On 6/8/2010 2:46 AM, Gary V. Vaughan wrote: > [[Adding Libtool List]] > > On 8 Jun 2010, at 08:56, Charles Wilson wrote: >> What happens if libltdl is >> used to load (say) libtiff which has an automatic dependency on libjpeg? >> The initial LoadLibrary from libltdl pulls in libtiff.dll AND >> libjpeg.dll, but only libtiff.dll gets a registered handle in libltdl. >> Suppose then the client app explicitly loads libjpeg.dll via libltdl -- >> does that work ok? > > If it doesn't, then that's a bug. Libltdl is supposed to keep track > of everything it loads,
But the point here is that Bob is advocating that (in the first half of the example above) *libltdl* does NOT explicitly load the libjpeg dependency. However, the Windows *will* load it "behind the scenes" and automatically, when libltdl does a LoadLibrary(libtiff) because libtiff depends on libjpeg. Once Windows has done so, and THEN libltdl attempts to do a LoadLibrary(libjpeg) -- when libjpeg has already been "privately" loaded, unbeknownst to libltdl -- what happens? > and if it gets a request for a handle to a > library it loaded already, it can pull one out of it's internal data > structures without having to call the underlying module loader again. Except that in this proposal, its internal data structures wouldn't know that libjpeg has already been loaded. > More interesting still: I think things might blow up if the .la files > have been removed on a platform that does automatic deplib loading for > runtime linking, say lt_dlopening libpng.dll (which pulls in zlib > through LoadLibrary without libltdl knowing about it), and then the > application tries to lt_dlopen libz.dll. Uhm, isn't this the same scenario I was outlining, with libtiff + libjpeg? > It then depends on whether > the underlying LoadLibrary implementation is smart enough to realise > that it already has a copy of libz in memory and returns a handle to > it without trying to reload another copy first... this would be an > interesting test to have in the next release to see what feedback it > brings. Yes. -- Chuck _______________________________________________ http://lists.gnu.org/mailman/listinfo/libtool
