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Fix transferFrom function so that we only delete token balances after we've verified the funds are available first - not before

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Signed-off-by: Rob Evans <robevansuk@noreply.users.github.io>
This commit is contained in:
Rob Evans 2023-06-22 00:36:08 +01:00
parent 7671bdd7c6
commit 074c5dc237
1 changed files with 48 additions and 28 deletions
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30
token-erc-1155/chaincode-go/chaincode/contract.go
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@ -9,6 +9,7 @@ package chaincode
import (
"encoding/json"
"fmt"
"github.com/hyperledger/fabric-protos-go/ledger/queryresult"
"sort"
"strconv"
"strings"
@ -949,6 +950,8 @@ func removeBalance(ctx contractapi.TransactionContextInterface, sender string, i
}
defer balanceIterator.Close()
var deferredDeletions = []func() error{}
// Iterate over keys that store balances and add them to partialBalance until
// either the necessary amount is reached or the keys ended
for balanceIterator.HasNext() && partialBalance < neededAmount {
@ -972,16 +975,22 @@ func removeBalance(ctx contractapi.TransactionContextInterface, sender string, i
selfRecipientKeyNeedsToBeRemoved = true
selfRecipientKey = queryResponse.Key
} else {
err = ctx.GetStub().DelState(queryResponse.Key)
if err != nil {
return fmt.Errorf("failed to delete the state of %v: %v", queryResponse.Key, err)
}
deferredDeletions = append(deferredDeletions, deferredDelete(ctx, queryResponse))
}
}
if partialBalance < neededAmount {
return fmt.Errorf("sender has insufficient funds for token %v, needed funds: %v, available fund: %v", tokenId, neededAmount, partialBalance)
} else if partialBalance > neededAmount {
} else {
// enough token funds have been found to perform the update
// now we can delete the token entries to supply updated token balances
for _, deleteFn := range deferredDeletions {
err := deleteFn()
if err != nil {
return err
}
}
if partialBalance > neededAmount {
// Send the remainder back to the sender
remainder, err := sub(partialBalance, neededAmount)
if err != nil {
@ -1009,10 +1018,21 @@ func removeBalance(ctx contractapi.TransactionContextInterface, sender string, i
}
}
}
}
return nil
}
func deferredDelete(ctx contractapi.TransactionContextInterface, queryResponse *queryresult.KV) func() error {
return func() error {
err := ctx.GetStub().DelState(queryResponse.Key)
if err != nil {
return fmt.Errorf("failed to delete the state of %v: %v", queryResponse.Key, err)
}
return nil
}
}
func emitTransferSingle(ctx contractapi.TransactionContextInterface, transferSingleEvent TransferSingle) error {
transferSingleEventJSON, err := json.Marshal(transferSingleEvent)
if err != nil {