C# P/Invoke 损坏的内存

Question

我在使用 C# P/Invoke 时遇到一个奇怪的问题，当从 C# 编组到 C++ 时，结构已损坏，除非通过 ref 传递结构，但不会发生在同一调用和其他调用中的所有其他结构.

第一次调用 100% 没有问题，即使使用数组也是如此。第二次调用仅在我将 Struct8 作为 ref 传递时才起作用，如果我不这样做，那么当它命中 C++ 代码时内存已损坏，这没有意义，因为为什么所有其他结构都可以工作而不必通过引用传递？

我的结构是 1:1（要用 MarshalAs 等字符的字符串） C++ 代码大部分使用 C 风格的数组

我正在拨打以下电话

var struct1 = new Struct1() { Name = @"TEST" };
Create(
    struct1,
    ref struct2,
    new Struct3() { Channel = string.IsNullOrEmpty(request.Channel) ? "TESTCHANNEL" : request.Channel },
    Array.Empty<Struct4>(),
    new Struct5() { Something = 0 },
    out var struct6,
    out var struct7,
    out var struct2Detail
);

var struct8 = new Struct8() { Number = struct2.Number, TrySomething = 1 };
Initialize(struct1, struct8, out struct6, out struct2Detail);

只有当我这样称呼它时才有效:

Initialize(struct1, ref struct8, out struct6, out struct2Detail);

C# 编组 + 结构的伪代码

public static void Create(
    Struct1 struct1
    ,ref Struct2 struct2
    ,Struct3 struct3
    ,Struct4[] struct4
    ,Struct5 struct5
    ,out Struct6 struct6
    ,out Struct7 struct7
    ,out Struct2Detail struct2Detail
)
{
    int numProcFields = struct4.Length;
    Net5_Create(
        struct1
        ,ref struct2
        ,struct3
        ,ref numProcFields
        ,struct4
        ,struct5
        ,out struct6
        ,out struct7
        ,out struct2Detail
    );
}

[DllImport(LIBNAME, CallingConvention = CallingConvention.Cdecl)]
public static extern void Net5_Create(
    Struct1 struct1
    ,[In, Out] ref Struct2 struct2
    ,Struct3 struct3
    ,[In, Out] ref int numProcFields
    ,Struct4[] struct4
    ,Struct5 struct5
    ,out Struct6 struct6
    ,out Struct7 struct7
    ,out Struct2Detail struct2Detail
);

public static void Initialize(
    Struct1 struct1
    ,Struct8 struct8
    ,out Struct6 struct6
    ,out Struct2Detail struct2Detail
)
{
    Net5_Initialize(
        struct1
        ,struct8
        ,out struct6
        ,out struct2Detail
    );
}

[DllImport(LIBNAME, CallingConvention = CallingConvention.Cdecl)]
public static extern void Net5_Initialize(
    Struct1 struct1
    ,Struct8 struct8
    ,out Struct6 struct6
    ,out Struct2Detail struct2Detail
);

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct Struct1
{
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 33)]
    public string Name;
}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct Struct2
{
    public int Number;
    public int Reference;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 65)]
    public string ReferenceValue;
    public int ReferenceYear;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 16)]
    public string DateCreated;
}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct Struct4
{
    public int ObjectType;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 65)]
    public string Name;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 201)]
    public string Value;
}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct Struct6
{
    public int Number1;
    public int Number2;
    public int Number3;
    public int Number4;
    public int Number5;
    public int Number6;
    public int Number7;
    public int Number8;
}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct Struct7
{
    public int Number1;
    public int Number2;
    public int Number3;
    public int Number4;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 65)]
    public string String1;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 257)]
    public string String2;
}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct Struct8
{
    public int Number;
    public int TrySomething;
}

C++ 端的代码

#ifdef __cplusplus
extern "C" {
#endif
#ifdef _WIN32
#    define MODULE_API __declspec(dllexport)
#else
#  define MODULE_API
#endif

MODULE_API void Net5_Initialize(
    Struct1* struct1
    ,Struct8* struct8
    ,Struct6* struct6
    ,Struct2Detail* struct2Detail
);

void Net5_Initialize(
        Struct1* struct1
        ,Struct8* struct8
        ,Struct6* struct6
        ,Struct2Detail* struct2Detail
    )
{
    dotnetInstance->Initialize(
         struct1
        , struct8
        , struct6
        , struct2Detail
    );
}
#ifdef __cplusplus
}
#endif
#endif

// typedef __int32 int32;
struct Struct1
{
    char Name[33];
    Struct1()
    {
        Name[0] = 0;
    }
    void Function1() { ... }
}

struct Struct2
{
    int32 Number;
    int32 Reference;
    char ReferenceValue[65];
    int32 ReferenceYear;
    char DateCreated[16];
    Struct2()
    {
        Number = 0;
        Reference = 0;
        ReferenceValue[0] = 0;
        ReferenceYear = 0;
        DateCreated[0] = 0;
    }
    void Function1() { ... }
}

struct Struct4
{
    int32 ObjectType;
    char Name[65];
    char Value[201];
    Struct4()
    {
        ObjectType = 0;
        Name[0] = 0;
        Value[0] = 0;
    }
    void Function1() { ... }
}

struct Struct6
{
    int32 Number1;
    int32 Number2;
    int32 Number3;
    int32 Number4;
    int32 Number5;
    int32 Number6;
    int32 Number7;
    int32 Number8;
    Struct6()
    {
        Number1 = 0;
        Number2 = 0;
        Number3 = 0;
        Number4 = 0;
        Number5 = 0;
        Number6 = 0;
        Number7 = 0;
        Number8 = 0;
    }
    void Function1() { ... }
}

struct Struct7
{
    int32 Number1;
    int32 Number2;
    int32 Number3;
    int32 Number4;
    char String1[65]
    char String2[257];
    Struct7()
    {
        Number1 = 0;
        Number2 = 0;
        Number3 = 0;
        Number4 = 0;
        String1[0] = 0;
        String2[0] = 0;
    }
    void Function1() { ... }
}
struct Struct8
{
  int32 Number;
  int32 TrySomething;
  Struct8()
  {
    Number = 0;
    TrySomething = 0;
  }
    void Function1() { ... }
}
void Class::Create(Struct1* struct1, Struct2* struct2, Struct3* struct3, int32* numProcFields, Struct4* struct4, Struct5* struct5, Struct6* struct6, Struct7* struct7, Struct2Detail* struct2Detail)
{
    ...
}
void Class::Initialize(Struct1* struct1, Struct8* struct8, Struct6* struct6, Struct2Detail* struct2Detail)
{
    lprintf("Initialize - Started (%d)", struct8->Number);
    ...
}

Answer 1

事实证明问题不在于 Initialize，如果 Create 的输入数组内存也是 byref

工作创建

[DllImport(LIBNAME, CallingConvention = CallingConvention.Cdecl)]
public static extern void Net5_Create(
    ref Struct1 struct1
    ,ref Struct2 struct2
    ,ref Struct3 struct3
    ,ref int numProcFields
    ,[MarshalAs(UnmanagedType.LPArray)] Struct4[] struct4
    ,ref Struct5 struct5
    ,ref Struct6 struct6
    ,ref Struct7 struct7
    ,ref Struct2Detail struct2Detail
);

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