Visual FoxPro

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. Visual FoxPro

LOCAL lnSuccess
LOCAL loSftp
LOCAL lcHostname
LOCAL lnPort
LOCAL lcHandle
LOCAL lcLocalFilePath
LOCAL loFac
LOCAL lnBlockSize
LOCAL lnNumBlocks
LOCAL loBd
LOCAL i

lnSuccess = 0

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

loSftp = CreateObject('Chilkat.SFtp')

* Set some timeouts, in milliseconds:
loSftp.ConnectTimeoutMs = 5000
loSftp.IdleTimeoutMs = 10000

* Connect to the SSH server.  
* The standard SSH port = 22
* The hostname may be a hostname or IP address.
lcHostname = "sftp.example.com"
lnPort = 22
lnSuccess = loSftp.Connect(lcHostname,lnPort)
IF (lnSuccess <> 1) THEN
    ? loSftp.LastErrorText
    RELEASE loSftp
    CANCEL
ENDIF

* Authenticate with the SSH server.  Chilkat SFTP supports
* both password-based authenication as well as public-key
* authentication.  This example uses password authenication.
lnSuccess = loSftp.AuthenticatePw("myLogin","myPassword")
IF (lnSuccess <> 1) THEN
    ? loSftp.LastErrorText
    RELEASE loSftp
    CANCEL
ENDIF

* After authenticating, the SFTP subsystem must be initialized:
lnSuccess = loSftp.InitializeSftp()
IF (lnSuccess <> 1) THEN
    ? loSftp.LastErrorText
    RELEASE loSftp
    CANCEL
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.)
lcHandle = loSftp.OpenFile("big.zip","writeOnly","createTruncate")
IF (loSftp.LastMethodSuccess <> 1) THEN
    ? loSftp.LastErrorText
    RELEASE loSftp
    CANCEL
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.
lcLocalFilePath = "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.
loFac = CreateObject('Chilkat.FileAccess')

lnSuccess = loFac.OpenForRead(lcLocalFilePath)
IF (lnSuccess = 0) THEN
    loSftp.CloseHandle(lcHandle)
    ? loFac.LastErrorText
    RELEASE loSftp
    RELEASE loFac
    CANCEL
ENDIF

* If we were to split the local file into 128K chunks, how many chunks (blocks) would
* we have, including the last partial block?
lnBlockSize = 131072
lnNumBlocks = loFac.GetNumBlocks(lnBlockSize)
? "Number of blocks = " + STR(lnNumBlocks)

loBd = CreateObject('Chilkat.BinData')
i = 0
DO WHILE i < lnNumBlocks
    * Read the Nth block, which gets appended to the bd.  (which means
    * we must clear the contents of bd before the next iteration)
    lnSuccess = loFac.ReadBlockBd(i,lnBlockSize,loBd)
    IF (lnSuccess = 0) THEN
        loSftp.CloseHandle(lcHandle)
        ? loFac.LastErrorText
        RELEASE loSftp
        RELEASE loFac
        RELEASE loBd
        CANCEL
    ENDIF

    * Upload this block to the open remote file.
    lnSuccess = loSftp.WriteFileBd(lcHandle,loBd)
    IF (lnSuccess = 0) THEN
        ? loSftp.LastErrorText
        RELEASE loSftp
        RELEASE loFac
        RELEASE loBd
        CANCEL
    ENDIF

    * Clear the contents for the next iteration.
    loBd.Clear()

    i = i + 1
ENDDO

* Close the local file.
loFac.FileClose()

* -----------------------------------------------------------------------------
* 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.
lnSuccess = loSftp.CloseHandle(lcHandle)
IF (lnSuccess <> 1) THEN
    ? loSftp.LastErrorText
    RELEASE loSftp
    RELEASE loFac
    RELEASE loBd
    CANCEL
ENDIF

? "Success."

RELEASE loSftp
RELEASE loFac
RELEASE loBd