From da80f91e1c1a02abce17159ed303c7666d68bf14 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@duempel.org>
Date: Tue, 7 Jan 2014 22:04:19 +0100
Subject: Directory: make some code generic, move to VarSize.hxx

---
 src/util/VarSize.hxx | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 src/util/VarSize.hxx

(limited to 'src/util')

diff --git a/src/util/VarSize.hxx b/src/util/VarSize.hxx
new file mode 100644
index 000000000..b1123b858
--- /dev/null
+++ b/src/util/VarSize.hxx
@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2008-2014 Max Kellermann <max@duempel.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef MPD_VAR_SIZE_HXX
+#define MPD_VAR_SIZE_HXX
+
+#include "Compiler.h"
+
+#include <type_traits>
+#include <utility>
+#include <new>
+
+#include <glib.h>
+
+/**
+ * Allocate and construct a variable-size object.  That is useful for
+ * example when you want to store a variable-length string as the last
+ * attribute without the overhead of a second allocation.
+ *
+ * @param T a struct/class with a variable-size last attribute
+ * @param declared_tail_size the declared size of the last element in
+ * #T
+ * @param real_tail_size the real required size of the last element in
+ * #T
+ */
+template<class T, typename... Args>
+gcc_malloc
+T *
+NewVarSize(size_t declared_tail_size, size_t real_tail_size, Args&&... args)
+{
+	static_assert(std::is_standard_layout<T>::value,
+		      "Not standard-layout");
+
+	/* determine the total size of this instance */
+	size_t size = sizeof(T) - declared_tail_size + real_tail_size;
+
+	/* allocate memory */
+	T *instance = (T *)g_malloc(size);
+
+	/* call the constructor */
+	new(instance) T(std::forward<Args>(args)...);
+
+	return instance;
+}
+
+template<typename T>
+gcc_nonnull_all
+void
+DeleteVarSize(T *instance)
+{
+	/* call the destructor */
+	instance->T::~T();
+
+	/* free memory */
+	g_free(instance);
+}
+
+#endif
-- 
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