fuzzing: Ensure input to g_uri_parse() is nul-terminated

The fuzzer will produce arbitrary binary blobs, which might not be
nul-terminated. `g_uri_parse()` has no length argument, so relies on
receiving a nul-terminated string as input. Guarantee that.

This should fix fuzzing build failures like
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=23750.
Signed-off-by: Philip Withnall <withnall@endlessm.com>

fuzzing/fuzz_uri_parse.c

@@ -3,14 +3,18 @@
 int
 LLVMFuzzerTestOneInput (const unsigned char *data, size_t size)
 {
+  unsigned char *nul_terminated_data = NULL;
   GUri *uri = NULL;
   gchar *uri_string = NULL;
   const GUriFlags flags = G_URI_FLAGS_NONE;
 
   fuzz_set_logging_func ();
 
-  /* ignore @size */
+  /* ignore @size (g_uri_parse() doesn’t support it); ensure @data is nul-terminated */
+  nul_terminated_data = (unsigned char *) g_strndup ((const gchar *) data, size);
   uri = g_uri_parse ((const gchar *) data, flags, NULL);
+  g_free (nul_terminated_data);
+
   if (uri == NULL)
     return 0;