[scudo] Use template specialization on Quarantine to avoid zero-length array am: c69ff27cfb am: f603b0128e am: 77f8306724 am: 1918656fbb

Original change: https://android-review.googlesource.com/c/platform/external/scudo/+/2066948

Change-Id: I57db8b57b6f8393043416b3a476a0429598a1fb7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

1 files changed, 15 insertions, 1 deletions

diff --git a/standalone/secondary.h b/standalone/secondary.h
index abb58a2882a..f0468391dee 100644
--- a/standalone/secondary.h
+++ b/standalone/secondary.h
@@ -113,6 +113,19 @@ void mapSecondary(Options Options, uptr CommitBase, uptr CommitSize,
   }
 }
 
+// Template specialization to avoid producing zero-length array
+template <typename T, size_t Size> class NonZeroLengthArray {
+public:
+  T &operator[](uptr Idx) { return values[Idx]; }
+
+private:
+  T values[Size];
+};
+template <typename T> class NonZeroLengthArray<T, 0> {
+public:
+  T &operator[](uptr UNUSED Idx) { UNREACHABLE("Unsupported!"); }
+};
+
 template <typename Config> class MapAllocatorCache {
 public:
   // Ensure the default maximum specified fits the array.
@@ -395,7 +408,8 @@ private:
   atomic_s32 ReleaseToOsIntervalMs = {};
 
   CachedBlock Entries[Config::SecondaryCacheEntriesArraySize] = {};
-  CachedBlock Quarantine[Config::SecondaryCacheQuarantineSize] = {};
+  NonZeroLengthArray<CachedBlock, Config::SecondaryCacheQuarantineSize>
+      Quarantine = {};
 };
 
 template <typename Config> class MapAllocator {