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+/* Convenience declarations when working with <signal.h>.
+
+ Copyright (C) 2008-2020 Free Software Foundation, Inc.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+#ifndef _GL_SIG_HANDLER_H
+#define _GL_SIG_HANDLER_H
+
+#include <signal.h>
+
+#ifndef _GL_INLINE_HEADER_BEGIN
+ #error "Please include config.h first."
+#endif
+_GL_INLINE_HEADER_BEGIN
+#ifndef SIG_HANDLER_INLINE
+# define SIG_HANDLER_INLINE _GL_INLINE
+#endif
+
+/* Convenience type when working with signal handlers. */
+typedef void (*sa_handler_t) (int);
+
+/* Return the handler of a signal, as a sa_handler_t value regardless
+ of its true type. The resulting function can be compared to
+ special values like SIG_IGN but it is not portable to call it. */
+SIG_HANDLER_INLINE sa_handler_t _GL_ATTRIBUTE_PURE
+get_handler (struct sigaction const *a)
+{
+ /* POSIX says that special values like SIG_IGN can only occur when
+ action.sa_flags does not contain SA_SIGINFO. But in Linux 2.4,
+ for example, sa_sigaction and sa_handler are aliases and a signal
+ is ignored if sa_sigaction (after casting) equals SIG_IGN. In
+ this case, this implementation relies on the fact that the two
+ are aliases, and simply returns sa_handler. */
+ return a->sa_handler;
+}
+
+_GL_INLINE_HEADER_END
+
+#endif /* _GL_SIG_HANDLER_H */