dsignal.c

用来编写 unix 环境下的守护程序的工具库

/* $Id: dsignal.c 117 2007-06-11 15:34:47Z lennart $ */

/*
 * This file is part of libdaemon.
 *
 * libdaemon is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * libdaemon is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with libdaemon; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <stdarg.h>
#include <signal.h>

#include "dsignal.h"
#include "dlog.h"
#include "dnonblock.h"

static int _signal_pipe[2] = { -1, -1 };

static void _sigfunc(int s) {
    write(_signal_pipe[1], &s, sizeof(s));
}

static int _init(void) {

    if (_signal_pipe[0] < 0 || _signal_pipe[1] < 0) {
        if (pipe(_signal_pipe) < 0) {
            daemon_log(LOG_ERR, "pipe(): %s", strerror(errno));
            return -1;
        }

        if (daemon_nonblock(_signal_pipe[0], 1) < 0 || daemon_nonblock(_signal_pipe[1], 1) < 0)
            return -1;
    }

    return 0;
}

int daemon_signal_install(int s){
    sigset_t ss;
    struct sigaction sa;

    if (_init() < 0)
        return -1;
    
    if (sigemptyset(&ss) < 0) {
        daemon_log(LOG_ERR, "sigemptyset(): %s", strerror(errno));
        return -1;
    }

    if (sigaddset(&ss, s) < 0) {
        daemon_log(LOG_ERR, "sigaddset(): %s", strerror(errno));
        return -1;
    }

    if (sigprocmask(SIG_UNBLOCK, &ss, NULL) < 0) {
        daemon_log(LOG_ERR, "sigprocmask(): %s", strerror(errno));
        return -1;
    }

    memset(&sa, 0, sizeof(sa));
    sa.sa_handler = _sigfunc;
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = SA_RESTART;
        
    if (sigaction(s, &sa, NULL) < 0) {
        daemon_log(LOG_ERR, "sigaction(%s, ...) failed: %s", strsignal(s), strerror(errno));
        return -1;
    }

    return 0;
}

int daemon_signal_init(int s, ...) {
    int sig, r = 0;
    
    va_list ap;
    va_start(ap, s);

    if (_init() < 0)
        return -1;

    sig = s;
    while (sig > 0) {
        if (daemon_signal_install(sig) < 0) {
            r = -1;
            break;
        }
        
        sig = va_arg(ap, int);
    }
            
    va_end(ap);
 
    return r;
}

void daemon_signal_done(void) {
    if (_signal_pipe[0] != -1)
        close(_signal_pipe[0]);
    
    if (_signal_pipe[1] != -1)
        close(_signal_pipe[1]);

    _signal_pipe[0] = _signal_pipe[1] = -1;
}

int daemon_signal_next(void) {
    int s;
    ssize_t r;

    if ((r = read(_signal_pipe[0], &s, sizeof(s))) == sizeof(s))
        return s;
    
    if (r < 0) {

        if (errno == EAGAIN)
            return 0;
        else {
            daemon_log(LOG_ERR, "read(signal_pipe[0], ...): %s", strerror(errno));
            return -1;
        }
    }
    
    daemon_log(LOG_ERR, "Short read() on signal pipe.");
    return -1;
}

int daemon_signal_fd(void) {
    return _signal_pipe[0];
}