Android™

Check Whether the Last SFTP Read Failed

Demonstrates the Chilkat SFtp.LastReadFailed method, which returns whether the most recent read for a handle failed. The only argument is the handle. A normal end-of-file is not a failure.

Background: A chunked read loop needs to tell three outcomes apart: more data, a clean end-of-file, and an actual error such as a dropped connection or a revoked handle. LastReadFailed isolates the error case — it is false on a normal EOF read (which succeeds with zero bytes) and true for an empty, malformed, or already-closed handle — so the loop can stop cleanly on EOF but bail out with an error message on a genuine failure.

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// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    boolean success = false;

    //  Demonstrates the SFtp.LastReadFailed method, which returns whether the most recent read for a
    //  handle failed.  The only argument is the handle.  A normal end-of-file is NOT a failure.

    CkSFtp sftp = new CkSFtp();

    //  Connect, authenticate, and initialize the SFTP subsystem.
    int port = 22;
    success = sftp.Connect("sftp.example.com",port);
    if (success == false) {
        Log.i(TAG, sftp.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.
    String password = "mySshPassword";

    success = sftp.AuthenticatePw("mySshLogin",password);
    if (success == false) {
        Log.i(TAG, sftp.lastErrorText());
        return;
        }

    success = sftp.InitializeSftp();
    if (success == false) {
        Log.i(TAG, sftp.lastErrorText());
        return;
        }

    String handle = sftp.openFile("subdir/data.txt","readOnly","openExisting");
    if (sftp.get_LastMethodSuccess() == false) {
        Log.i(TAG, sftp.lastErrorText());
        return;
        }

    boolean reading = true;
    int chunkSize = 4096;
    CkBinData bd = new CkBinData();
    while (reading) {
        success = sftp.ReadFileBd(handle,chunkSize,bd);

        //  Distinguish an actual read failure from a normal EOF.  On EOF the read succeeds, returns
        //  zero bytes, and LastReadFailed is false.
        if (sftp.LastReadFailed(handle)) {
            Log.i(TAG, "Read failed: " + sftp.lastErrorText());
            return;
            }

        reading = !sftp.Eof(handle);
        }

    success = sftp.CloseHandle(handle);
    if (success == false) {
        Log.i(TAG, sftp.lastErrorText());
        return;
        }

    Log.i(TAG, "Read " + String.valueOf(bd.get_NumBytes()) + " bytes with no read failures.");

    sftp.Disconnect();

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}