Fix potential overflow in base64_encode
diff --git a/include/polarssl/base64.h b/include/polarssl/base64.h
index db95cb1..8b772df 100644
--- a/include/polarssl/base64.h
+++ b/include/polarssl/base64.h
@@ -25,6 +25,7 @@
#define POLARSSL_BASE64_H
#include <string.h>
+#include <limits.h>
#define POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL -0x002A /**< Output buffer too small. */
#define POLARSSL_ERR_BASE64_INVALID_CHARACTER -0x002C /**< Invalid character in input. */
@@ -44,6 +45,8 @@
* \return 0 if successful, or POLARSSL_ERR_BASE64_BUFFER_TOO_SMALL.
* *dlen is always updated to reflect the amount
* of data that has (or would have) been written.
+ * If that length cannot be represented, then no data is
+ * written to the buffer and *dlen is set to SIZE_T_MAX.
*
* \note Call this function with *dlen = 0 to obtain the
* required buffer size in *dlen