[ipv6] Regarding 8220673: Add test library support for determining platform IP support

[Chris Hegarty]

Arthur,

On 07/05/2019 19:35, Arthur Eubanks wrote:
> ...
> 
> 
> With help from Chris's references ([1]), I added a test with a policy 
> file that grants IPSupport permission to listen/resolve localhost:0, and 
> read the java.net.preferIPv4Stack system property. Without either 
> permission, the test fails as expected.
> One thing I discovered is that to make the policy file work properly 
> with the jtreg directory structure, I needed to add "@build 
> jdk.test.lib.net.IPSupport" to the test. So any test that wants to use 
> IPSupport and security managers needs to have that extra line and make 
> sure that its policy file contains all the permissions as in the new 
> test policy I added.

That is ok.

> Without "@build jdk.test.lib.net.IPSupport", the policy file would need 
> grant codeBase "file:${test.classes}/-"
> With "@build jdk.test.lib.net.IPSupport", the policy file needs grant 
> codeBase "file:${test.classes}/../../../../test/lib/-"

Right, the difference comes from how jtreg builds its dependencies. The
former is an example of when a library is used conveniently with just
the @library tag, the library is automatically compiled into the
specific test's classes directory. The latter is when the library is
explicitly compiled with an @build, and gets put into a shared library
output directory, so that other tests ( that also specify an @build with
that library name ) can use the pre-built classes.

> This matches [1], and seems more restrictive (only applies to test 
> library code) and better.
> 
> New webrev: http://cr.openjdk.java.net/~aeubanks/8220673/webrev.03/

I am happy with this latest version. Reviewed.

Trivially, maybe rename B8220673.java to something more descriptive
( without the bug no. ). Maybe MinimumPermissions? or whatever,
no need for a new webrev.

-Chris.

P.S. adding nio-dev since there are a few tests in that area
being updated.

> 
> [1]: 
> https://hg.openjdk.java.net/jdk/jdk/file/1dc9bf9d016b/test/jdk/java/net/httpclient/AsFileDownloadTest.policy#l24