OpenSystemsDevelopment / qpdf

…ys with `std::string`, and simplify related password handling logic.

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

…, 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.

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.

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

Refactored several classes to use C++11 `final` specifiers for inheritance restrictions and added default member initializations. These changes enhance code clarity, improve safety, and ensure modern coding practices.

Replaced std::shared_ptr<char> with std::string for passwords in QPDFJob. This simplifies memory management and aligns the implementation with modern C++ standards, improving code readability and maintainability.

Replaced shared pointer usage with a plain std::string for passwords in PageSpec to simplify code and enhance readability. Updated relevant logic and function calls to align with this change, removing unnecessary shared pointer management. Updated TODO to reflect completion of this modernization step.

Replaced `std::shared_ptr<char>` with `std::string` for password fields to simplify memory management and improve clarity. Updated relevant method implementations and function calls accordingly. This change ensures more straightforward and safer password handling throughout the codebase.

Replaced raw shared pointers with std::string for `infilename` to improve simplicity and readability. Added a boolean `empty_input` flag to explicitly track empty input cases. Adjusted related logic and function calls accordingly for consistency.

Replaced shared_ptr<char> with std::string for `outfilename` in QPDFJob, simplifying its usage and reducing unnecessary memory management overhead. Updated related conditional checks and logic to align with the updated type. These changes improve code readability and maintainability.

Converted multiple occurrences of `count()` to `contains()` throughout the codebase where the goal was to check key existence in containers. This improves code readability and aligns with modern C++ practices, particularly with C++20, making the intent more explicit and potentially aiding performance.

When validating the pages tree after xref recovery do not tree dictionaries
as page objects if more than 2 of the following are true:

- the dictionary is direct
- the /Type entry is missing or is not /Page
- the dictionary does not contain a valid /Parent entry
- the dictionary does not contain or inherit a valid /MediaBox
- the dictionary does not contain or inherit a /Resources dictionary

Such dictionaries are very unlikely to be page objects and trying to
process them may cause excessive run time and memory usage.

Refine xref table reconstruction

During xref table reconstruction ignore uncompressed object entries found
in xref streams. The xref table gets populated with entries for the
objects actually found in the file. The entries for uncompressed object in
xref streams are redundant and potentially incorrect.

Return the display value if the choices entry is an array of strings rather
than a single string.

Test file is need-appearances.pdf modified to contain one array entry.

Thanks to github user @cdosborn for the basic enhancement.

Only top-level XMP metadata is supposed to be left unencrypted. All
other metadata is not treated specially.

Internally use -1 to represent a missing offset and provide a constructor
overload that allows 0 as a valid offset.

In QPDF::damagedPDF use the new overload.

... to remove the /Root /StructTreeRoot and /MarkInfo entries.

... and use it in QPDFWriter and QPDF::generateHintStream.