refactor: Clean up getFeePayer, mSourceBalance, and mPriorBalance (#6478)

This change:
* Introduces a new helper function on `STTx`, `getFeePayer`.
* Removes the usage of `mSourceBalance` and replaces it with SLE balance lookups.
* Renames `mPriorBalance` to `preFeeBalance_`

This simplifies some of the code in the transactors and makes it a lot more readable.

include/xrpl/protocol/STTx.h

@@ -83,6 +83,9 @@ public:
     std::uint32_t
     getSeqValue() const;
 
+    AccountID
+    getFeePayer() const;
+
     boost::container::flat_set<AccountID>
     getMentionedAccounts() const;
 

include/xrpl/tx/Transactor.h

@@ -114,8 +114,7 @@ protected:
     beast::Journal const j_;
 
     AccountID const account_;
-    XRPAmount mPriorBalance;   // Balance before fees.
-    XRPAmount mSourceBalance;  // Balance after fees.
+    XRPAmount preFeeBalance_;  // Balance before fees.
 
     virtual ~Transactor() = default;
     Transactor(Transactor const&) = delete;

src/libxrpl/protocol/STTx.cpp

@@ -211,6 +211,20 @@ STTx::getSeqValue() const
     return getSeqProxy().value();
 }
 
+AccountID
+STTx::getFeePayer() const
+{
+    // If sfDelegate is present, the delegate account is the payer
+    // note: if a delegate is specified, its authorization to act on behalf of the account is
+    // enforced in `Transactor::checkPermission`
+    // cryptographic signature validity is checked separately (e.g., in `Transactor::checkSign`)
+    if (isFieldPresent(sfDelegate))
+        return getAccountID(sfDelegate);
+
+    // Default payer
+    return getAccountID(sfAccount);
+}
+
 void
 STTx::sign(
     PublicKey const& publicKey,

src/libxrpl/tx/Transactor.cpp

@@ -352,8 +352,7 @@ Transactor::checkFee(PreclaimContext const& ctx, XRPAmount baseFee)
     if (feePaid == beast::zero)
         return tesSUCCESS;
 
-    auto const id = ctx.tx.isFieldPresent(sfDelegate) ? ctx.tx.getAccountID(sfDelegate)
-                                                      : ctx.tx.getAccountID(sfAccount);
+    auto const id = ctx.tx.getFeePayer();
     auto const sle = ctx.view.read(keylet::account(id));
     if (!sle)
         return terNO_ACCOUNT;
@@ -382,32 +381,18 @@ Transactor::payFee()
 {
     auto const feePaid = ctx_.tx[sfFee].xrp();
 
-    if (ctx_.tx.isFieldPresent(sfDelegate))
-    {
-        // Delegated transactions are paid by the delegated account.
-        auto const delegate = ctx_.tx.getAccountID(sfDelegate);
-        auto const delegatedSle = view().peek(keylet::account(delegate));
-        if (!delegatedSle)
-            return tefINTERNAL;  // LCOV_EXCL_LINE
+    auto const feePayer = ctx_.tx.getFeePayer();
+    auto const sle = view().peek(keylet::account(feePayer));
+    if (!sle)
+        return tefINTERNAL;  // LCOV_EXCL_LINE
 
-        delegatedSle->setFieldAmount(sfBalance, delegatedSle->getFieldAmount(sfBalance) - feePaid);
-        view().update(delegatedSle);
-    }
-    else
-    {
-        auto const sle = view().peek(keylet::account(account_));
-        if (!sle)
-            return tefINTERNAL;  // LCOV_EXCL_LINE
-
-        // Deduct the fee, so it's not available during the transaction.
-        // Will only write the account back if the transaction succeeds.
-
-        mSourceBalance -= feePaid;
-        sle->setFieldAmount(sfBalance, mSourceBalance);
-
-        // VFALCO Should we call view().rawDestroyXRP() here as well?
-    }
+    // Deduct the fee, so it's not available during the transaction.
+    // Will only write the account back if the transaction succeeds.
+    sle->setFieldAmount(sfBalance, sle->getFieldAmount(sfBalance) - feePaid);
+    if (feePayer != account_)
+        view().update(sle);  // done in `apply()` for the account
 
