syscall: add O_DIRECTORY for js

Change-Id: I2022fa27b072f9b34413a04a794aeb6d3c02166c
Reviewed-on: https://go-review.googlesource.com/c/go/+/606658


Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>

src/syscall/fs_js.go

@@ -23,12 +23,13 @@ var constants = jsFS.Get("constants")
 var uint8Array = js.Global().Get("Uint8Array")
 
 var (
-	nodeWRONLY = constants.Get("O_WRONLY").Int()
-	nodeRDWR   = constants.Get("O_RDWR").Int()
-	nodeCREATE = constants.Get("O_CREAT").Int()
-	nodeTRUNC  = constants.Get("O_TRUNC").Int()
-	nodeAPPEND = constants.Get("O_APPEND").Int()
-	nodeEXCL   = constants.Get("O_EXCL").Int()
+	nodeWRONLY    = constants.Get("O_WRONLY").Int()
+	nodeRDWR      = constants.Get("O_RDWR").Int()
+	nodeCREATE    = constants.Get("O_CREAT").Int()
+	nodeTRUNC     = constants.Get("O_TRUNC").Int()
+	nodeAPPEND    = constants.Get("O_APPEND").Int()
+	nodeEXCL      = constants.Get("O_EXCL").Int()
+	nodeDIRECTORY = constants.Get("O_DIRECTORY").Int()
 )
 
 type jsFile struct {
@@ -83,6 +84,9 @@ func Open(path string, openmode int, perm uint32) (int, error) {
 	if openmode&O_SYNC != 0 {
 		return 0, errors.New("syscall.Open: O_SYNC is not supported by js/wasm")
 	}
+	if openmode&O_DIRECTORY != 0 {
+		flags |= nodeDIRECTORY
+	}
 
 	jsFD, err := fsCall("open", path, flags, perm)
 	if err != nil {

src/syscall/syscall_js.go

@@ -128,12 +128,13 @@ const (
 	O_WRONLY = 1
 	O_RDWR   = 2
 
-	O_CREAT  = 0100
-	O_CREATE = O_CREAT
-	O_TRUNC  = 01000
-	O_APPEND = 02000
-	O_EXCL   = 0200
-	O_SYNC   = 010000
+	O_CREAT     = 0100
+	O_CREATE    = O_CREAT
+	O_TRUNC     = 01000
+	O_APPEND    = 02000
+	O_EXCL      = 0200
+	O_SYNC      = 010000
+	O_DIRECTORY = 020000
 
 	O_CLOEXEC = 0
 )