diff options
| -rw-r--r-- | core/vm/environment.go | 4 | ||||
| -rw-r--r-- | core/vm/vm.go | 48 |
2 files changed, 34 insertions, 18 deletions
diff --git a/core/vm/environment.go b/core/vm/environment.go index 25bd2515e..e61676409 100644 --- a/core/vm/environment.go +++ b/core/vm/environment.go @@ -8,6 +8,8 @@ import ( "github.com/ethereum/go-ethereum/core/state" ) +// Environment is is required by the virtual machine to get information from +// it's own isolated environment. For an example see `core.VMEnv` type Environment interface { State() *state.StateDB @@ -33,6 +35,8 @@ type Environment interface { Create(me ContextRef, data []byte, gas, price, value *big.Int) ([]byte, error, ContextRef) } +// StructLog is emited to the Environment each cycle and lists information about the curent internal state +// prior to the execution of the statement. type StructLog struct { Pc uint64 Op OpCode diff --git a/core/vm/vm.go b/core/vm/vm.go index e4f6e9268..bf8bbcdc2 100644 --- a/core/vm/vm.go +++ b/core/vm/vm.go @@ -10,6 +10,7 @@ import ( "github.com/ethereum/go-ethereum/params" ) +// Vm implements VirtualMachine type Vm struct { env Environment @@ -27,11 +28,13 @@ type Vm struct { After func(*Context, error) } +// New returns a new Virtual Machine func New(env Environment) *Vm { return &Vm{env: env, debug: Debug, Recoverable: true} } -func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) { +// Run loops and evaluates the contract's code with the given input data +func (self *Vm) Run(context *Context, input []byte) (ret []byte, err error) { self.env.SetDepth(self.env.Depth() + 1) defer self.env.SetDepth(self.env.Depth() - 1) @@ -59,7 +62,7 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) { if context.CodeAddr != nil { if p := Precompiled[context.CodeAddr.Str()]; p != nil { - return self.RunPrecompiled(p, callData, context) + return self.RunPrecompiled(p, input, context) } } @@ -69,13 +72,15 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) { } var ( - op OpCode - codehash = crypto.Sha3Hash(code) - mem = NewMemory() - stack = newStack() - pc = uint64(0) - statedb = self.env.State() - + op OpCode // current opcode + codehash = crypto.Sha3Hash(code) // codehash is used when doing jump dest caching + mem = NewMemory() // bound memory + stack = newStack() // local stack + pc = uint64(0) // program counter + statedb = self.env.State() // current state + + // jump evaluates and checks whether the given jump destination is a valid one + // if valid move the `pc` otherwise return an error. jump = func(from uint64, to *big.Int) error { if !context.jumpdests.has(codehash, code, to) { nop := context.GetOp(to.Uint64()) @@ -97,20 +102,22 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) { self.log(pc, op, context.Gas, mem, stack, context) + // calculate the new memory size and gas price for the current executing opcode newMemSize, gas, err := self.calculateGasAndSize(context, caller, op, statedb, mem, stack) if err != nil { return nil, err } + // Use the calculated gas. When insufficient gas is present, use all gas and return an + // Out Of Gas error if !context.UseGas(gas) { - tmp := new(big.Int).Set(context.Gas) context.UseGas(context.Gas) return context.Return(nil), OOG(gas, tmp) } - + // Resize the memory calculated previously mem.Resize(newMemSize.Uint64()) switch op { @@ -364,11 +371,11 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) { stack.push(value) case CALLDATALOAD: - data := getData(callData, stack.pop(), common.Big32) + data := getData(input, stack.pop(), common.Big32) stack.push(common.Bytes2Big(data)) case CALLDATASIZE: - l := int64(len(callData)) + l := int64(len(input)) stack.push(big.NewInt(l)) case CALLDATACOPY: @@ -377,7 +384,7 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) { cOff = stack.pop() l = stack.pop() ) - data := getData(callData, cOff, l) + data := getData(input, cOff, l) mem.Set(mOff.Uint64(), l.Uint64(), data) @@ -623,6 +630,8 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) { } } +// calculateGasAndSize calculates the required given the opcode and stack items calculates the new memorysize for +// the operation. This does not reduce gas or resizes the memory. func (self *Vm) calculateGasAndSize(context *Context, caller ContextRef, op OpCode, statedb *state.StateDB, mem *Memory, stack *Stack) (*big.Int, *big.Int, error) { var ( gas = new(big.Int) @@ -764,20 +773,22 @@ func (self *Vm) calculateGasAndSize(context *Context, caller ContextRef, op OpCo return newMemSize, gas, nil } -func (self *Vm) RunPrecompiled(p *PrecompiledAccount, callData []byte, context *Context) (ret []byte, err error) { - gas := p.Gas(len(callData)) +// RunPrecompile runs and evaluate the output of a precompiled contract defined in contracts.go +func (self *Vm) RunPrecompiled(p *PrecompiledAccount, input []byte, context *Context) (ret []byte, err error) { + gas := p.Gas(len(input)) if context.UseGas(gas) { - ret = p.Call(callData) + ret = p.Call(input) return context.Return(ret), nil } else { - tmp := new(big.Int).Set(context.Gas) return nil, OOG(gas, tmp) } } +// log emits a log event to the environment for each opcode encountered. This is not to be confused with the +// LOG* opcode. func (self *Vm) log(pc uint64, op OpCode, gas *big.Int, memory *Memory, stack *Stack, context *Context) { if Debug { mem := make([]byte, len(memory.Data())) @@ -795,6 +806,7 @@ func (self *Vm) log(pc uint64, op OpCode, gas *big.Int, memory *Memory, stack *S } } +// Environment returns the current workable state of the VM func (self *Vm) Env() Environment { return self.env } |