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Imports System.Runtime.InteropServices.ComTypes
Imports System.IO
Imports System.Runtime.InteropServices
<System.Serializable()> Public NotInheritable Class ComIStreamWrapper
Implements IStream
Private Const STG_E_INVALIDFUNCTION As Integer = &H80030001
Public ReadOnly baseStream As Stream
Private position As Long = -1
Sub New(ByVal stream As Stream)
baseStream = stream
End Sub
Private Sub SetSizeToPosition()
If position <> -1 Then
If position > baseStream.Length Then
baseStream.SetLength(position)
End If
baseStream.Position = position
position = -1
End If
End Sub
Public Sub Read(ByVal pv As Byte(), ByVal cb As Integer, ByVal pcbRead As IntPtr) Implements IStream.Read
Dim read__1 As Integer = 0
If cb <> 0 Then
SetSizeToPosition()
read__1 = baseStream.Read(pv, 0, cb)
End If
If pcbRead <> IntPtr.Zero Then
Marshal.WriteInt32(pcbRead, read__1)
End If
End Sub
Public Sub Write(ByVal pv As Byte(), ByVal cb As Integer, ByVal pcbWritten As IntPtr) Implements IStream.Write
If cb <> 0 Then
SetSizeToPosition()
baseStream.Write(pv, 0, cb)
End If
If pcbWritten <> IntPtr.Zero Then
Marshal.WriteInt32(pcbWritten, cb)
End If
End Sub
Public Sub Seek(ByVal dlibMove As Long, ByVal dwOrigin As Integer, ByVal plibNewPosition As IntPtr) Implements IStream.Seek
Dim length As Long = baseStream.Length
Dim newPosition As Long
Select Case CType(dwOrigin, SeekOrigin)
Case SeekOrigin.Begin
newPosition = dlibMove
Exit Select
Case SeekOrigin.Current
If position = -1 Then
newPosition = baseStream.Position + dlibMove
Else
newPosition = position + dlibMove
End If
Exit Select
Case SeekOrigin.[End]
newPosition = length + dlibMove
Exit Select
Case Else
Throw New ExternalException(Nothing, STG_E_INVALIDFUNCTION)
End Select
If newPosition > length Then
position = newPosition
Else
baseStream.Position = newPosition
position = -1
End If
If plibNewPosition <> IntPtr.Zero Then
Marshal.WriteInt64(plibNewPosition, newPosition)
End If
End Sub
Public Sub SetSize(ByVal libNewSize As Long) Implements IStream.SetSize
baseStream.SetLength(libNewSize)
End Sub
Public Sub CopyTo(ByVal pstm As IStream, ByVal cb As Long, ByVal pcbRead As IntPtr, ByVal pcbWritten As IntPtr) Implements IStream.CopyTo
Dim buffer As Byte()
Dim written As Long = 0
Dim read As Integer
Dim count As Integer
If cb <> 0 Then
If cb < 4096 Then
count = Convert.ToInt32(cb)
Else
count = 4096
End If
buffer = New Byte(count - 1) {}
SetSizeToPosition()
While True
If (InlineAssignHelper(read, baseStream.Read(buffer, 0, count))) = 0 Then
Exit While
End If
pstm.Write(buffer, read, IntPtr.Zero)
written += read
If written >= cb Then
Exit While
End If
If cb - written < 4096 Then
count = Convert.ToInt32(cb - written)
End If
End While
End If
If pcbRead <> IntPtr.Zero Then
Marshal.WriteInt64(pcbRead, written)
End If
If pcbWritten <> IntPtr.Zero Then
Marshal.WriteInt64(pcbWritten, written)
End If
End Sub
Public Sub Commit(ByVal grfCommitFlags As Integer) Implements IStream.Commit
baseStream.Flush()
SetSizeToPosition()
End Sub
Public Sub Revert() Implements IStream.Revert
Throw New Runtime.InteropServices.ExternalException(Nothing, STG_E_INVALIDFUNCTION)
End Sub
Public Sub LockRegion(ByVal libOffset As Long, ByVal cb As Long, ByVal dwLockType As Integer) Implements IStream.LockRegion
Throw New Runtime.InteropServices.ExternalException(Nothing, STG_E_INVALIDFUNCTION)
End Sub
Public Sub UnlockRegion(ByVal libOffset As Long, ByVal cb As Long, ByVal dwLockType As Integer) Implements IStream.UnlockRegion
Throw New Runtime.InteropServices.ExternalException(Nothing, STG_E_INVALIDFUNCTION)
End Sub
Public Sub Stat(ByRef pstatstg As System.Runtime.InteropServices.ComTypes.STATSTG, ByVal grfStatFlag As Integer) Implements IStream.Stat
pstatstg = New System.Runtime.InteropServices.ComTypes.STATSTG()
pstatstg.cbSize = baseStream.Length
End Sub
Public Sub Clone(ByRef ppstm As IStream) Implements IStream.Clone
ppstm = Nothing
Throw New Runtime.InteropServices.ExternalException(Nothing, STG_E_INVALIDFUNCTION)
End Sub
Private Shared Function InlineAssignHelper(Of T)(ByRef target As T, ByVal value As T) As T
target = value
Return value
End Function
End Class
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