We need to shorten the timeout to bound effectively for
computation size. This protects against "too big" repos.
This also protects to some extent against too long lines
if kept to very low values (basically so that grep cannot run out
of memory beforehand).
Docs-PR: forgejo/docs#812
- The parser of `git grep`'s output uses `bufio.Scanner`, which is a good
choice overall, however it does have a limit that's usually not noticed,
it will not read more than `64 * 1024` bytes at once which can be hit in
practical scenarios.
- Use `bufio.Reader` instead which doesn't have this limitation, but is
a bit harder to work with as it's a more lower level primitive.
- Adds unit test.
- Resolves https://codeberg.org/forgejo/forgejo/issues/3149
By using git's ability, end users (especially small instance users) do
not need to enable the indexer, they could also benefit from the code
searching feature.
Fix#29996


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Co-authored-by: silverwind <me@silverwind.io>