Multi tool use

Memory Mapped Region initial data

I want to create memory-mapped region using CreateFileMapping without any specific disk-file bound, but bound (using MapViewOfFileEx) to a specific memory address. Protection of such region needs to be read-only from beginning. Then, I cannot write data to such a region. If this region would be created for specific disk-file, initial data would come from file content. How I can fill this read-only region with initial data?

CreateFileMapping

MapViewOfFileEx

Example:
Most Windows processes have memory regions which are mapped (and not bound to any file path) and read-only since creation, they contain data. How was this achieved? How were these regions filled with data?

1 Answer
1

exist only one way do this - first map section with PAGE_READWRITE, init it content, possible unmap, and then map it again - with PAGE_READONLY protection. for example

PAGE_READWRITE

PAGE_READONLY

ULONG demo_map(PVOID BaseAddress, ULONG size, ULONG (*Init)(PVOID pv, ULONG size))
{
ULONG dwError = NOERROR;
if (HANDLE hSection = CreateFileMappingW(INVALID_HANDLE_VALUE, 0, PAGE_READWRITE, 0, size, 0))
{
if (PVOID pv = MapViewOfFile(hSection, FILE_MAP_READ|FILE_MAP_WRITE, 0, 0, 0))
{
dwError = Init(pv, size);
UnmapViewOfFile(pv);
}
else
{
dwError = GetLastError();
}

if (!dwError)
{
dwError = MapViewOfFileEx(hSection, FILE_MAP_READ, 0, 0, 0, BaseAddress) ? NOERROR : GetLastError();
}

CloseHandle(hSection);
}

return dwError;
}


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