Use dynamically allocated string in struct io_file

Avoid using fixed-size buffers and strncpy().

Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>

src/calcurse.h

@@ -510,7 +510,7 @@ struct notify_app {
 
 struct io_file {
 	FILE *fd;
-	char name[BUFSIZ];
+	char *name;
 };
 
 /* Available keys. */