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1 /* Multithreading primitives.
2    Copyright (C) 2005-2012 Free Software Foundation, Inc.
3 
4    This program is free software; you can redistribute it and/or modify
5    it under the terms of the GNU General Public License as published by
6    the Free Software Foundation; either version 3, or (at your option)
7    any later version.
8 
9    This program is distributed in the hope that it will be useful,
10    but WITHOUT ANY WARRANTY; without even the implied warranty of
11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12    GNU General Public License for more details.
13 
14    You should have received a copy of the GNU General Public License
15    along with this program; if not, see <http://www.gnu.org/licenses/>.  */
16 
17 /* Written by Bruno Haible <bruno@clisp.org>, 2005.  */
18 
19 #include <config.h>
20 
21 /* ========================================================================= */
22 
23 #if USE_POSIX_THREADS
24 
25 /* Use the POSIX threads library.  */
26 
27 # include <pthread.h>
28 # include <stdlib.h>
29 
30 # if PTHREAD_IN_USE_DETECTION_HARD
31 
32 /* The function to be executed by a dummy thread.  */
33 static void *
dummy_thread_func(void * arg)34 dummy_thread_func (void *arg)
35 {
36   return arg;
37 }
38 
39 int
glthread_in_use(void)40 glthread_in_use (void)
41 {
42   static int tested;
43   static int result; /* 1: linked with -lpthread, 0: only with libc */
44 
45   if (!tested)
46     {
47       pthread_t thread;
48 
49       if (pthread_create (&thread, NULL, dummy_thread_func, NULL) != 0)
50         /* Thread creation failed.  */
51         result = 0;
52       else
53         {
54           /* Thread creation works.  */
55           void *retval;
56           if (pthread_join (thread, &retval) != 0)
57             abort ();
58           result = 1;
59         }
60       tested = 1;
61     }
62   return result;
63 }
64 
65 # endif
66 
67 #endif
68 
69 /* ========================================================================= */
70 
71 /* This declaration is solely to ensure that after preprocessing
72    this file is never empty.  */
73 typedef int dummy;
74