src/sys/pkg/lib/fuchsia-pkg-testing/src/package.rs

// Copyright 2019 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.

//! Test tools for building Fuchsia packages.

use anyhow::{Context as _, Error, format_err};
use blobfs_ramdisk::BlobfsRamdisk;
use camino::{Utf8Path, Utf8PathBuf};
use fidl_fuchsia_io as fio;
use fuchsia_merkle::Hash;
use fuchsia_pkg::{MetaContents, MetaSubpackages, PackageManifest};
use fuchsia_url::PackageName;
use fuchsia_url::fuchsia_pkg::PinnedAbsolutePackageUrl;
use futures::join;
use futures::prelude::*;
use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};
use std::convert::TryInto as _;
use std::fs::{self, File};
use std::io::{self, Read};
use std::path::{Path, PathBuf};
use tempfile::TempDir;
use version_history::AbiRevision;
use walkdir::WalkDir;
use zx::Status;

/// A package generated by a [`PackageBuilder`], suitable for assembling into a TUF repository.
#[derive(Debug)]
pub struct Package {
    name: PackageName,
    meta_far_merkle: Hash,
    _artifacts_tmp: TempDir,
    artifacts: Utf8PathBuf,
    // If None then the package has subpackages but this `Package` does not have all the blobs
    // needed by those subpackages.
    subpackage_blobs: Option<HashMap<Hash, Vec<u8>>>,
}

#[derive(Debug, PartialEq)]
enum PackageEntry {
    Directory,
    File(Vec<u8>),
}

impl PackageEntry {
    fn is_dir(&self) -> bool {
        matches!(self, PackageEntry::Directory)
    }
}
pub struct BlobFile {
    pub merkle: fuchsia_merkle::Hash,
    pub file: File,
}

/// Contents of a Blob.
pub struct BlobContents {
    /// Merkle hash of the blob.
    pub merkle: fuchsia_merkle::Hash,

    /// Binary contents of the blob.
    pub contents: Vec<u8>,
}

impl Package {
    /// The merkle root of the package's meta.far.
    pub fn hash(&self) -> &Hash {
        &self.meta_far_merkle
    }

    /// The package's meta.far.
    pub fn meta_far(&self) -> io::Result<File> {
        File::open(self.artifacts.join("meta.far"))
    }

    /// The name of the package.
    pub fn name(&self) -> &PackageName {
        &self.name
    }

    /// The pinned fuchsia-pkg url of the package on fuchsia.com.
    pub fn pinned_fuchsia_url(&self) -> PinnedAbsolutePackageUrl {
        let unpinned = format!("fuchsia-pkg://fuchsia.com/{}", self.name).parse().unwrap();
        PinnedAbsolutePackageUrl::from_unpinned(unpinned, self.meta_far_merkle)
    }

    /// The directory containing the blobs contained in the package, including the meta.far.
    pub fn artifacts(&self) -> &Utf8Path {
        &self.artifacts
    }

    /// Builds and returns the package located at "/pkg" in the current namespace.
    pub async fn identity() -> Result<Self, Error> {
        Self::from_dir("/pkg").await
    }

    /// Builds and returns the package located at the given path in the current namespace.
    pub async fn from_dir(root: impl AsRef<Path>) -> Result<Self, Error> {
        let root = root.as_ref();
        let package_directory = fuchsia_pkg::PackageDirectory::from_proxy(
            fuchsia_fs::directory::open_in_namespace(root.to_str().unwrap(), fio::PERM_READABLE)?,
        );

        let meta_package = package_directory.meta_package().await.context("read meta/package")?;
        let abi_revision = package_directory.abi_revision().await.context("read abi revision")?;

        let mut pkg =
            PackageBuilder::new_with_abi_revision(meta_package.name().as_ref(), abi_revision);

        fn is_generated_file(path: &Path) -> bool {
            matches!(
                path.to_str(),
                Some("meta/contents")
                    | Some("meta/package")
                    | Some(AbiRevision::PATH)
                    | Some(MetaSubpackages::PATH)
            )
        }

        // Add all non-generated files from this package into `pkg`.
        for entry in WalkDir::new(root) {
            let entry = entry?;
            let path = entry.path();
            if !entry.file_type().is_file() || is_generated_file(path.strip_prefix(root).unwrap()) {
                continue;
            }

            let relative_path = path.strip_prefix(root).unwrap();
            let f = File::open(path).context("open package blob")?;
            pkg = pkg.add_resource_at(relative_path.to_str().unwrap(), f);
        }

        let subpackages = package_directory
            .meta_subpackages()
            .await
            .context("read meta subpackages")?
            .into_subpackages();
        if !subpackages.is_empty() {
            for (name, hash) in subpackages.into_iter() {
                pkg = pkg.add_subpackage_by_hash(name, hash);
            }
        }

        pkg.build().await
    }

    /// Returns the parsed contents of the meta/contents file.
    pub fn meta_contents(&self) -> Result<MetaContents, Error> {
        let mut raw_meta_far = self.meta_far()?;
        let mut meta_far = fuchsia_archive::Utf8Reader::new(&mut raw_meta_far)?;
        let raw_meta_contents = meta_far.read_file("meta/contents")?;

