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// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_DBUS_UTILS_CALL_METHOD_H_
#define COMPONENTS_DBUS_UTILS_CALL_METHOD_H_
#include <dbus/dbus.h>
#include <numeric>
#include <string>
#include <tuple>
#include <utility>
#include "base/component_export.h"
#include "base/functional/callback.h"
#include "base/numerics/clamped_math.h"
#include "base/time/time.h"
#include "base/types/expected.h"
#include "components/dbus/utils/read_value.h"
#include "components/dbus/utils/signature.h"
#include "components/dbus/utils/types.h"
#include "components/dbus/utils/variant.h"
#include "components/dbus/utils/write_value.h"
#include "dbus/message.h"
#include "dbus/object_proxy.h"
namespace dbus_utils {
namespace internal {
template <typename... Ts>
std::tuple<Ts...> Unwrap(std::tuple<std::optional<Ts>...> input) {
return std::apply(
[](auto&&... args) { return std::tuple(*std::move(args)...); },
std::move(input));
}
} // namespace internal
enum class CallMethodErrorStatus {
kErrorResponse = 0,
kExtraDataInResponse = 1,
kNoResponse = 2,
kInvalidResponseFormat = 3,
};
constexpr base::TimeDelta kTimeoutDefault =
base::Milliseconds(dbus::ObjectProxy::TIMEOUT_USE_DEFAULT);
constexpr base::TimeDelta kTimeoutMax =
base::Milliseconds(dbus::ObjectProxy::TIMEOUT_MAX);
class COMPONENT_EXPORT(COMPONENTS_DBUS) CallMethodError {
public:
CallMethodError(CallMethodErrorStatus status,
dbus::ErrorResponse* error_response);
const CallMethodErrorStatus status;
// These members are only set if `status` is `kErrorResponse`.
const std::string error_name;
const std::string error_message;
};
template <typename... Rets>
using CallMethodResult = base::expected<std::tuple<Rets...>, CallMethodError>;
// This is similar to dbus::ObjectProxy::CallMethod, except the MethodCall,
// MessageWriter, and MessageReader logic is contained within. The method
// arguments and reply type are specified in `args` and `callback`,
// respectively. This is intended to be used on Linux where a C++ bindings
// generator is not available, to allow a more declarative style of calling
// D-Bus methods. The first argument to `callback` is a status code, and the
// remaining arguments are deserialized from the reply, or default-constructed
// if they could not be deserialized. Two template arguments are required:
// `ArgsSignature` and `RetsSignature`, which are C string literals that
// must match the D-Bus signature of the method arguments and reply.
template <internal::StringLiteral ArgsSignature,
internal::StringLiteral RetsSignature,
typename... Args,
typename... Rets>
void CallMethod(dbus::ObjectProxy* proxy,
const std::string& interface,
const std::string& method,
base::TimeDelta timeout,
base::OnceCallback<void(CallMethodResult<Rets...>)> callback,
const Args&... args)
requires((internal::IsSupportedDBusType<Args> && ...) &&
(internal::IsSupportedDBusType<Rets> && ...) &&
(internal::StrJoin(
(internal::DBusSignature<std::decay_t<Args>>::kValue)...) ==
ArgsSignature.value) &&
(internal::StrJoin(
(internal::DBusSignature<std::decay_t<Rets>>::kValue)...) ==
RetsSignature.value))
{
dbus::MethodCall dbus_call(interface, method);
dbus::MessageWriter writer(&dbus_call);
(internal::WriteValue(writer, args), ...);
base::ClampedNumeric<int32_t> timeout_ms = timeout.InMilliseconds();
proxy->CallMethodWithErrorResponse(
&dbus_call, timeout_ms,
base::BindOnce(
[](base::OnceCallback<void(CallMethodResult<Rets...>)> cb,
dbus::Response* response, dbus::ErrorResponse* error_response) {
if (response) {
std::tuple<std::optional<Rets>...> rets;
dbus::MessageReader reader(response);
const bool success = std::apply(
[&](auto&... value) {
auto read_and_assign = [&](auto& member) {
using OptionalType =
std::remove_cvref_t<decltype(member)>;
if (auto result = internal::ReadValue<
typename OptionalType::value_type>(reader)) {
member = std::move(*result);
return true;
}
return false;
};
return (read_and_assign(value) && ...);
},
rets);
if (!success) {
std::move(cb).Run(base::unexpected(CallMethodError(
CallMethodErrorStatus::kInvalidResponseFormat,
nullptr)));
} else if (reader.HasMoreData()) {
std::move(cb).Run(base::unexpected(
CallMethodError(CallMethodErrorStatus::kExtraDataInResponse,
nullptr)));
} else {
std::move(cb).Run(internal::Unwrap(std::move(rets)));
}
} else if (error_response) {
std::move(cb).Run(base::unexpected(CallMethodError(
CallMethodErrorStatus::kErrorResponse, error_response)));
} else {
std::move(cb).Run(base::unexpected(CallMethodError(
CallMethodErrorStatus::kNoResponse, nullptr)));
}
},
std::move(callback)));
}
// This is a convenience overload of CallMethod that uses the default timeout.
template <internal::StringLiteral ArgsSignature,
internal::StringLiteral RetsSignature,
typename... Args,
typename... Rets>
void CallMethod(dbus::ObjectProxy* proxy,
const std::string& interface,
const std::string& method,
base::OnceCallback<void(CallMethodResult<Rets...>)> callback,
const Args&... args)
requires((internal::IsSupportedDBusType<Args> && ...) &&
(internal::IsSupportedDBusType<Rets> && ...) &&
(internal::StrJoin(
(internal::DBusSignature<std::decay_t<Args>>::kValue)...) ==
ArgsSignature.value) &&
(internal::StrJoin(
(internal::DBusSignature<std::decay_t<Rets>>::kValue)...) ==
RetsSignature.value))
{
CallMethod<ArgsSignature, RetsSignature>(
proxy, interface, method, kTimeoutDefault, std::move(callback), args...);
}
} // namespace dbus_utils
#endif // COMPONENTS_DBUS_UTILS_CALL_METHOD_H_
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