APDU: Resolve some inconsistencies in handling of signed/unsigned in …

…the lengths

pythoncard/framework/apdu.py

@@ -25,6 +25,8 @@
 
 from pythoncard.framework import APDUException, ISOException, ISO7816
 
+from pythoncard.utils import u1
+
 # there can only be one (1) APDU at a time ...
 _current = None
 
@@ -115,10 +117,10 @@ def __init__(self, bytesarr):
     def __getInLengths(self):
         """ return a tuple (value, length of value) """
         if self.__buffer[ISO7816.OFFSET_LC] == 0:
-            return (self.__buffer[ISO7816.OFFSET_LC + 1] * 256 +
-                    self.__buffer[ISO7816.OFFSET_LC + 2]), 3
+            return (u1(self.__buffer[ISO7816.OFFSET_LC + 1]) * 256 +
+                    u1(self.__buffer[ISO7816.OFFSET_LC + 2])), 3
         else:
-            return self.__buffer[ISO7816.OFFSET_LC], 1
+            return u1(self.__buffer[ISO7816.OFFSET_LC]), 1
 
     def __getOutLengths(self, length):
         """ return a tuple (value, length of value) """
@@ -133,8 +135,8 @@ def __getOutLengths(self, length):
         else:
             if length != ISO7816.OFFSET_LC:
                 if self.__buffer[ISO7816.OFFSET_LC] == 0:
-                    return self.__buffer[length-1] * 256 + self.__buffer[length], 2
-            return self.__buffer[length], 1
+                    return u1(self.__buffer[length-1]) * 256 + u1(self.__buffer[length]), 2
+            return u1(self.__buffer[length]), 1
 
 
     def getBuffer(self):

pythoncard/framework/util.py

@@ -5,6 +5,8 @@
 from python.lang import ArrayIndexOutOfBoundsException
 from pythoncard.framework import JCSystem
 
+from pythoncard.utils import s1, s2
+
 def arrayCompare(src, srcOff, dest, destOff, length):
     try:
         for i in range(length):
@@ -46,7 +48,7 @@ def arrayFillNonAtomic(bArray, bOff, bLen, bValue):
 
 def makeShort(b1, b2):
     """ a short is signed ... """
-    return _signed2(((b1 << 8) & 0xFF00) | (b2 & 0xFF))
+    return s2(((b1 << 8) & 0xFF00) | (b2 & 0xFF))
 
 def getShort(bArray, bOff):
     try:
@@ -55,28 +57,10 @@ def getShort(bArray, bOff):
         raise ArrayIndexOutOfBoundsException()
 
 def setShort(bArray, bOff, sValue):
-    b1 = _signed1((sValue & 0xFF00) >> 8)
-    b2 = _signed1(sValue & 0xFF)
+    b1 = s1((sValue & 0xFF00) >> 8)
+    b2 = s1(sValue & 0xFF)
     try:
         bArray[bOff] = b1
         bArray[bOff + 1] = b2
     except IndexError:
         raise ArrayIndexOutOfBoundsException()
-
-# Taken from CAPRunner
-
-def _signed(value, depth):
-    """
-    return the signed value of the number on the specified depth
-    """
-    mask = (1 << (depth*8)) - 1
-    if value > ((1 << (depth*8)-1) - 1):
-        return -(~(value-1) & mask)
-    else:
-        return value
-
-def _signed1(value):
-    return _signed(value, 1)
-
-def _signed2(value):
-    return _signed(value, 2)

pythoncard/utils.py

@@ -12,6 +12,11 @@ def signed(value, depth):
 def s1(value):
     return signed(value, 1)
 
+def s2(value):
+    return signed(value, 2)
+
+def u1(value):
+    return value & 0xff
 
 class NotAlwaysStatic(object):
     """ This makes a function both static and not static