src/devices/bin/driver_host2/driver_host.cc

// Copyright 2020 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.

#include "src/devices/bin/driver_host2/driver_host.h"

#include <fuchsia/io/llcpp/fidl.h>
#include <lib/async-loop/loop.h>
#include <lib/fdio/directory.h>
#include <zircon/dlfcn.h>

#include <fs/service.h>

#include "src/devices/lib/driver2/start_args.h"
#include "src/devices/lib/log/log.h"

namespace fdf = llcpp::fuchsia::driver::framework;
namespace fio = llcpp::fuchsia::io;
namespace frunner = llcpp::fuchsia::component::runner;

zx::status<std::unique_ptr<Driver>> Driver::Load(zx::vmo vmo) {
  void* library = dlopen_vmo(vmo.get(), RTLD_NOW);
  if (library == nullptr) {
    LOGF(ERROR, "Failed to start driver, could not load library: %s", dlerror());
    return zx::error(ZX_ERR_INTERNAL);
  }
  auto record = static_cast<DriverRecordV1*>(dlsym(library, "__fuchsia_driver_record__"));
  if (record == nullptr) {
    LOGF(ERROR, "Failed to start driver, driver record not found");
    return zx::error(ZX_ERR_NOT_FOUND);
  }
  if (record->version != 1) {
    LOGF(ERROR, "Failed to start driver, unknown driver record version: %lu", record->version);
    return zx::error(ZX_ERR_WRONG_TYPE);
  }
  return zx::ok(std::make_unique<Driver>(library, record));
}

Driver::Driver(void* library, DriverRecordV1* record) : library_(library), record_(record) {}

Driver::~Driver() {
  zx_status_t status = record_->stop(opaque_);
  if (status != ZX_OK) {
    LOGF(ERROR, "Failed to stop driver: %s", zx_status_get_string(status));
  }
  dlclose(library_);

  if (binding_.has_value()) {
    binding_->Unbind();
  }
}

void Driver::set_binding(
    fidl::ServerBindingRef<llcpp::fuchsia::driver::framework::Driver> binding) {
  binding_ = std::make_optional(std::move(binding));
}

zx::status<> Driver::Start(const fidl::OutgoingMessage& message, async_dispatcher_t* dispatcher) {
  zx_handle_info_t handle_infos[ZX_CHANNEL_MAX_MSG_HANDLES];
  fidl_incoming_msg_t msg;
  zx_status_t status = fidl::OutgoingToIncomingMessage(message.message(), handle_infos,
                                                       ZX_CHANNEL_MAX_MSG_HANDLES, &msg);
  if (status != ZX_OK) {
    return zx::make_status(status);
  }
  record_->start(&msg, dispatcher, &opaque_);
  return zx::make_status(status);
}

DriverHost::DriverHost(async::Loop* loop) : loop_(loop) {}

zx::status<> DriverHost::PublishDriverHost(const fbl::RefPtr<fs::PseudoDir>& svc_dir) {
  const auto service = [this](zx::channel request) {
    auto result = fidl::BindServer(loop_->dispatcher(), std::move(request), this);
    if (result.is_error()) {
      LOGF(ERROR, "Failed to bind channel to '%s': %s", fdf::DriverHost::Name,
           zx_status_get_string(result.error()));
      return result.error();
    }
    return ZX_OK;
  };
  zx_status_t status =
      svc_dir->AddEntry(fdf::DriverHost::Name, fbl::MakeRefCounted<fs::Service>(service));
  if (status != ZX_OK) {
    LOGF(ERROR, "Failed to add directory entry '%s': %s", fdf::DriverHost::Name,
         zx_status_get_string(status));
  }
  return zx::make_status(status);
}

