fed2659869
A __size_mul_overflow utility is used to take advantage of the checked overflow intrinsics in Clang and GCC (>= 5). The fallback for older compilers is the optimized but less than ideal overflow checking pattern used in OpenBSD. Change-Id: Ibb0d4fd9b5acb67983e6a9f46844c2fd444f7e69
47 lines
2 KiB
C++
47 lines
2 KiB
C++
/*
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* Copyright (C) 2015 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#undef _FORTIFY_SOURCE
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#include <stdio.h>
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#include <sys/cdefs.h>
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#include "private/libc_logging.h"
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extern "C" size_t __fwrite_chk(const void * __restrict buf, size_t size, size_t count,
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FILE * __restrict stream, size_t buf_size) {
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size_t total;
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if (__predict_false(__size_mul_overflow(size, count, &total))) {
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// overflow: trigger the error path in fwrite
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return fwrite(buf, size, count, stream);
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}
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if (__predict_false(total > buf_size)) {
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__fortify_chk_fail("fwrite: prevented read past end of buffer", 0);
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}
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return fwrite(buf, size, count, stream);
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}
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