1 files changed, 15 insertions, 7 deletions

diff --git a/include/input/InputTransport.h b/include/input/InputTransport.h
index 8ffdfca..e7e383b 100644
--- a/include/input/InputTransport.h
+++ b/include/input/InputTransport.h
@@ -39,6 +39,9 @@ namespace android {
 
 /*
  * Intermediate representation used to send input events and related signals.
+ *
+ * Note that this structure is used for IPCs so its layout must be identical
+ * on 64 and 32 bit processes. This is tested in StructLayout_test.cpp.
  */
 struct InputMessage {
     enum {
@@ -49,13 +52,17 @@ struct InputMessage {
 
     struct Header {
         uint32_t type;
-        uint32_t padding; // 8 byte alignment for the body that follows
+        // We don't need this field in order to align the body below but we
+        // leave it here because InputMessage::size() and other functions
+        // compute the size of this structure as sizeof(Header) + sizeof(Body).
+        uint32_t padding;
     } header;
 
+    // Body *must* be 8 byte aligned.
     union Body {
         struct Key {
             uint32_t seq;
-            nsecs_t eventTime;
+            nsecs_t eventTime __attribute__((aligned(8)));
             int32_t deviceId;
             int32_t source;
             int32_t action;
@@ -64,7 +71,7 @@ struct InputMessage {
             int32_t scanCode;
             int32_t metaState;
             int32_t repeatCount;
-            nsecs_t downTime;
+            nsecs_t downTime __attribute__((aligned(8)));
 
             inline size_t size() const {
                 return sizeof(Key);
@@ -73,7 +80,7 @@ struct InputMessage {
 
         struct Motion {
             uint32_t seq;
-            nsecs_t eventTime;
+            nsecs_t eventTime __attribute__((aligned(8)));
             int32_t deviceId;
             int32_t source;
             int32_t action;
@@ -81,13 +88,14 @@ struct InputMessage {
             int32_t metaState;
             int32_t buttonState;
             int32_t edgeFlags;
-            nsecs_t downTime;
+            nsecs_t downTime __attribute__((aligned(8)));
             float xOffset;
             float yOffset;
             float xPrecision;
             float yPrecision;
             uint32_t pointerCount;
-            struct Pointer {
+            // Note that PointerCoords requires 8 byte alignment.
+            struct Pointer{
                 PointerProperties properties;
                 PointerCoords coords;
             } pointers[MAX_POINTERS];
@@ -112,7 +120,7 @@ struct InputMessage {
                 return sizeof(Finished);
             }
         } finished;
-    } body;
+    } __attribute__((aligned(8))) body;
 
     bool isValid(size_t actualSize) const;
     size_t size() const;