sdk/lib/zxio/private.h

// Copyright 2016 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.

#ifndef LIB_ZXIO_PRIVATE_H_
#define LIB_ZXIO_PRIVATE_H_

#include <fidl/fuchsia.hardware.pty/cpp/wire.h>
#include <fidl/fuchsia.io/cpp/wire.h>
#include <fidl/fuchsia.posix.socket.packet/cpp/wire.h>
#include <fidl/fuchsia.posix.socket.raw/cpp/wire.h>
#include <fidl/fuchsia.posix.socket/cpp/wire.h>
#include <fidl/fuchsia.unknown/cpp/wire.h>
#include <lib/zx/channel.h>
#include <lib/zx/debuglog.h>
#include <lib/zx/event.h>
#include <lib/zxio/ops.h>
#include <lib/zxio/zxio.h>
#include <zircon/availability.h>
#include <zircon/types.h>

// A utility which helps implementing the C-style |zxio_ops_t| ops table
// from a C++ class. The specific backend implementation should inherit
// from |HasIo| as the first base class, ensuring that the |zxio_t| part
// appears that the beginning of its object layout.
class HasIo {
 protected:
  explicit HasIo(const zxio_ops_t& ops) { zxio_init(&io_, &ops); }

  zxio_t* io() { return &io_; }
  const zxio_t* io() const { return &io_; }

  template <typename T>
  struct Adaptor {
    static_assert(std::is_base_of<HasIo, T>::value);
    static_assert(sizeof(T) <= sizeof(zxio_storage_t),
                  "C++ implementation class must fit inside zxio_storage_t.");
    static_assert(!std::is_polymorphic_v<T>, "C++ implementation class must not contain vtables.");

    // Converts a member function in the implementation C++ class to a signature
    // compatible with the definition in the ops table.
    //
    // This class assumes the |zxio_t*| pointer as passed as the first argument to
    // all |zxio_ops_t| entries is the pointer to the C++ implementation instance.
    //
    // For example, given the |release| call with the following signature:
    //
    //   zx_status_t (*release)(zxio_t* io, zx_handle_t* out_handle);
    //
    // The C++ implementation may define a member function with this signature:
    //
    //   zx_status_t MyClass::Release(zx_handle_t* out_handle);
    //
    // And |Adaptor<MyClass>::From<&Release>| will evaluate to a function with a
    // signature compatible to the C-style definition, treating |io| as a pointer
    // to the |HasIo|, invoking the corresponding member function automatically.
    template <auto fn, typename... Args>
    static auto From(zxio_t* io, Args... args) {
      T& instance = *reinterpret_cast<T*>(io);
      return (instance.*fn)(args...);
    }
  };

 private:
  static constexpr void CheckLayout();

  zxio_t io_;
};

constexpr void HasIo::CheckLayout() {
  static_assert(offsetof(HasIo, io_) == 0);
  static_assert(alignof(HasIo) == alignof(zxio_t));
}

// Implementation of |zxio_ops_t::readv| for a channel that speaks fuchsia.io/Readable.
zx_status_t RemoteReadv(const fidl::UnownedClientEnd<fuchsia_io::Readable>& client_end,
                        const zx_iovec_t* vector, size_t vector_count, zxio_flags_t flags,
                        size_t* out_actual);

// Implementation of |zxio_ops_t::writev| for a channel that speaks fuchsia.io/Writable.
zx_status_t RemoteWritev(const fidl::UnownedClientEnd<fuchsia_io::Writable>& client_end,
                         const zx_iovec_t* vector, size_t vector_count, zxio_flags_t flags,
                         size_t* out_actual);

bool zxio_is_valid(const zxio_t* io);

zx_status_t zxio_dir_init(zxio_storage_t* storage, fidl::ClientEnd<fuchsia_io::Directory> client);

zx_status_t zxio_file_init(zxio_storage_t* storage, zx::event event, zx::stream stream,
                           fidl::ClientEnd<fuchsia_io::File> client);

