bytecheck 0.6.11

Derive macro for bytecheck
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81

bytecheck is a type validation framework for Rust.

## bytecheck in action

```rust
use bytecheck::CheckBytes;

#[derive(CheckBytes, Debug)]
struct Test {
    a: u32,
    b: bool,
    c: char,
}

#[repr(C, align(16))]
struct Aligned<const N: usize>([u8; N]);

macro_rules! bytes {
    ($($byte:literal,)*) => {
        (&Aligned([$($byte,)*]).0 as &[u8]).as_ptr()
    };
    ($($byte:literal),*) => {
        bytes!($($byte,)*)
    };
}

fn main() {
    // This type is laid out as (u32, char, bool)
    unsafe {
        // These are valid bytes for (0, 'x', true)
        Test::check_bytes(
            bytes![
                0u8, 0u8, 0u8, 0u8, 0x78u8, 0u8, 0u8, 0u8,
                1u8, 255u8, 255u8, 255u8, 255u8, 255u8, 255u8, 255u8
            ].cast(),
            &()
        ).unwrap();

        // Changing the bytes for the u32 is OK, any bytes are a valid u32
        Test::check_bytes(
            bytes![
                42u8, 16u8, 20u8, 3u8, 0x78u8, 0u8, 0u8, 0u8,
                1u8, 255u8, 255u8, 255u8, 255u8, 255u8, 255u8, 255u8
            ].cast(),
            &()
        ).unwrap();

        // Characters outside the valid ranges are invalid
        Test::check_bytes(
            bytes![
                0u8, 0u8, 0u8, 0u8, 0x00u8, 0xd8u8, 0u8, 0u8,
                1u8, 255u8, 255u8, 255u8, 255u8, 255u8, 255u8, 255u8
            ].cast(),
            &()
        ).unwrap_err();
        Test::check_bytes(
            bytes![
                0u8, 0u8, 0u8, 0u8, 0x00u8, 0x00u8, 0x11u8, 0u8,
                1u8, 255u8, 255u8, 255u8, 255u8, 255u8, 255u8, 255u8
            ].cast(),
            &()
        ).unwrap_err();

        // 0 is a valid boolean value (false) but 2 is not
        Test::check_bytes(
            bytes![
                0u8, 0u8, 0u8, 0u8, 0x78u8, 0u8, 0u8, 0u8,
                0u8, 255u8, 255u8, 255u8, 255u8, 255u8, 255u8, 255u8
            ].cast(),
            &()
        ).unwrap();
        Test::check_bytes(
            bytes![
                0u8, 0u8, 0u8, 0u8, 0x78u8, 0u8, 0u8, 0u8,
                2u8, 255u8, 255u8, 255u8, 255u8, 255u8, 255u8, 255u8
            ].cast(),
            &()
        ).unwrap_err();
    }
}
```