sortix--sortix/libc/signal/sigismember.cpp

/*******************************************************************************

    Copyright(C) Jonas 'Sortie' Termansen 2013, 2014.

    This file is part of the Sortix C Library.

    The Sortix 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 3 of the License, or (at your
    option) any later version.

    The Sortix 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 Sortix C Library. If not, see <http://www.gnu.org/licenses/>.

    signal/sigismember.cpp
    Test signal membership in a signal set.

*******************************************************************************/

#include <errno.h>
#include <signal.h>
#include <stdint.h>

extern "C" int sigismember(const sigset_t* set, int signum)
{
	int max_signals = sizeof(set->__val) * 8;
	if ( signum < 0 || max_signals <= signum )
		return errno = EINVAL, -1;
	size_t which_byte = signum / 8;
	size_t which_bit  = signum % 8;
	const uint8_t* bytes = (const uint8_t*) set->__val;
	return bytes[which_byte] & (1 << which_bit) ? 1 : 0;
}