Cancellation handling inside libc.

1 files changed, 84 insertions, 0 deletions

diff --git a/nptl/libc-cancellation.c b/nptl/libc-cancellation.c
new file mode 100644
index 0000000..ae568cf
--- /dev/null
+++ b/nptl/libc-cancellation.c
@@ -0,0 +1,84 @@
+/* Copyright (C) 2002 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 <setjmp.h>
+#include <stdlib.h>
+#include "pthreadP.h"
+#include "atomic.h"
+
+
+/* The next two functions are similar to pthread_setcanceltype() but
+   more specialized for the use in the cancelable functions like write().
+   They do not need to check parameters etc.  */
+int
+attribute_hidden
+__libc_enable_asynccancel (void)
+{
+  struct pthread *self = THREAD_SELF;
+  int oldval;
+
+  while (1)
+    {
+      oldval = THREAD_GETMEM (self, cancelhandling);
+      int newval = oldval | CANCELTYPE_BITMASK;
+
+      if (newval == oldval)
+	break;
+
+      if (atomic_compare_and_exchange_acq (&self->cancelhandling, newval,
+					   oldval) == 0)
+	{
+	  if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
+	    {
+	      THREAD_SETMEM (self, result, PTHREAD_CANCELED);
+	      __do_cancel ();
+	    }
+
+	  break;
+	}
+    }
+
+  return oldval;
+}
+
+
+void
+internal_function attribute_hidden
+__libc_disable_asynccancel (int oldtype)
+{
+  /* If asynchronous cancellation was enabled before we do not have
+     anything to do.  */
+  if (oldtype & CANCELTYPE_BITMASK)
+    return;
+
+  struct pthread *self = THREAD_SELF;
+
+  while (1)
+    {
+      int oldval = THREAD_GETMEM (self, cancelhandling);
+      int newval = oldval & ~CANCELTYPE_BITMASK;
+
+      if (newval == oldval)
+	break;
+
+      if (atomic_compare_and_exchange_acq (&self->cancelhandling, newval,
+					   oldval) == 0)
+	break;
+    }
+}