https://sourceware.org/bugzilla/show_bug.cgi?id=16467
--- Comment #7 from Zbigniew Jędrzejewski-Szmek <zbyszek at in dot waw
.pl> ---
> Can you double check if gold generates the working output?
It seemed to be working for me before, in the sense that at least linking
worked without any error report, and the binary linking the symbols in the
equivalent of libb in the example above was running successfully. I didn't
actually test whether the functions can be correctly called. Updated recipe
that I paste below does that. I use versioned symbols for libb.so too. With
out
that, resulting binary segfaults when it is run.
Also, I had to added -fPIC to the compilation of liba.so. Previously I test
ed
with both gcc-4.7 and gcc-4.8, and the old gcc did not complain about missi
ng
-fPIC, the newer one does. The guess the newer one is right.
--------------------------------------------------
==> liba.c <==
const char* sd_get_seats(void) {return "bla bla";}
==> liba.sym <==
LIBSYSTEMD_209 {
global:
sd_get_seats;
};
==> libb.c <==
void new_sd_get_seats(void);
__asm__(".symver new_sd_get_seats,sd_get_seats@LIBSYSTEMD_209");
static void (*resolve_sd_get_seats(void)) (void) {
return new_sd_get_seats;
}
void sd_get_seats(void) __attribute__((ifunc("resolve_sd_get_seats")));
==> libb.sym <==
LIBSYSTEMD_208 {
global:
sd_get_seats;
};
==> test1.c <==
#include <stdio.h>
const char* sd_get_seats(void);
int main(int argc, char **argv) {
printf("%s\n", sd_get_seats());
return 0;
}
$ gcc -shared -o liba.so liba.c -Wl,--version-script=liba.sym -Wl,-fuse-l
d=gold
-fPIC
$ gcc -shared -fPIC libb.c -o libb.so -L. -la -Wl,-fuse-ld=gold
-Wl,--version-script=libb.sym
$ gcc -L. -lb -Wl,-fuse-ld=gold test1.c -o test1
$ LD_LIBRARY_PATH=. ./test1
bla bla
$ LD_LIBRARY_PATH=. ldd ./test1
linux-vdso.so.1 (0x00007fff81963000)
libb.so => ./libb.so (0x00007faf96c52000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007faf96872000)
liba.so => ./liba.so (0x00007faf9686f000)
/lib64/ld-linux-x86-64.so.2 (0x00007faf96c56000)
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