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-rw-r--r--libpthread/nptl/pthread_join.c106
1 files changed, 106 insertions, 0 deletions
diff --git a/libpthread/nptl/pthread_join.c b/libpthread/nptl/pthread_join.c
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+++ b/libpthread/nptl/pthread_join.c
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+/* Copyright (C) 2002, 2003 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 <stdlib.h>
+
+#include "atomic.h"
+#include "pthreadP.h"
+
+
+static void
+cleanup (void *arg)
+{
+ *(void **) arg = NULL;
+}
+
+
+int
+pthread_join (pthread_t threadid, void **thread_return)
+{
+ struct pthread *self;
+ struct pthread *pd = (struct pthread *) threadid;
+
+ /* Make sure the descriptor is valid. */
+ if (INVALID_NOT_TERMINATED_TD_P (pd))
+ /* Not a valid thread handle. */
+ return ESRCH;
+
+ /* Is the thread joinable?. */
+ if (IS_DETACHED (pd))
+ /* We cannot wait for the thread. */
+ return EINVAL;
+
+ self = THREAD_SELF;
+ if (pd == self
+ || (self->joinid == pd
+ && (pd->cancelhandling
+ & (CANCELING_BITMASK | CANCELED_BITMASK | EXITING_BITMASK
+ | TERMINATED_BITMASK)) == 0))
+ /* This is a deadlock situation. The threads are waiting for each
+ other to finish. Note that this is a "may" error. To be 100%
+ sure we catch this error we would have to lock the data
+ structures but it is not necessary. In the unlikely case that
+ two threads are really caught in this situation they will
+ deadlock. It is the programmer's problem to figure this
+ out. */
+ return EDEADLK;
+
+ /* Wait for the thread to finish. If it is already locked something
+ is wrong. There can only be one waiter. */
+ if (__builtin_expect (atomic_compare_and_exchange_bool_acq (&pd->joinid,
+ self,
+ NULL), 0))
+ /* There is already somebody waiting for the thread. */
+ return EINVAL;
+
+
+ /* During the wait we change to asynchronous cancellation. If we
+ are cancelled the thread we are waiting for must be marked as
+ un-wait-ed for again. */
+ pthread_cleanup_push (cleanup, &pd->joinid);
+
+ /* Switch to asynchronous cancellation. */
+ int oldtype = CANCEL_ASYNC ();
+
+
+ /* Wait for the child. */
+ lll_wait_tid (pd->tid);
+
+
+ /* Restore cancellation mode. */
+ CANCEL_RESET (oldtype);
+
+ /* Remove the handler. */
+ pthread_cleanup_pop (0);
+
+
+ /* We mark the thread as terminated and as joined. */
+ pd->tid = -1;
+
+ /* Store the return value if the caller is interested. */
+ if (thread_return != NULL)
+ *thread_return = pd->result;
+
+
+ /* Free the TCB. */
+ __free_tcb (pd);
+
+ return 0;
+}