signal.c

unix环境高级编程的源代码

/* 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);
}