/*
 * Copyright (c) 1992 Eric P. Allman.
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * %sccs.include.redist.c%
 */

#ifndef lint
static char sccsid[] = "@(#)map.c	8.20 (Berkeley) 12/11/93";
#endif /* not lint */

#include "sendmail.h"

#ifdef NDBM
#include <ndbm.h>
#endif
#ifdef NEWDB
#include <db.h>
#endif
#ifdef NIS
#include <rpcsvc/ypclnt.h>
#endif

/*
**  MAP.C -- implementations for various map classes.
**
**	Each map class implements a series of functions:
**
**	bool map_parse(MAP *map, char *args)
**		Parse the arguments from the config file.  Return TRUE
**		if they were ok, FALSE otherwise.  Fill in map with the
**		values.
**
**	char *map_lookup(MAP *map, char *key, char **args, int *pstat)
**		Look up the key in the given map.  If found, do any
**		rewriting the map wants (including "args" if desired)
**		and return the value.  Set *pstat to the appropriate status
**		on error and return NULL.  Args will be NULL if called
**		from the alias routines, although this should probably
**		not be relied upon.  It is suggested you call map_rewrite
**		to return the results -- it takes care of null termination
**		and uses a dynamically expanded buffer as needed.
**
**	void map_store(MAP *map, char *key, char *value)
**		Store the key:value pair in the map.
**
**	bool map_open(MAP *map, int mode)
**		Open the map for the indicated mode.  Mode should
**		be either O_RDONLY or O_RDWR.  Return TRUE if it
**		was opened successfully, FALSE otherwise.  If the open
**		failed an the MF_OPTIONAL flag is not set, it should
**		also print an error.  If the MF_ALIAS bit is set
**		and this map class understands the @:@ convention, it
**		should call aliaswait() before returning.
**
**	void map_close(MAP *map)
**		Close the map.
*/

#define DBMMODE		0644

extern bool	aliaswait __P((MAP *, char *, int));
/*
**  MAP_PARSEARGS -- parse config line arguments for database lookup
**
**	This is a generic version of the map_parse method.
**
**	Parameters:
**		map -- the map being initialized.
**		ap -- a pointer to the args on the config line.
**
**	Returns:
**		TRUE -- if everything parsed OK.
**		FALSE -- otherwise.
**
**	Side Effects:
**		null terminates the filename; stores it in map
*/

bool
map_parseargs(map, ap)
	MAP *map;
	char *ap;
{
	register char *p = ap;

	map->map_mflags |= MF_TRY0NULL | MF_TRY1NULL;
	for (;;)
	{
		while (isascii(*p) && isspace(*p))
			p++;
		if (*p != '-')
			break;
		switch (*++p)
		{
		  case 'N':
			map->map_mflags |= MF_INCLNULL;
			map->map_mflags &= ~MF_TRY0NULL;
			break;

		  case 'O':
			map->map_mflags &= ~MF_TRY1NULL;
			break;

		  case 'o':
			map->map_mflags |= MF_OPTIONAL;
			break;

		  case 'f':
			map->map_mflags |= MF_NOFOLDCASE;
			break;

		  case 'm':
			map->map_mflags |= MF_MATCHONLY;
			break;

		  case 'a':
			map->map_app = ++p;
			break;
		}
		while (*p != '\0' && !(isascii(*p) && isspace(*p)))
			p++;
		if (*p != '\0')
			*p++ = '\0';
	}
	if (map->map_app != NULL)
		map->map_app = newstr(map->map_app);

	if (*p != '\0')
	{
		map->map_file = p;
		while (*p != '\0' && !(isascii(*p) && isspace(*p)))
			p++;
		if (*p != '\0')
			*p++ = '\0';
		map->map_file = newstr(map->map_file);
	}

	while (*p != '\0' && isascii(*p) && isspace(*p))
		p++;
	if (*p != '\0')
		map->map_rebuild = newstr(p);

	if (map->map_file == NULL)
	{
		syserr("No file name for %s map %s",
			map->map_class->map_cname, map->map_mname);
		return FALSE;
	}
	return TRUE;
}
/*
**  MAP_REWRITE -- rewrite a database key, interpolating %n indications.
**
**	It also adds the map_app string.  It can be used as a utility
**	in the map_lookup method.
**
**	Parameters:
**		map -- the map that causes this.
**		s -- the string to rewrite, NOT necessarily null terminated.
**		slen -- the length of s.
**		av -- arguments to interpolate into buf.
**
**	Returns:
**		Pointer to rewritten result.
**
**	Side Effects:
**		none.
*/

