Import BSDDB 4.7.25 (as of svn r89086)

os/os_uid.c

@@ -0,0 +1,55 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 2001,2008 Oracle.  All rights reserved.
+ *
+ * $Id: os_uid.c 63573 2008-05-23 21:43:21Z trent.nelson $
+ */
+
+#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;
+}