1 files changed, 50 insertions, 22 deletions

diff --git a/pyasn1/codec/cer/decoder.py b/pyasn1/codec/cer/decoder.py
index 3e86fd0..0a92b26 100644
--- a/pyasn1/codec/cer/decoder.py
+++ b/pyasn1/codec/cer/decoder.py
@@ -5,60 +5,88 @@
 # License: http://snmplabs.com/pyasn1/license.html
 #
 from pyasn1 import error
+from pyasn1.codec.streaming import readFromStream
 from pyasn1.codec.ber import decoder
 from pyasn1.compat.octets import oct2int
 from pyasn1.type import univ
 
-__all__ = ['decode']
+__all__ = ['decode', 'StreamingDecoder']
 
+SubstrateUnderrunError = error.SubstrateUnderrunError
 
-class BooleanDecoder(decoder.AbstractSimpleDecoder):
+
+class BooleanPayloadDecoder(decoder.AbstractSimplePayloadDecoder):
     protoComponent = univ.Boolean(0)
 
     def valueDecoder(self, substrate, asn1Spec,
                      tagSet=None, length=None, state=None,
                      decodeFun=None, substrateFun=None,
                      **options):
-        head, tail = substrate[:length], substrate[length:]
-        if not head or length != 1:
+
+        if length != 1:
             raise error.PyAsn1Error('Not single-octet Boolean payload')
-        byte = oct2int(head[0])
+
+        for chunk in readFromStream(substrate, length, options):
+            if isinstance(chunk, SubstrateUnderrunError):
+                yield chunk
+
+        byte = oct2int(chunk[0])
+
         # CER/DER specifies encoding of TRUE as 0xFF and FALSE as 0x0, while
         # BER allows any non-zero value as TRUE; cf. sections 8.2.2. and 11.1 
         # in https://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf
         if byte == 0xff:
             value = 1
+
         elif byte == 0x00:
             value = 0
+
         else:
             raise error.PyAsn1Error('Unexpected Boolean payload: %s' % byte)
-        return self._createComponent(asn1Spec, tagSet, value, **options), tail
+
+        yield self._createComponent(asn1Spec, tagSet, value, **options)
+
 
 # TODO: prohibit non-canonical encoding
-BitStringDecoder = decoder.BitStringDecoder
-OctetStringDecoder = decoder.OctetStringDecoder
-RealDecoder = decoder.RealDecoder
-
-tagMap = decoder.tagMap.copy()
-tagMap.update(
-    {univ.Boolean.tagSet: BooleanDecoder(),
-     univ.BitString.tagSet: BitStringDecoder(),
-     univ.OctetString.tagSet: OctetStringDecoder(),
-     univ.Real.tagSet: RealDecoder()}
+BitStringPayloadDecoder = decoder.BitStringPayloadDecoder
+OctetStringPayloadDecoder = decoder.OctetStringPayloadDecoder
+RealPayloadDecoder = decoder.RealPayloadDecoder
+
+TAG_MAP = decoder.TAG_MAP.copy()
+TAG_MAP.update(
+    {univ.Boolean.tagSet: BooleanPayloadDecoder(),
+     univ.BitString.tagSet: BitStringPayloadDecoder(),
+     univ.OctetString.tagSet: OctetStringPayloadDecoder(),
+     univ.Real.tagSet: RealPayloadDecoder()}
 )
 
-typeMap = decoder.typeMap.copy()
+TYPE_MAP = decoder.TYPE_MAP.copy()
 
 # Put in non-ambiguous types for faster codec lookup
-for typeDecoder in tagMap.values():
+for typeDecoder in TAG_MAP.values():
     if typeDecoder.protoComponent is not None:
         typeId = typeDecoder.protoComponent.__class__.typeId
-        if typeId is not None and typeId not in typeMap:
-            typeMap[typeId] = typeDecoder
+        if typeId is not None and typeId not in TYPE_MAP:
+            TYPE_MAP[typeId] = typeDecoder
+
+
+class SingleItemDecoder(decoder.SingleItemDecoder):
+    __doc__ = decoder.SingleItemDecoder.__doc__
+
+    TAG_MAP = TAG_MAP
+    TYPE_MAP = TYPE_MAP
+
+
+class StreamingDecoder(decoder.StreamingDecoder):
+    __doc__ = decoder.StreamingDecoder.__doc__
+
+    SINGLE_ITEM_DECODER = SingleItemDecoder
 
 
 class Decoder(decoder.Decoder):
-    pass
+    __doc__ = decoder.Decoder.__doc__
+
+    STREAMING_DECODER = StreamingDecoder
 
 
 #: Turns CER octet stream into an ASN.1 object.
@@ -111,4 +139,4 @@ class Decoder(decoder.Decoder):
 #:    SequenceOf:
 #:     1 2 3
 #:
-decode = Decoder(tagMap, decoder.typeMap)
+decode = Decoder()