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Mode to disable backward jumps on NeoVM 3 #174

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Mode to disable backward jumps on NeoVM 3 #174

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1ba06ec
disable backward jumps
igormcoelho Jun 16, 2019
395e9b0
fail by time on unlimited mode
igormcoelho Jun 16, 2019
a4655d8
simplify
igormcoelho Jun 16, 2019
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20 changes: 10 additions & 10 deletions src/neo-vm/Debugger.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,17 +22,17 @@ public void AddBreakPoint(Script script, uint position)
hashset.Add(position);
}

public VMState Execute()
public VMState Execute(bool isLimited = false)
{
engine.State &= ~VMState.BREAK;
while (!engine.State.HasFlag(VMState.HALT) && !engine.State.HasFlag(VMState.FAULT) && !engine.State.HasFlag(VMState.BREAK))
ExecuteAndCheckBreakPoints();
ExecuteAndCheckBreakPoints(isLimited);
return engine.State;
}

private void ExecuteAndCheckBreakPoints()
private void ExecuteAndCheckBreakPoints(bool isLimited)
{
engine.ExecuteNext();
engine.ExecuteNext(isLimited);
if (engine.State == VMState.NONE && engine.InvocationStack.Count > 0 && break_points.Count > 0)
{
if (break_points.TryGetValue(engine.CurrentContext.Script, out HashSet<uint> hashset) && hashset.Contains((uint)engine.CurrentContext.InstructionPointer))
Expand All @@ -48,36 +48,36 @@ public bool RemoveBreakPoint(Script script, uint position)
return true;
}

public VMState StepInto()
public VMState StepInto(bool isLimited = false)
{
if (engine.State.HasFlag(VMState.HALT) || engine.State.HasFlag(VMState.FAULT))
return engine.State;
engine.ExecuteNext();
engine.ExecuteNext(isLimited);
if (engine.State == VMState.NONE)
engine.State = VMState.BREAK;
return engine.State;
}

public VMState StepOut()
public VMState StepOut(bool isLimited)
{
engine.State &= ~VMState.BREAK;
int c = engine.InvocationStack.Count;
while (!engine.State.HasFlag(VMState.HALT) && !engine.State.HasFlag(VMState.FAULT) && !engine.State.HasFlag(VMState.BREAK) && engine.InvocationStack.Count >= c)
ExecuteAndCheckBreakPoints();
ExecuteAndCheckBreakPoints(isLimited);
if (engine.State == VMState.NONE)
engine.State = VMState.BREAK;
return engine.State;
}

public VMState StepOver()
public VMState StepOver(bool isLimited = false)
{
if (engine.State.HasFlag(VMState.HALT) || engine.State.HasFlag(VMState.FAULT))
return engine.State;
engine.State &= ~VMState.BREAK;
int c = engine.InvocationStack.Count;
do
{
ExecuteAndCheckBreakPoints();
ExecuteAndCheckBreakPoints(isLimited);
}
while (!engine.State.HasFlag(VMState.HALT) && !engine.State.HasFlag(VMState.FAULT) && !engine.State.HasFlag(VMState.BREAK) && engine.InvocationStack.Count > c);
if (engine.State == VMState.NONE)
Expand Down
37 changes: 31 additions & 6 deletions src/neo-vm/ExecutionEngine.cs
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Expand Up @@ -175,15 +175,15 @@ public virtual void Dispose()
InvocationStack.Clear();
}

public VMState Execute()
public VMState Execute(bool isLimited = false)
{
State &= ~VMState.BREAK;
while (!State.HasFlag(VMState.HALT) && !State.HasFlag(VMState.FAULT))
ExecuteNext();
ExecuteNext(isLimited);
return State;
}

internal protected void ExecuteNext()
internal protected void ExecuteNext(bool isLimited = false)
{
if (InvocationStack.Count == 0)
{
Expand All @@ -194,7 +194,7 @@ internal protected void ExecuteNext()
try
{
Instruction instruction = CurrentContext.CurrentInstruction;
if (!PreExecuteInstruction() || !ExecuteInstruction() || !PostExecuteInstruction(instruction))
if (!PreExecuteInstruction(isLimited) || !ExecuteInstruction() || !PostExecuteInstruction(instruction))
State = VMState.FAULT;
}
catch
Expand Down Expand Up @@ -1088,9 +1088,34 @@ public ExecutionContext LoadScript(byte[] script, int rvcount = -1)
}

protected virtual bool OnSysCall(uint method) => false;

protected virtual bool PostExecuteInstruction(Instruction instruction) => true;