        Ok(MetaContents::deserialize(raw_meta_contents.as_slice())?)
    }

    /// Returns the parsed contents of the subpackages manifest.
    pub fn meta_subpackages(&self) -> Result<MetaSubpackages, Error> {
        let mut raw_meta_far = self.meta_far()?;
        let mut meta_far = fuchsia_archive::Utf8Reader::new(&mut raw_meta_far)?;
        Ok(match meta_far.read_file(MetaSubpackages::PATH) {
            Ok(bytes) => MetaSubpackages::deserialize(std::io::BufReader::new(bytes.as_slice()))?,
            Err(fuchsia_archive::Error::PathNotPresent(_)) => MetaSubpackages::default(),
            Err(e) => Err(e)?,
        })
    }

    /// Returns a set of all unique blobs contained in this package, including meta.far and
    /// subpackage blobs.
    ///
    /// # Panics
    /// If either there are unknown subpackage blobs or there is an error reading meta/contents.
    pub fn list_blobs(&self) -> BTreeSet<Hash> {
        self.meta_contents()
            .expect("loading meta/contents")
            .into_hashes_undeduplicated()
            .chain([self.meta_far_merkle])
            .chain(
                self.subpackage_blobs
                    .as_ref()
                    .unwrap_or_else(|| {
                        panic!(
                            "cannot list blobs for package {} with unknown subpackage blobs",
                            self.name()
                        )
                    })
                    .keys()
                    .copied(),
            )
            .collect()
    }

    /// Returns an iterator of merkle/File pairs for each content blob in the package.
    ///
    /// Does not include the meta.far, see `meta_far()` and `meta_far_merkle_root()`, instead.
    pub fn content_blob_files(&self) -> impl Iterator<Item = BlobFile> {
        let manifest =
            fuchsia_pkg::PackageManifest::try_load_from(self.artifacts().join("manifest.json"))
                .unwrap();
        struct Blob {
            merkle: fuchsia_merkle::Hash,
            path: Utf8PathBuf,
        }
        #[allow(clippy::needless_collect)]
        let blobs = manifest
            .into_blobs()
            .into_iter()
            .filter(|blob| blob.path != PackageManifest::META_FAR_BLOB_PATH)
            .map(|blob| Blob {
                merkle: blob.merkle,
                path: self.artifacts().join(&blob.source_path),
            })
            .collect::<Vec<_>>();

        blobs
            .into_iter()
            .map(|blob| BlobFile { merkle: blob.merkle, file: File::open(blob.path).unwrap() })
    }

    /// Returns a tuple of the contents of the meta far and the contents of all content blobs in the package.
    pub fn contents(&self) -> (BlobContents, HashMap<Hash, Vec<u8>>) {
        (
            BlobContents {
                merkle: self.meta_far_merkle,
                contents: io::BufReader::new(self.meta_far().unwrap())
                    .bytes()
                    .collect::<Result<Vec<u8>, _>>()
                    .unwrap(),
            },
            self.content_blob_files()
                .map(|blob_file| {
                    (
                        blob_file.merkle,
                        io::BufReader::new(blob_file.file)
                            .bytes()
                            .collect::<Result<Vec<u8>, _>>()
                            .unwrap(),
                    )
                })
                .collect(),
        )
    }

    /// Returns None if this `Package` has subpackages but doesn't have the blobs.
    pub fn content_and_subpackage_blobs(&self) -> Option<HashMap<Hash, Vec<u8>>> {
        if let Some(subpackage_blobs) = &self.subpackage_blobs {
            let mut subpackage_blobs = subpackage_blobs.clone();
            subpackage_blobs.extend(self.content_blob_files().map(|blob_file| {
                (
                    blob_file.merkle,
                    io::BufReader::new(blob_file.file)
                        .bytes()
                        .collect::<Result<Vec<u8>, _>>()
                        .unwrap(),
                )
            }));
            Some(subpackage_blobs)
        } else {
            None
        }
    }

    /// Writes the meta.far and all content blobs to blobfs.
    /// Does not write the subpackage blobs, if any.
    pub async fn write_to_blobfs_ignore_subpackages(&self, blobfs_ramdisk: &BlobfsRamdisk) {
        fn read_file(file: &std::fs::File) -> Vec<u8> {
            let mut ret = vec![];
            std::io::BufReader::new(file).read_to_end(&mut ret).unwrap();
            ret
        }

        blobfs_ramdisk
            .write_blob(*self.hash(), &read_file(&self.meta_far().unwrap()))
            .await
            .expect("write_blob failed");
        for blob in self.content_blob_files() {
            blobfs_ramdisk
                .write_blob(blob.merkle, &read_file(&blob.file))
                .await
                .expect("write_blob failed");
        }
    }

