integrate inotify syscalls

docker/Dockerfile

@@ -1,5 +1,9 @@
 FROM golang:1.9-stretch
 
+RUN useradd -ms /bin/bash myuser
+
+USER myuser
+
 WORKDIR /go/src/github.com/dominicbreuker
 
 

internal/dev/plist.go

@@ -1,12 +1,11 @@
 package dev
 
 import (
-	"fmt"
-	"io/ioutil"
 	"log"
-	"strconv"
+	"time"
 
-	"github.com/fsnotify/fsnotify"
+	"github.com/dominicbreuker/pspy/internal/inotify"
+	"github.com/dominicbreuker/pspy/internal/process"
 )
 
 type Process struct {
@@ -30,78 +29,47 @@ func Monitor() {
 }
 
 func watch() {
-	watcher, err := fsnotify.NewWatcher()
+	ping := make(chan struct{})
+	in, err := inotify.NewInotify(ping)
 	if err != nil {
-		log.Fatalf("Can't create file system watcher: %v", err)
+		log.Fatalf("Can't init inotify: %v", err)
 	}
-	defer watcher.Close()
 
-	done := make(chan bool)
+	dirs := []string{
+		"/proc",
+		"/var/log",
+		"/home",
+		"/tmp",
+	}
+
+	for _, dir := range dirs {
+		if err := in.Watch(dir); err != nil {
+			log.Fatalf("Can't create watcher: %v", err)
+		}
+	}
+
+	log.Printf("Inotify set up: %s\n", in)
+
+	procList := process.NewProcList()
+
+	ticker := time.NewTicker(50 * time.Millisecond).C
 
-	go func() {
 	for {
 		select {
-			case event := <-watcher.Events:
+		case <-ticker:
-				log.Println("event:", event)
+			refresh(in, procList)
-				if event.Op&fsnotify.Write == fsnotify.Write {
+		case <-ping:
-					log.Println("modified file:", event.Name)
+			log.Printf("PING")
-				}
+			refresh(in, procList)
-			case err := <-watcher.Errors:
-				log.Println("error:", err)
 		}
 	}
-	}()
-
-	err = watcher.Add("/tmp")
-	if err != nil {
-		log.Fatal(err)
-	}
-	<-done
 }
 
-func refresh(procList map[int]string) error {
+func refresh(in *inotify.Inotify, pl *process.ProcList) {
-	proc, err := ioutil.ReadDir("/proc")
+	in.Pause()
-	if err != nil {
+	if err := pl.Refresh(); err != nil {
-		return fmt.Errorf("opening proc dir: %v", err)
+		log.Printf("ERROR refreshing process list: %v", err)
 	}
-
+	time.Sleep(50 * time.Millisecond)
-	pids := make([]int, 0)
+	in.UnPause()
-
-	for _, f := range proc {
-		if f.IsDir() {
-			name := f.Name()
-			pid, err := strconv.Atoi(name)
-			if err != nil {
-				continue // not a pid
-			}
-			pids = append(pids, pid)
-		}
-	}
-
-	for _, pid := range pids {
-		_, ok := procList[pid]
-		if !ok {
-			cmd, err := getCmd(pid)
-			if err != nil {
-				cmd = "UNKNOWN" // process probably terminated
-			}
-			log.Printf("New process: %5d: %s\n", pid, cmd)
-			procList[pid] = cmd
-		}
-	}
-	return nil
-}
-
-func getCmd(pid int) (string, error) {
-	cmdPath := fmt.Sprintf("/proc/%d/cmdline", pid)
-	cmd, err := ioutil.ReadFile(cmdPath)
-	if err != nil {
-		return "", err
-	}
-	for i := 0; i < len(cmd); i++ {
-		if cmd[i] == 0 {
-			cmd[i] = 32
-		}
-	}
-	return string(cmd), nil
 }

internal/inotify/inotify.go

@@ -0,0 +1,65 @@
+package inotify
+
+import (
+	"fmt"
+
+	"golang.org/x/sys/unix"
+)
+
+type Inotify struct {
+	fd       int
+	watchers []*watcher
+	ping     chan struct{}
+	paused   bool
+}
+
+func NewInotify(ping chan struct{}) (*Inotify, error) {
+	fd, errno := unix.InotifyInit1(unix.IN_CLOEXEC)
+	if fd == -1 {
+		return nil, fmt.Errorf("Can't init inotify: %d", errno)
+	}
+
+	i := &Inotify{
+		fd:     fd,
+		ping:   ping,
+		paused: false,
+	}
+	go watch(i)
+
+	return i, nil
+}
+
+func (i *Inotify) Watch(dir string) error {
+	w, err := newWatcher(i.fd, dir, i.ping)
+	if err != nil {
+		return fmt.Errorf("creating watcher: %v", err)
+	}
+	i.watchers = append(i.watchers, w)
+	return nil
+}
+
+func (i *Inotify) Pause() {
+	i.paused = true
+}
+
+func (i *Inotify) UnPause() {
+	i.paused = false
+}
+
+func (i *Inotify) String() string {
+	dirs := make([]string, 0)
+	for _, w := range i.watchers {
+		dirs = append(dirs, w.dir)
+	}
+	return fmt.Sprintf("Watching: %v", dirs)
+}
+
+func watch(i *Inotify) {
+	buf := make([]byte, 1024)
+	for {
+		_, _ = unix.Read(i.fd, buf)
+		if !i.paused {
+			i.ping <- struct{}{}
+		}
+	}
+}

internal/inotify/watcher.go

@@ -0,0 +1,25 @@
+package inotify
+
+import (
+	"fmt"
+
+	"golang.org/x/sys/unix"
+)
+
+const events = unix.IN_ALL_EVENTS
+
+type watcher struct {
+	wd  int
+	dir string
+}
+
+func newWatcher(fd int, dir string, ping chan struct{}) (*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
+}

internal/process/process.go

@@ -0,0 +1,68 @@
+package process
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"strconv"
+)
+
+type ProcList map[int]string
+
+// type Proc struct {
+// 	Cmd  string
+// 	User string
+// }
+
+func NewProcList() *ProcList {
+	pl := make(ProcList)
+	return &pl
+}
+
+func (pl ProcList) Refresh() error {
+	proc, err := ioutil.ReadDir("/proc")
+	if err != nil {
+		return fmt.Errorf("opening proc dir: %v", err)
+	}
+
+	pids := make([]int, 0)
+
+	for _, f := range proc {
+		if f.IsDir() {
+			name := f.Name()
+			pid, err := strconv.Atoi(name)
+			if err != nil {
+				continue // not a pid
+			}
+			pids = append(pids, pid)
+		}
+	}
+
+	for i := len(pids) - 1; i >= 0; i-- {
+		pid := pids[i]
+		_, ok := pl[pid]
+		if !ok {
+			cmd, err := getCmd(pid)
+			if err != nil {
+				cmd = "UNKNOWN" // process probably terminated
+			}
+			log.Printf("New process: %5d: %s\n", pid, cmd)
+			pl[pid] = cmd
+		}
+	}
+	return nil
+}
+
+func getCmd(pid int) (string, error) {
+	cmdPath := fmt.Sprintf("/proc/%d/cmdline", pid)
+	cmd, err := ioutil.ReadFile(cmdPath)
+	if err != nil {
+		return "", err
+	}
+	for i := 0; i < len(cmd); i++ {
+		if cmd[i] == 0 {
+			cmd[i] = 32
+		}
+	}
+	return string(cmd), nil
+}