fix buffer overrun

1 files changed, 3 insertions, 2 deletions

diff --git a/utils/b64tools.cc b/utils/b64tools.cc
index 5512f975..78c1cb4e 100644
--- a/utils/b64tools.cc
+++ b/utils/b64tools.cc
@@ -10,9 +10,10 @@ static const char cd64[]="|$$$}rstuvwxyz{$$$$$$$>?@ABCDEFGHIJKLMNOPQRSTUVW$$$$$$
 
 static void encodeblock(const unsigned char* in, ostream* os, int len) {
   char out[4];
+  // cerr << len << endl;
   out[0] = cb64[ in[0] >> 2 ];
-  out[1] = cb64[ ((in[0] & 0x03) << 4) | ((in[1] & 0xf0) >> 4) ];
-  out[2] = (len > 1 ? cb64[ ((in[1] & 0x0f) << 2) | ((in[2] & 0xc0) >> 6) ] : '=');
+  out[1] = cb64[ ((in[0] & 0x03) << 4) | (len > 1 ? ((in[1] & 0xf0) >> 4) : static_cast<unsigned char>(0))];
+  out[2] = (len > 2 ? cb64[ ((in[1] & 0x0f) << 2) | ((in[2] & 0xc0) >> 6) ] : '=');
   out[3] = (len > 2 ? cb64[ in[2] & 0x3f ] : '=');
   os->write(out, 4);
 }