Dart

Pre-Allocate Server Space Before an FTP Upload (ALLO)

Demonstrates the AllocateSize property, which sends the FTP ALLO command to pre-allocate disk space on the server before an upload. Set it to the size in bytes of the file about to be uploaded.

Background: ALLO asks the server to reserve storage in advance, a requirement of certain legacy systems — older mainframes in particular — that need the exact file size up front to allocate a dataset. Modern servers allocate space dynamically and typically ignore or accept ALLO without needing it, so most applications never set this. Provide it only when targeting a host known to require pre-allocation.

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Dart

import 'package:chilkat/chilkat.dart';

void main() {
  final ftp = CkFtp2();

  ftp.hostname = 'ftp.example.com';
  ftp.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.password = 'myPassword';

  try {
    ftp.connect();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // AllocateSize sends the FTP ALLO command to pre-allocate disk space on the server before an
  // upload.  It is rarely needed -- mainly for certain legacy systems that require the exact size
  // in advance -- since most servers allocate space dynamically.  Set it to the size in bytes of
  // the file about to be uploaded.
ERROR: Assignment type mismatch.  ExpressionType=int, atgType=uint

  try {
    ftp.putFile('qa_data/bigfile.zip', 'uploads/bigfile.zip');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Uploaded with pre-allocation.');

  try {
    ftp.disconnect();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }
}