/* ====================================================================
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Apache" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * Portions of this software are based upon public domain software
 * originally written at the National Center for Supercomputing Applications,
 * University of Illinois, Urbana-Champaign.
 */

/*
 * ap_slack.c: File descriptor preallocation
 * 
 * 3/21/93 Rob McCool
 * 1995-96 Many changes by the Apache Group
 * 
 */

#include "httpd.h"
#include "http_log.h"

#ifndef NO_SLACK
int ap_slack(int fd, int line)
{
#if !defined(F_DUPFD)
    return fd;
#else
    static int low_warned;
    int new_fd;

#ifdef HIGH_SLACK_LINE
    if (line == AP_SLACK_HIGH && fd < HIGH_SLACK_LINE) {
	new_fd = fcntl(fd, F_DUPFD, HIGH_SLACK_LINE);
	if (new_fd != -1) {
	    close(fd);
	    return new_fd;
	}
    }
#endif
    /* otherwise just assume line == AP_SLACK_LOW */
    if (fd >= LOW_SLACK_LINE) {
	return fd;
    }
    new_fd = fcntl(fd, F_DUPFD, LOW_SLACK_LINE);
    if (new_fd == -1) {
	if (!low_warned) {
	    /* Give them a warning here, because we really can't predict
	     * how libraries and such are going to fail.  If we can't
	     * do this F_DUPFD there's a good chance that apache has too
	     * few descriptors available to it.  Note we don't warn on
	     * the high line, because if it fails we'll eventually try
	     * the low line...
	     */
	    ap_log_error(APLOG_MARK, APLOG_WARNING, NULL,
		        "unable to open a file descriptor above %u, "
			"you may need to increase the number of descriptors",
			LOW_SLACK_LINE);
	    low_warned = 1;
	}
	return fd;
    }
    close(fd);
    return new_fd;
#endif
}
#else
/* need at least one function in the file for some linkers */
void ap_slack_is_not_here(void) {}
#endif /* NO_SLACK */