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

use pin_project_lite::pin_project;
use std::io::{IoSlice, Result};
use std::pin::Pin;
use std::task::{ready, Context, Poll};

use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};

pin_project! {
    /// An adapter that lets you inspect the data that's being read.
    ///
    /// This is useful for things like hashing data as it's read in.
    pub struct InspectReader<R, F> {
        #[pin]
        reader: R,
        f: F,
    }
}

impl<R, F> InspectReader<R, F> {
    /// Create a new `InspectReader`, wrapping `reader` and calling `f` for the
    /// new data supplied by each read call.
    ///
    /// The closure will only be called with an empty slice if the inner reader
    /// returns without reading data into the buffer. This happens at EOF, or if
    /// `poll_read` is called with a zero-size buffer.
    pub fn new(reader: R, f: F) -> InspectReader<R, F>
    where
        R: AsyncRead,
        F: FnMut(&[u8]),
    {
        InspectReader { reader, f }
    }

    /// Consumes the `InspectReader`, returning the wrapped reader
    pub fn into_inner(self) -> R {
        self.reader
    }
}

impl<R: AsyncRead, F: FnMut(&[u8])> AsyncRead for InspectReader<R, F> {
    fn poll_read(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &mut ReadBuf<'_>,
    ) -> Poll<Result<()>> {
        let me = self.project();
        let filled_length = buf.filled().len();
        ready!(me.reader.poll_read(cx, buf))?;
        (me.f)(&buf.filled()[filled_length..]);
        Poll::Ready(Ok(()))
    }
}

impl<R: AsyncWrite, F> AsyncWrite for InspectReader<R, F> {
    fn poll_write(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &[u8],
    ) -> Poll<std::result::Result<usize, std::io::Error>> {
        self.project().reader.poll_write(cx, buf)
    }

    fn poll_flush(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
    ) -> Poll<std::result::Result<(), std::io::Error>> {
        self.project().reader.poll_flush(cx)
    }

    fn poll_shutdown(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
    ) -> Poll<std::result::Result<(), std::io::Error>> {
        self.project().reader.poll_shutdown(cx)
    }

    fn poll_write_vectored(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        bufs: &[IoSlice<'_>],
    ) -> Poll<Result<usize>> {
        self.project().reader.poll_write_vectored(cx, bufs)
    }

    fn is_write_vectored(&self) -> bool {
        self.reader.is_write_vectored()
    }
}

pin_project! {
    /// An adapter that lets you inspect the data that's being written.
    ///
    /// This is useful for things like hashing data as it's written out.
    pub struct InspectWriter<W, F> {
        #[pin]
        writer: W,
        f: F,
    }
}

impl<W, F> InspectWriter<W, F> {
    /// Create a new `InspectWriter`, wrapping `write` and calling `f` for the
    /// data successfully written by each write call.
    ///
    /// The closure `f` will never be called with an empty slice. A vectored
    /// write can result in multiple calls to `f` - at most one call to `f` per
    /// buffer supplied to `poll_write_vectored`.
    pub fn new(writer: W, f: F) -> InspectWriter<W, F>
    where
        W: AsyncWrite,
        F: FnMut(&[u8]),
    {
        InspectWriter { writer, f }
    }

    /// Consumes the `InspectWriter`, returning the wrapped writer
    pub fn into_inner(self) -> W {
        self.writer
    }
}

impl<W: AsyncWrite, F: FnMut(&[u8])> AsyncWrite for InspectWriter<W, F> {
    fn poll_write(self: Pin<&mut Self>, cx: &mut Context<'_>, buf: &[u8]) -> Poll<Result<usize>> {
        let me = self.project();
        let res = me.writer.poll_write(cx, buf);
        if let Poll::Ready(Ok(count)) = res {
            if count != 0 {
                (me.f)(&buf[..count]);
            }
        }
        res
    }

    fn poll_flush(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>> {
        let me = self.project();
        me.writer.poll_flush(cx)
    }

    fn poll_shutdown(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<()>> {
        let me = self.project();
        me.writer.poll_shutdown(cx)
    }

    fn poll_write_vectored(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        bufs: &[IoSlice<'_>],
    ) -> Poll<Result<usize>> {
        let me = self.project();
        let res = me.writer.poll_write_vectored(cx, bufs);
        if let Poll::Ready(Ok(mut count)) = res {
            for buf in bufs {
                if count == 0 {
                    break;
                }
                let size = count.min(buf.len());
                if size != 0 {
                    (me.f)(&buf[..size]);
                    count -= size;
                }
            }
        }
        res
    }

    fn is_write_vectored(&self) -> bool {
        self.writer.is_write_vectored()
    }
}

impl<W: AsyncRead, F> AsyncRead for InspectWriter<W, F> {
    fn poll_read(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
        buf: &mut ReadBuf<'_>,
    ) -> Poll<std::io::Result<()>> {
        self.project().writer.poll_read(cx, buf)
    }
}