dce3f3406f
This change addresses the issue of https://github.com/boostorg/multiprecision/issues/553, the fix prevents an application from crash due to an exception thrown in a function marked `noexcept`, when converting a `cpp_int` to a float, if the value of this `cpp_int` cannot be represented with a float. this issue is a regression in Boost 1.79, see more details at https://github.com/boostorg/multiprecision/pull/618 Signed-off-by: Kefu Chai <tchaikov@gmail.com>
78 lines
4 KiB
Diff
78 lines
4 KiB
Diff
From ea786494db78efdf178cbe36810f3326156e3347 Mon Sep 17 00:00:00 2001
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From: Kefu Chai <tchaikov@gmail.com>
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Date: Fri, 3 May 2024 15:08:05 +0800
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Subject: [PATCH] make sure eval_convert_to() do not terminate with super large
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number
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this change is a follow-up of d51f2e9dbb. it intends to
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address the exception thrown in a noexcept functon.
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a minimal reproducer looks like
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```c++
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int main() {
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std::string s = "32767456456456456456545678943512357658768763546575675";
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boost::multiprecision::cpp_int num(s);
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std::cout << num.convert_to<float>() << std::endl;
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}
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```
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since boost 1.79, the code above terminates like
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```
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Program returned: 139
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Program stderr
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terminate called after throwing an instance of 'boost::wrapexcept<std::domain_error>'
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what(): Error in function float_next<float>(float): Argument must be finite, but got inf
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Program terminated with signal: SIGSEGV
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```
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because `float_next_imp()` throws 'boost::wrapexcept<std::domain_error>'
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if the number is NAN of INF. and `eval_convert_to()` is marked as
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`noexcept(boost::multiprecision::detail::is_arithmetic<R>::value &&
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std::numeric_limits<R>::has_infinity)`,
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but only `overflow_error` is ignored in the policy passed to
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`float_next()`.
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so, in this change, `std::domain_error` is ignored as well, so that
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``num.convert_to<float>()` returns a NaN in this case.
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Refs #553
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Signed-off-by: Kefu Chai <tchaikov@gmail.com>
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---
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include/boost/multiprecision/cpp_int/misc.hpp | 9 ++++++---
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1 file changed, 6 insertions(+), 3 deletions(-)
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diff --git a/include/boost/multiprecision/cpp_int/misc.hpp b/include/boost/multiprecision/cpp_int/misc.hpp
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index cdae2f75..a8a76400 100644
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--- a/boost/multiprecision/cpp_int/misc.hpp
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+++ b/boost/multiprecision/cpp_int/misc.hpp
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@@ -184,7 +184,9 @@ eval_convert_to(R* result, const cpp_int_backend<MinBits1, MaxBits1, SignType1,
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template <class R, std::size_t MinBits1, std::size_t MaxBits1, cpp_integer_type SignType1, cpp_int_check_type Checked1, class Allocator1>
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inline BOOST_MP_CXX14_CONSTEXPR typename std::enable_if<std::is_floating_point<R>::value && !is_trivial_cpp_int<cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1> >::value, void>::type
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-eval_convert_to(R* result, const cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>& backend) noexcept(boost::multiprecision::detail::is_arithmetic<R>::value && std::numeric_limits<R>::has_infinity)
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+eval_convert_to(R* result, const cpp_int_backend<MinBits1, MaxBits1, SignType1, Checked1, Allocator1>& backend) noexcept(boost::multiprecision::detail::is_arithmetic<R>::value &&
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+ (std::numeric_limits<R>::has_infinity ||
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+ std::numeric_limits<R>::has_quiet_NaN))
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{
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BOOST_MP_FLOAT128_USING using std::ldexp;
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if (eval_is_zero(backend))
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@@ -244,10 +246,11 @@ eval_convert_to(R* result, const cpp_int_backend<MinBits1, MaxBits1, SignType1,
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if ((eval_lsb_imp(backend) < static_cast<std::size_t>(bits)) || eval_bit_test(backend, static_cast<std::size_t>(bits + 1)))
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{
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#ifdef BOOST_MP_MATH_AVAILABLE
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- BOOST_IF_CONSTEXPR(std::numeric_limits<R>::has_infinity)
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+ BOOST_IF_CONSTEXPR(std::numeric_limits<R>::has_infinity || std::numeric_limits<R>::has_quiet_NaN)
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{
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// Must NOT throw:
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- *result = boost::math::float_next(*result, boost::math::policies::make_policy(boost::math::policies::overflow_error<boost::math::policies::ignore_error>()));
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+ *result = boost::math::float_next(*result, boost::math::policies::make_policy(boost::math::policies::overflow_error<boost::math::policies::ignore_error>(),
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+ boost::math::policies::domain_error<boost::math::policies::ignore_error>()));
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}
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else
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{
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--
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2.44.0
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