zx_status_t zxio_node_init(zxio_storage_t* storage, fidl::ClientEnd<fuchsia_io::Node> client);

zx_status_t zxio_pty_init(zxio_storage_t* storage, zx::eventpair event,
                          fidl::ClientEnd<fuchsia_hardware_pty::Device> client);

zx_status_t zxio_pipe_init(zxio_storage_t* pipe, zx::socket socket, zx_info_socket_t info);

zx_status_t zxio_symlink_init(zxio_storage_t* storage, fidl::ClientEnd<fuchsia_io::Symlink> client,
                              std::vector<uint8_t> target);

zx_status_t zxio_attr_from_wire(const fuchsia_io::wire::NodeAttributes2& in,
                                zxio_node_attributes_t* out);

// debuglog --------------------------------------------------------------------

// Initializes a |zxio_storage_t| to use the given |handle| for output.
//
// The |handle| should be a Zircon debuglog object.
zx_status_t zxio_debuglog_init(zxio_storage_t* storage, zx::debuglog handle);

// pipe ------------------------------------------------------------------------

// A |zxio_t| backend that uses a Zircon socket object.
//
// The |socket| handle is a Zircon socket object.
//
// Will eventually be an implementation detail of zxio once fdio completes its
// transition to the zxio backend.
using zxio_pipe_t = struct zxio_pipe {
  zxio_t io;
  zx::socket socket;
};

static_assert(sizeof(zxio_pipe_t) <= sizeof(zxio_storage_t),
              "zxio_pipe_t must fit inside zxio_storage_t.");

// synchronous datagram socket (channel backed) --------------------------------------------

zx_status_t zxio_synchronous_datagram_socket_init(
    zxio_storage_t* storage, zx::eventpair event,
    fidl::ClientEnd<fuchsia_posix_socket::SynchronousDatagramSocket> client);

// datagram socket (channel backed)

zx_status_t zxio_datagram_socket_init(zxio_storage_t* storage, zx::socket socket,
                                      const zx_info_socket_t& info,
                                      const zxio_datagram_prelude_size_t& prelude_size,
                                      fidl::ClientEnd<fuchsia_posix_socket::DatagramSocket> client);

// stream socket (channel backed) --------------------------------------------

zx_status_t zxio_stream_socket_init(zxio_storage_t* storage, zx::socket socket,
                                    const zx_info_socket_t& info, bool is_connected,
                                    fidl::ClientEnd<fuchsia_posix_socket::StreamSocket> client);

// raw socket (channel backed) -------------------------------------------------

zx_status_t zxio_raw_socket_init(zxio_storage_t* storage, zx::eventpair event,
                                 fidl::ClientEnd<fuchsia_posix_socket_raw::Socket> client);

// packet socket (channel backed) ----------------------------------------------

zx_status_t zxio_packet_socket_init(zxio_storage_t* storage, zx::eventpair event,
                                    fidl::ClientEnd<fuchsia_posix_socket_packet::Socket> client);

// vmo -------------------------------------------------------------------------

// Initialize |file| with from a VMO.
//
// The file will be sized to match the underlying VMO by reading the size of the
// VMO from the kernel. The size of a VMO is always a multiple of the page size,
// which means the size of the file will also be a multiple of the page size.
zx_status_t zxio_vmo_init(zxio_storage_t* file, zx::vmo vmo, zx::stream stream);

// Initialize |file| from a channel that implement Closeable and Cloneable.
//
// The file will be transferable to another process.
zx_status_t zxio_transferable_init(zxio_storage_t* file, zx::channel channel);

zx_status_t zxio_create_with_representation(fidl::ClientEnd<fuchsia_io::Node> node,
                                            fuchsia_io::wire::Representation& representation,
                                            zxio_node_attributes_t* attr, zxio_storage_t* storage);

zx::result<zxio_object_type_t> zxio_get_object_type(
    const fidl::ClientEnd<fuchsia_unknown::Queryable>& queryable);

#endif  // LIB_ZXIO_PRIVATE_H_