dsignal.c   [plain text]

/* -*- c-file-style: "java"; indent-tabs-mode: nil; -*-
 * 
 * distcc -- A simple distributed compiler system
 *
 * Copyright (C) 2002, 2003 by Martin Pool <mbp@samba.org>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program 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
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 */

                /* 
                 * A servant will not be corrected by words: for
                 * though he understand he will not answer.
                 *      -- Proverbs 29:19
                 */

/**
 * @file
 * @brief Daemon signal handling.
 *
 * Signals are handled differently in the daemon parent and its children.
 *
 * When the parent is killed, the entire process group is shut down, and the
 * pid file (if any) is removed.
 *
 * For both cases any temporary files created by the process are removed.
 **/

#include "config.h"

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <signal.h>

#include <sys/types.h>
#include <sys/wait.h>
#include <sys/socket.h>

#include "exitcode.h"
#include "distcc.h"
#include "trace.h"
#include "util.h"
#include "dopt.h"
#include "exec.h"
#include "daemon.h"


/* This stores the pid of the parent daemon.  It's used to make sure
 * that we only run the whole-group cleanup from inside the parent.
 * Remains 0 before parent initialization is complete and when run
 * from inetd. */
volatile pid_t dcc_master_pid = 0;

static RETSIGTYPE dcc_daemon_terminate(int);

/**
 * Catch all relevant termination signals.  Set up in parent and also
 * applies to children.
 **/
void dcc_daemon_catch_signals(void)
{
    /* SIGALRM is caught to allow for built-in timeouts when running test
     * cases. */
 
    signal(SIGTERM, &dcc_daemon_terminate);
    signal(SIGINT, &dcc_daemon_terminate);
    signal(SIGHUP, &dcc_daemon_terminate);
    signal(SIGALRM, &dcc_daemon_terminate);
}



/**
 * Ignore hangup signal.
 *
 * This is only used in detached mode to make sure the daemon does not
 * quit when whoever started it closes their terminal.  In nondetached
 * mode, the signal is logged and causes an exit as normal.
 **/
void dcc_ignore_sighup(void)
{
    signal(SIGHUP, SIG_IGN);

    rs_trace("ignoring SIGHUP");
}



/**
 * Just log, remove pidfile, and exit.
 *
 * Called when a daemon gets a fatal signal.
 *
 * Some cleanup is done only if we're the master/parent daemon.
 **/
static RETSIGTYPE dcc_daemon_terminate(int whichsig)
{
    int am_parent;

    /* Make sure to remove handler before re-raising signal */
    signal(whichsig, SIG_DFL);

    am_parent = getpid() == dcc_master_pid;

    if (am_parent) {
#ifdef HAVE_STRSIGNAL
        rs_log_info("%s", strsignal(whichsig));
#else
        rs_log_info("terminated by signal %d", whichsig);
#endif
    }

    dcc_cleanup_tempfiles();

    if (am_parent) {
        int status;
        pid_t child;
        
        dcc_remove_pid();
        
        do {
            /* kill whole group */
            kill(0, whichsig);
            
            /* reap all children */
            child = waitpid(WAIT_ANY, &status, WNOHANG);
            if (child == 0) {
                rs_log_info("waiting for child exit");
                sleep(1);
            }
        } while (!(child == -1 && errno == ECHILD));
    }

    raise(whichsig);
}