update_package/
epoch.rs

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1// Copyright 2021 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5//! Typesafe wrappers around parsing the epoch.json file.
6
7use epoch::EpochFile;
8use fidl_fuchsia_io as fio;
9use thiserror::Error;
10use zx_status::Status;
11
12/// An error encountered while parsing the epoch.json file.
13#[derive(Debug, Error)]
14#[allow(missing_docs)]
15pub enum ParseEpochError {
16    #[error("while opening the file")]
17    OpenFile(#[source] fuchsia_fs::node::OpenError),
18
19    #[error("while reading the file")]
20    ReadFile(#[source] fuchsia_fs::file::ReadError),
21
22    #[error("while deserializing: `{0:?}`")]
23    Deserialize(String, #[source] serde_json::Error),
24}
25
26pub(crate) async fn epoch(proxy: &fio::DirectoryProxy) -> Result<Option<u64>, ParseEpochError> {
27    let file = match fuchsia_fs::directory::open_file(proxy, "epoch.json", fio::PERM_READABLE).await
28    {
29        Ok(file) => file,
30        Err(fuchsia_fs::node::OpenError::OpenError(Status::NOT_FOUND)) => return Ok(None),
31        Err(e) => return Err(ParseEpochError::OpenFile(e)),
32    };
33    let contents =
34        fuchsia_fs::file::read_to_string(&file).await.map_err(ParseEpochError::ReadFile)?;
35    match serde_json::from_str(&contents).map_err(|e| ParseEpochError::Deserialize(contents, e))? {
36        EpochFile::Version1 { epoch } => Ok(Some(epoch)),
37    }
38}
39
40#[cfg(test)]
41mod tests {
42    use super::*;
43    use crate::TestUpdatePackage;
44    use assert_matches::assert_matches;
45    use fuchsia_async as fasync;
46
47    #[fasync::run_singlethreaded(test)]
48    async fn parse_epoch_success() {
49        let p = TestUpdatePackage::new()
50            .add_file("epoch.json", serde_json::to_vec(&EpochFile::Version1 { epoch: 3 }).unwrap())
51            .await;
52        assert_matches!(p.epoch().await, Ok(Some(3)));
53    }
54
55    #[fasync::run_singlethreaded(test)]
56    async fn parse_epoch_success_missing_epoch_file() {
57        let p = TestUpdatePackage::new();
58        assert_matches!(p.epoch().await, Ok(None));
59    }
60
61    #[fasync::run_singlethreaded(test)]
62    async fn parse_epoch_fail_deserialize() {
63        let p = TestUpdatePackage::new().add_file("epoch.json", "oh no! this isn't json.").await;
64        assert_matches!(
65            p.epoch().await,
66            Err(ParseEpochError::Deserialize(s,_)) if s == "oh no! this isn't json."
67        );
68    }
69}
update_package/epoch.rs

update_package/
epoch.rs
