fix: escape parser error messages

[neuriv]

Description

Fixes #1436.

Escape parser error messages before inserting them into the JSON exception payload. Handle quotes, backslashes and control bytes in one pass while preserving ordinary text and UTF-8, so Python can report the original validation error.

Testing

ubuntu 22.04, 1xa100, 12.9.86, pythn 3.14

import json
from pathlib import Path
import tempfile

from cuopt.linear_programming import Read
from cuopt.linear_programming.io.utilities import InputValidationError

with tempfile.TemporaryDirectory() as directory:
    names = ['missing.mps', 'missing "C:\\data" café' + ''.join(map(chr, range(1, 32))) + '.mps']
    for name in names:
        path = str(Path(directory) / name)
        try:
            Read(path)
        except InputValidationError as error:
            assert path in str(error), repr(str(error))
            print(json.dumps({'exception': type(error).__name__, 'message': str(error)}), flush=True)
        else:
            raise AssertionError('missing input did not raise InputValidationError')

Baseline raised JSONDecodeError for the special-character path. The fixed build raised InputValidationError and preserved the complete path, including quotes, backslashes, UTF-8 and all non-NUL control bytes.

export RAPIDS_DATASET_ROOT_DIR="$PWD/datasets"
python -m pytest -q -r a \
  python/cuopt/cuopt/tests/linear_programming/test_parser.py
pre-commit run --all-files

unit test

all passed.

#!/usr/bin/env bash
set -euo pipefail
repo=$(cd "${1:?provide the cuopt checkout}" && pwd)
gtest=$(cd "${2:?provide the googletest checkout}" && pwd)
shift 2
test_dir=$(mktemp -d)
trap 'rm -rf "$test_dir"' EXIT
cat > "$test_dir/unit_test.cpp" <<'CPP'
#include <io/utilities/error.hpp>
#include <gmock/gmock.h>
#include <gtest/gtest.h>

namespace cuopt::mathematical_optimization::io {

TEST(mps_parser, error_message_json_escaping)
{
  const char* message = "file \"C:\\data\"\n\r\t\b\f\x01\x1f";
  EXPECT_THAT(
    [=] { mps_parser_throw(error_type_t::ValidationError, message); },
    ::testing::ThrowsMessage<std::logic_error>(
      R"({"MPS_PARSER_ERROR_TYPE": "ValidationError", "msg": "file \"C:\\data\"\u000a\u000d\u0009\u0008\u000c\u0001\u001f"})"));
}

TEST(mps_parser, error_message_preserves_text)
{
  EXPECT_THAT([] { mps_parser_throw(error_type_t::RuntimeError, "plain / café"); },
              ::testing::ThrowsMessage<std::logic_error>(
                R"({"MPS_PARSER_ERROR_TYPE": "RuntimeError", "msg": "plain / café"})"));
  EXPECT_THAT([] { mps_parser_throw(error_type_t::OutOfMemoryError, ""); },
              ::testing::ThrowsMessage<std::logic_error>(
                R"({"MPS_PARSER_ERROR_TYPE": "OutOfMemoryError", "msg": ""})"));
}

}
CPP
"${CXX:-c++}" -std=c++20 -g -O1 -pthread -fsanitize=address,undefined "$@" \
  -I"$repo/cpp/src" \
  -I"$gtest/googletest/include" -I"$gtest/googletest" \
  -I"$gtest/googlemock/include" -I"$gtest/googlemock" \
  "$test_dir/unit_test.cpp" "$gtest/googletest/src/gtest-all.cc" \
  "$gtest/googletest/src/gtest_main.cc" "$gtest/googlemock/src/gmock-all.cc" \
  -o "$test_dir/unit-test"
"$test_dir/unit-test"

cc @yuwenchen95 @aliceb-nv

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• cpp/src/io/utilities/error.hpp

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📝 Walkthrough

Walkthrough

The error utility adds json_escape(std::string_view). mps_parser_throw and mps_parser_no_except now use escaped messages when constructing JSON parser error payloads.

Changes

Parser error JSON encoding

Layer / File(s)	Summary
Escape parser messages cpp/src/io/utilities/error.hpp	Adds string-view support and json_escape. The helper escapes control characters, quotes, and backslashes. mps_parser_throw uses the escaped message, and mps_parser_no_except delegates error construction to it.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Medium

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	For #1436, json_escape(std::string_view) escapes quotes and backslashes and encodes all control bytes as \\u00XX. mps_parser_throw() applies the helper before inserting msg into the JSON payloa…
Out of Scope Changes check	✅ Passed	The whole-PR diff changes only cpp/src/io/utilities/error.hpp. The helper, its use in mps_parser_throw(), and the mps_parser_no_except() delegation support the escaping requirement in #1436. No …
Title check	✅ Passed	The title clearly and concisely describes the main change: escaping parser error messages.
Description check	✅ Passed	The description directly explains the escaping fix, affected characters, objectives, and testing results.

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Actionable comments posted: 1

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Inline comments:
In `@cpp/src/io/utilities/error.hpp`:
- Around line 39-63: Update the mps_parser_no_except macro to delegate to
mps_parser_throw using error_type and msg.c_str(), removing its duplicate JSON
payload construction so raw messages receive json_escape handling.

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[nguidotti]

/ok to test 3fceb25

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CI Test Summary

✅ All 32 test job(s) passed.