This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [hurd,commited] hurd: fix build with -fstack-protector-strong
On Mon, 28 Aug 2017, Samuel Thibault wrote:
> Hello,
>
> Joseph Myers, on lun. 28 août 2017 11:44:56 +0000, wrote:
> > On Sun, 27 Aug 2017, Samuel Thibault wrote:
> > > + * mach/Versions (GLIBC_2.4): Add __stack_chk_fail.
> > > + * hurd/Versions (GLIBC_2.4): Add __stack_chk_fail.
> >
> > These changes look suspicious. debug/Versions already exports
> > __stack_chk_fail from libc at version GLIBC_2.4, so I'd expect those new
> > Versions entries to have no effect
>
> Ok, I had misunderstood the use of the similar versions added above
> (__mach_msg, __mach_msg_overwrite, etc. which are defined by mach
> itself)
Well, I'm not familiar with any Mach-specific/Hurd-specific symbol
versioning issues. But as far as I know the following apply generally to
all ports:
* The contents of a particular public symbol version should be fixed at
the time of the corresponding release (subject to any questions around
ports that were completely broken at the time of the release so the
sources people actually used were something else).
* Only one visible (in a subdirectory used by make) Versions entry for a
given (library, symbol, version) triple should be needed. So just the
debug/Versions entry for __stack_chk_fail at version GLIBC_2.4 in libc.
* If a symbol is added only for internal use between glibc's own
libraries, not for use by external programs or libraries, it should have
version GLIBC_PRIVATE. The contents of GLIBC_PRIVATE *can* change
arbitrarily between releases (although adding symbols in bug fixes on
release branches is still problematic, because of the effects on running
programs when you upgrade a live system and the running program later
tries to load another glibc library, which now expects a new GLIBC_PRIVATE
symbol).
* The *.abilist test baselines can be used to verify that past symbol
versions don't get changed unintentionally. Hurd of course needs such
baselines added, which you could verify against existing binaries of
various different versions to make sure they reflect what the ABI of
different versions was in practice.
--
Joseph S. Myers
joseph@codesourcery.com