Return message wrapped in Result from receiveMessage

Changed receivedMessaged return type from status_t to
android::base::Result<>. Enforces checking valid state
before using the object.

Flag: EXEMPT refactor
Bug: 297226446
Test: TEST=libinput_tests; m $TEST && $ANDROID_HOST_OUT/nativetest64/$TEST/$TEST
Change-Id: Ic2285d38a2d0d2227c1fae92379270a5f52586c7

5 files changed, 78 insertions, 70 deletions

diff --git a/include/input/InputTransport.h b/include/input/InputTransport.h
index 6548810ca8..b26a194a0e 100644
--- a/include/input/InputTransport.h
+++ b/include/input/InputTransport.h
@@ -275,7 +275,7 @@ public:
      * Return DEAD_OBJECT if the channel's peer has been closed.
      * Other errors probably indicate that the channel is broken.
      */
-    status_t receiveMessage(InputMessage* msg);
+    android::base::Result<InputMessage> receiveMessage();
 
     /* Tells whether there is a message in the channel available to be received.
      *
diff --git a/libs/input/InputConsumer.cpp b/libs/input/InputConsumer.cpp
index fcf490d5f9..dce528f763 100644
--- a/libs/input/InputConsumer.cpp
+++ b/libs/input/InputConsumer.cpp
@@ -235,8 +235,9 @@ status_t InputConsumer::consume(InputEventFactoryInterface* factory, bool consum
             mMsgDeferred = false;
         } else {
             // Receive a fresh message.
-            status_t result = mChannel->receiveMessage(&mMsg);
-            if (result == OK) {
+            android::base::Result<InputMessage> result = mChannel->receiveMessage();
+            if (result.ok()) {
+                mMsg = std::move(result.value());
                 const auto [_, inserted] =
                         mConsumeTimes.emplace(mMsg.header.seq, systemTime(SYSTEM_TIME_MONOTONIC));
                 LOG_ALWAYS_FATAL_IF(!inserted, "Already have a consume time for seq=%" PRIu32,
@@ -244,11 +245,11 @@ status_t InputConsumer::consume(InputEventFactoryInterface* factory, bool consum
 
                 // Trace the event processing timeline - event was just read from the socket
                 ATRACE_ASYNC_BEGIN(mProcessingTraceTag.c_str(), /*cookie=*/mMsg.header.seq);
-            }
-            if (result) {
+            } else {
                 // Consume the next batched event unless batches are being held for later.
-                if (consumeBatches || result != WOULD_BLOCK) {
-                    result = consumeBatch(factory, frameTime, outSeq, outEvent);
+                if (consumeBatches || result.error().code() != WOULD_BLOCK) {
+                    result = android::base::Error(
+                            consumeBatch(factory, frameTime, outSeq, outEvent));
                     if (*outEvent) {
                         ALOGD_IF(DEBUG_TRANSPORT_CONSUMER,
                                  "channel '%s' consumer ~ consumed batch event, seq=%u",
@@ -256,7 +257,7 @@ status_t InputConsumer::consume(InputEventFactoryInterface* factory, bool consum
                         break;
                     }
                 }
-                return result;
+                return result.error().code();
             }
         }
 
