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testdb.c revision 1.1 
      1 /*-
      2  * Copyright (c) 1992, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #ifndef lint
     35 static char sccsid[] = "@(#)testdb.c	8.1 (Berkeley) 6/6/93";
     36 #endif /* not lint */
     37 
     38 #include <sys/param.h>
     39 #include <sys/file.h>
     40 #include <errno.h>
     41 #include <limits.h>
     42 #include <kvm.h>
     43 #include <db.h>
     44 #include <stdio.h>
     45 #include <unistd.h>
     46 #include <string.h>
     47 #include <paths.h>
     48 
     49 #include "extern.h"
     50 
     51 /* Return true if the db file is valid, else false */
     52 int
     53 testdb()
     54 {
     55 	register DB *db;
     56 	register int cc, kd, ret, dbversionlen;
     57 	register char *cp, *uf;
     58 	DBT rec;
     59 	struct nlist nitem;
     60 	char dbname[MAXPATHLEN], dbversion[_POSIX2_LINE_MAX];
     61 	char kversion[_POSIX2_LINE_MAX];
     62 
     63 	ret = 0;
     64 	db = NULL;
     65 
     66 	if ((kd = open(_PATH_KMEM, O_RDONLY, 0)) < 0)
     67 		goto close;
     68 
     69 	uf = _PATH_UNIX;
     70 	if ((cp = rindex(uf, '/')) != 0)
     71 		uf = cp + 1;
     72 	(void) snprintf(dbname, sizeof(dbname), "%skvm_%s.db", _PATH_VARDB, uf);
     73 	if ((db = dbopen(dbname, O_RDONLY, 0, DB_HASH, NULL)) == NULL)
     74 		goto close;
     75 
     76 	/* Read the version out of the database */
     77 	rec.data = VRS_KEY;
     78 	rec.size = sizeof(VRS_KEY) - 1;
     79 	if ((db->get)(db, &rec, &rec, 0))
     80 		goto close;
     81 	if (rec.data == 0 || rec.size > sizeof(dbversion))
     82 		goto close;
     83 	bcopy(rec.data, dbversion, rec.size);
     84 	dbversionlen = rec.size;
     85 
     86 	/* Read version string from kernel memory */
     87 	rec.data = VRS_SYM;
     88 	rec.size = sizeof(VRS_SYM) - 1;
     89 	if ((db->get)(db, &rec, &rec, 0))
     90 		goto close;
     91 	if (rec.data == 0 || rec.size != sizeof(struct nlist))
     92 		goto close;
     93 	bcopy(rec.data, &nitem, sizeof(nitem));
     94 	/*
     95 	 * Theoretically possible for lseek to be seeking to -1.  Not
     96 	 * that it's something to lie awake nights about, however.
     97 	 */
     98 	errno = 0;
     99 	if (lseek(kd, (off_t)nitem.n_value, SEEK_SET) == -1 && errno != 0)
    100 		goto close;
    101 	cc = read(kd, kversion, sizeof(kversion));
    102 	if (cc < 0 || cc != sizeof(kversion))
    103 		goto close;
    104 
    105 	/* If they match, we win */
    106 	ret = bcmp(dbversion, kversion, dbversionlen) == 0;
    107 
    108 close:	if (kd >= 0)
    109 		(void)close(kd);
    110 	if (db)
    111 		(void)(db->close)(db);
    112 	return (ret);
    113 }
    114