From bda6bc47d71b962bec00142bd5ae5b8b76b142b9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jonas=20Borgstr=C3=B6m?= <jonas@borgstrom.se>
Date: Sun, 2 Jun 2013 15:55:23 +0200
Subject: [PATCH] Use buffer instead of string slicing to reduce memory usage.

---
 darc/key.py    | 10 +++++-----
 darc/remote.py |  4 ++--
 darc/test.py   |  3 +++
 3 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/darc/key.py b/darc/key.py
index 1a2ba18b6..700294998 100644
--- a/darc/key.py
+++ b/darc/key.py
@@ -83,7 +83,7 @@ def encrypt(self, data):
     def decrypt(self, id, data):
         if data[0] != self.TYPE:
             raise IntegrityError('Invalid encryption envelope')
-        data = zlib.decompress(data[1:])
+        data = zlib.decompress(buffer(data, 1))
         if id and SHA256.new(data).digest() != id:
             raise IntegrityError('Chunk id verification failed')
         return data
@@ -107,12 +107,12 @@ def encrypt(self, data):
     def decrypt(self, id, data):
         if data[0] != self.TYPE:
             raise IntegrityError('Invalid encryption envelope')
-        hash = data[1:33]
-        if HMAC.new(self.enc_hmac_key, data[33:], SHA256).digest() != hash:
+        hash = buffer(data, 1, 32)
+        if buffer(HMAC.new(self.enc_hmac_key, buffer(data, 33), SHA256).digest()) != hash:
             raise IntegrityError('Encryption envelope checksum mismatch')
-        nonce = bytes_to_long(data[33:41])
+        nonce = bytes_to_long(buffer(data, 33, 8))
         counter = Counter.new(64, initial_value=nonce, prefix=PREFIX)
-        data = zlib.decompress(AES.new(self.enc_key, AES.MODE_CTR, counter=counter).decrypt(data[41:]))
+        data = zlib.decompress(AES.new(self.enc_key, AES.MODE_CTR, counter=counter).decrypt(buffer(data, 41)))
         if id and HMAC.new(self.id_key, data, SHA256).digest() != id:
             raise IntegrityError('Chunk id verification failed')
         return data
diff --git a/darc/remote.py b/darc/remote.py
index 3a13e7c23..b5bba1c31 100644
--- a/darc/remote.py
+++ b/darc/remote.py
@@ -127,7 +127,7 @@ def call(self, cmd, args, wait=True):
                 if to_send:
                     n = os.write(self.stdin_fd, to_send)
                     assert n > 0
-                    to_send = to_send[n:]
+                    to_send = buffer(to_send, n)
                 else:
                     w_fds = []
 
@@ -212,7 +212,7 @@ def call_multi(self, cmd, argsv, wait=True, peek=None):
                 if self.to_send:
                     n = os.write(self.stdin_fd, self.to_send)
                     assert n > 0
-                    self.to_send = self.to_send[n:]
+                    self.to_send = buffer(self.to_send, n)
                 else:
                     w_fds = []
                     if not wait:
diff --git a/darc/test.py b/darc/test.py
index bb318ddde..d1a065c25 100644
--- a/darc/test.py
+++ b/darc/test.py
@@ -92,6 +92,9 @@ def diff_dirs(self, dir1, dir2):
                 attrs.append('st_mtime')
             d1 = [filename] + [getattr(s1, a) for a in attrs]
             d2 = [filename] + [getattr(s2, a) for a in attrs]
+            if(len(d1) == 6):
+                d1[-1] = int(d1[-1])
+                d2[-1] = int(d2[-1])
             d1.append(self.get_xattrs(path1))
             d2.append(self.get_xattrs(path2))
             self.assertEqual(d1, d2)