From 7538b89730ccb503c3a5916e94cad10fcfe9b398 Mon Sep 17 00:00:00 2001
From: Skima Harvey <64636974+skimaharvey@users.noreply.github.com>
Date: Thu, 11 Jan 2024 09:14:00 +0000
Subject: [PATCH] fix: move _beforeTokenTransfer before balance check (#843)

---
 .../LSP7DigitalAsset/LSP7DigitalAssetCore.sol   | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/contracts/LSP7DigitalAsset/LSP7DigitalAssetCore.sol b/contracts/LSP7DigitalAsset/LSP7DigitalAssetCore.sol
index 99aa553aa..f396cd570 100644
--- a/contracts/LSP7DigitalAsset/LSP7DigitalAssetCore.sol
+++ b/contracts/LSP7DigitalAsset/LSP7DigitalAssetCore.sol
@@ -482,13 +482,12 @@ abstract contract LSP7DigitalAssetCore is ILSP7DigitalAsset {
             revert LSP7CannotSendWithAddressZero();
         }
 
+        _beforeTokenTransfer(from, address(0), amount, data);
+
         uint256 balance = _tokenOwnerBalances[from];
         if (amount > balance) {
             revert LSP7AmountExceedsBalance(balance, from, amount);
         }
-
-        _beforeTokenTransfer(from, address(0), amount, data);
-
         // tokens being burnt
         _existingTokens -= amount;
 
@@ -594,13 +593,13 @@ abstract contract LSP7DigitalAssetCore is ILSP7DigitalAsset {
             revert LSP7CannotSendWithAddressZero();
         }
 
+        _beforeTokenTransfer(from, to, amount, data);
+
         uint256 balance = _tokenOwnerBalances[from];
         if (amount > balance) {
             revert LSP7AmountExceedsBalance(balance, from, amount);
         }
 
-        _beforeTokenTransfer(from, to, amount, data);
-
         _tokenOwnerBalances[from] -= amount;
         _tokenOwnerBalances[to] += amount;
 
@@ -657,8 +656,8 @@ abstract contract LSP7DigitalAssetCore is ILSP7DigitalAsset {
      * @dev Attempt to notify the operator `operator` about the `amount` tokens being authorized with.
      * This is done by calling its {universalReceiver} function with the `_TYPEID_LSP7_TOKENOPERATOR` as typeId, if `operator` is a contract that supports the LSP1 interface.
      * If `operator` is an EOA or a contract that does not support the LSP1 interface, nothing will happen and no notification will be sent.
-     
-     * @param operator The address to call the {universalReceiver} function on.                                                                                                                                                                                   
+
+     * @param operator The address to call the {universalReceiver} function on.
      * @param lsp1Data the data to be sent to the `operator` address in the `universalReceiver` call.
      */
     function _notifyTokenOperator(
@@ -676,8 +675,8 @@ abstract contract LSP7DigitalAssetCore is ILSP7DigitalAsset {
      * @dev Attempt to notify the token sender `from` about the `amount` of tokens being transferred.
      * This is done by calling its {universalReceiver} function with the `_TYPEID_LSP7_TOKENSSENDER` as typeId, if `from` is a contract that supports the LSP1 interface.
      * If `from` is an EOA or a contract that does not support the LSP1 interface, nothing will happen and no notification will be sent.
-     
-     * @param from The address to call the {universalReceiver} function on.                                                                                                                                                                                   
+
+     * @param from The address to call the {universalReceiver} function on.
      * @param lsp1Data the data to be sent to the `from` address in the `universalReceiver` call.
      */
     function _notifyTokenSender(