github.com/SmartMeshFoundation/Spectrum@v0.0.0-20220621030607-452a266fee1e/core/evm.go (about)

     1  // Copyright 2016 The Spectrum Authors
     2  // This file is part of the Spectrum library.
     3  //
     4  // The Spectrum 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 Spectrum 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 Spectrum library. If not, see <http://www.gnu.org/licenses/>.
    16  
    17  package core
    18  
    19  import (
    20  	"github.com/SmartMeshFoundation/Spectrum/log"
    21  	"math/big"
    22  
    23  	"github.com/SmartMeshFoundation/Spectrum/common"
    24  	"github.com/SmartMeshFoundation/Spectrum/consensus"
    25  	"github.com/SmartMeshFoundation/Spectrum/core/types"
    26  	"github.com/SmartMeshFoundation/Spectrum/core/vm"
    27  )
    28  
    29  // ChainContext supports retrieving headers and consensus parameters from the
    30  // current blockchain to be used during transaction processing.
    31  type ChainContext interface {
    32  	// Engine retrieves the chain's consensus engine.
    33  	Engine() consensus.Engine
    34  
    35  	// GetHeader returns the hash corresponding to their hash.
    36  	GetHeader(common.Hash, uint64) *types.Header
    37  }
    38  
    39  // NewEVMContext creates a new context for use in the EVM.
    40  func NewEVMContext(msg Message, header *types.Header, chain ChainContext, author *common.Address) vm.Context {
    41  	// If we don't have an explicit author (i.e. not mining), extract from the header
    42  	var beneficiary common.Address
    43  	beneficiary, _ = chain.Engine().Author(header) // Ignore error, we're past header validation
    44  	/*
    45  		if author == nil {
    46  			beneficiary, _ = chain.Engine().Author(header) // Ignore error, we're past header validation
    47  		} else {
    48  			beneficiary = *author
    49  		}
    50  	*/
    51  	log.Debug("<<NewEVMContext.SetCoinbase>>", "num", header.Number, "ignore_author", author, "beneficiary", beneficiary)
    52  	return vm.Context{
    53  		CanTransfer: CanTransfer,
    54  		Transfer:    Transfer,
    55  		GetHash:     GetHashFn(header, chain),
    56  		Origin:      msg.From(),
    57  		Coinbase:    beneficiary,
    58  		BlockNumber: new(big.Int).Set(header.Number),
    59  		Time:        new(big.Int).Set(header.Time),
    60  		Difficulty:  new(big.Int).Set(header.Difficulty),
    61  		GasLimit:    new(big.Int).Set(header.GasLimit),
    62  		GasPrice:    new(big.Int).Set(msg.GasPrice()),
    63  	}
    64  }
    65  
    66  // GetHashFn returns a GetHashFunc which retrieves header hashes by number
    67  func GetHashFn(ref *types.Header, chain ChainContext) func(n uint64) common.Hash {
    68  	return func(n uint64) common.Hash {
    69  		for header := chain.GetHeader(ref.ParentHash, ref.Number.Uint64()-1); header != nil; header = chain.GetHeader(header.ParentHash, header.Number.Uint64()-1) {
    70  			if header.Number.Uint64() == n {
    71  				return header.Hash()
    72  			}
    73  		}
    74  
    75  		return common.Hash{}
    76  	}
    77  }
    78  
    79  // CanTransfer checks wether there are enough funds in the address' account to make a transfer.
    80  // This does not take the necessary gas in to account to make the transfer valid.
    81  func CanTransfer(db vm.StateDB, addr common.Address, amount *big.Int) bool {
    82  	b := db.GetBalance(addr)
    83  	log.Debug("<<evm.CanTransfer>>", "addr", addr.Hex(), "amount", amount, "balance", b, "cantransfer", b.Cmp(amount) >= 0)
    84  	return b.Cmp(amount) >= 0
    85  }
    86  
    87  // Transfer subtracts amount from sender and adds amount to recipient using the given Db
    88  func Transfer(db vm.StateDB, sender, recipient common.Address, amount *big.Int) {
    89  	db.SubBalance(sender, amount)
    90  	db.AddBalance(recipient, amount)
    91  }