OpenSystemsDevelopment / qpdf

Also, when recovering trailer from xref streams, pick the last valid
trailer encountered rather than the first.

Change first xref stream dictionary to point to an invalid root in order
to detect failure to recover the last valid trailer.

In FUTURE, treat uninitialized object handles as null

Adjust fuzzer Pl_Flate memory limits

Fixes fuzz issue 71689.

Change the return type to a std::pair<bool, QPDFObjectHandle> in order to
allow a default constructed object handle (which is currently returned to
indicate failure) to become a valid object.

Fix handling of hybrid reference files in QPDF::read_xrefTable

Fix #1242

Fix QPDF::recoverStreamLength

Tidy QPDF_Stream

Replace some std::shared_ptr parameters with reference parameters

Ensure QPDF m->all_pages and invalid_page_found are reset if
getAllPagesInternal throws an exception.

Fixes fuzz case 71624.

Refactor ObjTable

1. Make class final
2. Pass og parameter by value
3. Properly initialize qpdf and og

Also, tweak QPDF::replaceObject to allow stream replacement without
violating the requirement that streams must always be indirect objects.

Also, remove QPDF::reserveStream as it does not do what the name implies
and having this as a separate methods does not aid code readability.

Split qpdf_fuzzer into six separate fuzzers

Given that the PDF spec requires the xref table to contain entries for all
object ids <= the maximum id present in a PDF document, max_size is a
qpdf implementation limitation for legitimate object ids.

Refactor QPDFObjectHandle::getTypeName

In qpdf_fuzzer and dct_fuzzer add a scan limit for Pl_DCT

In QPDF::readObjectAtOffset fail early on 'expect n n obj'

Refactor Pl_QPDFTokenizer

Ensure the the recovered stream end is not part of a different object.

Test file is bad24.pdf with stream 4 'endstream' corrupted.