Make ERC777 operator the caller (#2134)

* Make the sender the operator

* Make hook methods private

* Add changelog entry

CHANGELOG.md

@@ -22,6 +22,8 @@
  * `Escrow`, `ConditionalEscrow`, `RefundEscrow`: these now use `Ownable` instead of `Secondary`, their external API changed accordingly. ([#2120](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2120))
  * `ERC20`: removed `_burnFrom`. ([#2119](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2119))
  * `Address`: removed `toPayable`, use `payable(address)` instead. ([#2133](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2133))
+ * `ERC777`: `_send`, `_mint` and `_burn` now use the caller as the operator. ([#2134](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2134))
+ * `ERC777`: removed `_callsTokensToSend` and `_callTokensReceived`. ([#2134](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/2134))
 
 ## 2.5.0 (2020-02-04)
 

contracts/mocks/ERC777Mock.sol

@@ -11,16 +11,15 @@ contract ERC777Mock is Context, ERC777 {
         string memory symbol,
         address[] memory defaultOperators
     ) public ERC777(name, symbol, defaultOperators) {
-        _mint(_msgSender(), initialHolder, initialBalance, "", "");
+        _mint(initialHolder, initialBalance, "", "");
     }
 
     function mintInternal (
-        address operator,
         address to,
         uint256 amount,
         bytes memory userData,
         bytes memory operatorData
     ) public {
-        _mint(operator, to, amount, userData, operatorData);
+        _mint(to, amount, userData, operatorData);
     }
 }

contracts/token/ERC777/ERC777.sol

@@ -135,7 +135,7 @@ contract ERC777 is Context, IERC777, IERC20 {
      * Also emits a {IERC20-Transfer} event for ERC20 compatibility.
      */
     function send(address recipient, uint256 amount, bytes memory data) public override  {
-        _send(_msgSender(), _msgSender(), recipient, amount, data, "", true);
+        _send(_msgSender(), recipient, amount, data, "", true);
     }
 
     /**
@@ -166,7 +166,7 @@ contract ERC777 is Context, IERC777, IERC20 {
      * Also emits a {IERC20-Transfer} event for ERC20 compatibility.
      */
     function burn(uint256 amount, bytes memory data) public override  {
-        _burn(_msgSender(), _msgSender(), amount, data, "");
+        _burn(_msgSender(), amount, data, "");
     }
 
     /**
@@ -233,7 +233,7 @@ contract ERC777 is Context, IERC777, IERC20 {
     public override
     {
         require(isOperatorFor(_msgSender(), sender), "ERC777: caller is not an operator for holder");
-        _send(_msgSender(), sender, recipient, amount, data, operatorData, true);
+        _send(sender, recipient, amount, data, operatorData, true);
     }
 
     /**
@@ -243,7 +243,7 @@ contract ERC777 is Context, IERC777, IERC20 {
      */
     function operatorBurn(address account, uint256 amount, bytes memory data, bytes memory operatorData) public override {
         require(isOperatorFor(_msgSender(), account), "ERC777: caller is not an operator for holder");
-        _burn(_msgSender(), account, amount, data, operatorData);
+        _burn(account, amount, data, operatorData);
     }
 
     /**
@@ -311,7 +311,6 @@ contract ERC777 is Context, IERC777, IERC20 {
      * interface.
      */
     function _mint(
-        address operator,
         address account,
         uint256 amount,
         bytes memory userData,
@@ -321,6 +320,8 @@ contract ERC777 is Context, IERC777, IERC20 {
     {
         require(account != address(0), "ERC777: mint to the zero address");
 
+        address operator = _msgSender();
+
         // Update state variables
         _totalSupply = _totalSupply.add(amount);
         _balances[account] = _balances[account].add(amount);
@@ -333,7 +334,6 @@ contract ERC777 is Context, IERC777, IERC20 {
 
     /**
      * @dev Send tokens
-     * @param operator address operator requesting the transfer
      * @param from address token holder address
      * @param to address recipient address
      * @param amount uint256 amount of tokens to transfer
@@ -342,7 +342,6 @@ contract ERC777 is Context, IERC777, IERC20 {
      * @param requireReceptionAck if true, contract recipients are required to implement ERC777TokensRecipient
      */
     function _send(
-        address operator,
         address from,
         address to,
         uint256 amount,
@@ -355,6 +354,8 @@ contract ERC777 is Context, IERC777, IERC20 {
         require(from != address(0), "ERC777: send from the zero address");
         require(to != address(0), "ERC777: send to the zero address");
 