struct rwbuf
{
	int	rwb_len;	/* size of buffer */
	char	*rwb_buf;	/* ptr to buffer */
};

struct rwbuf	RwBufs[2];	/* buffers for rewriting output */

char *
map_rewrite(map, s, slen, av)
	register MAP *map;
	register char *s;
	int slen;
	char **av;
{
	register char *bp;
	register char c;
	char **avp;
	register char *ap;
	register struct rwbuf *rwb;
	int i;
	int len;

	if (tTd(39, 1))
	{
		printf("map_rewrite(%.*s), av =", slen, s);
		if (av == NULL)
			printf(" (nullv)");
		else
		{
			for (avp = av; *avp != NULL; avp++)
				printf("\n\t%s", *avp);
		}
		printf("\n");
	}

	rwb = RwBufs;
	if (av == NULL)
		rwb++;

	/* count expected size of output (can safely overestimate) */
	i = len = slen;
	if (av != NULL)
	{
		bp = s;
		for (i = slen; --i >= 0 && (c = *bp++) != 0; )
		{
			if (c != '%')
				continue;
			if (--i < 0)
				break;
			c = *bp++;
			if (!(isascii(c) && isdigit(c)))
				continue;
			for (avp = av; --c >= '0' && *avp != NULL; avp++)
				continue;
			if (*avp == NULL)
				continue;
			len += strlen(*avp);
		}
	}
	if (map->map_app != NULL)
		len += strlen(map->map_app);
	if (rwb->rwb_len < ++len)
	{
		/* need to malloc additional space */
		rwb->rwb_len = len;
		if (rwb->rwb_buf != NULL)
			free(rwb->rwb_buf);
		rwb->rwb_buf = xalloc(rwb->rwb_len);
	}

	bp = rwb->rwb_buf;
	if (av == NULL)
	{
		bcopy(s, bp, slen);
		bp += slen;
	}
	else
	{
		while (--slen >= 0 && (c = *s++) != '\0')
		{
			if (c != '%')
			{
  pushc:
				*bp++ = c;
				continue;
			}
			if (--slen < 0 || (c = *s++) == '\0')
				c = '%';
			if (c == '%')
				goto pushc;
			if (!(isascii(c) && isdigit(c)))
			{
				*bp++ = '%';
				goto pushc;
			}
			for (avp = av; --c >= '0' && *avp != NULL; avp++)
				continue;
			if (*avp == NULL)
				continue;

			/* transliterate argument into output string */
			for (ap = *avp; (c = *ap++) != '\0'; )
				*bp++ = c;
		}
	}
	if (map->map_app != NULL)
		strcpy(bp, map->map_app);
	else
		*bp = '\0';
	if (tTd(39, 1))
		printf("map_rewrite => %s\n", rwb->rwb_buf);
	return rwb->rwb_buf;
}
/*
**  INITMAPS -- initialize for aliasing
**
**	Parameters:
**		rebuild -- if TRUE, this rebuilds the cached versions.
**		e -- current envelope.
**
**	Returns:
**		none.
**
**	Side Effects:
**		initializes aliases:
**		if NDBM:  opens the database.
**		if ~NDBM: reads the aliases into the symbol table.
*/

initmaps(rebuild, e)
	bool rebuild;
	register ENVELOPE *e;
{
	extern void map_init();

#ifdef XDEBUG
	checkfd012("entering initmaps");
#endif
	CurEnv = e;
	if (rebuild)
	{
		stabapply(map_init, 1);
		stabapply(map_init, 2);
	}
	else
	{
		stabapply(map_init, 0);
	}
#ifdef XDEBUG
	checkfd012("exiting initmaps");
#endif
}

void
map_init(s, rebuild)
	register STAB *s;
	int rebuild;
{
	register MAP *map;