diff --git a/libs/input/InputConsumerNoResampling.cpp b/libs/input/InputConsumerNoResampling.cpp
index 15d992f9f3..e193983d9a 100644
--- a/libs/input/InputConsumerNoResampling.cpp
+++ b/libs/input/InputConsumerNoResampling.cpp
@@ -362,36 +362,36 @@ void InputConsumerNoResampling::handleMessages(std::vector<InputMessage>&& messa
 std::vector<InputMessage> InputConsumerNoResampling::readAllMessages() {
     std::vector<InputMessage> messages;
     while (true) {
-        InputMessage msg;
-        status_t result = mChannel->receiveMessage(&msg);
-        switch (result) {
-            case OK: {
-                const auto [_, inserted] =
-                        mConsumeTimes.emplace(msg.header.seq, systemTime(SYSTEM_TIME_MONOTONIC));
-                LOG_ALWAYS_FATAL_IF(!inserted, "Already have a consume time for seq=%" PRIu32,
-                                    msg.header.seq);
-
-                // Trace the event processing timeline - event was just read from the socket
-                // TODO(b/329777420): distinguish between multiple instances of InputConsumer
-                // in the same process.
-                ATRACE_ASYNC_BEGIN("InputConsumer processing", /*cookie=*/msg.header.seq);
-                messages.push_back(msg);
-                break;
-            }
-            case WOULD_BLOCK: {
-                return messages;
-            }
-            case DEAD_OBJECT: {
-                LOG(FATAL) << "Got a dead object for " << mChannel->getName();
-                break;
-            }
-            case BAD_VALUE: {
-                LOG(FATAL) << "Got a bad value for " << mChannel->getName();
-                break;
-            }
-            default: {
-                LOG(FATAL) << "Unexpected error: " << result;
-                break;
+        android::base::Result<InputMessage> result = mChannel->receiveMessage();
+        if (result.ok()) {
+            const InputMessage& msg = *result;
+            const auto [_, inserted] =
+                    mConsumeTimes.emplace(msg.header.seq, systemTime(SYSTEM_TIME_MONOTONIC));
+            LOG_ALWAYS_FATAL_IF(!inserted, "Already have a consume time for seq=%" PRIu32,
+                                msg.header.seq);
+
+            // Trace the event processing timeline - event was just read from the socket
+            // TODO(b/329777420): distinguish between multiple instances of InputConsumer
+            // in the same process.
+            ATRACE_ASYNC_BEGIN("InputConsumer processing", /*cookie=*/msg.header.seq);
+            messages.push_back(msg);
+        } else { // !result.ok()
+            switch (result.error().code()) {
+                case WOULD_BLOCK: {
+                    return messages;
+                }
+                case DEAD_OBJECT: {
+                    LOG(FATAL) << "Got a dead object for " << mChannel->getName();
+                    break;
+                }
+                case BAD_VALUE: {
+                    LOG(FATAL) << "Got a bad value for " << mChannel->getName();
+                    break;
+                }
+                default: {
+                    LOG(FATAL) << "Unexpected error: " << result.error().message();
+                    break;
+                }
             }
         }
     }
diff --git a/libs/input/InputTransport.cpp b/libs/input/InputTransport.cpp
index 47b422857e..bac681df85 100644
--- a/libs/input/InputTransport.cpp
+++ b/libs/input/InputTransport.cpp
@@ -424,10 +424,11 @@ status_t InputChannel::sendMessage(const InputMessage* msg) {
     return OK;
 }
 
-status_t InputChannel::receiveMessage(InputMessage* msg) {
+android::base::Result<InputMessage> InputChannel::receiveMessage() {
     ssize_t nRead;
+    InputMessage msg;
     do {
-        nRead = ::recv(getFd(), msg, sizeof(InputMessage), MSG_DONTWAIT);
+        nRead = ::recv(getFd(), &msg, sizeof(InputMessage), MSG_DONTWAIT);
     } while (nRead == -1 && errno == EINTR);
 
     if (nRead < 0) {
@@ -435,36 +436,36 @@ status_t InputChannel::receiveMessage(InputMessage* msg) {
         ALOGD_IF(DEBUG_CHANNEL_MESSAGES, "channel '%s' ~ receive message failed, errno=%d",
                  name.c_str(), errno);
         if (error == EAGAIN || error == EWOULDBLOCK) {
-            return WOULD_BLOCK;
+            return android::base::Error(WOULD_BLOCK);
         }
         if (error == EPIPE || error == ENOTCONN || error == ECONNREFUSED) {
-            return DEAD_OBJECT;
+            return android::base::Error(DEAD_OBJECT);
         }
-        return -error;
+        return android::base::Error(-error);
     }
 
     if (nRead == 0) { // check for EOF
         ALOGD_IF(DEBUG_CHANNEL_MESSAGES,
                  "channel '%s' ~ receive message failed because peer was closed", name.c_str());
-        return DEAD_OBJECT;
+        return android::base::Error(DEAD_OBJECT);
     }
 
