当尝试从多个DBase IV文件中的memofields读取c ++结构到C＃（。Net 4）然后将它们插入到MSSQL 2008中时，我遇到了一个问题。数据正在从DBase文件中提取出来但我似乎在管理不安全的调用时出错了，因为我随机收到以下错误：
FatalExecutionEngineError was detected
Message: The runtime has encountered a fatal error. The address of the error was
at 0x791fa62c, on thread 0x16c0. The error code is 0xc0000005. This error may be
a bug in the CLR or in the unsafe or non-verifiable portions of user code. Common
sources of this bug include user marshaling errors for COM-interop or PInvoke,
which may corrupt the stack.
以下是我用来读取数据的代码。此代码成功完成，我从文件中获取的数据是正确的。调用此函数后几分钟发生错误，当使用nhibernate将对象插入数据库时（我把它排除在外，因为我认为这对问题无关紧要）。
[StructLayout(LayoutKind.Sequential, Pack = 1)]
public struct Event
{
public int Number;
public int Month;
public int Day;
public int Year;
public int Hour;
public int Minute;
public int Second;
public UInt32 UPCTime;
public int BlobSize;
[MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = DataLengths.MAX_EVENT_TITLE_LENGTH)]
public string Title;
[MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = DataLengths.MAX_TRIGGER_LENGTH)]
public string Trigger;
}
public struct Trigger
{
[MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 1)]
public string Control;
public int Index;
[MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 1)]
public string Mode;
[MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 1)]
public string RecordFreq;
public int Pre;
public int Post;
[MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 1)]
public string Source;
public int Delay;
public int EventUserNotify;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 7)]
public int[] Spare;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = DataLengths.MAX_EVENT_SENSORS)]
public int[] Sensors;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
public struct Value
{
public Trigger Trigger;
public string[] SensorLabels;
public Point[] Point;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
public struct Point
{
public Single Value;
[MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 1)]
public string State;
}
//The dbf is from the java xBasej library that I compiled into a dll using IKVM.net
public Dictionary<Event, Value> Read(DBF dbf)
{
Dictionary<Event, Value> eventData = new Dictionary<Event, Value>();
try
{
for (int i = 1; i <= dbf.getRecordCount(); i++)
{
dbf.gotoRecord(i);
MemoField memofield = (MemoField)dbf.getField("MemoField");
// Perform the conversion from one encoding to the other.
byte[] blob = memofield.getBytes();
if (blob.Length == 0)
{
continue;
}
MemoryStream memoryStream = null;
BinaryReader binaryReader = null;
GCHandle eventHandle = new GCHandle();
GCHandle triggerHandle = new GCHandle();
GCHandle sensorLabelHandle = new GCHandle();
GCHandle pointHandle = new GCHandle();
try
{
memoryStream = new MemoryStream(blob);
binaryReader = new BinaryReader(memoryStream);
//The data was orignally C++ structures so we read the bytes back into C# equivalent
//structures.
int eventDataSize = Marshal.SizeOf(typeof(Event));
eventHandle = GCHandle.Alloc(binaryReader.ReadBytes(eventDataSize), GCHandleType.Pinned);
Event @event = (Event)Marshal.PtrToStructure(eventHandle.AddrOfPinnedObject(), typeof(Event));
//Read the event trigger data
int triggerDataSize = Marshal.SizeOf(typeof(Trigger));
triggerHandle = GCHandle.Alloc(binaryReader.ReadBytes(triggerDataSize), GCHandleType.Pinned);
Trigger trigger = (Trigger)Marshal.PtrToStructure(triggerHandle.AddrOfPinnedObject(), typeof(Trigger));
Value value = new Value();
value.Trigger = trigger;
triggerHandle.Free();
//Read all the sensor labels
List<string> sensorLableList = new List<string>();
for (int sensorIndex = 0; sensorIndex < DataLengths.MAX_EVENT_SENSORS; sensorIndex++)
{
int sensorLableDataSize = DataLengths.MAX_LABEL_LENGTH;
sensorLabelHandle = GCHandle.Alloc(binaryReader.ReadBytes(sensorLableDataSize), GCHandleType.Pinned);
string label = Marshal.PtrToStringAnsi(sensorLabelHandle.AddrOfPinnedObject(), sensorLableDataSize).Trim();
sensorLableList.Add(label);
sensorLabelHandle.Free();
}
value.SensorLabels = sensorLableList.ToArray();
//Read all the recorded sensor data
List<Point> pointList = new List<Point>();
for (int pointIndex = 0; pointIndex < DataLengths.MAX_EVENT_SENSORS; pointIndex++)
{
int pointDataSize = Marshal.SizeOf(typeof(Point));
pointHandle = GCHandle.Alloc(binaryReader.ReadBytes(pointDataSize), GCHandleType.Pinned);
Point point = (Point)Marshal.PtrToStructure(pointHandle.AddrOfPinnedObject(), typeof(Point));
pointList.Add(point);
pointHandle.Free();
}
value.Point = pointList.ToArray();
eventData.Add(@event, value);
eventHandle.Free();
}
finally
{
//Free all the resources used to get the data
if (memoryStream != null) { memoryStream.Close(); }
if (binaryReader != null) { binaryReader.Close(); }
if (eventHandle.IsAllocated) { eventHandle.Free(); }
if (triggerHandle.IsAllocated) { triggerHandle.Free(); }
if (sensorLabelHandle.IsAllocated) { sensorLabelHandle.Free(); }
if (pointHandle.IsAllocated) { pointHandle.Free(); }
GC.Collect();
}
}
}
finally
{
if (dbf != null)
{
dbf.close();
}
}
return eventData;
}
答案 0 :(得分：4)
有趣的失败模式，这不应该发生。您通常会获得FEEE，因为垃圾收集堆已被破坏。这通常很容易解释为行为不当的pinvoked本机函数，它执行溢出缓冲区之类的操作。不过这里没有pinvoke。
然而，对于这次事故，有一个很好的候选人：[MarshalAsAttribute(UnmanagedType.ByValTStr, SizeConst = 1)]
public string Control;
为此编组的目的是编组一个C字符串，一个以零结尾的字符数组。 SizeConst = 1无法通过设计正常工作，只留下零终止符的空间，而不是任何字符。最重要的是，.dbf文件不包含零终止字符串，根据字段声明它们是固定宽度。
访问冲突是否实际上是由编组人员犯错误引起的，这是一个悬而未决的问题，它可以像试图找到零终结器一样容易炸弹。找不到一个并且错误地进入未映射的内存页面。
Anyhoo，你做错了。您必须在结构声明中使用char []而不是字符串，并在[MarshalAs]属性中使用ByValArray。非常痛苦的编码btw。
答案 1 :(得分：0)
在Trigger结构中，您确定自己拥有合适的包装吗？看起来索引成员将在偏移量4处，因为您可能希望它在偏移1处？与前后相同。
此外，Control应该是什么尺寸？如果是字符串，通常非托管字符串以空值终止。通过指定长度1，这将指示我一个字符。如果是这种情况，为什么不使用char而不是字符串？
错误0xc0000005是访问冲突。
您是否尝试在调试器下运行并启用非托管代码调试？然后，您可以将访问冲突设置为在抛出时正确捕获，因为它可能在.NET框架代码中发生。然后，您可以查看内存并了解它可能正在做什么。