posix_signals.c

[詳解]

/*++
/* NAME
/*  posix_signals 3
/* SUMMARY
/*  POSIX signal handling compatibility
/* SYNOPSIS
/*  #include <posix_signals.h>
/*
/*  int sigemptyset(m)
/*  sigset_t *m;
/*
/*  int sigaddset(set, signum)
/*  sigset_t *set;
/*  int signum;
/*
/*  int sigprocmask(how, set, old)
/*  int how;
/*  sigset_t *set;
/*  sigset_t *old;
/*
/*  int sigaction(sig, act, oact)
/*  int sig;
/*  struct sigaction *act;
/*  struct sigaction *oact;
/* DESCRIPTION
/*  These routines emulate the POSIX signal handling interface.
/* AUTHOR(S)
/*  Pieter Schoenmakers
/*  Eindhoven University of Technology
/*  P.O. Box 513
/*  5600 MB Eindhoven
/*  The Netherlands
/*--*/

/* System library. */

#include "sys_defs.h"
#include <signal.h>
#include <errno.h>

/* Utility library.*/

#include "posix_signals.h"

#ifdef MISSING_SIGSET_T

int     sigemptyset(sigset_t *m)
{
    return *m = 0;
}

int     sigaddset(sigset_t *set, int signum)
{
    *set |= sigmask(signum);
    return 0;
}

int     sigprocmask(int how, sigset_t *set, sigset_t *old)
{
    int previous;

    if (how == SIG_BLOCK)
    previous = sigblock(*set);
    else if (how == SIG_SETMASK)
    previous = sigsetmask(*set);
    else if (how == SIG_UNBLOCK) {
    int     m = sigblock(0);

    previous = sigsetmask(m & ~*set);
    } else {
    errno = EINVAL;
    return -1;
    }

    if (old)
    *old = previous;
    return 0;
}

#endif

#ifdef MISSING_SIGACTION

static struct sigaction actions[NSIG] = {};

static int sighandle(int signum)
{
    if (signum == SIGCHLD) {
    /* XXX If the child is just stopped, don't invoke the handler.   */
    }
    actions[signum].sa_handler(signum);
}

int     sigaction(int sig, struct sigaction *act, struct sigaction *oact)
{
    static int initialized = 0;

    if (!initialized) {
    int     i;

    for (i = 0; i < NSIG; i++)
        actions[i].sa_handler = SIG_DFL;
    initialized = 1;
    }
    if (sig <= 0 || sig >= NSIG) {
    errno = EINVAL;
    return -1;
    }
    if (oact)
    *oact = actions[sig];

    {
    struct sigvec mine = {
        sighandle, act->sa_mask,
        act->sa_flags & SA_RESTART ? SV_INTERRUPT : 0
    };

    if (sigvec(sig, &mine, NULL))
        return -1;
    }

    actions[sig] = *act;
    return 0;
}

#endif