find_repo function can enter an infinite loop

[smithx]

Reproduction steps

call

git_buf out{};
git_repository_discover(&out, "\\\\?\\Volume{20693787-e361-42da-97c9-f66d2468f001}\\EFI\\Boot", 0, NULL);

Expected behavior

function return

Actual behavior

function doesn't return
subcall find_repo never break from loop

Version of libgit2 (release number or SHA1)

'main' branch 8164b48

Operating system(s) tested

Windows 10 Pro 22H2

[ethomson]

I've struggled here to reproduce this — I don't seem to have this problem on my Windows machine (using my volume GUID). I'll keep trying, but if there's any additional data to reproduce this, that would be helpful.

[smithx]

You don't need Windows machine to reproduce it. Just check the unit test from PR #6525

test function name is 'test_repo_discover__discovery_starting_at_unmounted_win_root_causes_no_hang'

[ethomson]

That test runs successfully on all my machines (macOS, Windows 11) without any changes to the find repo function. Does it still fail for you without any changes?

[smithx]

You are absolutely right, the test will not fail with some 'uuid-volume' path. We need such a 'uuid-volume' path that will successfully pass here: git_fs_path_prettify(&path, start_path, NULL).
If we go into the loop with path.ptr points to something like this \\\\?\\Volume{11111111-2222-3333-4444-555555555555}\\EFI\\Boot, we will never get out again