    /// Writes the meta.far and all content and subpackage blobs to blobfs.
    pub async fn write_to_blobfs(&self, blobfs_ramdisk: &BlobfsRamdisk) {
        let subpackage_blobs = self
            .subpackage_blobs
            .as_ref()
            .expect("package must know the subpackage blobs to write them");
        let () = self.write_to_blobfs_ignore_subpackages(blobfs_ramdisk).await;
        for (hash, content) in subpackage_blobs {
            blobfs_ramdisk.write_blob(*hash, content).await.expect("write_blob failed");
        }
    }

    /// Verifies that the given directory serves the contents of this package.
    pub async fn verify_contents(
        &self,
        dir: &fio::DirectoryProxy,
    ) -> Result<(), VerificationError> {
        let mut raw_meta_far = self.meta_far()?;
        let mut meta_far = fuchsia_archive::Utf8Reader::new(&mut raw_meta_far)?;
        let mut expected_paths = HashSet::new();

        // Verify all entries referenced by meta/contents exist and have the correct merkle root.
        let raw_meta_contents = meta_far.read_file("meta/contents")?;
        let meta_contents = MetaContents::deserialize(raw_meta_contents.as_slice())?;
        for (path, merkle) in meta_contents.contents() {
            let actual_merkle = fuchsia_merkle::root_from_slice(read_file(dir, path).await?);
            if merkle != &actual_merkle {
                return Err(VerificationError::DifferentFileData { path: path.to_owned() });
            }
            expected_paths.insert(path.to_owned());
        }

        // Verify all entries in the meta FAR exist and have the correct contents.
        for path in meta_far.list().map(|e| e.path().to_string()).collect::<Vec<_>>() {
            if read_file(dir, path.as_str()).await? != meta_far.read_file(path.as_str())? {
                return Err(VerificationError::DifferentFileData { path });
            }
            expected_paths.insert(path);
        }

        // Verify no other entries exist in the served directory.
        let mut stream = fuchsia_fs::directory::readdir_recursive(dir, /*timeout=*/ None);
        while let Some(entry) = stream.try_next().await? {
            let path = entry.name;
            if !expected_paths.contains(path.as_str()) {
                return Err(VerificationError::ExtraFile { path });
            }
        }

        Ok(())
    }

    /// The blobs used by all of the subpackages of this package (recursively).
    /// If None, this `Package` has subpackages but does not have the blobs needed by those
    /// subpackages.
    pub fn subpackage_blobs(&self) -> Option<&HashMap<Hash, Vec<u8>>> {
        self.subpackage_blobs.as_ref()
    }
}

async fn read_file(dir: &fio::DirectoryProxy, path: &str) -> Result<Vec<u8>, VerificationError> {
    let (file, server_end) = fidl::endpoints::create_proxy::<fio::FileMarker>();

    let flags = fio::Flags::FLAG_SEND_REPRESENTATION | fio::PERM_READABLE;
    dir.open(path, flags, &fio::Options::default(), server_end.into_channel())
        .expect("open3 request failed to send");

    let mut events = file.take_event_stream();
    let open = async move {
        let event = match events.next().await.expect("Some(event)") {
            Ok(representation) => match representation {
                fio::FileEvent::OnOpen_ { s, info } => {
                    match Status::ok(s) {
                        Err(Status::NOT_FOUND) => {
                            Err(VerificationError::MissingFile { path: path.to_owned() })
                        }
                        Err(status) => {
                            Err(format_err!("unable to open {:?}: {:?}", path, status).into())
                        }
                        Ok(()) => Ok(()),
                    }?;

                    match *info.expect("fio::FileEvent to have fio::NodeInfoDeprecated") {
                        fio::NodeInfoDeprecated::File(fio::FileObject { event, .. }) => event,
                        other => {
                            panic!(
                                "fio::NodeInfoDeprecated from fio::FileEventStream to be File variant with event: {other:?}"
                            )
                        }
                    }
                }
                fio::FileEvent::OnRepresentation { payload } => match payload {
                    fio::Representation::File(fio::FileInfo { observer, .. }) => observer,
                    other => {
                        panic!(
                            "ConnectionInfo from fio::FileEventStream to be File variant with event: {other:?}"
                        )
                    }
                },
                fio::FileEvent::_UnknownEvent { ordinal, .. } => {
                    panic!("unknown file event {ordinal}")
                }
            },
            // If not found, Open3 will send an epitaph when closing the channel.
            Err(fidl::Error::ClientChannelClosed { epitaph, .. })
                if epitaph == zx::Status::NOT_FOUND =>
            {
                return Err(VerificationError::MissingFile { path: path.to_owned() });
            }
            Err(other_e) => {
                return Err(
                    format_err!("open fidl request at {:?} failed: {:?}", path, other_e).into()
                );
            }
        };

