CreateFile Sector/Block level equivalent

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Scott Bell - 30 Aug 2006 23:36 GMT

Hello all,

What is the equivalent in the .NET Framework for accessing
a device at the block/sector level such as one would when
using CreateFile on a device like "\\.\D:"? Attempting to create
a BinaryReader on a FileStream opened (read-only) on "D:"
yields an Access Denied exception.

Thanks,

- Scott

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Carl Daniel [VC++ MVP] - 31 Aug 2006 00:50 GMT

> Hello all,
>
[quoted text clipped - 3 lines]
> a BinaryReader on a FileStream opened (read-only) on "D:"
> yields an Access Denied exception.

Use P/Invoke to call CreateFile and ReadFile directly passing in the
appropriate options to open a device.

http://www.pinvoke.net/default.aspx/kernel32/CreateFile.html
http://www.pinvoke.net/default.aspx/kernel32/ReadFile.html

-cd

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Willy Denoyette [MVP] - 31 Aug 2006 09:36 GMT

| > Hello all,
| >
[quoted text clipped - 11 lines]
|
| -cd

Note that there is no need to Pinvoke Win32's ReadFile, the handle (use a
SafeHandle in V2) returned by CreateFile can be used to create a FileStream,
this class has a number of contructor overloads that take an IntPtr
(representing the handle) or a SafeHandle.

Willy.

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Scott Bell - 31 Aug 2006 21:41 GMT

Willy,

Thanks, the following worked out to be the most ideal:

[DllImport("Kernel32.dll", SetLastError = true, CharSet =
CharSet.Auto)]
static extern SafeFileHandle CreateFile(
string fileName,
[MarshalAs(UnmanagedType.U4)] FileAccess fileAccess,
[MarshalAs(UnmanagedType.U4)] FileShare fileShare,
int securityAttributes,
[MarshalAs(UnmanagedType.U4)] FileMode creationDisposition,
int flags,
IntPtr template);

- Scott

> Note that there is no need to Pinvoke Win32's ReadFile, the handle (use a
> SafeHandle in V2) returned by CreateFile can be used to create a FileStream,
> this class has a number of contructor overloads that take an IntPtr
> (representing the handle) or a SafeHandle.
>
> Willy.

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CreateFile Sector/Block level equivalent

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