-    if (!msg->isValid(nRead)) {
+    if (!msg.isValid(nRead)) {
         ALOGE("channel '%s' ~ received invalid message of size %zd", name.c_str(), nRead);
-        return BAD_VALUE;
+        return android::base::Error(BAD_VALUE);
     }
 
     ALOGD_IF(DEBUG_CHANNEL_MESSAGES, "channel '%s' ~ received message of type %s", name.c_str(),
-             ftl::enum_string(msg->header.type).c_str());
+             ftl::enum_string(msg.header.type).c_str());
     if (ATRACE_ENABLED()) {
         // Add an additional trace point to include data about the received message.
         std::string message =
                 StringPrintf("receiveMessage(inputChannel=%s, seq=0x%" PRIx32 ", type=%s)",
-                             name.c_str(), msg->header.seq,
-                             ftl::enum_string(msg->header.type).c_str());
+                             name.c_str(), msg.header.seq,
+                             ftl::enum_string(msg.header.type).c_str());
         ATRACE_NAME(message.c_str());
     }
-    return OK;
+    return msg;
 }
 
 bool InputChannel::probablyHasInput() const {
@@ -729,15 +730,16 @@ status_t InputPublisher::publishTouchModeEvent(uint32_t seq, int32_t eventId, bo
 }
 
 android::base::Result<InputPublisher::ConsumerResponse> InputPublisher::receiveConsumerResponse() {
-    InputMessage msg;
-    status_t result = mChannel->receiveMessage(&msg);
-    if (result) {
-        if (debugTransportPublisher() && result != WOULD_BLOCK) {
+    android::base::Result<InputMessage> result = mChannel->receiveMessage();
+    if (!result.ok()) {
+        if (debugTransportPublisher() && result.error().code() != WOULD_BLOCK) {
             LOG(INFO) << "channel '" << mChannel->getName() << "' publisher ~ " << __func__ << ": "
-                      << strerror(result);
+                      << result.error().message();
         }
-        return android::base::Error(result);
+        return result.error();
     }
+
+    const InputMessage& msg = *result;
     if (msg.header.type == InputMessage::Type::FINISHED) {
         ALOGD_IF(debugTransportPublisher(),
                  "channel '%s' publisher ~ %s: finished: seq=%u, handled=%s",
diff --git a/libs/input/tests/InputChannel_test.cpp b/libs/input/tests/InputChannel_test.cpp
index 02d4c07bfa..435bdcde2d 100644
--- a/libs/input/tests/InputChannel_test.cpp
+++ b/libs/input/tests/InputChannel_test.cpp
@@ -78,9 +78,10 @@ TEST_F(InputChannelTest, OpenInputChannelPair_ReturnsAPairOfConnectedChannels) {
     EXPECT_EQ(OK, serverChannel->sendMessage(&serverMsg))
             << "server channel should be able to send message to client channel";
 
-    InputMessage clientMsg;
-    EXPECT_EQ(OK, clientChannel->receiveMessage(&clientMsg))
+    android::base::Result<InputMessage> clientMsgResult = clientChannel->receiveMessage();
+    ASSERT_TRUE(clientMsgResult.ok())
             << "client channel should be able to receive message from server channel";
+    const InputMessage& clientMsg = *clientMsgResult;
     EXPECT_EQ(serverMsg.header.type, clientMsg.header.type)
             << "client channel should receive the correct message from server channel";
     EXPECT_EQ(serverMsg.body.key.action, clientMsg.body.key.action)
@@ -94,9 +95,10 @@ TEST_F(InputChannelTest, OpenInputChannelPair_ReturnsAPairOfConnectedChannels) {
     EXPECT_EQ(OK, clientChannel->sendMessage(&clientReply))
             << "client channel should be able to send message to server channel";
 
