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testdb.c revision 1.5 
      1 /*	$NetBSD: testdb.c,v 1.5 1997/01/11 06:18:11 mikel Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1992, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #ifndef lint
     37 #if 0
     38 static char sccsid[] = "from: @(#)testdb.c	8.1 (Berkeley) 6/6/93";
     39 #else
     40 static char *rcsid = "$NetBSD: testdb.c,v 1.5 1997/01/11 06:18:11 mikel Exp $";
     41 #endif
     42 #endif /* not lint */
     43 
     44 #include <sys/param.h>
     45 #include <sys/file.h>
     46 #include <errno.h>
     47 #include <limits.h>
     48 #include <kvm.h>
     49 #include <db.h>
     50 #include <stdio.h>
     51 #include <unistd.h>
     52 #include <string.h>
     53 #include <paths.h>
     54 
     55 #include "extern.h"
     56 
     57 /* Return true if the db file is valid, else false */
     58 int
     59 testdb()
     60 {
     61 	register DB *db;
     62 	register int cc, kd, ret, dbversionlen;
     63 	DBT rec;
     64 	struct nlist nitem;
     65 	char dbversion[_POSIX2_LINE_MAX];
     66 	char kversion[_POSIX2_LINE_MAX];
     67 
     68 	ret = 0;
     69 	db = NULL;
     70 
     71 	if ((kd = open(_PATH_KMEM, O_RDONLY, 0)) < 0)
     72 		goto close;
     73 
     74 	if ((db = dbopen(_PATH_KVMDB, O_RDONLY, 0, DB_HASH, NULL)) == NULL)
     75 		goto close;
     76 
     77 	/* Read the version out of the database */
     78 	rec.data = VRS_KEY;
     79 	rec.size = sizeof(VRS_KEY) - 1;
     80 	if ((db->get)(db, &rec, &rec, 0))
     81 		goto close;
     82 	if (rec.data == 0 || rec.size == 0 || rec.size > sizeof(dbversion))
     83 		goto close;
     84 	bcopy(rec.data, dbversion, rec.size);
     85 	dbversionlen = rec.size;
     86 
     87 	/* Read version string from kernel memory */
     88 	rec.data = VRS_SYM;
     89 	rec.size = sizeof(VRS_SYM) - 1;
     90 	if ((db->get)(db, &rec, &rec, 0))
     91 		goto close;
     92 	if (rec.data == 0 || rec.size != sizeof(struct nlist))
     93 		goto close;
     94 	bcopy(rec.data, &nitem, sizeof(nitem));
     95 	/*
     96 	 * Theoretically possible for lseek to be seeking to -1.  Not
     97 	 * that it's something to lie awake nights about, however.
     98 	 */
     99 	errno = 0;
    100 	if (lseek(kd, (off_t)nitem.n_value, SEEK_SET) == -1 && errno != 0)
    101 		goto close;
    102 	cc = read(kd, kversion, sizeof(kversion));
    103 	if (cc < 0 || cc != sizeof(kversion))
    104 		goto close;
    105 
    106 	/* If they match, we win */
    107 	ret = bcmp(dbversion, kversion, dbversionlen) == 0;
    108 
    109 close:	if (kd >= 0)
    110 		(void)close(kd);
    111 	if (db)
    112 		(void)(db->close)(db);
    113 	return (ret);
    114 }
    115