cephfs: add file method ListXattr implementing ceph_flistxattr

Add ListXattr implementing ceph_flistxattr. Add a test for the function.

Signed-off-by: John Mulligan <jmulligan@redhat.com>

cephfs/file_xattr.go

@@ -12,6 +12,7 @@ package cephfs
 import "C"
 
 import (
+	"bytes"
 	"unsafe"
 
 	"github.com/ceph/go-ceph/internal/retry"
@@ -97,3 +98,43 @@ func (f *File) GetXattr(name string) ([]byte, error) {
 	}
 	return buf[:ret], nil
 }
+
+// ListXattr returns a slice containing strings for the name of each xattr set
+// on the fie.
+//
+// Implements:
+//  int ceph_flistxattr(struct ceph_mount_info *cmount, int fd, char *list, size_t size);
+func (f *File) ListXattr() ([]string, error) {
+	if err := f.validate(); err != nil {
+		return nil, err
+	}
+
+	var (
+		ret C.int
+		err error
+		buf []byte
+	)
+	// range from 1k to 64KiB
+	retry.WithSizes(1024, 1<<16, func(size int) retry.Hint {
+		buf = make([]byte, size)
+		ret = C.ceph_flistxattr(
+			f.mount.mount,
+			f.fd,
+			(*C.char)(unsafe.Pointer(&buf[0])),
+			C.size_t(size))
+		err = getErrorIfNegative(ret)
+		return retry.DoubleSize.If(err == errRange)
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	names := make([]string, 0)
+	for _, s := range bytes.Split(buf[:ret], []byte{0}) {
+		if len(s) > 0 {
+			name := C.GoString((*C.char)(unsafe.Pointer(&s[0])))
+			names = append(names, name)
+		}
+	}
+	return names, nil
+}

cephfs/file_xattr_test.go

@@ -74,5 +74,47 @@ func TestGetSetXattr(t *testing.T) {
 		_, err = f1.GetXattr(samples[0].name)
 		assert.Error(t, err)
 	})
-
+}
+
+func TestListXattr(t *testing.T) {
+	mount := fsConnect(t)
+	defer fsDisconnect(t, mount)
+	fname := "TestListXattr.txt"
+
+	f, err := mount.Open(fname, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0666)
+	require.NoError(t, err)
+	defer func() {
+		assert.NoError(t, f.Close())
+		assert.NoError(t, mount.Unlink(fname))
+	}()
+
+	t.Run("listXattrs1", func(t *testing.T) {
+		for _, s := range samples[:1] {
+			err := f.SetXattr(s.name, s.value, XattrDefault)
+			assert.NoError(t, err)
+		}
+		xl, err := f.ListXattr()
+		assert.NoError(t, err)
+		assert.Len(t, xl, 1)
+		assert.Contains(t, xl, samples[0].name)
+	})
+
+	t.Run("listXattrs2", func(t *testing.T) {
+		for _, s := range samples[:3] {
+			err := f.SetXattr(s.name, s.value, XattrDefault)
+			assert.NoError(t, err)
+		}
+		xl, err := f.ListXattr()
+		assert.NoError(t, err)
+		assert.Len(t, xl, 3)
+		assert.Contains(t, xl, samples[0].name)
+		assert.Contains(t, xl, samples[1].name)
+		assert.Contains(t, xl, samples[2].name)
+	})
+
+	t.Run("invalidFile", func(t *testing.T) {
+		f1 := &File{}
+		_, err := f1.ListXattr()
+		assert.Error(t, err)
+	})
 }