github.com/cheng762/platon-go@v1.8.17-0.20190529111256-7deff2d7be26/core/vm/contract.go (about)

     1  // Copyright 2015 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 vm
    18  
    19  import (
    20  	"math/big"
    21  
    22  	"github.com/PlatONnetwork/PlatON-Go/common"
    23  )
    24  
    25  // ContractRef is a reference to the contract's backing object
    26  type ContractRef interface {
    27  	Address() common.Address
    28  }
    29  
    30  // AccountRef implements ContractRef.
    31  //
    32  // Account references are used during EVM initialisation and
    33  // it's primary use is to fetch addresses. Removing this object
    34  // proves difficult because of the cached jump destinations which
    35  // are fetched from the parent contract (i.e. the caller), which
    36  // is a ContractRef.
    37  type AccountRef common.Address
    38  
    39  // Address casts AccountRef to a Address
    40  func (ar AccountRef) Address() common.Address { return (common.Address)(ar) }
    41  
    42  // Contract represents an ethereum contract in the state database. It contains
    43  // the contract code, calling arguments. Contract implements ContractRef
    44  type Contract struct {
    45  	// CallerAddress is the result of the caller which initialised this
    46  	// contract. However when the "call method" is delegated this value
    47  	// needs to be initialised to that of the caller's caller.
    48  	CallerAddress common.Address
    49  	caller        ContractRef
    50  	self          ContractRef
    51  
    52  	jumpdests destinations // result of JUMPDEST analysis.
    53  
    54  	Code     []byte
    55  	CodeHash common.Hash
    56  	CodeAddr *common.Address
    57  	Input    []byte
    58  
    59  	ABI     []byte
    60  	ABIHash common.Hash
    61  	ABIAddr *common.Address
    62  
    63  	Gas   uint64
    64  	value *big.Int
    65  
    66  	Args []byte
    67  
    68  	DelegateCall bool
    69  }
    70  
    71  // NewContract returns a new contract environment for the execution of EVM.
    72  func NewContract(caller ContractRef, object ContractRef, value *big.Int, gas uint64) *Contract {
    73  	c := &Contract{CallerAddress: caller.Address(), caller: caller, self: object, Args: nil}
    74  
    75  	if parent, ok := caller.(*Contract); ok {
    76  		// Reuse JUMPDEST analysis from parent context if available.
    77  		c.jumpdests = parent.jumpdests
    78  	} else {
    79  		c.jumpdests = make(destinations)
    80  	}
    81  
    82  	// Gas should be a pointer so it can safely be reduced through the run
    83  	// This pointer will be off the state transition
    84  	c.Gas = gas
    85  	// ensures a value is set
    86  	c.value = value
    87  
    88  	return c
    89  }
    90  
    91  // AsDelegate sets the contract to be a delegate call and returns the current
    92  // contract (for chaining calls)
    93  func (c *Contract) AsDelegate() *Contract {
    94  	c.DelegateCall = true
    95  	// NOTE: caller must, at all times be a contract. It should never happen
    96  	// that caller is something other than a Contract.
    97  	parent := c.caller.(*Contract)
    98  	c.CallerAddress = parent.CallerAddress
    99  	c.value = parent.value
   100  
   101  	return c
   102  }
   103  
   104  // GetOp returns the n'th element in the contract's byte array
   105  func (c *Contract) GetOp(n uint64) OpCode {
   106  	return OpCode(c.GetByte(n))
   107  }
   108  
   109  // GetByte returns the n'th byte in the contract's byte array
   110  func (c *Contract) GetByte(n uint64) byte {
   111  	if n < uint64(len(c.Code)) {
   112  		return c.Code[n]
   113  	}
   114  
   115  	return 0
   116  }
   117  
   118  // Caller returns the caller of the contract.
   119  //
   120  // Caller will recursively call caller when the contract is a delegate
   121  // call, including that of caller's caller.
   122  func (c *Contract) Caller() common.Address {
   123  	return c.CallerAddress
   124  }
   125  
   126  // UseGas attempts the use gas and subtracts it and returns true on success
   127  func (c *Contract) UseGas(gas uint64) (ok bool) {
   128  	if c.Gas < gas {
   129  		return false
   130  	}
   131  	c.Gas -= gas
   132  	return true
   133  }
   134  
   135  // Address returns the contracts address
   136  func (c *Contract) Address() common.Address {
   137  	return c.self.Address()
   138  }
   139  
   140  // Value returns the contracts value (sent to it from it's caller)
   141  func (c *Contract) Value() *big.Int {
   142  	return c.value
   143  }
   144  
   145  // SetCode sets the code to the contract
   146  func (c *Contract) SetCode(hash common.Hash, code []byte) {
   147  	c.Code = code
   148  	c.CodeHash = hash
   149  }
   150  
   151  // SetCallCode sets the code of the contract and address of the backing data
   152  // object
   153  func (c *Contract) SetCallCode(addr *common.Address, hash common.Hash, code []byte) {
   154  	c.Code = code
   155  	c.CodeHash = hash
   156  	c.CodeAddr = addr
   157  }
   158  
   159  // todo:
   160  func (c *Contract) SetCallAbi(addr *common.Address, hash common.Hash, abi []byte) {
   161  	c.ABI = abi
   162  	c.ABIHash = hash
   163  	c.ABIAddr = addr
   164  }