Limit parser nesting depth instead of crashing with RecursionError#510
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Deeply nested arrays/inline tables and long dotted keys recursed without bound, so crafted input could kill the process (python-poetry#459). Values nested beyond 100 levels and keys with more than 100 dotted fragments now raise ParseError. Dotted-key parsing itself is now iterative; the cap there guards the recursive container machinery downstream.
frostming
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Jun 13, 2026
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Can you also add a bottom line mentioning which agent and model you are using, if any. This will help us evaluate the PR. Thanks! |
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Fixes #459 (picking this up since #468 went stale).
Crafted input could crash the process with a
RecursionErrorvia three unbounded recursion paths: nested arrays, nested inline tables, and dotted keys (every fragment recursed through_parse_key/_parse_bare_key, which the issue didn't mention but has the same effect —'a.'*10000 + 'a = 1'also crashed). Values nested more than 100 levels deep and keys with more than 100 dotted fragments now raiseParseErrorwith position info;MAX_NESTING_DEPTHis a class attribute so subclasses can override it.Dotted-key parsing is now a loop instead of recursion (the chain is linear, and
concatflattening is associative so left-to-right building produces identical keys); the cap is still needed there because each fragment creates a level of nested containers and operations likeContainer.parsing()recurse over that tree. Documents at exactly the limit still parse and round-trip — covered in the tests, which all fail withRecursionErroron master.