        // Files served by the package will either provide an event in its describe info (if that
        // file is actually a blob from blobfs) or not provide an event (if that file is, for
        // example, a file contained within the meta far being served in the meta/ directory).
        //
        // If the file is a blobfs blob, we want to make sure it is readable. We can just try to
        // read from it, but the preferred method to wait for a blobfs blob to become readable is
        // to wait on the USER_0 signal to become asserted on the file's event.
        //
        // As all blobs served by a package should already be readable, we assert that USER_0 is
        // already asserted on the event.
        if let Some(event) = event {
            match event
                .wait_one(
                    zx::Signals::USER_0,
                    zx::MonotonicInstant::after(zx::MonotonicDuration::from_seconds(0)),
                )
                .to_result()
            {
                Err(Status::TIMED_OUT) => Err(VerificationError::from(format_err!(
                    "file served by blobfs is not complete/readable as USER_0 signal was not set on the File's event: {}",
                    path
                ))),
                Err(other_status) => Err(VerificationError::from(format_err!(
                    "wait_handle failed with status: {:?} {:?}",
                    other_status,
                    path
                ))),
                Ok(_) => Ok(()),
            }
        } else {
            Ok(())
        }
    };

    let read = async {
        let result =
            file.get_backing_memory(fio::VmoFlags::READ).await?.map_err(Status::err_from_raw);

        let mut expect_empty_blob = false;

        // Attempt to get the backing VMO, which is faster. Fall back to reading over FIDL
        match result {
            Ok(vmo) => {
                let size = vmo.get_content_size().context("unable to get vmo size")?;
                let mut buf = vec![0u8; size as usize];
                let () = vmo.read(&mut buf[..], 0).context("unable to read from vmo")?;
                return Ok(buf);
            }
            Err(status) => match status {
                Status::NOT_SUPPORTED => {}
                Status::BAD_STATE => {
                    // may or may not be intended behavior, but the empty blob will not provide a vmo,
                    // failing with BAD_STATE. Verify in the read path below that the blob is indeed
                    // zero length if this happens.
                    expect_empty_blob = true;
                }
                status => {
                    return Err(VerificationError::from(format_err!(
                        "unexpected error opening file buffer: {:?}",
                        status
                    )));
                }
            },
        }

        let mut buf = vec![];
        loop {
            let chunk = file
                .read(fio::MAX_BUF)
                .await
                .context("file read to respond")?
                .map_err(Status::err_from_raw)
                .map_err(|status| VerificationError::FileReadError { path: path.into(), status })?;

            if chunk.is_empty() {
                if expect_empty_blob {
                    assert_eq!(buf, Vec::<u8>::new());
                }
                return Ok(buf);
            }

            buf.extend(chunk);
        }
    };

    let (open, read) = join!(open, read);
    let close_result = file.close().await;
    let result = open.and(read)?;
    // Only check close_result if everything that came before it looks good.
    let close_result = close_result.context("file close to respond")?;
    close_result.map_err(|status| {
        format_err!("unable to close {:?}: {:?}", path, zx::Status::err_from_raw(status))
    })?;
    Ok(result)
}

/// An error that can occur while verifying the contents of a directory.
#[derive(Debug)]
pub enum VerificationError {
    /// The directory is serving a file that isn't in the package.
    ExtraFile {
        /// Path to the extra file.
        path: String,
    },
    /// The directory is not serving a particular file that it should be serving.
    MissingFile {
        /// Path to the missing file.
        path: String,
    },
    /// The actual merkle of the file does not match the merkle listed in the meta FAR.
    DifferentFileData {
        /// Path to the file.
        path: String,
    },
    /// Read method on file failed.
    FileReadError {
        /// Path to the file
        path: String,
        /// Read result
        status: Status,
    },
    /// Anything else.
    Other(Error),
}

impl<T: Into<Error>> From<T> for VerificationError {
    fn from(x: T) -> Self {
        VerificationError::Other(x.into())
    }
}

/// A builder to simplify construction of Fuchsia packages.
pub struct PackageBuilder {
    name: PackageName,
    contents: BTreeMap<PathBuf, PackageEntry>,

    has_subpackages: bool,
    // If None the package has subpackages but this `PackageBuilder` does not have the blobs
    // needed by those subpackages.
    subpackage_blobs: Option<HashMap<Hash, Vec<u8>>>,

    builder: fuchsia_pkg::PackageBuilder,
    _artifacts_tmp: TempDir,
    artifacts: Utf8PathBuf,
}

impl PackageBuilder {
    /// Creates a new `PackageBuilder`.
    ///
    /// # Panics
    ///
    /// Panics if either:
    /// * `name` is an invalid package name.
    /// * Creating a tempdir fails.
    pub fn new(name: impl Into<String>) -> Self {
        Self::new_with_abi_revision(
            name,
            // Default to ABI revision for API level 7.
            0xECCEA2F70ACD6FC0.into(),
        )
    }

    /// Creates a new `PackageBuilder`, just like `PackageBuilder::new()`, but
    /// allowing the caller to specify the ABI revision with which to stamp the
    /// test package.
    pub fn new_with_abi_revision(name: impl Into<String>, abi_revision: AbiRevision) -> Self {
        let name = name.into();

        let artifacts_tmp = tempfile::tempdir().expect("create tempdir for package");
        let artifacts = Utf8Path::from_path(artifacts_tmp.path())
            .expect("checking packagedir is UTF-8")
            .to_path_buf();

        fs::create_dir(artifacts.join("contents")).expect("create /packages/contents");

        let mut builder = fuchsia_pkg::PackageBuilder::new(&name, abi_revision);
        builder.manifest_path(artifacts.join("manifest.json"));
        builder.repository("fuchsia.com");
        builder.manifest_blobs_relative_to(fuchsia_pkg::RelativeTo::File);

