sighold.c

来自「操作系统SunOS 4.1.3版本的源码」· C语言 代码 · 共 100 行

#if !defined(lint) && defined(SCCSIDS)
static char sccsid[] = "@(#)sighold.c 1.1 92/07/30 SMI";
#endif

/*
 * Copyright (c) 1987 Sun Microsystems, Inc. 
 */

#include <errno.h>
#include <sys/signal.h>

int
sighold(sig)
	int sig;
{

	if (sig == SIGKILL) {
		errno = EINVAL;
		return (-1);	/* sigblock quietly disallows SIGKILL */
	}
	(void) sigblock(sigmask(sig));
	return (0);		/* SVID specifies 0 return on success */
}

int
sigrelse(sig)
	int sig;
{

	if (sig == SIGKILL) {
		errno = EINVAL;
		return (-1);	/* sigsetmask quietly disallows SIGKILL */
	}
	(void) sigsetmask(sigblock(0) & ~sigmask(sig));
	return (0);		/* SVID specifies 0 return on success */
}

int
sigignore(sig)
	int sig;
{
	struct sigvec vec;

	if (sig == SIGKILL) {
		errno = EINVAL;
		return (-1);	/* sigsetmask quietly disallows SIGKILL */
	}
	if (sigvec(sig, (struct sigvec *)0, &vec) < 0)
		return (-1);
	vec.sv_handler = SIG_IGN;
	if (sigvec(sig, &vec, (struct sigvec *)0) < 0)
		return (-1);
	(void) sigsetmask(sigblock(0) & ~sigmask(sig));
	return (0);		/* SVID specifies 0 return on success */
}

void (*
sigset(sig, func))()
	int sig;
	void (*func)();
{
	struct sigvec newvec;
	int newmask;
	struct sigvec oldvec;
	int oldmask;

	if (sigvec(sig, (struct sigvec *)0, &oldvec) < 0)
		return (SIG_ERR);
	oldmask = sigblock(0);
	newvec = oldvec;
	newvec.sv_flags |= SV_INTERRUPT;
	newvec.sv_flags &= ~SV_RESETHAND;
	newvec.sv_mask = 0;
	newmask = oldmask;
	if (func == SIG_HOLD) {
		/*
		 * Signal will be held.  Set the bit for that
		 * signal in the signal mask.  Leave the action
		 * alone.
		 */
		newmask |= sigmask(sig);
	} else {
		/*
		 * Signal will not be held.  Clear the bit
		 * for it in the signal mask.  Set the action
		 * for it.
		 */
		newmask &= ~sigmask(sig);
		newvec.sv_handler = func;
	}
	if (sigvec(sig, &newvec, (struct sigvec *)0) < 0)
		return (SIG_ERR);
	if (sigsetmask(newmask) < 0)
		return (SIG_ERR);
	if (oldmask & sigmask(sig))
		return (SIG_HOLD);      /* signal was held */
	else
		return (oldvec.sv_handler);
}