VB.NET

Get the Byte Count of the Last SFTP Read

Demonstrates the Chilkat SFtp.LastReadNumBytes method, which returns the number of bytes received by the most recent read for a handle. The only argument is the handle.

Background: SFTP reads may return fewer bytes than requested even before the end of the file, so knowing the actual count is useful for tracking progress and for advancing an explicit offset by the right amount. Both a normal EOF read and a failed read report 0, so pair this with Eof and LastReadFailed to interpret a zero-byte result correctly.

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Dim success As Boolean = False

'  Demonstrates the SFtp.LastReadNumBytes method, which returns the number of bytes received by
'  the most recent read for a handle.  The only argument is the handle.

Dim sftp As New Chilkat.SFtp

'  Connect, authenticate, and initialize the SFTP subsystem.
Dim port As Integer = 22
success = sftp.Connect("sftp.example.com",port)
If (success = False) Then
    Debug.WriteLine(sftp.LastErrorText)
    Exit Sub
End If


'  Normally you would not hard-code the password in source.  You should instead obtain it
'  from an interactive prompt, environment variable, or a secrets vault.
Dim password As String = "mySshPassword"

success = sftp.AuthenticatePw("mySshLogin",password)
If (success = False) Then
    Debug.WriteLine(sftp.LastErrorText)
    Exit Sub
End If


success = sftp.InitializeSftp()
If (success = False) Then
    Debug.WriteLine(sftp.LastErrorText)
    Exit Sub
End If


Dim handle As String = sftp.OpenFile("subdir/data.txt","readOnly","openExisting")
If (sftp.LastMethodSuccess = False) Then
    Debug.WriteLine(sftp.LastErrorText)
    Exit Sub
End If


Dim bd As New Chilkat.BinData
Dim chunkSize As Integer = 4096
Dim reading As Boolean = True
While reading
    success = sftp.ReadFileBd(handle,chunkSize,bd)
    If (sftp.LastReadFailed(handle)) Then
        Debug.WriteLine(sftp.LastErrorText)
        Exit Sub
    End If


    '  Report how many bytes the last read actually returned.  A normal EOF read reports 0.
    Dim lastCount As Integer = sftp.LastReadNumBytes(handle)
    Debug.WriteLine("Last read returned " & lastCount & " bytes.")

    reading = Not sftp.Eof(handle)
End While

success = sftp.CloseHandle(handle)
If (success = False) Then
    Debug.WriteLine(sftp.LastErrorText)
    Exit Sub
End If

Debug.WriteLine("Total: " & bd.NumBytes & " bytes.")

sftp.Disconnect()