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Change internal_storage() implementation to avoid UBSan errors when N is zero.

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Ion Gaztañaga
2024-01-03 02:34:58 +01:00
parent fb822f0435
commit 3c8c087eb7
1 changed files with 42 additions and 36 deletions
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78
include/boost/container/small_vector.hpp
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@@ -46,6 +46,8 @@
#include <initializer_list> //for std::initializer_list
#endif
#include <cstddef> //offsetof
namespace boost {
namespace container {
@@ -452,61 +454,65 @@ struct small_vector_storage_definer
typedef small_vector_storage<T, N, final_alignment> type;
};
/// Figure out the offset of the first element. Idea taken from LLVM's SmallVector
template <class T, class SecAlloc, class Options>
struct small_vector_storage_strawman
: public small_vector_base<T, SecAlloc, Options>
, public small_vector_storage_definer<T, 1, Options>::type
struct small_vector_storage_offset
{
typedef typename small_vector_storage_definer<T, 1, Options>::type sm_storage_t;
typedef small_vector_base<T, SecAlloc, Options> base_type;
typedef typename small_vector_storage_definer<T, 1, Options>::type storage_type;
typename dtl::aligned_storage
< sizeof(base_type), dtl::alignment_of<base_type>::value
>::type base;
typename dtl::aligned_storage
< sizeof(storage_type), dtl::alignment_of<storage_type>::value
> ::type storage;
};
template <class T, class SecAlloc, class Options>
inline std::size_t get_small_vector_storage_offset()
{
typedef small_vector_storage_offset<T, SecAlloc, Options> struct_type;
return offsetof(struct_type, storage);
}
#if defined(BOOST_GCC) && (BOOST_GCC >= 40600)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wcast-align"
#pragma GCC diagnostic ignored "-Wstrict-aliasing"
#endif
//Internal storage hack
template<class T, class VoidAlloc, class Options>
inline typename small_vector_allocator<T, VoidAlloc, Options>::const_pointer
small_vector_allocator<T, VoidAlloc, Options>::internal_storage() const BOOST_NOEXCEPT_OR_NOTHROW
{
typedef small_vector_storage_strawman<T, allocator_type, Options> strawman_t;
typedef typename strawman_t::sm_storage_t sm_storage_t;
//These warnings are false positives, as we know the alignment is correct
//and aligned storage is allowed to hold any type
#if defined(BOOST_GCC) && (BOOST_GCC >= 40600)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wcast-align"
#pragma GCC diagnostic ignored "-Wstrict-aliasing"
#endif
const vector_type& v = reinterpret_cast<const vector_type&>(*this);
BOOST_ASSERT((std::size_t(this) % dtl::alignment_of<strawman_t>::value) == 0);
const strawman_t &straw = static_cast<const strawman_t&>(v);
const sm_storage_t& stor = static_cast<const sm_storage_t&>(straw);
return boost::intrusive::pointer_traits<const_pointer>::pointer_to(*((const T*)stor.m_storage.data));
#if defined(BOOST_GCC) && (BOOST_GCC >= 40600)
#pragma GCC diagnostic pop
#endif
BOOST_ASSERT((std::size_t(this) % dtl::alignment_of< small_vector_storage_offset<T, allocator_type, Options> >::value) == 0);
const char *addr = reinterpret_cast<const char*>(&v);
typedef typename boost::intrusive::pointer_traits<pointer>::template rebind_pointer<const char>::type const_char_pointer;
const_void_pointer vptr = boost::intrusive::pointer_traits<const_char_pointer>::pointer_to(*addr)
+ get_small_vector_storage_offset<T, allocator_type, Options>();
return boost::intrusive::pointer_traits<const_pointer>::static_cast_from(vptr);
}
template <class T, class VoidAlloc, class Options>
inline typename small_vector_allocator<T, VoidAlloc, Options>::pointer
small_vector_allocator<T, VoidAlloc, Options>::internal_storage() BOOST_NOEXCEPT_OR_NOTHROW
{
typedef small_vector_storage_strawman<T, allocator_type, Options> strawman_t;
typedef typename strawman_t::sm_storage_t sm_storage_t;
#if defined(BOOST_GCC) && (BOOST_GCC >= 40600)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wcast-align"
#pragma GCC diagnostic ignored "-Wstrict-aliasing"
#endif
vector_type& v = reinterpret_cast<vector_type&>(*this);
BOOST_ASSERT((std::size_t(this) % dtl::alignment_of<strawman_t>::value) == 0);
strawman_t &straw = static_cast<strawman_t&>(v);
sm_storage_t& stor = static_cast<sm_storage_t&>(straw);
return boost::intrusive::pointer_traits<pointer>::pointer_to(*((T*)stor.m_storage.data));
#if defined(BOOST_GCC) && (BOOST_GCC >= 40600)
#pragma GCC diagnostic pop
#endif
BOOST_ASSERT((std::size_t(this) % dtl::alignment_of< small_vector_storage_offset<T, allocator_type, Options> >::value) == 0);
char* addr = reinterpret_cast<char*>(&v);
typedef typename boost::intrusive::pointer_traits<pointer>::template rebind_pointer<char>::type char_pointer;
void_pointer vptr = boost::intrusive::pointer_traits<char_pointer>::pointer_to(*addr)
+ get_small_vector_storage_offset<T, allocator_type, Options>();
return boost::intrusive::pointer_traits<pointer>::static_cast_from(vptr);
}
#if defined(BOOST_GCC) && (BOOST_GCC >= 40600)
#pragma GCC diagnostic pop
#endif
#endif //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED