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https://github.com/ethereum/go-ethereum.git
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c08048eb84
Silently masking the index with indexMask would let an oversized idx collide with emptyRef (makeRef(kindEmpty, 0)): e.g. makeRef(kindEmpty, 1<<30) returned emptyRef, which IsEmpty would accept as absent even though the caller meant to reference a real node. Panic instead. allocInternal/allocStem/allocHashed already panic on pool overflow, so this is a belt-and-suspenders guard for any direct callers.
56 lines
1.8 KiB
Go
56 lines
1.8 KiB
Go
// Copyright 2026 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 bintrie
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// nodeKind identifies the type of a trie node stored in a nodeRef.
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type nodeKind uint8
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const (
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kindEmpty nodeKind = iota
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kindInternal
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kindStem // up to 256 values per stem
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kindHashed
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)
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// nodeRef is a compact, GC-invisible reference to a node in a NodeStore.
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// It packs a 2-bit type tag (bits 31-30) and a 30-bit index (bits 29-0)
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// into a single uint32. Because nodeRef contains no Go pointers, slices
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// of structs containing nodeRef fields are allocated in noscan spans —
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// the garbage collector never examines them.
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type nodeRef uint32
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const (
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kindShift uint32 = 30
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indexMask uint32 = (1 << kindShift) - 1
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// emptyRef represents an empty node.
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emptyRef nodeRef = 0
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)
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func makeRef(kind nodeKind, idx uint32) nodeRef {
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if idx > indexMask {
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panic("nodeRef index overflow")
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}
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return nodeRef(uint32(kind)<<kindShift | idx)
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}
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func (r nodeRef) Kind() nodeKind { return nodeKind(uint32(r) >> kindShift) }
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// Index within the typed pool.
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func (r nodeRef) Index() uint32 { return uint32(r) & indexMask }
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func (r nodeRef) IsEmpty() bool { return r == emptyRef }
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