cache.h

早期freebsd实现

/*-
 * Copyright (c) 1992 Keith Muller.
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Keith Muller of the University of California, San Diego.
 *
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS 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 REGENTS OR 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.
 *
 *      @(#)cache.h	8.1 (Berkeley) 5/31/93
 */

/*
 * Constants and data structures used to implement group and password file
 * caches. Traditional passwd/group cache routines perform quite poorly with
 * archives. The chances of hitting a valid lookup with an archive is quite a
 * bit worse than with files already resident on the file system. These misses
 * create a MAJOR performance cost. To adress this problem, these routines
 * cache both hits and misses.
 *
 * NOTE:  name lengths must be as large as those stored in ANY PROTOCOL and
 * as stored in the passwd and group files. CACHE SIZES MUST BE PRIME
 */
#define UNMLEN		32	/* >= user name found in any protocol */
#define GNMLEN		32	/* >= group name found in any protocol */
#define UID_SZ		317	/* size of user_name/uid cache */
#define UNM_SZ		317	/* size of user_name/uid cache */
#define GID_SZ		251	/* size of gid cache */
#define GNM_SZ		317	/* size of group name cache */
#define VALID		1	/* entry and name are valid */
#define INVALID		2	/* entry valid, name NOT valid */

/*
 * Node structures used in the user, group, uid, and gid caches.
 */

typedef struct uidc {
	int valid;		/* is this a valid or a miss entry */
	char name[UNMLEN];	/* uid name */
	uid_t uid;		/* cached uid */
} UIDC;

typedef struct gidc {
	int valid;		/* is this a valid or a miss entry */
	char name[GNMLEN];	/* gid name */
	gid_t gid;		/* cached gid */
} GIDC;