+    // VFALCO Should we call view().rawDestroyXRP() here as well?
     return tesSUCCESS;
 }
 
@@ -606,8 +591,7 @@ Transactor::apply()
 
     if (sle)
     {
-        mPriorBalance = STAmount{(*sle)[sfBalance]}.xrp();
-        mSourceBalance = mPriorBalance;
+        preFeeBalance_ = STAmount{(*sle)[sfBalance]}.xrp();
 
         TER result = consumeSeqProxy(sle);
         if (result != tesSUCCESS)
@@ -1023,9 +1007,7 @@ Transactor::reset(XRPAmount fee)
     if (!txnAcct)
         return {tefINTERNAL, beast::zero};
 
-    auto const payerSle = ctx_.tx.isFieldPresent(sfDelegate)
-        ? view().peek(keylet::account(ctx_.tx.getAccountID(sfDelegate)))
-        : txnAcct;
+    auto const payerSle = view().peek(keylet::account(ctx_.tx.getFeePayer()));
     if (!payerSle)
         return {tefINTERNAL, beast::zero};  // LCOV_EXCL_LINE
 

src/libxrpl/tx/transactors/account/DeleteAccount.cpp

@@ -371,9 +371,10 @@ DeleteAccount::doApply()
         return ter;
 
     // Transfer any XRP remaining after the fee is paid to the destination:
-    (*dst)[sfBalance] = (*dst)[sfBalance] + mSourceBalance;
-    (*src)[sfBalance] = (*src)[sfBalance] - mSourceBalance;
-    ctx_.deliver(mSourceBalance);
+    auto const remainingBalance = src->getFieldAmount(sfBalance).xrp();
+    (*dst)[sfBalance] = (*dst)[sfBalance] + remainingBalance;
+    (*src)[sfBalance] = (*src)[sfBalance] - remainingBalance;
+    ctx_.deliver(remainingBalance);
 
     XRPL_ASSERT(
         (*src)[sfBalance] == XRPAmount(0), "xrpl::DeleteAccount::doApply : source balance is zero");
@@ -387,7 +388,7 @@ DeleteAccount::doApply()
     }
 
     // Re-arm the password change fee if we can and need to.
-    if (mSourceBalance > XRPAmount(0) && dst->isFlag(lsfPasswordSpent))
+    if (remainingBalance > XRPAmount(0) && dst->isFlag(lsfPasswordSpent))
         dst->clearFlag(lsfPasswordSpent);
 
     view().update(dst);

src/libxrpl/tx/transactors/account/SetSignerList.cpp

@@ -306,7 +306,7 @@ SetSignerList::replaceSignerList()
     // We check the reserve against the starting balance because we want to
     // allow dipping into the reserve to pay fees.  This behavior is consistent
     // with CreateTicket.
-    if (mPriorBalance < newReserve)
+    if (preFeeBalance_ < newReserve)
         return tecINSUFFICIENT_RESERVE;
 
     // Everything's ducky.  Add the ltSIGNER_LIST to the ledger.

src/libxrpl/tx/transactors/bridge/XChainBridge.cpp

@@ -337,7 +337,7 @@ enum class DepositAuthPolicy { normal, dstCanBypass };
 struct TransferHelperSubmittingAccountInfo
 {
     AccountID account;
-    STAmount preFeeBalance;
+    STAmount preFeeBalance_;
     STAmount postFeeBalance;
 };
 
@@ -423,7 +423,7 @@ transferHelper(
                 if (!submittingAccountInfo || submittingAccountInfo->account != src ||
                     submittingAccountInfo->postFeeBalance != curBal)
                     return curBal;
-                return submittingAccountInfo->preFeeBalance;
+                return submittingAccountInfo->preFeeBalance_;
             }();
 
             if (availableBalance < amt + reserve)
@@ -1852,7 +1852,8 @@ XChainCommit::doApply()
     auto const amount = ctx_.tx[sfAmount];
     auto const bridgeSpec = ctx_.tx[sfXChainBridge];
 
