rsyn 0.0.1

[pre-alpha] Wire-compatible rsync client
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

// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Read and write rsync's integer encoding scheme: u8, i32, i64, and byte strings.

use std::io;
use std::io::prelude::*;

use anyhow::{Context, Error, Result};
#[allow(unused_imports)]
use log::{debug, error, info, trace, warn};

/// Read rsync data types from a wrapped stream.
pub struct ReadVarint {
    r: Box<dyn Read>,
}

impl ReadVarint {
    pub fn new(r: Box<dyn Read>) -> ReadVarint {
        ReadVarint { r }
    }

    pub fn read_u8(&mut self) -> io::Result<u8> {
        let mut b = [0u8];
        self.r.read_exact(&mut b).and(Ok(b[0]))
    }

    pub fn read_byte_string(&mut self, len: usize) -> io::Result<Vec<u8>> {
        let mut buf = vec![0; len];
        self.r.read_exact(&mut buf).and(Ok(buf))
    }

    pub fn read_i32(&mut self) -> io::Result<i32> {
        let mut buf = [0; 4];
        self.r.read_exact(&mut buf)?;
        let v = i32::from_le_bytes(buf);
        // debug!("Read {:#010x}", v);
        Ok(v)
    }

    pub fn read_i64(&mut self) -> io::Result<i64> {
        let v = self.read_i32()?;
        let v = if v != -1 {
            v as i64
        } else {
            let mut buf = [0; 8];
            self.r.read_exact(&mut buf)?;
            i64::from_le_bytes(buf)
        };
        // debug!("Read {:#020x}", v);
        Ok(v)
    }

    /// Return the underlying stream, consuming this wrapper.
    pub fn take(self) -> Box<dyn Read> {
        self.r
    }

    /// Destructively test that this is at the end of the input.
    ///
    /// Returns an error either on an IO error, or if there's any remaining
    /// data. The remaining data will be unreachable (and corrupt.) Returns Ok(())
    /// on a clean end.
    #[allow(unused)]
    pub fn check_for_eof(mut self) -> Result<()> {
        match self.read_u8().and(Ok(())) {
            Ok(_) => Err(Error::msg("Data found when we expected end of stream")),
            Err(e) if e.kind() == io::ErrorKind::UnexpectedEof => Ok(()),
            e => e.context("Error looking for end of stream"),
        }
    }
}

/// Write rsync low-level protocol variable integers.
pub struct WriteVarint {
    w: Box<dyn io::Write>,
}

impl WriteVarint {
    pub fn new(w: Box<dyn io::Write>) -> WriteVarint {
        WriteVarint { w }
    }

    pub fn write_i32(&mut self, v: i32) -> io::Result<()> {
        // debug!("Send {:#010x}", v);
        self.w.write_all(&v.to_le_bytes())
    }

    #[allow(unused)]
    pub fn write_u8(&mut self, v: u8) -> io::Result<()> {
        // debug!("Send {:#04x}", v);
        self.w.write_all(&[v])
    }
}

#[cfg(test)]
mod test {
    use super::*;

    fn make_rv(s: &'static [u8]) -> ReadVarint {
        ReadVarint::new(Box::new(s))
    }

    #[test]
    fn read_i64() {
        let mut rv = make_rv(&[0x10, 0, 0, 0]);
        assert_eq!(rv.read_i64().unwrap(), 0x10);

        let mut rv = make_rv(&[
            0xff, 0xff, 0xff, 0xff, 0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
        ]);
        assert_eq!(rv.read_i64().unwrap(), 0x7766554433221100);
        rv.check_for_eof().unwrap();
    }
}