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1bf36f177b
This function depends on genrand.c, which depends on lib/crypto. This way the other IDR tree code can be used without lib/crypto. While doing this, create idtree.h and idtree_random.h and clean up the includes. Signed-off-by: Martin Schwenke <martin@meltin.net> Reviewed-by: Volker Lendecke <vl@samba.org>
61 lines
1.8 KiB
C
61 lines
1.8 KiB
C
/*
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Unix SMB/CIFS implementation.
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very efficient functions to manage mapping a id (such as a fnum) to
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a pointer. This is used for fnum and search id allocation.
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Copyright (C) Andrew Tridgell 2004
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This code is derived from lib/idr.c in the 2.6 Linux kernel, which was
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written by Jim Houston jim.houston@ccur.com, and is
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Copyright (C) 2002 by Concurrent Computer Corporation
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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see the section marked "public interface" below for documentation
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*/
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/**
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* @file
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*/
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#include "replace.h"
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#include "samba_util.h" /* generate_random() */
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#include "idtree.h"
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#include "idtree_random.h"
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/**
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allocate a new id randomly in the given range
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*/
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_PUBLIC_ int idr_get_new_random(struct idr_context *idp, void *ptr, int limit)
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{
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int id;
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/* first try a random starting point in the whole range, and if that fails,
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then start randomly in the bottom half of the range. This can only
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fail if the range is over half full, and finally fallback to any
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free id */
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id = idr_get_new_above(idp, ptr, 1+(generate_random() % limit), limit);
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if (id == -1) {
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id = idr_get_new_above(idp, ptr, 1+(generate_random()%(limit/2)), limit);
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}
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if (id == -1) {
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id = idr_get_new_above(idp, ptr, 1, limit);
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}
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return id;
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}
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