Re: "Symbol X has different size in shared object" bug reappears

Hrvoje> Martin Buchholz <martin(a)xemacs.org&gt; writes: Hrvoje> [...] Hrvoje> I agree with your view -- in fact, I was the one who bitched about the Hrvoje> problem under Solaris which I used at the time. Hrvoje> However, Steve's technical argument against this method was that Linux Hrvoje> makes use of ld.so.conf to ensure old versions of executables for Hrvoje> libraries that need them. This way a libc5 program "knows" that old Hrvoje> libraries are in a "libc5-compat" directory. If we hardcode the Hrvoje> runtime library path into the executable, we lose that capability, Hrvoje> don't we? Well, the way it *should* work is that the RPATH baked into the executable is searched first, and then, if not all libraries are found, /etc/ld.so.conf is searched, and if not all libraries are found, the hardcoded /usr/lib is searched. Does it really not work like that? It might depend on your version of Linux. ..... Hmmmmm. OK, I actually tried it. On my system (Red Hat Linux 6.0) I experimented and found that it works exactly as I expected it to be: - the RPATH specified via -Wl,-rpath=... was used, _but_ if the shared libraries cannot be found there, the system falls back to /etc/ld.so.conf. The world is (relatively) sane. I feel this basically refutes Steve's previous objections, assuming this behavior to be true of modern Linux systems. ..... ok, to be sure, I just tried it as well on Linux 5.2, which is based on kernel 2.0.36, glibc 2.0. It works there the same way. shell transcript follows: (martin＠lasker) ~/src $ cp /usr/X11R6/lib/libX11.so* tt/. (martin＠lasker) ~/src $ gcc29 lib.c -Wl,-rpath=/home/martin/src/tt -L/usr/X11R6/lib -lX11 (martin＠lasker) ~/src $ ldd -v ./a.out libX11.so.6 => /home/martin/src/tt/libX11.so.6 (0x40014000) libc.so.6 => /lib/libc.so.6 (0x400b7000) /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000) Version information: ./a.out: libc.so.6 (GLIBC_2.0) => /lib/libc.so.6 /home/martin/src/tt/libX11.so.6: libc.so.6 (GLIBC_2.1) => /lib/libc.so.6 libc.so.6 (GLIBC_2.0) => /lib/libc.so.6 /lib/libc.so.6: ld-linux.so.2 (GLIBC_2.1) => /lib/ld-linux.so.2 ld-linux.so.2 (GLIBC_2.0) => /lib/ld-linux.so.2 (martin＠lasker) ~/src $ ls -l tt total 2268 -rwxr-xr-x 1 martin martin 769708 Jan 16 03:58 libX11.so -rwxr-xr-x 1 martin martin 769708 Jan 16 03:58 libX11.so.6 -rwxr-xr-x 1 martin martin 769708 Jan 16 03:58 libX11.so.6.1 (martin＠lasker) ~/src $ ./a.out (martin＠lasker) ~/src $ rm -rf tt (martin＠lasker) ~/src $ ldd -v ./a.out libX11.so.6 => /usr/X11R6/lib/libX11.so.6 (0x4001a000) libc.so.6 => /lib/libc.so.6 (0x400b7000) /lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000) Version information: ./a.out: libc.so.6 (GLIBC_2.0) => /lib/libc.so.6 /usr/X11R6/lib/libX11.so.6: libc.so.6 (GLIBC_2.1) => /lib/libc.so.6 libc.so.6 (GLIBC_2.0) => /lib/libc.so.6 /lib/libc.so.6: ld-linux.so.2 (GLIBC_2.1) => /lib/ld-linux.so.2 ld-linux.so.2 (GLIBC_2.0) => /lib/ld-linux.so.2 (martin＠lasker) ~/src $ ./a.out (martin＠lasker) ~/src $ cat lib.c #include <stdio.h> int main (int argc, char *argv[]) { XOpenDisplay ("hello world\n"); return 0; } (martin＠lasker) ~/src $ cat /etc/ld.so.conf /usr/X11R6/lib /usr/lib /usr/i486-linux-libc5/lib