I have this code to get all handle of some process by PID using NtQuerySystemInformation()

#ifndef UNICODE
#define UNICODE
#endif

#include <windows.h>
#include <stdio.h>
#include <cassert>

#define NT_SUCCESS(x) ((x) >= 0)
#define STATUS_INFO_LENGTH_MISMATCH 0xc0000004

#define SystemHandleInformation 16
#define ObjectBasicInformation 0
#define ObjectNameInformation 1
#define ObjectTypeInformation 2

typedef NTSTATUS(NTAPI* _NtQuerySystemInformation)(
    ULONG SystemInformationClass,
    PVOID SystemInformation,
    ULONG SystemInformationLength,
    PULONG ReturnLength
    );

typedef NTSTATUS(NTAPI* _NtDuplicateObject)(
    HANDLE SourceProcessHandle,
    HANDLE SourceHandle,
    HANDLE TargetProcessHandle,
    PHANDLE TargetHandle,
    ACCESS_MASK DesiredAccess,
    ULONG Attributes,
    ULONG Options
    );
typedef NTSTATUS(NTAPI* _NtQueryObject)(
    HANDLE ObjectHandle,
    ULONG ObjectInformationClass,
    PVOID ObjectInformation,
    ULONG ObjectInformationLength,
    PULONG ReturnLength
    );

typedef struct _UNICODE_STRING
{
    USHORT Length;
    USHORT MaximumLength;
    PWSTR Buffer;
} UNICODE_STRING, * PUNICODE_STRING;

typedef struct _SYSTEM_HANDLE
{
    ULONG ProcessId;
    BYTE ObjectTypeNumber;
    BYTE Flags;
    USHORT Handle;
    PVOID Object;
    ACCESS_MASK GrantedAccess;
} SYSTEM_HANDLE, * PSYSTEM_HANDLE;

typedef struct _SYSTEM_HANDLE_INFORMATION
{
    ULONG HandleCount;
    SYSTEM_HANDLE Handles[1];
} SYSTEM_HANDLE_INFORMATION, * PSYSTEM_HANDLE_INFORMATION;

typedef enum _POOL_TYPE
{
    NonPagedPool,
    PagedPool,
    NonPagedPoolMustSucceed,
    DontUseThisType,
    NonPagedPoolCacheAligned,
    PagedPoolCacheAligned,
    NonPagedPoolCacheAlignedMustS
} POOL_TYPE, * PPOOL_TYPE;

typedef struct _OBJECT_TYPE_INFORMATION
{
    UNICODE_STRING Name;
    ULONG TotalNumberOfObjects;
    ULONG TotalNumberOfHandles;
    ULONG TotalPagedPoolUsage;
    ULONG TotalNonPagedPoolUsage;
    ULONG TotalNamePoolUsage;
    ULONG TotalHandleTableUsage;
    ULONG HighWaterNumberOfObjects;
    ULONG HighWaterNumberOfHandles;
    ULONG HighWaterPagedPoolUsage;
    ULONG HighWaterNonPagedPoolUsage;
    ULONG HighWaterNamePoolUsage;
    ULONG HighWaterHandleTableUsage;
    ULONG InvalidAttributes;
    GENERIC_MAPPING GenericMapping;
    ULONG ValidAccess;
    BOOLEAN SecurityRequired;
    BOOLEAN MaintainHandleCount;
    USHORT MaintainTypeList;
    POOL_TYPE PoolType;
    ULONG PagedPoolUsage;
    ULONG NonPagedPoolUsage;
} OBJECT_TYPE_INFORMATION, * POBJECT_TYPE_INFORMATION;

PVOID GetLibraryProcAddress(LPCSTR LibraryName, LPCSTR ProcName)
{
    return GetProcAddress(GetModuleHandleA(LibraryName), ProcName);
}



int wmain(int argc, WCHAR* argv[])
{
    _NtQuerySystemInformation NtQuerySystemInformation{};
    {
        auto const p_proc{ GetLibraryProcAddress("ntdll.dll", "NtQuerySystemInformation") };
        assert(p_proc); // TODO handle error...
        static_assert(sizeof(_NtQuerySystemInformation) == sizeof(p_proc), "pointer size mismatch");
        memcpy(&NtQuerySystemInformation, &p_proc, sizeof(NtQuerySystemInformation)); // deep copy
    }
    _NtDuplicateObject NtDuplicateObject{};
    {
        auto const p_proc{ GetLibraryProcAddress("ntdll.dll", "NtDuplicateObject") };
        assert(p_proc); // TODO handle error...
        static_assert(sizeof(_NtDuplicateObject) == sizeof(p_proc), "pointer size mismatch");
        memcpy(&NtDuplicateObject, &p_proc, sizeof(NtDuplicateObject)); // deep copy
    }
    _NtQueryObject NtQueryObject{};
    {
        auto const p_proc{ GetLibraryProcAddress("ntdll.dll", "NtQueryObject") };
        assert(p_proc); // TODO handle error...
        static_assert(sizeof(_NtQueryObject) == sizeof(p_proc), "pointer size mismatch");
        memcpy(&NtQueryObject, &p_proc, sizeof(NtQueryObject)); // deep copy
    }

