Question

I am using the Ganymed API to sftp in to an Unix server . I am able to create the file in server, but the contents of the file is always empty.

Ganymed API location:
http://www.ganymed.ethz.ch/ssh2/

Code:

  function (ByteArrayOutputStream reportBytes){
 // reportBytes is a valid ByteArrayOutputStream
 // if I write it to a file in to a local directory using reportBytes.writeTo(fout); 
 // I can see the contents */

 byte byteArray[]=reportBytes.toByteArray();

 SFTPv3FileHandle SFTPFILEHandle=sftpClient.createFileTruncate("test.txt");
 //The file is created successfully and it is listed in unix 
 // The permissions of the file -rw-r--r-- 1 test.txt


 sftpClient.write(SFTPFILEHandle, 0, byteArray, 0,byteArray.length );
 //The above line doesnt seem to work, the file is always empty
 }

 /* write function definition is */
 public void write(SFTPv3FileHandle handle, long fileOffset, byte[] src, int srcoff, int len) throws IOException

Can someone tell me if I am doing something wrong here

Answer 1

I tried to solve your problem, and I ended up in the same situation, the created file remains empty.

However, I think I found the cause of the problem.

Here is an extract of the ch.ethz.ssh2.SFTPv3Client.write() method of ganymed API

    /**
 * Write bytes to a file. If <code>len</code> &gt; 32768, then the write operation will
 * be split into multiple writes.
 * 
 * @param handle a SFTPv3FileHandle handle.
 * @param fileOffset offset (in bytes) in the file.
 * @param src the source byte array.
 * @param srcoff offset in the source byte array.
 * @param len how many bytes to write.
 * @throws IOException
 */
public void write(SFTPv3FileHandle handle, long fileOffset, byte[] src, int srcoff, int len) throws IOException
{
    checkHandleValidAndOpen(handle);

    if (len < 0)

        while (len > 0)
        {

You see, when you send data to write, len is > 0, and because of the bogus condition, the method returns right away, and it never enters the while loop (that actually write something to the file).

I guess there was a statement right after the “if (len < 0)” before, but someone took it away and left us with useless piece of code…

Update :

Go get the latest version (The example above was using build 210).
I had no problem with the build 250 and 251.

Here’s my code, and it’s writing correctly to a new file on my ssh server.

you will need to bulletproof this 🙂

    public static void main(String[] args) throws Exception {
        Connection conn = new Connection(hostname);
        conn.connect();
        boolean isAuthenticated = conn.authenticateWithPassword(username, password);

        if (isAuthenticated == false)
            throw new IOException("Authentication failed.");
        SFTPv3Client client = new SFTPv3Client(conn);
        File tmpFile = File.createTempFile("teststackoverflow", "dat");
        FileWriter fw = new FileWriter(tmpFile);
        fw.write("this is a test");
        fw.flush();
        fw.close();

        SFTPv3FileHandle handle = client.createFile(tmpFile.getName());
        FileInputStream fis = new FileInputStream(tmpFile); 
        byte[] buffer = new byte[1024];
        int i=0;
                    long offset=0;
        while ((i = fis.read(buffer)) != -1) {
            client.write(handle,offset,buffer,0,i);
                            offset+= i;

        }
        client.closeFile(handle);
        if (handle.isClosed())  System.out.println("closed");;
        client.close();
}