LibDebug: Parse DWARF information entries

We can now iterate the tree structure of the DIEs, access attribute
values and parse some very basic DWARF expressions.

Libraries/LibDebug/Dwarf/DwarfInfo.h

@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2020, Itamar S. <itamar8910@gmail.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. 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 COPYRIGHT HOLDER 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.
+ */
+
+#pragma once
+#include "CompilationUnit.h"
+#include "DwarfTypes.h"
+#include <AK/BufferStream.h>
+#include <AK/ByteBuffer.h>
+#include <AK/NonnullRefPtr.h>
+#include <AK/RefCounted.h>
+#include <AK/String.h>
+#include <Libraries/LibELF/Loader.h>
+
+namespace Dwarf {
+
+class DwarfInfo : public RefCounted<DwarfInfo> {
+public:
+    static NonnullRefPtr<DwarfInfo> create(NonnullRefPtr<const ELF::Loader> elf) { return adopt(*new DwarfInfo(elf)); }
+
+    const ByteBuffer& debug_info_data() const { return m_debug_info_data; }
+    const ByteBuffer& abbreviation_data() const { return m_abbreviation_data; }
+    const ByteBuffer& debug_strings_data() const { return m_debug_strings_data; }
+
+    template<typename Callback>
+    void for_each_compilation_unit(Callback) const;
+
+private:
+    explicit DwarfInfo(NonnullRefPtr<const ELF::Loader> elf);
+    void populate_compilation_units();
+
+    ByteBuffer section_data(const String& section_name);
+
+    NonnullRefPtr<const ELF::Loader> m_elf;
+    ByteBuffer m_debug_info_data;
+    ByteBuffer m_abbreviation_data;
+    ByteBuffer m_debug_strings_data;
+
+    Vector<Dwarf::CompilationUnit> m_compilation_units;
+};
+
+template<typename Callback>
+void DwarfInfo::for_each_compilation_unit(Callback callback) const
+{
+    for (const auto& unit : m_compilation_units) {
+        callback(unit);
+    }
+}
+
+}