signal.c

APUE(第二版)的随书源代码,与第一版的代码相比增加了一些章节的代码(详见第二版的说明)

/* Reliable version of signal(), using POSIX sigaction().  */

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

Sigfunc *
signal(int signo, Sigfunc *func)
{
	struct sigaction	act, oact;

	act.sa_handler = func;
	sigemptyset(&act.sa_mask);
	act.sa_flags = 0;
	if (signo == SIGALRM) {
#ifdef	SA_INTERRUPT
		act.sa_flags |= SA_INTERRUPT;	/* SunOS */
#endif
	} else {
#ifdef	SA_RESTART
		act.sa_flags |= SA_RESTART;		/* SVR4, 44BSD */
#endif
	}
	if (sigaction(signo, &act, &oact) < 0)
		return(SIG_ERR);
	return(oact.sa_handler);
}