github.com/theQRL/go-zond@v0.1.1/core/evm.go (about)

     1  // Copyright 2016 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 core
    18  
    19  import (
    20  	"math/big"
    21  
    22  	"github.com/theQRL/go-zond/common"
    23  	"github.com/theQRL/go-zond/consensus"
    24  	"github.com/theQRL/go-zond/core/types"
    25  	"github.com/theQRL/go-zond/core/vm"
    26  )
    27  
    28  // ChainContext supports retrieving headers and consensus parameters from the
    29  // current blockchain to be used during transaction processing.
    30  type ChainContext interface {
    31  	// Engine retrieves the chain's consensus engine.
    32  	Engine() consensus.Engine
    33  
    34  	// GetHeader returns the header corresponding to the hash/number argument pair.
    35  	GetHeader(common.Hash, uint64) *types.Header
    36  }
    37  
    38  // NewEVMBlockContext creates a new context for use in the EVM.
    39  func NewEVMBlockContext(header *types.Header, chain ChainContext, author *common.Address) vm.BlockContext {
    40  	var (
    41  		beneficiary common.Address
    42  		baseFee     *big.Int
    43  		random      *common.Hash
    44  	)
    45  
    46  	// If we don't have an explicit author (i.e. not mining), extract from the header
    47  	if author == nil {
    48  		beneficiary, _ = chain.Engine().Author(header) // Ignore error, we're past header validation
    49  	} else {
    50  		beneficiary = *author
    51  	}
    52  	if header.BaseFee != nil {
    53  		baseFee = new(big.Int).Set(header.BaseFee)
    54  	}
    55  	if header.Difficulty.Cmp(common.Big0) == 0 {
    56  		random = &header.MixDigest
    57  	}
    58  	return vm.BlockContext{
    59  		CanTransfer:   CanTransfer,
    60  		Transfer:      Transfer,
    61  		GetHash:       GetHashFn(header, chain),
    62  		Coinbase:      beneficiary,
    63  		BlockNumber:   new(big.Int).Set(header.Number),
    64  		Time:          header.Time,
    65  		Difficulty:    new(big.Int).Set(header.Difficulty),
    66  		BaseFee:       baseFee,
    67  		GasLimit:      header.GasLimit,
    68  		Random:        random,
    69  		ExcessBlobGas: header.ExcessBlobGas,
    70  	}
    71  }
    72  
    73  // NewEVMTxContext creates a new transaction context for a single transaction.
    74  func NewEVMTxContext(msg *Message) vm.TxContext {
    75  	return vm.TxContext{
    76  		Origin:     msg.From,
    77  		GasPrice:   new(big.Int).Set(msg.GasPrice),
    78  		BlobHashes: msg.BlobHashes,
    79  	}
    80  }
    81  
    82  // GetHashFn returns a GetHashFunc which retrieves header hashes by number
    83  func GetHashFn(ref *types.Header, chain ChainContext) func(n uint64) common.Hash {
    84  	// Cache will initially contain [refHash.parent],
    85  	// Then fill up with [refHash.p, refHash.pp, refHash.ppp, ...]
    86  	var cache []common.Hash
    87  
    88  	return func(n uint64) common.Hash {
    89  		if ref.Number.Uint64() <= n {
    90  			// This situation can happen if we're doing tracing and using
    91  			// block overrides.
    92  			return common.Hash{}
    93  		}
    94  		// If there's no hash cache yet, make one
    95  		if len(cache) == 0 {
    96  			cache = append(cache, ref.ParentHash)
    97  		}
    98  		if idx := ref.Number.Uint64() - n - 1; idx < uint64(len(cache)) {
    99  			return cache[idx]
   100  		}
   101  		// No luck in the cache, but we can start iterating from the last element we already know
   102  		lastKnownHash := cache[len(cache)-1]
   103  		lastKnownNumber := ref.Number.Uint64() - uint64(len(cache))
   104  
   105  		for {
   106  			header := chain.GetHeader(lastKnownHash, lastKnownNumber)
   107  			if header == nil {
   108  				break
   109  			}
   110  			cache = append(cache, header.ParentHash)
   111  			lastKnownHash = header.ParentHash
   112  			lastKnownNumber = header.Number.Uint64() - 1
   113  			if n == lastKnownNumber {
   114  				return lastKnownHash
   115  			}
   116  		}
   117  		return common.Hash{}
   118  	}
   119  }
   120  
   121  // CanTransfer checks whether there are enough funds in the address' account to make a transfer.
   122  // This does not take the necessary gas in to account to make the transfer valid.
   123  func CanTransfer(db vm.StateDB, addr common.Address, amount *big.Int) bool {
   124  	return db.GetBalance(addr).Cmp(amount) >= 0
   125  }
   126  
   127  // Transfer subtracts amount from sender and adds amount to recipient using the given Db
   128  func Transfer(db vm.StateDB, sender, recipient common.Address, amount *big.Int) {
   129  	db.SubBalance(sender, amount)
   130  	db.AddBalance(recipient, amount)
   131  }