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
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)