{md5,sha256}_ext.c: comments added

1 files changed, 4 insertions, 1 deletions

diff --git a/src/microhttpd/sha256_ext.c b/src/microhttpd/sha256_ext.c
index d1c2a6ed..f8cae555 100644
--- a/src/microhttpd/sha256_ext.c
+++ b/src/microhttpd/sha256_ext.c
@@ -42,11 +42,14 @@ MHD_SHA256_init_one_time (struct Sha256CtxExt *ctx)
   ctx->ext_error = gnutls_hash_init (&ctx->handle, GNUTLS_DIG_SHA256);
   if ((0 != ctx->ext_error) && (NULL != ctx->handle))
   {
+    /* GnuTLS may return initialisation error and set the handle at the
+       same time. Such handle cannot be used for calculations.
+       Note: GnuTLS may also return an error and NOT set the handle. */
     gnutls_free (ctx->handle);
     ctx->handle = NULL;
   }
   else
-    mhd_assert (NULL != ctx->handle);
+    mhd_assert (NULL != ctx->handle); /* If error is not returned, the handle must not be NULL */
 }