[0.x] Fix memory leaks of string buffers

[jhawthorn]

In a few places we were passing malloc'd memory to rb_str_new (and variants) and returning the resulting VALUE without freeing the passed C string buffer.

One of these leaks was introduced by #171 (we can see that some calls to free were lost in the rewrite), but others seem to predate that.

After this change I'm able to run ASAN_OPTIONS="detect_leaks=1" RUBY_FREE_AT_EXIT=1 bundle exec rake with an ASAN-built Ruby without errors.

require "commonmarker"
10.times do
  100.times do
    CommonMarker.render_html("hello, world\n"*10000)
  end
  puts `ps -orss= -p #$$`
end

❯ bundle exec ruby test.rb
74736
112112
112112
128496
172016
203120
203120
203120
241392
266480

cc @anticomputer @phillmv

[kivikakk]

LGTM :) Thank you!

[gjtorikian]

After two years of managing this fork I think it’s fair to ask: can y’all please move to the 1.x/Rust-backed version?

[gjtorikian]

@jhawthorn Please, don’t interpret my comment as hostility. I literally had a panic attack after the PR merged because I wasn’t sure if the C-backed gem was still auto deploying or not; it’s been a while since the last cut and I didn’t know if I would get a ping about the gem not being released.

I would like to remove the part of my brain that worries about this old gem being a part of your infrastructure. Let me know if there’s anything I can do to help update.