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// Copyright 2016 The Chromium 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 "mojo/edk/system/message_for_transit.h"
#include <vector>
#include "mojo/edk/embedder/platform_handle_vector.h"
namespace mojo {
namespace edk {
namespace {
static_assert(sizeof(MessageForTransit::MessageHeader) % 8 == 0,
"Invalid MessageHeader size.");
static_assert(sizeof(MessageForTransit::DispatcherHeader) % 8 == 0,
"Invalid DispatcherHeader size.");
} // namespace
MessageForTransit::~MessageForTransit() {}
// static
MojoResult MessageForTransit::Create(
std::unique_ptr<MessageForTransit>* message,
uint32_t num_bytes,
const Dispatcher::DispatcherInTransit* dispatchers,
uint32_t num_dispatchers) {
// A structure for retaining information about every Dispatcher that will be
// sent with this message.
struct DispatcherInfo {
uint32_t num_bytes;
uint32_t num_ports;
uint32_t num_handles;
};
// This is only the base header size. It will grow as we accumulate the
// size of serialized state for each dispatcher.
size_t header_size = sizeof(MessageHeader) +
num_dispatchers * sizeof(DispatcherHeader);
size_t num_ports = 0;
size_t num_handles = 0;
std::vector<DispatcherInfo> dispatcher_info(num_dispatchers);
for (size_t i = 0; i < num_dispatchers; ++i) {
Dispatcher* d = dispatchers[i].dispatcher.get();
d->StartSerialize(&dispatcher_info[i].num_bytes,
&dispatcher_info[i].num_ports,
&dispatcher_info[i].num_handles);
header_size += dispatcher_info[i].num_bytes;
num_ports += dispatcher_info[i].num_ports;
num_handles += dispatcher_info[i].num_handles;
}
// We now have enough information to fully allocate the message storage.
std::unique_ptr<PortsMessage> msg = PortsMessage::NewUserMessage(
header_size + num_bytes, num_ports, num_handles);
if (!msg)
return MOJO_RESULT_RESOURCE_EXHAUSTED;
// Populate the message header with information about serialized dispatchers.
//
// The front of the message is always a MessageHeader followed by a
// DispatcherHeader for each dispatcher to be sent.
MessageHeader* header =
static_cast<MessageHeader*>(msg->mutable_payload_bytes());
DispatcherHeader* dispatcher_headers =
reinterpret_cast<DispatcherHeader*>(header + 1);
// Serialized dispatcher state immediately follows the series of
// DispatcherHeaders.
char* dispatcher_data =
reinterpret_cast<char*>(dispatcher_headers + num_dispatchers);
header->num_dispatchers = num_dispatchers;
// |header_size| is the total number of bytes preceding the message payload,
// including all dispatcher headers and serialized dispatcher state.
DCHECK_LE(header_size, std::numeric_limits<uint32_t>::max());
header->header_size = static_cast<uint32_t>(header_size);
if (num_dispatchers > 0) {
ScopedPlatformHandleVectorPtr handles(
new PlatformHandleVector(num_handles));
size_t port_index = 0;
size_t handle_index = 0;
bool fail = false;
for (size_t i = 0; i < num_dispatchers; ++i) {
Dispatcher* d = dispatchers[i].dispatcher.get();
DispatcherHeader* dh = &dispatcher_headers[i];
const DispatcherInfo& info = dispatcher_info[i];
// Fill in the header for this dispatcher.
dh->type = static_cast<int32_t>(d->GetType());
dh->num_bytes = info.num_bytes;
dh->num_ports = info.num_ports;
dh->num_platform_handles = info.num_handles;
// Fill in serialized state, ports, and platform handles. We'll cancel
// the send if the dispatcher implementation rejects for some reason.
if (!d->EndSerialize(static_cast<void*>(dispatcher_data),
msg->mutable_ports() + port_index,
handles->data() + handle_index)) {
fail = true;
break;
}
dispatcher_data += info.num_bytes;
port_index += info.num_ports;
handle_index += info.num_handles;
}
if (fail) {
// Release any platform handles we've accumulated. Their dispatchers
// retain ownership when message creation fails, so these are not actually
// leaking.
handles->clear();
return MOJO_RESULT_INVALID_ARGUMENT;
}
// Take ownership of all the handles and move them into message storage.
msg->SetHandles(std::move(handles));
}
message->reset(new MessageForTransit(std::move(msg)));
return MOJO_RESULT_OK;
}
MessageForTransit::MessageForTransit(std::unique_ptr<PortsMessage> message)
: message_(std::move(message)) {
}
} // namespace edk
} // namespace mojo
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