src/storage/ext4/lib/ext4_extract/src/lib.rs

// Copyright 2023 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

use crate::remote_bundle::{Owner, Writer};

use {
    anyhow::{Context, Error, Result},
    ext4_metadata::{ExtendedAttributes, ROOT_INODE_NUM},
    ext4_read_only::{
        parser::Parser as ExtParser,
        readers::{IoAdapter, Reader},
        structs::{DirEntry2, EntryType},
    },
    sparse::reader::SparseReader,
    std::{collections::HashMap, io::Cursor},
};

pub mod remote_bundle;

pub(crate) const METADATA_PATH: &str = "metadata.v1";

/// Extract the files from an ext4 image at `path` and return a map of the destination
/// to source pairs. Additionally, create a metadata file that provides information
/// necessary for mounting the files from a fuchsia package.
pub fn ext4_extract(path: &str, out_dir: &str) -> Result<HashMap<String, String>, Error> {
    let mut file =
        std::fs::File::open(path).with_context(|| format!("Unable to open `{:?}'", path))?;
    let reader = if sparse::is_sparse_image(&mut file) {
        Box::new(IoAdapter::new(SparseReader::new(Box::new(file))?)) as Box<dyn Reader>
    } else {
        Box::new(IoAdapter::new(file)) as Box<dyn Reader>
    };
    let parser = ExtParser::new(reader);

    let inode = parser.inode(ROOT_INODE_NUM as u32).unwrap();
    let mut writer = Writer::new(
        &out_dir,
        ROOT_INODE_NUM,
        inode.e2di_mode.get(),
        Owner::from_inode(&inode),
        ExtendedAttributes::new(),
    )?;

    parser.index(
        parser.root_inode()?,
        vec![],
        &mut |parser: &ExtParser, path: Vec<&str>, entry: &DirEntry2| {
            let xattr: ExtendedAttributes = parser
                .inode_xattrs(entry.e2d_ino.get())?
                .into_iter()
                .map(|(k, v)| (k.into(), v.into()))
                .collect();

            let inode_num = entry.e2d_ino.get();
            let inode = parser.inode(inode_num).unwrap();
            let mode = inode.e2di_mode.get();
            let owner = Owner::from_inode(&inode);

            match EntryType::from_u8(entry.e2d_type)? {
                EntryType::RegularFile => {
                    let data = parser.read_data(inode_num)?;
                    let mut cursor = Cursor::new(data);
                    writer
                        .add_file(&path, &mut cursor, inode_num as u64, mode, owner, xattr)
                        .unwrap();
                }
                EntryType::SymLink => {
                    let data = parser.read_data(inode_num)?;
                    writer.add_symlink(&path, data, inode_num as u64, mode, owner, xattr).unwrap();
                }
                EntryType::Directory => {
                    writer.add_directory(&path, inode_num as u64, mode, owner, xattr);
                }
                _ => {}
            }
            Ok(true)
        },
    )?;

    Ok(writer.export()?)
}