	/* has to be a map */
	if (s->s_type != ST_MAP)
		return;

	map = &s->s_map;
	if (!bitset(MF_VALID, map->map_mflags))
		return;

	if (tTd(38, 2))
		printf("map_init(%s:%s, %d)\n",
			map->map_class->map_cname == NULL ? "NULL" :
				map->map_class->map_cname,
			map->map_file == NULL ? "NULL" : map->map_file,
			rebuild);

	if (rebuild == (bitset(MF_ALIAS, map->map_mflags) &&
		    bitset(MCF_REBUILDABLE, map->map_class->map_cflags) ? 1 : 2))
	{
		if (tTd(38, 3))
			printf("\twrong pass\n");
		return;
	}

	/* if already open, close it (for nested open) */
	if (bitset(MF_OPEN, map->map_mflags))
	{
		map->map_class->map_close(map);
		map->map_mflags &= ~(MF_OPEN|MF_WRITABLE);
	}

	if (rebuild == 2)
	{
		rebuildaliases(map, FALSE);
	}
	else
	{
		if (map->map_class->map_open(map, O_RDONLY))
		{
			if (tTd(38, 4))
				printf("\t%s:%s: valid\n",
					map->map_class->map_cname == NULL ? "NULL" :
						map->map_class->map_cname,
					map->map_file == NULL ? "NULL" :
						map->map_file);
			map->map_mflags |= MF_OPEN;
		}
		else if (tTd(38, 4))
			printf("\t%s:%s: invalid: %s\n",
				map->map_class->map_cname == NULL ? "NULL" :
					map->map_class->map_cname,
				map->map_file == NULL ? "NULL" :
					map->map_file,
				errstring(errno));
	}
}
/*
**  NDBM modules
*/

#ifdef NDBM

/*
**  DBM_MAP_OPEN -- DBM-style map open
*/

bool
ndbm_map_open(map, mode)
	MAP *map;
	int mode;
{
	register DBM *dbm;
	struct stat st;

	if (tTd(38, 2))
		printf("ndbm_map_open(%s, %d)\n", map->map_file, mode);

	if (mode == O_RDWR)
		mode |= O_CREAT|O_TRUNC;

	/* open the database */
	dbm = dbm_open(map->map_file, mode, DBMMODE);
	if (dbm == NULL)
	{
#ifdef MAYBENEXTRELEASE
		if (aliaswait(map, ".pag", FALSE))
			return TRUE;
#endif
		if (!bitset(MF_OPTIONAL, map->map_mflags))
			syserr("Cannot open DBM database %s", map->map_file);
		return FALSE;
	}
	map->map_db1 = (void *) dbm;
	if (mode == O_RDONLY)
	{
		if (bitset(MF_ALIAS, map->map_mflags) &&
		    !aliaswait(map, ".pag", TRUE))
			return FALSE;
	}
	else
	{
		int fd;

		/* exclusive lock for duration of rebuild */
		fd = dbm_dirfno((DBM *) map->map_db1);
		if (fd >= 0 && !bitset(MF_LOCKED, map->map_mflags) &&
		    lockfile(fd, map->map_file, ".dir", LOCK_EX))
			map->map_mflags |= MF_LOCKED;
	}
	if (fstat(dbm_dirfno((DBM *) map->map_db1), &st) >= 0)
		map->map_mtime = st.st_mtime;
	return TRUE;
}


/*
**  DBM_MAP_LOOKUP -- look up a datum in a DBM-type map
*/

char *
ndbm_map_lookup(map, name, av, statp)
	MAP *map;
	char *name;
	char **av;
	int *statp;
{
	datum key, val;
	int fd;
	char keybuf[MAXNAME + 1];

	if (tTd(38, 20))
		printf("ndbm_map_lookup(%s)\n", name);

