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Unverified Commit f883ddd1 authored by Niels Lohmann's avatar Niels Lohmann Committed by GitHub
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Merge pull request #2872 from nlohmann/issue2865 

Fix memory leak in to_json
parents c9c5c016 3e4723a4
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Showing with 152 additions and 72 deletions
include/nlohmann/detail/conversions/to_json.hpp
View file @ f883ddd1
......@@ -22,6 +22,13 @@ namespace detail
// constructors //
//////////////////
/*
* Note all external_constructor<>::construct functions need to call
* j.m_value.destroy(j.m_type) to avoid a memory leak in case j contains an
* allocated value (e.g., a string). See bug issue
* https://github.com/nlohmann/json/issues/2865 for more information.
*/
template<value_t> struct external_constructor;
template<>
......@@ -30,6 +37,7 @@ struct external_constructor<value_t::boolean>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::boolean_t b) noexcept
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::boolean;
j.m_value = b;
j.assert_invariant();
......@@ -42,6 +50,7 @@ struct external_constructor<value_t::string>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, const typename BasicJsonType::string_t& s)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::string;
j.m_value = s;
j.assert_invariant();
......@@ -50,6 +59,7 @@ struct external_constructor<value_t::string>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::string_t&& s)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::string;
j.m_value = std::move(s);
j.assert_invariant();
......@@ -60,6 +70,7 @@ struct external_constructor<value_t::string>
int > = 0 >
static void construct(BasicJsonType& j, const CompatibleStringType& str)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::string;
j.m_value.string = j.template create<typename BasicJsonType::string_t>(str);
j.assert_invariant();
......@@ -72,6 +83,7 @@ struct external_constructor<value_t::binary>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, const typename BasicJsonType::binary_t& b)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::binary;
j.m_value = typename BasicJsonType::binary_t(b);
j.assert_invariant();
......@@ -80,6 +92,7 @@ struct external_constructor<value_t::binary>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::binary_t&& b)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::binary;
j.m_value = typename BasicJsonType::binary_t(std::move(b));;
j.assert_invariant();
......@@ -92,6 +105,7 @@ struct external_constructor<value_t::number_float>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::number_float_t val) noexcept
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::number_float;
j.m_value = val;
j.assert_invariant();
......@@ -104,6 +118,7 @@ struct external_constructor<value_t::number_unsigned>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::number_unsigned_t val) noexcept
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::number_unsigned;
j.m_value = val;
j.assert_invariant();
......@@ -116,6 +131,7 @@ struct external_constructor<value_t::number_integer>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::number_integer_t val) noexcept
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::number_integer;
j.m_value = val;
j.assert_invariant();
......@@ -128,6 +144,7 @@ struct external_constructor<value_t::array>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, const typename BasicJsonType::array_t& arr)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::array;
j.m_value = arr;
j.set_parents();
......@@ -137,6 +154,7 @@ struct external_constructor<value_t::array>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::array_t&& arr)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::array;
j.m_value = std::move(arr);
j.set_parents();
......@@ -150,6 +168,8 @@ struct external_constructor<value_t::array>
{
using std::begin;
using std::end;
j.m_value.destroy(j.m_type);
j.m_type = value_t::array;
j.m_value.array = j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr));
j.set_parents();
......@@ -159,6 +179,7 @@ struct external_constructor<value_t::array>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, const std::vector<bool>& arr)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::array;
j.m_value = value_t::array;
j.m_value.array->reserve(arr.size());
......@@ -174,6 +195,7 @@ struct external_constructor<value_t::array>
enable_if_t<std::is_convertible<T, BasicJsonType>::value, int> = 0>
static void construct(BasicJsonType& j, const std::valarray<T>& arr)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::array;
j.m_value = value_t::array;
j.m_value.array->resize(arr.size());
......@@ -192,6 +214,7 @@ struct external_constructor<value_t::object>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, const typename BasicJsonType::object_t& obj)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::object;
j.m_value = obj;
j.set_parents();
......@@ -201,6 +224,7 @@ struct external_constructor<value_t::object>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::object;
j.m_value = std::move(obj);
j.set_parents();
......@@ -214,6 +238,7 @@ struct external_constructor<value_t::object>
using std::begin;
using std::end;
j.m_value.destroy(j.m_type);
j.m_type = value_t::object;
j.m_value.object = j.template create<typename BasicJsonType::object_t>(begin(obj), end(obj));
j.set_parents();
......
