/*-
 * Copyright (c) 2005-2006 Ulf Lilleengen.
 * 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.
 */


#include <sys/param.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/time.h>

#include <assert.h>
#include <err.h>
#include <grp.h>
#include <pthread.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "cache.h"
#include "misc.h"

/*
 * 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 address 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 */
#define BLEN		64		/* buffer length */

/*
 * Node structures used in the user, group, uid, and gid caches.
  */
typedef struct uidc {
	char name[UNMLEN];	/* uid name */
	uid_t uid;		/* cached uid */
	int valid;		/* is this a valid or a miss entry */
} UIDC;

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

/*
 * routines that control user, group, uid and gid caches (for the archive
 * member print routine).
 * IMPORTANT:
 * these routines cache BOTH hits and misses, a major performance improvement
 */
static UIDC **uidtb = NULL;	/* uid to name cache */
static GIDC **gidtb = NULL;	/* gid to name cache */
static UIDC **usrtb = NULL;	/* user name to uid cache */
static GIDC **grptb = NULL;	/* group name to gid cache */

static pthread_mutex_t uidtb_lock;
static pthread_mutex_t gidtb_lock;
static pthread_mutex_t usrtb_lock;
static pthread_mutex_t grptb_lock;

static unsigned int	st_hash(const char *, size_t, int);
static int		uidtb_start(void);
static int		gidtb_start(void);
static int		usrtb_start(void);
static int		grptb_start(void);
static void		cache_lock(pthread_mutex_t*);
static void		cache_unlock(pthread_mutex_t*);

/* Hashes a string */
static unsigned int
st_hash(const char *name, size_t len, int tabsz)
{
	unsigned int key = 0;

	while (len--) {
		key += *name++;
		key = (key << 8) | (key >> 24);
	}
	return (key % tabsz);
}

/*
 * uidtb_start
 *	creates an an empty uidtb
 * Return:
 *	0 if ok, -1 otherwise
 */
static int
uidtb_start(void)
{

	if (uidtb != NULL)
		return (0);
	pthread_mutex_init(&uidtb_lock, NULL);
	uidtb = xmalloc(UID_SZ*sizeof(UIDC *));
	return (0);
}

/*
 * gidtb_start
 *	creates an an empty gidtb
 * Return:
 *	0 if ok, -1 otherwise
 */
static int
gidtb_start(void)
{

	if (gidtb != NULL)
		return (0);
	pthread_mutex_init(&gidtb_lock, NULL);
	gidtb = xmalloc(GID_SZ*sizeof(GIDC *));
	return (0);
}

/*
 * usrtb_start
 *	creates an an empty usrtb
 * Return:
 *	0 if ok, -1 otherwise
 */
static int
usrtb_start(void)
{

	if (usrtb != NULL)
		return (0);
	pthread_mutex_init(&usrtb_lock, NULL);
	usrtb = xmalloc(UNM_SZ*sizeof(UIDC *));
	return (0);
}

/*
 * grptb_start
 *	creates an an empty grptb
 * Return:
 *	0 if ok, -1 otherwise
 */
static int
grptb_start(void)
{

	if (grptb != NULL)
		return (0);
	pthread_mutex_init(&grptb_lock, NULL);
	grptb = xmalloc(GNM_SZ*sizeof(GIDC *));
	return (0);
}

/*
 * name_uid()
 *	caches the name (if any) for the uid. If frc set, we always return the
 *	the stored name (if valid or invalid match). We use a simple hash table.
 * Return
 *	Pointer to stored name (or a empty string)
 */
char *
name_uid(uid_t uid)
{
	struct passwd *pw;
	UIDC *ptr;
	char *nam;

	cache_lock(&uidtb_lock);
	if ((uidtb == NULL) && (uidtb_start() < 0))
		goto bad;

	/*
	 * see if we have this uid cached
	 */
	ptr = uidtb[uid % UID_SZ];
	if ((ptr != NULL) && (ptr->valid > 0) && (ptr->uid == uid)) {
		/*
		 * have an entry for this uid
		 */
		if (ptr->valid == VALID) {
			nam = xstrdup(ptr->name);
			cache_unlock(&uidtb_lock);
			return (nam);
		}
		goto bad;
	}

	/*
	 * No entry for this uid, we will add it
	 */
	if (ptr == NULL)
		ptr = uidtb[uid % UID_SZ] = (UIDC *)xmalloc(sizeof(UIDC));
	pw = getpwuid(uid);
	if (pw == NULL) {
		ptr->uid = uid;
		ptr->valid = INVALID;
		goto bad;
	} else {
		/*
		 * there is an entry for this uid in the password file
		 */
		ptr->uid = pw->pw_uid;
		strncpy(ptr->name, pw->pw_name, UNMLEN - 1);
		ptr->name[UNMLEN - 1] = '\0';
		nam = xstrdup(ptr->name);
		ptr->valid = VALID;
	}
	cache_unlock(&uidtb_lock);
	return (nam);
bad: 
	cache_unlock(&uidtb_lock);
	return (NULL);
}

/*
 * name_gid()
 *	caches the name (if any) for the gid. If frc set, we always return the
 *	the stored name (if valid or invalid match). We use a simple hash table.
 * Return
 *	Pointer to stored name (or a empty string)
 */
char *
name_gid(gid_t gid)
{
	struct group *gr;
	GIDC *ptr;
	char *nam;

	cache_lock(&gidtb_lock);
	if ((gidtb == NULL) && (gidtb_start() < 0))
		goto bad;

