fidl_next_codec/decode/
mod.rs

1// Copyright 2024 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5//! Provides decoding for FIDL types.
6
7mod error;
8
9pub use self::error::*;
10
11use crate::{Slot, WireF32, WireF64, WireI16, WireI32, WireI64, WireU16, WireU32, WireU64};
12
13/// Decodes a value from the given slot.
14///
15/// # Safety
16///
17/// If `decode` returns `Ok`, then the provided `slot` must now contain a valid
18/// value of the implementing type.
19pub unsafe trait Decode<D: ?Sized> {
20    /// Decodes a value into a slot using a decoder.
21    ///
22    /// If decoding succeeds, `slot` will contain a valid value. If decoding fails, an error will be
23    /// returned.
24    fn decode(slot: Slot<'_, Self>, decoder: &mut D) -> Result<(), DecodeError>;
25}
26
27macro_rules! impl_primitive {
28    ($ty:ty) => {
29        unsafe impl<D: ?Sized> Decode<D> for $ty {
30            #[inline]
31            fn decode(_: Slot<'_, Self>, _: &mut D) -> Result<(), DecodeError> {
32                Ok(())
33            }
34        }
35    };
36}
37
38macro_rules! impl_primitives {
39    ($($ty:ty),* $(,)?) => {
40        $(
41            impl_primitive!($ty);
42        )*
43    }
44}
45
46impl_primitives! {
47    (),
48
49    i8,
50    WireI16,
51    WireI32,
52    WireI64,
53
54    u8,
55    WireU16,
56    WireU32,
57    WireU64,
58
59    WireF32,
60    WireF64,
61}
62
63unsafe impl<D: ?Sized> Decode<D> for bool {
64    #[inline]
65    fn decode(slot: Slot<'_, Self>, _: &mut D) -> Result<(), DecodeError> {
66        let value = unsafe { slot.as_ptr().cast::<u8>().read() };
67        match value {
68            0 | 1 => (),
69            invalid => return Err(DecodeError::InvalidBool(invalid)),
70        }
71        Ok(())
72    }
73}
74
75unsafe impl<D: ?Sized, T: Decode<D>, const N: usize> Decode<D> for [T; N] {
76    fn decode(mut slot: Slot<'_, Self>, decoder: &mut D) -> Result<(), DecodeError> {
77        for i in 0..N {
78            T::decode(slot.index(i), decoder)?;
79        }
80        Ok(())
81    }
82}
83
84#[cfg(test)]
85mod tests {
86    use crate::{chunks, WireF32, WireF64, WireI16, WireI32, WireI64, WireU16, WireU32, WireU64};
87
88    use crate::testing::assert_decoded;
89    use crate::wire::{WireBox, WireString, WireVector};
90    use crate::{WireOptionalString, WireOptionalVector};
91
92    #[test]
93    fn decode_bool() {
94        assert_decoded::<bool>(&mut chunks![0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00], |x| {
95            assert!(*x)
96        });
97        assert_decoded::<bool>(&mut chunks![0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00], |x| {
98            assert!(!*x)
99        });
100    }
101
102    #[test]
103    fn decode_ints() {
104        assert_decoded::<u8>(&mut chunks![0xa3, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00], |x| {
105            assert_eq!(*x, 0xa3u8)
106        });
107        assert_decoded::<i8>(&mut chunks![0xbb, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00], |x| {
108            assert_eq!(*x, -0x45i8)
109        });
110
111        assert_decoded::<WireU16>(
112            &mut chunks![0x34, 0x12, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00],
113            |x| assert_eq!(*x, 0x1234u16),
114        );
115        assert_decoded::<WireI16>(
116            &mut chunks![0xcc, 0xed, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00],
117            |x| assert_eq!(*x, -0x1234i16),
118        );
119
120        assert_decoded::<WireU32>(
121            &mut chunks![0x78, 0x56, 0x34, 0x12, 0x00, 0x00, 0x00, 0x00],
122            |x| assert_eq!(*x, 0x12345678u32),
123        );
124        assert_decoded::<WireI32>(
125            &mut chunks![0x88, 0xa9, 0xcb, 0xed, 0x00, 0x00, 0x00, 0x00],
126            |x| assert_eq!(*x, -0x12345678i32),
127        );
128
129        assert_decoded::<WireU64>(
130            &mut chunks![0xf0, 0xde, 0xbc, 0x9a, 0x78, 0x56, 0x34, 0x12],
131            |x| assert_eq!(*x, 0x123456789abcdef0u64),
132        );
133        assert_decoded::<WireI64>(
134            &mut chunks![0x10, 0x21, 0x43, 0x65, 0x87, 0xa9, 0xcb, 0xed],
135            |x| assert_eq!(*x, -0x123456789abcdef0i64),
136        );
137    }
138
139    #[test]
140    fn decode_floats() {
141        assert_decoded::<WireF32>(
142            &mut chunks![0xdb, 0x0f, 0x49, 0x40, 0x00, 0x00, 0x00, 0x00],
143            |x| assert_eq!(*x, ::core::f32::consts::PI),
144        );
145        assert_decoded::<WireF64>(
146            &mut chunks![0x18, 0x2d, 0x44, 0x54, 0xfb, 0x21, 0x09, 0x40],
147            |x| assert_eq!(*x, ::core::f64::consts::PI),
148        );
149    }
150
151    #[test]
152    fn decode_box() {
153        assert_decoded::<WireBox<WireU64>>(
154            &mut chunks![0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00],
155            |x| assert_eq!(x.as_ref(), None),
156        );
157        assert_decoded::<WireBox<WireU64>>(
158            &mut chunks![
159                0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf0, 0xde, 0xbc, 0x9a, 0x78, 0x56,
160                0x34, 0x12,
161            ],
162            |x| assert_eq!(*x.as_ref().unwrap(), 0x123456789abcdef0u64),
163        );
164    }
165
166    #[test]
167    fn decode_vec() {
168        assert_decoded::<WireOptionalVector<WireU32>>(
169            &mut chunks![
170                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
171                0x00, 0x00,
172            ],
173            |x| assert!(x.as_ref().is_none()),
174        );
175        assert_decoded::<WireVector<WireU32>>(
176            &mut chunks![
177                0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
178                0xff, 0xff, 0x78, 0x56, 0x34, 0x12, 0xf0, 0xde, 0xbc, 0x9a,
179            ],
180            |x| assert_eq!(x.as_slice(), [0x12345678, 0x9abcdef0].as_slice(),),
181        );
182        assert_decoded::<WireVector<WireU32>>(
183            &mut chunks![
184                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
185                0xff, 0xff,
186            ],
187            |x| assert_eq!(x.len(), 0),
188        );
189    }
190
191    #[test]
192    fn decode_string() {
193        assert_decoded::<WireOptionalString>(
194            &mut chunks![
195                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
196                0x00, 0x00,
197            ],
198            |x| assert!(x.is_none()),
199        );
200        assert_decoded::<WireString>(
201            &mut chunks![
202                0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
203                0xff, 0xff, 0x30, 0x31, 0x32, 0x33, 0x00, 0x00, 0x00, 0x00,
204            ],
205            |x| assert_eq!(x.as_str(), "0123"),
206        );
207        assert_decoded::<WireString>(
208            &mut chunks![
209                0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
210                0xff, 0xff,
211            ],
212            |x| assert_eq!(x.len(), 0),
213        );
214    }
215}
fidl_next_codec/decode/mod.rs

fidl_next_codec/decode/
mod.rs
