Number of mapped views to a shared memory on Windows

问题

Is there a way to check how many views have been mapped on to a memory mapped file on Windows?

Something like the equivalent of shmctl(... ,IPC_STAT,...) on Linux?

回答1:

I had the same need to access the number of shared views. So I created this question: Accessing the number of shared memory mapped file views (Windows)

You may find a solution that suits your needs there.

---

As per Scath comment, I am going to add here the proposed solution, although merit should go to eryksun and RbMm. Making use of NtQueryObject call one can access the HandleCount (although it may not be 100% reliable):

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

typedef NTSTATUS (__stdcall *NtQueryObjectFuncPointer) (
            HANDLE                   Handle,
            OBJECT_INFORMATION_CLASS ObjectInformationClass,
            PVOID                    ObjectInformation,
            ULONG                    ObjectInformationLength,
            PULONG                   ReturnLength);

int main(void)
{
    _PUBLIC_OBJECT_BASIC_INFORMATION pobi;
    ULONG rLen;

    // Create the memory mapped file (in system pagefile) (better in global namespace
    // but needs SeCreateGlobalPrivilege privilege)
    HANDLE hMap = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE|SEC_COMMIT,
                  0, 1, "Local\\UniqueShareName");

    // Get the NtQUeryObject function pointer and then the handle basic information
    NtQueryObjectFuncPointer _NtQueryObject = (NtQueryObjectFuncPointer)GetProcAddress(
            GetModuleHandle("ntdll.dll"), "NtQueryObject");

    _NtQueryObject(hMap, ObjectBasicInformation, (PVOID)&pobi, (ULONG)sizeof(pobi), &rLen);

    // Check limit
    if (pobi.HandleCount > 4) {
        printf("Limit exceeded: %ld > 4\n", pobi.HandleCount);
        exit(1);
    }
    //...
    Sleep(30000);
}

来源：https://stackoverflow.com/questions/41593517/number-of-mapped-views-to-a-shared-memory-on-windows