        Self {
            builder,
            name: name.try_into().unwrap(),
            contents: BTreeMap::new(),
            has_subpackages: false,
            subpackage_blobs: Some(HashMap::new()),
            _artifacts_tmp: artifacts_tmp,
            artifacts,
        }
    }

    /// Create a subdirectory within the package.
    ///
    /// # Panics
    ///
    /// Panics if the package contains a file entry at `path` or any of its ancestors.
    pub fn dir(mut self, path: impl Into<PathBuf>) -> PackageDir {
        let path = path.into();
        self.make_dirs(&path);
        PackageDir::new(self, path)
    }

    /// Adds the provided `contents` to the package at the given `path`.
    ///
    /// # Panics
    ///
    /// Panics if either:
    /// * The package already contains a file or directory at `path`.
    /// * The package contains a file at any of `path`'s ancestors.
    pub fn add_resource_at(
        mut self,
        path: impl Into<PathBuf>,
        mut contents: impl io::Read,
    ) -> Self {
        let path = path.into();
        let path_str = path.to_str().unwrap();
        let () = fuchsia_url::Resource::validate_str(
            path.to_str().unwrap_or_else(|| panic!("path must be utf8: {path:?}")),
        )
        .unwrap_or_else(|_| panic!("path must be an object relative path expression: {path:?}"));

        let mut data = vec![];
        contents.read_to_end(&mut data).unwrap();

        if path.starts_with("meta/") {
            self.builder
                .add_contents_to_far(path_str, &data, self.artifacts.join("contents"))
                .expect("adding meta blob to succeed");
        } else {
            self.builder
                .add_contents_as_blob(path_str, &data, self.artifacts.join("contents"))
                .expect("adding blob to succeed");
        }

        let replaced = self.contents.insert(path.clone(), PackageEntry::File(data));
        assert_eq!(None, replaced, "already contains an entry at {path:?}");
        self
    }

    fn make_dirs(&mut self, path: &Path) {
        for ancestor in path.ancestors() {
            if ancestor == Path::new("") {
                continue;
            }
            assert!(
                self.contents
                    .entry(ancestor.to_owned())
                    .or_insert(PackageEntry::Directory)
                    .is_dir(),
                "{ancestor:?} is not a directory"
            );
        }
    }

    /// Adds the provided `subpackage` to the package with name `name`.
    ///
    /// # Panics
    ///
    /// Panics if either:
    /// * `name` is not a valid RelativePackageUrl
    /// * There is already a subpackage called `name`
    pub fn add_subpackage(
        mut self,
        name: impl TryInto<fuchsia_url::RelativePackageUrl>,
        subpackage: &Package,
    ) -> Self {
        let name = name.try_into().map_err(|_| ()).expect("valid RelativePackageUrl");
        let manifest_path = subpackage.artifacts().join("manifest.json").into();

        self.builder.add_subpackage(&name, *subpackage.hash(), manifest_path).unwrap();
        self.has_subpackages = true;

        match (&mut self.subpackage_blobs, &subpackage.subpackage_blobs) {
            (Some(current_blobs), Some(new_blobs)) => {
                let (meta_far, content_blobs) = subpackage.contents();
                current_blobs.insert(meta_far.merkle, meta_far.contents);
                current_blobs.extend(content_blobs);
                current_blobs.extend(new_blobs.iter().map(|(k, v)| (*k, v.clone())));
            }
            (Some(_), None) => self.subpackage_blobs = None,
            (None, Some(_)) | (None, None) => {}
        }

        self
    }

    /// Adds a subpackage with name `name` and hash `hash` to the package.
    /// Because the blobs of the subpackage are not provided, the `Package` built from this
    /// `PackageBuilder` will not have the subpackage blobs.
    ///
    /// # Panics
    ///
    /// Panics if either:
    /// * `name` is not a valid RelativePackageUrl
    /// * There is already a subpackage called `name`
    pub fn add_subpackage_by_hash(
        mut self,
        name: impl TryInto<fuchsia_url::RelativePackageUrl>,
        hash: Hash,
    ) -> Self {
        let name = name.try_into().map_err(|_| ()).expect("valid RelativePackageUrl");

        self.builder.add_subpackage(&name, hash, "".into()).unwrap();
        self.has_subpackages = true;
        self.subpackage_blobs = None;
        self
    }

    /// Builds the package.
    pub async fn build(self) -> Result<Package, Error> {
        // self.artifacts contains outputs from package creation (manifest.json/meta.far) as well
        // as all blobs contained in the package.
        //
        // Layout of self.artifacts:
        // - manifest.json
        // - meta.far
        // - contents/
        // -   meta/
        // -     non-generated meta.far files
        // -   file/dir{N}

        let manifest = self.builder.build(&self.artifacts, self.artifacts.join("meta.far"))?;
        let meta_far_merkle =
            manifest.blobs().iter().find(|b| b.path == "meta/").context("finding meta/")?.merkle;

