dexter has uploaded this change for review. ( 
https://gerrit.osmocom.org/c/pysim/+/34884?usp=email )


Change subject: pySim-shell: don't get trapped in applications without file 
system
......................................................................

pySim-shell: don't get trapped in applications without file system

When we traverse the file system, we may also end up selecting
applications (ADF), which do not support an USIM/ISIM like file system.
This will leave us without the ability to select the MF (or any other
file) again. The only way out is to select the ISIM or USIM application
again to get the access to the file system again.

Related: OS#5418
Change-Id: Ia2fdd65f430c07acb1afdaf265d24c6928b654e0
---
M pySim-shell.py
1 file changed, 42 insertions(+), 2 deletions(-)



  git pull ssh://gerrit.osmocom.org:29418/pysim refs/changes/84/34884/1

diff --git a/pySim-shell.py b/pySim-shell.py
index 8a1ad01..2368f95 100755
--- a/pySim-shell.py
+++ b/pySim-shell.py
@@ -55,7 +55,7 @@
 from pySim.utils import sanitize_pin_adm, tabulate_str_list, 
boxed_heading_str, Hexstr, dec_iccid
 from pySim.card_handler import CardHandler, CardHandlerAuto

-from pySim.filesystem import CardDF, CardADF, CardModel, CardApplication
+from pySim.filesystem import CardMF, CardDF, CardADF, CardModel, 
CardApplication
 from pySim.runtime import RuntimeState
 from pySim.profile import CardProfile
 from pySim.cdma_ruim import CardProfileRUIM
@@ -599,7 +599,31 @@
                 # below, so we must not move up.
                 if skip_df == False:
                     self.walk(indent + 1, action_ef, action_df, context, 
**kwargs)
-                    fcp_dec = self._cmd.lchan.select("..", self._cmd)
+
+                    parent = 
self._cmd.lchan.selected_file.get_selectables()[".."]
+                    df = self._cmd.lchan.selected_file
+                    if isinstance(parent, CardMF) and (df.name not in [ 
"ADF.USIM", "ADF.ISIM"]):
+                        # Not every application that may be present on a 
GlobalPlatform card will support the SELECT
+                        # command as we know it from ETSI TS 102 221, section 
11.1.1. In fact the only subset of
+                        # SELECT we may rely on is the OPEN SELECT command as 
specified in GlobalPlatform Card
+                        # Specification, section 11.9. Unfortunately the OPEN 
SELECT command only supports the
+                        # "select by name" method, which means we can only 
select an application and not a file.
+                        # The consequence of this is that we may get trapped 
in an application that does not have
+                        # ISIM/USIM like file system support and the only way 
to leave that application is to select
+                        # an ISIM/USIM application in order to get the file 
system access back.
+                        #
+                        # To automatize this escape-route while traversing the 
file system we will check whether
+                        # the parent file is the MF. When this is the case and 
the selected ADF is not ADF.ISIM or
+                        # ADF.USIM, we will select ADF.USIM or ADF.ISIM 
(depending on what is available) and from
+                       # from there we will then select the MF.
+                        for app in parent.applications:
+                            if app in [ "a0000000871002", "a0000000871004"]:
+                                adf_xsim = app
+                        self._cmd.lchan.select(adf_xsim, self._cmd)
+                        self._cmd.lchan.select("MF", self._cmd)
+                    else:
+                        # Normal DF/ADF selection
+                        fcp_dec = self._cmd.lchan.select("..", self._cmd)

             elif action_ef:
                 df_before_action = self._cmd.lchan.selected_file

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Gerrit-Project: pysim
Gerrit-Branch: master
Gerrit-Change-Id: Ia2fdd65f430c07acb1afdaf265d24c6928b654e0
Gerrit-Change-Number: 34884
Gerrit-PatchSet: 1
Gerrit-Owner: dexter <pma...@sysmocom.de>
Gerrit-MessageType: newchange

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