	key.dptr = name;
	key.dsize = strlen(name);
	if (!bitset(MF_NOFOLDCASE, map->map_mflags))
	{
		if (key.dsize > sizeof keybuf - 1)
			key.dsize = sizeof keybuf - 1;
		bcopy(key.dptr, keybuf, key.dsize + 1);
		makelower(keybuf);
		key.dptr = keybuf;
	}
	fd = dbm_dirfno((DBM *) map->map_db1);
	if (fd >= 0 && !bitset(MF_LOCKED, map->map_mflags))
		(void) lockfile(fd, map->map_file, ".dir", LOCK_SH);
	val.dptr = NULL;
	if (bitset(MF_TRY0NULL, map->map_mflags))
	{
		val = dbm_fetch((DBM *) map->map_db1, key);
		if (val.dptr != NULL)
			map->map_mflags &= ~MF_TRY1NULL;
	}
	if (val.dptr == NULL && bitset(MF_TRY1NULL, map->map_mflags))
	{
		key.dsize++;
		val = dbm_fetch((DBM *) map->map_db1, key);
		if (val.dptr != NULL)
			map->map_mflags &= ~MF_TRY0NULL;
	}
	if (fd >= 0 && !bitset(MF_LOCKED, map->map_mflags))
		(void) lockfile(fd, map->map_file, ".dir", LOCK_UN);
	if (val.dptr == NULL)
		return NULL;
	if (bitset(MF_MATCHONLY, map->map_mflags))
		return map_rewrite(map, name, strlen(name), NULL);
	else
		return map_rewrite(map, val.dptr, val.dsize, av);
}


/*
**  DBM_MAP_STORE -- store a datum in the database
*/

void
ndbm_map_store(map, lhs, rhs)
	register MAP *map;
	char *lhs;
	char *rhs;
{
	datum key;
	datum data;
	int stat;

	if (tTd(38, 12))
		printf("ndbm_map_store(%s, %s)\n", lhs, rhs);

	key.dsize = strlen(lhs);
	key.dptr = lhs;

	data.dsize = strlen(rhs);
	data.dptr = rhs;

	if (bitset(MF_INCLNULL, map->map_mflags))
	{
		key.dsize++;
		data.dsize++;
	}

	stat = dbm_store((DBM *) map->map_db1, key, data, DBM_INSERT);
	if (stat > 0)
	{
		usrerr("050 Warning: duplicate alias name %s", lhs);
		stat = dbm_store((DBM *) map->map_db1, key, data, DBM_REPLACE);
	}
	if (stat != 0)
		syserr("readaliases: dbm put (%s)", lhs);
}


/*
**  NDBM_MAP_CLOSE -- close the database
*/

void
ndbm_map_close(map)
	register MAP  *map;
{
	if (bitset(MF_WRITABLE, map->map_mflags))
	{
#ifdef NIS
		bool inclnull;
		char buf[200];

		inclnull = bitset(MF_INCLNULL, map->map_mflags);
		map->map_mflags &= ~MF_INCLNULL;

		(void) sprintf(buf, "%010ld", curtime());
		ndbm_map_store(map, "YP_LAST_MODIFIED", buf);

		(void) gethostname(buf, sizeof buf);
		ndbm_map_store(map, "YP_MASTER_NAME", buf);

		if (inclnull)
			map->map_mflags |= MF_INCLNULL;
#endif

		/* write out the distinguished alias */
		ndbm_map_store(map, "@", "@");
	}
	dbm_close((DBM *) map->map_db1);
}

#endif
/*
**  NEWDB (Hash and BTree) Modules
*/

#ifdef NEWDB

/*
**  BT_MAP_OPEN, HASH_MAP_OPEN -- database open primitives.
**
**	These do rather bizarre locking.  If you can lock on open,
**	do that to avoid the condition of opening a database that
**	is being rebuilt.  If you don't, we'll try to fake it, but
**	there will be a race condition.  If opening for read-only,
**	we immediately release the lock to avoid freezing things up.
**	We really ought to hold the lock, but guarantee that we won't
**	be pokey about it.  That's hard to do.
*/

bool
bt_map_open(map, mode)
	MAP *map;
	int mode;
{
	DB *db;
	int i;
	int omode;
	int fd;
	struct stat st;
	char buf[MAXNAME];

	if (tTd(38, 2))
		printf("bt_map_open(%s, %d)\n", map->map_file, mode);

	omode = mode;
	if (omode == O_RDWR)
	{
		omode |= O_CREAT|O_TRUNC;
#if defined(O_EXLOCK) && defined(HASFLOCK)
		omode |= O_EXLOCK;
# if !defined(OLD_NEWDB)
	}
	else
	{
		omode |= O_SHLOCK;
# endif
#endif
	}

