1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
// Copyright 2016 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package core
import (
"math/big"
"github.com/dexon-foundation/dexon/common"
"github.com/dexon-foundation/dexon/consensus"
"github.com/dexon-foundation/dexon/core/state"
"github.com/dexon-foundation/dexon/core/types"
"github.com/dexon-foundation/dexon/core/vm"
)
// ChainContext supports retrieving headers and consensus parameters from the
// current blockchain to be used during transaction processing.
type ChainContext interface {
// Engine retrieves the chain's consensus engine.
Engine() consensus.Engine
// GetHeader returns the hash corresponding to their hash.
GetHeader(common.Hash, uint64) *types.Header
// StateAt returns the statedb given a root hash.
StateAt(common.Hash) (*state.StateDB, error)
// GetHeaderByNumber returns the header given a block number.
GetHeaderByNumber(number uint64) *types.Header
// GetRoundHeight returns the mapping between round and height.
GetRoundHeight(uint64) (uint64, bool)
}
// NewVMContext creates a new context for use in the EVM.
func NewVMContext(msg Message, header *types.Header, chain ChainContext, author *common.Address) *vm.Context {
// If we don't have an explicit author (i.e. not mining), extract from the header
var beneficiary common.Address
if author == nil {
beneficiary, _ = chain.Engine().Author(header) // Ignore error, we're past header validation
} else {
beneficiary = *author
}
return &vm.Context{
CanTransfer: CanTransfer,
Transfer: Transfer,
GetHash: GetHashFn(header, chain),
StateAtNumber: StateAtNumberFn(chain),
GetRoundHeight: GetRoundHeightFn(chain),
Origin: msg.From(),
Coinbase: beneficiary,
BlockNumber: new(big.Int).Set(header.Number),
Time: new(big.Int).SetUint64(header.Time),
Randomness: header.Randomness,
Difficulty: new(big.Int).Set(header.Difficulty),
Round: new(big.Int).SetUint64(header.Round),
GasLimit: header.GasLimit,
GasPrice: new(big.Int).Set(msg.GasPrice()),
IntPool: vm.NewIntPool(),
}
}
// StateAtNumberFn returns a StateAtNumberFunc which allows the retrieval of
// statedb at a given block height.
func StateAtNumberFn(chain ChainContext) func(n uint64) (*state.StateDB, error) {
return func(n uint64) (*state.StateDB, error) {
header := chain.GetHeaderByNumber(n)
return chain.StateAt(header.Root)
}
}
func GetRoundHeightFn(chain ChainContext) func(uint64) (uint64, bool) {
if chain != nil {
return chain.GetRoundHeight
}
return func(uint64) (uint64, bool) {
return 0, false
}
}
// GetHashFn returns a GetHashFunc which retrieves header hashes by number
func GetHashFn(ref *types.Header, chain ChainContext) func(n uint64) common.Hash {
var cache map[uint64]common.Hash
return func(n uint64) common.Hash {
// If there's no hash cache yet, make one
if cache == nil {
cache = map[uint64]common.Hash{
ref.Number.Uint64() - 1: ref.ParentHash,
}
}
// Try to fulfill the request from the cache
if hash, ok := cache[n]; ok {
return hash
}
// Not cached, iterate the blocks and cache the hashes
for header := chain.GetHeader(ref.ParentHash, ref.Number.Uint64()-1); header != nil; header = chain.GetHeader(header.ParentHash, header.Number.Uint64()-1) {
cache[header.Number.Uint64()-1] = header.ParentHash
if n == header.Number.Uint64()-1 {
return header.ParentHash
}
}
return common.Hash{}
}
}
// CanTransfer checks whether there are enough funds in the address' account to make a transfer.
// This does not take the necessary gas in to account to make the transfer valid.
func CanTransfer(db vm.StateDB, addr common.Address, amount *big.Int) bool {
return db.GetBalance(addr).Cmp(amount) >= 0
}
// Transfer subtracts amount from sender and adds amount to recipient using the given Db
func Transfer(db vm.StateDB, sender, recipient common.Address, amount *big.Int) {
db.SubBalance(sender, amount)
db.AddBalance(recipient, amount)
}
|