FSInfo#getJarClassPath does not comply with the JAR specification

[David Lloyd]

The bug ID never showed up for this.  Is this not acknowledged as a
bug?  And have you had any more thoughts about the specification's
take on `file` URLs?

On Thu, Oct 17, 2019 at 11:08 AM David Lloyd <david.lloyd at redhat.com> wrote:
>
> How would you account for JDK-8216401 in this case?  Would you say
> that the specification should have been updated to account for the
> implementation?
>
> On Thu, Oct 17, 2019 at 9:34 AM Jonathan Gibbons
> <jonathan.gibbons at oracle.com> wrote:
> >
> > Any changes/exceptions should be done in conjunction with updates to
> > specification.
> >
> > -- Jon
> >
> > On 10/17/19 6:04 AM, David Lloyd wrote:
> > > It seems reasonable to include the special exception for `file:` absolute URLs.
> > >
> > > I did file a bug at bugreport but I haven't yet received a
> > > notification that the bug was created. If I do, I will post the JIRA #
> > > here.
> > >
> > > On Wed, Oct 16, 2019 at 9:33 PM Jaikiran Pai <jai.forums2013 at gmail.com> wrote:
> > >> One of the reasonsI hadn't done anything related to this in my proposed
> > >> change to FSInfo#getJarClassPath patch[1] was because I wasn't sure what
> > >> the actual expected semantics of the Class-Path attribute are.
> > >>
> > >> The jar Manifest documentation (which David pointed to) does state the
> > >> URI is to be relative, but I remember seeing a recent change discussed
> > >> in one of these mailing lists where absolute (file: scheme based) URIs
> > >> were supported. I finally found time to look through the JBS and here's
> > >> that issue https://bugs.openjdk.java.net/browse/JDK-8216401. So I think
> > >> whatever change we do here will then have to allow for absolute URI (for
> > >> file: scheme of local jars too).
> > >>
> > >> [1]
> > >> http://mail.openjdk.java.net/pipermail/compiler-dev/2019-October/013760.html
> > >>
> > >> -Jaikiran
> > >>
> > >> On 14/10/19 10:13 PM, David Lloyd wrote:
> > >>> The JAR specification specifies that the `Class-Path` attribute is a
> > >>> space-separated sequence of relative URLs.  A relative URL is defined
> > >>> ([2], [3]) as a hierarchical URI with no scheme component.
> > >>>
> > >>> Relative URLs resemble file paths.  However they differ in some
> > >>> important ways: for example, a relative URL is URL-encoded, whereas a
> > >>> file path is not, causing problems when dealing with paths that have
> > >>> embedded spaces (among other things).  Relative URLs representing
> > >>> absolute paths on Windows have a form like `/C:/Foo/Bar`, whereas the
> > >>> corresponding file path would be `C:/Foo/Bar` or `C:\Foo\Bar`.
> > >>>
> > >>> Note (since this is a point of frequent confusion) that a relative URL
> > >>> can have an absolute path.
> > >>>
> > >>> AFAIK neither of these cases work correctly when javac interacts with
> > >>> a JAR that contains a `Class-Path` attribute.
> > >>>
> > >>> The current FSInfo code, as noted in the recent thread entitled
> > >>> `FSInfo#getJarClassPath throws an exception not declared in its throws
> > >>> clause`, reads the class path attribute value with code that uses
> > >>> FileSystems.getDefault().getPath(xxx) on each class path element [4].
> > >>>
> > >>> The correct behavior would be to wrap each item in a `java.net.URI`.
> > >>> If the syntax is invalid, report an error or skip the element.  Then
> > >>> determine if the URI is absolute; if it is, report an error or skip
> > >>> the element.  Finally, query the Path API to look up the file by URI
> > >>> using Path.of(uri) or similar, reporting an error or skipping the
> > >>> element if there's a problem.
> > >>>
> > >>> The less-elegant solution would be to manually URL-decode the string,
> > >>> and (on windows) manually check to see if there's a drive letter,
> > >>> removing the leading slash if there is one.  However I would consider
> > >>> this to be more likely to be bug-prone.
> > >>>
> > >>> This problem is the underlying cause of at least one Quarkus bug [5],
> > >>> where the issue was discussed in depth.
> > >>>
> > >>> [1] https://docs.oracle.com/javase/10/docs/specs/jar/jar.html#class-path-attribute
> > >>> [2] RFC 3986 § 4.2 - https://tools.ietf.org/html/rfc3986#section-4.2
> > >>> [3] https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/net/URI.html
> > >>> [4] https://github.com/openjdk/jdk/blob/4ad3d82c76936a8927ed8a505689a3683144ad98/src/jdk.compiler/share/classes/com/sun/tools/javac/file/FSInfo.java#L112
> > >>> [5] https://github.com/quarkusio/quarkus/issues/3592
> > >>>
> > >
>
>
>
> --
> - DML



-- 
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