Fix FIFO handling on Solaris

xattr_solaris.go

@@ -24,7 +24,7 @@ const (
 )
 
 func getxattr(path string, name string, data []byte) (int, error) {
-	f, err := os.OpenFile(path, os.O_RDONLY, 0)
+	f, err := openNonblock(path)
 	if err != nil {
 		return 0, err
 	}
@@ -50,7 +50,7 @@ func fgetxattr(f *os.File, name string, data []byte) (int, error) {
 }
 
 func setxattr(path string, name string, data []byte, flags int) error {
-	f, err := os.OpenFile(path, os.O_RDONLY, 0)
+	f, err := openNonblock(path)
 	if err != nil {
 		return err
 	}
@@ -87,7 +87,8 @@ func fsetxattr(f *os.File, name string, data []byte, flags int) error {
 }
 
 func removexattr(path string, name string) error {
-	fd, err := unix.Open(path, unix.O_RDONLY|unix.O_XATTR, 0)
+	mode := unix.O_RDONLY | unix.O_XATTR | unix.O_NONBLOCK | unix.O_CLOEXEC
+	fd, err := unix.Open(path, mode, 0)
 	if err != nil {
 		return err
 	}
@@ -114,7 +115,7 @@ func fremovexattr(f *os.File, name string) error {
 }
 
 func listxattr(path string, data []byte) (int, error) {
-	f, err := os.OpenFile(path, os.O_RDONLY, 0)
+	f, err := openNonblock(path)
 	if err != nil {
 		return 0, err
 	}
@@ -151,8 +152,17 @@ func flistxattr(f *os.File, data []byte) (int, error) {
 	return copy(data, buf), nil
 }
 
+// Like os.Open, but passes O_NONBLOCK to the open(2) syscall.
+func openNonblock(path string) (*os.File, error) {
+	fd, err := unix.Open(path, unix.O_RDONLY|unix.O_CLOEXEC|unix.O_NONBLOCK, 0)
+	if err != nil {
+		return nil, err
+	}
+	return os.NewFile(uintptr(fd), path), err
+}
+
 // stringsFromByteSlice converts a sequence of attributes to a []string.
-// On Darwin and Linux, each entry is a NULL-terminated string.
+// We simulate Linux/Darwin, where each entry is a NULL-terminated string.
 func stringsFromByteSlice(buf []byte) (result []string) {
 	offset := 0
 	for index, b := range buf {

xattr_test.go

@@ -8,9 +8,12 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
+	"path/filepath"
 	"runtime"
 	"syscall"
 	"testing"
+
+	"golang.org/x/sys/unix"
 )
 
 const UserPrefix = "user."
@@ -260,6 +263,30 @@ func TestLargeVal(t *testing.T) {
 	}
 }
 
+// Get should work on a FIFO that is not opened by any other process.
+// This is mainly relevant on Solaris, where getting the attributes
+// requires opening the file and doing that the wrong way blocks the caller.
+func TestFIFO(t *testing.T) {
+	d, err := ioutil.TempDir("", "pkg-xattr-testfifo-*")
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Log("tempdir:", d)
+	defer os.RemoveAll(d)
+
+	fifo := filepath.Join(d, "fifo")
+	err = unix.Mkfifo(fifo, 0777)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// We only care about this not blocking.
+	_ = Set(fifo, "foo", []byte("bar"))
+	_, _ = Get(fifo, "foo")
+	_, _ = List(fifo)
+	_ = Remove(fifo, "foo")
+}
+
 // checkIfError calls t.Skip() if the underlying syscall.Errno is
 // ENOTSUP or EOPNOTSUPP. It calls t.Fatal() on any other non-zero error.
 func checkIfError(t *testing.T, err error) {