FSInfo#getJarClassPath does not comply with the JAR specification

[Jaikiran Pai]

Hello David,

On 23/10/19 7:37 PM, David Lloyd wrote:
> The bug ID never showed up for this. 

Given that there seems to be an acknowledgment, in this thread, that
this current behaviour needs review, I took the liberty to file a bug in
JBS https://bugs.openjdk.java.net/browse/JDK-8232925

-Jaikiran


>  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
>
>