This issue was initially reported by @michaelgranzow-avi on #2296.
@airween made an initial attempt to provide a fixed at #2107; As a
consequence of the pull request review - provided by @victorhora,
@zimmerle, and @michaelgranzow-avi - @airween made a second attempt
at #2297. After reviewing by @martinhsv, @zimmerle, I have absorbed
the essential pieces from @airween patch into this one.
This patch differs from @airween's because @airween's patches were
partially working: Key exclusions with regex weren't covered, same
for anchored variables (e.g. ARGS). During the review, I have
highlighted the importance of having elementary test cases. A simple
test case on ARGS could spot the issue. Since that is an important
fix, I don't want to hold this for one more review cycle; therefore,
I am committing the fix myself.
Thank you all involved in the solution of this very own issue.
This commit fixes quite a few odd things in regex code:
* Lack of encapsulation.
* Non-method functions for matching without retrieving all groups.
* Regex class being copyable without proper copy-constructor (potential UAF
and double free due to pointer members m_pc and m_pce).
* Redundant SMatch::m_length, which always equals to match.size() anyway.
* Weird SMatch::size_ member which is initialized only by one of the three matching
functions, and equals to the return value of that function anyways.
* Several places in code having std::string value instead of reference.
