1*d57664e9SAndroid Build Coastguard Worker# AAPT2 On-Disk Formats 2*d57664e9SAndroid Build Coastguard Worker- AAPT2 Container Format (extension `.apc`) 3*d57664e9SAndroid Build Coastguard Worker- AAPT2 Static Library Format (extension `.sapk`) 4*d57664e9SAndroid Build Coastguard Worker 5*d57664e9SAndroid Build Coastguard Worker## AAPT2 Container Format (extension `.apc`) 6*d57664e9SAndroid Build Coastguard WorkerThe APC format (AAPT2 Container Format) is generated by AAPT2 during the compile phase and 7*d57664e9SAndroid Build Coastguard Workerconsumed by the AAPT2 link phase. It is a simple container format for storing compiled PNGs, 8*d57664e9SAndroid Build Coastguard Workerbinary and protobuf XML, and intermediate protobuf resource tables. It also stores all associated 9*d57664e9SAndroid Build Coastguard Workermeta-data from the compile phase. 10*d57664e9SAndroid Build Coastguard Worker 11*d57664e9SAndroid Build Coastguard Worker### Format 12*d57664e9SAndroid Build Coastguard WorkerThe file starts with a simple header. All multi-byte fields are little-endian. 13*d57664e9SAndroid Build Coastguard Worker 14*d57664e9SAndroid Build Coastguard Worker| Size (in bytes) | Field | Description | 15*d57664e9SAndroid Build Coastguard Worker|:----------------|:--------------|:-----------------------------------------------------| 16*d57664e9SAndroid Build Coastguard Worker| `4` | `magic` | The magic bytes must equal `'AAPT'` or `0x54504141`. | 17*d57664e9SAndroid Build Coastguard Worker| `4` | `version` | The version of the container format. | 18*d57664e9SAndroid Build Coastguard Worker| `4` | `entry_count` | The number of entries in this container. | 19*d57664e9SAndroid Build Coastguard Worker 20*d57664e9SAndroid Build Coastguard WorkerThis is followed by `entry_count` of the following data structure. It must be aligned on a 32-bit 21*d57664e9SAndroid Build Coastguard Workerboundary, so if a previous entry ends unaligned, padding must be inserted. 22*d57664e9SAndroid Build Coastguard Worker 23*d57664e9SAndroid Build Coastguard Worker| Size (in bytes) | Field | Description | 24*d57664e9SAndroid Build Coastguard Worker|:----------------|:---------------|:----------------------------------------------------------------------------------------------------------| 25*d57664e9SAndroid Build Coastguard Worker| `4` | `entry_type` | The type of the entry. This can be one of two types: `RES_TABLE (0x00000000)` or `RES_FILE (0x00000001)`. | 26*d57664e9SAndroid Build Coastguard Worker| `8` | `entry_length` | The length of the data that follows. Do not use if `entry_type` is `RES_FILE`; this value may be wrong. | 27*d57664e9SAndroid Build Coastguard Worker| `entry_length` | `data` | The payload. The contents of this varies based on the `entry_type`. | 28*d57664e9SAndroid Build Coastguard Worker 29*d57664e9SAndroid Build Coastguard WorkerIf the `entry_type` is equal to `RES_TABLE (0x00000000)`, the `data` field contains a serialized 30*d57664e9SAndroid Build Coastguard Worker[aapt.pb.ResourceTable](Resources.proto). 31*d57664e9SAndroid Build Coastguard Worker 32*d57664e9SAndroid Build Coastguard WorkerIf the `entry_type` is equal to `RES_FILE (0x00000001)`, the `data` field contains the following: 33*d57664e9SAndroid Build Coastguard Worker 34*d57664e9SAndroid Build Coastguard Worker 35*d57664e9SAndroid Build Coastguard Worker| Size (in bytes) | Field | Description | 36*d57664e9SAndroid Build Coastguard Worker|:----------------|:-----------------|:----------------------------------------------------------------------------------------------------------| 37*d57664e9SAndroid Build Coastguard Worker| `4` | `header_size` | The size of the `header` field. | 38*d57664e9SAndroid Build Coastguard Worker| `8` | `data_size` | The size of the `data` field. | 39*d57664e9SAndroid Build Coastguard Worker| `header_size` | `header` | The serialized Protobuf message [aapt.pb.internal.CompiledFile](ResourcesInternal.proto). | 40*d57664e9SAndroid Build Coastguard Worker| `x` | `header_padding` | Up to 3 bytes of zeros, if padding is necessary to align the `data` field on a 32-bit boundary. | 41*d57664e9SAndroid Build Coastguard Worker| `data_size` | `data` | The payload, which is determined by the `type` field in the `aapt.pb.internal.CompiledFile`. This can be a PNG file, binary XML, or [aapt.pb.XmlNode](Resources.proto). | 42*d57664e9SAndroid Build Coastguard Worker| `y` | `data_padding` | Up to 3 bytes of zeros, if `data_size` is not a multiple of 4. | 43*d57664e9SAndroid Build Coastguard Worker 44*d57664e9SAndroid Build Coastguard Worker## AAPT2 Static Library Format (extension `.sapk`) 45*d57664e9SAndroid Build Coastguard Worker 46