void DriverHost::Start(fdf::DriverStartArgs start_args, zx::channel request,
                       StartCompleter::Sync& completer) {
  auto pkg = start_args.has_ns() ? start_args::ns_value(start_args.ns(), "/pkg")
                                 : zx::error(ZX_ERR_INVALID_ARGS);
  if (pkg.is_error()) {
    LOGF(ERROR, "Failed to start driver, missing '/pkg' directory: %s",
         zx_status_get_string(pkg.error_value()));
    completer.Close(pkg.error_value());
    return;
  }
  auto binary = start_args.has_program() ? start_args::program_value(start_args.program(), "binary")
                                         : zx::error(ZX_ERR_INVALID_ARGS);
  if (binary.is_error()) {
    LOGF(ERROR, "Failed to start driver, missing 'binary' argument: %s",
         zx_status_get_string(binary.error_value()));
    completer.Close(binary.error_value());
    return;
  }
  // Open the driver's binary within the driver's package.
  zx::channel client_end, server_end;
  zx_status_t status = zx::channel::create(0, &client_end, &server_end);
  if (status != ZX_OK) {
    completer.Close(status);
    return;
  }
  status =
      fdio_open_at(pkg->get(), binary->data(),
                   fio::OPEN_RIGHT_READABLE | fio::OPEN_RIGHT_EXECUTABLE, server_end.release());
  if (status != ZX_OK) {
    LOGF(ERROR, "Failed to start driver '/pkg/%s', could not open library: %s", binary->data(),
         zx_status_get_string(status));
    completer.Close(status);
    return;
  }
  // We encode start_args outside of callback in order to access stack-allocated
  // data before it is destroyed.
  auto message = std::make_unique<fdf::DriverStartArgs::OwnedEncodedMessage>(&start_args);
  if (!message->ok()) {
    LOGF(ERROR, "Failed to start driver '/pkg/%s', could not encode start args: %s", binary->data(),
         message->error());
    completer.Close(message->status());
    return;
  }
  // Once we receive the VMO from the call to GetBuffer, we can load the driver
  // into this driver host. We move the storage and encoded for start_args into
  // this callback to extend its lifetime.
  fidl::Client<fio::File> file(
      std::move(client_end), loop_->dispatcher(), [binary = binary.value()](fidl::UnbindInfo info) {
        if (info.status != ZX_OK) {
          LOGF(ERROR, "Failed to start driver '/pkg/%s', could not open library: %s", binary.data(),
               zx_status_get_string(info.status));
        }
      });
  auto file_ptr = file.get();
  auto callback = [this, request = std::move(request), completer = completer.ToAsync(),
                   binary = std::move(binary.value()), message = std::move(message),
                   file = std::move(file)](fio::File::GetBufferResponse* response) mutable {
    if (response->s != ZX_OK) {
      LOGF(ERROR, "Failed to start driver '/pkg/%s', could not get library VMO: %s", binary.data(),
           zx_status_get_string(response->s));
      completer.Close(response->s);
      return;
    }
    zx_status_t status =
        response->buffer->vmo.set_property(ZX_PROP_NAME, binary.data(), binary.size());
    if (status != ZX_OK) {
      LOGF(ERROR, "Failed to start driver '/pkg/%s', could not name library VMO: %s", binary.data(),
           zx_status_get_string(status));
      completer.Close(status);
      return;
    }
    auto driver = Driver::Load(std::move(response->buffer->vmo));
    if (driver.is_error()) {
      completer.Close(driver.error_value());
      return;
    }
    auto driver_ptr = driver.value().get();
    auto bind = fidl::BindServer<Driver>(loop_->dispatcher(), std::move(request), driver_ptr,
                                         [this](Driver* driver, auto, auto) {
                                           drivers_.erase(*driver);
                                           // If this is the last driver, shutdown the driver host.
                                           if (drivers_.is_empty()) {
                                             loop_->Quit();
                                           }
                                         });
    if (bind.is_error()) {
      LOGF(ERROR,
           "Failed to start driver '/pkg/%s', could not bind channel to "
           "'fuchsia.driver.framework.DriverHost': %s",
           binary.data(), zx_status_get_string(bind.error()));
      completer.Close(bind.error());
      return;
    }
    driver->set_binding(bind.take_value());
    drivers_.push_back(std::move(driver.value()));

    auto start = driver_ptr->Start(message->GetOutgoingMessage(), loop_->dispatcher());
    if (start.is_error()) {
      LOGF(ERROR, "Failed to start driver '/pkg/%s': %s", binary.data(), start.status_string());
      completer.Close(start.error_value());
      return;
    }
    // After the driver successfully starts, we assume it has taken ownership of
    // the handles from |start_args|, and can therefore relinquish ownership.
    message->GetOutgoingMessage().ReleaseHandles();
    LOGF(INFO, "Started '%s'", binary.data());
  };
  file_ptr->GetBuffer(fio::VMO_FLAG_READ | fio::VMO_FLAG_EXEC | fio::VMO_FLAG_PRIVATE,
                      std::move(callback));
}