Android Dynamic Partitions metadata: GraphViz block diagram (.dot) source

The metadata stored by Android at the beginning of a "super" partition, which is what it calls a disk partition that holds one or more Dynamic Partitions. Dynamic Partitions do more or less the same thing that LVM does on Linux, allowing Android to map ranges of non-contiguous extents to a single logical device. This metadata holds that mapping.

Application

Android

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KS implementation details

License: CC0-1.0
Minimal Kaitai Struct required: 0.9

This page hosts a formal specification of Android Dynamic Partitions metadata using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

GraphViz block diagram source

android_super.dot

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digraph {
	rankdir=LR;
	node [shape=plaintext];
	subgraph cluster__android_super {
		label="AndroidSuper";
		graph[style=dotted];

		android_super__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
			<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
		</TABLE>>];
		android_super__inst__root [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
			<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
			<TR><TD PORT="root_pos">4096</TD><TD PORT="root_size">...</TD><TD>Root</TD><TD PORT="root_type">root</TD></TR>
		</TABLE>>];
		subgraph cluster__root {
			label="AndroidSuper::Root";
			graph[style=dotted];

			root__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
				<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
				<TR><TD PORT="primary_geometry_pos">0</TD><TD PORT="primary_geometry_size">4096</TD><TD>Geometry</TD><TD PORT="primary_geometry_type">primary_geometry</TD></TR>
				<TR><TD PORT="backup_geometry_pos">4096</TD><TD PORT="backup_geometry_size">4096</TD><TD>Geometry</TD><TD PORT="backup_geometry_type">backup_geometry</TD></TR>
				<TR><TD PORT="primary_metadata_pos">8192</TD><TD PORT="primary_metadata_size">primary_geometry.metadata_max_size</TD><TD>Metadata</TD><TD PORT="primary_metadata_type">primary_metadata</TD></TR>
				<TR><TD COLSPAN="4" PORT="primary_metadata__repeat">repeat primary_geometry.metadata_slot_count times</TD></TR>
				<TR><TD PORT="backup_metadata_pos">...</TD><TD PORT="backup_metadata_size">primary_geometry.metadata_max_size</TD><TD>Metadata</TD><TD PORT="backup_metadata_type">backup_metadata</TD></TR>
				<TR><TD COLSPAN="4" PORT="backup_metadata__repeat">repeat primary_geometry.metadata_slot_count times</TD></TR>
			</TABLE>>];
		}
		subgraph cluster__geometry {
			label="AndroidSuper::Geometry";
			graph[style=dotted];

			geometry__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
				<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
				<TR><TD PORT="magic_pos">0</TD><TD PORT="magic_size">4</TD><TD></TD><TD PORT="magic_type">magic</TD></TR>
				<TR><TD PORT="struct_size_pos">4</TD><TD PORT="struct_size_size">4</TD><TD>u4le</TD><TD PORT="struct_size_type">struct_size</TD></TR>
				<TR><TD PORT="checksum_pos">8</TD><TD PORT="checksum_size">32</TD><TD></TD><TD PORT="checksum_type">checksum</TD></TR>
				<TR><TD PORT="metadata_max_size_pos">40</TD><TD PORT="metadata_max_size_size">4</TD><TD>u4le</TD><TD PORT="metadata_max_size_type">metadata_max_size</TD></TR>
				<TR><TD PORT="metadata_slot_count_pos">44</TD><TD PORT="metadata_slot_count_size">4</TD><TD>u4le</TD><TD PORT="metadata_slot_count_type">metadata_slot_count</TD></TR>
				<TR><TD PORT="logical_block_size_pos">48</TD><TD PORT="logical_block_size_size">4</TD><TD>u4le</TD><TD PORT="logical_block_size_type">logical_block_size</TD></TR>
			</TABLE>>];
		}
		subgraph cluster__metadata {
			label="AndroidSuper::Metadata";
			graph[style=dotted];

