feat: add ConversionHelpers lib for converting memory types

aragon · Mar 26, 2019 · 0281046 · 0281046
1 parent dca0b4b
commit 0281046
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Showing 4 changed files with 38 additions and 35 deletions.
diff --git a/contracts/acl/ACL.sol b/contracts/acl/ACL.sol
@@ -1,6 +1,7 @@
 pragma solidity 0.4.24;
 
 import "../apps/AragonApp.sol";
+import "../common/ConversionHelpers.sol";
 import "../common/TimeHelpers.sol";
 import "./ACLSyntaxSugar.sol";
 import "./IACL.sol";
@@ -242,17 +243,7 @@ contract ACL is IACL, TimeHelpers, AragonApp, ACLHelpers {
     * @return boolean indicating whether the ACL allows the role or not
     */
     function hasPermission(address _who, address _where, bytes32 _what, bytes memory _how) public view returns (bool) {
-        // Force cast the bytes array into a uint256[], by overwriting its length
-        // Note that the uint256[] doesn't need to be initialized as we immediately overwrite it
-        // with _how and a new length, and _how becomes invalid from this point forward
-        uint256[] memory how;
-        uint256 intsLength = _how.length / 32;
-        assembly {
-            how := _how
-            mstore(how, intsLength)
-        }
-
-        return hasPermission(_who, _where, _what, how);
+        return hasPermission(_who, _where, _what, ConversionHelpers.castBytesToUintArray(_how));
     }
 
     function hasPermission(address _who, address _where, bytes32 _what, uint256[] memory _how) public view returns (bool) {

diff --git a/contracts/apps/AragonApp.sol b/contracts/apps/AragonApp.sol
@@ -5,10 +5,11 @@
 pragma solidity ^0.4.24;
 
 import "./AppStorage.sol";
+import "../acl/ACLSyntaxSugar.sol";
 import "../common/Autopetrified.sol";
+import "../common/ConversionHelpers.sol";
 import "../common/VaultRecoverable.sol";
 import "../evmscript/EVMScriptRunner.sol";
-import "../acl/ACLSyntaxSugar.sol";
 
 
 // Contracts inheriting from AragonApp are, by default, immediately petrified upon deployment so
@@ -47,16 +48,7 @@ contract AragonApp is AppStorage, Autopetrified, VaultRecoverable, EVMScriptRunn
             return false;
         }
 
-        // Force cast the uint256[] into a bytes array, by overwriting its length
-        // Note that the bytes array doesn't need to be initialized as we immediately overwrite it
-        // with _params and a new length, and _params becomes invalid from this point forward
-        bytes memory how;
-        uint256 byteLength = _params.length * 32;
-        assembly {
-            how := _params
-            mstore(how, byteLength)
-        }
-        return linkedKernel.hasPermission(_sender, address(this), _role, how);
+        return linkedKernel.hasPermission(_sender, address(this), _role, ConversionHelpers.castUintArrayToBytes(_params));
     }
 
     /**

diff --git a/contracts/common/ConversionHelpers.sol b/contracts/common/ConversionHelpers.sol
@@ -0,0 +1,26 @@
+pragma solidity ^0.4.24;
+
+
+library ConversionHelpers {
+    function castUintArrayToBytes(uint256[] memory _input) internal pure returns (bytes memory output) {
+        // Force cast the uint256[] into a bytes array, by overwriting its length
+        // Note that the bytes array doesn't need to be initialized as we immediately overwrite it
+        // with the input and a new length. The input becomes invalid from this point forward.
+        uint256 byteLength = _input.length * 32;
+        assembly {
+            output := _input
+            mstore(output, byteLength)
+        }
+    }
+
+    function castBytesToUintArray(bytes memory _input) internal pure returns (uint256[] memory output) {
+        // Force cast the bytes array into a uint256[], by overwriting its length
+        // Note that the uint256[] doesn't need to be initialized as we immediately overwrite it
+        // with the input and a new length. The input becomes invalid from this point forward.
+        uint256 intsLength = _input.length / 32;
+        assembly {
+            output := _input
+            mstore(output, intsLength)
+        }
+    }
+}
diff --git a/contracts/kernel/Kernel.sol b/contracts/kernel/Kernel.sol
@@ -5,11 +5,12 @@ import "./KernelConstants.sol";
 import "./KernelStorage.sol";
 import "../acl/IACL.sol";
 import "../acl/ACLSyntaxSugar.sol";
-import "../lib/misc/ERCProxy.sol";
+import "../common/ConversionHelpers.sol";
 import "../common/IsContract.sol";
 import "../common/Petrifiable.sol";
 import "../common/VaultRecoverable.sol";
 import "../factory/AppProxyFactory.sol";
+import "../lib/misc/ERCProxy.sol";
 
 
 // solium-disable-next-line max-len
@@ -227,18 +228,11 @@ contract Kernel is IKernel, KernelStorage, KernelAppIds, KernelNamespaceConstant
         }
     }
 
-    modifier auth(bytes32 _role, uint256[] memory params) {
-        // Force cast the uint256[] into a bytes array, by overwriting its length
-        // Note that the bytes array doesn't need to be initialized as we immediately overwrite it
-        // with params and a new length, and params becomes invalid from this point forward
-        bytes memory how;
-        uint256 byteLength = params.length * 32;
-        assembly {
-            how := params
-            mstore(how, byteLength)
-        }
-
-        require(hasPermission(msg.sender, address(this), _role, how), ERROR_AUTH_FAILED);
+    modifier auth(bytes32 _role, uint256[] memory _params) {
+        require(
+            hasPermission(msg.sender, address(this), _role, ConversionHelpers.castUintArrayToBytes(_params)),
+            ERROR_AUTH_FAILED
+        );
         _;
     }
 }