all: sync with master

internal/aghos/fswatcher.go

@@ -8,6 +8,8 @@ import (
 
 	"github.com/AdguardTeam/golibs/errors"
 	"github.com/AdguardTeam/golibs/log"
+	"github.com/AdguardTeam/golibs/osutil"
+	"github.com/AdguardTeam/golibs/stringutil"
 	"github.com/fsnotify/fsnotify"
 )
 
@@ -18,31 +20,38 @@ type event = struct{}
 // FSWatcher tracks all the fyle system events and notifies about those.
 //
 // TODO(e.burkov, a.garipov): Move into another package like aghfs.
+//
+// TODO(e.burkov):  Add tests.
 type FSWatcher interface {
+	// Start starts watching the added files.
+	Start() (err error)
+
+	// Close stops watching the files and closes an update channel.
 	io.Closer
 
-	// Events should return a read-only channel which notifies about events.
+	// Events returns the channel to notify about the file system events.
 	Events() (e <-chan event)
 
-	// Add should check if the file named name is accessible and starts tracking
-	// it.
+	// Add starts tracking the file.  It returns an error if the file can't be
+	// tracked.  It must not be called after Start.
 	Add(name string) (err error)
 }
 
 // osWatcher tracks the file system provided by the OS.
 type osWatcher struct {
-	// w is the actual notifier that is handled by osWatcher.
-	w *fsnotify.Watcher
+	// watcher is the actual notifier that is handled by osWatcher.
+	watcher *fsnotify.Watcher
 
 	// events is the channel to notify.
 	events chan event
+
+	// files is the set of tracked files.
+	files *stringutil.Set
 }
 
-const (
-	// osWatcherPref is a prefix for logging and wrapping errors in osWathcer's
-	// methods.
-	osWatcherPref = "os watcher"
-)
+// osWatcherPref is a prefix for logging and wrapping errors in osWathcer's
+// methods.
+const osWatcherPref = "os watcher"
 
 // NewOSWritesWatcher creates FSWatcher that tracks the real file system of the
 // OS and notifies only about writing events.
@@ -55,25 +64,27 @@ func NewOSWritesWatcher() (w FSWatcher, err error) {
 		return nil, fmt.Errorf("creating watcher: %w", err)
 	}
 
-	fsw := &osWatcher{
-		w:      watcher,
-		events: make(chan event, 1),
-	}
-
-	go fsw.handleErrors()
-	go fsw.handleEvents()
-
-	return fsw, nil
+	return &osWatcher{
+		watcher: watcher,
+		events:  make(chan event, 1),
+		files:   stringutil.NewSet(),
+	}, nil
 }
 
-// handleErrors handles accompanying errors.  It used to be called in a separate
-// goroutine.
-func (w *osWatcher) handleErrors() {
-	defer log.OnPanic(fmt.Sprintf("%s: handling errors", osWatcherPref))
+// type check
+var _ FSWatcher = (*osWatcher)(nil)
 
-	for err := range w.w.Errors {
-		log.Error("%s: %s", osWatcherPref, err)
-	}
+// Start implements the FSWatcher interface for *osWatcher.
+func (w *osWatcher) Start() (err error) {
+	go w.handleErrors()
+	go w.handleEvents()
+
+	return nil
+}
+
+// Close implements the FSWatcher interface for *osWatcher.
+func (w *osWatcher) Close() (err error) {
+	return w.watcher.Close()
 }
 
 // Events implements the FSWatcher interface for *osWatcher.
@@ -81,34 +92,42 @@ func (w *osWatcher) Events() (e <-chan event) {
 	return w.events
 }
 
-// Add implements the FSWatcher interface for *osWatcher.
+// Add implements the [FSWatcher] interface for *osWatcher.
 //
 // TODO(e.burkov):  Make it accept non-existing files to detect it's creating.
 func (w *osWatcher) Add(name string) (err error) {
 	defer func() { err = errors.Annotate(err, "%s: %w", osWatcherPref) }()
 
-	if _, err = fs.Stat(RootDirFS(), name); err != nil {
+	fi, err := fs.Stat(osutil.RootDirFS(), name)
+	if err != nil {
 		return fmt.Errorf("checking file %q: %w", name, err)
 	}
 
-	return w.w.Add(filepath.Join("/", name))
-}
+	name = filepath.Join("/", name)
+	w.files.Add(name)
 
