fuse: don't set flagname keyed by syscall.O_LARGEFILE

On amd64, syscall.O_LARGEFILE is 0x0, making it be ignored as a
key. However, the kernel always passes 0x8000 to the FUSE server for
the OPEN call.

The previous behavior causes crashes on 386, because the flagname is
added twice.

Change-Id: Ibabcdfef4d90e4fa4d02963d45a4d4cf2cba1ea2

fuse/print.go

@@ -54,16 +54,18 @@ var (
 		RELEASE_FLUSH: "FLUSH",
 	})
 	openFlagNames = newFlagNames(map[int64]string{
-		int64(os.O_WRONLY):         "WRONLY",
-		int64(os.O_RDWR):           "RDWR",
-		int64(os.O_APPEND):         "APPEND",
-		int64(syscall.O_ASYNC):     "ASYNC",
-		int64(os.O_CREATE):         "CREAT",
-		int64(os.O_EXCL):           "EXCL",
-		int64(syscall.O_NOCTTY):    "NOCTTY",
-		int64(syscall.O_NONBLOCK):  "NONBLOCK",
-		int64(os.O_SYNC):           "SYNC",
-		int64(os.O_TRUNC):          "TRUNC",
+		int64(os.O_WRONLY):        "WRONLY",
+		int64(os.O_RDWR):          "RDWR",
+		int64(os.O_APPEND):        "APPEND",
+		int64(syscall.O_ASYNC):    "ASYNC",
+		int64(os.O_CREATE):        "CREAT",
+		int64(os.O_EXCL):          "EXCL",
+		int64(syscall.O_NOCTTY):   "NOCTTY",
+		int64(syscall.O_NONBLOCK): "NONBLOCK",
+		int64(os.O_SYNC):          "SYNC",
+		int64(os.O_TRUNC):         "TRUNC",
+		// syscall.O_LARGEFILE is 0x0 on x86_64, but the
+		// kernel supplies 0x8000 anyway.
 		0x8000:                     "LARGEFILE",
 		int64(syscall.O_CLOEXEC):   "CLOEXEC",
 		int64(syscall.O_DIRECTORY): "DIRECTORY",

fuse/print_linux.go

@@ -11,7 +11,6 @@ import (
 
 func init() {
 	openFlagNames.set(syscall.O_DIRECT, "DIRECT")
-	openFlagNames.set(syscall.O_LARGEFILE, "LARGEFILE")
 	openFlagNames.set(syscall_O_NOATIME, "NOATIME")
 	initFlagNames.set(CAP_NO_OPENDIR_SUPPORT, "NO_OPENDIR_SUPPORT")
 	initFlagNames.set(CAP_EXPLICIT_INVAL_DATA, "EXPLICIT_INVAL_DATA")