laforge has uploaded this change for review. ( https://gerrit.osmocom.org/c/pysim/+/35459?usp=email )

Change subject: commands: Ignore exceptions during READ while UPDATE ......................................................................

commands: Ignore exceptions during READ while UPDATE

If we are reading a file to check if we can skip the write to conserve writes, don't treat exceptions as fatal. The file may well have the access mode in a way that permits us to UPDATE but not to READ. Simply fall-back to unconditional UPDATE in this case.

Change-Id: I7bffdaa7596e63c8f0ab04a3cb3ebe12f137d3a8 --- M pySim/commands.py 1 file changed, 35 insertions(+), 7 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/pysim refs/changes/59/35459/1

diff --git a/pySim/commands.py b/pySim/commands.py index 336cf0c..d785251 100644 --- a/pySim/commands.py +++ b/pySim/commands.py @@ -279,9 +279,16 @@

# Save write cycles by reading+comparing before write if conserve: - data_current, sw = self.read_binary(ef, data_length, offset) - if data_current == data: - return None, sw + try: + data_current, sw = self.read_binary(ef, data_length, offset) + if data_current == data: + return None, sw + except Exception: + # cannot read data. This is not a fatal error, as reading is just done to + # conserve the amount of smart card writes. The access conditions of the file + # may well permit us to UPDATE but not permit us to READ. So let's ignore + # any such exception during READ. + pass

self.select_path(ef) total_data = '' @@ -363,10 +370,17 @@

# Save write cycles by reading+comparing before write if conserve: - data_current, sw = self.read_record(ef, rec_no) - data_current = data_current[0:rec_length*2] - if data_current == data: - return None, sw + try: + data_current, sw = self.read_record(ef, rec_no) + data_current = data_current[0:rec_length*2] + if data_current == data: + return None, sw + except Exception: + # cannot read data. This is not a fatal error, as reading is just done to + # conserve the amount of smart card writes. The access conditions of the file + # may well permit us to UPDATE but not permit us to READ. So let's ignore + # any such exception during READ. + pass

pdu = (self.cla_byte + 'dc%02x04%02x' % (rec_no, rec_length)) + data res = self._tp.send_apdu_checksw(pdu)