commands: add ".." notation to expand hexstrings

When updating files and records there are sometimes huge portions that
are just 0xff. Mostly this is at the end of a file or record that is not
completely used. Lets add a notation to tell PySim-shell how to fill
those sections.

Change-Id: Iedd7887bf7d706878f4a3beca8dbea456404610b
changes/18/28218/2
Philipp Maier 8 months ago
parent f16ac6acf8
commit 40ea4a4a1c
  1. 15
      pySim/commands.py
  2. 54
      pySim/utils.py

@ -23,7 +23,7 @@
from construct import *
from pySim.construct import LV
from pySim.utils import rpad, b2h, h2b, sw_match, bertlv_encode_len, Hexstr, h2i, str_sanitize
from pySim.utils import rpad, b2h, h2b, sw_match, bertlv_encode_len, Hexstr, h2i, str_sanitize, expand_hex
from pySim.exceptions import SwMatchError
@ -190,6 +190,10 @@ class SimCardCommands(object):
offset : byte offset in file from which to start writing
verify : Whether or not to verify data after write
"""
file_len = self.binary_size(ef)
data = expand_hex(data, file_len)
data_length = len(data) // 2
# Save write cycles by reading+comparing before write
@ -255,16 +259,17 @@ class SimCardCommands(object):
verify : verify data by re-reading the record
conserve : read record and compare it with data, skip write on match
"""
res = self.select_path(ef)
rec_length = self.__record_len(res)
data = expand_hex(data, rec_length)
if force_len:
# enforce the record length by the actual length of the given data input
rec_length = len(data) // 2
else:
# determine the record length from the select response of the file and pad
# the input data with 0xFF if necessary. In cases where the input data
# exceed we throw an exception.
rec_length = self.__record_len(res)
# make sure the input data is padded to the record length using 0xFF.
# In cases where the input data exceed we throw an exception.
if (len(data) // 2 > rec_length):
raise ValueError('Data length exceeds record length (expected max %d, got %d)' % (
rec_length, len(data) // 2))

@ -1225,6 +1225,60 @@ def auto_int(x):
return int(x, 0)
def expand_hex(hexstring, length):
"""Expand a given hexstring to a specified length by replacing "." or ".."
with a filler that is derived from the neighboring nibbles respective
bytes. Usually this will be the nibble respective byte before "." or
"..", execpt when the string begins with "." or "..", then the nibble
respective byte after "." or ".." is used.". In case the string cannot
be expanded for some reason, the input string is returned unmodified.
Args:
hexstring : hexstring to expand
length : desired length of the resulting hexstring.
Returns:
expanded hexstring
"""
# expand digit aligned
if hexstring.count(".") == 1:
pos = hexstring.index(".")
if pos > 0:
filler = hexstring[pos - 1]
else:
filler = hexstring[pos + 1]
missing = length * 2 - (len(hexstring) - 1)
if missing <= 0:
return hexstring
return hexstring.replace(".", filler * missing)
# expand byte aligned
elif hexstring.count("..") == 1:
if len(hexstring) % 2:
return hexstring
pos = hexstring.index("..")
if pos % 2:
return hexstring
if pos > 1:
filler = hexstring[pos - 2:pos]
else:
filler = hexstring[pos + 2:pos+4]
missing = length * 2 - (len(hexstring) - 2)
if missing <= 0:
return hexstring
return hexstring.replace("..", filler * (missing // 2))
# no change
return hexstring
class JsonEncoder(json.JSONEncoder):
"""Extend the standard library JSONEncoder with support for more types."""

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