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https://github.com/ethereum/go-ethereum.git
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cf93077fab
The list iterator previously returned true on parse errors without advancing the input, which could lead to non-advancing infinite loops for callers that do not check Err() inside the loop; to make iteration safe while preserving error visibility, Next() now marks the iterator as finished when readKind fails, returning true for the error step so existing users that check Err() can handle it, and then false on subsequent calls, and the function comment was updated to document this behavior and the need to check Err().
68 lines
1.9 KiB
Go
68 lines
1.9 KiB
Go
// Copyright 2020 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package rlp
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type listIterator struct {
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data []byte
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next []byte
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err error
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}
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// NewListIterator creates an iterator for the (list) represented by data
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func NewListIterator(data RawValue) (*listIterator, error) {
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k, t, c, err := readKind(data)
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if err != nil {
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return nil, err
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}
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if k != List {
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return nil, ErrExpectedList
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}
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it := &listIterator{
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data: data[t : t+c],
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}
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return it, nil
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}
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// Next forwards the iterator one step.
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// Returns true if there is a next item or an error occurred on this step (check Err()).
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// On parse error, the iterator is marked finished and subsequent calls return false.
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func (it *listIterator) Next() bool {
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if len(it.data) == 0 {
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return false
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}
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_, t, c, err := readKind(it.data)
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if err != nil {
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it.next = nil
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it.err = err
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// Mark iteration as finished to avoid potential infinite loops on subsequent Next calls.
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it.data = nil
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return true
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}
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it.next = it.data[:t+c]
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it.data = it.data[t+c:]
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it.err = nil
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return true
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}
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// Value returns the current value
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func (it *listIterator) Value() []byte {
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return it.next
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}
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func (it *listIterator) Err() error {
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return it.err
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}
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