VBScript

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 fso, outFile
Set fso = CreateObject("Scripting.FileSystemObject")
'Create a Unicode (utf-16) output text file.
Set outFile = fso.CreateTextFile("output.txt", True, True)

success = 0

'  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.

set sftp = CreateObject("Chilkat.SFtp")

'  Connect, authenticate, and initialize the SFTP subsystem.
port = 22
success = sftp.Connect("sftp.example.com",port)
If (success = 0) Then
    outFile.WriteLine(sftp.LastErrorText)
    WScript.Quit
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.
password = "mySshPassword"

success = sftp.AuthenticatePw("mySshLogin",password)
If (success = 0) Then
    outFile.WriteLine(sftp.LastErrorText)
    WScript.Quit
End If

success = sftp.InitializeSftp()
If (success = 0) Then
    outFile.WriteLine(sftp.LastErrorText)
    WScript.Quit
End If

handle = sftp.OpenFile("subdir/data.txt","readOnly","openExisting")
If (sftp.LastMethodSuccess = 0) Then
    outFile.WriteLine(sftp.LastErrorText)
    WScript.Quit
End If

set bd = CreateObject("Chilkat.BinData")
chunkSize = 4096
reading = 1
Do While reading
    success = sftp.ReadFileBd(handle,chunkSize,bd)
    If (sftp.LastReadFailed(handle)) Then
        outFile.WriteLine(sftp.LastErrorText)
        WScript.Quit
    End If

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

    reading = Not sftp.Eof(handle)
Loop

success = sftp.CloseHandle(handle)
If (success = 0) Then
    outFile.WriteLine(sftp.LastErrorText)
    WScript.Quit
End If

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

sftp.Disconnect 

outFile.Close