mirror of https://gerrit.osmocom.org/pysim
construct: avoid StreamError exceptions due to files containing all-ff
In smart cards, files/records containing all-ff means they are simply not used/initialized. Let's avoid raising exceptions when interpreting 0xff as length value and reading less bytes as value. Change-Id: I09c3cb82063fc094eb047749996a6eceff757ea2
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@ -402,7 +402,16 @@ def parse_construct(c, raw_bin_data: bytes, length: typing.Optional[int] = None,
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"""Helper function to wrap around normalize_construct() and filter_dict()."""
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if not length:
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length = len(raw_bin_data)
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parsed = c.parse(raw_bin_data, total_len=length, **context)
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try:
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parsed = c.parse(raw_bin_data, total_len=length, **context)
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except StreamError as e:
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# if the input is all-ff, this means the content is undefined. Let's avoid passing StreamError
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# exceptions in those situations (which might occur if a length field 0xff is 255 but then there's
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# actually less bytes in the remainder of the file.
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if all([v == 0xff for v in raw_bin_data]):
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return None
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else:
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raise e
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return normalize_construct(parsed)
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def build_construct(c, decoded_data, context: dict = {}):
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