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wireshark/wsutil/safe-math.h

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ftypes: Use C23 compatible checked arithmetic Add a header-only library for C23 checked integer arithmetic from https://github.com/jart/jtckdint Use it in the ftypes handling instead of the implementations in safe-math. Note that the return value is opposite (true means overflow occurred). C23 stdckdint.h (and jtckdint.h) do not include implementations for div, mod, and unary negation, where division by zero and, for signed integers, cases like INT_MIN / -1 which overflow from INT_MAX + 1 for 2's complement. Those cases have to be handled separately. Note that the divide by zero case, unlike the others, can't really have a "this is what the answer is if you just want the result to wrap around," though that doesn't matter for the ftypes/dfilter. Ping #20144
2025-04-29 23:08:15 -04:00
/* Overflow-safe math helper macros
dfilter: Add binary arithmetic (add/subtract) Add support for display filter binary addition and subtraction. The grammar is intentionally kept simple for now. The use case is to add a constant to a protocol field, or (maybe) add two fields in an expression. We use signed arithmetic with unsigned numbers, checking for overflow and casting where necessary to do the conversion. We could legitimately opt to use traditional modular arithmetic instead (like C) and if it turns out that that is more useful for some reason we may want to in the future. Fixes #15504.
2022-02-27 14:47:31 +00:00
*
* To the extent possible under law, the authors have waived all
* copyright and related or neighboring rights to this code. For
* details, see the Creative Commons Zero 1.0 Universal license at
* https://creativecommons.org/publicdomain/zero/1.0/
*/
ftypes: Use C23 compatible checked arithmetic Add a header-only library for C23 checked integer arithmetic from https://github.com/jart/jtckdint Use it in the ftypes handling instead of the implementations in safe-math. Note that the return value is opposite (true means overflow occurred). C23 stdckdint.h (and jtckdint.h) do not include implementations for div, mod, and unary negation, where division by zero and, for signed integers, cases like INT_MIN / -1 which overflow from INT_MAX + 1 for 2's complement. Those cases have to be handled separately. Note that the divide by zero case, unlike the others, can't really have a "this is what the answer is if you just want the result to wrap around," though that doesn't matter for the ftypes/dfilter. Ping #20144
2025-04-29 23:08:15 -04:00
#pragma once
dfilter: Add binary arithmetic (add/subtract) Add support for display filter binary addition and subtraction. The grammar is intentionally kept simple for now. The use case is to add a constant to a protocol field, or (maybe) add two fields in an expression. We use signed arithmetic with unsigned numbers, checking for overflow and casting where necessary to do the conversion. We could legitimately opt to use traditional modular arithmetic instead (like C) and if it turns out that that is more useful for some reason we may want to in the future. Fixes #15504.
2022-02-27 14:47:31 +00:00
dfilter: Use safe-math.h with time ftypes
2023-06-18 19:23:58 +01:00
#include <setjmp.h>
#define ws_safe_op_jmp(op, res, a, b, env) \
do { \
ftypes: Use C23 compatible checked arithmetic Add a header-only library for C23 checked integer arithmetic from https://github.com/jart/jtckdint Use it in the ftypes handling instead of the implementations in safe-math. Note that the return value is opposite (true means overflow occurred). C23 stdckdint.h (and jtckdint.h) do not include implementations for div, mod, and unary negation, where division by zero and, for signed integers, cases like INT_MIN / -1 which overflow from INT_MAX + 1 for 2's complement. Those cases have to be handled separately. Note that the divide by zero case, unlike the others, can't really have a "this is what the answer is if you just want the result to wrap around," though that doesn't matter for the ftypes/dfilter. Ping #20144
2025-04-29 23:08:15 -04:00
if(ckd_##op(res, a, b)) { \
dfilter: Use safe-math.h with time ftypes
2023-06-18 19:23:58 +01:00
longjmp(env, 1); \
} \
} while (0)
#define ws_safe_add_jmp(res, a, b, env) ws_safe_op_jmp(add, res, a, b, env)
#define ws_safe_sub_jmp(res, a, b, env) ws_safe_op_jmp(sub, res, a, b, env)
#define ws_safe_mul_jmp(res, a, b, env) ws_safe_op_jmp(mul, res, a, b, env)
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