include/nlohmann/json.hpp
View file @ f883ddd1
......@@ -1131,53 +1131,55 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
binary = create<binary_t>(std::move(value));
}
void destroy(value_t t) noexcept
void destroy(value_t t)
{
// flatten the current json_value to a heap-allocated stack
std::vector<basic_json> stack;
// move the top-level items to stack
if (t == value_t::array)
{
stack.reserve(array->size());
std::move(array->begin(), array->end(), std::back_inserter(stack));
}
else if (t == value_t::object)
{
stack.reserve(object->size());
for (auto&& it : *object)
{
stack.push_back(std::move(it.second));
}
}
while (!stack.empty())
if (t == value_t::array || t == value_t::object)
{
// move the last item to local variable to be processed
basic_json current_item(std::move(stack.back()));
stack.pop_back();
// flatten the current json_value to a heap-allocated stack
std::vector<basic_json> stack;
// if current_item is array/object, move
// its children to the stack to be processed later
if (current_item.is_array())
// move the top-level items to stack
if (t == value_t::array)
{
std::move(current_item.m_value.array->begin(), current_item.m_value.array->end(),
std::back_inserter(stack));
current_item.m_value.array->clear();
stack.reserve(array->size());
std::move(array->begin(), array->end(), std::back_inserter(stack));
}
else if (current_item.is_object())
else
{
for (auto&& it : *current_item.m_value.object)
stack.reserve(object->size());
for (auto&& it : *object)
{
stack.push_back(std::move(it.second));
}
current_item.m_value.object->clear();
}
// it's now safe that current_item get destructed
// since it doesn't have any children
while (!stack.empty())
{
// move the last item to local variable to be processed
basic_json current_item(std::move(stack.back()));
stack.pop_back();
// if current_item is array/object, move
// its children to the stack to be processed later
if (current_item.is_array())
{
std::move(current_item.m_value.array->begin(), current_item.m_value.array->end(), std::back_inserter(stack));
current_item.m_value.array->clear();
}
else if (current_item.is_object())
{
for (auto&& it : *current_item.m_value.object)
{
stack.push_back(std::move(it.second));
}
current_item.m_value.object->clear();
}
// it's now safe that current_item get destructed
// since it doesn't have any children
}
}
switch (t)
......
single_include/nlohmann/json.hpp
View file @ f883ddd1
......@@ -4480,6 +4480,13 @@ namespace detail
// constructors //
//////////////////
/*
* Note all external_constructor<>::construct functions need to call
* j.m_value.destroy(j.m_type) to avoid a memory leak in case j contains an
* allocated value (e.g., a string). See bug issue
* https://github.com/nlohmann/json/issues/2865 for more information.
*/
template<value_t> struct external_constructor;
template<>
......@@ -4488,6 +4495,7 @@ struct external_constructor<value_t::boolean>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::boolean_t b) noexcept
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::boolean;
j.m_value = b;
j.assert_invariant();
......@@ -4500,6 +4508,7 @@ struct external_constructor<value_t::string>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, const typename BasicJsonType::string_t& s)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::string;
j.m_value = s;
j.assert_invariant();
......@@ -4508,6 +4517,7 @@ struct external_constructor<value_t::string>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::string_t&& s)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::string;
j.m_value = std::move(s);
j.assert_invariant();
......@@ -4518,6 +4528,7 @@ struct external_constructor<value_t::string>
int > = 0 >
static void construct(BasicJsonType& j, const CompatibleStringType& str)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::string;
j.m_value.string = j.template create<typename BasicJsonType::string_t>(str);
j.assert_invariant();
......@@ -4530,6 +4541,7 @@ struct external_constructor<value_t::binary>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, const typename BasicJsonType::binary_t& b)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::binary;
j.m_value = typename BasicJsonType::binary_t(b);
j.assert_invariant();
......@@ -4538,6 +4550,7 @@ struct external_constructor<value_t::binary>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::binary_t&& b)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::binary;
j.m_value = typename BasicJsonType::binary_t(std::move(b));;
j.assert_invariant();
......@@ -4550,6 +4563,7 @@ struct external_constructor<value_t::number_float>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::number_float_t val) noexcept
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::number_float;
j.m_value = val;
j.assert_invariant();
......@@ -4562,6 +4576,7 @@ struct external_constructor<value_t::number_unsigned>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::number_unsigned_t val) noexcept
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::number_unsigned;
j.m_value = val;
j.assert_invariant();
......@@ -4574,6 +4589,7 @@ struct external_constructor<value_t::number_integer>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::number_integer_t val) noexcept
