Merge pull request #147 from morpho-labs/refactor/extsload

feat(extsload): expose generic storage getter

src/Blue.sol

@@ -300,4 +300,21 @@ contract Blue {
 
         return collateralValue.mulWadDown(market.lltv) >= borrowValue;
     }
+
+    // Storage view.
+
+    function extsload(bytes32[] calldata slots) external view returns (bytes32[] memory res) {
+        uint256 nSlots = slots.length;
+
+        res = new bytes32[](nSlots);
+
+        for (uint256 i; i < nSlots;) {
+            bytes32 slot = slots[i++];
+
+            /// @solidity memory-safe-assembly
+            assembly {
+                mstore(add(res, mul(i, 32)), sload(slot))
+            }
+        }
+    }
 }

test/forge/Blue.t.sol

@@ -685,6 +685,22 @@ contract BlueTest is Test {
 
         vm.stopPrank();
     }
+
+    function testExtsLoad(uint256 slot, bytes32 value0) public {
+        bytes32[] memory slots = new bytes32[](2);
+        slots[0] = bytes32(slot);
+        slots[1] = bytes32(slot / 2);
+
+        bytes32 value1 = keccak256(abi.encode(value0));
+        vm.store(address(blue), slots[0], value0);
+        vm.store(address(blue), slots[1], value1);
+
+        bytes32[] memory values = blue.extsload(slots);
+
+        assertEq(values.length, 2, "values.length");
+        assertEq(values[0], slot > 0 ? value0 : value1, "value0");
+        assertEq(values[1], value1, "value1");
+    }
 }
 
 function neq(Market memory a, Market memory b) pure returns (bool) {