        // clean up after ourselves
        fs::remove_file(self.artifacts.join("meta/fuchsia.abi/abi-revision"))?;
        fs::remove_dir(self.artifacts.join("meta/fuchsia.abi"))?;
        if self.has_subpackages {
            fs::remove_file(self.artifacts.join("meta/fuchsia.pkg/subpackages"))?;
            fs::remove_dir(self.artifacts.join("meta/fuchsia.pkg"))?;
        }
        fs::remove_file(self.artifacts.join("meta/package"))?;
        fs::remove_dir(self.artifacts.join("meta"))?;

        Ok(Package {
            name: self.name,
            meta_far_merkle,
            _artifacts_tmp: self._artifacts_tmp,
            artifacts: self.artifacts,
            subpackage_blobs: self.subpackage_blobs,
        })
    }
}

/// A subdirectory of a package being built.
pub struct PackageDir {
    pkg: PackageBuilder,
    path: PathBuf,
}

impl PackageDir {
    fn new(pkg: PackageBuilder, path: impl Into<PathBuf>) -> Self {
        Self { pkg, path: path.into() }
    }

    /// Adds the provided `contents` to the package at the given `path`, relative to this
    /// `PackageDir`.
    ///
    /// # Panics
    /// If the package already contains a resource at `path`, relative to this `PackageDir`.
    pub fn add_resource_at(mut self, path: impl AsRef<Path>, contents: impl io::Read) -> Self {
        self.pkg = self.pkg.add_resource_at(self.path.join(path.as_ref()), contents);
        self
    }

    /// Finish adding resources to this directory, returning the modified [`PackageBuilder`].
    pub fn finish(self) -> PackageBuilder {
        self.pkg
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use assert_matches::assert_matches;
    use fuchsia_pkg::MetaPackage;

    #[test]
    #[should_panic(expected = "adding blob to succeed")]
    fn test_panics_file_with_existing_parent_as_file() {
        let _: Result<(), Error> = {
            PackageBuilder::new("test")
                .add_resource_at("data", "data contents".as_bytes())
                .add_resource_at("data/foo", "data/foo contents".as_bytes());
            Ok(())
        };
    }

    #[test]
    #[should_panic(expected = r#""data" is not a directory"#)]
    fn test_panics_dir_with_existing_file() {
        let _: Result<(), Error> = {
            PackageBuilder::new("test")
                .add_resource_at("data", "data contents".as_bytes())
                .dir("data");
            Ok(())
        };
    }

    #[test]
    #[should_panic(expected = r#""data" is not a directory"#)]
    fn test_panics_nested_dir_with_existing_file() {
        let _: Result<(), Error> = {
            PackageBuilder::new("test")
                .add_resource_at("data", "data contents".as_bytes())
                .dir("data/foo");
            Ok(())
        };
    }

    #[test]
    #[should_panic(expected = "adding blob to succeed")]
    fn test_panics_file_with_existing_dir() {
        let _: Result<(), Error> = {
            PackageBuilder::new("test")
                .dir("data")
                .add_resource_at("foo", "data/foo contents".as_bytes())
                .finish()
                .add_resource_at("data", "data contents".as_bytes());
            Ok(())
        };
    }

    #[fuchsia::test]
    async fn test_basic() -> Result<(), Error> {
        let pkg = PackageBuilder::new("rolldice")
            .dir("bin")
            .add_resource_at("rolldice", "asldkfjaslkdfjalskdjfalskdf".as_bytes())
            .finish()
            .build()
            .await?;

        assert_eq!(
            pkg.meta_far_merkle,
            "de210ba39b8f597cc1986c37b369c990707649f63bb8fa23b244a38274018b78".parse()?
        );
        assert_eq!(pkg.meta_far_merkle, fuchsia_merkle::root_from_reader(pkg.meta_far()?)?);
        assert_eq!(
            pkg.list_blobs(),
            BTreeSet::from([
                "de210ba39b8f597cc1986c37b369c990707649f63bb8fa23b244a38274018b78".parse()?,
                "b5b34f6234631edc7ccaa25533e2050e5d597a7331c8974306b617a3682a3197".parse()?
            ])
        );

        Ok(())
    }

    #[fuchsia::test]
    async fn test_content_blob_files() -> Result<(), Error> {
        let pkg = PackageBuilder::new("rolldice")
            .dir("bin")
            .add_resource_at("rolldice", "asldkfjaslkdfjalskdjfalskdf".as_bytes())
            .add_resource_at("rolldice2", "asldkfjaslkdfjalskdjfalskdf".as_bytes())
            .finish()
            .build()
            .await?;

        let mut iter = pkg.content_blob_files();
        // 2 identical entries
        for _ in 0..2 {
            let BlobFile { merkle, mut file } = iter.next().unwrap();
            assert_eq!(
                merkle,
                "b5b34f6234631edc7ccaa25533e2050e5d597a7331c8974306b617a3682a3197".parse().unwrap()
            );
            let mut contents = vec![];
            file.read_to_end(&mut contents).unwrap();
            assert_eq!(contents, b"asldkfjaslkdfjalskdjfalskdf")
        }
        assert_eq!(iter.next().map(|b| b.merkle), None);

