Xojo Plugin

Read Text from a Remote SFTP File (Sequential)

Demonstrates the Chilkat SFtp.ReadFileText method, which reads up to a number of bytes from the current position of an open handle and decodes them to text. The arguments are the handle, the maximum number of bytes, and the charset. This example reads in chunks until end-of-file.

Background: Reading a file in bounded chunks keeps memory use predictable regardless of file size, which is why the loop reads a fixed amount and repeats until Eof. A subtlety worth knowing: the byte limit is applied to the encoded bytes, so a chunk boundary could in principle fall in the middle of a multibyte character — accumulating the pieces and decoding the whole avoids any such issue in practice here since the text is reassembled in a StringBuilder.

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Dim success As Boolean
success = False

//  Demonstrates the SFtp.ReadFileText method, which reads up to a number of bytes from the current
//  position of an open handle and decodes them to text.  The 1st argument is the handle, the 2nd
//  is the maximum number of bytes, and the 3rd is the charset.

Dim sftp As New Chilkat.SFtp

//  Connect, authenticate, and initialize the SFTP subsystem.
Dim port As Int32
port = 22
success = sftp.Connect("sftp.example.com",port)
If (success = False) Then
    System.DebugLog(sftp.LastErrorText)
    Return
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
password = "mySshPassword"

success = sftp.AuthenticatePw("mySshLogin",password)
If (success = False) Then
    System.DebugLog(sftp.LastErrorText)
    Return
End If

success = sftp.InitializeSftp()
If (success = False) Then
    System.DebugLog(sftp.LastErrorText)
    Return
End If

//  Open the remote file for reading.
Dim handle As String
handle = sftp.OpenFile("subdir/notes.txt","readOnly","openExisting")
If (sftp.LastMethodSuccess = False) Then
    System.DebugLog(sftp.LastErrorText)
    Return
End If

//  Read the file in chunks until end-of-file, accumulating the text.
Dim sbContent As New Chilkat.StringBuilder
Dim chunkSize As Int32
chunkSize = 4096
Dim reading As Boolean
reading = True
While reading
    Dim chunk As String
    chunk = sftp.ReadFileText(handle,chunkSize,"utf-8")
    If (sftp.LastReadFailed(handle)) Then
        System.DebugLog(sftp.LastErrorText)
        Return
    End If

    success = sbContent.Append(chunk)

    //  Stop once the end of the file has been reached.
    reading = Not sftp.Eof(handle)
Wend

success = sftp.CloseHandle(handle)
If (success = False) Then
    System.DebugLog(sftp.LastErrorText)
    Return
End If

System.DebugLog(sbContent.GetAsString())

sftp.Disconnect