ROB: Rebuild xref table if one entry is invalid

[pubpub-zz]

closes #2516

cope with cases where the xref entries do not point to valid headers

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.48%. Comparing base (c4641d1) to head (553165c).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2528      +/-   ##
==========================================
- Coverage   94.52%   94.48%   -0.04%     
==========================================
  Files          49       49              
  Lines        8178     8181       +3     
  Branches     1659     1660       +1     
==========================================
  Hits         7730     7730              
- Misses        277      280       +3     
  Partials      171      171              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[stefan6419846]

I am going to wait with the review of these changes until #2526 is merged as #2528 already incorporates the changes of #2526.

[pubpub-zz]

test ,file:
iss2516.pdf

[stefan6419846]

It seems like this small change has quite some impact on the coverage as

pypdf/pypdf/_reader.py

Lines 1277 to 1301 in c4641d1

	except Exception:
	if hasattr(self.stream, "getbuffer"):
	buf = bytes(self.stream.getbuffer())
	else:
	p = self.stream.tell()
	self.stream.seek(0, 0)
	buf = self.stream.read(-1)
	self.stream.seek(p, 0)
	m = re.search(
	rf"\s{indirect_reference.idnum}\s+{indirect_reference.generation}\s+obj".encode(),
	buf,
	)
	if m is not None:
	logger_warning(
	f"Object ID {indirect_reference.idnum},{indirect_reference.generation} ref repaired",
	__name__,
	)
	self.xref[indirect_reference.generation][
	indirect_reference.idnum
	] = (m.start(0) + 1)
	self.stream.seek(m.start(0) + 1)
	idnum, generation = self.read_object_header(self.stream)
	else:
	idnum = -1 # exception will be raised below
	if idnum != indirect_reference.idnum and self.xref_index:

is not being covered by the tests any more. Is there something we can do about this without ignoring it or excluding the error handling from the coverage?

[pubpub-zz]

This is the best I can propose