	/*
	 * see if we have this gid cached
	 */
	ptr = gidtb[gid % GID_SZ];
	if ((ptr != NULL) && (ptr->valid > 0) && (ptr->gid == gid)) {
		/*
		 * have an entry for this gid
		 */
		if (ptr->valid == VALID) {
			nam = xstrdup(ptr->name);
			cache_unlock(&gidtb_lock);
			return (nam);
		}
		goto bad;
	}

	/*
	 * No entry for this gid, we will add it
	 */
	if (ptr == NULL)
		ptr = gidtb[gid % GID_SZ] = (GIDC *)xmalloc(sizeof(GIDC));
	gr = getgrgid(gid);
	if (gr == NULL) {
		ptr->gid = gid;
		ptr->valid = INVALID;
		goto bad;
	} else {
		/*
		 * there is an entry for this group in the group file
		 */
		ptr->gid = gr->gr_gid;
		strncpy(ptr->name, gr->gr_name, GNMLEN - 1);
		ptr->name[GNMLEN - 1] = '\0';
		nam = xstrdup(ptr->name);
		ptr->valid = VALID;
	}
	cache_unlock(&gidtb_lock);
	return (nam);
bad:
	cache_unlock(&gidtb_lock);
	return (NULL);
}

/*
 * uid_name()
 *	caches the uid for a given user name. We use a simple hash table.
 * Return
 *	the uid (if any) for a user name, or a -1 if no match can be found
 */
int
uid_name(char *name, uid_t *uid)
{
	struct passwd *pw;
	UIDC *ptr;
	int namelen;

	/*
	 * return -1 for mangled names
	 */
	if (((namelen = strlen(name)) == 0) || (name[0] == '\0'))
		return (1);
	cache_lock(&usrtb_lock);
	if ((usrtb == NULL) && (usrtb_start() < 0))
		goto bad;

	/*
	 * look up in hash table, if found and valid return the uid,
	 * if found and invalid, return a -1
	 */
	ptr = usrtb[st_hash(name, namelen, UNM_SZ)];
	if ((ptr != NULL) && (ptr->valid > 0) && !strcmp(name, ptr->name)) {
		if (ptr->valid == INVALID)
			goto bad;
		*uid = ptr->uid;
		cache_unlock(&usrtb_lock);
		return (0);
	}

	if (ptr == NULL)
		ptr = usrtb[st_hash(name, namelen, UNM_SZ)] = (UIDC *)xmalloc(sizeof(UIDC));
	/*
	 * no match, look it up, if no match store it as an invalid entry,
	 * or store the matching uid
	 */
	pw = getpwnam(name);
	if (pw == NULL) {
		strncpy(ptr->name, name, UNMLEN - 1);
		ptr->valid = INVALID;
		goto bad;
	} else {
		strncpy(ptr->name, name, UNMLEN - 1);
		ptr->name[UNMLEN - 1] = '\0';
		ptr->valid = VALID;
		*uid = ptr->uid = pw->pw_uid;
	}
	cache_unlock(&usrtb_lock);
	return (0);
bad:
	cache_unlock(&usrtb_lock);
	return (1);
}

/*
 * gid_name()
 *	caches the gid for a given group name. We use a simple hash table.
 * Return
 *	the gid (if any) for a group name, or a -1 if no match can be found
 */
int
gid_name(char *name, gid_t *gid)
{
	struct group *gr;
	GIDC *ptr;
	int namelen;

	/*
	 * return -1 for mangled names
	 */
	if (((namelen = strlen(name)) == 0) || (name[0] == '\0'))
		return (1);
	cache_lock(&grptb_lock);
	if ((grptb == NULL) && (grptb_start() < 0))
		goto bad;

	/*
	 * look up in hash table, if found and valid return the uid,
	 * if found and invalid, return a -1
	 */
	ptr = grptb[st_hash(name, namelen, GID_SZ)];
	if ((ptr != NULL) && (ptr->valid > 0) && !strcmp(name, ptr->name)) {
		if (ptr->valid == INVALID)
			goto bad;
		*gid = ptr->gid;
		return (0);
	}

	if (ptr == NULL)
		ptr = grptb[st_hash(name, namelen, GID_SZ)] = (GIDC *)xmalloc(sizeof(GIDC));
	/*
	 * no match, look it up, if no match store it as an invalid entry,
	 * or store the matching gid
	 */
	gr = getgrnam(name);
	if (gr == NULL) {
		strncpy(ptr->name, name, GNMLEN - 1);
		ptr->valid = INVALID;
		goto bad;
	} else {
		strncpy(ptr->name, name, GNMLEN - 1);
		ptr->name[GNMLEN - 1] = '\0';
		ptr->valid = VALID;
		*gid = ptr->gid = gr->gr_gid;
	}
	cache_unlock(&grptb_lock);
	return (0);
bad:
	cache_unlock(&grptb_lock);
	return (1);
}

/*
 * Inititalizes cache.
 */
void
cache_init(void)
{

	uidtb_start();
	gidtb_start();
	usrtb_start();
	grptb_start();
}

/*
 * Clean up by destroying mutexes.
 */
void
cache_fini(void)
{

	pthread_mutex_destroy(&uidtb_lock);
	pthread_mutex_destroy(&gidtb_lock);
	pthread_mutex_destroy(&usrtb_lock);
	pthread_mutex_destroy(&grptb_lock);
	free(uidtb);
	free(gidtb);
	free(usrtb);
	free(grptb);
}

static void
cache_lock(pthread_mutex_t *lock)
{
	int error;

	error = pthread_mutex_lock(lock);
	assert(!error);
}

static void
cache_unlock(pthread_mutex_t *lock)
{
	int error;

	error = pthread_mutex_unlock(lock);
	assert(!error);
}