From e7f2935333d0f14433c2a3ce2c6da75b3b939ead Mon Sep 17 00:00:00 2001
From: Nick Craig-Wood <nick@craig-wood.com>
Date: Tue, 14 Nov 2017 21:00:08 +0000
Subject: [PATCH] vfs: decode flags in Open/OpenFile for debug

---
 vfs/file.go       |  1 +
 vfs/read_write.go |  3 +--
 vfs/vfs.go        | 37 +++++++++++++++++++++++++++++++++++++
 3 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/vfs/file.go b/vfs/file.go
index 11832e18f..c15992445 100644
--- a/vfs/file.go
+++ b/vfs/file.go
@@ -319,6 +319,7 @@ func (f *File) VFS() *VFS {
 //
 // We ignore O_SYNC and O_EXCL
 func (f *File) Open(flags int) (fd Handle, err error) {
+	defer fs.Trace(f, "flags=%s", decodeOpenFlags(flags))("fd=%v, err=%v", &fd, &err)
 	var (
 		write    bool // if set need write support
 		read     bool // if set need read support
diff --git a/vfs/read_write.go b/vfs/read_write.go
index 7301277ca..ed7cfea7b 100644
--- a/vfs/read_write.go
+++ b/vfs/read_write.go
@@ -95,8 +95,7 @@ func (fh *RWFileHandle) openPending(truncate bool) (err error) {
 	if rdwrMode != os.O_RDONLY {
 		fh.file.addWriters(1)
 	}
-
-	fs.Debugf(fh.remote, "Opening cached copy with flags=0x%02X", fh.flags)
+	fs.Debugf(fh.remote, "Opening cached copy with flags=%s", decodeOpenFlags(fh.flags))
 	fd, err := os.OpenFile(fh.osPath, fh.flags|os.O_CREATE, 0600)
 	if err != nil {
 		return errors.Wrap(err, "cache open file failed")
diff --git a/vfs/vfs.go b/vfs/vfs.go
index b34bcd4ee..0afa293f9 100644
--- a/vfs/vfs.go
+++ b/vfs/vfs.go
@@ -306,8 +306,45 @@ func (vfs *VFS) StatParent(name string) (dir *Dir, leaf string, err error) {
 	return dir, leaf, nil
 }
 
+// decodeOpenFlags returns a string representing the open flags
+func decodeOpenFlags(flags int) string {
+	var out []string
+	rdwrMode := flags & accessModeMask
+	switch rdwrMode {
+	case os.O_RDONLY:
+		out = append(out, "O_RDONLY")
+	case os.O_WRONLY:
+		out = append(out, "O_WRONLY")
+	case os.O_RDWR:
+		out = append(out, "O_RDWR")
+	default:
+		out = append(out, fmt.Sprintf("0x%X", rdwrMode))
+	}
+	if flags&os.O_APPEND != 0 {
+		out = append(out, "O_APPEND")
+	}
+	if flags&os.O_CREATE != 0 {
+		out = append(out, "O_CREATE")
+	}
+	if flags&os.O_EXCL != 0 {
+		out = append(out, "O_EXCL")
+	}
+	if flags&os.O_SYNC != 0 {
+		out = append(out, "O_SYNC")
+	}
+	if flags&os.O_TRUNC != 0 {
+		out = append(out, "O_TRUNC")
+	}
+	flags &^= accessModeMask | os.O_APPEND | os.O_CREATE | os.O_EXCL | os.O_SYNC | os.O_TRUNC
+	if flags != 0 {
+		out = append(out, fmt.Sprintf("0x%X", flags))
+	}
+	return strings.Join(out, "|")
+}
+
 // OpenFile a file according to the flags and perm provided
 func (vfs *VFS) OpenFile(name string, flags int, perm os.FileMode) (fd Handle, err error) {
+	defer fs.Trace(name, "flags=%s, perm=%v", decodeOpenFlags(flags), perm)("fd=%v, err=%v", &fd, &err)
 	node, err := vfs.Stat(name)
 	if err != nil {
 		if err != ENOENT || flags&os.O_CREATE == 0 {