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154 lines
4.6 KiB
Python
154 lines
4.6 KiB
Python
# Copyright 2017 Martin Olejar
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from struct import unpack_from, pack
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########################################################################################################################
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# Binary Blob Constants
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########################################################################################################################
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DTB_BEGIN_NODE = 0x1
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DTB_END_NODE = 0x2
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DTB_PROP = 0x3
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DTB_NOP = 0x4
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DTB_END = 0x9
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########################################################################################################################
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# Header Class
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########################################################################################################################
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class Header:
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MIN_SIZE = 4 * 7
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MAX_SIZE = 4 * 10
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MAX_VERSION = 17
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MAGIC_NUMBER = 0xD00DFEED
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@property
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def version(self):
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return self._version
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@version.setter
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def version(self, value):
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if value > self.MAX_VERSION:
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raise ValueError("Invalid Version {}, use: 0 - 17 !".format(value))
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# update size and padding
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self._size = self.MIN_SIZE
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if value >= 2:
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self._size += 4
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if value >= 3:
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self._size += 4
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if value >= 17:
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self._size += 4
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self._padding = 8 - (self._size % 8) if self._size % 8 != 0 else 0
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self._version = value
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self.last_comp_version = value - 1
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@property
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def size(self):
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return self._size + self._padding
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@property
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def padding(self):
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return self._padding
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def __init__(self):
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# private variables
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self._version = None
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self._size = 0
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self._padding = 0
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# public variables
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self.total_size = 0
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self.off_dt_struct = 0
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self.off_dt_strings = 0
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self.off_mem_rsvmap = 0
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self.last_comp_version = 0
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# version depend variables
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self.boot_cpuid_phys = 0
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self.size_dt_strings = None
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self.size_dt_struct = None
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def __str__(self):
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return '<FDT-v{}, size: {}>'.format(self.version, self.size)
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def info(self):
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nfo = 'FDT Header:'
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nfo += '- Version: {}'.format(self.version)
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nfo += '- Size: {}'.format(self.size)
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return nfo
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def export(self) -> bytes:
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"""
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:return:
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"""
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if self.version is None:
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raise Exception("Header version must be specified !")
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blob = pack('>7I', self.MAGIC_NUMBER, self.total_size, self.off_dt_struct, self.off_dt_strings,
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self.off_mem_rsvmap, self.version, self.last_comp_version)
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if self.version >= 2:
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blob += pack('>I', self.boot_cpuid_phys)
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if self.version >= 3:
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blob += pack('>I', self.size_dt_strings)
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if self.version >= 17:
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blob += pack('>I', self.size_dt_struct)
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if self.padding:
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blob += bytes([0] * self.padding)
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return blob
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@classmethod
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def parse(cls, data: bytes, offset: int = 0):
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"""
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:param data:
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:param offset:
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"""
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if len(data) < (offset + cls.MIN_SIZE):
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raise ValueError('Data size too small !')
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header = cls()
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(magic_number,
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header.total_size,
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header.off_dt_struct,
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header.off_dt_strings,
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header.off_mem_rsvmap,
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header.version,
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header.last_comp_version) = unpack_from('>7I', data, offset)
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offset += cls.MIN_SIZE
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if magic_number != cls.MAGIC_NUMBER:
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raise Exception('Invalid Magic Number')
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if header.last_comp_version > cls.MAX_VERSION - 1:
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raise Exception('Invalid last compatible Version {}'.format(header.last_comp_version))
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if header.version >= 2:
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header.boot_cpuid_phys = unpack_from('>I', data, offset)[0]
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offset += 4
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if header.version >= 3:
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header.size_dt_strings = unpack_from('>I', data, offset)[0]
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offset += 4
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if header.version >= 17:
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header.size_dt_struct = unpack_from('>I', data, offset)[0]
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offset += 4
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return header
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