-    if (!psb.read(keylet::account(account)))
+    auto const sleAccount = psb.read(keylet::account(account));
+    if (!sleAccount)
         return tecINTERNAL;  // LCOV_EXCL_LINE
 
     auto const sleBridge = readBridge(psb, bridgeSpec);
@@ -1863,7 +1864,7 @@ XChainCommit::doApply()
 
     // Support dipping into reserves to pay the fee
     TransferHelperSubmittingAccountInfo submittingAccountInfo{
-        account_, mPriorBalance, mSourceBalance};
+        account_, preFeeBalance_, (*sleAccount)[sfBalance]};
 
     auto const thTer = transferHelper(
         psb,
@@ -2132,7 +2133,7 @@ XChainCreateAccountCommit::doApply()
 
     // Support dipping into reserves to pay the fee
     TransferHelperSubmittingAccountInfo submittingAccountInfo{
-        account_, mPriorBalance, mSourceBalance};
+        account_, preFeeBalance_, (*sle)[sfBalance]};
     STAmount const toTransfer = amount + reward;
     auto const thTer = transferHelper(
         psb,

src/libxrpl/tx/transactors/check/CashCheck.cpp

@@ -309,7 +309,7 @@ CashCheck::doApply()
 
                 // Can the account cover the trust line's reserve?
                 if (std::uint32_t const ownerCount = {sleDst->at(sfOwnerCount)};
-                    mPriorBalance < psb.fees().accountReserve(ownerCount + 1))
+                    preFeeBalance_ < psb.fees().accountReserve(ownerCount + 1))
                 {
                     JLOG(j_.trace()) << "Trust line does not exist. "
                                         "Insufficent reserve to create line.";

src/libxrpl/tx/transactors/check/CreateCheck.cpp

@@ -140,7 +140,7 @@ CreateCheck::doApply()
     {
         STAmount const reserve{view().fees().accountReserve(sle->getFieldU32(sfOwnerCount) + 1)};
 
-        if (mPriorBalance < reserve)
+        if (preFeeBalance_ < reserve)
             return tecINSUFFICIENT_RESERVE;
     }
 

src/libxrpl/tx/transactors/credentials/CredentialAccept.cpp

@@ -85,7 +85,7 @@ CredentialAccept::doApply()
     {
         STAmount const reserve{
             view().fees().accountReserve(sleSubject->getFieldU32(sfOwnerCount) + 1)};
-        if (mPriorBalance < reserve)
+        if (preFeeBalance_ < reserve)
             return tecINSUFFICIENT_RESERVE;
     }
 

src/libxrpl/tx/transactors/credentials/CredentialCreate.cpp

@@ -117,7 +117,7 @@ CredentialCreate::doApply()
     {
         STAmount const reserve{
             view().fees().accountReserve(sleIssuer->getFieldU32(sfOwnerCount) + 1)};
-        if (mPriorBalance < reserve)
+        if (preFeeBalance_ < reserve)
             return tecINSUFFICIENT_RESERVE;
     }
 

src/libxrpl/tx/transactors/delegate/DelegateSet.cpp

@@ -70,7 +70,7 @@ DelegateSet::doApply()
     STAmount const reserve{
         ctx_.view().fees().accountReserve(sleOwner->getFieldU32(sfOwnerCount) + 1)};
 
-    if (mPriorBalance < reserve)
+    if (preFeeBalance_ < reserve)
         return tecINSUFFICIENT_RESERVE;
 
     auto const& permissions = ctx_.tx.getFieldArray(sfPermissions);

src/libxrpl/tx/transactors/dex/AMMClawback.cpp

@@ -172,7 +172,7 @@ AMMClawback::applyGuts(Sandbox& sb)
                 0,
                 FreezeHandling::fhIGNORE_FREEZE,
                 WithdrawAll::Yes,
-                mPriorBalance,
+                preFeeBalance_,
                 ctx_.journal);
     else
         std::tie(result, newLPTokenBalance, amountWithdraw, amount2Withdraw) =
@@ -251,7 +251,7 @@ AMMClawback::equalWithdrawMatchingOneAmount(
             0,
             FreezeHandling::fhIGNORE_FREEZE,
             WithdrawAll::Yes,
-            mPriorBalance,
+            preFeeBalance_,
             ctx_.journal);
 
     auto const& rules = sb.rules();
@@ -282,7 +282,7 @@ AMMClawback::equalWithdrawMatchingOneAmount(
             0,
             FreezeHandling::fhIGNORE_FREEZE,
             WithdrawAll::No,
-            mPriorBalance,
+            preFeeBalance_,
             ctx_.journal);
     }
 
