我花了一些时间思考这个问题，我需要你的帮助。 我的问题看起来有点类似于Stack Overflow上的许多问题，我浏览了很多，但仍未找到答案。
我需要编组结构字段，它是指向结构数组的指针。
问题是我需要这个结构从用C编写的遗留外部库接收。
通过使用Marshal.AllocHGlobal和Marshal.StructureToPtr锁定大小正确的内存，我发现了很多关于传递结构作为指针的提示。
我还找到了如何接收作为指针返回的结构的指南：您可以使用[MarshalAs]修饰符。
不幸的是，这无济于事，因为大多数[MarshalAs]修饰符似乎不适用于结构字段。
在下面的示例中，我能够通过两个步骤接收所需的数据：
MiddleStruct数据及其中的指针PtrToStructure 问题是我想确保垃圾收集器不会修改接收指针引用的内存。我有什么方法可以使用一步读取InnerStructure中的数据吗？
typedef struct OuterStruct {
MiddleStruct mStruct;
} OuterStruct;
typedef struct MiddleStruct {
int count;
InnerStruct FAR *innerData;
} MiddleStruct;
typedef struct InnerStruct {
int number;
char data[64];
} InnerStruct;
[StructLayout(LayoutKind.Sequential, Pack = 4)]
public class OuterStruct
{
public MiddleStruct mStruct;
};
[StructLayout(LayoutKind.Sequential, Pack = 4)]
public struct MiddleStruct
{
public int count;
public IntPtr pIStruct; //pointer to array of InnerStruct
}
[StructLayout(LayoutKind.Sequential, Pack = 4)]
public struct InnerStruct
{
int number;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 64)]
public bytes[] data;
};
[DllImport("legacy.dll", CharSet = CharSet.Ansi)]
public static extern short getData([In, Out, MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(myCustomMarshaler))] OuterStruct sStruct);
OuterStruct oStruct;
getData(out oStruct);
int count = oStruct.mStruct.count;
IntPtr pIStruct = oStruct.mStruct.pIStruct;
InnerStruct[] iStructArray = new InnerStruct[count];
int infoSize = Marshal.SizeOf(new iStructArray());
for (int i = 0; i < count; i++)
{
IntPtr targetPtr = new IntPtr(pIStruct.ToInt32() + infoSize * i);
iStructArray[i] = (InnerStruct)Marshal.PtrToStructure(targetPtr, typeof(InnerStruct));
}
WriteLine(iStructArray);
更新
我已经创建了自定义编组程序，但我想不出返回值的方法。 知道该数组是引用类型，有没有办法将intPtr转换为数组？ 我尝试使用object而不是intPtr并相应地转换它，但是没有用。
public class myCustomMarshaler : ICustomMarshaler
{
[ThreadStatic]
private OuterStruct marshaledObj;
private static myCustomMarshaler marshaler = null;
public static ICustomMarshaler GetInstance(string cookie)
{
if (marshaler == null)
{
marshaler = new myCustomMarshaler();
}
return marshaler;
}
#region ICustomMarshaler Members
public int GetNativeDataSize()
{
return Marshal.SizeOf(typeof(OuterStruct));
}
public object MarshalNativeToManaged(System.IntPtr pNativeData)
{
Marshal.PtrToStructure(pNativeData, this.marshaledObj);
int count = this.marshaledObj.mStruct.count;
IntPtr pIStruct = this.marshaledObj.mStruct.pIStruct;
InnerStruct[] iStructArray = new InnerStruct[count];
int dataSize = Marshal.SizeOf(new InnerStruct());
for (int i = 0; i < count; i++)
{
iStructArray[i] = (InnerStruct)Marshal.PtrToStructure(new IntPtr(pIStruct.ToInt32() + dataSize * i), typeof(InnerStruct));
}
//*** how do I include iStructArray in return?
return this.marshaledObj;
}
public System.IntPtr MarshalManagedToNative(object managedObj)
{
if (!(managedObj is OuterStruct))
{
throw new ArgumentException("Specified object is not a OuterStruct object.", "managedObj");
}
else
{
this.marshaledObj = (OuterStruct)managedObj;
}
IntPtr ptr = Marshal.AllocHGlobal(this.GetNativeDataSize());
if (ptr == IntPtr.Zero)
{
throw new Exception("Unable to allocate memory to.");
}
Marshal.StructureToPtr(this.marshaledObj, ptr, false);
return ptr;
}
public void CleanUpManagedData(object managedObj)
{
}
public void CleanUpNativeData(System.IntPtr pNativeData)
{
Marshal.FreeHGlobal(pNativeData);
}
#endregion
}
答案 0 :(得分：1)
我通过使用另一个类将其包装在oStruct周围并添加字典字段来返回其他数据来解决我的问题。虽然它对我有用，但它使用起来非常不方便，并且不能很好地扩展。 无论如何，这可能对某人有用：
public class WrapperClass
{
public OuterStruct oStruct;
public Dictionary<string, object> auxData;
public WrapperClass()
{
this.oStruct = new OuterStruct();
this.auxData = new Dictionary<string, object>();
}
}
public class myCustomMarshaler : ICustomMarshaler
{
[ThreadStatic]
private WrapperClass marshaledObj;
private static myCustomMarshaler marshaler = null;
public static ICustomMarshaler GetInstance(string cookie)
{
if (marshaler == null)
{
marshaler = new myCustomMarshaler();
}
return marshaler;
}
public int GetNativeDataSize()
{
return Marshal.SizeOf(typeof(OuterStruct));
}
public object MarshalNativeToManaged(System.IntPtr pNativeData)
{
Marshal.PtrToStructure(pNativeData, this.marshaledObj);
int count = this.marshaledObj.mStruct.count;
IntPtr pIStruct = this.marshaledObj.mStruct.pIStruct;
InnerStruct[] iStructArray = new InnerStruct[count];
int dataSize = Marshal.SizeOf(new InnerStruct());
for (int i = 0; i < count; i++)
{
iStructArray[i] = (InnerStruct)Marshal.PtrToStructure(new IntPtr(pIStruct.ToInt32() + dataSize * i), typeof(InnerStruct));
}
// Add additional data to wrapper
this.marshaledObj.auxData.Add("iStructArray", iStructArray);
return this.marshaledObj;
}
public System.IntPtr MarshalManagedToNative(object managedObj)
{
if (!(managedObj is WrapperClass))
{
throw new ArgumentException("Specified object is not a WrapperClass object.", "managedObj");
}
else
{
this.marshaledObj = (WrapperClass)managedObj;
}
IntPtr ptr = Marshal.AllocHGlobal(this.GetNativeDataSize());
if (ptr == IntPtr.Zero)
{
throw new Exception("Unable to allocate memory to.");
}
Marshal.StructureToPtr(this.marshaledObj.oStruct, ptr, false);
return ptr;
}
public void CleanUpManagedData(object managedObj)
{
}
public void CleanUpNativeData(System.IntPtr pNativeData)
{
Marshal.FreeHGlobal(pNativeData);
}
}
[DllImport("legacy.dll", CharSet = CharSet.Ansi)]
public static extern short getData([In, Out, MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(myCustomMarshaler))] OuterStruct wrapper);