1 #![allow(clippy::unnecessary_cast)]
2 #![allow(clippy::manual_slice_size_calculation)]
3
4 use core::mem::size_of;
5
6 use bytemuck::*;
7
8 #[test]
test_try_cast_slice()9 fn test_try_cast_slice() {
10 // some align4 data
11 let u32_slice: &[u32] = &[4, 5, 6];
12 // the same data as align1
13 let the_bytes: &[u8] = try_cast_slice(u32_slice).unwrap();
14
15 assert_eq!(
16 u32_slice.as_ptr() as *const u32 as usize,
17 the_bytes.as_ptr() as *const u8 as usize
18 );
19 assert_eq!(
20 u32_slice.len() * size_of::<u32>(),
21 the_bytes.len() * size_of::<u8>()
22 );
23
24 // by taking one byte off the front, we're definitely mis-aligned for u32.
25 let mis_aligned_bytes = &the_bytes[1..];
26 assert_eq!(
27 try_cast_slice::<u8, u32>(mis_aligned_bytes),
28 Err(PodCastError::TargetAlignmentGreaterAndInputNotAligned)
29 );
30
31 // by taking one byte off the end, we're aligned but would have slop bytes for
32 // u32
33 let the_bytes_len_minus1 = the_bytes.len() - 1;
34 let slop_bytes = &the_bytes[..the_bytes_len_minus1];
35 assert_eq!(
36 try_cast_slice::<u8, u32>(slop_bytes),
37 Err(PodCastError::OutputSliceWouldHaveSlop)
38 );
39
40 // if we don't mess with it we can up-alignment cast
41 try_cast_slice::<u8, u32>(the_bytes).unwrap();
42 }
43
44 #[test]
test_try_cast_slice_mut()45 fn test_try_cast_slice_mut() {
46 // some align4 data
47 let u32_slice: &mut [u32] = &mut [4, 5, 6];
48 let u32_len = u32_slice.len();
49 let u32_ptr = u32_slice.as_ptr();
50
51 // the same data as align1
52 let the_bytes: &mut [u8] = try_cast_slice_mut(u32_slice).unwrap();
53 let the_bytes_len = the_bytes.len();
54 let the_bytes_ptr = the_bytes.as_ptr();
55
56 assert_eq!(
57 u32_ptr as *const u32 as usize,
58 the_bytes_ptr as *const u8 as usize
59 );
60 assert_eq!(u32_len * size_of::<u32>(), the_bytes_len * size_of::<u8>());
61
62 // by taking one byte off the front, we're definitely mis-aligned for u32.
63 let mis_aligned_bytes = &mut the_bytes[1..];
64 assert_eq!(
65 try_cast_slice_mut::<u8, u32>(mis_aligned_bytes),
66 Err(PodCastError::TargetAlignmentGreaterAndInputNotAligned)
67 );
68
69 // by taking one byte off the end, we're aligned but would have slop bytes for
70 // u32
71 let the_bytes_len_minus1 = the_bytes.len() - 1;
72 let slop_bytes = &mut the_bytes[..the_bytes_len_minus1];
73 assert_eq!(
74 try_cast_slice_mut::<u8, u32>(slop_bytes),
75 Err(PodCastError::OutputSliceWouldHaveSlop)
76 );
77
78 // if we don't mess with it we can up-alignment cast
79 try_cast_slice_mut::<u8, u32>(the_bytes).unwrap();
80 }
81
82 #[test]
test_types()83 fn test_types() {
84 let _: i32 = cast(1.0_f32);
85 let _: &mut i32 = cast_mut(&mut 1.0_f32);
86 let _: &i32 = cast_ref(&1.0_f32);
87 let _: &[i32] = cast_slice(&[1.0_f32]);
88 let _: &mut [i32] = cast_slice_mut(&mut [1.0_f32]);
89 //
90 let _: Result<i32, PodCastError> = try_cast(1.0_f32);
91 let _: Result<&mut i32, PodCastError> = try_cast_mut(&mut 1.0_f32);
92 let _: Result<&i32, PodCastError> = try_cast_ref(&1.0_f32);
93 let _: Result<&[i32], PodCastError> = try_cast_slice(&[1.0_f32]);
94 let _: Result<&mut [i32], PodCastError> = try_cast_slice_mut(&mut [1.0_f32]);
95 }
96
97 #[test]
test_bytes_of()98 fn test_bytes_of() {
99 assert_eq!(bytes_of(&0xaabbccdd_u32), &0xaabbccdd_u32.to_ne_bytes());
100 assert_eq!(
101 bytes_of_mut(&mut 0xaabbccdd_u32),
102 &mut 0xaabbccdd_u32.to_ne_bytes()
103 );
104 let mut a = 0xaabbccdd_u32;
105 let a_addr = &a as *const _ as usize;
106 // ensure addresses match.
