Add function to clear transient storage array

cowprotocol · Feb 4, 2025 · badb2c3 · badb2c3
1 parent 8e9a70f
commit badb2c3
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Showing 3 changed files with 45 additions and 1 deletion.
diff --git a/src/mixin/TransientStorageArray.sol b/src/mixin/TransientStorageArray.sol
@@ -123,4 +123,13 @@ abstract contract TransientStorageArray {
             mstore(dataMemoryLocation, byteLength)
         }
     }
+
+    /// @notice Clear all the content of the transient storage array, leaving
+    /// in its stead an empty array
+    /// @dev The actual transient storage array content isn't actually reset to
+    /// zero bytes, however this data cannot be accessed and can be overwritten
+    /// at a later point
+    function clearTransientStorageArray() internal {
+        length = 0;
+    }
 }
diff --git a/test/mixin/TransientStorageArray.t.sol b/test/mixin/TransientStorageArray.t.sol
@@ -83,10 +83,22 @@ contract TransientStorageArrayTest is Test {
         checkRoundTrip(data);
     }
 
-    function testFuzz_canOverrideArray(bytes memory firstArray, bytes memory secondArray) private {
+    function testFuzz_canOverrideArray(bytes memory firstArray, bytes memory secondArray) external {
         assertEq(executor.storeTwiceAndRead(firstArray, secondArray), secondArray);
     }
 
+    function testFuzz_clearingDoesNotAffectFutureStore(bytes memory data) external {
+        assertEq(executor.storeClearAndRead(data), hex"");
+    }
+
+    function testFuzz_clearedArrayHasZeroLength(bytes memory data) external {
+        assertEq(executor.storeClearReturnLength(data), 0);
+    }
+
+    function testFuzz_clearingDoesNotAffectFutureStore(bytes memory firstArray, bytes memory secondArray) external {
+        assertEq(executor.storeClearStoreAndRead(firstArray, secondArray), secondArray);
+    }
+
     function testFuzz_settingTransientVariablesDoesNotChangeArray(bytes memory data) external {
         BusyStoreAndRead busyExecutor = new BusyStoreAndRead(new BusyTransientStorage());
         assertEq(busyExecutor.storePopulateAndRead(data), data);

diff --git a/test/mixin/TransientStorageArray/ExposedTransientStorageArray.sol b/test/mixin/TransientStorageArray/ExposedTransientStorageArray.sol
@@ -18,6 +18,10 @@ contract ExposedTransientStorageArray is TransientStorageArray {
     function length() external view returns (uint256) {
         return transientStorageArrayLength();
     }
+
+    function clear() external {
+        clearTransientStorageArray();
+    }
 }
 
 uint256 constant BYTES_IN_WORD = 32;
@@ -50,6 +54,25 @@ contract StoreAndRead {
         return tsa.read();
     }
 
+    function storeClearReturnLength(bytes memory data) external returns (uint256) {
+        tsa.store(data);
+        tsa.clear();
+        return tsa.length();
+    }
+
+    function storeClearAndRead(bytes memory data) external returns (bytes memory) {
+        tsa.store(data);
+        tsa.clear();
+        return tsa.read();
+    }
+
+    function storeClearStoreAndRead(bytes memory data1, bytes memory data2) external returns (bytes memory) {
+        tsa.store(data1);
+        tsa.clear();
+        tsa.store(data2);
+        return tsa.read();
+    }
+
     function checkLength(Vm vm, bytes memory data) external {
         vm.assertEq(tsa.length(), 0);
         tsa.store(data);