Date: Tue, 14 May 1996 00:49:04 +0200 (MET DST) From: Ollivier Robert <roberto@keltia.freenix.fr> To: chuckr@Glue.umd.edu (Chuck Robey) Cc: FreeBSD-Ports@FreeBSD.org Subject: Re: dynamic linking Message-ID: <199605132249.AAA12774@keltia.freenix.fr> In-Reply-To: <Pine.OSF.3.91.960513004455.7203B-100000@thurston.eng.umd.edu> from Chuck Robey at "May 13, 96 00:50:13 am"
next in thread | previous in thread | raw e-mail | index | archive | help
It seems that Chuck Robey said:
> takes a file from the command line and dloads it. To use a file I knew
> was in correct format, I used one from libc, but I always get this kind
> of error:
> ./dltests /usr/obj/lib/libc/rmdir.so
> testing file /usr/obj/lib/libc/rmdir.so ... dlopen call returned pointer
> value 0
> dlerror call returns mmap failed for "/usr/obj/lib/libc/rmdir.so" :
> Invalid argument
> OK, below is the code I wrote to test it. Anyone got any idea why it's
> failing?
I believe that the code is not failing.
I think the problem lies in the way you use the .so.
Look at /usr/share/mk/bsd.lib.mk how a shared library is generated:
1st phase
The .so is generated by the compiler and run thru "ld -r -x"
------------------------------------------------------------
.c.so:
${CC} ${PICFLAG} -DPIC ${CFLAGS} -c ${.IMPSRC} -o ${.TARGET}
@${LD} -o ${.TARGET}.tmp -x -r ${.TARGET}
@mv ${.TARGET}.tmp ${.TARGET}
------------------------------------------------------------
2nd phase
The .so are collected altogether, the .so order is generated by
"lorder | tsort" and they are all run thru "ld -Bsharable" to
generate the final .so.M.N.
------------------------------------------------------------
lib${LIB}.so.${SHLIB_MAJOR}.${SHLIB_MINOR}: ${SOBJS}
@${ECHO} building shared ${LIB} library \(version ${SHLIB_MAJOR}.${SHLIB_MINOR}\)
@rm -f lib${LIB}.so.${SHLIB_MAJOR}.${SHLIB_MINOR}
@${LD} -Bshareable -x \
-o lib${LIB}.so.${SHLIB_MAJOR}.${SHLIB_MINOR} \
`lorder ${SOBJS} | tsort` ${LDDESTDIR} ${LDADD}
------------------------------------------------------------
Only the result of "ld -Bsharable" can be opened by dlopen(3). You can't
just take "rmdir.so" and map it.
Try:
ld -Bsharable -o rmdir.so.1.0 /usr/obj/lib/libc/rmdir.so
./dltests rmdir.so.1.0
and see what it does.
--
Ollivier ROBERT -=- The daemon is FREE! -=- roberto@keltia.freenix.fr
FreeBSD keltia.freenix.fr 2.2-CURRENT #2: Fri May 10 21:09:14 MET DST 1996
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199605132249.AAA12774>