Get option descriptor 0 before trying to read the value for option 0.

ChangeLog

@@ -1,3 +1,7 @@
+2008-08-04 Julien Blache <jb@jblache.org>
+	* frontend/scanimage.c: fetch_options(), actually get option
+	descriptor 0 before attempting to get the value of option 0.
+
 2008-08-04  Stéphane Voltz <stef.dev@free.fr>
 	* backend/umax_pp.c backend/umaxp_pp.h backend/umax_pp.conf.in: 
 	  use configuration framework

frontend/scanimage.c

@@ -838,15 +838,33 @@ fetch_options (SANE_Device * device)
   const SANE_Option_Descriptor *opt;
   SANE_Int num_dev_options;
   int i, option_count;
+  SANE_Status status;
 
   /* and now build the full table of long options: */
 
-  sane_control_option (device, 0, SANE_ACTION_GET_VALUE, &num_dev_options, 0);
+  opt = sane_get_option_descriptor (device, 0);
+  if (opt == NULL)
+    {
+      fprintf (stderr, "Could not get option descriptor for option 0\n");
+      exit (1);
+    }
+
+  status = sane_control_option (device, 0, SANE_ACTION_GET_VALUE, &num_dev_options, 0);
+  if (status != SANE_STATUS_GOOD)
+    {
+      fprintf (stderr, "Could not get value for option 0: %s\n", sane_strstatus (status));
+      exit (1);
+    }
 
   option_count = 0;
-  for (i = 0; i < num_dev_options; ++i)
+  for (i = 1; i < num_dev_options; ++i)
     {
       opt = sane_get_option_descriptor (device, i);
+      if (opt == NULL)
+	{
+	  fprintf (stderr, "Could not get option descriptor for option %d\n", i);
+	  exit (1);
+	}
 
       if (!SANE_OPTION_IS_SETTABLE (opt->cap))
 	continue;