AB升级(5):payload结构解析

├── care_map.pb
├── META-INF
│   └── com
│       └── android
│           ├── metadata 
│           └── otacert  // release key的公钥，用来对ota包做签名验证
├── payload.bin
└── payload_properties.txt

FILE_HASH=clGjz1kJ/Toxcax0Ap8d2cCVupI1xoBBXgqOzNK+IeQ=
FILE_SIZE=1345770359
METADATA_HASH=EG0gbI1eQ5PCQhcOovjiP8zK1H14T6CL8znOwAnQRnE=
METADATA_SIZE=98416

ota-property-files=payload_metadata.bin:1808:98683,payload.bin:1808:1345770359,payload_properties.txt:1345772225:155,care_map.pb:677:1084,metadata:69:561            
ota-required-cache=0
ota-streaming-property-files=payload.bin:1808:1345770359,payload_properties.txt:1345772225:155,care_map.pb:677:1084,metadata:69:561              
ota-type=AB
post-build=xxx
post-build-incremental=1640652245
post-sdk-level=30
post-security-patch-level=2021-10-05
post-timestamp=1640652162
pre-device=xxx

system/update_engine/update_metadata.proto

struct delta_update_file {
  char magic[4] = "CrAU";
  uint64 file_format_version;  // payload major version
  uint64 manifest_size;  // Size of protobuf DeltaArchiveManifest

  // Only present if format_version >= 2:
  uint32 metadata_signature_size;

  // The DeltaArchiveManifest protobuf serialized, not compressed.
  char manifest[manifest_size];

  // The signature of the metadata (from the beginning of the payload up to
  // this location, not including the signature itself). This is a serialized
  // Signatures message.
  char metadata_signature_message[metadata_signature_size];

  // Data blobs for files, no specific format. The specific offset
  // and length of each data blob is recorded in the DeltaArchiveManifest.
  struct {
    char data[];
  } blobs[];

  // The signature of the entire payload, everything up to this location,
  // except that metadata_signature_message is skipped to simplify signing
  // process. These two are not signed:
  uint64 payload_signatures_message_size;
  // This is a serialized Signatures message.
  char payload_signatures_message[payload_signatures_message_size];
};

message DeltaArchiveManifest {
  // Only present in major version = 1. List of install operations for the
  // kernel and rootfs partitions. For major version = 2 see the |partitions|
  // field.
  repeated InstallOperation install_operations = 1;
  repeated InstallOperation kernel_install_operations = 2;

  // (At time of writing) usually 4096
  optional uint32 block_size = 3 [default = 4096];

  // If signatures are present, the offset into the blobs, generally
  // tacked onto the end of the file, and the length. We use an offset
  // rather than a bool to allow for more flexibility in future file formats.
  // If either is absent, it means signatures aren't supported in this
  // file.
  optional uint64 signatures_offset = 4;
  optional uint64 signatures_size = 5;

  // Only present in major version = 1. Partition metadata used to validate the
  // update. For major version = 2 see the |partitions| field.
  optional PartitionInfo old_kernel_info = 6;
  optional PartitionInfo new_kernel_info = 7;
  optional PartitionInfo old_rootfs_info = 8;
  optional PartitionInfo new_rootfs_info = 9;

  // old_image_info will only be present for delta images.
  optional ImageInfo old_image_info = 10;

  optional ImageInfo new_image_info = 11;

  // The minor version, also referred as "delta version", of the payload.
  // Minor version 0 is full payload, everything else is delta payload.
  optional uint32 minor_version = 12 [default = 0];

  // Only present in major version >= 2. List of partitions that will be
  // updated, in the order they will be updated. This field replaces the
  // |install_operations|, |kernel_install_operations| and the
  // |{old,new}_{kernel,rootfs}_info| fields used in major version = 1. This
  // array can have more than two partitions if needed, and they are identified
  // by the partition name.
  repeated PartitionUpdate partitions = 13;

  // The maximum timestamp of the OS allowed to apply this payload.
  // Can be used to prevent downgrading the OS.
  optional int64 max_timestamp = 14;

  // Metadata related to all dynamic partitions.
  optional DynamicPartitionMetadata dynamic_partition_metadata = 15;
}

python3 payload_dumper.py -h
usage: payload_dumper.py [-h] [--out OUT] [--diff] [--old OLD]
                         [--images IMAGES]
                         payloadfile

OTA payload dumper

positional arguments:
  payloadfile      payload file name

optional arguments:
  -h, --help       show this help message and exit
  --out OUT        output directory (defaul: output)
  --diff           extract differential OTA, you need put original images to
                   old dir
  --old OLD        directory with original images for differential OTA
                   (defaul: old)
  --images IMAGES  images to extract (default: empty)

python3 payload_dumper.py '/work/update/payload.bin' 
Processing boot partition................Done
Processing system partition................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................Done
Processing vendor partition...........................................................................................................................................................Done
Processing preloader partition.Done
Processing md1img partition............Done
Processing md1dsp partition....Done
Processing spmfw partition.Done
Processing scp partition.Done
Processing sspm partition.Done
Processing gz partition.Done
Processing lk partition.Done
Processing dtbo partition.Done
Processing tee partition.Done
Processing vbmeta partition.Done
Processing vbmeta_system partition.Done
Processing vbmeta_vendor partition.Done
Processing product partition................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................Done

├── output
│   ├── boot.img
│   ├── dtbo.img
│   ├── gz.img
│   ├── lk.img
│   ├── md1dsp.img
│   ├── md1img.img
│   ├── preloader.img
│   ├── product.img
│   ├── scp.img
│   ├── spmfw.img
│   ├── sspm.img
│   ├── system.img
│   ├── tee.img
│   ├── vbmeta.img
│   ├── vbmeta_system.img
│   ├── vbmeta_vendor.img
│   └── vendor.img
├── payload_dumper.py