	(void) strcpy(buf, map->map_file);
	i = strlen(buf);
	if (i < 3 || strcmp(&buf[i - 3], ".db") != 0)
		(void) strcat(buf, ".db");
	db = dbopen(buf, omode, DBMMODE, DB_BTREE, NULL);
	if (db == NULL)
	{
#ifdef MAYBENEXTRELEASE
		if (aliaswait(map, ".db", FALSE))
			return TRUE;
#endif
		if (!bitset(MF_OPTIONAL, map->map_mflags))
			syserr("Cannot open BTREE database %s", map->map_file);
		return FALSE;
	}
#if !defined(OLD_NEWDB) && defined(HASFLOCK)
	fd = db->fd(db);
# if !defined(O_EXLOCK)
	if (mode == O_RDWR && fd >= 0)
	{
		if (lockfile(fd, map->map_file, ".db", LOCK_EX))
			map->map_mflags |= MF_LOCKED;
	}
# else
	if (mode == O_RDONLY && fd >= 0)
		(void) lockfile(fd, map->map_file, ".db", LOCK_UN);
	else
		map->map_mflags |= MF_LOCKED;
# endif
#endif

	/* try to make sure that at least the database header is on disk */
	if (mode == O_RDWR)
#ifdef OLD_NEWDB
		(void) db->sync(db);
#else
		(void) db->sync(db, 0);

	if (fd >= 0 && fstat(fd, &st) >= 0)
		map->map_mtime = st.st_mtime;
#endif

	map->map_db2 = (void *) db;
	if (mode == O_RDONLY && bitset(MF_ALIAS, map->map_mflags))
		if (!aliaswait(map, ".db", TRUE))
			return FALSE;
	return TRUE;
}


/*
**  HASH_MAP_INIT -- HASH-style map initialization
*/

bool
hash_map_open(map, mode)
	MAP *map;
	int mode;
{
	DB *db;
	int i;
	int omode;
	int fd;
	struct stat st;
	char buf[MAXNAME];

	if (tTd(38, 2))
		printf("hash_map_open(%s, %d)\n", map->map_file, mode);

	omode = mode;
	if (omode == O_RDWR)
	{
		omode |= O_CREAT|O_TRUNC;
#if defined(O_EXLOCK) && defined(HASFLOCK)
		omode |= O_EXLOCK;
# if !defined(OLD_NEWDB)
	}
	else
	{
		omode |= O_SHLOCK;
# endif
#endif
	}

	(void) strcpy(buf, map->map_file);
	i = strlen(buf);
	if (i < 3 || strcmp(&buf[i - 3], ".db") != 0)
		(void) strcat(buf, ".db");
	db = dbopen(buf, omode, DBMMODE, DB_HASH, NULL);
	if (db == NULL)
	{
#ifdef MAYBENEXTRELEASE
		if (aliaswait(map, ".db", FALSE))
			return TRUE;
#endif
		if (!bitset(MF_OPTIONAL, map->map_mflags))
			syserr("Cannot open HASH database %s", map->map_file);
		return FALSE;
	}
#if !defined(OLD_NEWDB) && defined(HASFLOCK)
	fd = db->fd(db);
# if !defined(O_EXLOCK)
	if (mode == O_RDWR && fd >= 0)
	{
		if (lockfile(fd, map->map_file, ".db", LOCK_EX))
			map->map_mflags |= MF_LOCKED;
	}
# else
	if (mode == O_RDONLY && fd >= 0)
		(void) lockfile(fd, map->map_file, ".db", LOCK_UN);
	else
		map->map_mflags |= MF_LOCKED;
# endif
#endif

	/* try to make sure that at least the database header is on disk */
	if (mode == O_RDWR)
#ifdef OLD_NEWDB
		(void) db->sync(db);
#else
		(void) db->sync(db, 0);

	if (fd >= 0 && fstat(fd, &st) >= 0)
		map->map_mtime = st.st_mtime;
#endif

	map->map_db2 = (void *) db;
	if (mode == O_RDONLY && bitset(MF_ALIAS, map->map_mflags))
		if (!aliaswait(map, ".db", TRUE))
			return FALSE;
	return TRUE;
}


