[M] Change in ...pyosmocom[master]: construct: allow stripping of leading zeros with StripTrailerAdapter

dexter has uploaded this change for review. ( https://gerrit.osmocom.org/c/python/pyosmocom/+/39193?usp=email ) Change subject: construct: allow stripping of leading zeros with StripTrailerAdapter ...................................................................... construct: allow stripping of leading zeros with StripTrailerAdapter The class StripTrailerAdapter is currently only able to strip zeros at the end of an integer. What it can not do is stripping leading zeros. Let's add a parameter for that and extend the unittests accordingly. Related: OS#6679 Change-Id: I1a9fff17abbbef0c5f6d45f58198debfa12e78b6 --- M src/osmocom/construct.py M tests/test_construct.py 2 files changed, 59 insertions(+), 6 deletions(-) git pull ssh://gerrit.osmocom.org:29418/python/pyosmocom refs/changes/93/39193/1 diff --git a/src/osmocom/construct.py b/src/osmocom/construct.py index 1f5bd45..dd92165 100644 --- a/src/osmocom/construct.py +++ b/src/osmocom/construct.py @@ -420,19 +420,23 @@ where you have a bit-mask that may have 1, 2 or 3 bytes, depending on whether or not any of the LSBs are actually set. """ - def __init__(self, subcon, total_length:int, default_value=b'\x00', min_len=1, steps:[int]=[]): + def __init__(self, subcon, total_length:int, default_value=b'\x00', min_len=1, steps:[int]=[], reverse:bool = False): super().__init__(subcon) assert len(default_value) == 1 self.total_length = total_length self.default_value = default_value self.min_len = min_len self.steps = steps + self.reverse = reverse def _decode(self, obj, context, path): assert isinstance(obj, bytes) # pad with suppressed/missing bytes if len(obj) < self.total_length: - obj += self.default_value * (self.total_length - len(obj)) + if self.reverse: + obj = self.default_value * (self.total_length - len(obj)) + obj + else: + obj += self.default_value * (self.total_length - len(obj)) return int.from_bytes(obj, 'big') def _encode(self, obj, context, path): @@ -441,10 +445,16 @@ # remove trailing bytes if they are zero obj_step_aligned = obj - while len(obj) > self.min_len and obj[-1] == self.default_value[0]: - obj = obj[:-1] - if len(obj) in self.steps: - obj_step_aligned = obj + if self.reverse: + while len(obj) > self.min_len and obj[0] == self.default_value[0]: + obj = obj[1:] + if len(obj) in self.steps: + obj_step_aligned = obj + else: + while len(obj) > self.min_len and obj[-1] == self.default_value[0]: + obj = obj[:-1] + if len(obj) in self.steps: + obj_step_aligned = obj if self.steps == []: return obj diff --git a/tests/test_construct.py b/tests/test_construct.py index e4234db..4fb1a71 100755 --- a/tests/test_construct.py +++ b/tests/test_construct.py @@ -101,6 +101,11 @@ final_application=0x0200, global_service=0x0100, receipt_generation=0x80, ciphered_load_file_data_block=0x40, contactless_activation=0x20, contactless_self_activation=0x10) + IntegerSteps = StripTrailerAdapter(GreedyBytes, 4, steps = [2,4]) + Integer = StripTrailerAdapter(GreedyBytes, 4) + IntegerStepsReverse = StripTrailerAdapter(GreedyBytes, 4, steps = [2,4], reverse = True) + IntegerReverse = StripTrailerAdapter(GreedyBytes, 4, reverse = True) + examples = ['00', '80', '8040', '400010'] def test_encdec(self): for e in self.examples: @@ -108,6 +113,44 @@ reenc = self.Privileges.build(dec) self.assertEqual(e, b2h(reenc)) + def test_encdec_integer(self): + enc = self.IntegerSteps.build(0x10000000) + self.assertEqual(b2h(enc), '1000') + enc = self.IntegerSteps.build(0x10200000) + self.assertEqual(b2h(enc), '1020') + enc = self.IntegerSteps.build(0x10203000) + self.assertEqual(b2h(enc), '10203000') + enc = self.IntegerSteps.build(0x10203040) + self.assertEqual(b2h(enc), '10203040') + + enc = self.Integer.build(0x10000000) + self.assertEqual(b2h(enc), '10') + enc = self.Integer.build(0x10200000) + self.assertEqual(b2h(enc), '1020') + enc = self.Integer.build(0x10203000) + self.assertEqual(b2h(enc), '102030') + enc = self.Integer.build(0x10203040) + self.assertEqual(b2h(enc), '10203040') + + def test_encdec_integer_reverse(self): + enc = self.IntegerStepsReverse.build(0x40) + self.assertEqual(b2h(enc), '0040') + enc = self.IntegerStepsReverse.build(0x3040) + self.assertEqual(b2h(enc), '3040') + enc = self.IntegerStepsReverse.build(0x203040) + self.assertEqual(b2h(enc), '00203040') + enc = self.IntegerStepsReverse.build(0x10203040) + self.assertEqual(b2h(enc), '10203040') + + enc = self.IntegerReverse.build(0x40) + self.assertEqual(b2h(enc), '40') + enc = self.IntegerReverse.build(0x3040) + self.assertEqual(b2h(enc), '3040') + enc = self.IntegerReverse.build(0x203040) + self.assertEqual(b2h(enc), '203040') + enc = self.IntegerReverse.build(0x10203040) + self.assertEqual(b2h(enc), '10203040') + def test_enc(self): enc = self.Privileges.build({'dap_verification' : True}) self.assertEqual(b2h(enc), '40') -- To view, visit https://gerrit.osmocom.org/c/python/pyosmocom/+/39193?usp=email To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings?usp=email Gerrit-MessageType: newchange Gerrit-Project: python/pyosmocom Gerrit-Branch: master Gerrit-Change-Id: I1a9fff17abbbef0c5f6d45f58198debfa12e78b6 Gerrit-Change-Number: 39193 Gerrit-PatchSet: 1 Gerrit-Owner: dexter &lt;pmaier(a)sysmocom.de&gt;