone(old: TypeArray_) -> Owned<TypeArray_> { |
139 | let size: usize = ffi_type_array_len(array:old); |
140 | let new: *mut *mut ffi_type = ffi_type_array_create_empty(len:size); |
141 | |
142 | for i: usize in 0..size { |
143 | *new.add(count:i) = ffi_type_clone(*old.add(count:i)); |
144 | } |
145 | |
146 | new |
147 | } |
148 | |
149 | /// Makes a copy of a type. |
150 | unsafe fn ffi_type_clone(old: Type_) -> Owned<Type_> { |
151 | if (*old).type_ == low::type_tag::STRUCT { |
152 | let low::ffi_type { |
153 | alignment: u16, |
154 | elements: *mut *mut ffi_type, |
155 | size: usize, |
156 | .. |
157 | } = *old; |
158 | let new: *mut ffi_type = ffi_type_struct_create_raw(elements:ffi_type_array_clone(old:elements), size, alignment); |
159 | new |
160 | } else { |
161 | old |
162 | } |
163 | } |
164 | |
165 | /// Destroys a `TypeArray_` and all of its elements. |
166 | unsafe fn ffi_type_array_destroy(victim: Owned<TypeArray_>) { |
167 | let mut current: *mut *mut ffi_type = victim; |
168 | while !(*current).is_null() { |
169 | ffi_type_destroy(*current); |
170 | current = current.offset(count:1); |
171 | } |
172 | |
173 | libc::free(victim as *mut libc::c_void); |
174 | } |
175 | |
176 | /// Destroys a `Type_` if it was dynamically allocated. |
177 | unsafe fn ffi_type_destroy(victim: Owned<Type_>) { |
178 | if (*victim).type_ == low::type_tag::STRUCT { |
179 | ffi_type_array_destroy((*victim).elements); |
180 | libc::free(victim as *mut libc::c_void); |
181 | } |
182 | } |
183 | |
184 | impl Drop for Type { |
185 | fn drop(&mut self) { |
186 | unsafe { ffi_type_destroy(*self.0) } |
187 | } |
188 | } |
189 | |
190 | impl Drop for TypeArray { |
191 | fn drop(&mut self) { |
192 | unsafe { ffi_type_array_destroy(*self.0) } |
193 | } |
194 | } |
195 | |
196 | impl Clone for Type { |
197 | fn clone(&self) -> Self { |
198 | Type(unsafe { Unique::new(ptr:ffi_type_clone(*self.0)) }) |
199 | } |
200 | } |
201 | |
202 | impl Clone for TypeArray { |
203 | fn clone(&self) -> Self { |
204 | TypeArray(unsafe { Unique::new(ptr:ffi_type_array_clone(*self.0)) }) |
205 | } |
206 | } |
207 | |
208 | macro_rules! match_size_signed { |
209 | ( $name:ident ) => { |
210 | match mem::size_of::<libc::$name>() { |
211 | 1 => Self::i8(), |
212 | 2 => Self::i16(), |
213 | 4 => Self::i32(), |
214 | 8 => Self::i64(), |
215 | _ => panic!("Strange size for C type" ), |
216 | } |
217 | }; |
218 | } |
219 | |
220 | macro_rules! match_size_unsigned { |
221 | ( $name:ident ) => { |
222 | match mem::size_of::<libc::$name>() { |
223 | 1 => Self::u8(), |
224 | 2 => Self::u16(), |
225 | 4 => Self::u32(), |
226 | 8 => Self::u64(), |
227 | _ => panic!("Strange size for C type" ), |
228 | } |
229 | }; |
230 | } |
231 | |
232 | impl Type { |
233 | /// Returns the representation of the C `void` type. |
234 | /// |
235 | /// This is used only for the return type of a [CIF](super::Cif), |
236 | /// not for an argument or struct member. |
237 | pub fn void() -> Self { |
238 | Type(unsafe { Unique::new(&mut low::types::void) }) |
239 | } |
240 | |
241 | /// Returns the unsigned 8-bit numeric type. |
242 | pub fn u8() -> Self { |
243 | Type(unsafe { Unique::new(&mut low::types::uint8) }) |
244 | } |
245 | |
246 | /// Returns the signed 8-bit numeric type. |
247 | pub fn i8() -> Self { |
248 | Type(unsafe { Unique::new(&mut low::types::sint8) }) |
249 | } |
250 | |
251 | /// Returns the unsigned 16-bit numeric type. |
252 | pub fn u16() -> Self { |
253 | Type(unsafe { Unique::new(&mut low::types::uint16) }) |
