1/* Convenience declarations when working with <signal.h>.
2
3 Copyright (C) 2008-2019 Free Software Foundation, Inc.
4
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
9
10 This program 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
13 GNU General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <https://www.gnu.org/licenses/>. */
17
18#ifndef _GL_SIG_HANDLER_H
19#define _GL_SIG_HANDLER_H
20
21#include <signal.h>
22
23#ifndef _GL_INLINE_HEADER_BEGIN
24 #error "Please include config.h first."
25#endif
26_GL_INLINE_HEADER_BEGIN
27#ifndef SIG_HANDLER_INLINE
28# define SIG_HANDLER_INLINE _GL_INLINE
29#endif
30
31/* Convenience type when working with signal handlers. */
32typedef void (*sa_handler_t) (int);
33
34/* Return the handler of a signal, as a sa_handler_t value regardless
35 of its true type. The resulting function can be compared to
36 special values like SIG_IGN but it is not portable to call it. */
37SIG_HANDLER_INLINE sa_handler_t _GL_ATTRIBUTE_PURE
38get_handler (struct sigaction const *a)
39{
40 /* POSIX says that special values like SIG_IGN can only occur when
41 action.sa_flags does not contain SA_SIGINFO. But in Linux 2.4,
42 for example, sa_sigaction and sa_handler are aliases and a signal
43 is ignored if sa_sigaction (after casting) equals SIG_IGN. In
44 this case, this implementation relies on the fact that the two
45 are aliases, and simply returns sa_handler. */
46 return a->sa_handler;
47}
48
49_GL_INLINE_HEADER_END
50
51#endif /* _GL_SIG_HANDLER_H */
52