/* sem_wait -- wait on a semaphore.  Generic futex-using version.   Copyright (C) 2003, 2007 Free Software Foundation, Inc.   This file is part of the GNU C Library.   Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.   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, write to the Free   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA   02111-1307 USA.  */#include <errno.h>#include <sysdep.h>#include <lowlevellock.h>#include <internaltypes.h>#include <semaphore.h>#include <pthreadP.h>#include <shlib-compat.h>voidattribute_hidden__sem_wait_cleanup (void *arg){  struct new_sem *isem = (struct new_sem *) arg;  atomic_decrement (&isem->nwaiters);}int__new_sem_wait (sem_t *sem){  struct new_sem *isem = (struct new_sem *) sem;  int err;  if (atomic_decrement_if_positive (&isem->value) > 0)    return 0;  atomic_increment (&isem->nwaiters);  pthread_cleanup_push (__sem_wait_cleanup, isem);  while (1)    {      /* Enable asynchronous cancellation.  Required by the standard.  */      int oldtype = __pthread_enable_asynccancel ();      err = lll_futex_wait (&isem->value, 0,			    isem->private ^ FUTEX_PRIVATE_FLAG);      /* Disable asynchronous cancellation.  */      __pthread_disable_asynccancel (oldtype);      if (err != 0 && err != -EWOULDBLOCK)	{	  __set_errno (-err);	  err = -1;	  break;	}      if (atomic_decrement_if_positive (&isem->value) > 0)	{	  err = 0;	  break;	}    }  pthread_cleanup_pop (0);  atomic_decrement (&isem->nwaiters);  return err;}versioned_symbol (libpthread, __new_sem_wait, sem_wait, GLIBC_2_1);#if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)intattribute_compat_text_section__old_sem_wait (sem_t *sem){  int *futex = (int *) sem;  int err;  do    {      if (atomic_decrement_if_positive (futex) > 0)	return 0;      /* Enable asynchronous cancellation.  Required by the standard.  */      int oldtype = __pthread_enable_asynccancel ();      /* Always assume the semaphore is shared.  */      err = lll_futex_wait (futex, 0, LLL_SHARED);      /* Disable asynchronous cancellation.  */      __pthread_disable_asynccancel (oldtype);    }  while (err == 0 || err == -EWOULDBLOCK);  __set_errno (-err);  return -1;}compat_symbol (libpthread, __old_sem_wait, sem_wait, GLIBC_2_0);#endif