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/*
* Copyright (c) 2020-2021, Itamar S. <itamar8910@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "DIE.h"
#include "CompilationUnit.h"
#include "DwarfInfo.h"
#include <AK/ByteBuffer.h>
#include <AK/LEB128.h>
#include <AK/MemoryStream.h>
namespace Debug::Dwarf {
DIE::DIE(CompilationUnit const& unit, u32 offset, Optional<u32> parent_offset)
: m_compilation_unit(unit)
{
rehydrate_from(offset, parent_offset).release_value_but_fixme_should_propagate_errors();
}
ErrorOr<void> DIE::rehydrate_from(u32 offset, Optional<u32> parent_offset)
{
m_offset = offset;
auto stream = TRY(FixedMemoryStream::construct(m_compilation_unit.dwarf_info().debug_info_data()));
// Note: We can't just slice away from the input data here, since get_attribute_value will try to recover the original offset using seek().
TRY(stream->seek(m_offset));
m_abbreviation_code = TRY(stream->read_value<LEB128<size_t>>());
m_data_offset = TRY(stream->tell());
if (m_abbreviation_code == 0) {
// An abbreviation code of 0 ( = null DIE entry) means the end of a chain of siblings
m_tag = EntryTag::None;
} else {
auto abbreviation_info = m_compilation_unit.abbreviations_map().get(m_abbreviation_code);
VERIFY(abbreviation_info);
m_tag = abbreviation_info->tag;
m_has_children = abbreviation_info->has_children;
// We iterate the attributes data only to calculate this DIE's size
for (auto& attribute_spec : abbreviation_info->attribute_specifications) {
TRY(m_compilation_unit.dwarf_info().get_attribute_value(attribute_spec.form, attribute_spec.value, *stream, &m_compilation_unit));
}
}
m_size = TRY(stream->tell()) - m_offset;
m_parent_offset = parent_offset;
return {};
}
ErrorOr<Optional<AttributeValue>> DIE::get_attribute(Attribute const& attribute) const
{
auto stream = TRY(FixedMemoryStream::construct(m_compilation_unit.dwarf_info().debug_info_data()));
// Note: We can't just slice away from the input data here, since get_attribute_value will try to recover the original offset using seek().
TRY(stream->seek(m_data_offset));
auto abbreviation_info = m_compilation_unit.abbreviations_map().get(m_abbreviation_code);
VERIFY(abbreviation_info);
for (auto const& attribute_spec : abbreviation_info->attribute_specifications) {
auto value = TRY(m_compilation_unit.dwarf_info().get_attribute_value(attribute_spec.form, attribute_spec.value, *stream, &m_compilation_unit));
if (attribute_spec.attribute == attribute) {
return value;
}
}
return Optional<AttributeValue> {};
}
ErrorOr<void> DIE::for_each_child(Function<ErrorOr<void>(DIE const& child)> callback) const
{
if (!m_has_children)
return {};
auto current_child = DIE(m_compilation_unit, m_offset + m_size, m_offset);
while (true) {
TRY(callback(current_child));
if (current_child.is_null())
break;
if (!current_child.has_children()) {
TRY(current_child.rehydrate_from(current_child.offset() + current_child.size(), m_offset));
continue;
}
auto sibling = TRY(current_child.get_attribute(Attribute::Sibling));
u32 sibling_offset = 0;
if (sibling.has_value()) {
sibling_offset = sibling.value().as_unsigned();
} else {
// NOTE: According to the spec, the compiler doesn't have to supply the sibling information.
// When it doesn't, we have to recursively iterate the current child's children to find where they end
TRY(current_child.for_each_child([&](DIE const& sub_child) -> ErrorOr<void> {
sibling_offset = sub_child.offset() + sub_child.size();
return {};
}));
}
TRY(current_child.rehydrate_from(sibling_offset, m_offset));
}
return {};
}
}
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