107 assert_eq!(bytes_of(&a).as_ptr() as usize, a_addr);
108 assert_eq!(bytes_of_mut(&mut a).as_ptr() as usize, a_addr);
109 }
110
111 #[test]
test_try_from_bytes()112 fn test_try_from_bytes() {
113 let u32s = [0xaabbccdd, 0x11223344_u32];
114 let bytes = bytemuck::cast_slice::<u32, u8>(&u32s);
115 assert_eq!(try_from_bytes::<u32>(&bytes[..4]), Ok(&u32s[0]));
116 assert_eq!(
117 try_from_bytes::<u32>(&bytes[..5]),
118 Err(PodCastError::SizeMismatch)
119 );
120 assert_eq!(
121 try_from_bytes::<u32>(&bytes[..3]),
122 Err(PodCastError::SizeMismatch)
123 );
124 assert_eq!(
125 try_from_bytes::<u32>(&bytes[1..5]),
126 Err(PodCastError::TargetAlignmentGreaterAndInputNotAligned)
127 );
128 }
129
130 #[test]
test_try_from_bytes_mut()131 fn test_try_from_bytes_mut() {
132 let mut abcd = 0xaabbccdd;
133 let mut u32s = [abcd, 0x11223344_u32];
134 let bytes = bytemuck::cast_slice_mut::<u32, u8>(&mut u32s);
135 assert_eq!(try_from_bytes_mut::<u32>(&mut bytes[..4]), Ok(&mut abcd));
136 assert_eq!(try_from_bytes_mut::<u32>(&mut bytes[..4]), Ok(&mut abcd));
137 assert_eq!(
138 try_from_bytes_mut::<u32>(&mut bytes[..5]),
139 Err(PodCastError::SizeMismatch)
140 );
141 assert_eq!(
142 try_from_bytes_mut::<u32>(&mut bytes[..3]),
143 Err(PodCastError::SizeMismatch)
144 );
145 assert_eq!(
146 try_from_bytes::<u32>(&bytes[1..5]),
147 Err(PodCastError::TargetAlignmentGreaterAndInputNotAligned)
148 );
149 }
150
151 #[test]
test_from_bytes()152 fn test_from_bytes() {
153 let abcd = 0xaabbccdd_u32;
154 let aligned_bytes = bytemuck::bytes_of(&abcd);
155 assert_eq!(from_bytes::<u32>(aligned_bytes), &abcd);
156 assert!(core::ptr::eq(from_bytes(aligned_bytes), &abcd));
157 }
158
159 #[test]
test_from_bytes_mut()160 fn test_from_bytes_mut() {
161 let mut a = 0xaabbccdd_u32;
162 let a_addr = &a as *const _ as usize;
163 let aligned_bytes = bytemuck::bytes_of_mut(&mut a);
164 assert_eq!(*from_bytes_mut::<u32>(aligned_bytes), 0xaabbccdd_u32);
165 assert_eq!(
166 from_bytes_mut::<u32>(aligned_bytes) as *const u32 as usize,
167 a_addr
168 );
169 }
170
171 // like #[should_panic], but can be a part of another test, instead of requiring
172 // it to be it's own test.
173 macro_rules! should_panic {
174 ($ex:expr) => {
175 assert!(
176 std::panic::catch_unwind(|| {
177 let _ = $ex;
178 })
179 .is_err(),
180 concat!("should have panicked: `", stringify!($ex), "`")
181 );
182 };
183 }
184
185 #[test]
test_panics()186 fn test_panics() {
187 should_panic!(cast_slice::<u8, u32>(&[1u8, 2u8]));
188 should_panic!(cast_slice_mut::<u8, u32>(&mut [1u8, 2u8]));
189 should_panic!(from_bytes::<u32>(&[1u8, 2]));
190 should_panic!(from_bytes::<u32>(&[1u8, 2, 3, 4, 5]));
191 should_panic!(from_bytes_mut::<u32>(&mut [1u8, 2]));
192 should_panic!(from_bytes_mut::<u32>(&mut [1u8, 2, 3, 4, 5]));
193 // use cast_slice on some u32s to get some align>=4 bytes, so we can know
194 // we'll give from_bytes unaligned ones.
