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/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1985-2010 AT&T Intellectual Property *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.opensource.org/licenses/cpl1.0.txt *
* (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Glenn Fowler <gsf@research.att.com> *
* David Korn <dgk@research.att.com> *
* Phong Vo <kpv@research.att.com> *
* *
***********************************************************************/
#pragma prototyped
/*
* Glenn Fowler
* AT&T Research
*
* signal critical region support
*/
#include <ast.h>
#include <sig.h>
static struct
{
int sig;
int op;
}
signals[] = /* held inside critical region */
{
SIGINT, SIG_REG_EXEC,
#ifdef SIGPIPE
SIGPIPE, SIG_REG_EXEC,
#endif
#ifdef SIGQUIT
SIGQUIT, SIG_REG_EXEC,
#endif
#ifdef SIGHUP
SIGHUP, SIG_REG_EXEC,
#endif
#if defined(SIGCHLD) && ( !defined(SIGCLD) || SIGCHLD != SIGCLD || _lib_sigprocmask || _lib_sigsetmask )
SIGCHLD, SIG_REG_PROC,
#endif
#ifdef SIGTSTP
SIGTSTP, SIG_REG_TERM,
#endif
#ifdef SIGTTIN
SIGTTIN, SIG_REG_TERM,
#endif
#ifdef SIGTTOU
SIGTTOU, SIG_REG_TERM,
#endif
};
#ifndef SIG_SETMASK
#undef _lib_sigprocmask
#endif
#if !_lib_sigprocmask && !_lib_sigsetmask
static long hold; /* held signal mask */
/*
* hold last signal for later delivery
*/
static void
interrupt(int sig)
{
signal(sig, interrupt);
hold |= sigmask(sig);
}
#endif
/*
* critical signal region handler
*
* op>0 new region according to SIG_REG_*, return region level
* op==0 pop region, return region level
* op<0 return non-zero if any signals held in current region
*
* signals[] held until region popped
*/
int
sigcritical(int op)
{
register int i;
static int region;
static int level;
#if _lib_sigprocmask
static sigset_t mask;
sigset_t nmask;
#else
#if _lib_sigsetmask
static long mask;
#else
static Sig_handler_t handler[elementsof(signals)];
#endif
#endif
if (op > 0)
{
if (!level++)
{
region = op;
if (op & SIG_REG_SET)
level--;
#if _lib_sigprocmask
sigemptyset(&nmask);
for (i = 0; i < elementsof(signals); i++)
if (op & signals[i].op)
sigaddset(&nmask, signals[i].sig);
sigprocmask(SIG_BLOCK, &nmask, &mask);
#else
#if _lib_sigsetmask
mask = 0;
for (i = 0; i < elementsof(signals); i++)
if (op & signals[i].op)
mask |= sigmask(signals[i].sig);
mask = sigblock(mask);
#else
hold = 0;
for (i = 0; i < elementsof(signals); i++)
if ((op & signals[i].op) && (handler[i] = signal(signals[i].sig, interrupt)) == SIG_IGN)
{
signal(signals[i].sig, handler[i]);
hold &= ~sigmask(signals[i].sig);
}
#endif
#endif
}
return level;
}
else if (op < 0)
{
#if _lib_sigprocmask
sigpending(&nmask);
for (i = 0; i < elementsof(signals); i++)
if (region & signals[i].op)
{
if (sigismember(&nmask, signals[i].sig))
return 1;
}
return 0;
#else
#if _lib_sigsetmask
/* no way to get pending signals without installing handler */
return 0;
#else
return hold != 0;
#endif
#endif
}
else
{
/*
* a vfork() may have intervened so we
* allow apparent nesting mismatches
*/
if (--level <= 0)
{
level = 0;
#if _lib_sigprocmask
sigprocmask(SIG_SETMASK, &mask, NiL);
#else
#if _lib_sigsetmask
sigsetmask(mask);
#else
for (i = 0; i < elementsof(signals); i++)
if (region & signals[i].op)
signal(signals[i].sig, handler[i]);
if (hold)
{
for (i = 0; i < elementsof(signals); i++)
if (region & signals[i].op)
{
if (hold & sigmask(signals[i].sig))
kill(getpid(), signals[i].sig);
}
pause();
}
#endif
#endif
}
return level;
}
}
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