(Swift 3,4,5...) SFTP Upload Large File in Parts

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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 Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

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

    let sftp = CkoSFtp()!

    // Set some timeouts, in milliseconds:
    sftp.connectTimeoutMs = 5000
    sftp.idleTimeoutMs = 10000

    // Connect to the SSH server.  
    // The standard SSH port = 22
    // The hostname may be a hostname or IP address.
    var hostname: String? = "sftp.example.com"
    var port: Int = 22
    var success: Bool = sftp.connect(hostname, port: port)
    if success != true {
        print("\(sftp.lastErrorText!)")
        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", password: "myPassword")
    if success != true {
        print("\(sftp.lastErrorText!)")
        return
    }

    // After authenticating, the SFTP subsystem must be initialized:
    success = sftp.initializeSftp()
    if success != true {
        print("\(sftp.lastErrorText!)")
        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.)
    var handle: String? = sftp.openFile("big.zip", access: "writeOnly", createDisp: "createTruncate")
    if sftp.lastMethodSuccess != true {
        print("\(sftp.lastErrorText!)")
        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.
    var localFilePath: String? = "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.
    let fac = CkoFileAccess()!

    success = fac.open(forRead: localFilePath)
    if success == false {
        sftp.closeHandle(handle)
        print("\(fac.lastErrorText!)")
        return
    }

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

    let bd = CkoBinData()!
    var i: Int = 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 = fac.readBlockBd(i, blockSize: blockSize, bd: bd)
        if success == false {
            sftp.closeHandle(handle)
            print("\(fac.lastErrorText!)")
            return
        }

        // Upload this block to the open remote file.
        success = sftp.writeFileBd(handle, bd: bd)
        if success == false {
            print("\(sftp.lastErrorText!)")
            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 {
        print("\(sftp.lastErrorText!)")
        return
    }

    print("Success.")

}