195 let aligned_bytes = bytemuck::cast_slice::<u32, u8>(&[0, 0]);
196 should_panic!(from_bytes::<u32>(&aligned_bytes[1..5]));
197 }
198
199 #[test]
test_zsts()200 fn test_zsts() {
201 #[derive(Debug, Clone, Copy)]
202 struct MyZst;
203 unsafe impl Zeroable for MyZst {}
204 unsafe impl Pod for MyZst {}
205 assert_eq!(42, cast_slice::<(), MyZst>(&[(); 42]).len());
206 assert_eq!(42, cast_slice_mut::<(), MyZst>(&mut [(); 42]).len());
207 assert_eq!(0, cast_slice::<(), u8>(&[(); 42]).len());
208 assert_eq!(0, cast_slice_mut::<(), u8>(&mut [(); 42]).len());
209 assert_eq!(0, cast_slice::<u8, ()>(&[]).len());
210 assert_eq!(0, cast_slice_mut::<u8, ()>(&mut []).len());
211
212 assert_eq!(
213 PodCastError::OutputSliceWouldHaveSlop,
214 try_cast_slice::<u8, ()>(&[42]).unwrap_err()
215 );
216
217 assert_eq!(
218 PodCastError::OutputSliceWouldHaveSlop,
219 try_cast_slice_mut::<u8, ()>(&mut [42]).unwrap_err()
220 );
221 }
222
223 #[cfg(feature = "extern_crate_alloc")]
224 #[test]
test_boxed_slices()225 fn test_boxed_slices() {
226 let boxed_u8_slice: Box<[u8]> = Box::new([0, 1, u8::MAX, i8::MAX as u8]);
227 let boxed_i8_slice: Box<[i8]> = cast_slice_box::<u8, i8>(boxed_u8_slice);
228 assert_eq!(&*boxed_i8_slice, [0, 1, -1, i8::MAX]);
229
230 let result: Result<Box<[u16]>, (PodCastError, Box<[i8]>)> =
231 try_cast_slice_box(boxed_i8_slice);
232 let (error, boxed_i8_slice) =
233 result.expect_err("u16 and i8 have different alignment");
234 assert_eq!(error, PodCastError::AlignmentMismatch);
235
236 let result: Result<&[[i8; 3]], PodCastError> =
237 try_cast_slice(&*boxed_i8_slice);
238 let error =
239 result.expect_err("slice of [i8; 3] cannot be made from slice of 4 i8s");
240 assert_eq!(error, PodCastError::OutputSliceWouldHaveSlop);
241
242 let result: Result<Box<[[i8; 3]]>, (PodCastError, Box<[i8]>)> =
243 try_cast_slice_box(boxed_i8_slice);
244 let (error, boxed_i8_slice) =
245 result.expect_err("slice of [i8; 3] cannot be made from slice of 4 i8s");
246 assert_eq!(error, PodCastError::OutputSliceWouldHaveSlop);
247
248 let empty: Box<[()]> = cast_slice_box::<u8, ()>(Box::new([]));
249 assert!(empty.is_empty());
250
251 let result: Result<Box<[()]>, (PodCastError, Box<[i8]>)> =
252 try_cast_slice_box(boxed_i8_slice);
253 let (error, boxed_i8_slice) =
254 result.expect_err("slice of ZST cannot be made from slice of 4 u8s");
255 assert_eq!(error, PodCastError::OutputSliceWouldHaveSlop);
256
257 drop(boxed_i8_slice);
258
259 let empty: Box<[i8]> = cast_slice_box::<(), i8>(Box::new([]));
260 assert!(empty.is_empty());
261
262 let empty: Box<[i8]> = cast_slice_box::<(), i8>(Box::new([(); 42]));
263 assert!(empty.is_empty());
264 }
265
266 #[cfg(feature = "extern_crate_alloc")]
267 #[test]
test_rc_slices()268 fn test_rc_slices() {
269 use std::rc::Rc;
270 let rc_u8_slice: Rc<[u8]> = Rc::new([0, 1, u8::MAX, i8::MAX as u8]);
271 let rc_i8_slice: Rc<[i8]> = cast_slice_rc::<u8, i8>(rc_u8_slice);
272 assert_eq!(&*rc_i8_slice, [0, 1, -1, i8::MAX]);
273
274 let result: Result<Rc<[u16]>, (PodCastError, Rc<[i8]>)> =
275 try_cast_slice_rc(rc_i8_slice);
276 let (error, rc_i8_slice) =
277 result.expect_err("u16 and i8 have different alignment");
278 assert_eq!(error, PodCastError::AlignmentMismatch);
279
280 let result: Result<&[[i8; 3]], PodCastError> = try_cast_slice(&*rc_i8_slice);
281 let error =
282 result.expect_err("slice of [i8; 3] cannot be made from slice of 4 i8s");