@@ -301,7 +301,7 @@ AMMClawback::equalWithdrawMatchingOneAmount(
         0,
         FreezeHandling::fhIGNORE_FREEZE,
         WithdrawAll::No,
-        mPriorBalance,
+        preFeeBalance_,
         ctx_.journal);
 }
 

src/libxrpl/tx/transactors/dex/AMMWithdraw.cpp

@@ -414,7 +414,7 @@ AMMWithdraw::withdraw(
         tfee,
         FreezeHandling::fhZERO_IF_FROZEN,
         isWithdrawAll(ctx_.tx),
-        mPriorBalance,
+        preFeeBalance_,
         j_);
     return {ter, newLPTokenBalance};
 }
@@ -628,7 +628,7 @@ AMMWithdraw::equalWithdrawTokens(
         tfee,
         FreezeHandling::fhZERO_IF_FROZEN,
         isWithdrawAll(ctx_.tx),
-        mPriorBalance,
+        preFeeBalance_,
         ctx_.journal);
     return {ter, newLPTokenBalance};
 }

src/libxrpl/tx/transactors/dex/CreateOffer.cpp

@@ -727,7 +727,7 @@ CreateOffer::applyGuts(Sandbox& sb, Sandbox& sbCancel)
     {
         XRPAmount reserve = sb.fees().accountReserve(sleCreator->getFieldU32(sfOwnerCount) + 1);
 
-        if (mPriorBalance < reserve)
+        if (preFeeBalance_ < reserve)
         {
             // If we are here, the signing account had an insufficient reserve
             // *prior* to our processing. If something actually crossed, then

src/libxrpl/tx/transactors/escrow/EscrowCancel.cpp

@@ -164,7 +164,7 @@ EscrowCancel::doApply()
                         ctx_.view(),
                         parityRate,
                         slep,
-                        mPriorBalance,
+                        preFeeBalance_,
                         amount,
                         issuer,
                         account,  // sender and receiver are the same

src/libxrpl/tx/transactors/escrow/EscrowCreate.cpp

@@ -394,13 +394,14 @@ EscrowCreate::doApply()
 
     auto const reserve = ctx_.view().fees().accountReserve((*sle)[sfOwnerCount] + 1);
 
-    if (mSourceBalance < reserve)
+    auto const balance = sle->getFieldAmount(sfBalance).xrp();
+    if (balance < reserve)
         return tecINSUFFICIENT_RESERVE;
 
     // Check reserve and funds availability
     if (isXRP(amount))
     {
-        if (mSourceBalance < reserve + STAmount(amount).xrp())
+        if (balance < reserve + STAmount(amount).xrp())
             return tecUNFUNDED;
     }
 

src/libxrpl/tx/transactors/escrow/EscrowFinish.cpp

@@ -332,7 +332,7 @@ EscrowFinish::doApply()
                         ctx_.view(),
                         lockedRate,
                         sled,
-                        mPriorBalance,
+                        preFeeBalance_,
                         amount,
                         issuer,
                         account,

src/libxrpl/tx/transactors/lending/LoanBrokerCoverWithdraw.cpp

@@ -167,7 +167,7 @@ LoanBrokerCoverWithdraw::doApply()
 
     associateAsset(*broker, vaultAsset);
 
-    return doWithdraw(view(), tx, account_, dstAcct, brokerPseudoID, mPriorBalance, amount, j_);
+    return doWithdraw(view(), tx, account_, dstAcct, brokerPseudoID, preFeeBalance_, amount, j_);
 }
 
