Escape NUL bytes in white diff admin text. - #1726
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NUL is valid UTF-8, so decoding with backslashreplace keeps it as-is. PostgreSQL rejects NUL in text columns, so writing the evaluation fails and EvaluationService retries it forever, leaving the testcase unscored. Escape it as \x00, consistent with how backslashreplace renders invalid bytes, so the admin can still see the difference.
veluca93
approved these changes
Oct 5, 2026
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NUL is valid UTF-8, so
backslashreplaceleaves it as-is in the white diffadmin_text. PostgreSQL rejects NUL in text columns, so writing theevaluation fails, and EvaluationService retries it forever, leaving the
testcase unscored. Triggered by a contestant printing a NUL byte on a
mismatching line (e.g. uninitialized memory) in a Batch task with the
built-in diff.
The fix escapes NUL as
\x00instead of stripping it, so the differencestays visible.
Regression from b98e44b, not in any release. Similar to #888. Hit this in
production during an exam.