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// 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 std::ffi::CStr;
use std::future::Future;
use std::os::raw::c_char;
use std::pin::Pin;
use anyhow::Error;
use fuchsia_async::LocalExecutor;
use installer::{BootloaderType, InstallationPaths};
use recovery_util_block::BlockDevice;
use zx::Status;
// Converts a raw c-string into a Rust String, or None if the c-string was NULL.
//
// Making a String copies the data, but we do our work in a separate thread so we need a copy
// anyway to be able to move the string over.
fn to_string(c_str: *const c_char) -> Option<String> {
if c_str.is_null() {
return None;
}
// Safety: we've checked that the pointer is non-NULL and the C caller is required to meet the
// remaining safety requirements given by `install_from_usb()`.
unsafe { CStr::from_ptr(c_str) }.to_str().map(String::from).ok()
}
// Converts a Rust error to Zircon Status.
// We don't own anyhow::Error or Status so can't directly implement From<> or Into<>.
fn to_status(error: anyhow::Error) -> Status {
// We can't easily convert an arbitrary string into a meaningful Zircon error code, so
// we log the string for debugging and just report an internal error.
tracing::warn!("{error}");
Status::INTERNAL
}
// We can't currently auto-generate with `cbindgen` during build, so add lint checks as a reminder
// to re-generate the C bindings if this API changes. See README for details.
// LINT.IfChange
/// Installs images from a source disk to a destination disk.
///
/// This function can auto-detect the install source and destination if there is exactly one viable
/// candidate for each, otherwise they must be supplied by the caller.
///
/// # Arguments
/// `source`: UTF-8 source block device topological path, or NULL to auto-detect a removable disk.
/// `destination`: UTF-8 destination block device topological path, or NULL to auto-detect internal
/// storage.
///
/// # Returns
/// A zx_status code.
///
/// # Safety
/// The string arguments must either be NULL or meet all the conditions given at
/// https://doc.rust-lang.org/std/ffi/struct.CStr.html, primarily:
/// 1. The string must be null-terminated
/// 2. The contents must not be modified until this function returns
#[no_mangle]
pub extern "C" fn install_from_usb(source: *const c_char, destination: *const c_char) -> i32 {
// Include the function signature in the lint check, but not implementation, which can change
// without affecting the C bindings.
// LINT.ThenChange(../ffi_c/bindings.h)
// This function just handles C/Rust conversion and async execution so the internals can be pure
// async Rust.
tracing::trace!("Starting install_from_usb()");
// To handle async, this code spins up a separate thread with a new LocalExecutor. There may be
// a better way to do this, but these other methods failed:
// 1. New LocalExecutor on this thread - runtime panic, LocalExecutors are per-thread
// singletons and some components (in particular fastboot-tcp) may have already created
// one on this thread.
// 2. futures::executor::block_on() - runtime deadlock, this appears to be able to handle
// a single async call but the installer library runs concurrent async via
// futures::future::try_join_all() which deadlocks.
let source = to_string(source);
let destination = to_string(destination);
let func = move || {
LocalExecutor::new().run_singlethreaded(install_from_usb_internal(
source,
destination,
&Dependencies::default(),
))
};
let thread_result = std::thread::spawn(func).join();
tracing::trace!("install_from_usb() result = {thread_result:?}");
match thread_result {
Ok(result) => Status::from(result).into_raw(),
Err(thread_panic) => {
tracing::error!("install_from_usb thread panic: {thread_panic:?}");
Status::INTERNAL.into_raw()
}
}
}
// Dependency injection for testing.
//
// Unfortunately there doesn't seem to be a super easy way to do this:
// * mockall doesn't work well for free functions and has lifetime complications
// * traits can't define async functions so we can't have a trait wrapper
// So we just pass around a struct of function pointers, which due to `sync` requires some ugly
// pin/box boilerplate, lifetime management, and indirection.
//
// TODO: I think we can greatly simplify this by wrapping each function in a sync -> async
// wrapper individually. Maybe less efficient but we don't need the async functionality here
// and it would allow us to mock out sync functions instead which is far easier.
type BoxedFuture<'a, T> = Pin<Box<dyn Future<Output = T> + 'a>>;
struct Dependencies {
do_install: Box<dyn Fn(InstallationPaths) -> BoxedFuture<'static, Result<(), Error>>>,
find_install_source: Box<
dyn for<'a> Fn(
&'a Vec<BlockDevice>,
BootloaderType,
) -> BoxedFuture<'a, Result<&'a BlockDevice, Error>>,
>,
get_block_devices: Box<dyn Fn() -> BoxedFuture<'static, Result<Vec<BlockDevice>, Error>>>,
}
impl Dependencies {
// Returns the actual implementations.
fn default() -> Self {
Self {
// How do we pass the callback to `do_install()`? For now we don't need it so just pass
// a no-op closure, but I can't get the compiler to pass a real closure.
do_install: Box::new(move |a| Box::pin(installer::do_install(a, &|_| {}))),
find_install_source: Box::new(move |a, b| {
Box::pin(installer::find_install_source(a, b))
}),
get_block_devices: Box::new(move || Box::pin(recovery_util_block::get_block_devices())),
}
}
}
// Internal Rust entry point.
