[Mammoth] Move request/response context to ipc/ folder.

lib/mammoth/ipc/response_context.h

@@ -0,0 +1,41 @@
+#pragma once
+
+#include <glacier/status/error.h>
+#include <zcall.h>
+#include <ztypes.h>
+
+class ResponseContext {
+ public:
+  ResponseContext(z_cap_t reply_port) : reply_port_(reply_port) {}
+
+  ResponseContext(ResponseContext&) = delete;
+
+  template <typename T>
+  glcr::ErrorCode WriteStruct(const T& response) {
+    // FIXME: Here and below probably don't count as written on error.
+    written_ = true;
+    return ZReplyPortSend(reply_port_, sizeof(T), &response, 0, nullptr);
+  }
+
+  template <typename T>
+  glcr::ErrorCode WriteStructWithCap(const T& response, z_cap_t capability) {
+    written_ = true;
+    return ZReplyPortSend(reply_port_, sizeof(T), &response, 1, &capability);
+  }
+
+  glcr::ErrorCode WriteError(glcr::ErrorCode code) {
+    uint64_t response[2]{
+        static_cast<uint64_t>(-1),
+        code,
+    };
+    written_ = true;
+    return static_cast<glcr::ErrorCode>(
+        ZReplyPortSend(reply_port_, sizeof(response), &response, 0, nullptr));
+  }
+
+  bool HasWritten() { return written_; }
+
+ private:
+  z_cap_t reply_port_;
+  bool written_ = false;
+};