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From "Syed Aqeel Ashiq (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (VFS-651) SftpFileSystem Should not switch to root directory when not absolutely needed
Date Fri, 16 Feb 2018 11:59:00 GMT

    [ https://issues.apache.org/jira/browse/VFS-651?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16366899#comment-16366899
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Syed Aqeel Ashiq commented on VFS-651:
--------------------------------------

[~ottobackwards] Thanks for your time an input. Really appreciated. It might be working as
designed, but as I said it is flawed design.

> SftpFileSystem Should not switch to root directory when not absolutely needed
> -----------------------------------------------------------------------------
>
>                 Key: VFS-651
>                 URL: https://issues.apache.org/jira/browse/VFS-651
>             Project: Commons VFS
>          Issue Type: Bug
>    Affects Versions: 2.0
>            Reporter: Syed Aqeel Ashiq
>            Priority: Major
>             Fix For: 2.3
>
>
> Consider a user X only has read/write access to let's say /sftp and /sftp/abc directory
on a sftp server. And default directory for user is /sftp
> In this case, we have to set userDirIsRoot to false, and thus vfs will try to switch
to root directory, which will fail due to lack of read permission.
> Consider following code:
> {code:java}
>   public void uploadFile(String localFilePath) throws FileSystemException {    
>     FileSystemManager manager = VFS.getManager();
>     FileObject localFile = manager.resolveFile(localFilePath);
>     FileSystemOptions opts = new FileSystemOptions();
>     SftpFileSystemConfigBuilder.getInstance().setUserDirIsRoot(opts, false);
>     // I set it to false,
>     // because user default dir is /sftp and it is obviously not root directory.
>     // As a workaround, If I set it to true, it will work after also tweaking with
>     // the file path while resolving a file, but semantics will be wrong, since 
>     // the user directory is not root.
>     SftpFileSystemConfigBuilder.getInstance().setTimeout(opts, 90000);
>     String remoteFilePath = "sftp://myuser:mypass@myurl.sftpexample.com/sftp/abc/abc.txt";
>     // Exception at the following line
>     FileObject remoteFile = manager.resolveFile(remoteFilePath, opts);
>     // Exception at the line above line. Because this line tries to switch to 
>     // root directory of sftp file system, whichfails due to lack of read 
>     // permission on root directory. Switching to root directory is not 
>     // needed here at all. This is bug, although it works in most scenarios,
>     // since most of times, permissions are available.
>     remoteFile.copyFrom(localFile, Selectors.SELECT_SELF);
>   }
> {code}
> This is the underlying code responsible in
> {code:java}
> org.apache.commons.vfs.provider.sftp.SftpFileSystem
> {code}
> :
> {code:java}
> Boolean userDirIsRoot = SftpFileSystemConfigBuilder.getInstance().getUserDirIsRoot(getFileSystemOptions());
> String workingDirectory = getRootName().getPath();
> if (workingDirectory != null && (userDirIsRoot == null || !userDirIsRoot.booleanValue()))
{
>     try {
>         channel.cd(workingDirectory); 
>     } catch (SftpException e) {
>         throw new FileSystemException("vfs.provider.sftp/change-work-directory.error",
workingDirectory);
>     }
> }{code}
> It purposelessly switches to root directory of filesystem. There is a fair use-case that
root directory doesn't have read access.
> *Possible Fix:* It should not switch to root directory, rather it should switch to actual
final directory. This approach would be the safest. E.g. if the needed directory is '/sftp/abc'
then it can switch to that directory in above code, rather than switching to root.
> Please also see related SO question:
> https://stackoverflow.com/questions/48709971/why-apache-vfs-sftp-tries-to-switch-to-root-directory-even-when-not-needed



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