rados/striper: add xattr support to striper package

Add support for xattr APIs to the Striper object.

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

rados/striper/xattr.go

@@ -0,0 +1,150 @@
+//go:build ceph_preview
+
+package striper
+
+// #cgo LDFLAGS: -lrados -lradosstriper
+// #include <stdlib.h>
+// #include <radosstriper/libradosstriper.h>
+import "C"
+
+import (
+	"errors"
+	"unsafe"
+)
+
+var errStopIteration = errors.New("stop iteraton")
+
+// GetXattr retrieves an extended attribute (xattr) of the given name from the
+// specified striped object.
+//
+// Implements:
+//
+//	int rados_striper_getxattr(rados_striper_t striper,
+//	                           const char *oid,
+//	                           const char *name,
+//	                           char *buf,
+//	                           size_t len);
+func (s *Striper) GetXattr(soid string, name string, data []byte) (int, error) {
+	csoid := C.CString(soid)
+	cName := C.CString(name)
+	defer C.free(unsafe.Pointer(csoid))
+	defer C.free(unsafe.Pointer(cName))
+
+	ret := C.rados_striper_getxattr(
+		s.striper,
+		csoid,
+		cName,
+		(*C.char)(unsafe.Pointer(&data[0])),
+		(C.size_t)(len(data)))
+
+	if ret >= 0 {
+		return int(ret), nil
+	}
+	return 0, getError(ret)
+}
+
+// SetXattr sets an extended attribute (xattr) of the given name on the
+// specified striped object.
+//
+// Implements:
+//
+//	int rados_striper_setxattr(rados_striper_t striper,
+//	                           const char *oid,
+//	                           const char *name,
+//	                           const char *buf,
+//	                           size_t len);
+func (s *Striper) SetXattr(soid string, name string, data []byte) error {
+	csoid := C.CString(soid)
+	cName := C.CString(name)
+	defer C.free(unsafe.Pointer(csoid))
+	defer C.free(unsafe.Pointer(cName))
+
+	ret := C.rados_striper_setxattr(
+		s.striper,
+		csoid,
+		cName,
+		(*C.char)(unsafe.Pointer(&data[0])),
+		(C.size_t)(len(data)))
+
+	return getError(ret)
+}
+
+// RmXattr removes the extended attribute (xattr) of the given name from the
+// striped object.
+//
+// Implements:
+//
+//	int rados_striper_rmxattr(rados_striper_t striper,
+//	                          const char *oid,
+//	                          const char *name);
+func (s *Striper) RmXattr(soid string, name string) error {
+	csoid := C.CString(soid)
+	cName := C.CString(name)
+	defer C.free(unsafe.Pointer(csoid))
+	defer C.free(unsafe.Pointer(cName))
+
+	ret := C.rados_striper_rmxattr(s.striper, csoid, cName)
+	return getError(ret)
+}
+
+// getXattrsNext wraps the function to fetch a xattr name/value pair
+// from the iterator. If the iterator is exhausted the error value
+// will be errStopIteration.
+//
+// Implements:
+//
+//	int rados_striper_getxattrs_next(rados_xattrs_iter_t iter,
+//	                                 const char **name,
+//	                                 const char **val,
+//	                                 size_t *len);
+func getXattrsNext(it C.rados_xattrs_iter_t) (string, []byte, error) {
+	var (
+		cName, cValue *C.char
+		cLen          C.size_t
+	)
+	defer C.free(unsafe.Pointer(cName))
+	defer C.free(unsafe.Pointer(cValue))
+
+	ret := C.rados_striper_getxattrs_next(it, &cName, &cValue, &cLen)
+	if ret < 0 {
+		return "", nil, getError(ret)
+	}
+	if cName == nil && cValue == nil {
+		return "", nil, errStopIteration
+	}
+	return C.GoString(cName), C.GoBytes(unsafe.Pointer(cValue), C.int(cLen)), nil
+}
+
+// ListXattrs returns a map containing all of the extended attributes (xattrs)
+// for a striped object. The xattr names provide the key strings and the map's
+// values are byte slices.
+//
+// Implements:
+//
+//	int rados_striper_getxattrs(rados_striper_t striper,
+//	                            const char *oid,
+//	                            rados_xattrs_iter_t *iter);
+func (s *Striper) ListXattrs(soid string) (map[string][]byte, error) {
+	csoid := C.CString(soid)
+	defer C.free(unsafe.Pointer(csoid))
+
+	var it C.rados_xattrs_iter_t
+	ret := C.rados_striper_getxattrs(s.striper, csoid, &it)
+	if ret < 0 {
+		return nil, getError(ret)
+	}
+	defer C.rados_striper_getxattrs_end(it)
+
+	m := make(map[string][]byte)
+	for {
+		xname, xvalue, err := getXattrsNext(it)
+		if err == errStopIteration {
+			break
+		}
+		if err != nil {
+			return nil, err
+		}
+		m[xname] = xvalue
+	}
+	return m, nil
+}