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/* Copyright (C) 1998-2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU 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 2.1 of the License, or (at your option) any later version.
The GNU 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 GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#define __need_NULL
#include <stddef.h>
#include <signal.h>
#include <string.h> /* For the real memset prototype. */
#include <sigsetops.h>
/* Set the disposition for SIG. */
__sighandler_t
sigset (int sig, __sighandler_t disp)
{
struct sigaction act;
struct sigaction oact;
sigset_t set;
sigset_t oset;
__sigemptyset (&set);
if (sigaddset (&set, sig) < 0)
return SIG_ERR;
if (disp == SIG_HOLD)
{
/* Add the signal to the current signal mask. */
if (__sigprocmask (SIG_BLOCK, &set, &oset) < 0)
return SIG_ERR;
/* If the signal was already blocked signal this to the caller. */
if (__sigismember (&oset, sig))
return SIG_HOLD;
/* We need to determine whether a specific handler is installed. */
if (__sigaction (sig, NULL, &oact) < 0)
return SIG_ERR;
return oact.sa_handler;
}
else
{
act.sa_handler = disp;
__sigemptyset (&act.sa_mask);
act.sa_flags = 0;
if (__sigaction (sig, &act, &oact) < 0)
return SIG_ERR;
/* Remove the signal from the current signal mask. */
if (__sigprocmask (SIG_UNBLOCK, &set, &oset) < 0)
return SIG_ERR;
/* If the signal was already blocked return SIG_HOLD. */
return __sigismember (&oset, sig) ? SIG_HOLD : oact.sa_handler;
}
}
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