283 assert_eq!(error, PodCastError::OutputSliceWouldHaveSlop);
284
285 let result: Result<Rc<[[i8; 3]]>, (PodCastError, Rc<[i8]>)> =
286 try_cast_slice_rc(rc_i8_slice);
287 let (error, rc_i8_slice) =
288 result.expect_err("slice of [i8; 3] cannot be made from slice of 4 i8s");
289 assert_eq!(error, PodCastError::OutputSliceWouldHaveSlop);
290
291 let empty: Rc<[()]> = cast_slice_rc::<u8, ()>(Rc::new([]));
292 assert!(empty.is_empty());
293
294 let result: Result<Rc<[()]>, (PodCastError, Rc<[i8]>)> =
295 try_cast_slice_rc(rc_i8_slice);
296 let (error, rc_i8_slice) =
297 result.expect_err("slice of ZST cannot be made from slice of 4 u8s");
298 assert_eq!(error, PodCastError::OutputSliceWouldHaveSlop);
299
300 drop(rc_i8_slice);
301
302 let empty: Rc<[i8]> = cast_slice_rc::<(), i8>(Rc::new([]));
303 assert!(empty.is_empty());
304
305 let empty: Rc<[i8]> = cast_slice_rc::<(), i8>(Rc::new([(); 42]));
306 assert!(empty.is_empty());
307 }
308
309 #[cfg(feature = "extern_crate_alloc")]
310 #[cfg(target_has_atomic = "ptr")]
311 #[test]
test_arc_slices()312 fn test_arc_slices() {
313 use std::sync::Arc;
314 let arc_u8_slice: Arc<[u8]> = Arc::new([0, 1, u8::MAX, i8::MAX as u8]);
315 let arc_i8_slice: Arc<[i8]> = cast_slice_arc::<u8, i8>(arc_u8_slice);
316 assert_eq!(&*arc_i8_slice, [0, 1, -1, i8::MAX]);
317
318 let result: Result<Arc<[u16]>, (PodCastError, Arc<[i8]>)> =
319 try_cast_slice_arc(arc_i8_slice);
320 let (error, arc_i8_slice) =
321 result.expect_err("u16 and i8 have different alignment");
322 assert_eq!(error, PodCastError::AlignmentMismatch);
323
324 let result: Result<&[[i8; 3]], PodCastError> = try_cast_slice(&*arc_i8_slice);
325 let error =
326 result.expect_err("slice of [i8; 3] cannot be made from slice of 4 i8s");
327 assert_eq!(error, PodCastError::OutputSliceWouldHaveSlop);
328
329 let result: Result<Arc<[[i8; 3]]>, (PodCastError, Arc<[i8]>)> =
330 try_cast_slice_arc(arc_i8_slice);
331 let (error, arc_i8_slice) =
332 result.expect_err("slice of [i8; 3] cannot be made from slice of 4 i8s");
333 assert_eq!(error, PodCastError::OutputSliceWouldHaveSlop);
334
335 let empty: Arc<[()]> = cast_slice_arc::<u8, ()>(Arc::new([]));
336 assert!(empty.is_empty());
337
338 let result: Result<Arc<[()]>, (PodCastError, Arc<[i8]>)> =
339 try_cast_slice_arc(arc_i8_slice);
340 let (error, arc_i8_slice) =
341 result.expect_err("slice of ZST cannot be made from slice of 4 u8s");
342 assert_eq!(error, PodCastError::OutputSliceWouldHaveSlop);
343
344 drop(arc_i8_slice);
345
346 let empty: Arc<[i8]> = cast_slice_arc::<(), i8>(Arc::new([]));
347 assert!(empty.is_empty());
348
349 let empty: Arc<[i8]> = cast_slice_arc::<(), i8>(Arc::new([(); 42]));
350 assert!(empty.is_empty());
351 }
352
353 #[cfg(feature = "extern_crate_alloc")]
354 #[test]
box_bytes_zst()355 fn box_bytes_zst() {
356 let x: BoxBytes = box_bytes_of(Box::new([0u8; 0]));
357 let _: Box<[u8]> = from_box_bytes(x);
358
359 let x: BoxBytes = box_bytes_of(Box::new([0u8; 0]));
360 let _: Box<[()]> = from_box_bytes(x);
361
362 let x: BoxBytes = box_bytes_of(Box::new([(); 0]));
363 let _: Box<[u8]> = from_box_bytes(x);
364
365 let x: BoxBytes = box_bytes_of(Box::new([0u8]));
366 let res: Result<Box<[()]>, _> = try_from_box_bytes(x);
367 assert_eq!(res.unwrap_err().0, PodCastError::OutputSliceWouldHaveSlop);
368
369 // regression test for dropping zero-sized BoxBytes
370 let _: BoxBytes = box_bytes_of(Box::new([0u8; 0]));
371 }
372