+        address operator = _msgSender();
+
         _callTokensToSend(operator, from, to, amount, userData, operatorData);
 
         _move(operator, from, to, amount, userData, operatorData);
@@ -364,14 +365,12 @@ contract ERC777 is Context, IERC777, IERC20 {
 
     /**
      * @dev Burn tokens
-     * @param operator address operator requesting the operation
      * @param from address token holder address
      * @param amount uint256 amount of tokens to burn
      * @param data bytes extra information provided by the token holder
      * @param operatorData bytes extra information provided by the operator (if any)
      */
     function _burn(
-        address operator,
         address from,
         uint256 amount,
         bytes memory data,
@@ -381,6 +380,8 @@ contract ERC777 is Context, IERC777, IERC20 {
     {
         require(from != address(0), "ERC777: burn from the zero address");
 
+        address operator = _msgSender();
+
         _callTokensToSend(operator, from, address(0), amount, data, operatorData);
 
         // Update state variables
@@ -437,7 +438,7 @@ contract ERC777 is Context, IERC777, IERC20 {
         bytes memory userData,
         bytes memory operatorData
     )
-        internal
+        private
     {
         address implementer = ERC1820_REGISTRY.getInterfaceImplementer(from, TOKENS_SENDER_INTERFACE_HASH);
         if (implementer != address(0)) {
@@ -465,7 +466,7 @@ contract ERC777 is Context, IERC777, IERC20 {
         bytes memory operatorData,
         bool requireReceptionAck
     )
-        internal
+        private
     {
         address implementer = ERC1820_REGISTRY.getInterfaceImplementer(to, TOKENS_RECIPIENT_INTERFACE_HASH);
         if (implementer != address(0)) {

test/token/ERC777/ERC777.behavior.js

@@ -281,7 +281,9 @@ function shouldBehaveLikeERC777InternalMint (recipient, operator, amount, data,
   shouldInternalMintTokens(operator, recipient, amount, data, operatorData);
 
   it('reverts when minting tokens for the zero address', async function () {
-    await expectRevert.unspecified(this.token.mintInternal(operator, ZERO_ADDRESS, amount, data, operatorData));
+    await expectRevert.unspecified(
+      this.token.mintInternal(ZERO_ADDRESS, amount, data, operatorData, { from: operator })
+    );
   });
 }
 
@@ -290,7 +292,7 @@ function shouldInternalMintTokens (operator, to, amount, data, operatorData) {
     const initialTotalSupply = await this.token.totalSupply();
     const initialToBalance = await this.token.balanceOf(to);
 
-    const { logs } = await this.token.mintInternal(operator, to, amount, data, operatorData);
+    const { logs } = await this.token.mintInternal(to, amount, data, operatorData, { from: operator });
 
     expectEvent.inLogs(logs, 'Minted', {
       operator,
@@ -332,7 +334,7 @@ function shouldBehaveLikeERC777SendBurnMintInternalWithReceiveHook (operator, am
 
     it('mint (internal) reverts', async function () {
       await expectRevert.unspecified(
-        this.token.mintInternal(operator, this.recipient, amount, data, operatorData)
+        this.token.mintInternal(this.recipient, amount, data, operatorData, { from: operator })
       );
     });
   });
@@ -387,7 +389,7 @@ function shouldBehaveLikeERC777SendBurnMintInternalWithReceiveHook (operator, am
 
     it('TokensRecipient receives mint (internal) data and is called after state mutation', async function () {
       const { tx } = await this.token.mintInternal(
-        operator, this.recipient, amount, data, operatorData,
+        this.recipient, amount, data, operatorData, { from: operator }
       );
 
       const postRecipientBalance = await this.token.balanceOf(this.recipient);

test/token/ERC777/ERC777.test.js

@@ -300,7 +300,7 @@ describe('ERC777', function () {
 
             it('mint (internal) reverts', async function () {
               await expectRevert(
-                this.token.mintInternal(operator, this.recipient, amount, data, operatorData),
+                this.token.mintInternal(this.recipient, amount, data, operatorData, { from: operator }),
                 'ERC777: token recipient contract has no implementer for ERC777TokensRecipient',
               );
             });