PureBasic

SFTP Upload Large File in Parts

See more SFTP Examples

Demonstrates how to split a large file into N parts and then upload each part separately. This technique can be used to potentially avoid limits a SFTP server might impose on upload file size. PureBasic

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

Procedure ChilkatExample()

    success.i = 0

    ; This example assumes the Chilkat API to have been previously unlocked.
    ; See Global Unlock Sample for sample code.

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

    ; Set some timeouts, in milliseconds:
    CkSFtp::setCkConnectTimeoutMs(sftp, 5000)
    CkSFtp::setCkIdleTimeoutMs(sftp, 10000)

    ; Connect to the SSH server.  
    ; The standard SSH port = 22
    ; The hostname may be a hostname or IP address.
    hostname.s = "sftp.example.com"
    port.i = 22
    success = CkSFtp::ckConnect(sftp,hostname,port)
    If success <> 1
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

    ; Authenticate with the SSH server.  Chilkat SFTP supports
    ; both password-based authenication as well as public-key
    ; authentication.  This example uses password authenication.
    success = CkSFtp::ckAuthenticatePw(sftp,"myLogin","myPassword")
    If success <> 1
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

    ; After authenticating, the SFTP subsystem must be initialized:
    success = CkSFtp::ckInitializeSftp(sftp)
    If success <> 1
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

    ; Open a remote file for writing on the SSH server.
    ; If the file already exists, it is overwritten.
    ; (Specify "createNew" instead of "createTruncate" to
    ; prevent overwriting existing files.)
    handle.s = CkSFtp::ckOpenFile(sftp,"big.zip","writeOnly","createTruncate")
    If CkSFtp::ckLastMethodSuccess(sftp) <> 1
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        ProcedureReturn
    EndIf

    ; We're going to upload the local file "qa_data/zips/big.zip" (a relative local path from our current working directory)
    ; to the SFTP server.
    localFilePath.s = "qa_data/zips/big.zip"

    ; Rather than uploading in one shot, we'll read the local file in chunks
    ; and upload a chunk at a time.
    fac.i = CkFileAccess::ckCreate()
    If fac.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkFileAccess::ckOpenForRead(fac,localFilePath)
    If success = 0
        CkSFtp::ckCloseHandle(sftp,handle)
        Debug CkFileAccess::ckLastErrorText(fac)
        CkSFtp::ckDispose(sftp)
        CkFileAccess::ckDispose(fac)
        ProcedureReturn
    EndIf

    ; If we were to split the local file into 128K chunks, how many chunks (blocks) would
    ; we have, including the last partial block?
    blockSize.i = 131072
    numBlocks.i = CkFileAccess::ckGetNumBlocks(fac,blockSize)
    Debug "Number of blocks = " + Str(numBlocks)

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

    i.i = 0
    While i < numBlocks
        ; Read the Nth block, which gets appended to the bd.  (which means
        ; we must clear the contents of bd before the next iteration)
        success = CkFileAccess::ckReadBlockBd(fac,i,blockSize,bd)
        If success = 0
            CkSFtp::ckCloseHandle(sftp,handle)
            Debug CkFileAccess::ckLastErrorText(fac)
            CkSFtp::ckDispose(sftp)
            CkFileAccess::ckDispose(fac)
            CkBinData::ckDispose(bd)
            ProcedureReturn
        EndIf

        ; Upload this block to the open remote file.
        success = CkSFtp::ckWriteFileBd(sftp,handle,bd)
        If success = 0
            Debug CkSFtp::ckLastErrorText(sftp)
            CkSFtp::ckDispose(sftp)
            CkFileAccess::ckDispose(fac)
            CkBinData::ckDispose(bd)
            ProcedureReturn
        EndIf

        ; Clear the contents for the next iteration.
        CkBinData::ckClear(bd)

        i = i + 1
    Wend

    ; Close the local file.
    CkFileAccess::ckFileClose(fac)

    ; -----------------------------------------------------------------------------
    ; This is important.  You must close the handle on the server.
    ; Otherwise open handles will accumulate on the server until eventually a limit
    ; is reached and the server will fail on a call to OpenFile.
    ; -----------------------------------------------------------------------------

    ; Close the remote file handle on the server.
    success = CkSFtp::ckCloseHandle(sftp,handle)
    If success <> 1
        Debug CkSFtp::ckLastErrorText(sftp)
        CkSFtp::ckDispose(sftp)
        CkFileAccess::ckDispose(fac)
        CkBinData::ckDispose(bd)
        ProcedureReturn
    EndIf

    Debug "Success."


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


    ProcedureReturn
EndProcedure