Support for writing and reading manifest data from simple PDFs (without incremental updates or signatures)

[dyro]

Changes in this pull request

This PR introduces the pdf_utils::Pdf struct and the pdf_utils::C2paPdf trait, public (to the crate), lopdf abstractions with functionality to read and write manifest data from PDFs. This code works against wasm and non-wasm targets.

I intend to add read support next, then round out the work with incremental update support. I opened this PR against origin/pdf instead of main as I want to get this in front of folks before getting to far and this work doesn't support reading manifests or incremental PDF updates.

Checklist

• This PR represents a single feature, fix, or change.
• All applicable changes have been documented.
• Any TO DO items (or similar) have been entered as GitHub issues and the link to that issue has been included in a comment.

[codecov-commenter]

Codecov Report

Patch coverage: 94.73% and project coverage change: +0.20% 🎉

Comparison is base (760009c) 78.73% compared to head (1e97fbb) 78.94%.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #249      +/-   ##
==========================================
+ Coverage   78.73%   78.94%   +0.20%     
==========================================
  Files          76       77       +1     
  Lines       22465    22764     +299     
==========================================
+ Hits        17687    17970     +283     
- Misses       4778     4794      +16     

Files Changed	Coverage Δ
sdk/src/utils/pdf_utils.rs	94.68% <94.68%> (ø)
sdk/src/claim.rs	83.15% <100.00%> (-0.03%)	⬇️

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[scouten-adobe]

One tiny documentation nit and a couple of non-blocker questions to consider.

I'd like @mauricefisher64 to review this since he knows PDF better than I do, but otherwise, this looks really solid. Easy code to follow!

[mauricefisher64]

👍

[dyro]

hey @scouten-adobe & @mauricefisher64 : I believe I've addressed all of your feedback. Please take a look again when you have a moment!

[scouten-adobe]

Please either explain the Vec of slices or remove the abstraction. Otherwise 👍

[mauricefisher64]

👍

[mauricefisher64]

Not holding up this PR but does the lopdf handle PDF permissions and passwords?

[dyro]

@mauricefisher64: Yes, lopdf has support for passwords. After creating a Document instance, you call the its decrypt method with a password. Wasn't sure how to integrate that into the c2pa-rs public API