rados: implement binding for rados_write_op_setxattr

This commit implements binding for rados_write_op_setxattr
RADOS Write operation.

Includes a unit test.

Signed-off-by: Robert Vasek <robert.vasek@cern.ch>

docs/api-status.json

@@ -970,6 +970,12 @@
         "comment": "Ensure that the object exists and that its internal version number is equal\nto \"ver\" before writing. \"ver\" should be a version number previously\nobtained with IOContext.GetLastVersion().\n PREVIEW\n\nImplements:\n void rados_read_op_assert_version(rados_read_op_t read_op,\n                                   uint64_t ver)\n",
         "added_in_version": "v0.14.0",
         "expected_stable_version": "v0.16.0"
+      },
+      {
+        "name": "WriteOp.SetXattr",
+        "comment": "Set an xattr.\n PREVIEW\n\nImplements:\n void rados_write_op_setxattr(rados_write_op_t write_op,\n                              const char * name,\n                              const char * value,\n                              size_t value_len)\n",
+        "added_in_version": "v0.14.0",
+        "expected_stable_version": "v0.16.0"
       }
     ]
   },

docs/api-status.md

@@ -24,6 +24,7 @@ ReadOp.Read | v0.14.0 | v0.16.0 |
 WriteOp.Remove | v0.14.0 | v0.16.0 | 
 ReadOp.AssertVersion | v0.14.0 | v0.16.0 | 
 WriteOp.AssertVersion | v0.14.0 | v0.16.0 | 
+WriteOp.SetXattr | v0.14.0 | v0.16.0 | 
 
 ## Package: rbd
 

rados/rados_write_op_setxattr.go

@@ -0,0 +1,34 @@
+//go:build ceph_preview
+// +build ceph_preview
+
+package rados
+
+// #cgo LDFLAGS: -lrados
+// #include <rados/librados.h>
+// #include <stdlib.h>
+//
+import "C"
+
+import (
+	"unsafe"
+)
+
+// SetXattr sets an xattr.
+//  PREVIEW
+//
+// Implements:
+//  void rados_write_op_setxattr(rados_write_op_t write_op,
+//                               const char * name,
+//                               const char * value,
+//                               size_t value_len)
+func (w *WriteOp) SetXattr(name string, value []byte) {
+	cName := C.CString(name)
+	defer C.free(unsafe.Pointer(cName))
+
+	C.rados_write_op_setxattr(
+		w.op,
+		cName,
+		(*C.char)(unsafe.Pointer(&value[0])),
+		C.size_t(len(value)),
+	)
+}

rados/rados_write_op_setxattr_test.go

@@ -0,0 +1,32 @@
+//go:build ceph_preview
+// +build ceph_preview
+
+package rados
+
+import (
+	"github.com/stretchr/testify/assert"
+)
+
+func (suite *RadosTestSuite) TestWriteOpSetXattr() {
+	suite.SetupConnection()
+	ta := assert.New(suite.T())
+
+	var (
+		oid        = "TestWriteOpSetXattr"
+		xattrName  = "attrname"
+		xattrValue = []byte("attrvalue")
+	)
+
+	// Create an object and populate it with data.
+	op1 := CreateWriteOp()
+	defer op1.Release()
+	op1.Create(CreateIdempotent)
+	op1.SetXattr(xattrName, xattrValue)
+	err := op1.Operate(suite.ioctx, oid, OperationNoFlag)
+	ta.NoError(err)
+
+	// Read object's xattrs and compare.
+	actualXattrs, err := suite.ioctx.ListXattrs(oid)
+	ta.NoError(err)
+	ta.Equal(map[string][]byte{xattrName: xattrValue}, actualXattrs)
+}