OpenSystemsDevelopment / qpdf

…implify padding logic, and streamline password handling across methods.

…nline previously separate method, and streamline data encoding logic.

…ased logic in `setEncryptionMinimumVersion`, and reduce redundancy across `QPDFWriter` methods.

…ption dictionary generation, and reduce redundancy in encryption handling logic.

… encryption handling, and reduce redundancy across methods.

…`, simplify method signatures, and centralize logic in `QPDF::EncryptionData` for improved maintainability.

…ng in method parameters, and simplify encryption logic for improved maintainability and reduced redundancy.

…uce redundancy, improve maintainability, and streamline parameter handling.

…ling, and improve maintainability.

…Perms_value_V5` methods; inline their logic into `setV5EncryptionParameters` to simplify encryption data processing.

…dom_string`, improve readability of salts and keys handling, and streamline `compute_Perms_value_V5_clear` logic by returning strings directly.

…std::bitset`, reorganizing related methods, and simplifying access to improve clarity and maintainability.

…irectly access encryption parameters for improved clarity and maintainability.

…, transition `interpretCF` to a class method, and eliminate redundant parameter passing for improved clarity and maintainability.

…rs::initialize` and replacing shared pointers with references for improved clarity and maintainability.

…t parameter passing, and improve maintainability. Change static functions and QPDF methods to EncryptionData methods.

Miscellaneous code modernisation

Streamlined method definitions, replaced explicit loop counters with range-based loops, and added `final` specifier to class and methods to ensure overriding restrictions. Simplified constructor and member variable initialization.

…ssing to simplify buffer handling

…cess for consistency and readability.

Refactor object reading logic in `QPDF` for clarity and improved main…

Simplify `readObjectAtOffset` by splitting responsibilities into separate functions: `read_object_start` and a streamlined `readObjectAtOffset`. Remove redundant parameters and improve code readability, ensuring better modularity for object reading operations.

Extend xref reconstruction sanity checks

After xref reconstruction treat the input file as suspect and apply sanity checks to all subsequent object reads.

Remove `in_xref_reconstruction` flag and update references to use `reconstructed_xref` for simplified state management during xref processing. Adjust warnings for invalid dictionary keys in test output.

Refactor `Pl_DCT` buffer management to use `std::string` and simplify…

…n/decompression logic. Remove redundant `Buffer` class dependency.

Apply sanity checks on dangling reference object ids encountered before

the xref table has been loaded

Improve sanity checks and error handling in `QPDFParser`

Enhanced handling of unexpected tokens during xref table reconstruction. Adjusted logic for invalid tokens, ensuring better robustness during PDF parsing of corrupt PDF files.

Enhance error handling for unexpected tokens during sanity checks

Implemented stricter sanity checks to  handle unexpected tokens like array/dictionary close and endobj/endstream more effectively. Improved warning messages and handling of corrupt objects to enhance PDF parsing robustness.

Apply sanity checks during xref stream parsing

Detect corrupt xref streams early to avoid excessive runtime and memory usage.

Fix apparent typo for zopfli enablement

Refactor ADBE handling logic in QPDFWriter.

Reorganized and cleaned up the logic for managing ADBE entries in the /Extensions dictionary, improving clarity and maintainability. Adjusted object shallow copying to avoid unnecessary copying.

Fix startxref recovery

Backup and restore the xref table during attempted startxref recovery to avoid corrupt states. Added a guard condition to handle invalid xref entries types, preventing processing of unsupported cases. These changes improve robustness during PDF parsing and recovery.