Rust

Resume an Interrupted FTP Transfer

Demonstrates the RestartNext and PartialTransfer properties, which request that the next transfer resume from existing content and report whether a download was incomplete.

Note: The local paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: For a large transfer over a flaky link, restarting from zero after a drop is wasteful. Setting RestartNext makes the next download continue from the current local file size (and the next upload from the remote size); the flag is consumed by that one transfer and then reset. Afterward PartialTransfer tells you whether the download got only part of the file — the signal to set RestartNext again and resume once more.

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Rust


let ftp = chilkat::Ftp2::new();

ftp.set_hostname("ftp.example.com");
ftp.set_username("myFtpLogin");

// 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.
ftp.set_password("myPassword");

if ftp.connect().is_err() {
    println!("{}", ftp.last_error_text());
    return;
}

// RestartNext requests that the NEXT transfer resume from existing content rather than starting
// over.  It is consumed by that transfer and then automatically reset.
ftp.set_restart_next(true);

// Resume a partially-downloaded file.  Because RestartNext is set, the download continues from
// the current local file size.
if ftp.get_file("public_html/bigfile.zip", "qa_output/bigfile.zip").is_err() {
    println!("{}", ftp.last_error_text());
    return;
}

// PartialTransfer indicates whether the most recent download received some, but not all, of the
// remote file -- distinguishing a mid-transfer failure from other outcomes.
if ftp.partial_transfer() {
    println!("Only part of the file was received; another resume may be needed.");
} else {
    println!("The file was fully received.");
}

if ftp.disconnect().is_err() {
    println!("{}", ftp.last_error_text());
    return;
}