Merge "logd: Allow setDropped() to be called on already dropped messages" (e54366eb) · Commits · e / os / android_system_core

logd/LogBufferElement.cpp

+31 −26

Original line number	Diff line number	Diff line
		@@ -56,14 +56,7 @@ LogBufferElement::LogBufferElement(const LogBufferElement& elem)
		mLogId(elem.mLogId),
		mDropped(elem.mDropped) {
		if (mDropped) {
		if (elem.isBinary() && elem.mMsg != nullptr) {
		// for the following "len" value, refer to : setDropped(uint16_t value), getTag()
		const int len = sizeof(android_event_header_t);
		mMsg = new char[len];
		memcpy(mMsg, elem.mMsg, len);
		} else {
		mMsg = nullptr;
		}
		mTag = elem.getTag();
		} else {
		mMsg = new char[mMsgLen];
		memcpy(mMsg, elem.mMsg, mMsgLen);
		@@ -71,31 +64,43 @@ LogBufferElement::LogBufferElement(const LogBufferElement& elem)
		}

		LogBufferElement::~LogBufferElement() {
		if (!mDropped) {
		delete[] mMsg;
		}
		}

		uint32_t LogBufferElement::getTag() const {
		return (isBinary() &&
		((mDropped && mMsg != nullptr) \|\|
		(!mDropped && mMsgLen >= sizeof(android_event_header_t))))
		? reinterpret_cast<const android_event_header_t*>(mMsg)->tag
		: 0;
		// Binary buffers have no tag.
		if (!isBinary()) {
		return 0;
		}

		// Dropped messages store the tag in place of mMsg.
		if (mDropped) {
		return mTag;
		}

		// For non-dropped messages, we get the tag from the message header itself.
		if (mMsgLen < sizeof(android_event_header_t)) {
		return 0;
		}

		return reinterpret_cast<const android_event_header_t*>(mMsg)->tag;
		}

		uint16_t LogBufferElement::setDropped(uint16_t value) {
		// The tag information is saved in mMsg data, if the tag is non-zero
		// save only the information needed to get the tag.
		if (getTag() != 0) {
		if (mMsgLen > sizeof(android_event_header_t)) {
		char* truncated_msg = new char[sizeof(android_event_header_t)];
		memcpy(truncated_msg, mMsg, sizeof(android_event_header_t));
		delete[] mMsg;
		mMsg = truncated_msg;
		} // mMsgLen == sizeof(android_event_header_t), already at minimum.
		} else {
		if (mDropped) {
		return mDroppedCount = value;
		}

		// The tag information is saved in mMsg data, which is in a union with mTag, used after mDropped
		// is set to true. Therefore we save the tag value aside, delete mMsg, then set mTag to the tag
		// value in its place.
		auto old_tag = getTag();
		delete[] mMsg;
		mMsg = nullptr;
		}

		mTag = old_tag;
		mDropped = true;
		return mDroppedCount = value;
		}

logd/LogBufferElement.h

+4 −1

Original line number	Diff line number	Diff line
		@@ -41,7 +41,10 @@ class __attribute__((packed)) LogBufferElement {
		const uint32_t mPid;
		const uint32_t mTid;
		log_time mRealTime;
		char* mMsg;
		union {
		char* mMsg; // mDropped == false
		int32_t mTag; // mDropped == true
		};
		union {
		const uint16_t mMsgLen; // mDropped == false
		uint16_t mDroppedCount; // mDropped == true