Date: Fri, 21 Apr 2006 11:02:17 +0300 From: Kostik Belousov <kostikbel@gmail.com> To: Jeremie Le Hen <jeremie@le-hen.org> Cc: freebsd-hackers@freebsd.org Subject: Re: [fbsd] Re: Symbol weirdness with static linking Message-ID: <20060421080216.GB1446@deviant.kiev.zoral.com.ua> In-Reply-To: <20060420221623.GD68951@obiwan.tataz.chchile.org> References: <20060420114822.GB35261@obiwan.tataz.chchile.org> <20060420124829.GA1446@deviant.kiev.zoral.com.ua> <20060420221623.GD68951@obiwan.tataz.chchile.org>
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--NMuMz9nt05w80d4+ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Apr 21, 2006 at 12:16:23AM +0200, Jeremie Le Hen wrote: > Hi, Kostik, >=20 > > > For the sake of completeness, I added the output of some objdump(1) > > > outputs here : > > >=20 > > > /usr/obj/usr/src/bin/echo/echo.o: > > > http://tataz.chchile.org/~tataz/symbol_weirdness/objdump-t_echo.txt.gz > > >=20 > > > /usr/obj/usr/src/tmp/usr/lib/libc.a: > > > http://tataz.chchile.org/~tataz/symbol_weirdness/objdump-t_libc.txt.gz > > >=20 > > > /usr/obj/usr/src/tmp/usr/lib/libssp.a: > > > http://tataz.chchile.org/~tataz/symbol_weirdness/objdump-t_libssp.txt= .gz > >=20 > > It seems that you rebuilt world with CFLAGS -fstack-protector, > > since your libc has references to the symbols like __stack_smash_handle= r. > > As result, when linking with sequence -lgcc -lssp -lc -lgcc -lssp, > > and no references from the main object, > > references from libc causes objects from _second_ instance of -lssp to > > be pulled into the link. Since libraries are scanned sequentially, > > this object from libssp has no way to get required dependencies > > from libc. >=20 > Yes, I understand that. But I can't see what's the difference between > "syslog" and "sigfillset" symbols from this standpoint. The fact the > former requires ProPolice/SSP doesn't interfere IMHO. >=20 > > What makes syslog(3) special is that corresponding object from libc, > > syslog.o, requires __stack_smash_handler, while objects for mentioned > > syscalls do not. >=20 > How does it prevent the "syslog" symbol from being found ? Libc > undefined symbols implies the second libssp to be pulled in which in > turn has undefined symbol. But since there is no more libc after this, > "sigfillset" should be missing either. >=20 > I would understand if echo.o needed some symbols provided by the same > archive than "sigfillset" (sigsetops.o) but this is not the case. >=20 You are absolutely right, my error. "Explanation" with syslog dependency on stack_smash is wrong. In fact, building bin/echo on CURRENT with -DNO_SHARED gives deviant% objdump -t echo | grep sigfillset 08056dc0 g F .text 00000021 sigfillset It seems that at least the following dependency chain is present (for 6-STABLE): malloc -> abort -> sigfillset, and malloc is referenced by echo. For CURRENT, (possibly, another) dependency also pulls sig* from libc. Sorry for misinformation, I was innacurate when looking at issue. --NMuMz9nt05w80d4+ Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (FreeBSD) iD8DBQFESJGHC3+MBN1Mb4gRAgJiAJ9gxwu6Yq4CCc5ohDivBMVvWmBFsgCfdi1O 4110x28RkZ6EfhheptEOPCc= =yrs0 -----END PGP SIGNATURE----- --NMuMz9nt05w80d4+--
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