			metadata__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
				<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
				<TR><TD PORT="magic_pos">0</TD><TD PORT="magic_size">4</TD><TD></TD><TD PORT="magic_type">magic</TD></TR>
				<TR><TD PORT="major_version_pos">4</TD><TD PORT="major_version_size">2</TD><TD>u2le</TD><TD PORT="major_version_type">major_version</TD></TR>
				<TR><TD PORT="minor_version_pos">6</TD><TD PORT="minor_version_size">2</TD><TD>u2le</TD><TD PORT="minor_version_type">minor_version</TD></TR>
				<TR><TD PORT="header_size_pos">8</TD><TD PORT="header_size_size">4</TD><TD>u4le</TD><TD PORT="header_size_type">header_size</TD></TR>
				<TR><TD PORT="header_checksum_pos">12</TD><TD PORT="header_checksum_size">32</TD><TD></TD><TD PORT="header_checksum_type">header_checksum</TD></TR>
				<TR><TD PORT="tables_size_pos">44</TD><TD PORT="tables_size_size">4</TD><TD>u4le</TD><TD PORT="tables_size_type">tables_size</TD></TR>
				<TR><TD PORT="tables_checksum_pos">48</TD><TD PORT="tables_checksum_size">32</TD><TD></TD><TD PORT="tables_checksum_type">tables_checksum</TD></TR>
				<TR><TD PORT="partitions_pos">80</TD><TD PORT="partitions_size">12</TD><TD>TableDescriptor</TD><TD PORT="partitions_type">partitions</TD></TR>
				<TR><TD PORT="extents_pos">92</TD><TD PORT="extents_size">12</TD><TD>TableDescriptor</TD><TD PORT="extents_type">extents</TD></TR>
				<TR><TD PORT="groups_pos">104</TD><TD PORT="groups_size">12</TD><TD>TableDescriptor</TD><TD PORT="groups_type">groups</TD></TR>
				<TR><TD PORT="block_devices_pos">116</TD><TD PORT="block_devices_size">12</TD><TD>TableDescriptor</TD><TD PORT="block_devices_type">block_devices</TD></TR>
			</TABLE>>];
			subgraph cluster__block_device {
				label="AndroidSuper::Metadata::BlockDevice";
				graph[style=dotted];

				block_device__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
					<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
					<TR><TD PORT="first_logical_sector_pos">0</TD><TD PORT="first_logical_sector_size">8</TD><TD>u8le</TD><TD PORT="first_logical_sector_type">first_logical_sector</TD></TR>
					<TR><TD PORT="alignment_pos">8</TD><TD PORT="alignment_size">4</TD><TD>u4le</TD><TD PORT="alignment_type">alignment</TD></TR>
					<TR><TD PORT="alignment_offset_pos">12</TD><TD PORT="alignment_offset_size">4</TD><TD>u4le</TD><TD PORT="alignment_offset_type">alignment_offset</TD></TR>
					<TR><TD PORT="size_pos">16</TD><TD PORT="size_size">8</TD><TD>u8le</TD><TD PORT="size_type">size</TD></TR>
					<TR><TD PORT="partition_name_pos">24</TD><TD PORT="partition_name_size">36</TD><TD>str(UTF-8)</TD><TD PORT="partition_name_type">partition_name</TD></TR>
					<TR><TD PORT="flag_slot_suffixed_pos">60</TD><TD PORT="flag_slot_suffixed_size">1b</TD><TD>BitsType1(LittleBitEndian)</TD><TD PORT="flag_slot_suffixed_type">flag_slot_suffixed</TD></TR>
					<TR><TD PORT="flags_reserved_pos">60:1</TD><TD PORT="flags_reserved_size">31b</TD><TD>b31</TD><TD PORT="flags_reserved_type">flags_reserved</TD></TR>
				</TABLE>>];
			}
			subgraph cluster__extent {
				label="AndroidSuper::Metadata::Extent";
				graph[style=dotted];

