VB.NET

Detect End-of-File on a Remote SFTP File

Demonstrates the Chilkat SFtp.Eof method, which returns whether the most recent read for a handle received the SFTP end-of-file status. The only argument is the handle. This example reads until Eof is true.

Background: The timing here is worth understanding: reading exactly through the final byte does not immediately set EOF. The next read succeeds, returns zero bytes, sets the status to SSH_FX_EOF, and only then does Eof report true. That is why the loop tests Eof after each read rather than assuming a short read means the end — a short read can also just be the server returning less than requested.

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Dim success As Boolean = False

'  Demonstrates the SFtp.Eof method, which returns whether the most recent read for a handle
'  received the SFTP end-of-file status.  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


'  Read until Eof reports the end of the file.  Note that reading exactly through the final byte
'  does not set EOF; the next read returns zero bytes and then Eof becomes true.
Dim sbContent As New Chilkat.StringBuilder
Dim chunkSize As Integer = 4096
Dim reading As Boolean = True
While reading
    Dim chunk As String = sftp.ReadFileText(handle,chunkSize,"utf-8")
    If (sftp.LastReadFailed(handle)) Then
        Debug.WriteLine(sftp.LastErrorText)
        Exit Sub
    End If

    sbContent.Append(chunk)
    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(sbContent.GetAsString())

sftp.Disconnect()