async fn install_from_usb_internal(
source: Option<String>,
destination: Option<String>,
dependencies: &Dependencies,
) -> Result<(), Status> {
tracing::trace!(
"Starting install_from_usb_internal(), source = {source:?}, dest = {destination:?}"
);
let installation_paths =
get_installation_paths(source.as_deref(), destination.as_deref(), dependencies).await?;
tracing::trace!("Installation paths: {installation_paths:?}");
(dependencies.do_install)(installation_paths).await.map_err(to_status)
}
// Finds the source and target to install.
async fn get_installation_paths(
requested_source: Option<&str>,
requested_destination: Option<&str>,
dependencies: &Dependencies,
) -> Result<InstallationPaths, Status> {
// The installer library hardcodes some rules about what partitions are expected on a disk
// depending on the bootloader (coreboot vs EFI). This is a bit brittle, we may want to look
// into removing this dependency in the future.
// For now we don't care about coreboot, just hardcode EFI.
let bootloader_type = BootloaderType::Efi;
tracing::trace!("Looking for block devices");
let block_devices = (dependencies.get_block_devices)().await.map_err(to_status)?;
tracing::trace!("Got block devices {block_devices:?}");
let install_source = match requested_source {
// If a particular block device was requested, use it (or error out if not found).
Some(device_path) => block_devices
.iter()
.find(|d| d.is_disk() && d.topo_path == device_path)
.ok_or(Err(Status::NOT_FOUND))?,
// Otherwise, try to auto-detect the removable disk (e.g. USB).
None => (dependencies.find_install_source)(&block_devices, bootloader_type)
.await
.map_err(to_status)?,
};
let install_filter = |d: &&BlockDevice| {
d.is_disk()
&& match requested_destination {
// If a particular block device was requested, use it.
Some(device_path) => d.topo_path == device_path,
// Otherwise use the disk that isn't our source.
None => *d != install_source,
}
};
let mut install_iter = block_devices.iter().filter(install_filter);
let install_target = install_iter.next().ok_or(Err(Status::NOT_FOUND))?;
// Don't install if there could have been multiple targets, since it's ambiguous which one
// the caller wants. They must provide a `requested_destination` in this case.
if install_iter.next().is_some() {
return Err(Status::INVALID_ARGS);
}
let paths = InstallationPaths {
install_source: Some(install_source.clone()),
install_target: Some(install_target.clone()),
bootloader_type: Some(bootloader_type),
// I don't think this is currently used - see if we can delete it.
install_destinations: Vec::new(),
available_disks: block_devices,
};
tracing::trace!("Found installation paths: {paths:?}");
Ok(paths)
}
#[cfg(test)]
mod tests {
use super::*;
use anyhow::anyhow;
use std::ffi::CString;
use std::ptr::null;
impl Dependencies {
// Returns the dependency test implementations.
fn test() -> Self {
Self {
do_install: Box::new(move |_| Box::pin(async { Ok(()) })),
find_install_source: Box::new(move |a, b| Box::pin(fake_find_install_source(a, b))),
get_block_devices: Box::new(move || Box::pin(fake_get_block_devices())),
}
}
// Returns the dependency test implementations that shows 3 disks.
fn test_3_disks() -> Self {
let mut deps = Self::test();
deps.get_block_devices = Box::new(move || Box::pin(fake_get_block_devices_3_disks()));
deps
}
}
// A fake set of block devices to test against.
async fn fake_get_block_devices() -> Result<Vec<BlockDevice>, Error> {
Ok(vec![
// 2 disks (disks do not contain "/block/part-" in topo_path).
BlockDevice {
topo_path: String::from("/dev/sys/platform/foo/block"),
class_path: String::from(""),
size: 0,
},
BlockDevice {
topo_path: String::from("/dev/sys/platform/bar/block"),
class_path: String::from(""),
size: 0,
},
// A handful of partitions on the disks.
BlockDevice {
topo_path: String::from("/dev/sys/platform/foo/block/part-000"),
class_path: String::from(""),
size: 0,
},
BlockDevice {
topo_path: String::from("/dev/sys/platform/foo/block/part-001"),
class_path: String::from(""),
size: 0,
},
BlockDevice {
topo_path: String::from("/dev/sys/platform/bar/block/part-000"),
class_path: String::from(""),
size: 0,
},
BlockDevice {
topo_path: String::from("/dev/sys/platform/bar/block/part-001"),
class_path: String::from(""),
size: 0,
},
])
}
// A fake set of block devices that contains more than 3 so we can't auto-detect the install
// target.
