sigtstp.c

unix高级编程源代码.<<unix高级编程>>

#include	<signal.h>
#include	"ourhdr.h"

#define	BUFFSIZE	1024

static void	sig_tstp(int);

int
main(void)
{
	int		n;
	char	buf[BUFFSIZE];

	/* only catch SIGTSTP if we're running with a job-control shell */
	if (signal(SIGTSTP, SIG_IGN) == SIG_DFL)
		signal(SIGTSTP, sig_tstp);

	while ( (n = read(STDIN_FILENO, buf, BUFFSIZE)) > 0)
		if (write(STDOUT_FILENO, buf, n) != n)
			err_sys("write error");
	if (n < 0)
		err_sys("read error");

	exit(0);
}

static void
sig_tstp(int signo)	/* signal handler for SIGTSTP */
{
	sigset_t	mask;

	/* ... move cursor to lower left corner, reset tty mode ... */

	/* unblock SIGTSTP, since it's blocked while we're handling it */
	sigemptyset(&mask);
	sigaddset(&mask, SIGTSTP);
	sigprocmask(SIG_UNBLOCK, &mask, NULL);

	signal(SIGTSTP, SIG_DFL);	/* reset disposition to default */

	kill(getpid(), SIGTSTP);	/* and send the signal to ourself */

		/* we won't return from the kill until we're continued */

	signal(SIGTSTP, sig_tstp);	/* reestablish signal handler */

	/* ... reset tty mode, redraw screen ... */
	return;
}