support: Add support_set_small_thread_stack_size

And support_small_stack_thread_attribute

Change-Id: I1cf79a469984f8f30a4a947ee9ec2a5e74de8926

support/support_small_stack_thread_attribute.c

@@ -0,0 +1,54 @@
+/* A thread attribute with a small stack.
+   Copyright (C) 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
+   <https://www.gnu.org/licenses/>.  */
+
+#include <support/xthread.h>
+#include <allocate_once.h>
+
+static void *
+allocate (void *closure)
+{
+  pthread_attr_t *result = malloc (sizeof (*result));
+  xpthread_attr_init (result);
+  support_set_small_thread_stack_size (result);
+  return result;
+}
+
+static void
+deallocate (void *ptr, void *closure)
+{
+  xpthread_attr_destroy (ptr);
+  free (ptr);
+}
+
+static void *small_stack_attr;
+
+pthread_attr_t *
+support_small_stack_thread_attribute (void)
+{
+  return allocate_once (&small_stack_attr, allocate, deallocate, NULL);
+}
+
+static void __attribute__ ((destructor))
+fini (void)
+{
+  if (small_stack_attr != NULL)
+    {
+      deallocate (small_stack_attr, NULL);
+      small_stack_attr = NULL;
+    }
+}