glibc/nptl/libc-cleanup.c

/* Copyright (C) 2002-2022 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 "pthreadP.h"
#include <tls.h>
#include <libc-lock.h>

void
__libc_cleanup_push_defer (struct _pthread_cleanup_buffer *buffer)
{
  struct pthread *self = THREAD_SELF;

  buffer->__prev = THREAD_GETMEM (self, cleanup);

  int cancelhandling = atomic_load_relaxed (&self->cancelhandling);

  /* Disable asynchronous cancellation for now.  */
  if (__glibc_unlikely (cancelhandling & CANCELTYPE_BITMASK))
    {
      int newval;
      do
	{
	  newval = cancelhandling & ~CANCELTYPE_BITMASK;
	}
      while (!atomic_compare_exchange_weak_acquire (&self->cancelhandling,
						    &cancelhandling,
						    newval));
    }

  buffer->__canceltype = (cancelhandling & CANCELTYPE_BITMASK
			  ? PTHREAD_CANCEL_ASYNCHRONOUS
			  : PTHREAD_CANCEL_DEFERRED);

  THREAD_SETMEM (self, cleanup, buffer);
}
libc_hidden_def (__libc_cleanup_push_defer)

void
__libc_cleanup_pop_restore (struct _pthread_cleanup_buffer *buffer)
{
  struct pthread *self = THREAD_SELF;

  THREAD_SETMEM (self, cleanup, buffer->__prev);

  int cancelhandling = atomic_load_relaxed (&self->cancelhandling);
  if (buffer->__canceltype != PTHREAD_CANCEL_DEFERRED
      && (cancelhandling & CANCELTYPE_BITMASK) == 0)
    {
      int newval;
      do
	{
	  newval = cancelhandling | CANCELTYPE_BITMASK;
	}
      while (!atomic_compare_exchange_weak_acquire (&self->cancelhandling,
						    &cancelhandling, newval));

      if (cancel_enabled_and_canceled (cancelhandling))
	{
	  self->result = PTHREAD_CANCELED;
	  __do_cancel ();
	}
    }
}
libc_hidden_def (__libc_cleanup_pop_restore)