rbd: add feature check to see if GroupSnapGetInfo is available

internal/rbd/features/dlsym.go

@@ -0,0 +1,48 @@
+/*
+Copyright 2024 The Ceph-CSI Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package features
+
+/*
+#cgo LDFLAGS: -ldl
+#include <stdlib.h>
+#include <dlfcn.h>
+*/
+import "C"
+
+import (
+	"fmt"
+	"unsafe"
+)
+
+// dlsym checks if the given symbol is provided by the currently loaded
+// libraries. If the symbol is available, no error is returned.
+func dlsym(symbol string) error {
+	c_symbol := C.CString(symbol)
+	//nolint:nlreturn // linter complains about missing empty line!?
+	defer C.free(unsafe.Pointer(c_symbol))
+
+	// clear dlerror before looking up the symbol
+	C.dlerror()
+	_ = C.dlsym(nil, c_symbol)
+	e := C.dlerror()
+	err := C.GoString(e)
+	if err != "" {
+		return fmt.Errorf("dlsym: %s", err)
+	}
+
+	return nil
+}

internal/rbd/features/features.go

@@ -0,0 +1,58 @@
+/*
+Copyright 2024 The Ceph-CSI Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package features
+
+/*
+#cgo LDFLAGS: -lrbd
+#include <rbd/librbd.h>
+*/
+import "C"
+
+import (
+	"strings"
+	"sync"
+)
+
+var (
+	groupGetSnapInfoOnce      sync.Once
+	errGroupGetSnapInfo       error
+	groupGetSnapInfoSupported = false
+)
+
+// SupportsGroupSnapGetInfo detects if librbd has the rbd_group_snap_get_info
+// function.
+func SupportsGroupSnapGetInfo() (bool, error) {
+	groupGetSnapInfoOnce.Do(func() {
+		// make sure librbd.so.x is loaded, might not (yet) be the case
+		// if no rbd functions are called
+		var opts C.rbd_image_options_t
+		//nolint:gocritic // ignore result of rbd_image_options functions
+		C.rbd_image_options_create(&opts)
+		C.rbd_image_options_destroy(opts)
+
+		// check for rbd_group_snap_get_info() in loaded libs/symbols
+		errGroupGetSnapInfo = dlsym("rbd_group_snap_get_info")
+
+		if errGroupGetSnapInfo == nil {
+			groupGetSnapInfoSupported = true
+		} else if strings.Contains(errGroupGetSnapInfo.Error(), "undefined symbol") {
+			errGroupGetSnapInfo = nil
+		}
+	})
+
+	return groupGetSnapInfoSupported, errGroupGetSnapInfo
+}

internal/rbd/features/features_test.go

@@ -0,0 +1,32 @@
+/*
+Copyright 2024 ceph-csi authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package features
+
+import (
+	"testing"
+)
+
+func TestSupportsGroupSnapGetInfo(t *testing.T) {
+	t.Parallel()
+
+	supported, err := SupportsGroupSnapGetInfo()
+	if err != nil {
+		t.Errorf("failed to check support for GroupSnapGetInfo: %v", err)
+	}
+
+	t.Logf("GroupSnapGetInfo supported: %t", supported)
+}