sdk/lib/fidl/cpp/wire/outgoing_message.cc

// Copyright 2022 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 <lib/fidl/cpp/wire/incoming_message.h>
#include <lib/fidl/cpp/wire/outgoing_message.h>

#ifdef __Fuchsia__
#include <lib/fidl/cpp/wire/internal/transport_channel.h>
#else
#include <lib/fidl/cpp/wire/internal/transport_channel_host.h>
#endif  // __Fuchsia__

namespace fidl {

OutgoingMessage::OutgoingMessage(const ::fidl::Status& failure)
    : fidl::Status(failure), message_({}) {
  ZX_DEBUG_ASSERT(failure.status() != ZX_OK);
}

OutgoingMessage::OutgoingMessage(InternalIovecConstructorArgs args)
    : fidl::Status(fidl::Status::Ok()), message_(args) {}

OutgoingMessage::~OutgoingMessage() {
  // We may not have a vtable when the |OutgoingMessage| represents an error.
  if (message_.transport_vtable) {
    message_.transport_vtable->encoding_configuration->close_many(handles(), handle_actual());
  }
}

uint32_t OutgoingMessage::CountBytes() const {
  uint32_t byte_count = 0;
  for (uint32_t i = 0; i < iovec_actual(); ++i) {
    byte_count += iovecs()[i].capacity;
  }
  return byte_count;
}

bool OutgoingMessage::BytesMatch(const OutgoingMessage& other) const {
  uint32_t iovec_index = 0, other_iovec_index = 0;
  uint32_t byte_index = 0, other_byte_index = 0;
  while (iovec_index < iovec_actual() && other_iovec_index < other.iovec_actual()) {
    zx_channel_iovec_t cur_iovec = iovecs()[iovec_index];
    zx_channel_iovec_t other_cur_iovec = other.iovecs()[other_iovec_index];
    const uint8_t* cur_bytes = reinterpret_cast<const uint8_t*>(cur_iovec.buffer);
    const uint8_t* other_cur_bytes = reinterpret_cast<const uint8_t*>(other_cur_iovec.buffer);

    uint32_t cmp_len =
        std::min(cur_iovec.capacity - byte_index, other_cur_iovec.capacity - other_byte_index);
    if (memcmp(&cur_bytes[byte_index], &other_cur_bytes[other_byte_index], cmp_len) != 0) {
      return false;
    }

    byte_index += cmp_len;
    if (byte_index == cur_iovec.capacity) {
      iovec_index++;
      byte_index = 0;
    }
    other_byte_index += cmp_len;
    if (other_byte_index == other_cur_iovec.capacity) {
      other_iovec_index++;
      other_byte_index = 0;
    }
  }
  return iovec_index == iovec_actual() && other_iovec_index == other.iovec_actual() &&
         byte_index == 0 && other_byte_index == 0;
}

void OutgoingMessage::EncodeImpl(fidl::internal::WireFormatVersion wire_format_version, void* data,
                                 size_t inline_size, fidl::internal::TopLevelEncodeFn encode_fn) {
  if (unlikely(!ok())) {
    return;
  }
  if (unlikely(wire_format_version != fidl::internal::WireFormatVersion::kV2)) {
    SetStatus(fidl::Status::EncodeError(ZX_ERR_INVALID_ARGS, "only v2 wire format supported"));
    return;
  }

  fit::result<fidl::Error, fidl::internal::WireEncoder::Result> result = fidl::internal::WireEncode(
      inline_size, encode_fn, message_.transport_vtable->encoding_configuration, data, iovecs(),
      iovec_capacity(), handles(), message_.handle_metadata, handle_capacity(), backing_buffer(),
      backing_buffer_capacity());
  if (unlikely(!result.is_ok())) {
    SetStatus(result.error_value());
    return;
  }
  message_.num_iovecs = static_cast<uint32_t>(result.value().iovec_actual);
  message_.num_handles = static_cast<uint32_t>(result.value().handle_actual);
}

void OutgoingMessage::Write(internal::AnyUnownedTransport transport, WriteOptions options) {
  if (unlikely(!ok())) {
    return;
  }
  ZX_ASSERT(transport_type() == transport.type());
  ZX_ASSERT(is_transactional());
  zx_status_t status =
      transport.write(std::move(options), internal::WriteArgs{
                                              .data = iovecs(),
                                              .handles = handles(),
                                              .handle_metadata = message_.handle_metadata,
                                              .data_count = iovec_actual(),
                                              .handles_count = handle_actual(),
                                          });
  ReleaseHandles();
  if (unlikely(status != ZX_OK)) {
    SetStatus(fidl::Status::TransportError(status));
  }
}

IncomingHeaderAndMessage OutgoingMessage::CallImpl(internal::AnyUnownedTransport transport,
                                                   internal::MessageStorageViewBase& storage,
                                                   CallOptions options) {
  if (status() != ZX_OK) {
    return IncomingHeaderAndMessage::Create(Status(*this));
  }
  ZX_ASSERT(transport_type() == transport.type());
  ZX_ASSERT(is_transactional());

  uint8_t* result_bytes;
  fidl_handle_t* result_handles;
  fidl_handle_metadata_t* result_handle_metadata;
  uint32_t actual_num_bytes = 0u;
  uint32_t actual_num_handles = 0u;
  internal::CallMethodArgs args = {
      .wr =
          internal::WriteArgs{
              .data = iovecs(),
              .handles = handles(),
              .handle_metadata = message_.handle_metadata,
              .data_count = iovec_actual(),
              .handles_count = handle_actual(),
          },
      .rd =
          internal::ReadArgs{
              .storage_view = &storage,
              .out_data = reinterpret_cast<void**>(&result_bytes),
              .out_handles = &result_handles,
              .out_handle_metadata = &result_handle_metadata,
              .out_data_actual_count = &actual_num_bytes,
              .out_handles_actual_count = &actual_num_handles,
          },
  };

  zx_status_t status = transport.call(std::move(options), args);
  ReleaseHandles();
  if (status != ZX_OK) {
    SetStatus(fidl::Status::TransportError(status));
    return IncomingHeaderAndMessage::Create(Status(*this));
  }

  return IncomingHeaderAndMessage(message_.transport_vtable, result_bytes, actual_num_bytes,
                                  result_handles, result_handle_metadata, actual_num_handles);
}

OutgoingMessage::CopiedBytes::CopiedBytes(const OutgoingMessage& msg) {
  uint32_t byte_count = 0;
  for (uint32_t i = 0; i < msg.iovec_actual(); ++i) {
    byte_count += msg.iovecs()[i].capacity;
  }
  bytes_.reserve(byte_count);
  for (uint32_t i = 0; i < msg.iovec_actual(); ++i) {
    zx_channel_iovec_t iovec = msg.iovecs()[i];
    const uint8_t* buf_bytes = reinterpret_cast<const uint8_t*>(iovec.buffer);
    bytes_.insert(bytes_.end(), buf_bytes, buf_bytes + iovec.capacity);
  }
}

}  // namespace fidl