-    InputMessage serverReply;
-    EXPECT_EQ(OK, serverChannel->receiveMessage(&serverReply))
+    android::base::Result<InputMessage> serverReplyResult = serverChannel->receiveMessage();
+    ASSERT_TRUE(serverReplyResult.ok())
             << "server channel should be able to receive message from client channel";
+    const InputMessage& serverReply = *serverReplyResult;
     EXPECT_EQ(clientReply.header.type, serverReply.header.type)
             << "server channel should receive the correct message from client channel";
     EXPECT_EQ(clientReply.header.seq, serverReply.header.seq)
@@ -134,9 +136,10 @@ TEST_F(InputChannelTest, ProbablyHasInput) {
             << "client channel should observe that message is available before receiving it";
 
     // Receive (consume) the message.
-    InputMessage clientMsg;
-    EXPECT_EQ(OK, receiverChannel->receiveMessage(&clientMsg))
+    android::base::Result<InputMessage> clientMsgResult = receiverChannel->receiveMessage();
+    ASSERT_TRUE(clientMsgResult.ok())
             << "client channel should be able to receive message from server channel";
+    const InputMessage& clientMsg = *clientMsgResult;
     EXPECT_EQ(serverMsg.header.type, clientMsg.header.type)
             << "client channel should receive the correct message from server channel";
     EXPECT_EQ(serverMsg.body.key.action, clientMsg.body.key.action)
@@ -156,8 +159,8 @@ TEST_F(InputChannelTest, ReceiveSignal_WhenNoSignalPresent_ReturnsAnError) {
     ASSERT_EQ(OK, result)
             << "should have successfully opened a channel pair";
 
-    InputMessage msg;
-    EXPECT_EQ(WOULD_BLOCK, clientChannel->receiveMessage(&msg))
+    android::base::Result<InputMessage> msgResult = clientChannel->receiveMessage();
+    EXPECT_EQ(WOULD_BLOCK, msgResult.error().code())
             << "receiveMessage should have returned WOULD_BLOCK";
 }
 
@@ -172,8 +175,8 @@ TEST_F(InputChannelTest, ReceiveSignal_WhenPeerClosed_ReturnsAnError) {
 
     serverChannel.reset(); // close server channel
 
-    InputMessage msg;
-    EXPECT_EQ(DEAD_OBJECT, clientChannel->receiveMessage(&msg))
+    android::base::Result<InputMessage> msgResult = clientChannel->receiveMessage();
+    EXPECT_EQ(DEAD_OBJECT, msgResult.error().code())
             << "receiveMessage should have returned DEAD_OBJECT";
 }
 
@@ -207,7 +210,7 @@ TEST_F(InputChannelTest, SendAndReceive_MotionClassification) {
         MotionClassification::DEEP_PRESS,
     };
 
-    InputMessage serverMsg = {}, clientMsg;
+    InputMessage serverMsg = {};
     serverMsg.header.type = InputMessage::Type::MOTION;
     serverMsg.header.seq = 1;
     serverMsg.body.motion.pointerCount = 1;
@@ -218,11 +221,13 @@ TEST_F(InputChannelTest, SendAndReceive_MotionClassification) {
         EXPECT_EQ(OK, serverChannel->sendMessage(&serverMsg))
                 << "server channel should be able to send message to client channel";
 
-        EXPECT_EQ(OK, clientChannel->receiveMessage(&clientMsg))
+        android::base::Result<InputMessage> clientMsgResult = clientChannel->receiveMessage();
+        ASSERT_TRUE(clientMsgResult.ok())
                 << "client channel should be able to receive message from server channel";
+        const InputMessage& clientMsg = *clientMsgResult;
         EXPECT_EQ(serverMsg.header.type, clientMsg.header.type);
-        EXPECT_EQ(classification, clientMsg.body.motion.classification) <<
-                "Expected to receive " << motionClassificationToString(classification);
+        EXPECT_EQ(classification, clientMsg.body.motion.classification)
+                << "Expected to receive " << motionClassificationToString(classification);
     }
 }