zircon/system/ulib/service/llcpp/service.cc

// 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.

#include <fuchsia/io/llcpp/fidl.h>
#include <lib/fdio/directory.h>
#include <lib/fidl/llcpp/array.h>
#include <lib/fidl/llcpp/connect_service.h>
#include <lib/fit/result.h>
#include <lib/service/llcpp/service.h>
#include <zircon/device/vfs.h>

namespace service {

::zx::status<::fidl::ClientEnd<fuchsia_io::Directory>> OpenServiceRoot(const char* path) {
  return ::service::Connect<fuchsia_io::Directory>(path);
}

namespace internal {

::zx::status<zx::channel> ConnectRaw(const char* path) {
  ::zx::channel client_end, server_end;
  if (zx_status_t status = ::zx::channel::create(0, &client_end, &server_end); status != ZX_OK) {
    return ::zx::error(status);
  }
  if (zx_status_t status = fdio_service_connect(path, server_end.release()); status != ZX_OK) {
    return ::zx::error(status);
  }
  return ::zx::ok(std::move(client_end));
}

::zx::status<zx::channel> ConnectAtRaw(::fidl::UnownedClientEnd<fuchsia_io::Directory> svc_dir,
                                       const char* protocol_name) {
  ::zx::channel client_end, server_end;
  if (zx_status_t status = ::zx::channel::create(0, &client_end, &server_end); status != ZX_OK) {
    return ::zx::error(status);
  }
  if (zx_status_t status =
          fdio_service_connect_at(svc_dir.handle(), protocol_name, server_end.release());
      status != ZX_OK) {
    return ::zx::error(status);
  }
  return ::zx::ok(std::move(client_end));
}

::zx::status<::zx::channel> CloneRaw(::zx::unowned_channel&& node) {
  ::zx::channel client_end, server_end;
  zx_status_t status = ::zx::channel::create(0, &client_end, &server_end);
  if (status != ZX_OK) {
    return ::zx::error(status);
  }
  status = fdio_service_clone_to(node->get(), server_end.release());
  if (status != ZX_OK) {
    return ::zx::error(status);
  }
  return ::zx::ok(std::move(client_end));
}

}  // namespace internal

}  // namespace service

namespace llcpp::sys {

namespace {

constexpr uint64_t kMaxFilename = fuchsia_io::wire::MAX_FILENAME;

// Max path length will be two path components, separated by a file separator.
constexpr uint64_t kMaxPath = (2 * kMaxFilename) + 1;

::zx::status<::fidl::StringView> ValidateAndJoinPath(::fidl::Array<char, kMaxPath>* buffer,
                                                     ::fidl::StringView service,
                                                     ::fidl::StringView instance) {
  if (service.empty() || service.size() > kMaxFilename) {
    return ::zx::error(ZX_ERR_INVALID_ARGS);
  }
  if (instance.size() > kMaxFilename) {
    return ::zx::error(ZX_ERR_INVALID_ARGS);
  }
  if (service[0] == '/') {
    return ::zx::error(ZX_ERR_INVALID_ARGS);
  }

  const uint64_t path_size = service.size() + instance.size() + 1;
  ZX_ASSERT(path_size <= kMaxPath);

  char* path_cursor = buffer->data();
  memcpy(path_cursor, service.data(), service.size());
  path_cursor += service.size();
  *path_cursor++ = '/';
  memcpy(path_cursor, instance.data(), instance.size());
  return ::zx::ok(::fidl::StringView::FromExternal(buffer->data(), path_size));
}

}  // namespace

namespace internal {

::zx::status<> DirectoryOpenFunc(::zx::unowned_channel dir, ::fidl::StringView path,
                                 ::zx::channel remote) {
  constexpr uint32_t flags =
      fuchsia_io::wire::OPEN_RIGHT_READABLE | fuchsia_io::wire::OPEN_RIGHT_WRITABLE;
  fidl::WireResult<fuchsia_io::Directory::Open> result =
      fidl::WireCall<fuchsia_io::Directory>(dir).Open(flags, uint32_t(0755), std::move(path),
                                                      std::move(remote));
  return ::zx::make_status(result.status());
}

}  // namespace internal

::zx::status<> OpenNamedServiceAt(::fidl::UnownedClientEnd<fuchsia_io::Directory> dir,
                                  cpp17::string_view service, cpp17::string_view instance,
                                  ::zx::channel remote) {
  ::fidl::Array<char, kMaxPath> path_buffer;
  ::zx::status<::fidl::StringView> path_result =
      ValidateAndJoinPath(&path_buffer, ::fidl::StringView::FromExternal(service),
                          ::fidl::StringView::FromExternal(instance));
  if (!path_result.is_ok()) {
    return path_result.take_error();
  }
  return internal::DirectoryOpenFunc(dir.channel(), std::move(path_result.value()),
                                     std::move(remote));
}

}  // namespace llcpp::sys