        Ok(())
    }

    #[fuchsia::test]
    async fn test_dir_semantics() -> Result<(), Error> {
        let with_dir = PackageBuilder::new("data-file")
            .dir("data")
            .add_resource_at("file", "contents".as_bytes())
            .finish()
            .build()
            .await?;

        let with_direct = PackageBuilder::new("data-file")
            .add_resource_at("data/file", "contents".as_bytes())
            .build()
            .await?;

        assert_eq!(with_dir.hash(), with_direct.hash());

        Ok(())
    }

    /// Creates a clone of the contents of /pkg in a tempdir so that tests can manipulate its
    /// contents.
    fn make_this_package_dir() -> Result<tempfile::TempDir, Error> {
        let dir = tempfile::tempdir()?;

        let this_package_root = Path::new("/pkg");

        for entry in WalkDir::new(this_package_root) {
            let entry = entry?;
            let path = entry.path();

            let relative_path = path.strip_prefix(this_package_root).unwrap();
            let rebased_path = dir.path().join(relative_path);

            if entry.file_type().is_dir() {
                fs::create_dir_all(rebased_path)?;
            } else if entry.file_type().is_file() {
                fs::copy(path, rebased_path)?;
            }
        }

        Ok(dir)
    }

    #[fuchsia::test]
    async fn test_from_dir() {
        let abi_revision = AbiRevision::from_u64(0x5836508c2defac54); // Random value.

        let root = {
            let dir = tempfile::tempdir().unwrap();

            fs::create_dir(dir.path().join("meta")).unwrap();
            fs::create_dir(dir.path().join("data")).unwrap();

            MetaPackage::from_name_and_variant_zero("asdf".parse().unwrap())
                .serialize(File::create(dir.path().join("meta/package")).unwrap())
                .unwrap();

            fs::create_dir(dir.path().join("meta/fuchsia.abi")).unwrap();
            fs::write(dir.path().join("meta/fuchsia.abi/abi-revision"), abi_revision.as_bytes())
                .unwrap();

            fs::write(dir.path().join("data/hello"), "world").unwrap();

            dir
        };

        let from_dir = Package::from_dir(root.path()).await.unwrap();

        let pkg = PackageBuilder::new_with_abi_revision("asdf", abi_revision)
            .add_resource_at("data/hello", "world".as_bytes())
            .build()
            .await
            .unwrap();

        assert_eq!(from_dir.meta_far_merkle, pkg.meta_far_merkle);
    }

    #[fuchsia::test]
    async fn test_identity() -> Result<(), Error> {
        let pkg = Package::identity().await.unwrap();

        assert_eq!(pkg.meta_far_merkle, fuchsia_merkle::root_from_reader(pkg.meta_far()?)?);

        // Verify the generated package's merkle root is the same as this test package's merkle root.
        assert_eq!(pkg.meta_far_merkle, fs::read_to_string("/pkg/meta")?.parse()?);

        let this_pkg_dir = fuchsia_fs::directory::open_in_namespace("/pkg", fio::PERM_READABLE)?;
        pkg.verify_contents(&this_pkg_dir).await.expect("contents to be equivalent");

        let pkg_dir = make_this_package_dir()?;

        let this_pkg_dir = fuchsia_fs::directory::open_in_namespace(
            pkg_dir.path().to_str().unwrap(),
            fio::PERM_READABLE,
        )?;

        assert_matches!(pkg.verify_contents(&this_pkg_dir).await, Ok(()));

        Ok(())
    }

    #[fuchsia::test]
    async fn test_verify_contents_rejects_extra_blob() -> Result<(), Error> {
        let pkg = Package::identity().await?;
        let pkg_dir = make_this_package_dir()?;

        fs::write(pkg_dir.path().join("unexpected"), "unexpected file".as_bytes())?;

        let pkg_dir_proxy = fuchsia_fs::directory::open_in_namespace(
            pkg_dir.path().to_str().unwrap(),
            fio::PERM_READABLE,
        )?;

        assert_matches!(
            pkg.verify_contents(&pkg_dir_proxy).await,
            Err(VerificationError::ExtraFile{ref path}) if path == "unexpected");

        Ok(())
    }

    #[fuchsia::test]
    async fn test_verify_contents_rejects_extra_meta_file() -> Result<(), Error> {
        let pkg = Package::identity().await?;
        let pkg_dir = make_this_package_dir()?;

        fs::write(pkg_dir.path().join("meta/unexpected"), "unexpected file".as_bytes())?;

        let pkg_dir_proxy = fuchsia_fs::directory::open_in_namespace(
            pkg_dir.path().to_str().unwrap(),
            fio::PERM_READABLE,
        )?;

        assert_matches!(
            pkg.verify_contents(&pkg_dir_proxy).await,
            Err(VerificationError::ExtraFile{ref path}) if path == "meta/unexpected");

