bytecode_ptr: new smart pointer type

bytecode_ptr<T> is an aligned_unique_ptr<T> that can be queried for its
size and alignment.

src/util/bytecode_ptr.h

@@ -0,0 +1,126 @@
+/*
+ * Copyright (c) 2017, Intel Corporation
+ *
+ * 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.
+ *  * Neither the name of Intel Corporation nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * 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 COPYRIGHT OWNER 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.
+ */
+
+/**
+ * \file
+ * \brief bytecode_ptr: Smart pointer that knows its length and alignment.
+ */
+
+#ifndef UTIL_BYTECODE_PTR_H
+#define UTIL_BYTECODE_PTR_H
+
+#include "util/alloc.h"
+
+#include <cstring>
+#include <memory>
+
+namespace ue2 {
+
+/**
+ * \brief Smart pointer that knows its length and alignment.
+ *
+ * This is intended to be used for flat aligned memory regions that will
+ * eventually end up copied into the Hyperscan bytecode.
+ */
+template<typename T> class bytecode_ptr {
+public:
+    bytecode_ptr() = default;
+    explicit bytecode_ptr(size_t size, size_t align = alignof(T))
+        : bytes(size), alignment(align) {
+        // posix_memalign doesn't like us asking for smaller alignment.
+        size_t mem_align = std::max(align, sizeof(void *));
+        ptr.reset(static_cast<T *>(aligned_malloc_internal(size, mem_align)));
+        if (!ptr) {
+            throw std::bad_alloc();
+        }
+        std::memset(ptr.get(), 0, bytes);
+    }
+
+    bytecode_ptr(std::nullptr_t) {}
+
+    T *get() { return ptr.get(); };
+    const T *get() const { return ptr.get(); };
+
+    T &operator*() { return *ptr; }
+    const T &operator*() const { return *ptr; }
+
+    T *operator->() { return ptr.get(); }
+    const T *operator->() const { return ptr.get(); }
+
+    explicit operator bool() const { return ptr != nullptr; }
+
+    /** \brief Move converter for shared_ptr. */
+    template <typename ST, class = typename std::enable_if<
+                               std::is_convertible<T *, ST *>::value>::type>
+    operator std::shared_ptr<ST>() && {
+        auto d = ptr.get_deleter();
+        return std::shared_ptr<ST>(ptr.release(), d);
+    }
+
+    void reset(T* p = nullptr) { ptr.reset(p); }
+
+    void swap(bytecode_ptr &other) {
+        using std::swap;
+        swap(ptr, other.ptr);
+        swap(bytes, other.bytes);
+        swap(alignment, other.alignment);
+    }
+
+    /** \brief Returns size of the memory region in bytes. */
+    size_t size() const { return bytes; }
+
+    /** \brief Returns alignment of the memory region in bytes. */
+    size_t align() const { return alignment; }
+
+    bool operator==(const bytecode_ptr &a) const { return ptr == a.ptr; }
+    bool operator!=(const bytecode_ptr &a) const { return ptr != a.ptr; }
+    bool operator<(const bytecode_ptr &a) const { return ptr < a.ptr; }
+    bool operator<=(const bytecode_ptr &a) const { return ptr <= a.ptr; }
+    bool operator>(const bytecode_ptr &a) const { return ptr > a.ptr; }
+    bool operator>=(const bytecode_ptr &a) const { return ptr >= a.ptr; }
+
+private:
+    /** \brief Deleter function for std::unique_ptr. */
+    template <typename DT> struct deleter {
+        void operator()(DT *p) const { aligned_free_internal(p); }
+    };
+
+    std::unique_ptr<T, deleter<T>> ptr = nullptr; //!< Underlying pointer.
+    size_t bytes = 0; //!< Size of memory region in bytes.
+    size_t alignment = 0; //!< Alignment of memory region in bytes.
+};
+
+template<typename T>
+inline bytecode_ptr<T> make_bytecode_ptr(size_t size,
+                                         size_t align = alignof(T)) {
+    return bytecode_ptr<T>(size, align);
+}
+
+} // namespace ue2
+
+#endif // UTIL_BYTECODE_PTR_H