From 8b67b395b9eb708e820bcc96c3821027f2bde360 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Thu, 13 Jun 2019 11:24:08 +0200
Subject: conf: don't crash when config directory is removed

---
 conf/storewatcher_windows.go | 25 ++++++++++++++++++++-----
 conf/zsyscall_windows.go     |  2 +-
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/conf/storewatcher_windows.go b/conf/storewatcher_windows.go
index f5cbb553..19956263 100644
--- a/conf/storewatcher_windows.go
+++ b/conf/storewatcher_windows.go
@@ -22,7 +22,7 @@ const (
 	fncSECURITY    uint32 = 0x00000100
 )
 
-//sys	findFirstChangeNotification(path *uint16, watchSubtree bool, filter uint32) (handle windows.Handle, err error) = kernel32.FindFirstChangeNotificationW
+//sys	findFirstChangeNotification(path *uint16, watchSubtree bool, filter uint32) (handle windows.Handle, err error) [failretval==windows.InvalidHandle] = kernel32.FindFirstChangeNotificationW
 //sys	findNextChangeNotification(handle windows.Handle) (err error) = kernel32.FindNextChangeNotification
 
 var haveStartedWatchingConfigDir bool
@@ -33,18 +33,30 @@ func startWatchingConfigDir() {
 	}
 	haveStartedWatchingConfigDir = true
 	go func() {
+		h := windows.InvalidHandle
+		defer func() {
+			if h != windows.InvalidHandle {
+				windows.CloseHandle(h)
+			}
+			haveStartedWatchingConfigDir = false
+		}()
+	startover:
 		configFileDir, err := tunnelConfigurationsDirectory()
 		if err != nil {
 			return
 		}
-		h, err := findFirstChangeNotification(windows.StringToUTF16Ptr(configFileDir), true, fncFILE_NAME|fncDIR_NAME|fncATTRIBUTES|fncSIZE|fncLAST_WRITE|fncLAST_ACCESS|fncCREATION|fncSECURITY)
+		h, err = findFirstChangeNotification(windows.StringToUTF16Ptr(configFileDir), true, fncFILE_NAME|fncDIR_NAME|fncATTRIBUTES|fncSIZE|fncLAST_WRITE|fncLAST_ACCESS|fncCREATION|fncSECURITY)
 		if err != nil {
-			log.Fatalf("Unable to monitor config directory: %v", err)
+			log.Printf("Unable to monitor config directory: %v", err)
+			return
 		}
 		for {
 			s, err := windows.WaitForSingleObject(h, windows.INFINITE)
 			if err != nil || s == windows.WAIT_FAILED {
-				log.Fatalf("Unable to wait on config directory watcher: %v", err)
+				log.Printf("Unable to wait on config directory watcher: %v", err)
+				windows.CloseHandle(h)
+				h = windows.InvalidHandle
+				goto startover
 			}
 
 			for cb := range storeCallbacks {
@@ -53,7 +65,10 @@ func startWatchingConfigDir() {
 
 			err = findNextChangeNotification(h)
 			if err != nil {
-				log.Fatalf("Unable to monitor config directory again: %v", err)
+				log.Printf("Unable to monitor config directory again: %v", err)
+				windows.CloseHandle(h)
+				h = windows.InvalidHandle
+				goto startover
 			}
 		}
 	}()
diff --git a/conf/zsyscall_windows.go b/conf/zsyscall_windows.go
index 7ad7bbab..4cf6d0bd 100644
--- a/conf/zsyscall_windows.go
+++ b/conf/zsyscall_windows.go
@@ -104,7 +104,7 @@ func findFirstChangeNotification(path *uint16, watchSubtree bool, filter uint32)
 	}
 	r0, _, e1 := syscall.Syscall(procFindFirstChangeNotificationW.Addr(), 3, uintptr(unsafe.Pointer(path)), uintptr(_p0), uintptr(filter))
 	handle = windows.Handle(r0)
-	if handle == 0 {
+	if handle == windows.InvalidHandle {
 		if e1 != 0 {
 			err = errnoErr(e1)
 		} else {
-- 
cgit v1.2.3-59-g8ed1b