MotionEvent: add safe dumping method

This method should allow us to log more details of an event in case of
validation failures, without potential for infinite recursion in getter
methods.

Bug: 379368465
Test: add a test to MotionEventTest that calls
      getHistoricalRawPointerCoords with an invalid pointer index, and
      check the logs when run with `atest --host`
Flag: EXEMPT logs only
Change-Id: I9c7084cedbc7e6f6834cd1b401da04d07d22ce35

2 files changed, 64 insertions, 8 deletions

diff --git a/include/input/Input.h b/include/input/Input.h
index a8684bd19b..0e330e453b 100644
--- a/include/input/Input.h
+++ b/include/input/Input.h
@@ -994,6 +994,15 @@ protected:
     std::vector<PointerProperties> mPointerProperties;
     std::vector<nsecs_t> mSampleEventTimes;
     std::vector<PointerCoords> mSamplePointerCoords;
+
+private:
+    /**
+     * Create a human-readable string representation of the event's data for debugging purposes.
+     *
+     * Unlike operator<<, this method does not assume that the event data is valid or consistent, or
+     * call any accessor methods that might themselves call safeDump in the case of invalid data.
+     */
+    std::string safeDump() const;
 };
 
 std::ostream& operator<<(std::ostream& out, const MotionEvent& event);
diff --git a/libs/input/Input.cpp b/libs/input/Input.cpp
index b87a7068b5..65a088eb6d 100644
--- a/libs/input/Input.cpp
+++ b/libs/input/Input.cpp
@@ -685,11 +685,12 @@ void MotionEvent::setCursorPosition(float x, float y) {
 
 const PointerCoords* MotionEvent::getRawPointerCoords(size_t pointerIndex) const {
     if (CC_UNLIKELY(pointerIndex < 0 || pointerIndex >= getPointerCount())) {
-        LOG(FATAL) << __func__ << ": Invalid pointer index " << pointerIndex << " for " << *this;
+        LOG(FATAL) << __func__ << ": Invalid pointer index " << pointerIndex << " for "
+                   << safeDump();
     }
     const size_t position = getHistorySize() * getPointerCount() + pointerIndex;
     if (CC_UNLIKELY(position < 0 || position >= mSamplePointerCoords.size())) {
-        LOG(FATAL) << __func__ << ": Invalid array index " << position << " for " << *this;
+        LOG(FATAL) << __func__ << ": Invalid array index " << position << " for " << safeDump();
     }
     return &mSamplePointerCoords[position];
 }
@@ -705,17 +706,16 @@ float MotionEvent::getAxisValue(int32_t axis, size_t pointerIndex) const {
 const PointerCoords* MotionEvent::getHistoricalRawPointerCoords(
         size_t pointerIndex, size_t historicalIndex) const {
     if (CC_UNLIKELY(pointerIndex < 0 || pointerIndex >= getPointerCount())) {
-        LOG(FATAL) << __func__ << ": Invalid pointer index " << pointerIndex
-                   << "; should be between >0 and ≤" << getPointerCount();
+        LOG(FATAL) << __func__ << ": Invalid pointer index " << pointerIndex << " for "
+                   << safeDump();
     }
     if (CC_UNLIKELY(historicalIndex < 0 || historicalIndex > getHistorySize())) {
-        LOG(FATAL) << __func__ << ": Invalid historical index " << historicalIndex
-                   << "; should be >0 and ≤" << getHistorySize();
+        LOG(FATAL) << __func__ << ": Invalid historical index " << historicalIndex << " for "
+                   << safeDump();
     }
     const size_t position = historicalIndex * getPointerCount() + pointerIndex;
     if (CC_UNLIKELY(position < 0 || position >= mSamplePointerCoords.size())) {
-        LOG(FATAL) << __func__ << ": Invalid array index " << position << "; should be >0 and ≤"
-                   << mSamplePointerCoords.size();
+        LOG(FATAL) << __func__ << ": Invalid array index " << position << " for " << safeDump();
     }
     return &mSamplePointerCoords[position];
 }
@@ -1146,6 +1146,53 @@ bool MotionEvent::operator==(const android::MotionEvent& o) const {
     // clang-format on
 }
 
+std::string MotionEvent::safeDump() const {
+    std::stringstream out;
+    // Field names have the m prefix here to make it easy to distinguish safeDump output from
+    // operator<< output in logs.
+    out << "MotionEvent { mAction=" << MotionEvent::actionToString(mAction);
+    if (mActionButton != 0) {
+        out << ", mActionButton=" << mActionButton;
+    }
+    if (mButtonState != 0) {
+        out << ", mButtonState=" << mButtonState;
+    }
+    if (mClassification != MotionClassification::NONE) {
+        out << ", mClassification=" << motionClassificationToString(mClassification);
+    }
+    if (mMetaState != 0) {
+        out << ", mMetaState=" << mMetaState;
+    }
+    if (mFlags != 0) {
+        out << ", mFlags=0x" << std::hex << mFlags << std::dec;
+    }
+    if (mEdgeFlags != 0) {
+        out << ", mEdgeFlags=" << mEdgeFlags;
+    }
+    out << ", mDownTime=" << mDownTime;
+    out << ", mDeviceId=" << mDeviceId;
+    out << ", mSource=" << inputEventSourceToString(mSource);
+    out << ", mDisplayId=" << mDisplayId;
+    out << ", mEventId=0x" << std::hex << mId << std::dec;
+    // Since we're not assuming the data is at all valid, we also limit the number of items that
+    // might be printed from vectors, in case the vector's size field is corrupted.
+    out << ", mPointerProperties=(" << mPointerProperties.size() << ")[";
+    for (size_t i = 0; i < mPointerProperties.size() && i < MAX_POINTERS; i++) {
+        out << (i > 0 ? ", " : "") << mPointerProperties.at(i);
+    }
+    out << "], mSampleEventTimes=(" << mSampleEventTimes.size() << ")[";
+    for (size_t i = 0; i < mSampleEventTimes.size() && i < 256; i++) {
+        out << (i > 0 ? ", " : "") << mSampleEventTimes.at(i);
+    }
+    out << "], mSamplePointerCoords=(" << mSamplePointerCoords.size() << ")[";
+    for (size_t i = 0; i < mSamplePointerCoords.size() && i < MAX_POINTERS; i++) {
+        const PointerCoords& coords = mSamplePointerCoords.at(i);
+        out << (i > 0 ? ", " : "") << "(" << coords.getX() << ", " << coords.getY() << ")";
+    }
+    out << "] }";
+    return out.str();
+}
+
 std::ostream& operator<<(std::ostream& out, const MotionEvent& event) {
     out << "MotionEvent { action=" << MotionEvent::actionToString(event.getAction());
     if (event.getActionButton() != 0) {