43 lines
		
	
	
		
			1.5 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
		
		
			
		
	
	
			43 lines
		
	
	
		
			1.5 KiB
		
	
	
	
		
			Go
		
	
	
	
	
	
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								// Copyright 2021 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 misc
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								import (
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									"errors"
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									"fmt"
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									"github.com/ethereum/go-ethereum/params"
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								)
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								// VerifyGaslimit verifies the header gas limit according increase/decrease
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								// in relation to the parent gas limit.
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								func VerifyGaslimit(parentGasLimit, headerGasLimit uint64) error {
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									// Verify that the gas limit remains within allowed bounds
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									diff := int64(parentGasLimit) - int64(headerGasLimit)
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									if diff < 0 {
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										diff *= -1
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									}
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									limit := parentGasLimit / params.GasLimitBoundDivisor
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									if uint64(diff) >= limit {
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										return fmt.Errorf("invalid gas limit: have %d, want %d +-= %d", headerGasLimit, parentGasLimit, limit-1)
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									}
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									if headerGasLimit < params.MinGasLimit {
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										return errors.New("invalid gas limit below 5000")
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									}
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									return nil
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								}
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