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::number_integer;
j.m_value = val;
j.assert_invariant();
......@@ -4586,6 +4602,7 @@ struct external_constructor<value_t::array>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, const typename BasicJsonType::array_t& arr)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::array;
j.m_value = arr;
j.set_parents();
......@@ -4595,6 +4612,7 @@ struct external_constructor<value_t::array>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::array_t&& arr)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::array;
j.m_value = std::move(arr);
j.set_parents();
......@@ -4608,6 +4626,8 @@ struct external_constructor<value_t::array>
{
using std::begin;
using std::end;
j.m_value.destroy(j.m_type);
j.m_type = value_t::array;
j.m_value.array = j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr));
j.set_parents();
......@@ -4617,6 +4637,7 @@ struct external_constructor<value_t::array>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, const std::vector<bool>& arr)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::array;
j.m_value = value_t::array;
j.m_value.array->reserve(arr.size());
......@@ -4632,6 +4653,7 @@ struct external_constructor<value_t::array>
enable_if_t<std::is_convertible<T, BasicJsonType>::value, int> = 0>
static void construct(BasicJsonType& j, const std::valarray<T>& arr)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::array;
j.m_value = value_t::array;
j.m_value.array->resize(arr.size());
......@@ -4650,6 +4672,7 @@ struct external_constructor<value_t::object>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, const typename BasicJsonType::object_t& obj)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::object;
j.m_value = obj;
j.set_parents();
......@@ -4659,6 +4682,7 @@ struct external_constructor<value_t::object>
template<typename BasicJsonType>
static void construct(BasicJsonType& j, typename BasicJsonType::object_t&& obj)
{
j.m_value.destroy(j.m_type);
j.m_type = value_t::object;
j.m_value = std::move(obj);
j.set_parents();
......@@ -4672,6 +4696,7 @@ struct external_constructor<value_t::object>
using std::begin;
using std::end;
j.m_value.destroy(j.m_type);
j.m_type = value_t::object;
j.m_value.object = j.template create<typename BasicJsonType::object_t>(begin(obj), end(obj));
j.set_parents();
......@@ -18166,53 +18191,55 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
binary = create<binary_t>(std::move(value));
}
void destroy(value_t t) noexcept
void destroy(value_t t)
{
// flatten the current json_value to a heap-allocated stack
std::vector<basic_json> stack;
// move the top-level items to stack
if (t == value_t::array)
{
stack.reserve(array->size());
std::move(array->begin(), array->end(), std::back_inserter(stack));
}
else if (t == value_t::object)
if (t == value_t::array || t == value_t::object)
{
stack.reserve(object->size());
for (auto&& it : *object)
{
stack.push_back(std::move(it.second));
}
}
// flatten the current json_value to a heap-allocated stack
std::vector<basic_json> stack;
while (!stack.empty())
{
// move the last item to local variable to be processed
basic_json current_item(std::move(stack.back()));
stack.pop_back();
// if current_item is array/object, move
// its children to the stack to be processed later
if (current_item.is_array())
// move the top-level items to stack
if (t == value_t::array)
{
std::move(current_item.m_value.array->begin(), current_item.m_value.array->end(),
std::back_inserter(stack));
current_item.m_value.array->clear();
stack.reserve(array->size());
std::move(array->begin(), array->end(), std::back_inserter(stack));
}
else if (current_item.is_object())
else
{
for (auto&& it : *current_item.m_value.object)
stack.reserve(object->size());
for (auto&& it : *object)
{
stack.push_back(std::move(it.second));
}
current_item.m_value.object->clear();
}
// it's now safe that current_item get destructed
// since it doesn't have any children
while (!stack.empty())
{
// move the last item to local variable to be processed
basic_json current_item(std::move(stack.back()));
stack.pop_back();
// if current_item is array/object, move
// its children to the stack to be processed later
if (current_item.is_array())
{
std::move(current_item.m_value.array->begin(), current_item.m_value.array->end(), std::back_inserter(stack));
current_item.m_value.array->clear();
}
else if (current_item.is_object())
{
for (auto&& it : *current_item.m_value.object)
{
stack.push_back(std::move(it.second));
}
current_item.m_value.object->clear();
}
// it's now safe that current_item get destructed
// since it doesn't have any children
}
}
switch (t)
......
test/src/unit-regression2.cpp
View file @ f883ddd1
......@@ -594,4 +594,30 @@ TEST_CASE("regression tests 2")
}
}
}
SECTION("issue #2865 - ASAN detects memory leaks")
{
// the code below is expected to not leak memory
{
nlohmann::json o;
std::string s = "bar";
nlohmann::to_json(o["foo"], s);
nlohmann::json p = o;
// call to_json with a non-null JSON value
nlohmann::to_json(p["foo"], s);
}
{
nlohmann::json o;
std::string s = "bar";
nlohmann::to_json(o["foo"], s);
// call to_json with a non-null JSON value
nlohmann::to_json(o["foo"], s);
}
}
}
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