/*
**  DB_MAP_LOOKUP -- look up a datum in a BTREE- or HASH-type map
*/

char *
db_map_lookup(map, name, av, statp)
	MAP *map;
	char *name;
	char **av;
	int *statp;
{
	DBT key, val;
	register DB *db = (DB *) map->map_db2;
	int st;
	int saveerrno;
	int fd;
	char keybuf[MAXNAME + 1];

	if (tTd(38, 20))
		printf("db_map_lookup(%s)\n", name);

	key.size = strlen(name);
	if (key.size > sizeof keybuf - 1)
		key.size = sizeof keybuf - 1;
	key.data = keybuf;
	bcopy(name, keybuf, key.size + 1);
	if (!bitset(MF_NOFOLDCASE, map->map_mflags))
		makelower(keybuf);
#ifndef OLD_NEWDB
	fd = db->fd(db);
	if (fd >= 0 && !bitset(MF_LOCKED, map->map_mflags))
		(void) lockfile(db->fd(db), map->map_file, ".db", LOCK_SH);
#endif
	st = 1;
	if (bitset(MF_TRY0NULL, map->map_mflags))
	{
		st = db->get(db, &key, &val, 0);
		if (st == 0)
			map->map_mflags &= ~MF_TRY1NULL;
	}
	if (st != 0 && bitset(MF_TRY1NULL, map->map_mflags))
	{
		key.size++;
		st = db->get(db, &key, &val, 0);
		if (st == 0)
			map->map_mflags &= ~MF_TRY0NULL;
	}
	saveerrno = errno;
#ifndef OLD_NEWDB
	if (fd >= 0 && !bitset(MF_LOCKED, map->map_mflags))
		(void) lockfile(fd, map->map_file, ".db", LOCK_UN);
#endif
	if (st != 0)
	{
		errno = saveerrno;
		if (st < 0)
			syserr("db_map_lookup: get (%s)", name);
		return NULL;
	}
	if (bitset(MF_MATCHONLY, map->map_mflags))
		return map_rewrite(map, name, strlen(name), NULL);
	else
		return map_rewrite(map, val.data, val.size, av);
}


/*
**  DB_MAP_STORE -- store a datum in the NEWDB database
*/

void
db_map_store(map, lhs, rhs)
	register MAP *map;
	char *lhs;
	char *rhs;
{
	int stat;
	DBT key;
	DBT data;
	register DB *db = map->map_db2;

	if (tTd(38, 20))
		printf("db_map_store(%s, %s)\n", lhs, rhs);

	key.size = strlen(lhs);
	key.data = lhs;

	data.size = strlen(rhs);
	data.data = rhs;

	if (bitset(MF_INCLNULL, map->map_mflags))
	{
		key.size++;
		data.size++;
	}

	stat = db->put(db, &key, &data, R_NOOVERWRITE);
	if (stat > 0)
	{
		usrerr("050 Warning: duplicate alias name %s", lhs);
		stat = db->put(db, &key, &data, 0);
	}
	if (stat != 0)
		syserr("readaliases: db put (%s)", lhs);
}


/*
**  DB_MAP_CLOSE -- add distinguished entries and close the database
*/

void
db_map_close(map)
	MAP *map;
{
	register DB *db = map->map_db2;

	if (tTd(38, 9))
		printf("db_map_close(%s, %x)\n", map->map_file, map->map_mflags);

	if (bitset(MF_WRITABLE, map->map_mflags))
	{
		/* write out the distinguished alias */
		db_map_store(map, "@", "@");
	}

	if (db->close(db) != 0)
		syserr("readaliases: db close failure");
}

#endif
/*
**  NIS Modules
*/

# ifdef NIS

# ifndef YPERR_BUSY
#  define YPERR_BUSY	16
# endif

/*
**  NIS_MAP_OPEN -- open DBM map
*/

bool
nis_map_open(map, mode)
	MAP *map;
	int mode;
{
	int yperr;
	register char *p;
	auto char *vp;
	auto int vsize;
	char *master;

	if (tTd(38, 2))
		printf("nis_map_open(%s)\n", map->map_file);

	if (mode != O_RDONLY)
	{
		/* issue a pseudo-error message */
#ifdef ENOSYS
		errno = ENOSYS;
#else
# ifdef EFTYPE
		errno = EFTYPE;
# else
		errno = ENXIO;
# endif
#endif
		return FALSE;
	}

	p = strchr(map->map_file, '@');
	if (p != NULL)
	{
		*p++ = '\0';
		if (*p != '\0')
			map->map_domain = p;
	}

	if (map->map_domain == NULL)
		yp_get_default_domain(&map->map_domain);

	if (*map->map_file == '\0')
		map->map_file = "mail.aliases";

