Add Android super.img (Dynamic Partitions) format

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.

Signed-off-by: Thomas Hebb <[email protected]>

filesystem/android_super.ksy

@@ -0,0 +1,174 @@
+meta:
+  id: android_super
+  title: Android Dynamic Partitions metadata
+  application: Android
+  file-extension: img
+  license: CC0-1.0
+  ks-version: 0.8
+  endian: le
+
+doc: |
+  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.
+
+doc-ref: https://source.android.com/devices/tech/ota/dynamic_partitions/implement
+doc-ref: https://android.googlesource.com/platform/system/core/+/master/fs_mgr/liblp/include/liblp/metadata_format.h
+
+seq:
+  - id: padding
+    size: 0x1000
+    type: dummy
+
+  - id: primary_geometry
+    size: 0x1000
+    type: geometry
+
+  - id: backup_geometry
+    type: geometry
+    size: 0x1000
+
+  - id: primary_metadata
+    size: primary_geometry.metadata_max_size
+    type: metadata
+    repeat: expr
+    repeat-expr: primary_geometry.metadata_slot_count
+
+  - id: backup_metadata
+    size: primary_geometry.metadata_max_size
+    type: metadata
+    repeat: expr
+    repeat-expr: primary_geometry.metadata_slot_count
+
+types:
+  dummy: {}
+
+  geometry:
+    seq:
+      - id: magic
+        contents: [0x67, 0x44, 0x6c, 0x61]
+      - id: struct_size
+        type: u4
+      - id: checksum
+        size: 32
+      - id: metadata_max_size
+        type: u4
+      - id: metadata_slot_count
+        type: u4
+      - id: logical_block_size
+        type: u4
+
+  metadata:
+    seq:
+      - id: magic
+        contents: [0x30, 0x50, 0x4c, 0x41]
+      - id: major_version
+        type: u2
+      - id: minor_version
+        type: u2
+      - id: header_size
+        type: u4
+      - id: header_checksum
+        size: 32
+      - id: tables_size
+        type: u4
+      - id: tables_checksum
+        size: 32
+      - id: partitions
+        type: table_descriptor(0)
+      - id: extents
+        type: table_descriptor(1)
+      - id: groups
+        type: table_descriptor(2)
+      - id: block_devices
+        type: table_descriptor(3)
+
+    types:
+      table_descriptor:
+        params:
+          - id: entry_type
+            type: u8
+
+        seq:
+          - id: offset
+            type: u4
+          - id: num_entries
+            type: u4
+          - id: entry_size
+            type: u4
+
+        instances:
+          table:
+            pos: _parent.header_size + offset
+            size: entry_size
+            type:
+              switch-on: entry_type
+              cases:
+                0: partition
+                1: extent
+                2: group
+                3: block_device
+            repeat: expr
+            repeat-expr: num_entries
+
+      partition:
+        seq:
+          - id: name
+            size: 36
+            type: strz
+            encoding: UTF-8
+          - id: attributes
+            type: u4
+          - id: first_extent_index
+            type: u4
+          - id: num_extents
+            type: u4
+          - id: group_index
+            type: u4
+
+      extent:
+        seq:
+          - id: num_sectors
+            type: u8
+          - id: target_type
+            type: u4
+            enum: target_type
+          - id: target_data
+            type: u8
+          - id: target_source
+            type: u4
+
+        enums:
+          target_type:
+            0: linear
+            1: zero
+
+      group:
+        seq:
+          - id: name
+            size: 36
+            type: strz
+            encoding: UTF-8
+          - id: flags
+            type: u4
+          - id: maximum_size
+            type: u8
+
+      block_device:
+        seq:
+          - id: first_logical_sector
+            type: u8
+          - id: alignment
+            type: u4
+          - id: alignment_offset
+            type: u4
+          - id: size
+            type: u8
+          - id: partition_name
+            size: 36
+            type: strz
+            encoding: UTF-8
+          - id: flags
+            type: u4