Add recursive watcher support under Windows

This adds a new method, SetRecursive, to the Watcher structure returned
by NewWatcher. It enables the Watcher to monitor subdirectories of the
watched directories.

Currently this functionality is only supported under Windows. Calling
the SetRecursive method in all other OS-es will return an error.

fen.go

@@ -35,3 +35,9 @@ func (w *Watcher) Add(name string) error {
 func (w *Watcher) Remove(name string) error {
 	return nil
 }
+
+// SetRecursive enables watches to also monitor subdirectories. Currently
+// only supported under Windows.
+func (w *Watcher) SetRecursive() error {
+	return nil
+}

inotify.go

@@ -162,6 +162,12 @@ func (w *Watcher) Remove(name string) error {
 	return nil
 }
 
+// SetRecursive enables watches to also monitor subdirectories. Currently
+// only supported under Windows.
+func (w *Watcher) SetRecursive() error {
+	return errors.New("recursion not supported")
+}
+
 type watch struct {
 	wd    uint32 // Watch descriptor (as returned by the inotify_add_watch() syscall)
 	flags uint32 // inotify flags of this watch (see inotify(7) for the list of valid flags)

kqueue.go

@@ -147,6 +147,12 @@ func (w *Watcher) Remove(name string) error {
 	return nil
 }
 
+// SetRecursive enables watches to also monitor subdirectories. Currently
+// only supported under Windows.
+func (w *Watcher) SetRecursive() error {
+	return errors.New("recursion not supported")
+}
+
 // Watch all events (except NOTE_EXTEND, NOTE_LINK, NOTE_REVOKE)
 const noteAllEvents = unix.NOTE_DELETE | unix.NOTE_WRITE | unix.NOTE_ATTRIB | unix.NOTE_RENAME
 

windows.go

@@ -13,20 +13,22 @@ import (
 	"path/filepath"
 	"runtime"
 	"sync"
+	"sync/atomic"
 	"syscall"
 	"unsafe"
 )
 
 // Watcher watches a set of files, delivering events to a channel.
 type Watcher struct {
-	Events   chan Event
-	Errors   chan error
-	isClosed bool           // Set to true when Close() is first called
-	mu       sync.Mutex     // Map access
-	port     syscall.Handle // Handle to completion port
-	watches  watchMap       // Map of watches (key: i-number)
-	input    chan *input    // Inputs to the reader are sent on this channel
-	quit     chan chan<- error
+	Events       chan Event
+	Errors       chan error
+	isClosed     bool           // Set to true when Close() is first called
+	mu           sync.Mutex     // Map access
+	port         syscall.Handle // Handle to completion port
+	watches      watchMap       // Map of watches (key: i-number)
+	input        chan *input    // Inputs to the reader are sent on this channel
+	quit         chan chan<- error
+	watchSubTree uint32
 }
 
 // NewWatcher establishes a new watcher with the underlying OS and begins waiting for events.
@@ -95,6 +97,13 @@ func (w *Watcher) Remove(name string) error {
 	return <-in.reply
 }
 
+// SetRecursive enables watches to also monitor subdirectories. Currently
+// only supported under Windows.
+func (w *Watcher) SetRecursive() error {
+	atomic.StoreUint32(&w.watchSubTree, 1)
+	return nil
+}
+
 const (
 	// Options for AddWatch
 	sysFSONESHOT = 0x80000000
@@ -348,7 +357,8 @@ func (w *Watcher) startRead(watch *watch) error {
 		return nil
 	}
 	e := syscall.ReadDirectoryChanges(watch.ino.handle, &watch.buf[0],
-		uint32(unsafe.Sizeof(watch.buf)), false, mask, nil, &watch.ov, 0)
+		uint32(unsafe.Sizeof(watch.buf)), atomic.LoadUint32(&w.watchSubTree) != 0,
+		mask, nil, &watch.ov, 0)
 	if e != nil {
 		err := os.NewSyscallError("ReadDirectoryChanges", e)
 		if e == syscall.ERROR_ACCESS_DENIED && watch.mask&provisional == 0 {