Make JNI code more robust

ports/libsimpleservo/src/api.rs

@@ -28,6 +28,14 @@ thread_local! {
 /// and that perform_updates need to be called
 pub use servo::embedder_traits::EventLoopWaker;
 
+pub struct InitOptions {
+    pub args: Option<String>,
+    pub url: Option<String>,
+    pub width: u32,
+    pub height: u32,
+    pub density: f32,
+}
+
 /// Delegate resource file reading to the embedder.
 pub trait ReadFileTrait {
     fn readfile(&self, file: &str) -> Vec<u8>;
@@ -93,28 +101,24 @@ pub fn servo_version() -> String {
 /// Initialize Servo. At that point, we need a valid GL context.
 /// In the future, this will be done in multiple steps.
 pub fn init(
+    init_opts: InitOptions,
     gl: Rc<gl::Gl>,
-    argsline: String,
-    embedder_url: Option<String>,
     waker: Box<EventLoopWaker>,
     readfile: Box<ReadFileTrait + Send + Sync>,
     callbacks: Box<HostTrait>,
-    width: u32,
-    height: u32,
-    density: f32,
 ) -> Result<(), &'static str> {
     resources::set(Box::new(ResourceReader(readfile)));
 
-    if !argsline.is_empty() {
-        let mut args: Vec<String> = serde_json::from_str(&argsline).map_err(|_| {
+    if let Some(args) = init_opts.args {
+        let mut args: Vec<String> = serde_json::from_str(&args).map_err(|_| {
             "Invalid arguments. Servo arguments must be formatted as a JSON array"
         })?;
         // opts::from_cmdline_args expects the first argument to be the binary name.
         args.insert(0, "servo".to_string());
         opts::from_cmdline_args(&args);
     }
 
-    let embedder_url = embedder_url.as_ref().and_then(|s| {
+    let embedder_url = init_opts.url.as_ref().and_then(|s| {
         ServoUrl::parse(s).ok()
     });
     let cmdline_url = opts::get().url.clone();
@@ -135,9 +139,9 @@ pub fn init(
     let callbacks = Rc::new(ServoCallbacks {
         gl: gl.clone(),
         host_callbacks: callbacks,
-        width: Cell::new(width),
-        height: Cell::new(height),
-        density,
+        width: Cell::new(init_opts.width),
+        height: Cell::new(init_opts.height),
+        density: init_opts.density,
         waker,
     });
 

ports/libsimpleservo/src/capi.rs

@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use api::{self, EventLoopWaker, ServoGlue, SERVO, HostTrait, ReadFileTrait};
+use api::{self, EventLoopWaker, InitOptions, ServoGlue, SERVO, HostTrait, ReadFileTrait};
 use gl_glue;
 use servo::gl;
 use std::ffi::{CStr, CString};
@@ -37,6 +37,16 @@ pub struct CHostCallbacks {
     pub on_animating_changed: extern fn(animating: bool),
 }
 
+/// Servo options
+#[repr(C)]
+pub struct CInitOptions {
+    pub args: *const c_char,
+    pub url: *const c_char,
+    pub width: u32,
+    pub height: u32,
+    pub density: f32,
+}
+
 /// The returned string is not freed. This will leak.
 #[no_mangle]
 pub extern "C" fn servo_version() -> *const c_char {
@@ -48,66 +58,52 @@ pub extern "C" fn servo_version() -> *const c_char {
 }
 
 fn init(
+    opts: CInitOptions,
     gl: Rc<gl::Gl>,
-    args: *const c_char,
-    url: *const c_char,
     wakeup: extern fn(),
     readfile: extern fn(*const c_char) -> *const c_char,
-    callbacks: CHostCallbacks,
-    width: u32,
-    height: u32,
-    density: f32) {
-    let args = unsafe { CStr::from_ptr(args) };
-    let args = args.to_str().expect("Can't read string").to_string();
+    callbacks: CHostCallbacks) {
+    let args = unsafe { CStr::from_ptr(opts.args) };
+    let args = args.to_str().map(|s| s.to_string()).ok();
 
-    let url = unsafe { CStr::from_ptr(url) };
-    let url = url.to_str().map(|s| s.to_string());
+    let url = unsafe { CStr::from_ptr(opts.url) };
+    let url = url.to_str().map(|s| s.to_string()).ok();
+
+    let opts = InitOptions {
+        args,
+        url,
+        width: opts.width,
+        height: opts.height,
+        density: opts.density,
+    };
 
     let wakeup = Box::new(WakeupCallback::new(wakeup));
     let readfile = Box::new(ReadFileCallback::new(readfile));
     let callbacks = Box::new(HostCallbacks::new(callbacks));
 
-    api::init(
-        gl,
-        args,
-        url.ok(),
-        wakeup,
-        readfile,
-        callbacks,
-        width,
-        height,
-        density,
-    ).unwrap();
+    api::init(opts, gl, wakeup, readfile, callbacks).unwrap();
 }
 
 #[cfg(target_os = "windows")]
 #[no_mangle]
 pub extern "C" fn init_with_egl(
-    args: *const c_char,
-    url: *const c_char,
+    opts: CInitOptions,
     wakeup: extern fn(),
     readfile: extern fn(*const c_char) -> *const c_char,
-    callbacks: CHostCallbacks,
-    width: u32,
-    height: u32,
-    density: f32) {
+    callbacks: CHostCallbacks) {
     let gl = gl_glue::egl::init().unwrap();
-    init(gl, args, url, wakeup, readfile, callbacks, width, height, density)
+    init(opts, gl, wakeup, readfile, callbacks)
 }
 
 #[cfg(any(target_os = "linux", target_os = "windows", target_os = "macos"))]
 #[no_mangle]
 pub extern "C" fn init_with_gl(
-    args: *const c_char,
-    url: *const c_char,
+    opts: CInitOptions,
     wakeup: extern fn(),
     readfile: extern fn(*const c_char) -> *const c_char,
-    callbacks: CHostCallbacks,
-    width: u32,
-    height: u32,
-    density: f32) {
+    callbacks: CHostCallbacks) {
     let gl = gl_glue::gl::init().unwrap();
-    init(gl, args, url, wakeup, readfile, callbacks, width, height, density)
+    init(opts, gl, wakeup, readfile, callbacks)
 }
 
 #[no_mangle]