gofer: ignore unsupported files

'ls' will hang if there is any FIFO in this path. So
return EPERM if unsupported file occurs and add NONBLOCK flag
when opening file to avoid blocking on FIFO read.

Signed-off-by: Liu Hua <sdu.liu@huawei.com>
Change-Id: I8b9a2a48322118d8ad531dd226395438123eb047
PiperOrigin-RevId: 241406726

1 files changed, 18 insertions, 4 deletions

diff --git a/runsc/fsgofer/fsgofer.go b/runsc/fsgofer/fsgofer.go
index 9955d0750..1d64458e5 100644
--- a/runsc/fsgofer/fsgofer.go
+++ b/runsc/fsgofer/fsgofer.go
@@ -52,6 +52,7 @@ const (
 	regular fileType = iota
 	directory
 	symlink
+	unknown
 )
 
 // String implements fmt.Stringer.
@@ -221,9 +222,11 @@ type localFile struct {
 
 func openAnyFile(parent *localFile, name string) (*os.File, string, error) {
 	// Attempt to open file in the following mode in order:
-	//   1. RDONLY: for all files, works for directories and ro mounts too
+	//   1. RDONLY | NONBLOCK: for all files, works for directories and ro mounts too.
+	//      Use non-blocking to prevent getting stuck inside open(2) for FIFOs. This option
+	//      has no effect on regular files.
 	//   2. PATH: for symlinks
-	modes := []int{syscall.O_RDONLY, unix.O_PATH}
+	modes := []int{syscall.O_RDONLY | syscall.O_NONBLOCK, unix.O_PATH}
 
 	var err error
 	var fd int
@@ -252,7 +255,7 @@ func openAnyFile(parent *localFile, name string) (*os.File, string, error) {
 	return os.NewFile(uintptr(fd), newPath), newPath, nil
 }
 
-func newLocalFile(a *attachPoint, file *os.File, path string, stat syscall.Stat_t) (*localFile, error) {
+func getSupportedFileType(stat syscall.Stat_t) (fileType, error) {
 	var ft fileType
 	switch stat.Mode & syscall.S_IFMT {
 	case syscall.S_IFREG:
@@ -262,8 +265,17 @@ func newLocalFile(a *attachPoint, file *os.File, path string, stat syscall.Stat_
 	case syscall.S_IFLNK:
 		ft = symlink
 	default:
-		return nil, syscall.EINVAL
+		return unknown, syscall.EPERM
 	}
+	return ft, nil
+}
+
+func newLocalFile(a *attachPoint, file *os.File, path string, stat syscall.Stat_t) (*localFile, error) {
+	ft, err := getSupportedFileType(stat)
+	if err != nil {
+		return nil, err
+	}
+
 	return &localFile{
 		attachPoint: a,
 		hostPath:    path,
@@ -484,10 +496,12 @@ func (l *localFile) Walk(names []string) ([]p9.QID, p9.File, error) {
 		}
 		stat, err := stat(int(f.Fd()))
 		if err != nil {
+			f.Close()
 			return nil, nil, extractErrno(err)
 		}
 		c, err := newLocalFile(last.attachPoint, f, path, stat)
 		if err != nil {
+			f.Close()
 			return nil, nil, extractErrno(err)
 		}