Add asserts to do_hash_buffer to detect misuse

Related to issue #374.

diff --git a/src/hash.c b/src/hash.c
index ae303322a2b893b13b1ada5eed69464a8a9b6a72..ae89e85fe8e668e1d256f24d86ffd21f8b24e317 100644 (file)
--- a/src/hash.c
+++ b/src/hash.c
@@ -1,5 +1,5 @@
 // Copyright (C) 2002 Andrew Tridgell
-// Copyright (C) 2010-2018 Joel Rosdahl
+// Copyright (C) 2010-2019 Joel Rosdahl
 //
 // This program is free software; you can redistribute it and/or modify it
 // under the terms of the GNU General Public License as published by the Free
@@ -30,6 +30,12 @@ struct hash {
 static void
 do_hash_buffer(struct hash *hash, const void *s, size_t len)
 {
+       assert(s);
+
+       // The hash state cannot be updated after the result has been fetched via
+       // hash_result/hash_result_as_bytes.
+       assert(!hash->md.finalized);
+
        mdfour_update(&hash->md, (const unsigned char *)s, len);
        if (len > 0 && hash->debug_binary) {
                (void) fwrite(s, 1, len, hash->debug_binary);