Graham Barr wrote:
> Well I think it is worth an RFC (not that I have time to write one just now)
> If only to suggest some sample implementations. Do other languages do it ?
> If so how ?
Ok, Ok, I'll do a RFC then... :-)
Actually the only thing affected by LD_LIBRARY_PATH is libperl.so, as
modules are loaded in by dlopen() or equivalent, so the full path in
that case is specified in the call to dlopen().
Solaris 7 onwards has a nice linker feature called $ORIGIN. This allows
the location of run-time linker dependencies to be specified relative to
the location of the executable. This is probably best illustrated with
a simple example:
$ pwd
/tmp/app
$ cat bin/main.c
extern void hi();
int main() { hi(); }
$ cat lib/hi.c
#include <stdio.h>
void hi() { printf("hi!\n"); }
$ cc -G -K pic -o lib/libhi.so lib/hi.c
$ cc -Llib -R '$ORIGIN/../lib' bin/main.c -o bin/main -lhi
$ ldd bin/main
libhi.so => /tmp/app/lib/libhi.so
libc.so.1 => /usr/lib/libc.so.1
libdl.so.1 => /usr/lib/libdl.so.1
/usr/platform/SUNW,Ultra-4/lib/libc_psr.so.1
$ bin/main
hi!
$ cd ..
$ mv app somewhere_else
$ ldd somewhere_else/bin/main
libhi.so => /tmp/somewhere_else/lib/libhi.so
libc.so.1 => /usr/lib/libc.so.1
libdl.so.1 => /usr/lib/libdl.so.1
/usr/platform/SUNW,Ultra-4/lib/libc_psr.so.1
$ somewhere_else/bin/main
hi!
Another option for ELF based platforms that lack $ORIGIN (i.e.
everything other than Solaris AFAIK) would be to use the (standard?)
libelf library to write a little application that tweaked the RPATH in
the executable appropriately when perl is installed somewhere else other
than the default location. I think this would be far preferable to the
currently used horrible hacks involving either LD_LIBRARY_PATH or
greping and patching the executable.
--
Alan Burlison
