fixed offset checking for empty files

virtualsmartcard/src/vpicc/virtualsmartcard/SmartcardFilesystem.py

@@ -699,7 +699,7 @@ class MF(DF):
     def dataUnitsDecodePlain(self, p1, p2, data):
         """
         Decodes 'p1', 'p2' and 'data' from a data unit command (i. e.
-        read/write/update/search/erase binary) with *odd* instruction code.
+        read/write/update/search/erase binary) with *even* instruction code.
         
         :returns: the specified TransparentStructureEF, a list of offsets and a
             list of data strings.
@@ -725,7 +725,7 @@ class MF(DF):
     def dataUnitsDecodeEncapsulated(self, p1, p2, data):
         """
         Decodes 'p1', 'p2' and 'data' from a data unit command (i. e.
-        read/write/update/search/erase binary) with *even* instruction code.
+        read/write/update/search/erase binary) with *odd* instruction code.
         
         :returns the specified TransparentStructureEF, a list of offsets and a
             list of data strings.
@@ -1376,6 +1376,9 @@ class TransparentStructureEF(EF):
         """Returns the string of decrypted data beginning at 'offset'."""
         data = self.data
 
+        if offset == 0:
+            return data
+        else:
             if offset + 1 > len(data):
                 raise SwError(SW["ERR_OFFSETOUTOFFILE"])
 
@@ -1587,10 +1590,11 @@ class RecordStructureEF(EF):
         records  = self.__getRecords(num_id, reference)
         result   = []
         for r in records:
-            result.append(r.data[offset:])
             if offset == 0:
-                pass
+                result.append(r.data)
-            elif offset > 0 and offset > len(r.data):
+            else:
+                result.append(r.data[offset:])
+                if offset > 0 and offset > len(r.data):
                     offset -= len(r.data)
                 else:
                     offset = 0