about summary refs log tree commit diff
path: root/tvix/store/src/nar/renderer.rs
blob: f510a9c76e60ea86a2ad2912d651f6ff45eb0977 (plain) (blame)
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
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
use super::RenderError;
use async_recursion::async_recursion;
use count_write::CountWrite;
use nix_compat::nar::writer::r#async as nar_writer;
use sha2::{Digest, Sha256};
use std::{
    pin::Pin,
    sync::Arc,
    task::{self, Poll},
};
use tokio::io::{self, AsyncWrite, BufReader};
use tokio_util::compat::{TokioAsyncReadCompatExt, TokioAsyncWriteCompatExt};
use tvix_castore::{
    blobservice::BlobService,
    directoryservice::DirectoryService,
    proto::{self as castorepb, NamedNode},
};

/// Invoke [write_nar], and return the size and sha256 digest of the produced
/// NAR output.
pub async fn calculate_size_and_sha256(
    root_node: &castorepb::node::Node,
    blob_service: Arc<dyn BlobService>,
    directory_service: Arc<dyn DirectoryService>,
) -> Result<(u64, [u8; 32]), RenderError> {
    let mut h = Sha256::new();
    let mut cw = CountWrite::from(&mut h);

    write_nar(
        // The hasher doesn't speak async. It doesn't
        // actually do any I/O, so it's fine to wrap.
        AsyncIoBridge(&mut cw),
        root_node,
        blob_service,
        directory_service,
    )
    .await?;

    Ok((cw.count(), h.finalize().into()))
}

/// The inverse of [tokio_util::io::SyncIoBridge].
/// Don't use this with anything that actually does blocking I/O.
struct AsyncIoBridge<T>(T);

impl<W: std::io::Write + Unpin> AsyncWrite for AsyncIoBridge<W> {
    fn poll_write(
        self: Pin<&mut Self>,
        _cx: &mut task::Context<'_>,
        buf: &[u8],
    ) -> Poll<io::Result<usize>> {
        Poll::Ready(self.get_mut().0.write(buf))
    }

    fn poll_flush(self: Pin<&mut Self>, _cx: &mut task::Context<'_>) -> Poll<io::Result<()>> {
        Poll::Ready(self.get_mut().0.flush())
    }

    fn poll_shutdown(
        self: Pin<&mut Self>,
        _cx: &mut task::Context<'_>,
    ) -> Poll<Result<(), io::Error>> {
        Poll::Ready(Ok(()))
    }
}

/// Accepts a [castorepb::node::Node] pointing to the root of a (store) path,
/// and uses the passed blob_service and directory_service to perform the
/// necessary lookups as it traverses the structure.
/// The contents in NAR serialization are writen to the passed [AsyncWrite].
pub async fn write_nar<W: AsyncWrite + Unpin + Send>(
    w: W,
    proto_root_node: &castorepb::node::Node,
    blob_service: Arc<dyn BlobService>,
    directory_service: Arc<dyn DirectoryService>,
) -> Result<(), RenderError> {
    // Initialize NAR writer
    let mut w = w.compat_write();
    let nar_root_node = nar_writer::open(&mut w)
        .await
        .map_err(RenderError::NARWriterError)?;

    walk_node(
        nar_root_node,
        proto_root_node,
        blob_service,
        directory_service,
    )
    .await?;

    Ok(())
}

/// Process an intermediate node in the structure.
/// This consumes the node.
#[async_recursion]
async fn walk_node(
    nar_node: nar_writer::Node<'async_recursion, '_>,
    proto_node: &castorepb::node::Node,
    blob_service: Arc<dyn BlobService>,
    directory_service: Arc<dyn DirectoryService>,
) -> Result<(), RenderError> {
    match proto_node {
        castorepb::node::Node::Symlink(proto_symlink_node) => {
            nar_node
                .symlink(&proto_symlink_node.target)
                .await
                .map_err(RenderError::NARWriterError)?;
        }
        castorepb::node::Node::File(proto_file_node) => {
            let digest_len = proto_file_node.digest.len();
            let digest = proto_file_node.digest.clone().try_into().map_err(|_| {
                RenderError::StoreError(io::Error::new(
                    io::ErrorKind::Other,
                    format!("invalid digest len {} in file node", digest_len),
                ))
            })?;

            let blob_reader = match blob_service
                .open_read(&digest)
                .await
                .map_err(RenderError::StoreError)?
            {
                Some(blob_reader) => Ok(BufReader::new(blob_reader)),
                None => Err(RenderError::NARWriterError(io::Error::new(
                    io::ErrorKind::NotFound,
                    format!("blob with digest {} not found", &digest),
                ))),
            }?;

            nar_node
                .file(
                    proto_file_node.executable,
                    proto_file_node.size,
                    &mut blob_reader.compat(),
                )
                .await
                .map_err(RenderError::NARWriterError)?;
        }
        castorepb::node::Node::Directory(proto_directory_node) => {
            let digest_len = proto_directory_node.digest.len();
            let digest = proto_directory_node
                .digest
                .clone()
                .try_into()
                .map_err(|_| {
                    RenderError::StoreError(io::Error::new(
                        io::ErrorKind::InvalidData,
                        format!("invalid digest len {} in directory node", digest_len),
                    ))
                })?;

            // look it up with the directory service
            match directory_service
                .get(&digest)
                .await
                .map_err(|e| RenderError::StoreError(e.into()))?
            {
                // if it's None, that's an error!
                None => {
                    return Err(RenderError::DirectoryNotFound(
                        digest,
                        proto_directory_node.name.clone(),
                    ))
                }
                Some(proto_directory) => {
                    // start a directory node
                    let mut nar_node_directory = nar_node
                        .directory()
                        .await
                        .map_err(RenderError::NARWriterError)?;

                    // for each node in the directory, create a new entry with its name,
                    // and then invoke walk_node on that entry.
                    for proto_node in proto_directory.nodes() {
                        let child_node = nar_node_directory
                            .entry(proto_node.get_name())
                            .await
                            .map_err(RenderError::NARWriterError)?;
                        walk_node(
                            child_node,
                            &proto_node,
                            blob_service.clone(),
                            directory_service.clone(),
                        )
                        .await?;
                    }

                    // close the directory
                    nar_node_directory
                        .close()
                        .await
                        .map_err(RenderError::NARWriterError)?;
                }
            }
        }
    }
    Ok(())
}