TestStat: dirNlinkIncludesDot should not necessarily be true #2409
Description
Describe the bug
The number of hard links seems to be defined by the file system. So dirNlinkIncludesDot, which is always true on Linux, is not correct, and causes TestStat to fail sometimes. Instead of hard-coding numbers, it may be best to just start with the existing count on an empty directory, and then check differences when adding/removing files.
To Reproduce
Run tests with a btrfs temporary directory, e.g.,
$ TMPDIR=/path/to/btrfs/directory go test ./internal/sysfs
--- FAIL: TestStat (0.00s)
--- FAIL: TestStat/empty_dir (0.00s)
require.go:331: expected 2, but was 1: linux
.../wazero/internal/sysfs/stat_test.go:46
--- FAIL: TestStat/not_empty_dir (0.00s)
require.go:331: expected 3, but was 1: linux
.../wazero/internal/sysfs/stat_test.go:72
and for example, on a btrfs filesystem an empty directory has 1 Link:
$ mkdir foo
$ stat foo
File: foo
Size: 0 Blocks: 0 IO Block: 4096 directory
Device: 0,43 Inode: 183574674 Links: 1
Access: (0755/drwxr-xr-x) Uid: ( ) Gid: ( )
Context: unconfined_u:object_r:container_file_t:s0
Access: 2025-07-21 05:23:03.222367693 -0400
Modify: 2025-07-21 05:23:03.222367693 -0400
Change: 2025-07-21 05:23:03.222367693 -0400
Birth: 2025-07-21 05:23:03.222367693 -0400
whereas on /tmp, which is tmpfs, an empty directory has 2 Links:
$ mkdir /tmp/foo
$ stat /tmp/foo
File: /tmp/foo
Size: 40 Blocks: 0 IO Block: 4096 directory
Device: 0,40 Inode: 89168 Links: 2
Access: (0755/drwxr-xr-x) Uid: ( ) Gid: ( )
Context: unconfined_u:object_r:user_tmp_t:s0
Access: 2025-07-21 05:24:24.626843648 -0400
Modify: 2025-07-21 05:24:24.626843648 -0400
Change: 2025-07-21 05:24:24.626843648 -0400
Birth: 2025-07-21 05:24:24.626843648 -0400
Expected behavior
Tests should pass.
Environment (please complete the relevant information):
- Go version: go version go1.24.4 linux/amd64
- wazero Version: v1.9.0
- Host architecture: amd64
- Runtime mode: n/a