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

2 files changed, 35 insertions, 16 deletions

diff --git a/libs/ui/Fence.cpp b/libs/ui/Fence.cpp
index 9cf2881787..bf24ffb7e0 100644
--- a/libs/ui/Fence.cpp
+++ b/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--;
diff --git a/libs/ui/Region.cpp b/libs/ui/Region.cpp
index 91fa21626f..23503b118f 100644
--- a/libs/ui/Region.cpp
+++ b/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);
-    memcpy(rects, mStorage.array(), mStorage.size() * sizeof(Rect));
+    // 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>(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) {
+    if (size < sizeof(uint32_t)) {
+        return NO_MEMORY;
+    }
+
+    uint32_t numRects = 0;
+    FlattenableUtils::read(buffer, size, numRects);
+    if (size < numRects * sizeof(Rect)) {
+        return NO_MEMORY;
+    }
+
     Region result;
-    if (size >= sizeof(Rect)) {
-        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));
+    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