From: Pierre Ossman <ossman@cendio.se>
Date: Sat, 16 May 2020 09:32:26 +0000 (+0200)
Subject: Don't shuffle input buffer unless actually needed
X-Git-Tag: v1.11.90~74^2~12
X-Git-Url: https://source.dussan.org/?a=commitdiff_plain;h=c2bbdb573d546eb88539d1204b84cb48d910191a;p=tigervnc.git

Don't shuffle input buffer unless actually needed
---

diff --git a/common/rdr/BufferedInStream.cxx b/common/rdr/BufferedInStream.cxx
index 64cdb667..967e5a54 100644
--- a/common/rdr/BufferedInStream.cxx
+++ b/common/rdr/BufferedInStream.cxx
@@ -51,12 +51,14 @@ bool BufferedInStream::overrun(size_t needed, bool wait)
                     "requested size of %lu bytes exceeds maximum of %lu bytes",
                     (long unsigned)needed, (long unsigned)bufSize);
 
-  if (end - ptr != 0)
+  // Do we need to shuffle things around?
+  if ((bufSize - (ptr - start)) < needed) {
     memmove(start, ptr, end - ptr);
 
-  offset += ptr - start;
-  end -= ptr - start;
-  ptr = start;
+    offset += ptr - start;
+    end -= ptr - start;
+    ptr = start;
+  }
 
   while (avail() < needed) {
     if (!fillBuffer(start + bufSize - end, wait))