async fn fake_get_block_devices_3_disks() -> Result<Vec<BlockDevice>, Error> {
let mut devices = fake_get_block_devices().await.unwrap();
devices.append(&mut vec![
BlockDevice {
topo_path: String::from("/dev/sys/platform/baz/block"),
class_path: String::from(""),
size: 0,
},
BlockDevice {
topo_path: String::from("/dev/sys/platform/baz/block/part-000"),
class_path: String::from(""),
size: 0,
},
BlockDevice {
topo_path: String::from("/dev/sys/platform/baz/block/part-001"),
class_path: String::from(""),
size: 0,
},
]);
Ok(devices)
}
// Returns the first found block device. The real implementation checks to see if the disk has
// partitions with the expected installer GUID, but there's no point replicating that here.
async fn fake_find_install_source(
block_devices: &Vec<BlockDevice>,
_: BootloaderType,
) -> Result<&BlockDevice, Error> {
Ok(&block_devices[0])
}
#[fuchsia::test]
fn test_to_string() {
let c_string = CString::new("test string").unwrap();
assert_eq!(to_string(c_string.as_ptr()).unwrap(), "test string");
}
#[fuchsia::test]
fn test_to_string_null() {
assert!(to_string(null()).is_none());
}
#[fuchsia::test]
fn test_to_status() {
assert_eq!(to_status(anyhow!("expected test error")), Status::INTERNAL);
}
#[fuchsia_async::run_singlethreaded(test)]
async fn test_get_installation_paths() {
let deps = Dependencies::test();
let fake_devices = (deps.get_block_devices)().await.unwrap();
let paths = get_installation_paths(None, None, &deps).await.unwrap();
assert_eq!(
paths,
InstallationPaths {
install_source: Some(fake_devices[0].clone()),
// Target should be the non-source disk.
install_target: Some(fake_devices[1].clone()),
bootloader_type: Some(BootloaderType::Efi),
install_destinations: Vec::new(),
available_disks: fake_devices,
}
);
}
#[fuchsia_async::run_singlethreaded(test)]
async fn test_get_installation_paths_request_source() {
let deps = Dependencies::test();
let fake_devices = (deps.get_block_devices)().await.unwrap();
// Request the 2nd disk as the install source.
let paths =
get_installation_paths(Some(&fake_devices[1].topo_path), None, &deps).await.unwrap();
assert_eq!(
paths,
InstallationPaths {
install_source: Some(fake_devices[1].clone()),
install_target: Some(fake_devices[0].clone()),
bootloader_type: Some(BootloaderType::Efi),
install_destinations: Vec::new(),
available_disks: fake_devices,
}
);
}
#[fuchsia_async::run_singlethreaded(test)]
async fn test_get_installation_paths_request_target() {
let deps = Dependencies::test();
let fake_devices = (deps.get_block_devices)().await.unwrap();
// Request the 2nd disk as the install target.
let paths =
get_installation_paths(None, Some(&fake_devices[1].topo_path), &deps).await.unwrap();
assert_eq!(
paths,
InstallationPaths {
install_source: Some(fake_devices[0].clone()),
install_target: Some(fake_devices[1].clone()),
bootloader_type: Some(BootloaderType::Efi),
install_destinations: Vec::new(),
available_disks: fake_devices,
}
);
}
#[fuchsia_async::run_singlethreaded(test)]
async fn test_get_installation_paths_request_both() {
let deps = Dependencies::test_3_disks();
let fake_devices = (deps.get_block_devices)().await.unwrap();
let paths = get_installation_paths(
Some(&fake_devices[1].topo_path),
// device[6] is the 3rd disk "baz" in our fake disks list.
Some(&fake_devices[6].topo_path),
&deps,
)
.await
.unwrap();
assert_eq!(
paths,
InstallationPaths {
install_source: Some(fake_devices[1].clone()),
install_target: Some(fake_devices[6].clone()),
bootloader_type: Some(BootloaderType::Efi),
install_destinations: Vec::new(),
available_disks: fake_devices,
}
);
}
#[fuchsia_async::run_singlethreaded(test)]
async fn test_get_installation_paths_ambiguous_target() {
let deps = Dependencies::test_3_disks();
let fake_devices = (deps.get_block_devices)().await.unwrap();
// With 3 disks we should error out because we can't determine which target to use.
assert_eq!(
get_installation_paths(Some(&fake_devices[0].topo_path), None, &deps,).await,
Err(Status::INVALID_ARGS)
);
}
#[fuchsia_async::run_singlethreaded(test)]
async fn test_install_from_usb() {
let deps = Dependencies::test();
assert!(install_from_usb_internal(None, None, &deps).await.is_ok());
}
#[fuchsia::test]
fn test_install_from_usb_fail_sync() {
// Test the top-level API in a sync context.
// We expect it to fail, this is primarily to ensure our async calls work.
let source = CString::new("foo").unwrap();
let dest = CString::new("bar").unwrap();
assert!(install_from_usb(source.as_ptr(), dest.as_ptr()) != Status::OK.into_raw());
}
#[fuchsia::test]
async fn test_install_from_usb_fail_async() {
// Test the top-level API in an async context.
// We expect it to fail, this is primarily to ensure our async calls work.
let source = CString::new("foo").unwrap();
let dest = CString::new("bar").unwrap();
assert!(install_from_usb(source.as_ptr(), dest.as_ptr()) != Status::OK.into_raw());
}
}