[foreign] RFR 8211060: Library.getDefault() does not work on Windows
maurizio.cimadamore at oracle.com
Mon Sep 24 11:10:07 UTC 2018
thanks for the patch. As mentioned last time we have two options here:
one is to follow the approach forward in your patch; another would be to
ditch Library.getDefault() entirely and adopt a more explicit approach -
that is to always require 'implicit' libraries to be mentioned - either
by jextract artifacts or by API points.
A note on the latter - when you do:
the code lookup the @NativeHeader annotation on Foo.class and tries to
extract required library names from there. Currently, we do not add
library names for standard libraries such as "c" or "m" (math), which is
what led us down the (slippery?) slope of having a Library.getDefault
Another option would be to have jextract to always generate the names of
the libraries an artifact depends on, and then the API should throw an
exception if a @NativeHeader is found with no libraries. More
specifically, jextract should always add "c" to the set of used
libraries in the @NativeHeader annotation (other libraries can be
explicitly supplied using the -l flag).
Note that I'm not saying "the binder should always add in 'clib'" for
you, because that's kind of a lame assumption: it works obviously well
for C but it doesn't make a lot of sense if you want to use Panama for
other purposes/languages. Which seems to suggest that, as far as the
binder is concerned, library dependencies should always be explicit.
On 24/09/18 11:52, Jorn Vernee wrote:
> I'd like to contribute a patch that adds support for the default
> library on windows.
> Bug: https://bugs.openjdk.java.net/browse/JDK-8211060
> Diff: https://gist.github.com/JornVernee/7d45780df082cbfb27417b437c7b13a8
> As mentioned before , this fixes 2 bugs:
> 1.) When no library was loaded ClassLoader#NativeLibrary#getFromClass
> threw an NPE (at least on windows). That is fixed by returning
> defaultLibrary.fromClass when the nativeLibraryContext is empty.
> 2.) The default library search was not working on windows. It was using
> a default handle, which works on unix (dlsym(RTLD_DEFAULT)), but not on
> windows (see https://stackoverflow.com/q/23437007). I have changed the
> implementation from using a default handle to using a new native
> function findEntryInProcess, which does the right thing for Windows
> (iterate over all loaded modules), and does the same thing it used to
> for unix. findEntry is now a Java method, and the original findEntry is
> renamed to findEntry0. The NativeLibrary implementation of findEntry
> forwards to findEntry0, and the anonymous class of the default library
> overrides to forward to findEntryInProcess.
> Please test this patch on unix as well, since I don't have the ability
> to do so.
>  :
More information about the panama-dev