(Go) 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.

Chilkat Go Downloads Go Package for Windows, MacOS, Linux, Alpine Linux, Solaris

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

    sftp := chilkat.NewSFtp()

    // Set some timeouts, in milliseconds:
    sftp.SetConnectTimeoutMs(5000)
    sftp.SetIdleTimeoutMs(10000)

    // Connect to the SSH server.  
    // The standard SSH port = 22
    // The hostname may be a hostname or IP address.
    hostname := "sftp.example.com"
    port := 22
    success := sftp.Connect(hostname,port)
    if success != true {
        fmt.Println(sftp.LastErrorText())
        sftp.DisposeSFtp()
        return
    }

    // Authenticate with the SSH server.  Chilkat SFTP supports
    // both password-based authenication as well as public-key
    // authentication.  This example uses password authenication.
    success = sftp.AuthenticatePw("myLogin","myPassword")
    if success != true {
        fmt.Println(sftp.LastErrorText())
        sftp.DisposeSFtp()
        return
    }

    // After authenticating, the SFTP subsystem must be initialized:
    success = sftp.InitializeSftp()
    if success != true {
        fmt.Println(sftp.LastErrorText())
        sftp.DisposeSFtp()
        return
    }

    // 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 := sftp.OpenFile("big.zip","writeOnly","createTruncate")
    if sftp.LastMethodSuccess() != true {
        fmt.Println(sftp.LastErrorText())
        sftp.DisposeSFtp()
        return
    }

    // 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 := "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 := chilkat.NewFileAccess()

    success = fac.OpenForRead(localFilePath)
    if success == false {
        sftp.CloseHandle(*handle)
        fmt.Println(fac.LastErrorText())
        sftp.DisposeSFtp()
        fac.DisposeFileAccess()
        return
    }

    // If we were to split the local file into 128K chunks, how many chunks (blocks) would
    // we have, including the last partial block?
    blockSize := 131072
    numBlocks := fac.GetNumBlocks(blockSize)
    fmt.Println("Number of blocks = ", numBlocks)

    bd := chilkat.NewBinData()
    i := 0
    for 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 = fac.ReadBlockBd(i,blockSize,bd)
        if success == false {
            sftp.CloseHandle(*handle)
            fmt.Println(fac.LastErrorText())
            sftp.DisposeSFtp()
            fac.DisposeFileAccess()
            bd.DisposeBinData()
            return
        }

        // Upload this block to the open remote file.
        success = sftp.WriteFileBd(*handle,bd)
        if success == false {
            fmt.Println(sftp.LastErrorText())
            sftp.DisposeSFtp()
            fac.DisposeFileAccess()
            bd.DisposeBinData()
            return
        }

        // Clear the contents for the next iteration.
        bd.Clear()

        i = i + 1
    }

    // Close the local file.
    fac.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.
    success = sftp.CloseHandle(*handle)
    if success != true {
        fmt.Println(sftp.LastErrorText())
        sftp.DisposeSFtp()
        fac.DisposeFileAccess()
        bd.DisposeBinData()
        return
    }

    fmt.Println("Success.")

    sftp.DisposeSFtp()
    fac.DisposeFileAccess()
    bd.DisposeBinData()