1 files changed, 174 insertions, 0 deletions
diff --git a/lib/Crypto/Util/py3compat.py b/lib/Crypto/Util/py3compat.py
new file mode 100644
index 0000000..3608357
--- /dev/null
+++ b/lib/Crypto/Util/py3compat.py
@@ -0,0 +1,174 @@
+# -*- coding: utf-8 -*-
+#
+#  Util/py3compat.py : Compatibility code for handling Py3k / Python 2.x
+#
+# Written in 2010 by Thorsten Behrens
+#
+# ===================================================================
+# The contents of this file are dedicated to the public domain.  To
+# the extent that dedication to the public domain is not available,
+# everyone is granted a worldwide, perpetual, royalty-free,
+# non-exclusive license to exercise all rights associated with the
+# contents of this file for any purpose whatsoever.
+# No rights are reserved.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+# ===================================================================
+
+"""Compatibility code for handling string/bytes changes from Python 2.x to Py3k
+
+In Python 2.x, strings (of type ''str'') contain binary data, including encoded
+Unicode text (e.g. UTF-8).  The separate type ''unicode'' holds Unicode text.
+Unicode literals are specified via the u'...' prefix.  Indexing or slicing
+either type always produces a string of the same type as the original.
+Data read from a file is always of '''str'' type.
+
+In Python 3.x, strings (type ''str'') may only contain Unicode text. The u'...'
+prefix and the ''unicode'' type are now redundant.  A new type (called
+''bytes'') has to be used for binary data (including any particular
+''encoding'' of a string).  The b'...' prefix allows one to specify a binary
+literal.  Indexing or slicing a string produces another string.  Slicing a byte
+string produces another byte string, but the indexing operation produces an
+integer.  Data read from a file is of '''str'' type if the file was opened in
+text mode, or of ''bytes'' type otherwise.
+
+Since PyCrypto aims at supporting both Python 2.x and 3.x, the following helper
+functions are used to keep the rest of the library as independent as possible
+from the actual Python version.
+
+In general, the code should always deal with binary strings, and use integers
+instead of 1-byte character strings.
+
+b(s)
+    Take a text string literal (with no prefix or with u'...' prefix) and
+    make a byte string.
+bchr(c)
+    Take an integer and make a 1-character byte string.
+bord(c)
+    Take the result of indexing on a byte string and make an integer.
+tobytes(s)
+    Take a text string, a byte string, or a sequence of character taken from
+    a byte string and make a byte string.
+"""
+
+import sys
+import abc
+
+
+if sys.version_info[0] == 2:
+    def b(s):
+        return s
+    def bchr(s):
+        return chr(s)
+    def bstr(s):
+        return str(s)
+    def bord(s):
+        return ord(s)
+    def tobytes(s, encoding="latin-1"):
+        if isinstance(s, unicode):
+            return s.encode(encoding)
+        elif isinstance(s, str):
+            return s
+        elif isinstance(s, bytearray):
+            return bytes(s)
+        elif isinstance(s, memoryview):
+            return s.tobytes()
+        else:
+            return ''.join(s)
+    def tostr(bs):
+        return bs
+    def byte_string(s):
+        return isinstance(s, str)
+
+    from StringIO import StringIO
+    BytesIO = StringIO
+
+    from sys import maxint
+
+    iter_range = xrange
+
+    def is_native_int(x):
+        return isinstance(x, (int, long))
+
+    def is_string(x):
+        return isinstance(x, basestring)
+
+    def is_bytes(x):
+        return isinstance(x, str) or \
+                isinstance(x, bytearray) or \
+                isinstance(x, memoryview)
+
+    ABC = abc.ABCMeta('ABC', (object,), {'__slots__': ()})
+
+    FileNotFoundError = IOError
+
+else:
+    def b(s):
+       return s.encode("latin-1") # utf-8 would cause some side-effects we don't want
+    def bchr(s):
+        return bytes([s])
+    def bstr(s):
+        if isinstance(s,str):
+            return bytes(s,"latin-1")
+        else:
+            return bytes(s)
+    def bord(s):
+        return s
+    def tobytes(s, encoding="latin-1"):
+        if isinstance(s, bytes):
+            return s
+        elif isinstance(s, bytearray):
+            return bytes(s)
+        elif isinstance(s,str):
+            return s.encode(encoding)
+        elif isinstance(s, memoryview):
+            return s.tobytes()
+        else:
+            return bytes([s])
+    def tostr(bs):
+        return bs.decode("latin-1")
+    def byte_string(s):
+        return isinstance(s, bytes)
+
+    from io import BytesIO
+    from io import StringIO
+    from sys import maxsize as maxint
+
+    iter_range = range
+
+    def is_native_int(x):
+        return isinstance(x, int)
+
+    def is_string(x):
+        return isinstance(x, str)
+
+    def is_bytes(x):
+        return isinstance(x, bytes) or \
+                isinstance(x, bytearray) or \
+                isinstance(x, memoryview)
+
+    from abc import ABC
+
+    FileNotFoundError = FileNotFoundError
+
+
+def _copy_bytes(start, end, seq):
+    """Return an immutable copy of a sequence (byte string, byte array, memoryview)
+    in a certain interval [start:seq]"""
+
+    if isinstance(seq, memoryview):
+        return seq[start:end].tobytes()
+    elif isinstance(seq, bytearray):
+        return bytes(seq[start:end])
+    else:
+        return seq[start:end]
+
+del sys
+del abc