PureBasic

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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IncludeFile "CkBinData.pb"
IncludeFile "CkSFtp.pb"

Procedure ChilkatExample()

    success.i = 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.

    sftp.i = CkSFtp::ckCreate()
    If sftp.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ;  Connect, authenticate, and initialize the SFTP subsystem.
    port.i = 22
    success = CkSFtp::ckConnect(sftp,"sftp.example.com",port)
    If success = 0
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

    ;  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.s = "mySshPassword"

    success = CkSFtp::ckAuthenticatePw(sftp,"mySshLogin",password)
    If success = 0
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

    success = CkSFtp::ckInitializeSftp(sftp)
    If success = 0
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

    handle.s = CkSFtp::ckOpenFile(sftp,"subdir/data.txt","readOnly","openExisting")
    If CkSFtp::ckLastMethodSuccess(sftp) = 0
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

    bd.i = CkBinData::ckCreate()
    If bd.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    chunkSize.i = 4096
    reading.i = 1
    While reading
        success = CkSFtp::ckReadFileBd(sftp,handle,chunkSize,bd)
        If CkSFtp::ckLastReadFailed(sftp,handle)
            Debug CkSFtp::ckLastErrorText(sftp)
            CkSFtp::ckDispose(sftp)
            CkBinData::ckDispose(bd)
            ProcedureReturn
        EndIf

        ;  Report how many bytes the last read actually returned.  A normal EOF read reports 0.
        lastCount.i = CkSFtp::ckLastReadNumBytes(sftp,handle)
        Debug "Last read returned " + Str(lastCount) + " bytes."

        reading = Not CkSFtp::ckEof(sftp,handle)
    Wend

    success = CkSFtp::ckCloseHandle(sftp,handle)
    If success = 0
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        CkBinData::ckDispose(bd)
        ProcedureReturn
    EndIf

    Debug "Total: " + Str(CkBinData::ckNumBytes(bd)) + " bytes."

    CkSFtp::ckDisconnect(sftp)


    CkSFtp::ckDispose(sftp)
    CkBinData::ckDispose(bd)


    ProcedureReturn
EndProcedure