* Versions.def: Add GLIBC_2.6 to libpthread.
[glibc.git] / nptl / sysdeps / unix / sysv / linux / sem_trywait.c
blobf500361143828dcee1fcf917becf4fc33f994430
1 /* sem_trywait -- wait on a semaphore. Generic futex-using version.
2 Copyright (C) 2003 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, write to the Free
18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
19 02111-1307 USA. */
21 #include <errno.h>
22 #include <sysdep.h>
23 #include <lowlevellock.h>
24 #include <internaltypes.h>
25 #include <semaphore.h>
27 #include <shlib-compat.h>
30 int
31 __new_sem_trywait (sem_t *sem)
33 int *futex = (int *) sem;
34 int val;
36 if (*futex > 0)
38 val = atomic_decrement_if_positive (futex);
39 if (val > 0)
40 return 0;
43 __set_errno (EAGAIN);
44 return -1;
46 versioned_symbol (libpthread, __new_sem_trywait, sem_trywait, GLIBC_2_1);
47 #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
48 strong_alias (__new_sem_trywait, __old_sem_trywait)
49 compat_symbol (libpthread, __old_sem_trywait, sem_trywait, GLIBC_2_0);
50 #endif