OpenSystemsDevelopment / qpdf

Try a  limit of 50MB. For very large limits processing time before
damage is encountered may exceed oss-fuzz limits.
Add further test cases.

If reconstruct_xref generates more than 1000 warnings give up because the
file is so severely damaged that there is very little point continuing.

Reject non-dictionary Page and Pages objects.

Also add additional qpdf_fuzzer test cases.

If throw_on_corrupt is set, use a custom implementation of libjeg's
emit_message procedure to throw an exception when the first corrupt data
warning is encountered.

Check that xref table is not empty after recovery. Empty xref tables
disable other sanity checks.

Fixes oss-fuzz 70055

Previous test case was lost in #1221. Test file was created from
object-stream.pdf by adding a reference to itself into object stream 1 0.

As a rule, we should avoid conditional compilation is it always causes
code paths that are sometimes not even seen lexically by the compiler.
Also, we want the actual code being fuzzed to be as close as possible
to the real code. Conditional compilation is suitable to handle
underlying system differences.

Instead, favor configuration using callbacks or other methods that can
be triggered in the places where they need to be exercised.

Invalid entries are created when objects in the stream do not have
an existing xref entry.

Ensure objects with impossibly large ids are ignored.

Add extra fuzz test case and amend memory limit for Pl_DCT.

Refine #1225

Also, add diagnostic messages in qpdf_fuzzer and additional fuzz test case.

Fix #1170

In PL_DCT add option to limit the size of uncompressed corrupt data

In QPDF::read_xrefEntry add buffer overflow test for first eol character.
Overlong f1 or f2 entries consisting only of zeros could cause a buffer
overflow.

Add fuzz testcase 69913.

Refine handling of severely damaged files

Also, apply limit in dct_fuzzer

Also add new fuzz test case.

Refactor QPDF::parse_xrefEntry

QPDF::processXRefStream

A file that has Widget annotations that can't be mapped back to form
fields would crash qpdf json.

Change the processed Index array to a vector of <first object, number of
entries> pairs.

Add closure damaged to create damagedPDF exceptions.

Tune processing of subsections.

Tune pointer arithmetic.

Apply temporary fix to deal with fuzz case 68915.

(Error is an integer overflow which would immediately cause a runtime error
as a result of a call to QInitCQIntC::to_size.)