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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 17:20:00 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-19 17:20:00 +0000
commit8daa83a594a2e98f39d764422bfbdbc62c9efd44 (patch)
tree4099e8021376c7d8c05bdf8503093d80e9c7bad0 /lib/util/idtree_random.c
parentInitial commit. (diff)
downloadsamba-8daa83a594a2e98f39d764422bfbdbc62c9efd44.tar.xz
samba-8daa83a594a2e98f39d764422bfbdbc62c9efd44.zip
Adding upstream version 2:4.20.0+dfsg.upstream/2%4.20.0+dfsg
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'lib/util/idtree_random.c')
-rw-r--r--lib/util/idtree_random.c68
1 files changed, 68 insertions, 0 deletions
diff --git a/lib/util/idtree_random.c b/lib/util/idtree_random.c
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+/*
+ Unix SMB/CIFS implementation.
+
+ very efficient functions to manage mapping a id (such as a fnum) to
+ a pointer. This is used for fnum and search id allocation.
+
+ Copyright (C) Andrew Tridgell 2004
+
+ This code is derived from lib/idr.c in the 2.6 Linux kernel, which was
+ written by Jim Houston jim.houston@ccur.com, and is
+ Copyright (C) 2002 by Concurrent Computer Corporation
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+/*
+ see the section marked "public interface" below for documentation
+*/
+
+/**
+ * @file
+ */
+
+#include "replace.h"
+#include "samba_util.h" /* generate_random() */
+#include "idtree.h"
+#include "idtree_random.h"
+
+/**
+ allocate a new id randomly in the given range
+*/
+_PUBLIC_ int idr_get_new_random(struct idr_context *idp,
+ void *ptr,
+ int starting_id,
+ int limit)
+{
+ int id;
+
+ /* first try a random starting point in the whole range, and if that fails,
+ then start randomly in the bottom half of the range. This can only
+ fail if the range is over half full, and finally fallback to any
+ free id */
+ id = idr_get_new_above(
+ idp, ptr, starting_id+(generate_random() % limit), limit);
+ if (id == -1) {
+ id = idr_get_new_above(
+ idp,
+ ptr,
+ starting_id+(generate_random()%(limit/2)),
+ limit);
+ }
+ if (id == -1) {
+ id = idr_get_new_above(idp, ptr, starting_id, limit);
+ }
+
+ return id;
+}