[RFC] resolve a recursion bug in ObjectHash#deref! #195
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This single page PDF has a Form XObject in its Resources dict. The Form XObject has its own Resources dict, which has an XObject pointing to itself. Nested XObjects are fine, but not recursive ones. This is a simpler file that demonstrates an issue originally found in the PDF provided at [1] [1] #94 (comment)
* deref! was added in 9c520b6 and attempts to return a deep object graph that contains no PDF::Reader::Reference objects and can be walked without risk of needing to refer back to the associated ObjectHash instance * This change resolves a recursion bug that can occur in real world files, but it also weakens the guarantee that the returned object graph can be used without the ObjectHash. It's possible that the returned graph will contain a PDF::Reader::Stream instance that contains some PDF::Reader::Reference objects. * I'm not yet convinced that this is the right solution - but the build is green and it's an option open to us.
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I decided to merge an alternate solution - see #198 |
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This removes special handling of Stream objects from
ObjectHash#deref!.deref!was added in 9c520b6 and attempts to return a deep object graph that contains noPDF::Reader::Referenceobjects and can be walked without risk of needing to refer back to the associatedObjectHashinstance.This change resolves a recursion bug that can occur in real world files, but it also weakens the guarantee that the returned object graph can be used without the
ObjectHash. It's possible that the returned graph will contain aPDF::Reader::Streaminstance that contains somePDF::Reader::Referenceobjects.I'm not yet convinced that this is the right solution - but the build is green and it's an option open to us. This would be a breaking change to a public API, and although our build is green it may impact users.