				extent__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
					<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
					<TR><TD PORT="num_sectors_pos">0</TD><TD PORT="num_sectors_size">8</TD><TD>u8le</TD><TD PORT="num_sectors_type">num_sectors</TD></TR>
					<TR><TD PORT="target_type_pos">8</TD><TD PORT="target_type_size">4</TD><TD>u4le→TargetType</TD><TD PORT="target_type_type">target_type</TD></TR>
					<TR><TD PORT="target_data_pos">12</TD><TD PORT="target_data_size">8</TD><TD>u8le</TD><TD PORT="target_data_type">target_data</TD></TR>
					<TR><TD PORT="target_source_pos">20</TD><TD PORT="target_source_size">4</TD><TD>u4le</TD><TD PORT="target_source_type">target_source</TD></TR>
				</TABLE>>];
			}
			subgraph cluster__table_descriptor {
				label="AndroidSuper::Metadata::TableDescriptor";
				graph[style=dotted];

				table_descriptor__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
					<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
					<TR><TD PORT="offset_pos">0</TD><TD PORT="offset_size">4</TD><TD>u4le</TD><TD PORT="offset_type">offset</TD></TR>
					<TR><TD PORT="num_entries_pos">4</TD><TD PORT="num_entries_size">4</TD><TD>u4le</TD><TD PORT="num_entries_type">num_entries</TD></TR>
					<TR><TD PORT="entry_size_pos">8</TD><TD PORT="entry_size_size">4</TD><TD>u4le</TD><TD PORT="entry_size_type">entry_size</TD></TR>
				</TABLE>>];
				table_descriptor__inst__table [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
					<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
					<TR><TD PORT="table_pos">(_parent.header_size + offset)</TD><TD PORT="table_size">...</TD><TD>switch (kind)</TD><TD PORT="table_type">table</TD></TR>
					<TR><TD COLSPAN="4" PORT="table__repeat">repeat num_entries times</TD></TR>
				</TABLE>>];
table_descriptor__inst__table_table_switch [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
	<TR><TD BGCOLOR="#F0F2E4">case</TD><TD BGCOLOR="#F0F2E4">type</TD></TR>
	<TR><TD>:table_kind_partitions</TD><TD PORT="case0">Partition</TD></TR>
	<TR><TD>:table_kind_extents</TD><TD PORT="case1">Extent</TD></TR>
	<TR><TD>:table_kind_groups</TD><TD PORT="case2">Group</TD></TR>
	<TR><TD>:table_kind_block_devices</TD><TD PORT="case3">BlockDevice</TD></TR>
</TABLE>>];
			}
			subgraph cluster__partition {
				label="AndroidSuper::Metadata::Partition";
				graph[style=dotted];

				partition__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
					<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
					<TR><TD PORT="name_pos">0</TD><TD PORT="name_size">36</TD><TD>str(UTF-8)</TD><TD PORT="name_type">name</TD></TR>
					<TR><TD PORT="attr_readonly_pos">36</TD><TD PORT="attr_readonly_size">1b</TD><TD>BitsType1(LittleBitEndian)</TD><TD PORT="attr_readonly_type">attr_readonly</TD></TR>
					<TR><TD PORT="attr_slot_suffixed_pos">36:1</TD><TD PORT="attr_slot_suffixed_size">1b</TD><TD>BitsType1(LittleBitEndian)</TD><TD PORT="attr_slot_suffixed_type">attr_slot_suffixed</TD></TR>
					<TR><TD PORT="attr_updated_pos">36:2</TD><TD PORT="attr_updated_size">1b</TD><TD>BitsType1(LittleBitEndian)</TD><TD PORT="attr_updated_type">attr_updated</TD></TR>
					<TR><TD PORT="attr_disabled_pos">36:3</TD><TD PORT="attr_disabled_size">1b</TD><TD>BitsType1(LittleBitEndian)</TD><TD PORT="attr_disabled_type">attr_disabled</TD></TR>
					<TR><TD PORT="attrs_reserved_pos">36:4</TD><TD PORT="attrs_reserved_size">28b</TD><TD>b28</TD><TD PORT="attrs_reserved_type">attrs_reserved</TD></TR>
					<TR><TD PORT="first_extent_index_pos">40</TD><TD PORT="first_extent_index_size">4</TD><TD>u4le</TD><TD PORT="first_extent_index_type">first_extent_index</TD></TR>
					<TR><TD PORT="num_extents_pos">44</TD><TD PORT="num_extents_size">4</TD><TD>u4le</TD><TD PORT="num_extents_type">num_extents</TD></TR>
					<TR><TD PORT="group_index_pos">48</TD><TD PORT="group_index_size">4</TD><TD>u4le</TD><TD PORT="group_index_type">group_index</TD></TR>
				</TABLE>>];
			}
			subgraph cluster__group {
				label="AndroidSuper::Metadata::Group";
				graph[style=dotted];

