Dart

Detect End-of-File on a Remote SFTP File

Demonstrates the Chilkat SFtp.Eof method, which returns whether the most recent read for a handle received the SFTP end-of-file status. The only argument is the handle. This example reads until Eof is true.

Background: The timing here is worth understanding: reading exactly through the final byte does not immediately set EOF. The next read succeeds, returns zero bytes, sets the status to SSH_FX_EOF, and only then does Eof report true. That is why the loop tests Eof after each read rather than assuming a short read means the end — a short read can also just be the server returning less than requested.

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Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // Demonstrates the SFtp.Eof method, which returns whether the most recent read for a handle
  // received the SFTP end-of-file status.  The only argument is the handle.

  final sftp = CkSFtp();

  // Connect, authenticate, and initialize the SFTP subsystem.
  final port = 22;
  try {
    sftp.connect('sftp.example.com', port);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // 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.
  final password = 'mySshPassword';

  try {
    sftp.authenticatePw('mySshLogin', password);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  try {
    sftp.initializeSftp();
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final String handle;
  try {
    handle = sftp.openFile('subdir/data.txt', 'readOnly', 'openExisting');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Read until Eof reports the end of the file.  Note that reading exactly through the final byte
  // does not set EOF; the next read returns zero bytes and then Eof becomes true.
  final sbContent = CkStringBuilder();
  final chunkSize = 4096;
  var reading = true;
  while (reading) {
    final chunk = sftp.readFileText(handle, chunkSize, 'utf-8');
    if (sftp.lastReadFailed(handle)) {
      print(sftp.lastErrorText);
      return;
    }

    sbContent.append(chunk);
    reading = !sftp.eof(handle);
  }

  try {
    sftp.closeHandle(handle);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print(sbContent.getAsString());

  sftp.disconnect();
}