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57 lines
1.6 KiB
57 lines
1.6 KiB
#
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# Copyright (C) 2018 The Android Open Source Project
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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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#
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"""This file contains ELF utility functions."""
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def ByteToInt(obj):
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"""Converts an element of a bytes object to an integer."""
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return obj if isinstance(obj, int) else ord(obj)
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def BytesToString(obj):
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"""Converts bytes to a python3 string."""
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return obj if isinstance(obj, str) else obj.decode("utf-8")
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def DecodeSLEB128(data, begin_offset=0):
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"""Decode one int64 from SLEB128 encoded bytes.
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Args:
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data: A bytes object to decode.
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begin_offset: An integer, offset in data to start decode from.
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Returns:
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A tuple (value, num), the decoded value and number of consumed bytes.
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Raises:
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IndexError: String index out of range.
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"""
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cur = begin_offset
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value = 0
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shift = 0
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while True:
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try:
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byte, cur = ByteToInt(data[cur]), cur + 1
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except IndexError:
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raise
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value |= (byte & 0x7F) << shift
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shift += 7
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if byte & 0x80 == 0:
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break
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if byte & 0x40:
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value |= (-1) << shift
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return value, cur - begin_offset
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