ts_102_221: The BTLV IEs FILE SIZE and TOTAL FILE SIZE have a min length
The TLV IEs FILE SIZE and TOTAL FILE SIZE have a minimum length of 2
byte. Even when the length is in the single digit range two bytes must
be used. See also: ETSI TS 102 221, section 11.1.1.4.1 and 11.1.1.4.2
Change-Id: Ief113ce8fe3bcae2c9fb2ff4138df9ccf98d26ff
diff --git a/pySim/construct.py b/pySim/construct.py
index fcbadd8..4910a7f 100644
--- a/pySim/construct.py
+++ b/pySim/construct.py
@@ -208,10 +208,11 @@
class GreedyInteger(Construct):
"""A variable-length integer implementation, think of combining GrredyBytes with BytesInteger."""
- def __init__(self, signed=False, swapped=False):
+ def __init__(self, signed=False, swapped=False, minlen=0):
super().__init__()
self.signed = signed
self.swapped = swapped
+ self.minlen = minlen
def _parse(self, stream, context, path):
data = stream_read_entire(stream, path)
@@ -222,23 +223,30 @@
except ValueError as e:
raise IntegerError(str(e), path=path)
- def __bytes_required(self, i):
+ def __bytes_required(self, i, minlen=0):
if self.signed:
raise NotImplementedError("FIXME: Implement support for encoding signed integer")
+
+ # compute how many bytes we need
nbytes = 1
while True:
i = i >> 8
if i == 0:
- return nbytes
+ break
else:
nbytes = nbytes + 1
- # this should never happen, above loop must return eventually...
- raise IntegerError(f"value {i} is out of range")
+
+ # round up to the minimum number
+ # of bytes we anticipate
+ if nbytes < minlen:
+ nbytes = minlen
+
+ return nbytes
def _build(self, obj, stream, context, path):
if not isinstance(obj, integertypes):
raise IntegerError(f"value {obj} is not an integer", path=path)
- length = self.__bytes_required(obj)
+ length = self.__bytes_required(obj, self.minlen)
try:
data = integer2bytes(obj, length, self.signed)
except ValueError as e:
diff --git a/pySim/ts_102_221.py b/pySim/ts_102_221.py
index e7aff97..08e836c 100644
--- a/pySim/ts_102_221.py
+++ b/pySim/ts_102_221.py
@@ -80,11 +80,11 @@
# ETSI TS 102 221 11.1.1.4.2
class FileSize(BER_TLV_IE, tag=0x80):
- _construct = GreedyInteger()
+ _construct = GreedyInteger(minlen=2)
# ETSI TS 102 221 11.1.1.4.2
class TotalFileSize(BER_TLV_IE, tag=0x81):
- _construct = GreedyInteger()
+ _construct = GreedyInteger(minlen=2)
# ETSI TS 102 221 11.1.1.4.3
class FileDescriptor(BER_TLV_IE, tag=0x82):