Cap parser nesting depth to prevent stack overflow#4
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parseArray/parseDict recursed without limit, so deeply nested [[[...]]] or <<...>> in a hostile PDF could overflow the stack -- a fatal, unrecoverable crash. Cap nesting at maxParseDepth (1000) and return an error past it; real PDFs nest only a few levels. Tests: deeply nested array and dict are rejected; moderate nesting still resolves.
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Problem
parseArray/parseDictrecurse with no depth limit. A hostile PDF with deeply nested[[[…]]]or<<…>>drives the recursive-descent parser into a stack overflow — a fatal, unrecoverable crash (it isn't catchable byrecover). Reachable fromOpenand from any object resolution.Fix
Cap nesting at
maxParseDepth(1000) in bothparseArrayandparseDict, returning an error past it. Real PDFs nest only a handful of levels; 1000 is far above legitimate use and far below a stack overflow.Tests
TestDeeplyNestedRejected(array + dict subtests) — input nested well past the cap returns an error instead of crashing.TestModeratelyNestedArrayResolves— moderate nesting (100) still resolves to anArray, so the cap doesn't break legitimate input.Test depths sit above the cap but below an actual stack overflow, so a regression surfaces as a clean failure. Full suite +
go vetpass; gofmt-clean.