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/* POSIX compatible signal blocking.
Copyright (C) 2006-2007 Free Software Foundation, Inc.
Written by Bruno Haible <bruno@clisp.org>, 2006.
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 2, 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, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
#include <config.h>
/* Specification. */
#include <signal.h>
#include <errno.h>
#include <stdint.h>
#include <stdlib.h>
/* We assume that a platform without POSIX signal blocking functions also
does not have the POSIX sigaction() function, only the signal() function.
This is true for Woe32 platforms. */
/* A signal handler. */
typedef void (*handler_t) (int signal);
int
sigismember (const sigset_t *set, int sig)
{
if (sig >= 0 && sig < NSIG)
return (*set >> sig) & 1;
else
return 0;
}
int
sigemptyset (sigset_t *set)
{
*set = 0;
return 0;
}
int
sigaddset (sigset_t *set, int sig)
{
if (sig >= 0 && sig < NSIG)
{
*set |= 1U << sig;
return 0;
}
else
{
errno = EINVAL;
return -1;
}
}
int
sigdelset (sigset_t *set, int sig)
{
if (sig >= 0 && sig < NSIG)
{
*set &= ~(1U << sig);
return 0;
}
else
{
errno = EINVAL;
return -1;
}
}
int
sigfillset (sigset_t *set)
{
*set = (2U << (NSIG - 1)) - 1;
return 0;
}
/* Set of currently blocked signals. */
static sigset_t blocked_set /* = 0 */;
/* Set of currently blocked and pending signals. */
static volatile sig_atomic_t pending_array[NSIG] /* = { 0 } */;
/* Signal handler that is installed for blocked signals. */
static void
blocked_handler (int sig)
{
if (sig >= 0 && sig < NSIG)
pending_array[sig] = 1;
}
int
sigpending (sigset_t *set)
{
sigset_t pending = 0;
int sig;
for (sig = 0; sig < NSIG; sig++)
if (pending_array[sig])
pending |= 1U << sig;
return pending;
}
/* The previous signal handlers.
Only the array elements corresponding to blocked signals are relevant. */
static handler_t old_handlers[NSIG];
int
sigprocmask (int operation, const sigset_t *set, sigset_t *old_set)
{
if (old_set != NULL)
*old_set = blocked_set;
if (set != NULL)
{
sigset_t new_blocked_set;
sigset_t to_unblock;
sigset_t to_block;
switch (operation)
{
case SIG_BLOCK:
new_blocked_set = blocked_set | *set;
break;
case SIG_SETMASK:
new_blocked_set = *set;
break;
case SIG_UNBLOCK:
new_blocked_set = blocked_set & ~*set;
break;
default:
errno = EINVAL;
return -1;
}
to_unblock = blocked_set & ~new_blocked_set;
to_block = new_blocked_set & ~blocked_set;
if (to_block != 0)
{
int sig;
for (sig = 0; sig < NSIG; sig++)
if ((to_block >> sig) & 1)
{
pending_array[sig] = 0;
if ((old_handlers[sig] = signal (sig, blocked_handler)) != SIG_ERR)
blocked_set |= 1U << sig;
}
}
if (to_unblock != 0)
{
sig_atomic_t received[NSIG];
int sig;
for (sig = 0; sig < NSIG; sig++)
if ((to_unblock >> sig) & 1)
{
if (signal (sig, old_handlers[sig]) != blocked_handler)
/* The application changed a signal handler while the signal
was blocked. We don't support this. */
abort ();
received[sig] = pending_array[sig];
blocked_set &= ~(1U << sig);
pending_array[sig] = 0;
}
else
received[sig] = 0;
for (sig = 0; sig < NSIG; sig++)
if (received[sig])
{
#if HAVE_RAISE
raise (sig);
#else
kill (getpid (), sig);
#endif
}
}
}
return 0;
}
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