1 /* Swap to new context.
2    Copyright (C) 2008-2021 Free Software Foundation, Inc.
3    This file is part of the GNU C Library.
4 
5    The GNU C Library is free software; you can redistribute it and/or
6    modify it under the terms of the GNU Lesser General Public
7    License as published by the Free Software Foundation; either
8    version 2.1 of the License, or (at your option) any later version.
9 
10    The GNU C Library is distributed in the hope that it will be useful,
11    but WITHOUT ANY WARRANTY; without even the implied warranty of
12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
13    Lesser General Public License for more details.
14 
15    You should have received a copy of the GNU Lesser General Public
16    License along with the GNU C Library.  If not, see
17    <https://www.gnu.org/licenses/>.  */
18 
19 #include <ucontext.h>
20 
21 extern int __getcontext (ucontext_t *ucp);
22 extern int __setcontext (const ucontext_t *ucp);
23 
24 int
__swapcontext(ucontext_t * oucp,const ucontext_t * ucp)25 __swapcontext (ucontext_t *oucp, const ucontext_t *ucp)
26 {
27   /* Save the current machine context to oucp.  */
28   __getcontext (oucp);
29 
30   /* mark sc_sar flag to skip the setcontext call on reactivation.  */
31   if (oucp->uc_mcontext.sc_sar == 0) {
32 	oucp->uc_mcontext.sc_sar++;
33 
34 	/* Restore the machine context in ucp.  */
35 	__setcontext (ucp);
36   }
37 
38   return 0;
39 }
40 
41 weak_alias (__swapcontext, swapcontext)
42