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

use super::{ObjectError, ObjectId, Result, WriteObject};
use crate::{
    backends::Backend,
    compress,
    crypto::{ChunkKey, CryptoProvider, Digest, RootKey},
    ChunkPointer,
};
use std::{
    io::{Seek, SeekFrom},
    sync::Arc,
};

#[derive(Clone)]
enum Mode {
    SealRoot(u64),
    Data,
}

pub trait Writer: Send {
    fn write_chunk(&mut self, hash: &Digest, data: &[u8]) -> Result<ChunkPointer>;
    fn flush(&mut self) -> Result<()>;
}

pub struct AEADWriter {
    backend: Arc<dyn Backend>,
    crypto: ChunkKey,
    object: WriteObject,
    mode: Mode,
}

impl AEADWriter {
    pub fn new(backend: Arc<dyn Backend>, crypto: ChunkKey) -> Self {
        let mut object = WriteObject::default();
        object.reset_id(&crypto);

        AEADWriter {
            backend,
            crypto,
            object,
            mode: Mode::Data,
        }
    }

    pub fn for_root(backend: Arc<dyn Backend>, crypto: RootKey, header_size: u64) -> Self {
        let mut object = WriteObject::default();
        object.reset_id(&crypto);
        object.seek(SeekFrom::Start(header_size)).unwrap();

        AEADWriter {
            backend,
            crypto,
            object,
            mode: Mode::SealRoot(header_size),
        }
    }

    pub(crate) fn flush_root_head(&mut self, id: ObjectId, head: &[u8]) -> Result<()> {
        self.object.set_id(id);
        self.object.write_head(head);
        self.object.finalize(&self.crypto);
        self.backend.write_object(&self.object)?;

        self.object.reset_id(&self.crypto);
        self.object.seek(match self.mode {
            Mode::SealRoot(header) => SeekFrom::Start(header),
            Mode::Data => SeekFrom::Start(0),
        })?;

        Ok(())
    }
}

impl Clone for AEADWriter {
    fn clone(&self) -> Self {
        let mut object = self.object.clone();
        object.set_id(ObjectId::new(&self.crypto));

        AEADWriter {
            object,
            backend: self.backend.clone(),
            crypto: self.crypto.clone(),
            mode: self.mode.clone(),
        }
    }
}

impl Drop for AEADWriter {
    fn drop(&mut self) {
        if self.object.position() > 0 {
            self.flush().unwrap();
        }
    }
}

impl Writer for AEADWriter {
    fn write_chunk(&mut self, hash: &Digest, data: &[u8]) -> Result<ChunkPointer> {
        let size = {
            let buffer = self.object.tail_mut();

            match compress::compress_into(data, buffer) {
                Ok(size) => size,
                Err(_e) => {
                    self.flush()?;

                    let buffer = self.object.tail_mut();
                    compress::compress_into(data, buffer).map_err(|_| {
                        ObjectError::ChunkTooLarge {
                            size: data.len(),
                            max_size: ((self.object.capacity() - 16 - 4) as f64 / 1.1) as usize,
                        }
                    })?
                }
            }
        };

        let oid = *self.object.id();
        let mut pointer = {
            let buffer = self.object.tail_mut();

            self.crypto.encrypt_chunk(
                match self.mode {
                    Mode::Data => Some(oid),
                    Mode::SealRoot(_) => None,
                },
                hash,
                &mut buffer[..size],
            )
        };

        pointer.file = oid;
        pointer.offs = self.object.position() as u32;
        *self.object.position_mut() += pointer.size as usize;

        Ok(pointer.into())
    }

    fn flush(&mut self) -> Result<()> {
        if let Mode::SealRoot(header_size) = self.mode {
            self.object
                .randomize_head(&self.crypto, header_size.try_into().unwrap());
        }
        self.object.finalize(&self.crypto);
        self.backend.write_object(&self.object)?;

        self.object.reset_id(&self.crypto);
        self.object.seek(match self.mode {
            Mode::SealRoot(header) => SeekFrom::Start(header),
            Mode::Data => SeekFrom::Start(0),
        })?;

        Ok(())
    }
}