Prevent stack overflow in json_pointer::flatten - #5517
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Signed-off-by: dajiaohuang <mikewushuwen@outlook.com>
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| std::vector<flatten_task> stack; | ||
| stack.push_back({reference_string, &value}); |
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Should be able to use emplace_back(reference_string, &value);
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Implemented in 46d2b4d: added the C++11-compatible task constructor so the initial frame uses emplace_back(reference_string, &value). The focused C++11/C++20 regression builds pass.
| for (std::size_t i = current.value->m_data.m_value.array->size(); i > 0; --i) | ||
| { | ||
| const auto index = i - 1; | ||
| stack.push_back({detail::concat<string_t>(current.reference_string, '/', std::to_string(index)), |
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Implemented in 46d2b4d: array child frames now use emplace_back with the same traversal and pointer semantics. The focused C++11/C++20 regression builds pass.
| children.reserve(current.value->m_data.m_value.object->size()); | ||
| for (const auto& element : *current.value->m_data.m_value.object) | ||
| { | ||
| children.push_back({detail::concat<string_t>(current.reference_string, '/', detail::escape(element.first)), |
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Implemented in 46d2b4d: object child frames now use emplace_back; the generated single-header smoke build also passes.
| flatten(detail::concat<string_t>(reference_string, '/', std::to_string(i)), | ||
| value.m_data.m_value.array->operator[](i), result); | ||
| // iterate array and use index as a reference string | ||
| for (std::size_t i = current.value->m_data.m_value.array->size(); i > 0; --i) |
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Comment about why this is iterating backwards?
Signed-off-by: dajiaohuang <mikewushuwen@outlook.com>
🔴 Amalgamation check failed! 🔴The source code has not been amalgamated and/or formatted correctly. 📎 A ready-to-apply patch is attached to the failed workflow run as the git apply amalgamation.patchThis does not require installing astyle yourself. |
Signed-off-by: dajiaohuang <mikewushuwen@outlook.com>
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Applied the amalgamation-patch artifact from run 34485452558. Commit fe2f71e updates only include/nlohmann/detail/json_pointer.hpp and single_include/nlohmann/json.hpp to match the generated formatting, and is pushed to fix/5393-iterative-flatten. Validation passed: Release C++11 and C++20 issue #5393 regression selections (1 test, 3 assertions each), Release single_detail_json_pointer build and smoke run, and git diff --check. |
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The GCC C++26 standards jobs exposed a -Werror=noexcept failure for the iterative flatten stack when instantiated with the alternative string type: latten_task's move construction was inferred as potentially throwing. Commit 7121dfd marks that constructor |
Signed-off-by: dajiaohuang <mikewushuwen@outlook.com>
7121dfd to
0eabb21
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Amended the latest fix commit with the repository-required DCO sign-off and force-updated the fork branch. New head: 0eabb21. No source changes beyond the Signed-off-by trailer; the previous C++26 noexcept fix remains intact. |
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Summary
Replace the recursive implementation of
json_pointer::flatten()with an explicit work stack so deeply nested values no longer exhaust the call stack. Existing traversal order and empty-container handling are preserved.This addresses the
flatten()portion of #5393.Validation
test-regression2_cpp11andtest-regression2_cpp20pass, including a 100,000-level nesting regression.test-json_pointer_cpp11andtest-json_pointer_cpp20pass.The generated-header
single_detail_json_pointersmoke executable passes.git diff --checkpasses.The changes are described in detail, both the what and why.
An existing issue is referenced.
The source code is amalgamated.