YT-19210: expose YQL shared library for YT.

After this, a new target libyqlplugin.so appears. in open-source cmake build.
Diff in open-source YDB repo looks like the following: https://paste.yandex-team.ru/f302bdb4-7ef2-4362-91c7-6ca45f329264

1 files changed, 38 insertions, 0 deletions

diff --git a/library/cpp/skiff/zerocopy_output_writer.cpp b/library/cpp/skiff/zerocopy_output_writer.cpp
new file mode 100644
index 0000000000..49492b55a4
--- /dev/null
+++ b/library/cpp/skiff/zerocopy_output_writer.cpp
@@ -0,0 +1,38 @@
+#include "zerocopy_output_writer.h"
+
+namespace NSkiff {
+
+////////////////////////////////////////////////////////////////////////////////
+
+TZeroCopyOutputStreamWriter::TZeroCopyOutputStreamWriter(IZeroCopyOutput* output)
+    : Output_(output)
+{
+    ObtainNextBlock();
+}
+
+TZeroCopyOutputStreamWriter::~TZeroCopyOutputStreamWriter()
+{
+    if (RemainingBytes_ > 0) {
+        UndoRemaining();
+    }
+}
+
+void TZeroCopyOutputStreamWriter::ObtainNextBlock()
+{
+    if (RemainingBytes_ > 0) {
+        UndoRemaining();
+    }
+    RemainingBytes_ = Output_->Next(&Current_);
+    TotalWrittenBlockSize_ += RemainingBytes_;
+}
+
+void TZeroCopyOutputStreamWriter::UndoRemaining()
+{
+    Output_->Undo(RemainingBytes_);
+    TotalWrittenBlockSize_ -= RemainingBytes_;
+    RemainingBytes_ = 0;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+} // namespace NSkiff