225 lines
6.7 KiB
Go
225 lines
6.7 KiB
Go
// Copyright 2014 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 trie
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import (
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"fmt"
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"io"
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"strings"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/rlp"
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)
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var indices = []string{"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f", "[17]"}
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type node interface {
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fstring(string) string
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cache() (hashNode, bool)
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canUnload(cachegen, cachelimit uint16) bool
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}
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type (
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fullNode struct {
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Children [17]node // Actual trie node data to encode/decode (needs custom encoder)
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flags nodeFlag
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}
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shortNode struct {
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Key []byte
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Val node
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flags nodeFlag
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}
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hashNode []byte
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valueNode []byte
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)
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// EncodeRLP encodes a full node into the consensus RLP format.
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func (n *fullNode) EncodeRLP(w io.Writer) error {
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return rlp.Encode(w, n.Children)
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}
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func (n *fullNode) copy() *fullNode { copy := *n; return © }
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func (n *shortNode) copy() *shortNode { copy := *n; return © }
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// nodeFlag contains caching-related metadata about a node.
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type nodeFlag struct {
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hash hashNode // cached hash of the node (may be nil)
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gen uint16 // cache generation counter
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dirty bool // whether the node has changes that must be written to the database
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}
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// canUnload tells whether a node can be unloaded.
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func (n *nodeFlag) canUnload(cachegen, cachelimit uint16) bool {
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return !n.dirty && cachegen-n.gen >= cachelimit
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}
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func (n *fullNode) canUnload(gen, limit uint16) bool { return n.flags.canUnload(gen, limit) }
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func (n *shortNode) canUnload(gen, limit uint16) bool { return n.flags.canUnload(gen, limit) }
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func (n hashNode) canUnload(uint16, uint16) bool { return false }
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func (n valueNode) canUnload(uint16, uint16) bool { return false }
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func (n *fullNode) cache() (hashNode, bool) { return n.flags.hash, n.flags.dirty }
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func (n *shortNode) cache() (hashNode, bool) { return n.flags.hash, n.flags.dirty }
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func (n hashNode) cache() (hashNode, bool) { return nil, true }
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func (n valueNode) cache() (hashNode, bool) { return nil, true }
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// Pretty printing.
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func (n *fullNode) String() string { return n.fstring("") }
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func (n *shortNode) String() string { return n.fstring("") }
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func (n hashNode) String() string { return n.fstring("") }
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func (n valueNode) String() string { return n.fstring("") }
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func (n *fullNode) fstring(ind string) string {
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resp := fmt.Sprintf("[\n%s ", ind)
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for i, node := range n.Children {
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if node == nil {
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resp += fmt.Sprintf("%s: <nil> ", indices[i])
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} else {
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resp += fmt.Sprintf("%s: %v", indices[i], node.fstring(ind+" "))
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}
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}
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return resp + fmt.Sprintf("\n%s] ", ind)
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}
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func (n *shortNode) fstring(ind string) string {
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return fmt.Sprintf("{%x: %v} ", n.Key, n.Val.fstring(ind+" "))
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}
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func (n hashNode) fstring(ind string) string {
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return fmt.Sprintf("<%x> ", []byte(n))
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}
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func (n valueNode) fstring(ind string) string {
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return fmt.Sprintf("%x ", []byte(n))
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}
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func mustDecodeNode(hash, buf []byte, cachegen uint16) node {
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n, err := decodeNode(hash, buf, cachegen)
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if err != nil {
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panic(fmt.Sprintf("node %x: %v", hash, err))
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}
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return n
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}
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// decodeNode parses the RLP encoding of a trie node.
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func decodeNode(hash, buf []byte, cachegen uint16) (node, error) {
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if len(buf) == 0 {
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return nil, io.ErrUnexpectedEOF
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}
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elems, _, err := rlp.SplitList(buf)
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if err != nil {
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return nil, fmt.Errorf("decode error: %v", err)
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}
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switch c, _ := rlp.CountValues(elems); c {
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case 2:
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n, err := decodeShort(hash, buf, elems, cachegen)
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return n, wrapError(err, "short")
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case 17:
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n, err := decodeFull(hash, buf, elems, cachegen)
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return n, wrapError(err, "full")
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default:
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return nil, fmt.Errorf("invalid number of list elements: %v", c)
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}
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}
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func decodeShort(hash, buf, elems []byte, cachegen uint16) (node, error) {
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kbuf, rest, err := rlp.SplitString(elems)
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if err != nil {
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return nil, err
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}
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flag := nodeFlag{hash: hash, gen: cachegen}
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key := compactDecode(kbuf)
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if key[len(key)-1] == 16 {
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// value node
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val, _, err := rlp.SplitString(rest)
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if err != nil {
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return nil, fmt.Errorf("invalid value node: %v", err)
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}
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return &shortNode{key, append(valueNode{}, val...), flag}, nil
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}
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r, _, err := decodeRef(rest, cachegen)
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if err != nil {
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return nil, wrapError(err, "val")
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}
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return &shortNode{key, r, flag}, nil
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}
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func decodeFull(hash, buf, elems []byte, cachegen uint16) (*fullNode, error) {
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n := &fullNode{flags: nodeFlag{hash: hash, gen: cachegen}}
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for i := 0; i < 16; i++ {
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cld, rest, err := decodeRef(elems, cachegen)
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if err != nil {
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return n, wrapError(err, fmt.Sprintf("[%d]", i))
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}
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n.Children[i], elems = cld, rest
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}
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val, _, err := rlp.SplitString(elems)
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if err != nil {
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return n, err
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}
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if len(val) > 0 {
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n.Children[16] = append(valueNode{}, val...)
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}
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return n, nil
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}
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const hashLen = len(common.Hash{})
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func decodeRef(buf []byte, cachegen uint16) (node, []byte, error) {
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kind, val, rest, err := rlp.Split(buf)
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if err != nil {
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return nil, buf, err
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}
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switch {
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case kind == rlp.List:
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// 'embedded' node reference. The encoding must be smaller
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// than a hash in order to be valid.
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if size := len(buf) - len(rest); size > hashLen {
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err := fmt.Errorf("oversized embedded node (size is %d bytes, want size < %d)", size, hashLen)
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return nil, buf, err
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}
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n, err := decodeNode(nil, buf, cachegen)
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return n, rest, err
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case kind == rlp.String && len(val) == 0:
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// empty node
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return nil, rest, nil
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case kind == rlp.String && len(val) == 32:
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return append(hashNode{}, val...), rest, nil
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default:
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return nil, nil, fmt.Errorf("invalid RLP string size %d (want 0 or 32)", len(val))
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}
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}
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// wraps a decoding error with information about the path to the
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// invalid child node (for debugging encoding issues).
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type decodeError struct {
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what error
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stack []string
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}
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func wrapError(err error, ctx string) error {
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if err == nil {
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return nil
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}
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if decErr, ok := err.(*decodeError); ok {
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decErr.stack = append(decErr.stack, ctx)
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return decErr
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}
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return &decodeError{err, []string{ctx}}
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}
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func (err *decodeError) Error() string {
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return fmt.Sprintf("%v (decode path: %s)", err.what, strings.Join(err.stack, "<-"))
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}
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