254 | } |
255 | |
256 | /// Returns the signed 16-bit numeric type. |
257 | pub fn i16() -> Self { |
258 | Type(unsafe { Unique::new(&mut low::types::sint16) }) |
259 | } |
260 | |
261 | /// Returns the unsigned 32-bit numeric type. |
262 | pub fn u32() -> Self { |
263 | Type(unsafe { Unique::new(&mut low::types::uint32) }) |
264 | } |
265 | |
266 | /// Returns the signed 32-bit numeric type. |
267 | pub fn i32() -> Self { |
268 | Type(unsafe { Unique::new(&mut low::types::sint32) }) |
269 | } |
270 | |
271 | /// Returns the unsigned 64-bit numeric type. |
272 | pub fn u64() -> Self { |
273 | Type(unsafe { Unique::new(&mut low::types::uint64) }) |
274 | } |
275 | |
276 | /// Returns the signed 64-bit numeric type. |
277 | pub fn i64() -> Self { |
278 | Type(unsafe { Unique::new(&mut low::types::sint64) }) |
279 | } |
280 | |
281 | #[cfg (target_pointer_width = "16" )] |
282 | /// Returns the C equivalent of Rust `usize` (`u16`). |
283 | pub fn usize() -> Self { |
284 | Self::u16() |
285 | } |
286 | |
287 | #[cfg (target_pointer_width = "16" )] |
288 | /// Returns the C equivalent of Rust `isize` (`i16`). |
289 | pub fn isize() -> Self { |
290 | Self::i16() |
291 | } |
292 | |
293 | #[cfg (target_pointer_width = "32" )] |
294 | /// Returns the C equivalent of Rust `usize` (`u32`). |
295 | pub fn usize() -> Self { |
296 | Self::u32() |
297 | } |
298 | |
299 | #[cfg (target_pointer_width = "32" )] |
300 | /// Returns the C equivalent of Rust `isize` (`i32`). |
301 | pub fn isize() -> Self { |
302 | Self::i32() |
303 | } |
304 | |
305 | #[cfg (target_pointer_width = "64" )] |
306 | /// Returns the C equivalent of Rust `usize` (`u64`). |
307 | pub fn usize() -> Self { |
308 | Self::u64() |
309 | } |
310 | |
311 | #[cfg (target_pointer_width = "64" )] |
312 | /// Returns the C equivalent of Rust `isize` (`i64`). |
313 | pub fn isize() -> Self { |
314 | Self::i64() |
315 | } |
316 | |
317 | /// Returns the C `signed char` type. |
318 | pub fn c_schar() -> Self { |
319 | match_size_signed!(c_schar) |
320 | } |
321 | |
322 | /// Returns the C `unsigned char` type. |
323 | pub fn c_uchar() -> Self { |
324 | match_size_unsigned!(c_uchar) |
325 | } |
326 | |
327 | /// Returns the C `short` type. |
328 | pub fn c_short() -> Self { |
329 | match_size_signed!(c_short) |
330 | } |
331 | |
332 | /// Returns the C `unsigned short` type. |
333 | pub fn c_ushort() -> Self { |
334 | match_size_unsigned!(c_ushort) |
335 | } |
336 | |
337 | /// Returns the C `int` type. |
338 | pub fn c_int() -> Self { |
339 | match_size_signed!(c_int) |
340 | } |
341 | |
342 | /// Returns the C `unsigned int` type. |
343 | pub fn c_uint() -> Self { |
344 | match_size_unsigned!(c_uint) |
345 | } |
346 | |
347 | /// Returns the C `long` type. |
348 | pub fn c_long() -> Self { |
349 | match_size_signed!(c_long) |
350 | } |
351 | |
352 | /// Returns the C `unsigned long` type. |
353 | pub fn c_ulong() -> Self { |
354 | match_size_unsigned!(c_ulong) |
355 | } |
356 | |
357 | /// Returns the C `longlong` type. |
358 | pub fn c_longlong() -> Self { |
359 | match_size_signed!(c_longlong) |
360 | } |
361 | |
362 | /// Returns the C `unsigned longlong` type. |
363 | pub fn c_ulonglong() -> Self { |
364 | match_size_unsigned!(c_ulonglong) |
365 | } |
366 | |
367 | /// Returns the C `float` (32-bit floating point) type. |
368 | pub fn f32() -> Self { |
369 | Type(unsafe { Unique::new(&mut low::types::float) }) |
370 | } |
371 | |
372 | /// Returns the C `double` (64-bit floating point) type. |
