RFR: 7134701 [macosx] Support legacy native library names

[Alan Bateman]

On 28/03/2012 10:52, Michael McMahon wrote:
>
> Maybe, we should be doing what Dan Daugherty suggested yesterday and 
> re-mapping the native
> filename in the case where a full absolute path is passed in (which is 
> the code-path
> when System.load() is called above)
>
> My reasoning (for rejecting that) was that an absolute path is a 
> request for an explicit name
> eg. System.load("/abs/path/libfoo.dylib") and it seems odd to go 
> modifying the path that
> the user provided (as opposed to the System.loadLibrary("foo") case, 
> where we have to
> construct the path internally). But, I hadn't considered the case 
> above where the path
> is constructed by calling System.mapLibraryName().
>
> So, I think a better approach might be to just to check for the old 
> ".jnilib" suffix in all
> the cases, rather than changing System.mapLibraryName(). Otherwise, 
> we'll have an inconsistency
> forever more between the output of that method and the library suffix 
> that we want people
> to use.
>
> I've attached the jdk8 diffs for doing this.
>
> - Michael
I checked Apple's JDK6 and it looks to me that they always favor .jnilib 
over .dylib. If I compile some native code to two shared libraries, one 
with the .dylib suffix and the other with .jnilib then with Apple's JDK6 
it always seems to load the .jnilib version. If only the .dylib library 
exists then it loads that. Also, as per a previous post, the 
System.mapLibraryName method with Apple's JDK6 seems to favor .jnilib 
too. This makes wonder about the original patches in the bsd-port and 
macosx forest as the comments there suggest that ".jnilib" is legacy 
when it seems to have been the favored suffix in JDK6 at least.

Anyway, for jdk7 & jdk8 it looks like we are making a break from the 
past and supporting .jnilib is just to give developers a chance to 
migrate. In that context Dan's suggestion and your latest patch seems 
reasonable but does lead a few anomalies - for example 
System.loadLibrary with an absolute path might succeed even though the 
library will appear to not exist if tested separately. Also I wonder 
about System.mapLibraryName where someone tests to see if the library 
exists before then invoke System.loadLibrary. My guess is that there 
isn't a perfect solution to this as there will always been anomalies in 
a migration like this.

On the latest webrev then the use of final at L1867 is a bit odd and can 
be removed. For the jdk8 version then the fromClass needs to be Class<?>.

-Alan