summaryrefslogtreecommitdiff
path: root/src/os/os_uid.c
blob: 2e5c9f87af98853a23c526639e6045a72223a091 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 2001, 2012 Oracle and/or its affiliates.  All rights reserved.
 *
 * $Id$
 */

#include "db_config.h"

#include "db_int.h"

/*
 * __os_unique_id --
 *	Return a unique 32-bit value.
 *
 * PUBLIC: void __os_unique_id __P((ENV *, u_int32_t *));
 */
void
__os_unique_id(env, idp)
	ENV *env;
	u_int32_t *idp;
{
	DB_ENV *dbenv;
	db_timespec v;
	pid_t pid;
	u_int32_t id;

	*idp = 0;

	dbenv = env == NULL ? NULL : env->dbenv;

	/*
	 * Our randomized value is comprised of our process ID, the current
	 * time of day and a stack address, all XOR'd together.
	 */
	__os_id(dbenv, &pid, NULL);
	__os_gettime(env, &v, 1);

	id = (u_int32_t)pid ^
	    (u_int32_t)v.tv_sec ^ (u_int32_t)v.tv_nsec ^ P_TO_UINT32(&pid);

	/*
	 * We could try and find a reasonable random-number generator, but
	 * that's not all that easy to do.  Seed and use srand()/rand(), if
	 * we can find them.
	 */
	if (DB_GLOBAL(uid_init) == 0) {
		DB_GLOBAL(uid_init) = 1;
		srand((u_int)id);
	}
	id ^= (u_int)rand();

	*idp = id;
}