373 | pub fn f64() -> Self { |
374 | Type(unsafe { Unique::new(&mut low::types::double) }) |
375 | } |
376 | |
377 | /// Returns the C `void*` type, for passing any kind of pointer. |
378 | pub fn pointer() -> Self { |
379 | Type(unsafe { Unique::new(&mut low::types::pointer) }) |
380 | } |
381 | |
382 | /// Returns the C `long double` (extended-precision floating point) type. |
383 | #[cfg (not(any(target_arch = "arm" , target_arch = "aarch64" )))] |
384 | pub fn longdouble() -> Self { |
385 | Type(unsafe { Unique::new(&mut low::types::longdouble) }) |
386 | } |
387 | |
388 | /// Returns the C `_Complex float` type. |
389 | /// |
390 | /// This item is enabled by `#[cfg(feature = "complex")]`. |
391 | #[cfg (feature = "complex" )] |
392 | pub fn c32() -> Self { |
393 | Type(unsafe { Unique::new(&mut low::types::complex_float) }) |
394 | } |
395 | |
396 | /// Returns the C `_Complex double` type. |
397 | /// |
398 | /// This item is enabled by `#[cfg(feature = "complex")]`. |
399 | #[cfg (feature = "complex" )] |
400 | pub fn c64() -> Self { |
401 | Type(unsafe { Unique::new(&mut low::types::complex_double) }) |
402 | } |
403 | |
404 | /// Returns the C `_Complex long double` type. |
405 | /// |
406 | /// This item is enabled by `#[cfg(feature = "complex")]`. |
407 | #[cfg (feature = "complex" )] |
408 | #[cfg (not(all(target_arch = "arm" )))] |
409 | pub fn complex_longdouble() -> Self { |
410 | Type(unsafe { Unique::new(&mut low::types::complex_longdouble) }) |
411 | } |
412 | |
413 | /// Constructs a structure type whose fields have the given types. |
414 | pub fn structure<I>(fields: I) -> Self |
415 | where |
416 | I: IntoIterator<Item = Type>, |
417 | I::IntoIter: ExactSizeIterator<Item = Type>, |
418 | { |
419 | Type(unsafe { Unique::new(ffi_type_struct_create(fields.into_iter())) }) |
420 | } |
421 | |
422 | /// Gets a raw pointer to the underlying [`low::ffi_type`]. |
423 | /// |
424 | /// This method may be useful for interacting with the |
425 | /// [`low`](crate::low) and [`raw`](crate::raw) layers. |
426 | pub fn as_raw_ptr(&self) -> *mut low::ffi_type { |
427 | *self.0 |
428 | } |
429 | } |
430 | |
431 | impl TypeArray { |
432 | /// Constructs an array the given `Type`s. |
433 | pub fn new<I>(elements: I) -> Self |
434 | where |
435 | I: IntoIterator<Item = Type>, |
436 | I::IntoIter: ExactSizeIterator<Item = Type>, |
437 | { |
438 | TypeArray(unsafe { Unique::new(ptr:ffi_type_array_create(elements:elements.into_iter())) }) |
439 | } |
440 | |
441 | /// Gets a raw pointer to the underlying C array of |
442 | /// [`low::ffi_type`]s. |
443 | /// |
444 | /// The C array is null-terminated. |
445 | /// |
446 | /// This method may be useful for interacting with the |
447 | /// [`low`](crate::low) and [`raw`](crate::raw) layers. |
448 | pub fn as_raw_ptr(&self) -> *mut *mut low::ffi_type { |
449 | *self.0 |
450 | } |
451 | } |
452 | |
453 | #[cfg (test)] |
454 | mod test { |
455 | use super::*; |
456 | |
457 | #[test ] |
458 | fn create_u64() { |
459 | Type::u64(); |
460 | } |
461 | |
462 | #[test ] |
463 | fn clone_u64() { |
464 | let _ = Type::u64().clone().clone(); |
465 | } |
466 | |
467 | #[test ] |
468 | fn create_struct() { |
469 | Type::structure(vec![Type::i64(), Type::i64(), Type::u64()]); |
470 | } |
471 | |
472 | #[test ] |
473 | fn clone_struct() { |
474 | let _ = Type::structure(vec![Type::i64(), Type::i64(), Type::u64()]) |
475 | .clone() |
476 | .clone(); |
477 | } |
478 | } |
479 | |