Merge pull request #4 from axieinfinity/feature/lib-error-handler

feat: add `LibErrorHandler`

src/LibErrorHandler.sol

@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.19;
+
+library LibErrorHandler {
+  /// @dev Reserves error definition to upload to signature database.
+  error ExternalCallFailed(bytes4 msgSig, bytes4 callSig);
+
+  /// @notice handle low level call revert if call failed,
+  /// If extcall return empty bytes, reverts with custom error.
+  /// @param status Status of external call
+  /// @param callSig function signature of the calldata
+  /// @param returnOrRevertData bytes result from external call
+  function handleRevert(bool status, bytes4 callSig, bytes memory returnOrRevertData) internal pure {
+    // Get the function signature of current context
+    bytes4 msgSig = msg.sig;
+    assembly ("memory-safe") {
+      if iszero(status) {
+        // Load the length of bytes array
+        let revertLength := mload(returnOrRevertData)
+        // Check if length != 0 => revert following reason from external call
+        if iszero(iszero(revertLength)) {
+          // Start of revert data bytes. The 0x20 offset is always the same.
+          revert(add(returnOrRevertData, 0x20), revertLength)
+        }
+
+        // Load free memory pointer
+        let ptr := mload(0x40)
+        // Store 4 bytes the function selector of ExternalCallFailed(msg.sig, callSig)
+        // Equivalent to revert ExternalCallFailed(bytes4,bytes4)
+        mstore(ptr, 0x49bf4104)
+        // Store 4 bytes of msgSig parameter in the next slot
+        mstore(add(ptr, 0x20), msgSig)
+        // Store 4 bytes of callSig parameter in the next slot
+        mstore(add(ptr, 0x40), callSig)
+        // Revert 68 bytes of error starting from 0x1c
+        revert(add(ptr, 0x1c), 0x44)
+      }
+    }
+  }
+}