Add an inotify watcher utility using channels; use it.

The interface of inotify/inutil.Watcher more resembles
golang.org/x/exp/inotify; with it using channels instead of repeated calls
to Read().

In my use-case, this is useful because it allows implementing a "read"
(select, really) that doesn't block Close(); which is required to handle
the TERM signal correctly.

1 files changed, 65 insertions, 45 deletions

diff --git a/src/nshd/hackers_git/hackers_watch.go b/src/nshd/hackers_git/hackers_watch.go
index c10ec78..666237b 100644
--- a/src/nshd/hackers_git/hackers_watch.go
+++ b/src/nshd/hackers_git/hackers_watch.go
@@ -2,6 +2,7 @@ package hackers_git
 
 import (
 	"inotify"
+	"inotify/inutil"
 	"os"
 	"path/filepath"
 	"sd_daemon/logger"
@@ -49,6 +50,7 @@ func (o *Hackers) unwatchHomedir(wd inotify.Wd) {
 func (o *Hackers) close() {
 	if o.in_fd != nil {
 		o.in_fd.Close()
+		defer o.workers.Wait()
 	}
 	o.in_wd_home = -1
 	o.in_wd_yaml = -1
@@ -60,7 +62,7 @@ func (o *Hackers) close() {
 
 func (o *Hackers) reload() (err error) {
 	o.close()
-	o.in_fd, err = inotify.InotifyInit()                                    ; if err != nil { return }
+	o.in_fd, err = inutil.WatcherInit()                                     ; if err != nil { return }
 	o.in_wd_home, err = o.in_fd.AddWatch("/home"      , in_DIR|in_CHILD_ADD); if err != nil { return }
 	o.in_wd_yaml, err = o.in_fd.AddWatch(o.Cfg.Yamldir, in_DIR|in_CHILD_ANY); if err != nil { return }
 
@@ -73,6 +75,12 @@ func (o *Hackers) reload() (err error) {
 		o.load_yaml_file(filename, false)
 	}
 
+	go func() {
+		defer lsb.Recover()
+		defer o.workers.Done()
+		o.worker()
+	}()
+
 	err = nil
 	return
 }
@@ -160,55 +168,67 @@ func (o *Hackers) worker() {
 	if err != nil {
 		worker_error("failed to load %q: %v", o.Cfg.Yamldir, err)
 	}
-	for event, err := o.in_fd.Read(); err == nil; event, err = o.in_fd.Read() {
-		switch event.Wd {
-		case o.in_wd_yaml:
-			// handle updates to yaml files
-			if event.Mask&in_DIR_INVALID != 0 {
-				err := o.Reload()
-				if err != nil {
-					worker_error("failed to reload hackers.git yaml directory: %v", err)
-
-				}
-				err = os.Chdir(o.Cfg.Yamldir)
-				if err != nil {
-					worker_error("failed to load %q: %v", o.Cfg.Yamldir, err)
+Loop:
+	for {
+		select {
+		case event, ok := <-o.in_fd.Events:
+			if !ok {
+				break Loop
+			}
+			switch event.Wd {
+			case o.in_wd_yaml:
+				// handle updates to yaml files
+				if event.Mask&in_DIR_INVALID != 0 {
+					err := o.Reload()
+					if err != nil {
+						worker_error("failed to reload hackers.git yaml directory: %v", err)
+
+					}
+					err = os.Chdir(o.Cfg.Yamldir)
+					if err != nil {
+						worker_error("failed to load %q: %v", o.Cfg.Yamldir, err)
+					}
+				} else if event.Mask&in_CHILD_ANY != 0 {
+					if event.Name == nil {
+						panic("recieved child event from inotify, but no child name")
+					}
+					o.load_yaml_file(o.Cfg.Yamldir + "/" + *event.Name, true)
+				} else {
+					panic("recieved non-subscribed inotify event from kernel")
 				}
-			} else if event.Mask&in_CHILD_ANY != 0 {
-				if event.Name == nil {
-					panic("recieved child event from inotify, but no child name")
+			case o.in_wd_home:
+				if event.Mask&in_DIR_INVALID != 0 {
+					err := o.Reload()
+					if err != nil {
+						panic(err)
+					}
+				} else if event.Mask&inotify.IN_ISDIR != 0 {
+					// handle added home directory
+					o.worker_watch_homedirs()
 				}
-				o.load_yaml_file(o.Cfg.Yamldir + "/" + *event.Name, true)
-			} else {
-				panic("recieved non-subscribed inotify event from kernel")
-			}
-		case o.in_wd_home:
-			if event.Mask&in_DIR_INVALID != 0 {
-				err := o.Reload()
-				if err != nil {
-					panic(err)
+			default:
+				// handle a change to someone's password
+				if event.Mask&in_DIR_INVALID != 0 {
+					o.unwatchHomedir(event.Wd)
+					o.worker_watch_homedirs()
+				} else if event.Name != nil {
+					if *event.Name == ".password" {
+						func() {
+							o.lock.Lock()
+							defer o.lock.Unlock()
+							o.load_user_password(o.in_wd2uid[event.Wd])
+						}()
+					}
+				} else {
+					logger.Debug("hackers.git: event didn't match: %#v", event)
 				}
-			} else if event.Mask&inotify.IN_ISDIR != 0 {
-				// handle added home directory
-				o.worker_watch_homedirs()
 			}
-		default:
-			// handle a change to someone's password
-			if event.Mask&in_DIR_INVALID != 0 {
-				o.unwatchHomedir(event.Wd)
-				o.worker_watch_homedirs()
-			} else if event.Name != nil {
-				if *event.Name == ".password" {
-					func() {
-						o.lock.Lock()
-						defer o.lock.Unlock()
-						o.load_user_password(o.in_wd2uid[event.Wd])
-					}()
-				}
-			} else {
-				logger.Debug("hackers.git: event didn't match: %#v", event)
+		case err, ok := <-o.in_fd.Errors:
+			if !ok {
+				break Loop
 			}
+			logger.Warning("hackers.git: inotify error: %v", err)
 		}
 	}
-	logger.Info("Stopped hackers.git inotify watcher")
+	logger.Info("hackers.git: Stopped inotify watcher")
 }