    NTSTATUS status;
    PSYSTEM_HANDLE_INFORMATION handleInfo;
    ULONG handleInfoSize = 0x10000;
    ULONG pid;
    HANDLE processHandle;
    ULONG i;

    if (argc < 2)
    {
        printf("Usage: handles [pid]n");
        return 1;
    }

    pid = _wtoi(argv[1]);

    if (!(processHandle = OpenProcess(PROCESS_DUP_HANDLE, FALSE, pid)))
    {
        printf("Could not open PID %d! (Don't try to open a system process.)n", pid);
        return 1;
    }

    handleInfo = (PSYSTEM_HANDLE_INFORMATION)malloc(handleInfoSize);

    /* NtQuerySystemInformation won't give us the correct buffer size,
       so we guess by doubling the buffer size. */
    while ((status = NtQuerySystemInformation(
        SystemHandleInformation,
        handleInfo,
        handleInfoSize,
        NULL
    )) == STATUS_INFO_LENGTH_MISMATCH)
        handleInfo = (PSYSTEM_HANDLE_INFORMATION)realloc(handleInfo, handleInfoSize *= 2);

    /* NtQuerySystemInformation stopped giving us STATUS_INFO_LENGTH_MISMATCH. */
    if (!NT_SUCCESS(status))
    {
        printf("NtQuerySystemInformation failed!n");
        return 1;
    }

    for (i = 0; i < handleInfo->HandleCount; i++)
    {
        SYSTEM_HANDLE handle = handleInfo->Handles[i];
        HANDLE dupHandle = NULL;
        POBJECT_TYPE_INFORMATION objectTypeInfo;
        PVOID objectNameInfo;
        UNICODE_STRING objectName;
        ULONG returnLength;

        /* Check if this handle belongs to the PID the user specified. */
        if (handle.ProcessId != pid) {
           // printf("Error - handle of other process %lu!n", handle.ProcessId);
            continue;
        }

        /* Duplicate the handle so we can query it. */
        if (!NT_SUCCESS(NtDuplicateObject(processHandle, (HANDLE)handle.Handle,GetCurrentProcess(), &dupHandle, 0, 0, 0)))
        {
            //printf("[%#x] Error!n", handle.Handle);
            continue;
        }

        /* Query the object type. */
        objectTypeInfo = (POBJECT_TYPE_INFORMATION)malloc(0x1000);
        if (!NT_SUCCESS(NtQueryObject(
            dupHandle,
            ObjectTypeInformation,
            objectTypeInfo,
            0x1000,
            NULL
        )))
        {
            printf("[%#x] Error!n", handle.Handle);
            CloseHandle(dupHandle);
            continue;
        }

        /* Query the object name (unless it has an access of
           0x0012019f, on which NtQueryObject could hang. */
        if (handle.GrantedAccess == 0x0012019f)
        {
            /* We have the type, so display that. */
            printf(
                "[%#x] %.*S: (did not get name)n",
                handle.Handle,
                objectTypeInfo->Name.Length / 2,
                objectTypeInfo->Name.Buffer
            );
            free(objectTypeInfo);
            CloseHandle(dupHandle);
            continue;
        }

        objectNameInfo = malloc(0x1000);
        if (!NT_SUCCESS(NtQueryObject(
            dupHandle,
            ObjectNameInformation,
            objectNameInfo,
            0x1000,
            &returnLength
        )))
        {
            /* Reallocate the buffer and try again. */
            objectNameInfo = realloc(objectNameInfo, returnLength);
            if (!NT_SUCCESS(NtQueryObject(
                dupHandle,
                ObjectNameInformation,
                objectNameInfo,
                returnLength,
                NULL
            )))
            {
                /* We have the type name, so just display that. */
                printf(
                    "[%#x] %.*S: (could not get name)n",
                    handle.Handle,
                    objectTypeInfo->Name.Length / 2,
                    objectTypeInfo->Name.Buffer
                );
                free(objectTypeInfo);
                free(objectNameInfo);
                CloseHandle(dupHandle);
                continue;
            }
        }

        /* Cast our buffer into an UNICODE_STRING. */
        objectName = *(PUNICODE_STRING)objectNameInfo;

        /* Print the information! */
        if (objectName.Length)
        {
            /* The object has a name. */
            printf(
                "[%#x] %.*S: %.*Sn",
                handle.Handle,
                objectTypeInfo->Name.Length / 2,
                objectTypeInfo->Name.Buffer,
                objectName.Length / 2,
                objectName.Buffer
            );
        }
        else
        {
            /* Print something else. */
            printf(
                "[%#x] %.*S: (unnamed)n",
                handle.Handle,
                objectTypeInfo->Name.Length / 2,
                objectTypeInfo->Name.Buffer
            );
        }

        free(objectTypeInfo);
        free(objectNameInfo);
        CloseHandle(dupHandle);
    }

    free(handleInfo);
    CloseHandle(processHandle);

    return 0;
}

Now I want to understand when another process accesses the handle of my process, but I don’t understand how this can be done.
A similar problem was solved here using C# (see comment and chat under question) – How to get notified when a new handle to my process is opened with OpenProcess from a foreign process? . As far as I understand, I need ‘found all currently opened handles to your process’
after this you need filter processes in 0 session. may be exporter too. another processes – probably cheat or debuggers’