add sanity check for theoretical unsigned integer overflow in daemon …

…interface removal handling, fix testcase lacking correct interface count initialization, improve error message placement in image output

src/daemon.c

@@ -723,7 +723,9 @@ void cleanremovedinterfaces(DSTATE *s)
 			snprintf(errorstring, 1024, "Removing interface \"%s\" from update list.", dbifl_iterator->interface);
 			printe(PT_Info);
 			datacache_remove(&s->dcache, dbifl_iterator->interface);
-			s->dbifcount--;
+			if (s->dbifcount > 0) {
+				s->dbifcount--;
+			}
 			dbifl_iterator = dbifl_iterator->next;
 		}
 		datacache_status(&s->dcache);

src/image.c

@@ -329,7 +329,7 @@ int drawhours(IMAGECONTENT *ic, const int x, const int y, const int rate)
 	}
 
 	if (datainfo.count == 0) {
-		gdImageString(ic->im, gdFontGetSmall(), 200, 100, (unsigned char *)"no data available", ic->ctext);
+		gdImageString(ic->im, gdFontGetSmall(), x + 188, y + 54, (unsigned char *)"no data available", ic->ctext);
 		return 0;
 	}
 

tests/daemon_tests.c

@@ -468,6 +468,7 @@ START_TEST(processdatacache_can_process_things)
 	s.bootdetected = 1;
 	s.dodbsave = 1;
 	s.cleanuphour = getcurrenthour() + 1;
+	s.dbifcount = 3;
 
 	ck_assert_int_eq(datacache_count(&s.dcache), 0);
 	ret = datacache_add(&s.dcache, "ethnotindb", 0);