Clean up error returns for unsupported pthread mutex/cond attr values

nptl/pthread_mutexattr_setpshared.c

 /* Copyright (C) 2002, 2005 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
 
    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 <pthreadP.h>
 
 
 int
 pthread_mutexattr_setpshared (attr, pshared)
      pthread_mutexattr_t *attr;
      int pshared;
 {
-  struct pthread_mutexattr *iattr;
+  switch (pshared)
+    {
+    case PTHREAD_PROCESS_PRIVATE:       /* This is the default state.  */
+      return 0;
 
-  if (pshared != PTHREAD_PROCESS_PRIVATE
-      && __builtin_expect (pshared != PTHREAD_PROCESS_SHARED, 0))
-    return EINVAL;
+    case PTHREAD_PROCESS_SHARED:        /* NaCl does not support this.  */
+      return ENOTSUP;
 
-  iattr = (struct pthread_mutexattr *) attr;
-
-  if (pshared == PTHREAD_PROCESS_PRIVATE)
-    iattr->mutexkind &= ~PTHREAD_MUTEXATTR_FLAG_PSHARED;
-  else
-    iattr->mutexkind |= PTHREAD_MUTEXATTR_FLAG_PSHARED;
-
-  return 0;
+    default:                            /* Anything else is bogus.  */
+      return EINVAL;
+    }
 }