# Copyright 2024 Google LLC # # Licensed under the Apache License, Version 2.0 (the "License"); # you may not use this file except in compliance with the License. # You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. import struct import uuid class PebbleAppHeader(object): MAGIC = 'PBLAPP\x00\x00' # 10 bytes HEADER_STRUCT_DEFINITION = [ '8s', # header '2B', # struct version ] HEADER_STRUCT = struct.Struct(''.join(HEADER_STRUCT_DEFINITION)) # 116 bytes V1_STRUCT_VERSION = (0x08, 0x01) V1_STRUCT_DEFINTION = [ # format, name, deserialization transform, serialization transform ('B', 'sdk_version_major', None, None), ('B', 'sdk_version_minor', None, None), ('B', 'app_version_major', None, None), ('B', 'app_version_minor', None, None), ('H', 'app_size', None, None), ('I', 'offset', None, None), ('I', 'crc', None, None), ('32s', 'app_name', lambda bytes: bytes.rstrip('\0'), None), ('32s', 'company_name', lambda bytes: bytes.rstrip('\0'), None), ('I', 'icon_resource_id', None, None), ('I', 'symbol_table_addr', None, None), ('I', 'flags', None, None), ('I', 'relocation_list_index', None, None), ('I', 'num_relocation_entries', None, None), ('16s', 'uuid', lambda s: uuid.UUID(bytes=s), lambda u: u.bytes), ] # 120 bytes V2_STRUCT_VERSION = (0x10, 0x00) V2_STRUCT_DEFINTION = list(V1_STRUCT_DEFINTION) del V2_STRUCT_DEFINTION[12] # relocation list was dropped in v2.x V2_STRUCT_DEFINTION += [ ('I', 'resource_crc', None, None), ('I', 'resource_timestamp', None, None), ('H', 'virtual_size', None, None), ] V2_HEADER_LENGTH = 10 + 120 DEFINITION_MAP = { V1_STRUCT_VERSION: V1_STRUCT_DEFINTION, V2_STRUCT_VERSION: V2_STRUCT_DEFINTION, } @classmethod def get_def_and_struct(cls, struct_version): definition = cls.DEFINITION_MAP.get(struct_version) if not definition: raise Exception("Unsupported " "struct version %s" % str(struct_version)) fmt = '<' + reduce(lambda s, t: s + t[0], definition, '') s = struct.Struct(fmt) return definition, s @classmethod def deserialize(cls, app_bin): header_size = cls.HEADER_STRUCT.size header = app_bin[0:header_size] values = cls.HEADER_STRUCT.unpack(header) struct_version = (values[1], values[2]) info = { 'sentinel': values[0], 'struct_version_major': struct_version[0], 'struct_version_minor': struct_version[1], } if info['sentinel'] != cls.MAGIC: raise Exception('This is not a pebble watchapp') definition, s = cls.get_def_and_struct(struct_version) values = s.unpack(app_bin[header_size:header_size + s.size]) for value, elem in zip(values, definition): field_name = elem[1] transform = elem[2] info[field_name] = value if not transform else transform(value) return info def serialize(self): struct_version = (self._info['struct_version_major'], self._info['struct_version_minor']) header = PebbleAppHeader.HEADER_STRUCT.pack(PebbleAppHeader.MAGIC, *struct_version) definition, s = self.__class__.get_def_and_struct(struct_version) def map_args(elem): value = self._info[elem[1]] transform = elem[3] return value if not transform else transform(value) args = map(map_args, definition) return header + s.pack(*args) def __init__(self, app_bin_bytes): self._info = PebbleAppHeader.deserialize(app_bin_bytes) def __getattr__(self, name): value = self._info.get(name) if value is None: raise Exception("Unknown field %s" % name) return value def __setattr__(self, name, value): if name == '_info': super(PebbleAppHeader, self).__setattr__(name, value) self._info[name] = value def __repr__(self): return self._info.__repr__() def __str__(self): return self.__repr__() if __name__ == '__main__': import argparse import pprint parser = argparse.ArgumentParser() parser.add_argument('bin_file') args = parser.parse_args() with open(args.bin_file, 'rb') as f: app_info = PebbleAppHeader.deserialize(f.read()) pprint.pprint(app_info)