UnsupportedOperationException in NativeSshFile.setAttributes when uploading files Apache Mina sshd Server

Question

I start up a local SFTP server using Apache Mina SSHD. Here is my related code. To testing I use WinSCP as my SFTP client. I can connect to the server successfully and can view server root directory also. But the problem was that when I try to upload a file into that server root directory.

I got a

Exception caught in SFTP subsystem
java.lang.UnsupportedOperationException: null 
at org.apache.sshd.common.file.nativefs.NativeSshFile.setAttributes(NativeSshFile.java:634) ~[sshd-core-0.10.0.jar:0.10.0]
    at org.apache.sshd.server.sftp.SftpSubsystem.process(SftpSubsystem.java:427) ~[sshd-core-0.10.0.jar:0.10.0]
    at org.apache.sshd.server.sftp.SftpSubsystem.run(SftpSubsystem.java:334) ~[sshd-core-0.10.0.jar:0.10.0]
    at java.lang.Thread.run(Unknown Source) [na:1.7.0_75].

Below is my related log files.

10:30:46.758 [Thread-1] DEBUG o.a.s.c.file.nativefs.NativeSshFile - Authorized
10:30:46.767 [Thread-1] ERROR o.a.sshd.server.sftp.SftpSubsystem - Exception caught in SFTP subsystem
java.lang.UnsupportedOperationException: null
    at org.apache.sshd.common.file.nativefs.NativeSshFile.setAttributes(NativeSshFile.java:634) ~[sshd-core-0.10.0.jar:0.10.0]
    at org.apache.sshd.server.sftp.SftpSubsystem.process(SftpSubsystem.java:427) ~[sshd-core-0.10.0.jar:0.10.0]
    at org.apache.sshd.server.sftp.SftpSubsystem.run(SftpSubsystem.java:334) ~[sshd-core-0.10.0.jar:0.10.0]
    at java.lang.Thread.run(Unknown Source) [na:1.7.0_75]
10:30:46.767 [Thread-1] DEBUG o.a.s.server.channel.ChannelSession - Send SSH_MSG_CHANNEL_EOF on channel ChannelSession[id=0, recipient=256]
10:30:46.768 [Thread-1] DEBUG o.a.sshd.common.io.nio2.Nio2Session - Writing 64 bytes

Also my maven dependency,

<dependency>
    <groupId>org.apache.mina</groupId>
    <artifactId>mina-core</artifactId>
    <version>2.0.9</version>
</dependency>
<dependency>
    <groupId>org.apache.sshd</groupId>
    <artifactId>sshd-sftp</artifactId>
    <version>0.9.0</version>
</dependency>
<dependency>
    <groupId>org.apache.sshd</groupId>
    <artifactId>sshd-core</artifactId>
    <version>0.10.0</version>
</dependency>

I would like to know that how can I overcome above problem when uploading files into my local SFTP server. Thanks.

score 1 · Accepted Answer · answered Apr 22 '15 at 06:10

When uploading files, WinSCP, depending on its configuration, sets uploaded file timestamp (on by default) and/or permissions (off by default).

The Mina SSHD 0.10.0 does not support setting file attributes.

public void setAttributes(Map<Attribute, Object> attributes) throws IOException {
    if (!attributes.isEmpty()) {
        throw new UnsupportedOperationException();
    }
}

The latest Mina SSHD 0.14.0 does support setting the timestamp and by default only logs that it cannot set the permissions (or other attributes).

public void setAttributes(Map<Attribute, Object> attributes) throws IOException {
    Set<Attribute> unsupported = new HashSet<Attribute>();
    for (Attribute attribute : attributes.keySet()) {
        Object value = attributes.get(attribute);
        switch (attribute) {
        case Size: {
            long newSize = (Long) value;
            FileChannel outChan = new FileOutputStream(file, true).getChannel();
            outChan.truncate(newSize);
            outChan.close();
            continue;
        }
        case LastModifiedTime:
            setLastModified((Long) value);
            break;
        default:
            unsupported.add(attribute);
            break;
        }
    }
    handleUnsupportedAttributes(unsupported);
}

protected void handleUnsupportedAttributes(Collection<Attribute> attributes) {
    if (!attributes.isEmpty()) {
        StringBuilder sb = new StringBuilder();
        for (Attribute attr : attributes) {
            if (sb.length() > 0) {
                sb.append(", ");
            }
            sb.append(attr.name());
        }
        switch (nativeFileSystemView.getUnsupportedAttributePolicy()) {
        case Ignore:
            break;
        case Warn:
            LOG.warn("Unsupported attributes: " + sb.toString());
            break;
        case ThrowException:
            throw new UnsupportedOperationException("Unsupported attributes: " + sb.toString());
        }
    }
}

Thanks @Martin Prikryl.But the problem is that i changed the **sshd-core** 0.10.0 into 0.14.0 version but some of override methods are not provided there to set up root directory.eg : ** sshd.setFileSystemFactory(new NativeFileSystemFactory() { Override public FileSystemView createFileSystemView(final Session session) { return new NativeFileSystemView(session.getUsername(), false) { Override public String getVirtualUserDir() { return "C:/rootdirectory"; } }; }; }); ** — gihan-maduranga, Apr 22 '15 at 06:22
But that's irrelevant to this question. If you have a problem with overriding methods of `NativeFileSystemView` in 0.14.0, ask a separate question on that. I believe this question is answered. — Martin Prikryl, Apr 22 '15 at 06:29
Yes @Martin Prikryl that was my previous question to setup root in Apache mina.That answer only works for 0.10.0 version.But can not apply into 0.14.0 version.(There is no override methods implementation on getVirtualUserDir() ). http://stackoverflow.com/questions/29389249/how-to-set-root-directory-in-apache-mina-sshd-server-in-java I will rise a new question for version 0.14.0.Thanks Martin for your help. — gihan-maduranga, Apr 22 '15 at 06:40
FYI.http://stackoverflow.com/questions/29789995/how-to-override-getvirtualuserdir-in-apache-mina-sshd-core-version-0-14-0 Thanks. — gihan-maduranga, Apr 22 '15 at 06:59

UnsupportedOperationException in NativeSshFile.setAttributes when uploading files Apache Mina sshd Server

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