On Sun, Mar 09, 2014 at 07:25:20PM -0400, Mike Frysinger wrote: > On Sat 08 Mar 2014 22:30:59 Thomas Klausner wrote: > > There is a bug in dlopen(3). The NOTES section claims: > > > > "The symbols RTLD_DEFAULT and RTLD_NEXT are defined by <dlfcn.h> only > > when _GNU_SOURCE was defined before including it." > > > > However, this is not correct. > > > > From dlfcn.h on a "Gentoo Base System release 2.1": > > #ifdef __USE_GNU > > ... > > # define RTLD_NEXT ((void *) -1l) > > ... > > # define RTLD_DEFAULT ((void *) 0) > > ... > > > > You can verify this by compiling the attached program. For me it gives: > > test.c: In function `main': > > test.c:8: error: `RTLD_NEXT' undeclared (first use in this function) > > test.c:8: error: (Each undeclared identifier is reported only once > > test.c:8: error: for each function it appears in.) > > > > It works if I set "__USE_GNU_" instead. > > > > Please also check the "Glibc extensions: dladdr() and dlvsym()" > > section, it also mentions _GNU_SOURCE. > > the man page is correct. you must define _GNU_SOURCE before including any > headers. you must never use the __USE_XXX defines directly. > > see feature_test_macros(7) for details as the dlopen() man page references. Thanks for your reply. Michael Kerrisk already pointed me to that in a private email. However, this makes writing portable code a bit harder. When I know I need the define for this particular header, I can wrap the header in #define __FOO #include foo.h #undef __FOO but here it seems I have to live with whatever side effects __FOO might have on any other headers. Well, you can't fix that, so thanks for the pointer. Thomas -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
