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Replace memcpy with std::copy to avoid undefined behaviour when buffers overlap. #37

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merged 2 commits into from
Nov 27, 2023
Merged

Replace memcpy with std::copy to avoid undefined behaviour when buffers overlap. #37

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e60b845
Fix memcpy
LinZhihao-723 Nov 26, 2023
ff7a6b6
Accomandate code review comments
LinZhihao-723 Nov 27, 2023
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38 changes: 23 additions & 15 deletions src/clp_ffi_py/ir/native/PyDecoderBuffer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -32,8 +32,7 @@ auto PyDecoderBuffer_init(PyDecoderBuffer* self, PyObject* args, PyObject* keywo
static char* keyword_table[]{
static_cast<char*>(keyword_input_stream),
static_cast<char*>(keyword_initial_buffer_capacity),
nullptr
};
nullptr};

// If the argument parsing fails, `self` will be deallocated. We must reset
// all pointers to nullptr in advance, otherwise the deallocator might
Expand All @@ -55,8 +54,8 @@ auto PyDecoderBuffer_init(PyDecoderBuffer* self, PyObject* args, PyObject* keywo
return -1;
}

PyObjectPtr<PyObject> const readinto_method_obj{PyObject_GetAttrString(input_stream, "readinto")
};
PyObjectPtr<PyObject> const readinto_method_obj{
PyObject_GetAttrString(input_stream, "readinto")};
auto* readinto_method{readinto_method_obj.get()};
if (nullptr == readinto_method) {
return -1;
Expand Down Expand Up @@ -154,8 +153,7 @@ PyMethodDef PyDecoderBuffer_method_table[]{
METH_O,
static_cast<char const*>(cPyDecoderBufferTestStreamingDoc)},

{nullptr}
};
{nullptr}};

/**
* Declaration of Python buffer protocol.
Expand Down Expand Up @@ -190,8 +188,7 @@ PyType_Slot PyDecoderBuffer_slots[]{
{Py_tp_init, reinterpret_cast<void*>(PyDecoderBuffer_init)},
{Py_tp_methods, static_cast<void*>(PyDecoderBuffer_method_table)},
{Py_tp_doc, const_cast<void*>(static_cast<void const*>(cPyDecoderBufferDoc))},
{0, nullptr}
};
{0, nullptr}};
// NOLINTEND(cppcoreguidelines-avoid-c-arrays, cppcoreguidelines-pro-type-*-cast)

/**
Expand All @@ -202,8 +199,7 @@ PyType_Spec PyDecoderBuffer_type_spec{
sizeof(PyDecoderBuffer),
0,
Py_TPFLAGS_DEFAULT,
static_cast<PyType_Slot*>(PyDecoderBuffer_slots)
};
static_cast<PyType_Slot*>(PyDecoderBuffer_slots)};

// NOLINTNEXTLINE(cppcoreguidelines-avoid-c-arrays)
PyDoc_STRVAR(
Expand All @@ -227,8 +223,9 @@ auto PyDecoderBuffer::init(PyObject* input_stream, Py_ssize_t buf_capacity) -> b
}

auto PyDecoderBuffer::populate_read_buffer(Py_ssize_t& num_bytes_read) -> bool {
auto const num_unconsumed_bytes{get_num_unconsumed_bytes()};
auto const unconsumed_bytes{get_unconsumed_bytes()};
auto const unconsumed_bytes_in_curr_read_buffer{get_unconsumed_bytes()};
auto const num_unconsumed_bytes{
static_cast<Py_ssize_t>(unconsumed_bytes_in_curr_read_buffer.size())};
auto const buffer_capacity{static_cast<Py_ssize_t>(m_read_buffer.size())};

if (num_unconsumed_bytes > (buffer_capacity / 2)) {
Expand All @@ -240,12 +237,20 @@ auto PyDecoderBuffer::populate_read_buffer(Py_ssize_t& num_bytes_read) -> bool {
return false;
}
auto new_read_buffer{gsl::span<int8_t>(new_buf, new_capacity)};
memcpy(new_read_buffer.data(), unconsumed_bytes.data(), num_unconsumed_bytes);
std::copy(
unconsumed_bytes_in_curr_read_buffer.begin(),
unconsumed_bytes_in_curr_read_buffer.end(),
new_read_buffer.begin()
);
PyMem_Free(m_read_buffer_mem_owner);
m_read_buffer_mem_owner = new_buf;
m_read_buffer = new_read_buffer;
} else if (0 < num_unconsumed_bytes) {
memcpy(m_read_buffer.data(), unconsumed_bytes.data(), num_unconsumed_bytes);
std::copy(
unconsumed_bytes_in_curr_read_buffer.begin(),
unconsumed_bytes_in_curr_read_buffer.end(),
m_read_buffer.begin()
);
}
m_num_current_bytes_consumed = 0;
m_buffer_size = num_unconsumed_bytes;
Expand Down Expand Up @@ -327,7 +332,10 @@ auto PyDecoderBuffer::test_streaming(uint32_t seed) -> PyObject* {
std::vector<uint8_t> read_bytes;
bool reach_istream_end{false};
while (false == reach_istream_end) {
std::uniform_int_distribution<Py_ssize_t> distribution(1, m_read_buffer.size());
std::uniform_int_distribution<Py_ssize_t> distribution(
1,
static_cast<Py_ssize_t>(m_read_buffer.size())
);
auto num_bytes_to_read{distribution(rand_generator)};
if (get_num_unconsumed_bytes() < num_bytes_to_read) {
Py_ssize_t num_bytes_read_from_istream{0};
Expand Down