67 lines
2.7 KiB
C
67 lines
2.7 KiB
C
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/**
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* @file overflow.h
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* @author Ambroz Bizjak <ambrop7@gmail.com>
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*
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* @section LICENSE
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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 are met:
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* 1. 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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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the author nor the
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* names of its contributors may be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* @section DESCRIPTION
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*
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* Functions for checking for overflow of integer addition.
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*/
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#ifndef BADVPN_MISC_OVERFLOW_H
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#define BADVPN_MISC_OVERFLOW_H
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#include <limits.h>
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#include <stdint.h>
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#define DEFINE_UNSIGNED_OVERFLOW(_name, _type, _max) \
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static int add_ ## _name ## _overflows (_type a, _type b) \
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{\
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return (b > _max - a); \
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}
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#define DEFINE_SIGNED_OVERFLOW(_name, _type, _min, _max) \
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static int add_ ## _name ## _overflows (_type a, _type b) \
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{\
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if ((a < 0) ^ (b < 0)) return 0; \
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if (a < 0) return -(a < _min - b); \
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return (a > _max - b); \
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}
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DEFINE_UNSIGNED_OVERFLOW(uint, unsigned int, UINT_MAX)
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DEFINE_UNSIGNED_OVERFLOW(uint8, uint8_t, UINT8_MAX)
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DEFINE_UNSIGNED_OVERFLOW(uint16, uint16_t, UINT16_MAX)
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DEFINE_UNSIGNED_OVERFLOW(uint32, uint32_t, UINT32_MAX)
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DEFINE_UNSIGNED_OVERFLOW(uint64, uint64_t, UINT64_MAX)
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DEFINE_SIGNED_OVERFLOW(int, int, INT_MIN, INT_MAX)
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DEFINE_SIGNED_OVERFLOW(int8, int8_t, INT8_MIN, INT8_MAX)
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DEFINE_SIGNED_OVERFLOW(int16, int16_t, INT16_MIN, INT16_MAX)
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DEFINE_SIGNED_OVERFLOW(int32, int32_t, INT32_MIN, INT32_MAX)
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DEFINE_SIGNED_OVERFLOW(int64, int64_t, INT64_MIN, INT64_MAX)
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#endif
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