	/* check to see if this map actually exists */
	yperr = yp_match(map->map_domain, map->map_file, "@", 1,
			&vp, &vsize);
	if (tTd(38, 10))
		printf("nis_map_open: yp_match(%s, %s) => %s\n",
			map->map_domain, map->map_file, yperr_string(yperr));
	if (yperr == 0 || yperr == YPERR_KEY || yperr == YPERR_BUSY)
		return TRUE;

	if (!bitset(MF_OPTIONAL, map->map_mflags))
		syserr("Cannot bind to domain %s: %s", map->map_domain,
			yperr_string(yperr));

	return FALSE;
}


/*
**  NIS_MAP_LOOKUP -- look up a datum in a NIS map
*/

char *
nis_map_lookup(map, name, av, statp)
	MAP *map;
	char *name;
	char **av;
	int *statp;
{
	char *vp;
	auto int vsize;
	int buflen;
	int yperr;
	char keybuf[MAXNAME + 1];

	if (tTd(38, 20))
		printf("nis_map_lookup(%s)\n", name);

	buflen = strlen(name);
	if (buflen > sizeof keybuf - 1)
		buflen = sizeof keybuf - 1;
	bcopy(name, keybuf, buflen + 1);
	if (!bitset(MF_NOFOLDCASE, map->map_mflags))
		makelower(keybuf);
	yperr = YPERR_KEY;
	if (bitset(MF_TRY0NULL, map->map_mflags))
	{
		yperr = yp_match(map->map_domain, map->map_file, keybuf, buflen,
			     &vp, &vsize);
		if (yperr == 0)
			map->map_mflags &= ~MF_TRY1NULL;
	}
	if (yperr == YPERR_KEY && bitset(MF_TRY1NULL, map->map_mflags))
	{
		buflen++;
		yperr = yp_match(map->map_domain, map->map_file, keybuf, buflen,
			     &vp, &vsize);
		if (yperr == 0)
			map->map_mflags &= ~MF_TRY0NULL;
	}
	if (yperr != 0)
	{
		if (yperr != YPERR_KEY && yperr != YPERR_BUSY)
			map->map_mflags &= ~(MF_VALID|MF_OPEN);
		return NULL;
	}
	if (bitset(MF_MATCHONLY, map->map_mflags))
		return map_rewrite(map, name, strlen(name), NULL);
	else
		return map_rewrite(map, vp, vsize, av);
}


/*
**  NIS_MAP_STORE
*/

void
nis_map_store(map, lhs, rhs)
	MAP *map;
	char *lhs;
	char *rhs;
{
	/* nothing */
}


/*
**  NIS_MAP_CLOSE
*/

void
nis_map_close(map)
	MAP *map;
{
	/* nothing */
}

#endif /* NIS */
/*
**  STAB (Symbol Table) Modules
*/


/*
**  STAB_MAP_LOOKUP -- look up alias in symbol table
*/

char *
stab_map_lookup(map, name, av, pstat)
	register MAP *map;
	char *name;
	char **av;
	int *pstat;
{
	register STAB *s;

	if (tTd(38, 20))
		printf("stab_lookup(%s)\n", name);

	s = stab(name, ST_ALIAS, ST_FIND);
	if (s != NULL)
		return (s->s_alias);
	return (NULL);
}


/*
**  STAB_MAP_STORE -- store in symtab (actually using during init, not rebuild)
*/

void
stab_map_store(map, lhs, rhs)
	register MAP *map;
	char *lhs;
	char *rhs;
{
	register STAB *s;

	s = stab(lhs, ST_ALIAS, ST_ENTER);
	s->s_alias = newstr(rhs);
}


/*
**  STAB_MAP_OPEN -- initialize (reads data file)
**
**	This is a wierd case -- it is only intended as a fallback for
**	aliases.  For this reason, opens for write (only during a
**	"newaliases") always fails, and opens for read open the
**	actual underlying text file instead of the database.
*/

bool
stab_map_open(map, mode)
	register MAP *map;
	int mode;
{
	FILE *af;
	struct stat st;

	if (tTd(38, 2))
		printf("stab_map_open(%s)\n", map->map_file);

