+// Discover adds a UnixVolume for every directory named "keep" that is
+// located at the top level of a device- or tmpfs-backed mount point
+// other than "/". It returns the number of volumes added.
+func (vs *unixVolumeAdder) Discover() int {
+ added := 0
+ f, err := os.Open(ProcMounts)
+ if err != nil {
+ log.Fatalf("opening %s: %s", ProcMounts, err)
+ }
+ scanner := bufio.NewScanner(f)
+ for scanner.Scan() {
+ args := strings.Fields(scanner.Text())
+ if err := scanner.Err(); err != nil {
+ log.Fatalf("reading %s: %s", ProcMounts, err)
+ }
+ dev, mount := args[0], args[1]
+ if mount == "/" {
+ continue
+ }
+ if dev != "tmpfs" && !strings.HasPrefix(dev, "/dev/") {
+ continue
+ }
+ keepdir := mount + "/keep"
+ if st, err := os.Stat(keepdir); err != nil || !st.IsDir() {
+ continue
+ }
+ // Set the -readonly flag (but only for this volume)
+ // if the filesystem is mounted readonly.
+ flagReadonlyWas := flagReadonly
+ for _, fsopt := range strings.Split(args[3], ",") {
+ if fsopt == "ro" {
+ flagReadonly = true
+ break
+ }
+ if fsopt == "rw" {
+ break
+ }
+ }
+ if err := vs.Set(keepdir); err != nil {
+ log.Printf("adding %q: %s", keepdir, err)
+ } else {
+ added++
+ }
+ flagReadonly = flagReadonlyWas