Classic ASP

Check Whether the Last SFTP Read Failed

Demonstrates the Chilkat SFtp.LastReadFailed method, which returns whether the most recent read for a handle failed. The only argument is the handle. A normal end-of-file is not a failure.

Background: A chunked read loop needs to tell three outcomes apart: more data, a clean end-of-file, and an actual error such as a dropped connection or a revoked handle. LastReadFailed isolates the error case — it is false on a normal EOF read (which succeeds with zero bytes) and true for an empty, malformed, or already-closed handle — so the loop can stop cleanly on EOF but bail out with an error message on a genuine failure.

Chilkat Classic ASP Downloads

Download Chilkat for Classic ASP

Classic ASP

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
success = 0

'  Demonstrates the SFtp.LastReadFailed method, which returns whether the most recent read for a
'  handle failed.  The only argument is the handle.  A normal end-of-file is NOT a failure.

set sftp = Server.CreateObject("Chilkat.SFtp")

'  Connect, authenticate, and initialize the SFTP subsystem.
port = 22
success = sftp.Connect("sftp.example.com",port)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( sftp.LastErrorText) & "</pre>"
    Response.End
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
    Response.Write "<pre>" & Server.HTMLEncode( sftp.LastErrorText) & "</pre>"
    Response.End
End If

success = sftp.InitializeSftp()
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( sftp.LastErrorText) & "</pre>"
    Response.End
End If

handle = sftp.OpenFile("subdir/data.txt","readOnly","openExisting")
If (sftp.LastMethodSuccess = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( sftp.LastErrorText) & "</pre>"
    Response.End
End If

reading = 1
chunkSize = 4096
set bd = Server.CreateObject("Chilkat.BinData")
Do While reading
    success = sftp.ReadFileBd(handle,chunkSize,bd)

    '  Distinguish an actual read failure from a normal EOF.  On EOF the read succeeds, returns
    '  zero bytes, and LastReadFailed is 0.
    If (sftp.LastReadFailed(handle)) Then
        Response.Write "<pre>" & Server.HTMLEncode( "Read failed: " & sftp.LastErrorText) & "</pre>"
        Response.End
    End If

    reading = Not sftp.Eof(handle)
Loop

success = sftp.CloseHandle(handle)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( sftp.LastErrorText) & "</pre>"
    Response.End
End If

Response.Write "<pre>" & Server.HTMLEncode( "Read " & bd.NumBytes & " bytes with no read failures.") & "</pre>"

sftp.Disconnect 

%>
</body>
</html>