// Copyright 2015 The go-ethereum Authors // This file is part of the go-ethereum library. // // The go-ethereum library is free software: you can redistribute it and/or modify // it under the terms of the GNU Lesser General Public License as published by // the Free Software Foundation, either version 3 of the License, or // (at your option) any later version. // // The go-ethereum library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU Lesser General Public License for more details. // // You should have received a copy of the GNU Lesser General Public License // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. package state import ( "bytes" "fmt" "github.com/ethereum/go-ethereum/common" "github.com/ethereum/go-ethereum/rlp" "github.com/ethereum/go-ethereum/trie" ) // NodeIterator is an iterator to traverse the entire state trie post-order, // including all of the contract code and contract state tries. type NodeIterator struct { state *StateDB // State being iterated stateIt trie.NodeIterator // Primary iterator for the global state trie dataIt trie.NodeIterator // Secondary iterator for the data trie of a contract accountHash common.Hash // Hash of the node containing the account codeHash common.Hash // Hash of the contract source code code []byte // Source code associated with a contract Hash common.Hash // Hash of the current entry being iterated (nil if not standalone) Parent common.Hash // Hash of the first full ancestor node (nil if current is the root) Error error // Failure set in case of an internal error in the iterator } // NewNodeIterator creates an post-order state node iterator. func NewNodeIterator(state *StateDB) *NodeIterator { return &NodeIterator{ state: state, } } // Next moves the iterator to the next node, returning whether there are any // further nodes. In case of an internal error this method returns false and // sets the Error field to the encountered failure. func (it *NodeIterator) Next() bool { // If the iterator failed previously, don't do anything if it.Error != nil { return false } // Otherwise step forward with the iterator and report any errors if err := it.step(); err != nil { it.Error = err return false } return it.retrieve() } // step moves the iterator to the next entry of the state trie. func (it *NodeIterator) step() error { // Abort if we reached the end of the iteration if it.state == nil { return nil } // Initialize the iterator if we've just started if it.stateIt == nil { it.stateIt = it.state.trie.NodeIterator(nil) } // If we had data nodes previously, we surely have at least state nodes if it.dataIt != nil { if cont := it.dataIt.Next(true); !cont { if it.dataIt.Error() != nil { return it.dataIt.Error() } it.dataIt = nil } return nil } // If we had source code previously, discard that if it.code != nil { it.code = nil return nil } // Step to the next state trie node, terminating if we're out of nodes if cont := it.stateIt.Next(true); !cont { if it.stateIt.Error() != nil { return it.stateIt.Error() } it.state, it.stateIt = nil, nil return nil } // If the state trie node is an internal entry, leave as is if !it.stateIt.Leaf() { return nil } // Otherwise we've reached an account node, initiate data iteration var account Account if err := rlp.Decode(bytes.NewReader(it.stateIt.LeafBlob()), &account); err != nil { return err } dataTrie, err := it.state.db.OpenStorageTrie(common.BytesToHash(it.stateIt.LeafKey()), account.Root) if err != nil { return err } it.dataIt = dataTrie.NodeIterator(nil) if !it.dataIt.Next(true) { it.dataIt = nil } if !bytes.Equal(account.CodeHash, emptyCodeHash) { it.codeHash = common.BytesToHash(account.CodeHash) addrHash := common.BytesToHash(it.stateIt.LeafKey()) it.code, err = it.state.db.ContractCode(addrHash, common.BytesToHash(account.CodeHash)) if err != nil { return fmt.Errorf("code %x: %v", account.CodeHash, err) } } it.accountHash = it.stateIt.Parent() return nil } // retrieve pulls and caches the current state entry the iterator is traversing. // The method returns whether there are any more data left for inspection. func (it *NodeIterator) retrieve() bool { // Clear out any previously set values it.Hash = common.Hash{} // If the iteration's done, return no available data if it.state == nil { return false } // Otherwise retrieve the current entry switch { case it.dataIt != nil: it.Hash, it.Parent = it.dataIt.Hash(), it.dataIt.Parent() if it.Parent == (common.Hash{}) { it.Parent = it.accountHash } case it.code != nil: it.Hash, it.Parent = it.codeHash, it.accountHash case it.stateIt != nil: it.Hash, it.Parent = it.stateIt.Hash(), it.stateIt.Parent() } return true }