VB.NET

Write Text at a 64-bit Offset in a Remote SFTP File

Demonstrates the Chilkat SFtp.WriteFileText64 method, which encodes text and writes it at a specific 64-bit byte offset in an open handle. The arguments are the handle, the offset, the charset, and the text. The 64-bit offset supports very large files.

Background: A 32-bit offset tops out at about 4 GB, so files larger than that require the 64-bit form to address positions beyond that boundary. The behavior is otherwise identical to the 32-bit version — the only difference is the width of the offset argument, chosen to match the size of the file you are working with.

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Dim success As Boolean = False

'  Demonstrates the SFtp.WriteFileText64 method, which encodes text and writes it at a specific
'  64-bit byte offset in an open handle.  The 1st argument is the handle, the 2nd is the offset,
'  the 3rd is the charset, and the 4th is the text.  The 64-bit offset supports very large files.

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/hugefile.dat","readWrite","openOrCreate")
If (sftp.LastMethodSuccess = False) Then
    Debug.WriteLine(sftp.LastErrorText)
    Exit Sub
End If


'  Write at a byte offset beyond the 32-bit (4 GB) range.
Dim offset As Long = 5000000000
success = sftp.WriteFileText64(handle,offset,"utf-8","MARKER")
If (success = False) Then
    Debug.WriteLine(sftp.LastErrorText)
    Exit Sub
End If


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

Debug.WriteLine("Wrote at the 64-bit offset.")

sftp.Disconnect()