				group__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
					<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
					<TR><TD PORT="name_pos">0</TD><TD PORT="name_size">36</TD><TD>str(UTF-8)</TD><TD PORT="name_type">name</TD></TR>
					<TR><TD PORT="flag_slot_suffixed_pos">36</TD><TD PORT="flag_slot_suffixed_size">1b</TD><TD>BitsType1(LittleBitEndian)</TD><TD PORT="flag_slot_suffixed_type">flag_slot_suffixed</TD></TR>
					<TR><TD PORT="flags_reserved_pos">36:1</TD><TD PORT="flags_reserved_size">31b</TD><TD>b31</TD><TD PORT="flags_reserved_type">flags_reserved</TD></TR>
					<TR><TD PORT="maximum_size_pos">40</TD><TD PORT="maximum_size_size">8</TD><TD>u8le</TD><TD PORT="maximum_size_type">maximum_size</TD></TR>
				</TABLE>>];
			}
		}
	}
	android_super__inst__root:root_type -> root__seq [style=bold];
	root__seq:primary_geometry_type -> geometry__seq [style=bold];
	root__seq:backup_geometry_type -> geometry__seq [style=bold];
	geometry__seq:metadata_max_size_type -> root__seq:primary_metadata_size [color="#404040"];
	root__seq:primary_metadata_type -> metadata__seq [style=bold];
	geometry__seq:metadata_slot_count_type -> root__seq:primary_metadata__repeat [color="#404040"];
	geometry__seq:metadata_max_size_type -> root__seq:backup_metadata_size [color="#404040"];
	root__seq:backup_metadata_type -> metadata__seq [style=bold];
	geometry__seq:metadata_slot_count_type -> root__seq:backup_metadata__repeat [color="#404040"];
	metadata__seq:partitions_type -> table_descriptor__seq [style=bold];
	metadata__seq:extents_type -> table_descriptor__seq [style=bold];
	metadata__seq:groups_type -> table_descriptor__seq [style=bold];
	metadata__seq:block_devices_type -> table_descriptor__seq [style=bold];
	metadata__seq:header_size_type -> table_descriptor__inst__table:table_pos [color="#404040"];
	table_descriptor__seq:offset_type -> table_descriptor__inst__table:table_pos [color="#404040"];
	table_descriptor__inst__table:table_type -> table_descriptor__inst__table_table_switch [style=bold];
	table_descriptor__inst__table_table_switch:case0 -> partition__seq [style=bold];
	table_descriptor__inst__table_table_switch:case1 -> extent__seq [style=bold];
	table_descriptor__inst__table_table_switch:case2 -> group__seq [style=bold];
	table_descriptor__inst__table_table_switch:case3 -> block_device__seq [style=bold];
	table_descriptor__params:kind_type -> table_descriptor__inst__table:table_type [color="#404040"];
	table_descriptor__seq:num_entries_type -> table_descriptor__inst__table:table__repeat [color="#404040"];
}