saltlick 0.5.0

A library for encrypting and decrypting file streams using libsodium
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
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

// Copyright (c) 2020, Nick Stevens <nick@bitcurry.com>
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/license/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

use crate::commonio::CommonOps;
use futures::ready;
use std::{
    pin::Pin,
    task::{Context, Poll},
};
use tokio::io::{AsyncBufRead, AsyncWrite, ReadBuf};

pub(crate) fn poll_read<R, Ops>(
    mut reader: Pin<&mut R>,
    cx: &mut Context<'_>,
    ops: &mut Ops,
    output: &mut ReadBuf<'_>,
) -> Poll<std::io::Result<()>>
where
    R: AsyncBufRead,
    Ops: CommonOps,
{
    loop {
        if ops.is_finalized() || output.remaining() == 0 {
            return Poll::Ready(Ok(()));
        }

        let eof;
        let (rd, wr) = {
            let input = ready!(reader.as_mut().poll_fill_buf(cx))?;
            eof = input.is_empty();
            ops.run(input, output.initialize_unfilled())?
        };
        reader.as_mut().consume(rd);
        output.advance(wr);

        if wr == 0 {
            if eof && !ops.is_finalized() {
                let wr = ops.finalize(output.initialize_unfilled())?;
                output.advance(wr);
            } else {
                continue;
            }
        } else {
            return Poll::Ready(Ok(()));
        }
    }
}

#[derive(Debug)]
pub(crate) struct AsyncBuffer {
    available: usize,
    buffer: Box<[u8]>,
    consumed: usize,
}

impl AsyncBuffer {
    pub fn new(capacity: usize) -> AsyncBuffer {
        AsyncBuffer {
            available: 0,
            buffer: vec![0u8; capacity].into_boxed_slice(),
            consumed: 0,
        }
    }

    pub fn poll_flush<W: AsyncWrite>(
        &mut self,
        mut writer: Pin<&mut W>,
        cx: &mut Context<'_>,
    ) -> Poll<std::io::Result<()>> {
        while self.available - self.consumed > 0 {
            let n = ready!(writer
                .as_mut()
                .poll_write(cx, &self.buffer[self.consumed..self.available]))?;
            if n == 0 {
                return Poll::Ready(Err(std::io::Error::new(
                    std::io::ErrorKind::WriteZero,
                    "failed to write the buffered data",
                )));
            } else {
                self.consumed += n;
            }
        }
        Poll::Ready(Ok(()))
    }
}
pub(crate) fn poll_write<W, Ops>(
    mut writer: Pin<&mut W>,
    cx: &mut Context<'_>,
    ops: &mut Ops,
    buffer: &mut AsyncBuffer,
    input: &[u8],
) -> Poll<std::io::Result<usize>>
where
    W: AsyncWrite,
    Ops: CommonOps,
{
    if input.is_empty() {
        return Poll::Ready(Ok(0));
    }

    // All buffered content needs to be flushed before writing because we give
    // the whole buffer to the crypter.
    ready!(buffer.poll_flush(writer.as_mut(), cx))?;

    loop {
        let (rd, wr) = ops.run(input, &mut buffer.buffer)?;
        buffer.available = wr;
        buffer.consumed = 0;
        if rd > 0 {
            return Poll::Ready(Ok(rd));
        } else {
            ready!(buffer.poll_flush(writer.as_mut(), cx))?;
        }
    }
}

pub(crate) fn poll_flush<W>(
    mut writer: Pin<&mut W>,
    cx: &mut Context<'_>,
    buffer: &mut AsyncBuffer,
) -> Poll<std::io::Result<()>>
where
    W: AsyncWrite,
{
    ready!(buffer.poll_flush(writer.as_mut(), cx))?;
    writer.poll_flush(cx)
}

pub(crate) fn poll_shutdown<W, Ops>(
    mut writer: Pin<&mut W>,
    cx: &mut Context<'_>,
    ops: &mut Ops,
    buffer: &mut AsyncBuffer,
) -> Poll<std::io::Result<()>>
where
    W: AsyncWrite,
    Ops: CommonOps,
{
    ready!(buffer.poll_flush(writer.as_mut(), cx))?;
    loop {
        let (_, wr) = ops.run(&[], &mut buffer.buffer)?;
        buffer.available = wr;
        buffer.consumed = 0;
        ready!(buffer.poll_flush(writer.as_mut(), cx))?;
        if wr == 0 {
            break;
        }
    }
    loop {
        let wr = ops.finalize(&mut buffer.buffer)?;
        buffer.available = wr;
        buffer.consumed = 0;
        ready!(buffer.poll_flush(writer.as_mut(), cx))?;
        if wr == 0 {
            break;
        }
    }
    ready!(writer.poll_shutdown(cx))?;
    Poll::Ready(Ok(()))
}