Translation of CreateFile dll in dot net

[news.microsoft.com]

Hello,

i'm having problems to call a api dll in vb dot net.
I absolutely want to use this api call and none of the frame calls.

This is my declaration:
*****************
Public Structure SECURITY_ATTRIBUTES
Public nLength As UInt32
Public lpSecurityDescriptor As IntPtr
Public bInheritHandle As Int32
End Structure

' Desired Access
Public Const FILE_READ_DATA = 1
Public Const FILE_WRITE_DATA = 2
Public Const FILE_APPEND_DATA = 4

' ShareMode
Public Const FILE_SHARE_READ = &H1
Public Const FILE_SHARE_WRITE = &H2

' CreationDisposition
Public Const CREATE_NEW = 1
Public Const OPEN_EXISTING = 3

Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" _
(ByVal lpFileName As String, _
ByVal dwDesiredAccess As Long, _
ByVal dwShareMode As Long, _
ByVal lpSecurityAttributes As SECURITY_ATTRIBUTES, _
ByVal dwCreationDisposition As Long, _
ByVal dwFlagsAndAttributes As Long, _
ByVal hTemplateFile As IntPtr) _
As Long


This is the call:
***********

Dim lFile As Long = LibWrap.CreateFile("c:\test\myfile.dat",
LibWrap.FILE_READ_DATA, LibWrap.FILE_SHARE_READ, Nothing,
LibWrap.OPEN_EXISTING, 0, Nothing)


Anyone an idea?
This is my first api call.

Grtz.

 

[Al Reid]

You need to be aware of data type mapping between .Net and the API calls and also be aware that if you are using declarations from
VB5/6 that a VB5/6 Long maps to a VB.Net Integer.

Without looking in any detail, first try changing all Long to Integer in the CreateFile declaration.

 

[news.microsoft.com]

I've changed the code with no luck:

Declaration:
*********
Const FILE_READ_DATA = 1
Const OPEN_EXISTING = 3
Const FILE_SHARE_READ = &H1
Const FILE_SHARE_WRITE = &H2
Const FILE_ATTRIBUTE_NORMAL = &H80

<StructLayout(LayoutKind.Sequential)> _
Structure SECURITY_ATTRIBUTES
Public nLength As Int32
Public lpSecurityDescriptor As IntPtr
Public bInheritHandle As Boolean
End Structure

Declare Auto Function CreateFile Lib "kernel32" ( _
ByVal lpFileName As String, _
ByVal dwDesiredAccess As Int32, _
ByVal dwShareMode As Int32, _
ByRef lpSecurityAttributes As IntPtr, _
ByVal dwCreationDistribution As Int32, _
ByVal dwFlagsAndAttributes As Int32, _
ByVal hTemplateFile As IntPtr _
) As IntPtr

Call:
****
Dim fh As IntPtr

fh = CreateFile("c:\test\test.txt", FILE_READ_DATA, FILE_SHARE_READ,
IntPtr.Zero, OPEN_EXISTING, 0, IntPtr.Zero)

If fh.ToInt32 = -1 Then
MessageBox.Show("Invalid")
End If


I don't see what's wrong ...

You need to be aware of data type mapping between .Net and the API calls

and also be aware that if you are using declarations from

 

[Al Reid]

That's because you changed the Longs to Int32, which was no change at all. You need to use either Integer or Int16. A DWORD is two
(2) 8 bit words or a 16-bit integer.

 

[news.microsoft.com]

I tried it but that doesn't work either.
thanks.

That's because you changed the Longs to Int32, which was no change at all.

You need to use either Integer or Int16. A DWORD is two

 

[Herfried K. Wagner [MVP]]

i'm having problems to call a api dll in vb dot net.
I absolutely want to use this api call and none of the frame calls.

Any reason for using 'CreateFile' instead of .NET's 'System.IO.FileStream'
class or similar classes?

 

[Claes Bergefall]

See inline

That's because you changed the Longs to Int32, which was no change at all.
You need to use either Integer or Int16. A DWORD is two
(2) 8 bit words or a 16-bit integer.

Ehh, no. A DWORD is 32 bits, same as Long in VB6 and Int32/Integer in VB.NET


Try this:

Const FILE_READ_DATA As Int32 = 1
Const OPEN_EXISTING As Int32 = 3
Const FILE_SHARE_READ As Int32 = &H1
Const FILE_SHARE_WRITE As Int32 = &H2
Const FILE_ATTRIBUTE_NORMAL As Int32 = &H80

<StructLayout(LayoutKind.Sequential)> _
Structure SECURITY_ATTRIBUTES
Public nLength As Int32
Public lpSecurityDescriptor As IntPtr
Public bInheritHandle As Boolean
End Structure

Declare Auto Function CreateFile Lib "kernel32" ( _
<MarshalAs(UnmanagedType.LPTStr)> ByVal lpFileName As String, _
ByVal dwDesiredAccess As Int32, _
ByVal dwShareMode As Int32, _
ByRef lpSecurityAttributes As SECURITY_ATTRIBUTES, _
ByVal dwCreationDistribution As Int32, _
ByVal dwFlagsAndAttributes As Int32, _
ByVal hTemplateFile As IntPtr _
) As IntPtr

If this doesn't work try changing the lpSecurityAttributes parameter to
ByVal instead of ByRef

/claes

 

[Al Reid]

Sorry, ehh, you're right. My bad. Anyhow, when converting VB5/6 Declarations, the VB5/6 Long converts to a VB.Net Integer.

Also the SECURITY_ATTRIBUTES structure needs to be adjusted as well.

 

[news.microsoft.com]

That did it.
Thank you all.

See inline



Ehh, no. A DWORD is 32 bits, same as Long in VB6 and Int32/Integer in VB.NET

Try this:

Const FILE_READ_DATA As Int32 = 1
Const OPEN_EXISTING As Int32 = 3
Const FILE_SHARE_READ As Int32 = &H1
Const FILE_SHARE_WRITE As Int32 = &H2
Const FILE_ATTRIBUTE_NORMAL As Int32 = &H80

<StructLayout(LayoutKind.Sequential)> _
Structure SECURITY_ATTRIBUTES
Public nLength As Int32
Public lpSecurityDescriptor As IntPtr
Public bInheritHandle As Boolean
End Structure

Declare Auto Function CreateFile Lib "kernel32" ( _
<MarshalAs(UnmanagedType.LPTStr)> ByVal lpFileName As String, _
ByVal dwDesiredAccess As Int32, _
ByVal dwShareMode As Int32, _
ByRef lpSecurityAttributes As SECURITY_ATTRIBUTES, _
ByVal dwCreationDistribution As Int32, _
ByVal dwFlagsAndAttributes As Int32, _
ByVal hTemplateFile As IntPtr _
) As IntPtr

If this doesn't work try changing the lpSecurityAttributes parameter to
ByVal instead of ByRef

/claes