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https://issues.apache.org/jira/browse/VFS-651?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16366859#comment-16366859
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Otto Fowler commented on VFS-651:
---------------------------------
Oh, tweaking. Right.
I'm sorry [~aqeel613], I'm not a committer or even a contributor on this
project. I use it on my apache project and saw your mail on the list and was
curious so I thought I would take a look.
As far as I can see it is working as designed. It makes sense to me for a file
system to work like this, but if this where just a sftp client maybe it would
be different.
Maybe someone who participated in the design will be able to explain the
reasons better than what I can say just from going through the code and
documentation.
> 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:myp...@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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