glibc/rt/clock-compat.c
Florian Weimer f289e656ec rt: Turn forwards from librt to libc into compat symbols [BZ #24194]
As the  result of commit 6e6249d0b4
("BZ#14743: Move clock_* symbols from librt to libc."), in glibc 2.17,
clock_gettime, clock_getres, clock_settime, clock_getcpuclockid,
clock_nanosleep were added to libc, and the file rt/clock-compat.c
was added with forwarders to the actual implementations in libc.
These forwarders were wrapped in

#if SHLIB_COMPAT (librt, GLIBC_2_2, GLIBC_2_17)

so that they are not present for newer architectures (such as
powerpc64le) with a 2.17 or later ABI baseline.  But the forwarders
were not marked as compatibility symbols.  As a result, on older
architectures, historic configure checks such as

AC_CHECK_LIB(rt, clock_gettime)

still cause linking against librt, even though this is completely
unnecessary.  It also creates a needless porting hazard because
architectures behave differently when it comes to symbol availability.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
2019-02-08 10:43:17 +01:00

64 lines
2.1 KiB
C

/* ABI compatibility redirects for clock_* symbols in librt.
Copyright (C) 2012-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <shlib-compat.h>
/* The clock_* symbols were originally defined in librt and so
are part of its ABI. As of 2.17, they have moved to libc.
So we supply definitions for librt that just redirect to
their libc counterparts. */
#if SHLIB_COMPAT (librt, GLIBC_2_2, GLIBC_2_17)
#include <time.h>
#if HAVE_IFUNC
# undef INIT_ARCH
# define INIT_ARCH()
# define COMPAT_REDIRECT(name, proto, arglist) libc_ifunc (name, &__##name) \
compat_symbol (librt, name, name, GLIBC_2_2);
#else
# define COMPAT_REDIRECT(name, proto, arglist) \
int \
name proto \
{ \
return __##name arglist; \
} \
compat_symbol (librt, name, name, GLIBC_2_2);
#endif
COMPAT_REDIRECT (clock_getres,
(clockid_t clock_id, struct timespec *res),
(clock_id, res))
COMPAT_REDIRECT (clock_gettime,
(clockid_t clock_id, struct timespec *tp),
(clock_id, tp))
COMPAT_REDIRECT (clock_settime,
(clockid_t clock_id, const struct timespec *tp),
(clock_id, tp))
COMPAT_REDIRECT (clock_getcpuclockid,
(pid_t pid, clockid_t *clock_id),
(pid, clock_id))
COMPAT_REDIRECT (clock_nanosleep,
(clockid_t clock_id, int flags,
const struct timespec *req,
struct timespec *rem),
(clock_id, flags, req, rem))
#endif