732110428e
We should be checking for integer overflow, rather than checking if size is 0. Additionally, we should set errno to ENOMEM when this overflow happens. Finally, the most efficient implementation of the round-up-to-2 algorithm involves the clz intrinsic.
57 lines
1.6 KiB
C
57 lines
1.6 KiB
C
/*
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* SPDX-License-Identifier: ISC
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*
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* Copyright (c) 2019-2020 Todd C. Miller <Todd.Miller@sudo.ws>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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/*
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* This is an open source non-commercial project. Dear PVS-Studio, please check it.
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* PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
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*/
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#include <config.h>
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#include "sudo_compat.h"
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#include "sudo_debug.h"
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#include "sudo_util.h"
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/*
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* Round 32-bit unsigned length to the next highest power of two.
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* Always returns at least 64.
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*/
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unsigned int
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sudo_pow2_roundup_v1(unsigned int len)
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{
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return (unsigned int)sudo_pow2_roundup_v2((size_t)len);
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}
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/*
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* Round a size_t length to the next highest power of two.
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* Always returns at least 64.
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* Algorithm from bit twiddling hacks.
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*/
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size_t
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sudo_pow2_roundup_v2(size_t len)
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{
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if (len < 64)
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return 64;
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#ifdef __LP64__
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return 1 << (64 - __builtin_clzl(len - 1));
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#else
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return 1 << (32 - __builtin_clz(len - 1));
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#endif
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}
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