libui: Clean up Fence and Region flattening

Fence was flattening incorrectly, causing issues with any fields
flattened after it, and Region was relying on being the last object
flattened. This change addresses both.

Change-Id: If49de061de6e2f11f4d846b4d8c18627dfb7e109

libs/ui/Fence.cpp

@@ -130,7 +130,7 @@ nsecs_t Fence::getSignalTime() const {
 }
 
 size_t Fence::getFlattenedSize() const {
-    return 1;
+    return 4;
 }
 
 size_t Fence::getFdCount() const {
@@ -141,7 +141,9 @@ status_t Fence::flatten(void*& buffer, size_t& size, int*& fds, size_t& count) c
     if (size < getFlattenedSize() || count < getFdCount()) {
         return NO_MEMORY;
     }
-    FlattenableUtils::write(buffer, size, getFdCount());
+    // Cast to uint32_t since the size of a size_t can vary between 32- and
+    // 64-bit processes
+    FlattenableUtils::write(buffer, size, static_cast<uint32_t>(getFdCount()));
     if (isValid()) {
         *fds++ = mFenceFd;
         count--;

libs/ui/Region.cpp

@@ -754,35 +754,52 @@ void Region::translate(Region& dst, const Region& reg, int dx, int dy)
 // ----------------------------------------------------------------------------
 
 size_t Region::getFlattenedSize() const {
-    return mStorage.size() * sizeof(Rect);
+    return sizeof(uint32_t) + mStorage.size() * sizeof(Rect);
 }
 
 status_t Region::flatten(void* buffer, size_t size) const {
 #if VALIDATE_REGIONS
     validate(*this, "Region::flatten");
 #endif
-    if (size < mStorage.size() * sizeof(Rect)) {
+    if (size < getFlattenedSize()) {
         return NO_MEMORY;
     }
-    Rect* rects = reinterpret_cast<Rect*>(buffer);
+    // Cast to uint32_t since the size of a size_t can vary between 32- and
-    memcpy(rects, mStorage.array(), mStorage.size() * sizeof(Rect));
+    // 64-bit processes
+    FlattenableUtils::write(buffer, size, static_cast<uint32_t>(mStorage.size()));
+    for (auto rect : mStorage) {
+        status_t result = rect.flatten(buffer, size);
+        if (result != NO_ERROR) {
+            return result;
+        }
+        FlattenableUtils::advance(buffer, size, sizeof(rect));
+    }
     return NO_ERROR;
 }
 
 status_t Region::unflatten(void const* buffer, size_t size) {
-    Region result;
+    if (size < sizeof(uint32_t)) {
-    if (size >= sizeof(Rect)) {
+        return NO_MEMORY;
-        Rect const* rects = reinterpret_cast<Rect const*>(buffer);
-        size_t count = size / sizeof(Rect);
-        if (count > 0) {
-            result.mStorage.clear();
-            ssize_t err = result.mStorage.insertAt(0, count);
-            if (err < 0) {
-                return status_t(err);
-            }
-            memcpy(result.mStorage.editArray(), rects, count*sizeof(Rect));
-        }
     }
+
+    uint32_t numRects = 0;
+    FlattenableUtils::read(buffer, size, numRects);
+    if (size < numRects * sizeof(Rect)) {
+        return NO_MEMORY;
+    }
+
+    Region result;
+    result.mStorage.clear();
+    for (size_t r = 0; r < numRects; ++r) {
+        Rect rect;
+        status_t status = rect.unflatten(buffer, size);
+        if (status != NO_ERROR) {
+            return status;
+        }
+        FlattenableUtils::advance(buffer, size, sizeof(rect));
+        result.mStorage.push_back(rect);
+    }
+
 #if VALIDATE_REGIONS
     validate(result, "Region::unflatten");
 #endif