rmp/encode/
buffer.rs

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
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
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
//! Implementation of the [`ByteBuf`] type

use super::RmpWrite;
use alloc::vec::Vec;
#[cfg(not(feature = "std"))]
use core::fmt::{self, Display, Formatter};

/// An error returned from writing to `&mut [u8]` (a byte buffer of fixed capacity) on no_std
///
/// In feature="std", capacity overflow in `<&mut [u8] as std::io::Write>::write_exact()`
/// currently returns [`ErrorKind::WriteZero`](https://doc.rust-lang.org/std/io/enum.ErrorKind.html#variant.WriteZero).
///
/// Since no_std doesn't have std::io::Error we use this instead ;)
///
/// This is specific to `#[cfg(not(feature = "std"))]` so it is `#[doc(hidden)]`
#[derive(Debug)]
#[cfg(not(feature = "std"))]
#[doc(hidden)]
pub struct FixedBufCapacityOverflow {
    _priv: (),
}

/// An error returned from writing to `&mut [u8]`
///
/// Aliased for compatibility with `no_std` mode.
#[cfg(feature = "std")]
#[doc(hidden)]
pub type FixedBufCapacityOverflow = std::io::Error;

#[cfg(not(feature = "std"))]
impl Display for FixedBufCapacityOverflow {
    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
        // This is intentionally vauge because std::io::Error is
        // Doesn't make sense for no_std to have bettetr errors than std
        f.write_str("Capacity overflow for fixed-size byte buffer")
    }
}
#[cfg(not(feature = "std"))]
impl crate::encode::RmpWriteErr for FixedBufCapacityOverflow {}

/// Fallback implementation for fixed-capacity buffers
///
/// Only needed for no-std because we don't have
/// the blanket impl for `std::io::Write`
#[cfg(not(feature = "std"))]
impl<'a> RmpWrite for &'a mut [u8] {
    type Error = FixedBufCapacityOverflow;

    #[inline]
    fn write_bytes(&mut self, buf: &[u8]) -> Result<(), Self::Error> {
        let to_write = buf.len();
        let remaining = self.len();
        if to_write <= remaining {
            self[..to_write].copy_from_slice(buf);
            unsafe {
                //Cant use split_at or re-borrowing due to lifetime errors :(
                *self = core::slice::from_raw_parts_mut(
                    self.as_mut_ptr().add(to_write),
                    remaining - to_write,
                )
            }
            Ok(())
        } else {
            Err(FixedBufCapacityOverflow { _priv: () })
        }
    }
}

/// A wrapper around `Vec<u8>` to serialize more efficiently.
///
/// This has a specialized implementation of `RmpWrite`
/// It gives `std::convert::Infailable` for errors.
/// This is because writing to `Vec<T>` can only fail due to allocation.
///
/// This has the additional benefit of working on `#[no_std]`
///
/// See also [serde_bytes::ByteBuf](https://docs.rs/serde_bytes/0.11/serde_bytes/struct.ByteBuf.html)
#[derive(Debug, Clone, Default, Eq, PartialEq, Hash, Ord, PartialOrd)]
pub struct ByteBuf {
    bytes: Vec<u8>,
}
impl ByteBuf {
    /// Construct a new empty buffer
    #[inline]
    #[must_use]
    pub fn new() -> Self {
        ByteBuf { bytes: Vec::new() }
    }
    /// Construct a new buffer with the specified capacity
    ///
    /// See [`Vec::with_capacity`] for details
    #[inline]
    #[must_use]
    pub fn with_capacity(capacity: usize) -> Self {
        ByteBuf {
            bytes: Vec::with_capacity(capacity),
        }
    }
    /// Unwrap the underlying buffer of this vector
    #[inline]
    #[must_use]
    pub fn into_vec(self) -> Vec<u8> {
        self.bytes
    }
    /// Wrap the specified vector as a [`ByteBuf`]
    #[inline]
    #[must_use]
    pub fn from_vec(bytes: Vec<u8>) -> Self {
        ByteBuf { bytes }
    }
    /// Get a reference to this type as a [Vec]
    #[inline]
    #[must_use]
    pub fn as_vec(&self) -> &Vec<u8> {
        &self.bytes
    }
    /// Get a mutable reference to this type as a [Vec]
    #[inline]
    pub fn as_mut_vec(&mut self) -> &mut Vec<u8> {
        &mut self.bytes
    }
    /// Get a reference to this type as a slice of bytes (`&[u8]`)
    #[inline]
    #[must_use]
    pub fn as_slice(&self) -> &[u8] {
        &self.bytes
    }
}
impl AsRef<[u8]> for ByteBuf {
    fn as_ref(&self) -> &[u8] {
        &self.bytes
    }
}
impl AsRef<Vec<u8>> for ByteBuf {
    #[inline]
    fn as_ref(&self) -> &Vec<u8> {
        &self.bytes
    }
}
impl AsMut<Vec<u8>> for ByteBuf {
    #[inline]
    fn as_mut(&mut self) -> &mut Vec<u8> {
        &mut self.bytes
    }
}
impl From<ByteBuf> for Vec<u8> {
    #[inline]
    fn from(buf: ByteBuf) -> Self {
        buf.bytes
    }
}
impl From<Vec<u8>> for ByteBuf {
    #[inline]
    fn from(bytes: Vec<u8>) -> Self {
        ByteBuf { bytes }
    }
}

impl RmpWrite for ByteBuf {
    type Error = core::convert::Infallible;

    #[inline]
    fn write_u8(&mut self, val: u8) -> Result<(), Self::Error> {
        self.bytes.push(val);
        Ok(())
    }

    #[inline]
    fn write_bytes(&mut self, buf: &[u8]) -> Result<(), Self::Error> {
        self.bytes.extend_from_slice(buf);
        Ok(())
    }
}
#[cfg(not(feature = "std"))]
impl<'a> RmpWrite for Vec<u8> {
    type Error = core::convert::Infallible;

    #[inline]
    fn write_u8(&mut self, val: u8) -> Result<(), Self::Error> {
        self.push(val);
        Ok(())
    }

    #[inline]
    fn write_bytes(&mut self, buf: &[u8]) -> Result<(), Self::Error> {
        self.extend_from_slice(buf);
        Ok(())
    }
}