On Thu, 17 Oct 2024 06:09:42 GMT, Alan Bateman <al...@openjdk.org> wrote:
> The JDK supports sym links on Windows and adding support for other unusual
> junctions types has the potential to introduce inconsistencies and weirdness
> that are outside the scope of the APIs.
There appear to be two types of junctions for reparse points with tag
`IO_REPARSE_TAG_MOUNT_POINT`: directory junctions and volume junctions. The
reparse tag is set on a directory which is empty. Both of these reparse points
contain a target string which represents a path.
For directory junctions, the path is an absolute path beginning with a drive
letter such as
C:\Users\username\directory\subdirectory
This path is intended to be to a directory, but there is nothing preventing
storing the path to a file or a symbolic link.
For volume junctions, the path uses a GUID, for example, like this
\?\Volume{blah-foo-bar-gus-blah}\
Presently, the JDK _appears_ already to support "true" directory junctions,
i.e., where the target path begins with a drive letter and is an absolute path
to a directory. The two new tests proposed in this request verify at least a
portion of this behavior. All but two sub-tests of these tests already pass
with no source changes.
> [...] this is not a change that we should rush into.
Agreed. Note that the only actual implementation changes being proposed here are
1. `Files.isSymbolicLink` would return `true` for directory junctions.
2. `Files.readSymbolicLink` would return the target of the mount point.
It is incomplete in the current form of this request, but I think tighter
checks should be performed to ensure that the target does not represent a
volume mount point, nor a regular file, nor a symbolic link.
-------------
PR Comment: https://git.openjdk.org/jdk/pull/21555#issuecomment-2420886803
