From: Albert Almeida [albert@fce.uclv.edu.cu]
Sent: Friday, January 11, 2002 2:01 PM
To: NT Developers Interest List
Cc: jeyaram_g@ctd.hcltech.com
Subject: [ntdev] Re: How to create a memory mapped file in a NT driver

Hello from Cuba!

You first have to create a section object using the undocumented function
NtCreateSection whose prototype is:

NTSTATUS
NtCreateSection(
 OUT PHANDLE SectionHandle,
 IN ACCESS_MASK DesiredAccess,
 IN POBJECT_ATTRIBUTES ObjectAttributes OPTIONAL,
 IN PLARGE_INTEGER MaximumSize OPTIONAL,
 IN ULONG SectionPageProtection,
 IN ULONG AllocationAttributes,
 IN HANDLE FileHandle OPTIONAL
 );

The bit masks for SectionPageProtecction, AllocationAttributes and
DesiredAccess are defined in the NT4 DDK.
Later you have to map a section view in memory by using the function
NtMapViewOfSection which is defined as follows:

NTSTATUS
NtMapViewOfSection(
    IN HANDLE SectionHandle,
    IN HANDLE ProcessHandle,
    IN OUT PVOID *BaseAddress,
    IN ULONG ZeroBits,
    IN ULONG CommitSize,
    IN OUT PLARGE_INTEGER SectionOffset OPTIONAL,
    IN OUT PULONG ViewSize,
    IN SECTION_INHERIT InheritDisposition,
    IN ULONG AllocationType,
    IN ULONG Protect
    );

To unmap the view you use NtUnmapViewOfSection:

NTSTATUS
NtUnmapViewOfSection(
    IN HANDLE ProcessHandle,
    IN PVOID BaseAddress
    );

Well, thatīs it! I hope this helps!

Best regards,

Albert Almeida



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