ext4_parser/
lib.rs

1// Copyright 2019 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
5use ext4_read_only::parser::Parser;
6use ext4_read_only::readers::{BlockDeviceReader, Reader, VmoReader};
7use ext4_read_only::structs::{self, MIN_EXT4_SIZE};
8use fidl::endpoints::ClientEnd;
9use fidl_fuchsia_hardware_block::BlockMarker;
10use log::error;
11use std::sync::Arc;
12
13pub enum FsSourceType {
14    BlockDevice(ClientEnd<BlockMarker>),
15    Vmo(zx::Vmo),
16}
17
18#[derive(Debug, PartialEq)]
19pub enum ConstructFsError {
20    VmoReadError(zx::Status),
21    ParsingError(structs::ParsingError),
22}
23
24pub fn construct_fs(
25    source: FsSourceType,
26) -> Result<Arc<vfs::directory::immutable::Simple>, ConstructFsError> {
27    let reader: Box<dyn Reader> = match source {
28        FsSourceType::BlockDevice(block_device) => {
29            Box::new(BlockDeviceReader::from_client_end(block_device).map_err(|e| {
30                error!("Error constructing file system: {}", e);
31                ConstructFsError::VmoReadError(zx::Status::IO_INVALID)
32            })?)
33        }
34        FsSourceType::Vmo(vmo) => {
35            let size = vmo.get_size().map_err(ConstructFsError::VmoReadError)?;
36            if size < MIN_EXT4_SIZE as u64 {
37                // Too small to even fit the first copy of the ext4 Super Block.
38                return Err(ConstructFsError::VmoReadError(zx::Status::NO_SPACE));
39            }
40
41            Box::new(VmoReader::new(Arc::new(vmo)))
42        }
43    };
44
45    let parser = Parser::new(reader);
46
47    match parser.build_fuchsia_tree() {
48        Ok(tree) => Ok(tree),
49        Err(e) => Err(ConstructFsError::ParsingError(e)),
50    }
51}
52
53#[cfg(test)]
54mod tests {
55    use super::{construct_fs, FsSourceType};
56
57    use ext4_read_only::structs::MIN_EXT4_SIZE;
58    use fidl_fuchsia_io as fio;
59    use fuchsia_fs::directory::{open_file, readdir, DirEntry, DirentKind};
60    use fuchsia_fs::file::read_to_string;
61    use std::fs;
62    use zx::Vmo;
63
64    #[fuchsia::test]
65    fn image_too_small() {
66        let vmo = Vmo::create(10).expect("VMO is created");
67        vmo.write(b"too small", 0).expect("VMO write() succeeds");
68        let buffer = FsSourceType::Vmo(vmo);
69
70        assert!(construct_fs(buffer).is_err(), "Expected failed parsing of VMO.");
71    }
72
73    #[fuchsia::test]
74    fn invalid_fs() {
75        let vmo = Vmo::create(MIN_EXT4_SIZE as u64).expect("VMO is created");
76        vmo.write(b"not ext4", 0).expect("VMO write() succeeds");
77        let buffer = FsSourceType::Vmo(vmo);
78
79        assert!(construct_fs(buffer).is_err(), "Expected failed parsing of VMO.");
80    }
81
82    #[fuchsia::test]
83    async fn list_root() {
84        let data = fs::read("/pkg/data/nest.img").expect("Unable to read file");
85        let vmo = Vmo::create(data.len() as u64).expect("VMO is created");
86        vmo.write(data.as_slice(), 0).expect("VMO write() succeeds");
87        let buffer = FsSourceType::Vmo(vmo);
88
89        let tree = construct_fs(buffer).expect("construct_fs parses the vmo");
90        let root = vfs::directory::serve(tree, fio::PERM_READABLE);
91
92        let expected = vec![
93            DirEntry { name: String::from("file1"), kind: DirentKind::File },
94            DirEntry { name: String::from("inner"), kind: DirentKind::Directory },
95            DirEntry { name: String::from("lost+found"), kind: DirentKind::Directory },
96        ];
97        assert_eq!(readdir(&root).await.unwrap(), expected);
98
99        let file = open_file(&root, "file1", fio::PERM_READABLE).await.unwrap();
100        assert_eq!(read_to_string(&file).await.unwrap(), "file1 contents.\n");
101        file.close().await.unwrap().map_err(zx::Status::from_raw).unwrap();
102        root.close().await.unwrap().map_err(zx::Status::from_raw).unwrap();
103    }
104}
ext4_parser/lib.rs

ext4_parser/
lib.rs
