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https://issues.apache.org/jira/browse/HADOOP-9043?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13583336#comment-13583336
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Chris Nauroth commented on HADOOP-9043:
---------------------------------------
{quote}
To fix this specific problem, we would want to change FileUtil#symlink to
"normalize the slashes". If you take a look at the branch-1-win code, it
already does this so you can just forward port the patch.
{quote}
This code was already ported to branch-trunk-win several months ago:
{code}
public static int symLink(String target, String linkname) throws IOException{
// Run the input paths through Java's File so that they are converted to the
// native OS form
File targetFile = new File(target);
File linkFile = new File(linkname);
{code}
I believe this jira is no longer valid, at least under its current description.
When I filed it, I didn't realize that Windows requires slightly different API
calls for creating a symlink that targets a directory vs. a file. Therefore,
winutils really does need to call {{DirectoryCheck}} to determine the type of
target. As a consequence, winutils differs from Unix ln in that it cannot
create a dangling symlink. (It has no way of knowing whether the caller is
trying to create a "dangling file symlink" or a "dangling directory symlink".)
I believe that both the Java code and the C code are doing the right thing for
us now, without further changes.
The remaining issue is the failure of {{TestLocalFSFileContextSymlink}} on
Windows, which is what prompted me to file this jira initially. We now know
that this is an inevitable platform difference, so let's use
{{Assert.assumeTrue(!Shell.WINDOWS)}} to skip the tests that can't possibly
pass on Windows. If needed, we could also add more tests to cover Windows
behavior, guarded with {{Assert.assumeTrue(Shell.WINDOWS)}}. AFAIK, Hadoop
product code does not actually require the ability to create a dangling
symlink, and the test suite is just trying to cover ln functionality
exhaustively.
I propose that we close this jira as invalid and create a new one to fix the
tests.
> winutils can create unusable symlinks
> -------------------------------------
>
> Key: HADOOP-9043
> URL: https://issues.apache.org/jira/browse/HADOOP-9043
> Project: Hadoop Common
> Issue Type: Bug
> Components: util
> Affects Versions: 1-win, trunk-win
> Reporter: Chris Nauroth
> Assignee: Arpit Agarwal
> Attachments: HADOOP-9043.branch-1-win.patch, HADOOP-9043.trunk.patch
>
>
> In general, the winutils symlink command rejects attempts to create symlinks
> targeting a destination file that does not exist. However, if given a
> symlink destination with forward slashes pointing at a file that does exist,
> then it creates the symlink with the forward slashes, and then attempts to
> open the file through the symlink will fail.
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