try some more tsting

internal/fswatcher/watcher.go

@@ -0,0 +1,44 @@
+package fswatcher
+
+import (
+	"fmt"
+	"io/ioutil"
+	"strconv"
+	"strings"
+
+	"golang.org/x/sys/unix"
+)
+
+const events = unix.IN_ALL_EVENTS
+const MaximumWatchersFile = "/proc/sys/fs/inotify/max_user_watches"
+
+type watcher struct {
+	wd  int
+	dir string
+}
+
+func newWatcher(fd int, dir string) (*watcher, error) {
+	wd, errno := unix.InotifyAddWatch(fd, dir, events)
+	if wd == -1 {
+		return nil, fmt.Errorf("adding watcher on %s: %d", dir, errno)
+	}
+	return &watcher{
+		wd:  wd,
+		dir: dir,
+	}, nil
+}
+
+func getLimit() (int, error) {
+	b, err := ioutil.ReadFile(MaximumWatchersFile)
+	if err != nil {
+		return 0, fmt.Errorf("reading from %s: %v", MaximumWatchersFile, err)
+	}
+
+	s := strings.TrimSpace(string(b))
+	m, err := strconv.Atoi(s)
+	if err != nil {
+		return 0, fmt.Errorf("converting to integer: %v", err)
+	}
+
+	return m, nil
+}