ring/io/
writer.rs

Help
1// Copyright 2018 Brian Smith.
2//
3// Permission to use, copy, modify, and/or distribute this software for any
4// purpose with or without fee is hereby granted, provided that the above
5// copyright notice and this permission notice appear in all copies.
6//
7// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
14
15use alloc::{boxed::Box, vec::Vec};
16
17pub trait Accumulator {
18    fn write_byte(&mut self, value: u8) -> Result<(), TooLongError>;
19    fn write_bytes(&mut self, value: &[u8]) -> Result<(), TooLongError>;
20}
21
22pub(super) struct LengthMeasurement {
23    len: usize,
24}
25
26impl From<LengthMeasurement> for usize {
27    fn from(len: LengthMeasurement) -> usize {
28        len.len
29    }
30}
31
32impl LengthMeasurement {
33    pub fn zero() -> Self {
34        Self { len: 0 }
35    }
36}
37
38impl Accumulator for LengthMeasurement {
39    fn write_byte(&mut self, _value: u8) -> Result<(), TooLongError> {
40        self.len = self.len.checked_add(1).ok_or_else(TooLongError::new)?;
41        Ok(())
42    }
43    fn write_bytes(&mut self, value: &[u8]) -> Result<(), TooLongError> {
44        self.len = self
45            .len
46            .checked_add(value.len())
47            .ok_or_else(TooLongError::new)?;
48        Ok(())
49    }
50}
51
52pub(super) struct Writer {
53    bytes: Vec<u8>,
54    requested_capacity: usize,
55}
56
57impl Writer {
58    pub(super) fn with_capacity(capacity: LengthMeasurement) -> Self {
59        Self {
60            bytes: Vec::with_capacity(capacity.len),
61            requested_capacity: capacity.len,
62        }
63    }
64}
65
66impl From<Writer> for Box<[u8]> {
67    fn from(writer: Writer) -> Self {
68        assert_eq!(writer.requested_capacity, writer.bytes.len());
69        writer.bytes.into_boxed_slice()
70    }
71}
72
73impl Accumulator for Writer {
74    fn write_byte(&mut self, value: u8) -> Result<(), TooLongError> {
75        self.bytes.push(value);
76        Ok(())
77    }
78    fn write_bytes(&mut self, value: &[u8]) -> Result<(), TooLongError> {
79        self.bytes.extend(value);
80        Ok(())
81    }
82}
83
84pub fn write_copy(
85    accumulator: &mut dyn Accumulator,
86    to_copy: untrusted::Input,
87) -> Result<(), TooLongError> {
88    accumulator.write_bytes(to_copy.as_slice_less_safe())
89}
90
91pub struct TooLongError(());
92
93impl TooLongError {
94    pub fn new() -> Self {
95        Self(())
96    }
97}
ring/io/writer.rs

ring/io/
writer.rs
