Make dc_open arguments rusty

examples/repl/cmdline.rs

@@ -503,10 +503,7 @@ pub unsafe fn dc_cmdline(context: &Context, line: &str) -> Result<(), failure::E
         "open" => {
             ensure!(!arg1.is_empty(), "Argument <file> missing");
             dc_close(context);
-            ensure!(
-                0 != dc_open(context, arg1_c, 0 as *const libc::c_char),
-                "Open failed"
-            );
+            ensure!(dc_open(context, arg1, None), "Open failed");
         }
         "close" => {
             dc_close(context);

examples/repl/main.rs

@@ -399,12 +399,7 @@ fn main_0(args: Vec<String>) -> Result<(), failure::Error> {
     unsafe { dc_cmdline_skip_auth() };
 
     if args.len() == 2 {
-        if 0 == unsafe {
-            let a = to_cstring(&args[1]);
-            let res = dc_open(&mut context, a, 0 as *const _);
-            free(a as *mut _);
-            res
-        } {
+        if unsafe { !dc_open(&mut context, &args[1], None) } {
             println!("Error: Cannot open {}.", args[0],);
         }
     } else if args.len() != 1 {