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Editorial Team
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Asked: 2026-05-12T18:16:48+00:00

In Windows it’s possible to open devices and volumes via CreateFile() . I’ve used

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In Windows it’s possible to open devices and volumes via CreateFile(). I’ve used this successfully before to ReadFile() from devices, but now I want to switch to memory-mapping. In the following code, I receive INVALID_HANDLE_VALUE for the value of b, and c is set to 87, ERROR_INVALID_PARAMETER.

HANDLE a = ::CreateFileA("\\\\.\\h:", GENERIC_READ, FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_READONLY | FILE_FLAG_NO_BUFFERING, NULL);
HANDLE b = ::CreateFileMappingA(a, NULL, PAGE_READONLY, 0, 0, NULL);
DWORD c = ::GetLastError();

How can I get this to work?

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1 Answer

  1. Editorial Team

    You can’t. CreateFileMapping can only create a mapping to a file. Take a look at the difference in the documentation between the hFile parameter for ReadFile and for CreateFileMapping. For ReadFile it lists all the different types of handles it accepts (which includes devices), for CreateFileMapping it only lists files.

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