♻️ ReentrancyGuard: avoid using magic numbers and initialize slot ins…

…ide of constructor (#785)
Vectorized · Jan 9, 2024 · 45ca1e6 · 45ca1e6
1 parent b2a5a8f
commit 45ca1e6
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Showing 2 changed files with 30 additions and 9 deletions.
diff --git a/.gas-snapshot b/.gas-snapshot
@@ -938,11 +938,11 @@ RedBlackTreeLibTest:testRedBlackTreeValues(uint256) (runs: 256, μ: 266948, ~: 2
 RedBlackTreeLibTest:test__codesize() (gas: 14795)
 ReentrancyGuardTest:testRecursiveDirectUnguardedCall() (gas: 34256)
 ReentrancyGuardTest:testRecursiveIndirectUnguardedCall() (gas: 47773)
-ReentrancyGuardTest:testRevertGuardLocked() (gas: 53925)
-ReentrancyGuardTest:testRevertReadGuardLocked() (gas: 53626)
-ReentrancyGuardTest:testRevertRecursiveDirectGuardedCall() (gas: 55173)
-ReentrancyGuardTest:testRevertRecursiveIndirectGuardedCall() (gas: 56579)
-ReentrancyGuardTest:testRevertRemoteCallback() (gas: 56213)
+ReentrancyGuardTest:testRevertGuardLocked() (gas: 36825)
+ReentrancyGuardTest:testRevertReadGuardLocked() (gas: 36526)
+ReentrancyGuardTest:testRevertRecursiveDirectGuardedCall() (gas: 38073)
+ReentrancyGuardTest:testRevertRecursiveIndirectGuardedCall() (gas: 39479)
+ReentrancyGuardTest:testRevertRemoteCallback() (gas: 39113)
 ReentrancyGuardTest:test__codesize() (gas: 5563)
 SSTORE2Test:testReadInvalidPointerCustomBoundsReverts() (gas: 3242)
 SSTORE2Test:testReadInvalidPointerCustomBoundsReverts(address,uint256,uint256) (runs: 256, μ: 832570, ~: 629512)

diff --git a/src/utils/ReentrancyGuard.sol b/src/utils/ReentrancyGuard.sol
@@ -11,6 +11,16 @@ abstract contract ReentrancyGuard {
     /// @dev Unauthorized reentrant call.
     error Reentrancy();
 
+    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
+    /*                         CONSTANTS                          */
+    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/
+
+    /// @dev The non-reentrancy flag.
+    uint256 private constant _NOT_ENTERED = 1;
+
+    /// @dev The reentrancy flag.
+    uint256 private constant _ENTERED = 2;
+
     /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
     /*                          STORAGE                           */
     /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/
@@ -20,6 +30,17 @@ abstract contract ReentrancyGuard {
     /// but not too large to result in excessive bytecode bloat.
     uint256 private constant _REENTRANCY_GUARD_SLOT = 0x929eee149b4bd21268;
 
+    /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
+    /*                        CONSTRUCTOR                         */
+    /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/
+
+    constructor() {
+        /// @solidity memory-safe-assembly
+        assembly {
+            sstore(_REENTRANCY_GUARD_SLOT, _NOT_ENTERED)
+        }
+    }
+
     /*´:°•.°+.*•´.*:˚.°*.˚•´.°:°•.°•.*•´.*:˚.°*.˚•´.°:°•.°+.*•´.*:*/
     /*                      REENTRANCY GUARD                      */
     /*.•°:°.´+˚.*°.˚:*.´•*.+°.•°:´*.´•*.•°.•°:°.´:•˚°.*°.˚:*.´+°.•*/
@@ -28,24 +49,24 @@ abstract contract ReentrancyGuard {
     modifier nonReentrant() virtual {
         /// @solidity memory-safe-assembly
         assembly {
-            if eq(sload(_REENTRANCY_GUARD_SLOT), 2) {
+            if eq(sload(_REENTRANCY_GUARD_SLOT), _ENTERED) {
                 mstore(0x00, 0xab143c06) // `Reentrancy()`.
                 revert(0x1c, 0x04)
             }
-            sstore(_REENTRANCY_GUARD_SLOT, 2)
+            sstore(_REENTRANCY_GUARD_SLOT, _ENTERED)
         }
         _;
         /// @solidity memory-safe-assembly
         assembly {
-            sstore(_REENTRANCY_GUARD_SLOT, 1)
+            sstore(_REENTRANCY_GUARD_SLOT, _NOT_ENTERED)
         }
     }
 
     /// @dev Guards a view function from read-only reentrancy.
     modifier nonReadReentrant() virtual {
         /// @solidity memory-safe-assembly
         assembly {
-            if eq(sload(_REENTRANCY_GUARD_SLOT), 2) {
+            if eq(sload(_REENTRANCY_GUARD_SLOT), _ENTERED) {
                 mstore(0x00, 0xab143c06) // `Reentrancy()`.
                 revert(0x1c, 0x04)
             }