 //------------------------------------------------------------------------------

src/libxrpl/tx/transactors/lending/LoanBrokerSet.cpp

@@ -220,7 +220,7 @@ LoanBrokerSet::doApply()
         // one for the pseudo-account.
         adjustOwnerCount(view, owner, 2, j_);
         auto const ownerCount = owner->at(sfOwnerCount);
-        if (mPriorBalance < view.fees().accountReserve(ownerCount))
+        if (preFeeBalance_ < view.fees().accountReserve(ownerCount))
             return tecINSUFFICIENT_RESERVE;
 
         auto maybePseudo = createPseudoAccount(view, broker->key(), sfLoanBrokerID);
@@ -229,7 +229,7 @@ LoanBrokerSet::doApply()
         auto& pseudo = *maybePseudo;
         auto pseudoId = pseudo->at(sfAccount);
 
-        if (auto ter = addEmptyHolding(view, pseudoId, mPriorBalance, sleVault->at(sfAsset), j_))
+        if (auto ter = addEmptyHolding(view, pseudoId, preFeeBalance_, sleVault->at(sfAsset), j_))
             return ter;
 
         // Initialize data fields:

src/libxrpl/tx/transactors/lending/LoanSet.cpp

@@ -474,7 +474,7 @@ LoanSet::doApply()
     {
         auto const ownerCount = borrowerSle->at(sfOwnerCount);
         auto const balance =
-            account_ == borrower ? mPriorBalance : borrowerSle->at(sfBalance).value().xrp();
+            account_ == borrower ? preFeeBalance_ : borrowerSle->at(sfBalance).value().xrp();
         if (balance < view.fees().accountReserve(ownerCount))
             return tecINSUFFICIENT_RESERVE;
     }

src/libxrpl/tx/transactors/nft/NFTokenAcceptOffer.cpp

@@ -361,7 +361,7 @@ NFTokenAcceptOffer::transferNFToken(
     // NFTs free of reserve.
     if (view().rules().enabled(fixNFTokenReserve))
     {
-        // To check if there is sufficient reserve, we cannot use mPriorBalance
+        // To check if there is sufficient reserve, we cannot use preFeeBalance_
         // because NFT is sold for a price. So we must use the balance after
         // the deduction of the potential offer price. A small caveat here is
         // that the balance has already deducted the transaction fee, meaning

src/libxrpl/tx/transactors/nft/NFTokenCreateOffer.cpp

@@ -74,7 +74,7 @@ NFTokenCreateOffer::doApply()
         ctx_.tx[~sfExpiration],
         ctx_.tx.getSeqProxy(),
         ctx_.tx[sfNFTokenID],
-        mPriorBalance,
+        preFeeBalance_,
         j_,
         ctx_.tx.getFlags());
 }

src/libxrpl/tx/transactors/nft/NFTokenMint.cpp

@@ -293,7 +293,7 @@ NFTokenMint::doApply()
                 ctx_.tx[~sfExpiration],
                 ctx_.tx.getSeqProxy(),
                 nftokenID,
-                mPriorBalance,
+                preFeeBalance_,
                 j_);
             !isTesSuccess(ter))
             return ter;
@@ -308,7 +308,7 @@ NFTokenMint::doApply()
         ownerCountAfter > ownerCountBefore)
     {
         if (auto const reserve = view().fees().accountReserve(ownerCountAfter);
-            mPriorBalance < reserve)
+            preFeeBalance_ < reserve)
             return tecINSUFFICIENT_RESERVE;
     }
     return tesSUCCESS;

src/libxrpl/tx/transactors/payment/DepositPreauth.cpp

@@ -147,7 +147,7 @@ DepositPreauth::doApply()
             STAmount const reserve{
                 view().fees().accountReserve(sleOwner->getFieldU32(sfOwnerCount) + 1)};
 
-            if (mPriorBalance < reserve)
+            if (preFeeBalance_ < reserve)
                 return tecINSUFFICIENT_RESERVE;
         }
 
@@ -194,7 +194,7 @@ DepositPreauth::doApply()
             STAmount const reserve{
                 view().fees().accountReserve(sleOwner->getFieldU32(sfOwnerCount) + 1)};
 
