On Wed, 2 Jun 2021 17:19:06 GMT, Maurizio Cimadamore <mcimadam...@openjdk.org> wrote:
> This patch overhauls the library loading mechanism used by the Foreign Linker > API. We realized that, while handy, the *default* lookup abstraction > (`LibraryLookup::ofDefault`) was behaving inconsistentlt across platforms. > > This patch replaces `LibraryLookup` with a simpler `SymbolLookup` > abstraction, a functional interface. Crucially, `SymbolLookup` does not > concern with library loading, only symbol lookup. For this reason, two > factories are added: > > * `SymbolLookup::loaderLookup` - which obtains a lookup that can be used to > lookup symbols in libraries loaded by current loader > * `CLinker::systemLookup` - a more stable replacement for the *default* > lookup, which looks for symbols in libc.so (or its equivalent in other > platforms). The contents of this lookup are unspecified. > > Both factories are *restricted*, so they can only be called when > `--enable-native-access` is set. > _Mailing list message from [Chapman Flack](mailto:c...@anastigmatix.net) on > [security-dev](mailto:security-...@mail.openjdk.java.net):_ > > On 06/02/21 13:30, Maurizio Cimadamore wrote: > > > This patch replaces `LibraryLookup` with a simpler `SymbolLookup` > > abstraction, a functional interface. Crucially, `SymbolLookup` does not > > concern with library loading, only symbol lookup. For this reason, two > > factories are added: > > Hi, > > While I am thinking about this, what will be the behavior when the JVM > itself has been dynamically loaded into an embedding application, and > launched with the JNI invocation API? > > Will there be a *Lookup flavor that is able to find any exported symbol > known in the embedding environment the JVM was loaded into? (This is the > sort of condition the Mac OS linker checks when given the -bundle_loader > option.) > > Regards, > Chapman Flack (maintainer of a project that happens to work that way) Hi, at the moment we don't have plans to add such a lookup, but I believe it should be possible to build such a lookup using `dlopen` and the linker API. I have provided an example elsewhere of how easy it easy to build a wrapper lookup around dlopen/dlsym: https://gist.github.com/mcimadamore/0883ea6f4836ae0c1d2a31c48197da1a Perhaps something like that could be useful in the use case you mention? ------------- PR: https://git.openjdk.java.net/jdk/pull/4316
