From 2926a90df3ccc3ca8fca76d7ddb241fc1562f9f2 Mon Sep 17 00:00:00 2001
From: Robert Vasek <robert.vasek@cern.ch>
Date: Mon, 27 Sep 2021 14:08:50 +0200
Subject: [PATCH] rados: implement binding for rados_write_op_cmpext

This commit implements binding for rados_write_op_cmpext RADOS Write operation.
Includes a unit test.

Signed-off-by: Robert Vasek <robert.vasek@cern.ch>
---
 rados/write_op_preview.go      | 31 ++++++++++++++++++++++++++
 rados/write_op_preview_test.go | 40 ++++++++++++++++++++++++++++++++++
 2 files changed, 71 insertions(+)
 create mode 100644 rados/write_op_preview.go
 create mode 100644 rados/write_op_preview_test.go

diff --git a/rados/write_op_preview.go b/rados/write_op_preview.go
new file mode 100644
index 000000000..28e539ff8
--- /dev/null
+++ b/rados/write_op_preview.go
@@ -0,0 +1,31 @@
+// +build ceph_preview
+
+package rados
+
+// #cgo LDFLAGS: -lrados
+// #include <rados/librados.h>
+//
+import "C"
+
+import (
+	"unsafe"
+)
+
+// CmpExt ensures that given object range (extent) satisfies comparison (PREVIEW).
+//
+// Implements:
+//  void rados_write_op_cmpext(rados_write_op_t write_op,
+//                             const char * cmp_buf,
+//                             size_t cmp_len,
+//                             uint64_t off,
+//                             int * prval);
+func (w *WriteOp) CmpExt(b []byte, offset uint64, prval *int32) {
+	oe := newWriteStep(b, 0, offset)
+	w.steps = append(w.steps, oe)
+	C.rados_write_op_cmpext(
+		w.op,
+		oe.cBuffer,
+		oe.cDataLen,
+		oe.cOffset,
+		(*C.int)(unsafe.Pointer(prval)))
+}
diff --git a/rados/write_op_preview_test.go b/rados/write_op_preview_test.go
new file mode 100644
index 000000000..47738d472
--- /dev/null
+++ b/rados/write_op_preview_test.go
@@ -0,0 +1,40 @@
+// +build ceph_preview
+
+package rados
+
+import (
+	"github.com/stretchr/testify/assert"
+)
+
+func (suite *RadosTestSuite) TestWriteOpCmpExt() {
+	suite.SetupConnection()
+	ta := assert.New(suite.T())
+
+	oid := "TestWriteOpCmpExt"
+	data := []byte("compare this")
+	var prval int32
+
+	// Create an object and populate it with data.
+	op1 := CreateWriteOp()
+	defer op1.Release()
+	op1.Create(CreateIdempotent)
+	op1.WriteFull([]byte(data))
+	err := op1.Operate(suite.ioctx, oid, OperationNoFlag)
+	ta.NoError(err)
+
+	// Compare contents of the object. Should succeed.
+	op2 := CreateWriteOp()
+	defer op2.Release()
+	op2.CmpExt(data, 0, &prval)
+	err = op2.Operate(suite.ioctx, oid, OperationNoFlag)
+	ta.NoError(err)
+	ta.Equal(prval, int32(0))
+
+	// Compare contents of the object. Should fail.
+	op3 := CreateWriteOp()
+	defer op3.Release()
+	op3.CmpExt([]byte("xxx"), 0, &prval)
+	err = op3.Operate(suite.ioctx, oid, OperationNoFlag)
+	ta.Error(err)
+	ta.NotEqual(prval, int32(0))
+}