	if (mode != O_RDONLY)
	{
		errno = ENODEV;
		return FALSE;
	}

	af = fopen(map->map_file, "r");
	if (af == NULL)
		return FALSE;
	readaliases(map, af, TRUE);

	if (fstat(fileno(af), &st) >= 0)
		map->map_mtime = st.st_mtime;
	fclose(af);

	return TRUE;
}


/*
**  STAB_MAP_CLOSE -- close symbol table.
**
**	Since this is in memory, there is nothing to do.
*/

void
stab_map_close(map)
	MAP *map;
{
	/* ignore it */
}
/*
**  Implicit Modules
**
**	Tries several types.  For back compatibility of aliases.
*/


/*
**  IMPL_MAP_LOOKUP -- lookup in best open database
*/

char *
impl_map_lookup(map, name, av, pstat)
	MAP *map;
	char *name;
	char **av;
	int *pstat;
{
	if (tTd(38, 20))
		printf("impl_map_lookup(%s)\n", name);

#ifdef NEWDB
	if (bitset(MF_IMPL_HASH, map->map_mflags))
		return db_map_lookup(map, name, av, pstat);
#endif
#ifdef NDBM
	if (bitset(MF_IMPL_NDBM, map->map_mflags))
		return ndbm_map_lookup(map, name, av, pstat);
#endif
	return stab_map_lookup(map, name, av, pstat);
}

/*
**  IMPL_MAP_STORE -- store in open databases
*/

void
impl_map_store(map, lhs, rhs)
	MAP *map;
	char *lhs;
	char *rhs;
{
#ifdef NEWDB
	if (bitset(MF_IMPL_HASH, map->map_mflags))
		db_map_store(map, lhs, rhs);
#endif
#ifdef NDBM
	if (bitset(MF_IMPL_NDBM, map->map_mflags))
		ndbm_map_store(map, lhs, rhs);
#endif
	stab_map_store(map, lhs, rhs);
}

/*
**  IMPL_MAP_OPEN -- implicit database open
*/

bool
impl_map_open(map, mode)
	MAP *map;
	int mode;
{
	struct stat stb;

	if (tTd(38, 2))
		printf("impl_map_open(%s, %d)\n", map->map_file, mode);

	if (stat(map->map_file, &stb) < 0)
	{
		/* no alias file at all */
		if (tTd(38, 3))
			printf("no map file\n");
		return FALSE;
	}

#ifdef NEWDB
	map->map_mflags |= MF_IMPL_HASH;
	if (hash_map_open(map, mode))
	{
#if defined(NDBM) && defined(NIS)
		if (mode == O_RDONLY || access("/var/yp/Makefile", R_OK) != 0)
#endif
			return TRUE;
	}
	else
		map->map_mflags &= ~MF_IMPL_HASH;
#endif
#ifdef NDBM
	map->map_mflags |= MF_IMPL_NDBM;
	if (ndbm_map_open(map, mode))
	{
		return TRUE;
	}
	else
		map->map_mflags &= ~MF_IMPL_NDBM;
#endif

#if defined(NEWDB) || defined(NDBM)
	if (Verbose)
		message("WARNING: cannot open alias database %s", map->map_file);
#else
	if (mode != O_RDONLY)
		usrerr("Cannot rebuild aliases: no database format defined");
#endif

	return stab_map_open(map, mode);
}


/*
**  IMPL_MAP_CLOSE -- close any open database(s)
*/

void
impl_map_close(map)
	MAP *map;
{
#ifdef NEWDB
	if (bitset(MF_IMPL_HASH, map->map_mflags))
	{
		db_map_close(map);
		map->map_mflags &= ~MF_IMPL_HASH;
	}
#endif

#ifdef NDBM
	if (bitset(MF_IMPL_NDBM, map->map_mflags))
	{
		ndbm_map_close(map);
		map->map_mflags &= ~MF_IMPL_NDBM;
	}
#endif
}
/*
**  NULL stubs
*/

bool
null_map_open(map, mode)
	MAP *map;
	int mode;
{
	return TRUE;
}

void
null_map_close(map)
	MAP *map;
{
	return;
}

void
null_map_store(map, key, val)
	MAP *map;
	char *key;
	char *val;
{
	return;
}