        Ok(())
    }

    #[fuchsia::test]
    async fn test_verify_contents_rejects_missing_blob() -> Result<(), Error> {
        let pkg = Package::identity().await?;
        let pkg_dir = make_this_package_dir()?;

        fs::remove_file(pkg_dir.path().join("bin/fuchsia_pkg_testing_lib_test"))?;

        let pkg_dir_proxy = fuchsia_fs::directory::open_in_namespace(
            pkg_dir.path().to_str().unwrap(),
            fio::PERM_READABLE,
        )?;

        assert_matches!(
            pkg.verify_contents(&pkg_dir_proxy).await,
            Err(VerificationError::MissingFile{ref path}) if path == "bin/fuchsia_pkg_testing_lib_test");

        Ok(())
    }

    #[fuchsia::test]
    async fn test_verify_contents_rejects_different_contents() -> Result<(), Error> {
        let pkg = Package::identity().await?;
        let pkg_dir = make_this_package_dir()?;

        fs::write(pkg_dir.path().join("bin/fuchsia_pkg_testing_lib_test"), "broken".as_bytes())?;

        let pkg_dir_proxy = fuchsia_fs::directory::open_in_namespace(
            pkg_dir.path().to_str().unwrap(),
            fio::PERM_READABLE,
        )?;

        assert_matches!(
            pkg.verify_contents(&pkg_dir_proxy).await,
            Err(VerificationError::DifferentFileData{ref path}) if path == "bin/fuchsia_pkg_testing_lib_test");

        Ok(())
    }

    #[fuchsia::test]
    async fn test_meta_subpackages_with_no_subpackages() {
        let pkg = PackageBuilder::new("pkg").build().await.unwrap();

        assert!(pkg.meta_subpackages().unwrap().subpackages().is_empty());
    }

    #[fuchsia::test]
    async fn test_add_subpackage() {
        // Package with subpackage.
        let sub_sub_pkg = PackageBuilder::new("sub-sub-pkg")
            .add_resource_at("c-blob", "c-blob-contents".as_bytes())
            .build()
            .await
            .unwrap();

        let sub_pkg = PackageBuilder::new("sub-pkg")
            .add_resource_at("b-blob", "b-blob-contents".as_bytes())
            .add_subpackage("subpackage-1", &sub_sub_pkg)
            .build()
            .await
            .unwrap();

        let mut expected_subpackage_blobs = HashMap::new();
        let (sub_sub_pkg_meta_far, content_blobs) = sub_sub_pkg.contents();
        expected_subpackage_blobs
            .insert(sub_sub_pkg_meta_far.merkle, sub_sub_pkg_meta_far.contents);
        expected_subpackage_blobs
            .insert(content_blobs.into_keys().next().unwrap(), b"c-blob-contents".to_vec());

        assert_eq!(*sub_pkg.subpackage_blobs().unwrap(), expected_subpackage_blobs);
        assert_eq!(
            sub_pkg.meta_subpackages().unwrap(),
            MetaSubpackages::from_iter([(
                fuchsia_url::RelativePackageUrl::parse("subpackage-1").unwrap(),
                sub_sub_pkg_meta_far.merkle
            )])
        );
        let (sub_pkg_meta_far, content_blobs) = sub_pkg.contents();
        let mut expected_all_blobs = content_blobs
            .keys()
            .copied()
            .chain([sub_pkg_meta_far.merkle])
            .chain(expected_subpackage_blobs.keys().copied())
            .collect();
        assert_eq!(sub_pkg.list_blobs(), expected_all_blobs);

        // Package with subpackage that is a superpackage.
        let pkg = PackageBuilder::new("pkg")
            .add_subpackage("subpackage-0", &sub_pkg)
            .build()
            .await
            .unwrap();

        expected_subpackage_blobs.insert(sub_pkg_meta_far.merkle, sub_pkg_meta_far.contents);
        expected_subpackage_blobs
            .insert(content_blobs.into_keys().next().unwrap(), b"b-blob-contents".to_vec());

        assert_eq!(*pkg.subpackage_blobs().unwrap(), expected_subpackage_blobs);
        assert_eq!(
            pkg.meta_subpackages().unwrap(),
            MetaSubpackages::from_iter([(
                fuchsia_url::RelativePackageUrl::parse("subpackage-0").unwrap(),
                sub_pkg_meta_far.merkle
            )])
        );
        expected_all_blobs.insert(*pkg.hash());
        assert_eq!(pkg.list_blobs(), expected_all_blobs);
    }

    #[fuchsia::test]
    async fn test_add_subpackage_by_hash() {
        let pkg = PackageBuilder::new("pkg")
            .add_subpackage_by_hash("subpackage-name", Hash::from([0; 32]))
            .build()
            .await
            .unwrap();

        assert_eq!(pkg.subpackage_blobs(), None);
        assert_eq!(
            pkg.meta_subpackages().unwrap(),
            MetaSubpackages::from_iter([(
                fuchsia_url::RelativePackageUrl::parse("subpackage-name").unwrap(),
                Hash::from([0; 32])
            )])
        );
    }
}