[#27] util/signature: Fix staticcheck warning

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

util/signature/buffer.go

@@ -4,26 +4,30 @@ import "sync"
 
 const poolSliceMaxSize = 64 * 1024
 
+type buffer struct {
+	data []byte
+}
+
 var buffersPool = sync.Pool{
 	New: func() any {
-		return make([]byte, 0)
+		return new(buffer)
 	},
 }
 
-func newBufferFromPool(size int) []byte {
-	result := buffersPool.Get().([]byte)
-	if cap(result) < size {
-		result = make([]byte, size)
+func newBufferFromPool(size int) *buffer {
+	result := buffersPool.Get().(*buffer)
+	if cap(result.data) < size {
+		result.data = make([]byte, size)
 	} else {
-		result = result[:size]
+		result.data = result.data[:size]
 	}
 	return result
 }
 
-func returnBufferToPool(buf []byte) {
-	if cap(buf) > poolSliceMaxSize {
+func returnBufferToPool(buf *buffer) {
+	if cap(buf.data) > poolSliceMaxSize {
 		return
 	}
-	buf = buf[:0]
+	buf.data = buf.data[:0]
 	buffersPool.Put(buf)
 }