This is xnu-11215.1.10. See this file in:
//
// Tests for
// bounded_ptr& operator-=(std::ptrdiff_t n);
//
#include <libkern/c++/bounded_ptr.h>
#include <array>
#include <darwintest.h>
#include <darwintest_utils.h>
#include "test_utils.h"
#define _assert(...) T_ASSERT_TRUE((__VA_ARGS__), # __VA_ARGS__)
struct T { int i; };
namespace {
struct tracking_policy {
static bool did_trap;
static void
trap(char const* msg)
{
did_trap = true;
}
};
bool tracking_policy::did_trap = false;
}
template <typename T, typename QualT>
static void
tests()
{
std::array<T, 5> array = {T{0}, T{1}, T{2}, T{3}, T{4}};
// Subtract-assign positive offsets
// T{0} T{1} T{2} T{3} T{4} <one-past-last>
// ^ ^
// | |
// begin end,ptr
{
test_bounded_ptr<QualT> ptr(array.end(), array.begin(), array.end());
auto& ref = ptr -= 0;
_assert(&ref == &ptr);
_assert(ptr == array.end());
}
{
test_bounded_ptr<QualT> ptr(array.end(), array.begin(), array.end());
auto& ref = ptr -= 1;
_assert(&ref == &ptr);
_assert(&*ptr == &array[4]);
}
{
test_bounded_ptr<QualT> ptr(array.end(), array.begin(), array.end());
auto& ref = ptr -= 2;
_assert(&ref == &ptr);
_assert(&*ptr == &array[3]);
}
{
test_bounded_ptr<QualT> ptr(array.end(), array.begin(), array.end());
auto& ref = ptr -= 3;
_assert(&ref == &ptr);
_assert(&*ptr == &array[2]);
}
{
test_bounded_ptr<QualT> ptr(array.end(), array.begin(), array.end());
auto& ref = ptr -= 4;
_assert(&ref == &ptr);
_assert(&*ptr == &array[1]);
}
{
test_bounded_ptr<QualT> ptr(array.end(), array.begin(), array.end());
auto& ref = ptr -= 5;
_assert(&ref == &ptr);
_assert(&*ptr == &array[0]);
}
// Subtract-assign negative offsets
// T{0} T{1} T{2} T{3} T{4} <one-past-last>
// ^ ^
// | |
// begin,ptr end
{
test_bounded_ptr<QualT> ptr(array.begin(), array.begin(), array.end());
auto& ref = ptr -= 0;
_assert(&ref == &ptr);
_assert(&*ptr == &array[0]);
}
{
test_bounded_ptr<QualT> ptr(array.begin(), array.begin(), array.end());
auto& ref = ptr -= -1;
_assert(&ref == &ptr);
_assert(&*ptr == &array[1]);
}
{
test_bounded_ptr<QualT> ptr(array.begin(), array.begin(), array.end());
auto& ref = ptr -= -2;
_assert(&ref == &ptr);
_assert(&*ptr == &array[2]);
}
{
test_bounded_ptr<QualT> ptr(array.begin(), array.begin(), array.end());
auto& ref = ptr -= -3;
_assert(&ref == &ptr);
_assert(&*ptr == &array[3]);
}
{
test_bounded_ptr<QualT> ptr(array.begin(), array.begin(), array.end());
auto& ref = ptr -= -4;
_assert(&ref == &ptr);
_assert(&*ptr == &array[4]);
}
{
test_bounded_ptr<QualT> ptr(array.begin(), array.begin(), array.end());
auto& ref = ptr -= -5;
_assert(&ref == &ptr);
_assert(ptr == array.end());
}
// Make sure we trap on arithmetic overflow in the number of bytes calculation
{
std::ptrdiff_t sizeof_T = sizeof(T); // avoid promotion to unsigned in calculations
// largest (most positive) n for the number of bytes `n * sizeof(T)` not to overflow ptrdiff_t
std::ptrdiff_t max_n = std::numeric_limits<std::ptrdiff_t>::max() / sizeof_T;
// smallest (most negative) n for the number of bytes `n * sizeof(T)` not to overflow ptrdiff_t
std::ptrdiff_t min_n = std::numeric_limits<std::ptrdiff_t>::min() / sizeof_T;
// Overflow with a positive offset
{
libkern::bounded_ptr<QualT, tracking_policy> ptr(array.begin(), array.begin(), array.end());
tracking_policy::did_trap = false;
ptr -= max_n + 1;
_assert(tracking_policy::did_trap);
}
// Overflow with a negative offset
{
libkern::bounded_ptr<QualT, tracking_policy> ptr(array.begin(), array.begin(), array.end());
tracking_policy::did_trap = false;
ptr -= min_n - 1;
_assert(tracking_policy::did_trap);
}
}
// Make sure we trap on arithmetic overflow in the offset calculation
//
// To avoid running into the overflow of `n * sizeof(T)` when ptrdiff_t
// is the same size as int32_t, we test the offset overflow check by
// successive subtraction of smaller offsets.
//
// We basically push the offset right to its limit, and then push it
// past its limit to watch it overflow.
{
std::int64_t sizeof_T = sizeof(T); // avoid promotion to unsigned in calculations
// largest (most positive) n for the number of bytes `n * sizeof(T)` not to overflow the int32_t offset
std::int64_t max_n = std::numeric_limits<std::int32_t>::max() / sizeof_T;
// smallest (most negative) n for the number of bytes `n * sizeof(T)` not to overflow the int32_t offset
std::int64_t min_n = std::numeric_limits<std::int32_t>::min() / sizeof_T;
// Subtract positive offsets
{
libkern::bounded_ptr<QualT, tracking_policy> ptr(array.begin(), array.begin(), array.end());
tracking_policy::did_trap = false;
ptr -= static_cast<ptrdiff_t>(-min_n / 2);
_assert(!tracking_policy::did_trap);
ptr -= static_cast<ptrdiff_t>(-min_n / 2);
_assert(!tracking_policy::did_trap);
ptr -= (-min_n % 2);
_assert(!tracking_policy::did_trap); // offset is now right at its negative limit
ptr -= 1;
_assert(tracking_policy::did_trap);
}
// Subtract negative offsets
{
libkern::bounded_ptr<QualT, tracking_policy> ptr(array.begin(), array.begin(), array.end());
tracking_policy::did_trap = false;
ptr -= static_cast<ptrdiff_t>(-max_n / 2);
_assert(!tracking_policy::did_trap);
ptr -= static_cast<ptrdiff_t>(-max_n / 2);
_assert(!tracking_policy::did_trap);
ptr -= (-max_n % 2);
_assert(!tracking_policy::did_trap); // offset is now right at its positive limit
ptr -= -1;
_assert(tracking_policy::did_trap);
}
}
}
T_DECL(arith_subtract_assign, "bounded_ptr.arith.subtract_assign", T_META_TAG_VM_PREFERRED) {
tests<T, T>();
tests<T, T const>();
tests<T, T volatile>();
tests<T, T const volatile>();
}