-// Close implements the FSWatcher interface for *osWatcher.
-func (w *osWatcher) Close() (err error) {
-	return w.w.Close()
+	// Watch the directory and filter the events by the file name, since the
+	// common recomendation to the fsnotify package is to watch the directory
+	// instead of the file itself.
+	//
+	// See https://pkg.go.dev/github.com/fsnotify/fsnotify@v1.7.0#readme-watching-a-file-doesn-t-work-well.
+	if !fi.IsDir() {
+		name = filepath.Dir(name)
+	}
+
+	return w.watcher.Add(name)
 }
 
 // handleEvents notifies about the received file system's event if needed.  It
-// used to be called in a separate goroutine.
+// is intended to be used as a goroutine.
 func (w *osWatcher) handleEvents() {
 	defer log.OnPanic(fmt.Sprintf("%s: handling events", osWatcherPref))
 
 	defer close(w.events)
 
-	ch := w.w.Events
+	ch := w.watcher.Events
 	for e := range ch {
-		if e.Op&fsnotify.Write == 0 {
+		if e.Op&fsnotify.Write == 0 || !w.files.Has(e.Name) {
 			continue
 		}
 
@@ -131,3 +150,13 @@ func (w *osWatcher) handleEvents() {
 		}
 	}
 }
+
+// handleErrors handles accompanying errors.  It used to be called in a separate
+// goroutine.
+func (w *osWatcher) handleErrors() {
+	defer log.OnPanic(fmt.Sprintf("%s: handling errors", osWatcherPref))
+
+	for err := range w.watcher.Errors {
+		log.Error("%s: %s", osWatcherPref, err)
+	}
+}

internal/aghos/os.go

@@ -7,17 +7,16 @@ import (
 	"bufio"
 	"fmt"
 	"io"
-	"io/fs"
 	"os"
 	"os/exec"
 	"path"
 	"runtime"
+	"slices"
 	"strconv"
 	"strings"
 
 	"github.com/AdguardTeam/golibs/errors"
 	"github.com/AdguardTeam/golibs/log"
-	"golang.org/x/exp/slices"
 )
 
 // UnsupportedError is returned by functions and methods when a particular
@@ -155,13 +154,6 @@ func IsOpenWrt() (ok bool) {
 	return isOpenWrt()
 }
 
-// RootDirFS returns the [fs.FS] rooted at the operating system's root.  On
-// Windows it returns the fs.FS rooted at the volume of the system directory
-// (usually, C:).
-func RootDirFS() (fsys fs.FS) {
-	return rootDirFS()
-}
-
 // NotifyReconfigureSignal notifies c on receiving reconfigure signals.
 func NotifyReconfigureSignal(c chan<- os.Signal) {
 	notifyReconfigureSignal(c)

internal/aghos/os_linux.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"syscall"
 
+	"github.com/AdguardTeam/golibs/osutil"
 	"github.com/AdguardTeam/golibs/stringutil"
 )
 
@@ -40,7 +41,7 @@ func isOpenWrt() (ok bool) {
 		}
 
 		return nil, !stringutil.ContainsFold(string(data), osNameData), nil
-	}).Walk(RootDirFS(), etcReleasePattern)
+	}).Walk(osutil.RootDirFS(), etcReleasePattern)
 
 	return err == nil && ok
 }

internal/aghos/os_unix.go

@@ -3,17 +3,12 @@
 package aghos
 
 import (
-	"io/fs"
 	"os"
 	"os/signal"
 
 	"golang.org/x/sys/unix"
 )
 
-func rootDirFS() (fsys fs.FS) {
-	return os.DirFS("/")
-}
-
 func notifyReconfigureSignal(c chan<- os.Signal) {
 	signal.Notify(c, unix.SIGHUP)
 }

internal/aghos/os_windows.go

@@ -3,29 +3,13 @@
 package aghos
 
 import (
-	"io/fs"
 	"os"
 	"os/signal"
-	"path/filepath"
 	"syscall"
 
-	"github.com/AdguardTeam/golibs/log"
 	"golang.org/x/sys/windows"
 )
 
-func rootDirFS() (fsys fs.FS) {
-	// TODO(a.garipov): Use a better way if golang/go#44279 is ever resolved.
-	sysDir, err := windows.GetSystemDirectory()
-	if err != nil {
-		log.Error("aghos: getting root filesystem: %s; using C:", err)
-
-		// Assume that C: is the safe default.
-		return os.DirFS("C:")
-	}
-
-	return os.DirFS(filepath.VolumeName(sysDir))
-}
-
 func setRlimit(val uint64) (err error) {
 	return Unsupported("setrlimit")
 }