github.com/ethereum/go-ethereum@v1.14.3/consensus/misc/gaslimit.go (about)

     1  // Copyright 2021 The go-ethereum Authors
     2  // This file is part of the go-ethereum library.
     3  //
     4  // The go-ethereum library is free software: you can redistribute it and/or modify
     5  // it under the terms of the GNU Lesser General Public License as published by
     6  // the Free Software Foundation, either version 3 of the License, or
     7  // (at your option) any later version.
     8  //
     9  // The go-ethereum library is distributed in the hope that it will be useful,
    10  // but WITHOUT ANY WARRANTY; without even the implied warranty of
    11  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    12  // GNU Lesser General Public License for more details.
    13  //
    14  // You should have received a copy of the GNU Lesser General Public License
    15  // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package misc
    18  
    19  import (
    20  	"fmt"
    21  
    22  	"github.com/ethereum/go-ethereum/params"
    23  )
    24  
    25  // VerifyGaslimit verifies the header gas limit according increase/decrease
    26  // in relation to the parent gas limit.
    27  func VerifyGaslimit(parentGasLimit, headerGasLimit uint64) error {
    28  	// Verify that the gas limit remains within allowed bounds
    29  	diff := int64(parentGasLimit) - int64(headerGasLimit)
    30  	if diff < 0 {
    31  		diff *= -1
    32  	}
    33  	limit := parentGasLimit / params.GasLimitBoundDivisor
    34  	if uint64(diff) >= limit {
    35  		return fmt.Errorf("invalid gas limit: have %d, want %d +-= %d", headerGasLimit, parentGasLimit, limit-1)
    36  	}
    37  	if headerGasLimit < params.MinGasLimit {
    38  		return fmt.Errorf("invalid gas limit below %d", params.MinGasLimit)
    39  	}
    40  	return nil
    41  }