t.Fatal(err)
	}

	// 4) Streaming bitrot check on corrupted file
	filePath := pathJoin(storage.String(), volName, fileName)
	f, err := os.OpenFile(filePath, os.O_WRONLY|os.O_SYNC, 0o644)
	if err != nil {
		t.Fatal(err)
	}
	// Replace first 256 with 'a'.
	if _, err := f.WriteString(strings.Repeat("a", 256)); err != nil {
		t.Fatal(err)
	}

pkg os, func Lstat(string) (fs.FileInfo, error)
pkg os, func Mkdir(string, fs.FileMode) error
pkg os, func MkdirAll(string, fs.FileMode) error
pkg os, func MkdirTemp(string, string) (string, error)
pkg os, func OpenFile(string, int, fs.FileMode) (*File, error)
pkg os, func ReadDir(string) ([]fs.DirEntry, error)
pkg os, func ReadFile(string) ([]uint8, error)
pkg os, func SameFile(fs.FileInfo, fs.FileInfo) bool

pkg go/build, type Context struct, IsAbsPath func(string) bool
pkg go/build, type Context struct, IsDir func(string) bool
pkg go/build, type Context struct, JoinPath func(...string) string
pkg go/build, type Context struct, OpenFile func(string) (io.ReadCloser, error)
pkg go/build, type Context struct, ReadDir func(string) ([]os.FileInfo, error)
pkg go/build, type Context struct, SplitPathList func(string) []string