protected virtual bool PreExecuteInstruction() => true;
protected virtual bool PreExecuteInstruction(bool isLimited = false)
{
ExecutionContext context = CurrentContext;
Instruction instruction = context.CurrentInstruction;
switch(instruction.OpCode)
{
case OpCode.JMP:
case OpCode.JMPIF:
case OpCode.JMPIFNOT:
case OpCode.CALL:
{
if(isLimited)
{
// no backwards jump in limited mode
if(instruction.TokenI16 <= 0)
{
return false;
}
}
break;
}
default:
return true;
}
return true;
}
}
}
35 changes: 35 additions & 0 deletions tests/neo-vm.Tests/Tests/OpCodes/Jumps/JMP.json
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Original file line number Diff line number Diff line change
@@ -0,0 +1,35 @@
{
"category": "Jumps",
"name": "JMP",
"tests":
[
{
"name": "while(true)",
"script": "0x620000",
"isLimited": true,
"steps":
[
{
"actions":
[
"Execute"
],
"result":
{
"state": "FAULT",
"invocationStack":
[
{
"instructionPointer": 0,
"nextInstruction": "JMP",
"evaluationStack":
[
]
}
]
}
}
]
}
]
}
35 changes: 35 additions & 0 deletions tests/neo-vm.Tests/Tests/OpCodes/JumpsUnlimited/JMP.json
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Original file line number Diff line number Diff line change
@@ -0,0 +1,35 @@
{
"category": "JumpsUnlimited",
"name": "JMP",
"tests":
[
{
"name": "while(true) timeout 3000ms",
"script": "0x620000",
"isLimited": false,
"steps":
[
{
"actions":
[
"Execute"
],
"result":
{
"state": "FAULT",
"invocationStack":
[
{
"instructionPointer": 3,
"nextInstruction": "RET",
"evaluationStack":
[
]
}
]
}
}
]
}
]
}
3 changes: 3 additions & 0 deletions tests/neo-vm.Tests/Types/VMUTEntry.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,9 @@ public class VMUTEntry
[JsonProperty]
public string Name { get; set; }

[JsonProperty]
public bool IsLimited { get; set; }

[JsonProperty]
public VMUTStep[] Steps { get; set; }
}
Expand Down
20 changes: 20 additions & 0 deletions tests/neo-vm.Tests/UtVMJson.cs
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Expand Up @@ -3,6 +3,9 @@
using Microsoft.VisualStudio.TestTools.UnitTesting;
using Neo.Test.Extensions;
using Neo.Test.Types;
using System.Threading.Tasks;
using System;
using System.Diagnostics;

namespace Neo.Test
{
Expand All @@ -15,6 +18,23 @@ public class UtVMJson : VMJsonTestBase
[TestMethod]
public void TestOpCodesArrays() => TestJson("./Tests/OpCodes/Arrays");

[TestMethod]
public void TestOpCodesJumps() => TestJson("./Tests/OpCodes/Jumps");

[TestMethod]
[Timeout(3500)]
public void TestOpCodesJumpsUnlimited()
{
//Task.Factory.StartNew(() => TestJson("./Tests/OpCodes/JumpsUnlimited")).Wait(TimeSpan.FromSeconds(3));
var stopwatch = new Stopwatch();
stopwatch.Start();
var task1 = Task.Factory.StartNew(() => TestJson("./Tests/OpCodes/JumpsUnlimited"));
task1.Wait(TimeSpan.FromSeconds(3));
stopwatch.Stop();
// should fail on timer basis
Assert.IsTrue(stopwatch.ElapsedMilliseconds >= 3000);
}

[TestMethod]
public void TestOpCodesStack() => TestJson("./Tests/OpCodes/Stack");

Expand Down
9 changes: 5 additions & 4 deletions tests/neo-vm.Tests/VMJsonTestBase.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
using Neo.VM;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using System.Linq;

namespace Neo.Test
{
Expand Down Expand Up @@ -35,10 +36,10 @@ public void ExecuteTest(VMUT ut)
{
switch (run)
{
case VMUTActionType.Execute: debugger.Execute(); break;
case VMUTActionType.StepInto: debugger.StepInto(); break;
case VMUTActionType.StepOut: debugger.StepOut(); break;
case VMUTActionType.StepOver: debugger.StepOver(); break;
case VMUTActionType.Execute: debugger.Execute(test.IsLimited); break;
case VMUTActionType.StepInto: debugger.StepInto(test.IsLimited); break;
case VMUTActionType.StepOut: debugger.StepOut(test.IsLimited); break;
case VMUTActionType.StepOver: debugger.StepOver(test.IsLimited); break;
}
}

Expand Down