tree 8ee94a40b5dd461ff31ae001697cd6b3df545570
parent dd0aa811dd329f5040c70f7aac514b3757eb2453
author Patrick Steinhardt <ps@pks.im> 1495450424 +0200
committer Patrick Steinhardt <ps@pks.im> 1496734433 +0200

varint: fix computation for remaining buffer space

When encoding varints to a buffer, we want to remain sure that the
required buffer space does not exceed what is actually available. Our
current check does not do the right thing, though, in that it does not
honor that our `pos` variable counts the position down instead of up. As
such, we will require too much memory for small varints and not enough
memory for big varints.

Fix the issue by correctly calculating the required size as
`(sizeof(varint) - pos)`. Add a test which failed before.