From 297667fab5c13886d82b037e74c84459f52e829c Mon Sep 17 00:00:00 2001
From: Victor Wagner <vitus@wagner.pp.ru>
Date: Thu, 30 Oct 2014 23:25:50 +0300
Subject: [PATCH] Addedet length parameter to Digest.update

---
 ctypescrypto/digest.py | 14 +++++++++++---
 tests/testdigest.py    | 42 +++++++++++++++++++++++++++++++++++++-----
 2 files changed, 48 insertions(+), 8 deletions(-)

diff --git a/ctypescrypto/digest.py b/ctypescrypto/digest.py
index df4e580..0098ab4 100644
--- a/ctypescrypto/digest.py
+++ b/ctypescrypto/digest.py
@@ -81,15 +81,23 @@ class Digest:
 	def __del__(self):
 		self._clean_ctx()
 
-	def update(self, data):
+	def update(self, data, length=None):
 		"""
-			Hashes given byte string as data
+			Hashes given byte string 
+
+			@param data - string to hash
+			@param length - if not specifed, entire string is hashed,
+					otherwise only first length bytes
 		"""
 		if self.digest_finalized:
 			raise DigestError, "No updates allowed"
 		if type(data) != type(""):
 			raise TypeError, "A string is expected"
-		result = libcrypto.EVP_DigestUpdate(self.ctx, c_char_p(data), len(data))
+		if length is None:
+			length=len(data)
+		elif length> len(data):
+			raise ValueError("Specified length is greater than length of data")
+		result = libcrypto.EVP_DigestUpdate(self.ctx, c_char_p(data), length)
 		if result != 1:
 			raise DigestError, "Unable to update digest"
 		
diff --git a/tests/testdigest.py b/tests/testdigest.py
index 4c4b4ed..e840080 100644
--- a/tests/testdigest.py
+++ b/tests/testdigest.py
@@ -38,23 +38,52 @@ class TestDigestType(unittest.TestCase):
 
 class TestIface(unittest.TestCase):
 	""" Test all methods with one algorithms """
+	msg="A quick brown fox jumps over the lazy dog."
+	dgst="00CFFE7312BF9CA73584F24BDF7DF1D028340397"
 	def test_cons(self):
 		md=digest.DigestType("sha1")
 		dgst=digest.Digest(md)
-		dgst.update("A quick brown fox jumps over the lazy dog.")
+		dgst.update(self.msg)
 		self.assertEqual(dgst.digest_size,20)
-		self.assertEqual(dgst.hexdigest(),"00CFFE7312BF9CA73584F24BDF7DF1D028340397")
+		self.assertEqual(dgst.hexdigest(),self.dgst)
+	def test_length(self):
+		l=len(self.msg)
+		msg=self.msg+" Dog barks furiously."
+		dgst=digest.new("sha1")
+		dgst.update(msg,length=l)
+		self.assertEqual(dgst.hexdigest(),self.dgst)
+	def test_badlength(self):
+		l=len(self.msg)
+		dgst=digest.new("sha1")
+		with self.assertRaises(ValueError):
+			dgst.update(self.msg,length=l+1)
 	def test_bindigest(self):
 		dgst=digest.new("sha1")
-		dgst.update("A quick brown fox jumps over the lazy dog.")
+		dgst.update(self.msg)
 		self.assertEqual(dgst.digest_size,20)
-		self.assertEqual(dgst.digest(),b16decode("00CFFE7312BF9CA73584F24BDF7DF1D028340397",True)) 
+		self.assertEqual(dgst.digest(),b16decode(self.dgst,True)) 
 	def test_duplicatedigest(self):
 		dgst=digest.new("sha1")
-		dgst.update("A quick brown fox jumps over the lazy dog.")
+		dgst.update(self.msg)
 		v1=dgst.digest()
 		v2=dgst.digest()
 		self.assertEqual(v1,v2)
+	def test_updatefinalized(self):
+		dgst=digest.new("sha1")
+		dgst.update(self.msg)
+		h=dgst.hexdigest()
+		with self.assertRaises(digest.DigestError):
+			dgst.update(self.msg)
+	def test_wrongtype(self):
+		dgst=digest.new("sha1")
+		with self.assertRaises(TypeError):
+			dgst.update(['a','b','c'])
+		with self.assertRaises(TypeError):
+			dgst.update(18)
+		with self.assertRaises(TypeError):
+			dgst.update({"a":"b","c":"D"})
+		with self.assertRaises(TypeError):
+			dgst.update(u'\u0430\u0431')
 	def test_copy(self):
 		dgst=digest.new("sha1")
 		dgst.update("A quick brown fox jumps over ")
@@ -93,6 +122,9 @@ class TestAlgo(unittest.TestCase):
 		self.assertEqual(d.digest_size,64)
 		d.update("A quick brown fox jumps over the lazy dog.")
 		self.assertEqual(d.hexdigest(),"3045575CF3B873DD656F5F3426E04A4ACD11950BB2538772EE14867002B408E21FF18EF7F7B2CAB484A3C1C0BE3F8ACC4AED536A427353C7748DC365FC1A8646")
+	def test_wrongdigest(self):
+		with self.assertRaises(digest.DigestError):
+			dgst=digest.new("no-such-digest")
 
 if __name__ == "__main__":
 	unittest.main()
-- 
2.39.2