-            if (mPriorBalance < reserve)
+            if (preFeeBalance_ < reserve)
                 return tecINSUFFICIENT_RESERVE;
         }
 

src/libxrpl/tx/transactors/payment/Payment.cpp

@@ -544,16 +544,16 @@ Payment::doApply()
     // This is the total reserve in drops.
     auto const reserve = view().fees().accountReserve(ownerCount);
 
-    // mPriorBalance is the balance on the sending account BEFORE the
+    // preFeeBalance_ is the balance on the sending account BEFORE the
     // fees were charged. We want to make sure we have enough reserve
     // to send. Allow final spend to use reserve for fee.
     auto const mmm = std::max(reserve, ctx_.tx.getFieldAmount(sfFee).xrp());
 
-    if (mPriorBalance < dstAmount.xrp() + mmm)
+    if (preFeeBalance_ < dstAmount.xrp() + mmm)
     {
         // Vote no. However the transaction might succeed, if applied in
         // a different order.
-        JLOG(j_.trace()) << "Delay transaction: Insufficient funds: " << to_string(mPriorBalance)
+        JLOG(j_.trace()) << "Delay transaction: Insufficient funds: " << to_string(preFeeBalance_)
                          << " / " << to_string(dstAmount.xrp() + mmm) << " (" << to_string(reserve)
                          << ")";
 
@@ -601,7 +601,7 @@ Payment::doApply()
     }
 
     // Do the arithmetic for the transfer and make the ledger change.
-    sleSrc->setFieldAmount(sfBalance, mSourceBalance - dstAmount);
+    sleSrc->setFieldAmount(sfBalance, sleSrc->getFieldAmount(sfBalance) - dstAmount);
     sleDst->setFieldAmount(sfBalance, sleDst->getFieldAmount(sfBalance) + dstAmount);
 
     // Re-arm the password change fee if we can and need to.

src/libxrpl/tx/transactors/system/CreateTicket.cpp

@@ -65,7 +65,7 @@ CreateTicket::doApply()
         XRPAmount const reserve =
             view().fees().accountReserve(sleAccountRoot->getFieldU32(sfOwnerCount) + ticketCount);
 
-        if (mPriorBalance < reserve)
+        if (preFeeBalance_ < reserve)
             return tecINSUFFICIENT_RESERVE;
     }
 

src/libxrpl/tx/transactors/token/MPTokenAuthorize.cpp

@@ -161,7 +161,7 @@ MPTokenAuthorize::doApply()
     auto const& tx = ctx_.tx;
     return authorizeMPToken(
         ctx_.view(),
-        mPriorBalance,
+        preFeeBalance_,
         tx[sfMPTokenIssuanceID],
         account_,
         ctx_.journal,

src/libxrpl/tx/transactors/token/MPTokenIssuanceCreate.cpp

@@ -138,7 +138,7 @@ MPTokenIssuanceCreate::doApply()
         view(),
         j_,
         {
-            .priorBalance = mPriorBalance,
+            .priorBalance = preFeeBalance_,
             .account = account_,
             .sequence = tx.getSeqValue(),
             .flags = tx.getFlags(),

src/libxrpl/tx/transactors/token/SetTrust.cpp

@@ -570,7 +570,7 @@ SetTrust::doApply()
             terResult = trustDelete(view(), sleRippleState, uLowAccountID, uHighAccountID, viewJ);
         }
         // Reserve is not scaled by load.
-        else if (bReserveIncrease && mPriorBalance < reserveCreate)
+        else if (bReserveIncrease && preFeeBalance_ < reserveCreate)
         {
             JLOG(j_.trace()) << "Delay transaction: Insufficent reserve to "
                                 "add trust line.";
@@ -598,8 +598,8 @@ SetTrust::doApply()
         JLOG(j_.trace()) << "Redundant: Setting non-existent ripple line to defaults.";
         return tecNO_LINE_REDUNDANT;
     }
-    else if (mPriorBalance < reserveCreate)  // Reserve is not scaled by
-                                             // load.
+    else if (preFeeBalance_ < reserveCreate)  // Reserve is not scaled by
+                                              // load.
     {
         JLOG(j_.trace()) << "Delay transaction: Line does not exist. "
                             "Insufficent reserve to create line.";

