From 3cc6344c8b8e8e4baf723c8399a901f6d891ac13 Mon Sep 17 00:00:00 2001
From: Simeon Morgan <smorgan@digitalfeed.net>
Date: Tue, 12 Nov 2013 13:31:30 +1100
Subject: [PATCH] Optimised use of buffers when decrypting to avoid unnecessary
 array copying

---
 .../securesms/crypto/DecryptingPartInputStream.java         | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/org/thoughtcrime/securesms/crypto/DecryptingPartInputStream.java b/src/org/thoughtcrime/securesms/crypto/DecryptingPartInputStream.java
index 5c6a4d72c2..55549a298b 100644
--- a/src/org/thoughtcrime/securesms/crypto/DecryptingPartInputStream.java
+++ b/src/org/thoughtcrime/securesms/crypto/DecryptingPartInputStream.java
@@ -156,6 +156,12 @@ public class DecryptingPartInputStream extends FileInputStream {
 
       //data retrieved using cipher.update doesn't always match cipher.getOutputSize (but should never be larger)
       int outputLen = cipher.getOutputSize(read);
+
+      if (outputLen < length) {
+        readLength += cipher.update(internalBuffer, 0, read, buffer, offset);
+        return readLength;
+      }
+
       byte[] transientBuffer = new byte[outputLen];
       outputLen = cipher.update(internalBuffer, 0, read, transientBuffer, 0);
       if (outputLen <= length) {