add last1K limit to readNextEndLine

[jonnythebard]

I've been processing over 50k of pdf file with PyPDF2 for last several weeks and found it isn't filtering some malformed pdf file. The problem with malformed pdf file was that it had %%EOF marker at the beginning followed by 30m bytes of b'\x00'. Current version of PyPDF2 tries to travel all the way though 30m bytes of b'\x00' and find %%EOF. Since %%EOF marker should appear in last 1k of the file i thought it would make sense to add last1K limit to readNextEndLine function. i applied this to my application and it works fine.

[elyssonmr]

Looking forward for this Pull request to be accepted

[MartinThoma]

Have you seen #642 ? What do you think about it?

[jonnythebard]

@MartinThoma Yes it looks much better than mine because my commit replaces a condition in the if phrase instead of adding one. I didn't notice my mistake. Glad that someone is finally being aware of this issue though 😂

[codecov-commenter]

Codecov Report

Merging #439 (8c2cc97) into main (d5a5eea) will not change coverage.
The diff coverage is 80.00%.

@@           Coverage Diff           @@
##             main     #439   +/-   ##
=======================================
  Coverage   70.59%   70.59%           
=======================================
  Files          10       10           
  Lines        3425     3425           
  Branches      798      798           
=======================================
  Hits         2418     2418           
  Misses        763      763           
  Partials      244      244           

Impacted Files	Coverage Δ
PyPDF2/pdf.py	72.42% <80.00%> (ø)

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