[jira] [Commented] (HADOOP-9819) FileSystem#rename is broken, deletes target when renaming link to itself

["Andras Bokor (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-9819?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15467808#comment-15467808 ] 

Andras Bokor commented on HADOOP-9819:
--------------------------------------

Thanks for looking into it [~cnauroth],

My explanation:

I found the same behavior in {{AbstractFileSystem}}.
{code:title=AbstractFileSystem.java}
if (dst.equals(src)) {
        throw new FileAlreadyExistsException(
            "The source "+src+" and destination "+dst+" are the same");
}
{code}

In addition {{SymlinkBaseTest#testRenameSymlinkToItself}} (which is a general test case for symlinks) relays on the same behavior and it is not overwritten in any test classes.

I run {{TestSymlinkHdfsFileSystem}} which will use {{DistributedFileSystem}}. At the end the rename operation will happen in {{FSDirRenameOp}} class which also throws exception.

{code:title=FSDirRenameOp.java}
if (dst.equals(src)) {
      throw new FileAlreadyExistsException("The source " + src +
          " and destination " + dst + " are the same");
}
{code}

Throwing {{FileAlreadyExistsException}} is consistent with {{SymlinkBaseTest}}.

> FileSystem#rename is broken, deletes target when renaming link to itself
> ------------------------------------------------------------------------
>
>                 Key: HADOOP-9819
>                 URL: https://issues.apache.org/jira/browse/HADOOP-9819
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: fs
>    Affects Versions: 3.0.0-alpha1
>            Reporter: Arpit Agarwal
>            Assignee: Andras Bokor
>         Attachments: HADOOP-9819.01.patch, HADOOP-9819.02.patch, HADOOP-9819.03.patch
>
>
> Uncovered while fixing TestSymlinkLocalFsFileSystem on Windows.
> This block of code deletes the symlink, the correct behavior is to do nothing.
> {code:java}
>     try {
>       dstStatus = getFileLinkStatus(dst);
>     } catch (IOException e) {
>       dstStatus = null;
>     }
>     if (dstStatus != null) {
>       if (srcStatus.isDirectory() != dstStatus.isDirectory()) {
>         throw new IOException("Source " + src + " Destination " + dst
>             + " both should be either file or directory");
>       }
>       if (!overwrite) {
>         throw new FileAlreadyExistsException("rename destination " + dst
>             + " already exists.");
>       }
>       // Delete the destination that is a file or an empty directory
>       if (dstStatus.isDirectory()) {
>         FileStatus[] list = listStatus(dst);
>         if (list != null && list.length != 0) {
>           throw new IOException(
>               "rename cannot overwrite non empty destination directory " + dst);
>         }
>       }
>       delete(dst, false);
> {code}



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