src/libxrpl/tx/transactors/vault/VaultCreate.cpp

@@ -137,7 +137,7 @@ VaultCreate::doApply()
     // We will create Vault and PseudoAccount, hence increase OwnerCount by 2
     adjustOwnerCount(view(), owner, 2, j_);
     auto const ownerCount = owner->at(sfOwnerCount);
-    if (mPriorBalance < view().fees().accountReserve(ownerCount))
+    if (preFeeBalance_ < view().fees().accountReserve(ownerCount))
         return tecINSUFFICIENT_RESERVE;
 
     auto maybePseudo = createPseudoAccount(view(), vault->key(), sfVaultID);
@@ -147,7 +147,7 @@ VaultCreate::doApply()
     auto pseudoId = pseudo->at(sfAccount);
     auto asset = tx[sfAsset];
 
-    if (auto ter = addEmptyHolding(view(), pseudoId, mPriorBalance, asset, j_); !isTesSuccess(ter))
+    if (auto ter = addEmptyHolding(view(), pseudoId, preFeeBalance_, asset, j_); !isTesSuccess(ter))
         return ter;
 
     std::uint8_t const scale = (asset.holds<MPTIssue>() || asset.native())
@@ -206,7 +206,7 @@ VaultCreate::doApply()
 
     // Explicitly create MPToken for the vault owner
     if (auto const err =
-            authorizeMPToken(view(), mPriorBalance, mptIssuanceID, account_, ctx_.journal);
+            authorizeMPToken(view(), preFeeBalance_, mptIssuanceID, account_, ctx_.journal);
         !isTesSuccess(err))
         return err;
 
@@ -214,7 +214,7 @@ VaultCreate::doApply()
     if (txFlags & tfVaultPrivate)
     {
         if (auto const err = authorizeMPToken(
-                view(), mPriorBalance, mptIssuanceID, pseudoId, ctx_.journal, {}, account_);
+                view(), preFeeBalance_, mptIssuanceID, pseudoId, ctx_.journal, {}, account_);
             !isTesSuccess(err))
             return err;
     }

src/libxrpl/tx/transactors/vault/VaultDeposit.cpp

@@ -146,7 +146,7 @@ VaultDeposit::doApply()
     if (vault->isFlag(lsfVaultPrivate) && account_ != vault->at(sfOwner))
     {
         if (auto const err = enforceMPTokenAuthorization(
-                ctx_.view(), mptIssuanceID, account_, mPriorBalance, j_);
+                ctx_.view(), mptIssuanceID, account_, preFeeBalance_, j_);
             !isTesSuccess(err))
             return err;
     }
@@ -156,7 +156,7 @@ VaultDeposit::doApply()
         if (!view().exists(keylet::mptoken(mptIssuanceID, account_)))
         {
             if (auto const err = authorizeMPToken(
-                    view(), mPriorBalance, mptIssuanceID->value(), account_, ctx_.journal);
+                    view(), preFeeBalance_, mptIssuanceID->value(), account_, ctx_.journal);
                 !isTesSuccess(err))
                 return err;
         }
@@ -169,7 +169,7 @@ VaultDeposit::doApply()
                 account_ == vault->at(sfOwner), "xrpl::VaultDeposit::doApply : account is owner");
             if (auto const err = authorizeMPToken(
                     view(),
-                    mPriorBalance,              // priorBalance
+                    preFeeBalance_,             // priorBalance
                     mptIssuanceID->value(),     // mptIssuanceID
                     sleIssuance->at(sfIssuer),  // account
                     ctx_.journal,

src/libxrpl/tx/transactors/vault/VaultWithdraw.cpp

@@ -230,7 +230,7 @@ VaultWithdraw::doApply()
     associateAsset(*vault, vaultAsset);
 
     return doWithdraw(
-        view(), ctx_.tx, account_, dstAcct, vaultAccount, mPriorBalance, assetsWithdrawn, j_);
+        view(), ctx_.tx, account_, dstAcct, vaultAccount, preFeeBalance_, assetsWithdrawn, j_);
 }
 
 }  // namespace xrpl